S488 Heart Rhythm, Vol. 15, No. 5, May Supplement POSTER B-PO05: Poster Session V B-PO B-PO B-PO05-002

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1 S488 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 POSTER B-PO05: Poster Session V Friday, May 11, :00 PM - 4:30 PM B-PO THE MAGUK PROTEIN CASK DOWN REGULATES A SUBPOPULATION OF CARDIAC SODIUM CHANNELS THROUGH L27B AND GUK DOMAINS AT THE LATERAL MEMBRANE OF CARDIOMYOCYTES Adeline Beuriot, MS, Catherine Eichel, Florent Louault, Alain Coulombe, Stephane Hatem, MD and Elise Balse, PhD. INSERM UMRS_1166, Paris, France, Department of Neurosciences, Madison, WI, Faculte de Medecine Pitie Salpetriere, Paris, France Background: CASK (Calcium/Calmodulin-dependent Serine protein Kinase) is a MAGUK (Membrane-Associated Guanylate Kinase) protein involved in the negative regulation of the sodium current (I Na ) in cardiac myocytes (CM). For now, the mechanisms of this regulation are not fully understood. Objective: As CASK contains multiple protein-protein interaction domains our aim was to investigate which functional domain(s) of CASK is/are responsible for interaction with Na V 1.5 channels and for the negative regulation of I Na. Methods: We designed seven adenoviral CASK constructs with a single functional domain truncated at the time (CASK ΔCAMKII, CASK ΔL27A, CASK ΔL27B, CASK ΔPDZ, CASK ΔSH3, CASK ΔHOOK and CASK ΔGUK ) to overexpress the protein in adult rat CM. GFP and the WT CASK protein served as controls. The effect of the overexpression of the different constructs were investigated using patch clamp electrophysiology, RT-qPCR, biochemistry and high resolution 3-dimensional deconvolution microscopy. Results: Whole-cell patch-clamp experiments showed that CASK WT overexpression reduced I Na whereas CASK ΔL27B and CASK ΔGUK constructs completely or partially restored I Na. Immunostainings revealed that the deletion of either L27B or GUK domain enhanced the expression of Na V 1.5 at the membrane of CM compared to CASK WT overexpression. Finally, RT-qPCR and western blot experiments showed that mrna and protein levels of Na V 1.5 were not increased by either CASK ΔL27B or CASK ΔGUK overexpression. Conclusion: These results indicate that the rescue of I Na upon CASK ΔL27B or CASK ΔGUK overexpression was nor transcriptional nor translational and rather due to an increased surface expression of Na V 1.5. A likely explanation is that CASK impedes anterograde trafficking and/or stabilization of Na V 1.5 channels at the sarcolemma through interactions with either L27B or GUK domain. This hypothesis will be investigated using time lapse experiments to follow Na V 1.5 trafficking in CM overexpressing CASK, CASK ΔL27B or CASK ΔGUK. GST pull-down assays will be performed to investigate which domain of CASK is involved in the interaction with the channel. B-PO ATRIAL ARRHYTHMOPATHY-ASSOCIATED REMODELING OF TWO PORE-DOMAIN POTASSIUM (K 2P ) CHANNELS IN MURINE DISEASE MODELS - FOCUS ON TASK-1 Felix Wiedmann, Jan Schulte, Bruna Gomes, Antonius Ratte, Frank Ulrich Müller, Niels Voigt, MD, Maria-Patapia Zafeiriou, Matthias Karck, Gábor Szabó, Ursula Tochtermann, Arjang Ruhparwar, Hugo A. Katus, Dierk Thomas and Constanze Schmidt. University of Münster, Institut for Pharmacology and Toxicology, Münster, Germany, University Hospital Heidelberg, Department of Internal Medicine III, Heidelberg, Germany, Dresden University of Technology, Dresden, Germany, University Medical Center Goettingen, Institute of Pharmacology and Toxicology, Goettingen, Germany, University Hospital Heidelberg, Department of Heart Surgery, Heidelberg, Germany Background: Understanding molecular mechanisms involved in atrial arrythmopathy and tissue remodeling is essential for developing specific therapeutic approaches. Two-pore-domain potassium (K 2P ) channels modulate cellular excitability and TASK-1 (K 2P 3.1) currents were recently shown to regulate atrial action potential duration in atrial fibrillation (AF) and heart failure (HF). Objective: Finding animal models that closely resemble pathophysiological alterations in human is a challenging task. To compare animal models with human pathophysiology of AF, we analyzed the expression and the remodeling of K 2P channels in murine models of AF and HF in comparison to a large animal model and patient tissue samples. Methods: Expression levels were quantified by qpcr and immunoblot in mouse models of AF (camp-response element modulator (CREM)-IbΔC-X transgenic (TG) animals) or HF (cardiac dysfunction induced by transverse aortic constriction, TAC). Data were compared to tissue samples obtained from patients undergoing open heart surgery and samples from a porcine model of atrial tachypacing-induced AF and HF. Results: In murine models, among members of the K 2P channel family, TASK-1 (i.e. K 2P 3.1) expression displayed highest levels in both atrial and ventricular tissue samples. Furthermore, K 2P 6.1, K 2P 2.1, K 2P 5.1 and K 2P 15.1 showed significant expression levels. Expression of K 2P 4.1, K 2P 7.1, K 2P 9.1, K 2P 12.1 was negligible. In CREM-TG mice, atrial expression of TASK-1 was significantly reduced in comparison to wild type animals. In contrast, AF patients showed significant upregulation of atrial TASK-1 levels. Ventricular TASK-1 levels remained unchanged in CREM-TG and TAC mice, which was similarly observed in AF/HF patients and pigs. Atrial K 2P 2.1 levels were reduced in CREM-TG mice, AF/HF pigs and AF patients in a similar manner. Ventricular expression of K 2P 6.1 was not dysregulated in CREM-TG mice but significantly upregulated in a murine model of TAC induced pressure overload. Conclusion: In conclusion, atrial remodeling of cardiac K 2P channels varies among different species. Compared to murine AF models, the porcine tachypacing-induced AF model showed higher similarity with pathophysiological alterations observed in human. B-PO HIPSC GENE-EDITING ESTABLISHES PATHOGENICITY OF A NOVEL LONG QT TYPE 8 VARIANT Nikhil Chavali, Dmytro O. Kryshtal, Shan S. Parikh, Lili Wang, Moore B. Shoemaker, MD and Bjorn C. Knollmann, MD, PhD. Vanderbilt University School of Medicine, Nashville, TN, Vanderbilt University Medical Center, Nashville, TN, Vanderbilt University, Nashville, TN, Vanderbilt Univ School of Medicine, Medicine and Pharmacology, Nashville, TN Background: The use of commercial genetic testing for Long QT Syndrome (LQTS) has rapidly expanded, but the inability to accurately predict whether a rare variant is pathogenic has limited clinical benefit. Novel missense variants detected by commercial genetic testing are routinely reported as a Variant of Undetermined Significance (VUS), which cannot be used to screen family members at-risk for sudden cardiac death. The development of new approaches to determine the pathogenicity of rare variants is a major unmet need. Objective: To use human induced pluripotent stem cell (hipsc) and gene-editing technology to evaluate the pathogenicity of

2 Poster Session V S489 a VUS in CACNA1C (LQT 8) encoding L-type Ca channels (LTCC). Methods: A novel, heterozygous missense variant (N639T) was detected by commercial genetic testing and reported as a VUS in a family with LQTS. Using CRISPR/Cas9 gene editing, the VUS was introduced into healthy hipscs and differentiated into cardiomyocytes (CMs). Electrophysiologic properties of edited cells were compared against isogenic and population control hipsc-cms lacking the VUS by measuring the electric field potential (EFP) of optogenetically paced 2D hipsc-cm monolayers, and by standard patch-clamp. Results: Electrophysiologic studies revealed significant EFP prolongation in all 3 heterozygous N639T hipsc lines (Fig. 1). Patch clamp studies showed N639T prolonged the ventricular action potential by slowing voltage-dependent LTCC inactivation (tau: ictrl 61±13 ms, N639T 142±24 ms, n=8-10, p<0.01). Conclusion: Genetic editing of hipscs can rapidly and efficiently establish pathogenicity of a VUS in LQTS such as the CACNA1C-N639T mutation. (SADS). Objective: We sought to characterize genotype-phenotype correlation in BrS and SADS families with reported pathogenic SCN1B variants and to review their pathogenicity. Methods: BrS and SADS families were reviewed from six inherited arrhythmia centers worldwide as well as a comprehensive literature review. Clinical characteristics including relevant history, electrocardiogram, and drug provocation testing were reviewed. SCN1B genetic result was reviewed and pathogenicity interpreted using American College of Medical Genetics criteria. Results: A total of 23 SCN1B genotype positive individuals were identified from 8 families. Four (17%) probands experienced ventricular fibrillation at the time of presentation. No family members had any syncope or ventricular arrhythmias. Only 2/23 (9%) genotype positive individuals demonstrated a spontaneous BrS ECG pattern. Of the individuals who underwent drug challenge testing for BrS 13/15 (87%) were negative. There was no difference in PR (161±7 vs 165±9ms; p=0.83), QRS (102±6 vs 89±5ms; p=0.35) or QTc (414±8 vs 405±5; p=0.67) intervals between genotype positive and genotype negative family members. Review of specific SCN1B genotype revealed 15/23 (65%) individuals with Trp179X mutation. This variant is present in general population control data and is located on an alternately spliced exon. Control population data shows this to be a region with high frequency of loss of function variants, suggesting loss of function is well tolerated in this region. The overall frequency of previously reported pathogenic SCN1B variants in gnomad browser of 0.004% exceeds the estimated frequency of BrS due to SCN1B (0.0005%). Conclusion: The lack of genotype-phenotype concordance amongst families, combined with the high number of loss of function variants in the gene and frequency of previously reported mutations in the gnomad browser suggests that SCN1B is not a monogenic cause for BrS or SADS cases. B-PO B-PO LACK OF GENOTYPE-PHENOTYPE CORRELATION IN BRUGADA SYNDROME AND SUDDEN ARRHYTHMIC DEATH SYNDROME FAMILIES WITH REPORTED PATHOGENIC SCN1B VARIANTS Belinda R. Gray, MBBS, PhD, Can Hasdemir, MD, Jodie Ingles, Takeshi Aiba, MD,PhD, Naomasa Makita, MD, PhD, Vincent Probst, MD, Arthur A. M. Wilde, MD, PhD, Christopher Semsarian, MBBS, MPH, PhD, FHRS, Raymond W. Sy, MBBS, PhD and Elijah Behr. St George s University of London, London, United Kingdom, Ege Univ School of Medicine, Bornova, Izmir, Turkey, University of Sydney, Sydney, Australia, National Cerebral and Cardiovascular Center, Suita, Japan, Nagasaki University, Nagasaki, Japan, CHU de Nantes, Nantes, France, Univ of Amsterdam - Academic Medical Center, Amsterdam, Netherlands, University of Sydney, Newtown, Australia, Royal Prince Alfred Hospital, Sydney, Australia Background: There is limited evidence for monogenic Brugada Syndrome (BrS) due to mutations in SCN1B variants (BrS 5). This gene may be inappropriately included in routine genetic testing panels for BrS or sudden arrhythmic death syndrome ENHANCED NUCLEOSIDE DIPHOSPHATE KINASE CAUSES PROARRHYTHMIC CA 2+ -HANDLING ABNORMALITIES IN CANINE ATRIAL CARDIOMYOCYTES Issam Abu Taha, PhD, Marina Schaefer, Xiao-Yan Qi, PhD, Patrice Naud, Vanessa Gundlach, Markus Kamler, MD, Jordi Heijman, PhD, Thomas Wieland, PhD, Stanley Nattel, MD, FHRS and Dobromir Dobrev, MD. Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen, Essen, Germany, Montreal Heart Institute, Montreal, QC, Canada, Montreal Heart Institute/Université de Montréal, Montreal, QC, Canada, Department of Thoracic and Cardiovascular Surgery Huttrop, University Duisburg-Essen, Essen, Germany, Maastricht University, Maastricht, Germany, Institute of Experimental and Clinical Pharmacology and Toxicology, Mannheim Medical Faculty, University of Heidelberg, Heidelberg, Germany, University of Duisburg-Essen, Essen, Germany Background: Atrial fibrillation (AF) is associated with elevated camp levels and abnormal Ca 2+ -handling. Nucleoside diphosphate kinases (NDPK-B and NDPK-C) increase G s protein and camp levels in a receptor-independent manner, and are upregulated in AF patients. Objective: To study whether increased NDPK expression results in aberrant Ca 2+ handling in canine atrial cardiomyocytes (CMs). Methods: CMs were paced at 1 Hz (P1) or 3 Hz (P3). NDPK-B and Flag-tagged-NDPK-C (NDPK-C) were adenovirally overexpressed in CMs. Protein levels were quantified by immunoblot, camp by immunoassay. Fractional

3 S490 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 shortening (video-edge detection) and Ca 2+ -transients (CaTs; epifluorescence with Indo-1-AM) were recorded in CMs overexpressing NDPK-B, Flag-NDPK-C or EGFP-control. Results: Protein expression of NDPK-B, NDPK-C, and Gα s (A) along with camp levels (B) were higher at P3, mimicking clinical AF. Overexpression of NDPK-B or Flag-NDPK-C also increased Gα s protein expression (C) and enhanced camp levels (D). Overexpression of NDPK-B or Flag-NDPK-C augmented CM fractional shortening (by 15.8% [NDPK-B, P<0.05] and 8.3% [Flag-NDPK-C, P<0.05] vs EGFP-control), likely as a consequence of the increased CaT amplitude (by 26.6% [NDPK-B, P<0.05] and 24.7% [Flag-NDPK-C, P<0.05] vs EGFP-control). Finally, the susceptibility of CMs to potentially proarrhythmic Ca 2+ early aftertransients (EATs) (E) and Ca 2+ alternans (F) was higher in CMs overexpressing NDPK-B or Flag-NPDK-C vs. EGFP-control. Conclusion: Our data show that the upregulation of NDPK isoforms in human AF might cause proarrhythmic Ca 2+ -handling abnormalities, which may contribute to AF-related triggered activity. Korea, Republic of, Division of Cardiology, Yonsei University Health System, Brain Korea 21 PLUS Pro, Seoul, Korea, Republic of, Division of Cardiology, Yonsei University College of Medicine, Seoul, Korea, Republic of Background: Exosome contains and delivers bioactive molecules critical to intracellular signaling. However, the role of exosome extracted from atrial fibrillation (AF) has not been evaluated. Recent work showed histone deacetylases 6 (HDAC6) to cause cardiac remodeling by derailment of proteostasis. Objective: This study evaluated the effect of exosome from AF patients on electrical characteristics, Ca 2+ release, histone deacetylases 6 (HDAC6) of HL-1 cells using tachypaing model Methods: Exosome was isolated from peripheral blood of AF (AF-Exo) and healthy control patients (Con-Exo) by Exo-quick. Exosomes were examined by TEM, NTA and Western blot. We analyzed contents of mirna, using the Affymetrix GeneChip mirna 3.0 array. mirna targets were computationally predicted by using target-prediction programs mirbase and TargetScan. PKH26-labeled exosomes were delivered to HL-1 atrial cardiomyocytes at 24 hours before the initiation of tachypacing (5Hz). The effects of AF-Exo and Con-Exo on tachypacing model of HL-1 atrial cardiomyocytes were examined using a confocal Ca 2+ imaging, immunoblotting. Results: In tachypacing model of HL-1 atrial cardiomyocytes, Ca 2 + wave frequency were increased and amplitude were decreased. In contrast, AF-Exo reduced Ca 2 + wave frequency by 53% (p=0.015), and increased Ca 2+ transient amplitude by 41% (p=0.021). However, Con-Exo had no effect. Tachypacing induced contractile dysfunction was prevented by AF-Exo, but not by Con-Exo. The depolymerization of microtubules through HDAC-6 were increased by the duration of tachypacing. The increase of depolymerization of microtubules were prevented by AF-Exo, but not by Con-Exo. In AF induced mouse heart, total CaMKIIδ (T-CaMKII) and phosphorylated CaMKIIδ (P-CaMKII) protein expression were significantly increased, but AF-Exo reduced the ratio of T-CaMKII and P-CaMKII (42%, p=0.001). Finally, the level of mirna 548az-5p, which is related with HDAC6 and CaMKII was significantly increased in AF-Exo and Con-Exo. Conclusion: Exosome was isolated from peripheral blood of AF protects AF-related atrial remodeling, by reducing HDAC6 via mirna 548az-5p. This finding suggests that exosome has a role in the progress of AF, and might be used as a therapeutic tool of AF. B-PO B-PO ANTIARRHYTHMIC EFFECTS OF EXOSOME EXTRACTED FROM SERUM OF ATRIAL FIBRILLATION PATIENTS BY INHIBITING HDAC6 VIA MIRNA 548AZ-5P Hyoeun Kim, Hyelim Park, Hyewon Park, B.S., Cui Shanyu, Dasom Mun, Seung-Hyun Lee, M.D., Yun Nuri and Boyoung Joung, MD. Yonsei University College of Medicine, Seoul, NA V 1.5 GAIN OF FUNCTION IN CARDIAC FIBROBLASTS MODIFIES THEIR PROLIFERATION, APOPTOSIS AND DIFFERENTIATION Claire Castro, MSc, Justine Patin, MSc, Franck Chizelle, MSc, Cynthia Ore Cerpa, PhD, Agnès Carcouët, BEng, Eva Le Pogam, BEng, Isabelle Baró, PhD, Flavien Charpentier, PhD and Mickaël Derangeon, PhD. L Institut du Thorax, Nantes, France Background: Cardiac fibroblasts (CFs) are the largest population of cells in the heart and form extensive structural networks with cardiomyocytes. CFs play many roles in cardiac pathophysiology. In particular, CFs regulate extracellular matrix. In some cardiac diseases, CFs differentiate into myofibroblasts leading to fibrosis. It was recently shown that the voltage-gated Na + channel Na v 1.5, classically known to be expressed in cardiomyocytes and involved in numerous cardiac diseases, is also expressed in human CFs. Objective: We hypothesized that functional alterations of Na v 1.5, encoded by SCN5A gene, in CFs could participate in the

4 Poster Session V S491 pathogenesis of cardiovascular diseases. Methods: To understand the role of Na v 1.5 in CFs we used mice with a heterozygous knock-in deletion of QKP amino-acids in Scn5a gene product (Scn5a +/ΔQKP ) which mimics a human mutation responsible for the long QT syndrome. These mice present an abnormally large persistent Na + current and dilated hearts. CFs from these mice were isolated with the Langendorff technique. Results: We observed that cultured CFs exhibited the same level of Na v 1.5 expression in Scn5a +/+ and Scn5a +/ΔQKP mice. Then, we showed a decrease of apoptosis for the CFs from Scn5a +/ΔQKP (2.78-fold decrease for cleaved caspase 3; n=5) associated with a 3.8-fold increase of proliferation (xcelligence system; n=17-18), leading to an increase of CFs number (3214 cells/cm 2 n=18 versus 9207 cells/cm 2 n=17). When we blocked the Na + current, we observed a low but significant decrease of proliferation of CFs from Scn5a +/ΔQKP with tetrodotoxin (1.19-fold; n=16) or with ranolazine (1.2-fold; n=13). Also, CFs from Scn5a +/ ΔQKP mice had a decreased expression of α-sma (α-smooth muscle actin) (1.47-fold; n=7), the differentiation marker of CFs into myofibroblasts, suggesting a reduction of differentiation capacity, associated with an 18.3-fold increased expression of TGF-β (n=7). Conclusion: These data suggest that Na v 1.5 gain of function in CFs could increase their proliferation and decrease their apoptosis and differentiation. These results confirm that Na v 1.5 expression in CFs impacts their functional properties, and gives a new understanding of cardiac pathophysiology. B-PO INSILICO TESTING OF ANTI-TACHYCARDIA PACING FROM AN EXTRAVASCULAR DEFIBRILLATOR SYSTEM WITH A LEAD IN THE MEDIASTINAL SPACE Darrell Jay Swenson, PhD and Vladimir P. Nikolski, PhD. Medtronic, Mounds View, MN, Medtronic Inc., Mounds View, MN Background: We previously reported on the feasibility of pacing by a novel extravascular (EV) ICD with a lead implanted in the mediastinal space through a minimally-invasive subxiphoid approach. In animal studies, we also demonstrated that EV ICD system can successfully pace at high rates that are required to deliver anti-tachycardia pacing (ATP). Several studies have shown that ATP reduces appropriate but unnecessary shocks and should be included in all ICDs including EV ICDs. However, the successful termination of ventricular arrhythmia with ATP delivered from the mediastinal space via non-contact pacing has not yet been demonstrated in humans. Objective: To demonstrate the successful termination of ventricular tachycardia with ATP delivered from electrodes in the mediastinal space using biofidelic insilico heart models. Methods: MRI imaging data was used to generate realistic numerical heart models that included infarcted areas, border zones, and survived tissues. The software CARPentry calculated the patterns of sustained reentrant excitations (SRE) that were initiated in these heart models using programmed electrical stimulation. Various ATP protocols were tested for different pairs of electrodes on a lead placed in the mediastinum. The ranges of ATP parameters that either successfully terminated or accelerated SRE were compared for all tested electrode combinations. The performance of ATP delivered from transvenous pacing electrodes was also analyzed as a benchmark. Results: In 114 ATP trials over 6 unique hearts each with 3 different VT circuits, non-contact electrodes in the mediastinum as well as electrodes on the RV endocardium successfully terminated 82% of SRE with burst and ramp ATP protocols using parameters currently available in ICDs. The rate of SRE acceleration was <1%. The model also revealed potential improvements in ATP efficacy that could be achieved by selecting specific pairs of stimulation electrodes and adjusting timing of ATP sequences. Conclusion: These results suggest that ATP from non-contact pacing electrodes located in the mediastinal space should be as effective as in current ICDs. Numerical modeling of SRE termination by ATP provides a valuable insight for selecting the best set of ATP parameters for an individual patient. B-PO MYOCYTE REMODELLING DUE TO FIBRO-FATTY INFILTRATIONS INFLUENCES ARRHYTHMOGENICITY Tim De Coster, MSc, Piet Claus, PhD and Alexander V. Panfilov, PhD. UGent, Gent, Belgium, KU Leuven, Leuven, Belgium, Physics and Astronomy, Gent, Belgium Background: There is increasing evidence that adipose tissue plays a role in the onset of AF. Modulation of the electrophysiological characteristics of atrial myocytes by adjacent epicardial adipose cells has been put forward as a contributing factor. Objective: Studying the underlying arrhythmogenic mechanisms resulting from the presence of adipose tissue in the human heart. Methods: We used the Courtemanche model for the normal (NT) and AF remodelled (AFR) human atrial myocyte. The AFR model has changes in 3 ionic currents, the L-type Ca current (I CaL ), transient outward K current (I to ) and ultra rapid delayed rectifying K current (I Kur ), resulting in a decreased APD. Coculture of epicardial adipocytes and left atrial myocytes has revealed important changes in ionic currents in a rabbit model. Based on these experimental data, we adapted 6 ion currents for adipose induced remodelling: I CaL, I to, I Kur, the Na current (I Na ), slow delayed rectifying K current (I Ks ) and inward rectifying K current (I K1 ). In a 2D tissue model containing a circular region of remodelled myocytes, burst pacing protocols are used to induce arrhythmias. Results: At 1 Hz pacing, the changes due to tissue remodelling are a higher resting membrane potential ( vs mv for NT, vs mv for AFR) and longer APD (APD 90 : 470 vs. 310 ms for NT, 450 vs. 230 ms for AFR). Simulations at tissue level show that in absence of adipose remodelling no arrhythmias are induced, while in the presence of remodelling we do observe them (first appearance at: 1.7 Hz for NT, 2.5 Hz for AFR). Conclusion: Ionic remodelling due to the presence of adipose tissue results in higher arrhythmogenicity, due to heterogeneity of the tissue.

5 S492 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO FIBROSIS PROMOTES ECTOPY AND CONDUCTION BLOCK IN POSTINFARCTION HEARTS Fernando Otaviano Campos, PhD, Yohannes C. Shiferaw, PHD, Rodrigo Weber dos Santos, PhD, Gernot Plank, PhD and Martin J. Bishop, PhD. King s College London, London, United Kingdom, California State University; Dept of Physics, Northridge, CA, Federal University of Juiz de Fora, Juiz de Fora, Brazil, Medical University of Graz, Graz, Austria, King`s College London, London, United Kingdom Background: Premature ventricular complexes (PVCs) have been shown to arise from triggered activity in the infarct border zone (BZ). At the cellular scale, spontaneous calcium release (SCR) events are a known cause of PVCs. In tissue, fibrosis can disrupt local coupling which may facilitate ectopy capture. However, the interplay between SCR-mediated triggered activity and fibrosis upon PVC formation in infarcted hearts has not been fully investigated. Objective: To employ computer simulations to investigate how fibrosis in the BZ can create a substrate for PVCs induced by SCRs. Methods: A stochastic model of SCR events and action potential was used to simulate different cardiac preparations with a calcium overloaded BZ. In-silico models of idealized as well as anatomically realistic cardiac infarct tissue were generated, including scar along with an isthmus with different widths. Fibrotic tissue with different densities were created and assigned to the BZ. Results: Probability of PVCs significantly increases with decreasing width of conducting isthmuses within 2D sheet models. Anatomically-realistic representations of intramural scars show that the heart s protective source-sink mismatch prevents PVC formation. In all cases, fibrosis is shown to disrupt this antiarrhythmic mechanism promoting PVCs (Fig. A). Fibrosis also gave rise to regions of rapid tissue expansion that enhanced source-sink mismatch facilitating conduction block of PVCs (Fig. B). Conclusion: Thin isthmuses as well as strands of surviving myocytes interspersed with fibrosis represent important sources of PVCs induced by SCRs. PVC formation is favored due to a lesser electrotonic load on these cells. B-PO INDUCTION OF SELF-TERMINATING POLYMORPHIC VENTRICULAR TACHYCARDIA CRITICALLY DEPENDS ON REPOLARIZATION GRADIENTS IN COMPUTER AND PORCINE MODELS OF LONG QT SYNDROME Jason D. Bayer, PhD, Veronique M.F. Meijborg, PhD, Lisa Gottlieb, MS, Charly Belterman, Laura Bear, Corentin Dallet, MS, MSE, MSEE, Bas J. Boukens, Master of Science, Remi Dubois, Edward J. Vigmond, PhD and Ruben Coronel, MD, PhD. IHU LIRYC/University of Bordeaux, Pessac, France, Academic Medical Center, Amsterdam, Netherlands, LIRYC Electrophysiology and Heart Model, Bordeaux-Pessac, France, Hopital Cardiologique Haut Leveque - Université Bordeaux, University Bordeaux, Pessac, France, Academic Medical Centre, Amsterdam, Netherlands Background: The mechanism of Torsade de Pointes in long QT syndrome is unknown but depends on bradycardia, hypokalemia and short-long-short cycles. This suggests that reentry and repolarization heterogeneity play roles. We hypothesized that a critical repolarization gradient predisposes myocardium to selfterminating polymorphic VT (stpvt). Objective: To test the impact of repolarization gradients on arrhythmia inducibility in computer and porcine models of long QT syndrome. Methods: Repolarization was varied in a 5x5 cm computer model of human ventricular myocardium. Baseline maximal IKr conductance was increased throughout by 1-10 fold, then reduced by 0.01, 0.25, 0.5, and 0.75 fold in the right half only. The left half was paced with a cycle length (CL) of 650 ms until steady-state, followed by premature beats with CLs decremented by 5 ms until reentry or loss of capture. In Langendorff blood-perfused porcine hearts (n=6, kg), the circumflex artery was cannulated and Sotalol (220 µm) infused regionally. Epicardial mapping (11x11 electrode grid, 5 mm spacing) was performed across the border between the two vascular beds. AV-block was induced and programmed stimulation (basic CL ms, up to 5 premature beats) was performed from the area with short repolarization. Baseline QT-interval was gradually increased by incremental infusion of Sotalol in the recirculating system. Results: In computer models, reentry resembling stpvt (>3 sec) in pseudo-ecgs occurred when repolarization time between the centers of the model halves differed by ms, and when baseline repolarization times were ms in the left and ms in the right halves. During stpvt, phase singularities

6 Poster Session V S493 moved along the maximal repolarization gradient (>5.97 ms/mm) that interfaced the model halves. In porcine hearts, stpvt (n=7) was possible only in a critical range of baseline QT-prolongation (53-65% of the CL) and with repolarization gradients 9-27% of the CL. Double frequency potentials occurred at the interface between the vascular beds. Conclusion: stpvts are inducible only when a critical range of repolarization heterogeneity exists in the presence of moderate QT-prolongation, and depend on reentrant pathways that form at regions with maximal repolarization gradient. B-PO CONDUCTIVE POLYMERS AFFECT MYOCARDIAL CONDUCTION VELOCITY BUT ARE NOT PRO- ARRHYTHMIC Richard Jabbour, Kella Kapnisi, Damia Mawad, Balvinder Handa, Catherine Mansfield, Liam Couch, Fillippo Perbellini, Cesare Terracciano, Molly Stevens, Alexander Lyon, Godfrey Smith, Nicholas Peters, Fu Siong Ng and Sian Harding. Imperial College, London, United Kingdom Background: Conducting polymers are being developed as a vehicle for stem cell grafting as they are both flexible and electroactive and may increase safety during the integration of graft with myocardium. Objective: To test the electrophysiological properties of a patch consisting of polyaniline, phytic acid and chitosan, which is relatively stable in oxidized form with retained electro-activity and low surface resistivity. Methods: Ex vivo optical mapping of transmembrane voltage was performed on explanted rabbit hearts(n=8), perfused using the voltage sensitive dye RH237 and blebbistatin. Recordings were conducted before and after attachment of the patch, during ventricular pacing. Arrhythmia susceptibility was then tested using extra-stimulus provocation protocols. Results: Application of the patch to the epicardial surface of heart ex vivo slowed global conduction velocity (70.6 ± 6.8cm/s[without patch] vs 52.0 ± 9.3cm/s[with patch] p=0.0002; Figure). Regional analysis indicated that there was a significant reduction of conduction velocity adjacent to the patch, but no change remote from the patch (42.8 ± 9.6cm/s [around patch] vs 64.5 ± 18.5cm/s [away from patch]; p=< ). There was no significant change in APD 90 (154 ± 11ms[without patch] vs ± 10.5ms[with patch]). Extra-stimulus provocation protocols revealed that the patch did not increase susceptibility to ventricular arrhythmias. Conclusion: The conductive nature of the patch affected myocardial electrophysiology, by slowing conduction in areas adjacent to the patch, though these changes did not appear to be arrhythmogenic. Therefore conductive polymers are safe as a vehicle to aid graft integration. B-PO ELECTROPHYSIOLOGICAL AND STRUCTURAL REMODELING OF THE RIGHT VENTRICLE IN HUMAN ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY David Benoist, PhD, Virginie N. Dubes, PhD Student, Julie Magat, phd, Richard D. Walton, PhD, Cindy Michel, Marion Constantin, Caroline Cros, PhD, Caroline Pascarel-Auclerc, PhD, Fabien Brette, Marine Martinez, Laura Bear, Laura Bear, Line Pourtau, Fanny Vaillant, Philippe Pasdois, PhD, Sébastien Chaigne, Emma Abell, Audrey Semont, Gilles Bru-Mercier, Thomas Hof, Alice Recalde, Bruno Quesson, PhD, Julien Rogier, Josselin Duchateau, MD, MSc, Louis Labrousse, MD, Ruben Coronel, MD, PhD, Michel Haissaguerre, MD, PhD, Meleze Hocini, MD and Olivier Bernus, PhD. L Institut de Rythmologie et Modélisation Cardiaque, Pessac, France, L Institut de Rythmologie et Modélisation Cardiaque, LIRYC- Université de Bordeaux, Pessac, France, IHU LIRYC, Pessac, France, Université de Bordeaux, Pessac, France, Bordeaux- Pessac Cedex, France, LIRYC, Pessac, France, L Institut de Rythmologie et Modélisation Cardiaque LIRYC - Université de Bordeaux, Pessac, France, University of Bordeaux/Inserm U1045/IHU LIRYC, Bordeaux, France, CHU de Bordeaux, Pessac, France, IHU-LIRYC, Pessac, France, Hospital Haut Leveque, Pesac, France, Academic Medical Centre, Amsterdam, Netherlands, Boulogne-Billancourt Cedex, France, CWT Meetings & Events, Mélissa Pernot, Boulogne-Billancourt Cedex, France, IHU LIRYC, Pessac, France Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibro-fatty replacement of the myocardium and associated with arrhythmias and sudden death. However mechanisms underlying these arrhythmias are poorly understood. Objective: To assess the electrophysiological remodeling of the right ventricle (RV) in ARVC. Methods: The RV of a human heart from a transplantation recipient with ARVC was compared to donor hearts (N=2) with no history of cardiac disease. RVs were isolated, perfused via the right coronary and the left anterior descending artery with a modified Krebs-Henseleit solution and electrically-stimulated (1-3Hz). Their electrical activity was optically mapped on the endocardial surface and unipolar electrograms were recorded using transmural needle electrodes. Myocardial structure was assessed by high resolution MRI ( µm isotropic) and histology. Results: Tissue structure was complex and disorganized in the ARVC RV. The epicardium was completely replaced by fat which infiltrated towards the endocardium. Endocardial action potential duration (APD) was prolonged in the ARVC RV free wall (377.4 ms vs ±0.7 ms) and in the RVOT (351.6 ms vs ±6 ms). Rate-dependent (1 to 3Hz) APD shortening was more pronounced in the ARVC RV (-41% vs. -31%). Activation was discontinuous with EGM fractionation across the whole ARVC RV whereas this feature was mainly concealed to the RVOT in donor RVs. In the anterior RV, an unexcitable island of tissue was found and correlated with transmural fibro-fatty infiltrations as detailed on MRI images. A conduction block occurred within the papillary muscle with a 1:1 response at 1Hz, and a 1:8 or no response at higher pacing frequencies which was responsible for large activation and APD gradients. MRI revealed a complex structure at the base of the papillary muscle with fat infiltrations isolating myocardial fibers. Conclusion: ARVC is associated with a profound electrophysiological RV remodeling. APD prolongation, altered rate-dependency and conduction alterations are likely to contribute to arrhythmogenesis in this context.

7 S494 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO OBESITY CAUSES VENTRICULAR IONIC AND STRUCTURAL REMODELING WITH INCREASED ARRHYTHMOGENICITY IN RABBIT MODEL Shin-Huei Liu, MD, Li-Wei Lo, MD, PhD, Yu-Hui Chou, MS, Wei- Lun Lin, MS, Tsung-Ying Tsai, MD, Wen-Han Cheng, Tzu-Yen Peng, Pin-Yi Lin and Shih-Ann Chen, MD. Heart Rhythm Center and Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei, Taiwan Background: Excess weight gain and obesity have been linked with increased prevalence for arrhythmia and sudden cardiac death (SCD). Objective: We aimed to study the electrophysiological characteristics, ventricular remodelings and arrrhythmogenecity in rabbits fed with high fat diet (HFD). Methods: Twelve rabbits, randomized to control and HFD groups. After feeding for 3 months, all rabbits received electrophysiological study and VT/VF inducibility test (Max output with shortest 1:1 cycle length pacing) with a highdensity contact multi-electrode plaque mapping after induction of sustained VT/VF. Ventricular myocardium was harvest for Western blot and Trichrome stain. Results: Body weight was higher in HFD group compared to control group (3.84±0.11 vs ± 0.04 kg, p < 0.001). In HFD group, the ventricular effective refractory periods were longer in LV (188±17 vs. 152±11 ms, p<0.05) and RV (174±16 vs. 148±3 msec, p<0.05), the VF inducibility was higher (61±11 vs. 13±2 %, p<0.01), when compared to those in control group, respectively. The dominant frequency (DF) during VF was similar between 2 groups. Western blot study of ventricular calcium channel protein expressions revealed increased CaV 1.2, NCX and SERCA 2 proteins in HFD group, compared to control group, respectively (Fig A). Advanced fibrosis was noted in HFD group, but not control group (Fig B and C). Conclusion: Obesity causes ventricular remodeling with upregulated calcium handling proteins and advances fibrosis, leading to increased ventricular arrhythmogenecity and risk of sudden cardiac death. B-PO ACUTE AND SHORT-TERM VASCULAR DAMAGE OF CONTACT-FORCE GUIDED RADIOFREQUENCY LESIONS DELIVERED THROUGH THE AORTA AND PULMONARY ARTERY Jose Manuel Alfonso Almazan, MSc, Maria Jesus Garcia- Torrent, PhD, Jorge G. Quintanilla, Santiago Laguna-Castro, MSc, Cruz Rodriguez-Bobada, PhD, Pablo Gonzalez, PhD, Juan Jose Gonzalez-Ferrer, MD, PhD, Victoria Cañadas-Godoy, MD, Nicasio Perez-Castellano, MD, PhD, Julian Villacastin, MD, PhD and David Filgueiras-Rama. Fundacion Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain, Arrhythmia Unit, Cardiovascular Institute, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain Background: Catheter-based radiofrequency (RF) delivery from the root of the aorta (Ao) or pulmonary artery (PA) is necessary to target and ablate certain myocardial substrates. Objective: To study lesion size and microscopic vascular damage after contact-force (CF) guided RF delivery from the Ao and PA, and determine the ablation settings that will provide a high ablation success in combination with a low risk profile. Methods: Twenty-eight pigs underwent in-vivo catheter-based ablation under continuous CF and Lesion Size Index (LSI: Power-CF-Time) monitoring over 60-s RF delivery. Animals were divided into 3 groups as follows: 40W (n=9), 50W (n=10) and 60W (n=9). Up 5 RF lesions were performed at the aortic root and the PA using 3D electro-anatomical guidance. Twentytwo animals were euthanized after ablation to quantify vascular and myocardial lesion sizes and further study the microscopic structural damage using high-resolution multiphoton microscopy. The remaining 6 pigs were used to study vascular resilience and microscopic arterial damage after 3 months of follow-up. Results: A total of 91 RF applications from 28 animals were included for analyses. The incidence of steam-pops correlated with ΔLSI/Δtime ratio (p<0.001) and the baseline power settings (p=0.02). No steam-pops were present with a median ΔLSI/ Δtime ratio<0.14. RF delivery using 50W for less than 22 s did not associate with vascular steam-pops either. Acute vascular collagen and elastin disruption, compared with non-ablated areas, were also significantly associated with RF power, despite no increase in adjacent myocardial lesion size. Areas with myocardial adjacent lesions vs. no overt myocardial damage were associated with CF (19.7±7.1 vs ±6.4 g, respectively, p=0.003) and LSI values (9.3±0.8 vs. 8.6±1.3, respectively, p=0.03). Vascular healing after follow-up (n=6) showed strong aortic resilience after acute increase in left ventricular afterload without structural differences compared with non-ablated areas. Conclusion: ΔLSI/Δtime ratio and LSI values enable to monitor RF delivery to achieve overt RF lesions from the Ao and PA while minimizing the risk of severe acute vascular damage. B-PO LEFT STELLATE GANGLION STIMULATION CAUSES MORE EPICARDIAL THAN ENDOCARDIAL SHORTENING OF REPOLARIZATION IN PIG LEFT VENTRICLE Veronique M.F. Meijborg, PhD, Bas J. Boukens, Master of Science, Michiel J. Janse, MD, PhD, Tobias Opthof, PhD, Siamak Salavatian, PhD, Koji Yoshie, MD, Mohammed A. Swid, Jonathan Hoang, Janki Mistry, Peter Hanna, Olujimi A. Ajijola, MD, PhD, Marmar Vaseghi, MD, FHRS, Jeffrey L. Ardell, PhD, Kalyanam Shivkumar, MD, PhD, FHRS and Ruben Coronel, MD, PhD. Academic Medical Center, Amsterdam, Netherlands, University of Amsterdam, Amsterdam, Netherlands, University of California, Los Angeles, Los Angeles, CA, UCLA Cardiac

8 Poster Session V S495 Arrhythmia Center, Los Angeles, CA, University of California, Los Angeles, Cardiac Arrhythmia Center, Sherman Oaks, CA, UCLA Cardiac Arrhythmia Center, Los Angeles, CA, CA, UCLA, Los Angeles, CA, UCLA Health System, Los Angeles, CA, Academic Medical Centre, Amsterdam, Netherlands Background: Stimulation of the sympathetic nervous system is a trigger for arrhythmias. Commonly observed changes in T wave morphology during sympathetic stimulation suggest increased dispersion of repolarization. Although the effect of sympathetic stimulation on epicardial repolarization patterns has been investigated, the effect on transmural repolarization is unknown. Objective: To measure the effect of left stellate ganglion stimulation (LSGS) on transmural repolarization. Methods: Five pigs were anaesthetized, intubated and ventilated. Following sternotomy, transmural needles (n=24) with 4 electrodes each (4mm interelectrode distance) were inserted in the left ventricular (LV) anterior, lateral and posterior wall. During right atrial pacing (450 ms cycle length), 20 seconds of LSGS (4 Hz, 4 ms, 1-10 ma) was applied. We determined repolarization time (RT) and dispersion (max - min RT) before and during LSGS. We also analyzed the change in RT ( RT= LSGS-baseline). Results: LSGS increased LV end-systolic pressure by 19±1 mmhg (mean±se). LSGS shortened repolarization time both in the subendocardium (270±2 vs 253±5 ms, resp., p=0.001) and subepicardium (278±3 vs 254±6 ms, p=0.001) of the LV wall compared to baseline. The effect of LSGS, however, was larger in the subepicardium than subendocardium leading to disappearance of the transmural gradient in repolarization (epiendo RT) after LSGS (7 vs 1 ms, before vs during, p=0.041). Overall, repolarization shortened more in the posterior wall compared to the anterior wall ( RT 29 vs 3 ms, p=0.054). The maximum total dispersion in repolarization did not change during LSGS (60±3 vs 68±8 ms, p=0.43). Conclusion: Left stellate ganglion stimulation shortens LV repolarization times more in the subepicardium than in the subendocardium. RT shortening is more pronounced in the LV posterior wall than in the LV anterior wall. T wave changes induced by LSGS result from these combined regional and transmural changes in RT. B-PO RENAL SYMPATHETIC DENERVATION INCREASES MRNA EXPRESSION OF KV11.1 AND SUPPRESSES VENTRICULAR ARRHYTHMIAS IN AN EXPERIMENTAL MODEL OF LONG QT 2 SYNDROME Li-Wei Lo, MD, PhD, Yu-Hui Chou, MS, Shin-Huei Liu, MD, Tsai Tsung-Ying, MD, Wen-Han Cheng, Wei-Lun Lin, MS, Tzu- Yen Peng, MS, Pin-Yi Lin, BS and Shih-Ann Chen, MD. Taipei Veterans General Hospital, Taipei, Taiwan Background: Intervention for malignant arrhythmia of Long QT syndrome has been focused on the inhibition of sympathetic activation. Objective: The study aimed to investigate the effect and mechanism of renal artery denervation (RDN) on the Long QT 2 rabbits in preventing ventricular arrhythmia. Methods: 18 rabbits, randomized to control (Q-PCR only), Erythromycin-control (Ery-C) and Erythromycin-RDN (Ery- RDN) Gr. Chemical RDNs were approached through bilateral retroperitoneal flank incisions in Ery-RDN Gr. LQT2 syndrome was simulated by infusion of erythromycin with different concentrations (0, 133, 266 and 400 nmol/kg/min) in Ery-C & Ery-RDN Gr. The mrna expression of ionic channels were measured by Q-PCR in all 3 Gr. Results: Corrected QT interval (QTc), atrial & ventricular ERPs prolonged as concentration increased when compared to baseline in Ery-C & Ery-RDN Gr (FigA to I). The prolongations of QTc & ERPs were less prominent in Ery-RDN, when compared to Ery-C Gr (Fig A to I). There were no difference of AF inducibility in LQT2 rabbits between Ery-C & Ery-RDN Gr. VF inducibility was higher in Ery-C than that in Ery-RDN (38±13 % vs. 12±4%, p=0.02) rabbits. Spontaneous VF (83%) was noted at the highest concentration in Ery-C, but not in Ery-RDN Gr (p=0.015). Increase of of Kv11.1, but not Kv7.1, Kir2.1, Cav1.2, Nav1.5 mrna expressions were noted in Ery-RDN, compared to control and Ery-C, respectively (Table). Conclusion: RDN increases the mrna expression of Kv1.1, and reduces the prolongation of QTc interval and ERPs, therefore, decreased malignant arrhythmia in Long QT2 syndrome, suggesting that RDN may represent a promising antiarrhythmic option in Long QT2 syndrome. B-PO ANGIOTENSIN RECEPTOR NEPRILYSIN INHIBITION PREVENTS HEART FAILURE INDUCED ARRHYTHMOGENESIS THROUGH REVERSE ELECTRICAL REMODELING Li-Wei Lo, MD, PhD, Yu-Hui Chou, MS, Shin-Huei Liu, MD, Tsung-Ying Tsai, MD, Wen-Han Cheng, Wei-Lun Lin, MS, Tzu-Yen Peng, MS, Pin-Yi Lin, MS, Shinya Yamada, MD and Shih-Ann Chen, MD. Taipei Veterans General Hospital, Taipei, Taiwan Background: Sudden cardiac death represents a major cause of death among patients with heart failure (HF). The angiotensin receptor neprilysin inhibitor sacubitril/valsartan (LCZ696, ARNi) reduced mortality in patients with HF. Objective: We aimed to investigate of effects of ARNi to ventricular electrophysiology and arrhythmogenesis in HF model. Methods: Eighteen rabbits, randomized to control, HF and HF-ARNi (Gr 1,2,3) Groups. HF model was created in Group 2 and 3 by rapid ventricular pacing. All rabbits received electrophysiologic study and VT/VF inducibility test (Max output with shortest 1:1 cycle length pacing). Ventricular myocardium was harvested for Western blot and Trichrome stain. Results: Both atrial and ventricular effective refractory periods prolonged in Gr 2, but not Gr 3, when compared to those in Gr 1, respectively. (Fig A &B). The AF WOV (window of vulnerability) was longest in Gr 2 (17±7 sec, p=0.02), longer in Gr 3 (5±2 sec, p=0.03), when compared to that in Gr1. The VF inducibility was highest in Gr 2 (56±2%, p<0.001), and higher in Gr 3(25±2%, p=0.03), when compared to that in Gr 1(18±2%), respectively. Changes of calcium handling proteins (CaV1.2, SERCA and NCX) were observed in Gr 2, and restored to baseline in Gr 3 (FigC). Advanced fibrosis was noted in Gr 2 & 3

9 S496 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 in both ventricles, when compared to Gr 1 (Fig D&E). The ANP levels were highest (3328±611, p<0.01) in Gr 3, higher in Gr 2 (1749±897, p<0.01), when compared to Gr 1 (932±102 pg/ml), respectively. Conclusion: HF increases both atrial and ventricular refractoriness and arrhythmogenecity, and ARNi causes reverse electrical remodeling, prevents atrial, ventricular arrhythmias and sudden death. abstract. 5 studies were eligible for inclusion. 2 RCTs reported on uniform outcomes and were suitable for meta-analysis. The total population comprised anticoagulated participants. Mean age was 71.3 years with a 37.4% female population. Mean follow up was 1.9 years. Use of 5-9 medicines and >9 medicines was associated with significant increases in all-cause mortality, major bleeding and clinically relevant non major bleeding. There was no impact observed on a combined endpoint of stroke or systemic embolism, or intracranial bleeding (see table). Conclusion: Polypharmacy in the AF population is associated with adverse patient outcomes and should be prospectively studied in future research. Medication review provides an opportunity to identify and address medicine-related issues which may improve patient outcomes. Polypharmacy and outcomes in AF All cause mortality Stroke or systemic embolism Major bleeding Clinically relevant non major bleeding Intracranial bleeding 5-9 medicines hazard ratio 95% confidence interval p value >9 medicines hazard ratio 95% confidence interval p value < < < < B-PO B-PO POLYPHARMACY: A RISK MARKER FOR ADVERSE OUTCOMES IN ATRIAL FIBRILLATION Celine Gallagher, BSN, Karin Nyfort-Hansen, PharmD, Debra Rowett, PharmD, Christopher X. Wong, MBBS, PhD, Adrian D. Elliott, PhD, Melissa E. Middeldorp, Rajiv Mahajan, MD, PhD, Dennis H. Lau, MBBS, PhD, Prashanthan Sanders, MBBS, PhD and Jeroen ML. Hendriks, RN, PhD. Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia, Drug and Therapeutics Information Service and University of South Australia, Adelaide, Australia Background: Polypharmacy has been associated with adverse health outcomes, increased healthcare costs and medication burden. Multimorbidity and polypharmacy are common in patients with atrial fibrillation (AF). Objective: To perform a systematic review and meta-analysis examining the impact of polypharmacy on outcomes in the AF population. Methods: PubMed and Embase databases were searched from inception until September 2017 for studies examining the impact of polypharmacy on outcomes in AF including mortality, stroke, TIA, bleeding, hospitalizations, quality of life and falls. Studies were included if they were prospective randomized controlled (RCT) or observational studies, with a minimum of three months follow up and published in English. The most adjusted model in each study was utilized. Results: A total of 717 citations were reviewed by title and HOSPITALIZATIONS DUE TO ATRIAL FIBRILLATION IN AUSTRALIA OVER TWO DECADES: A RELENTLESS RISE Celine Gallagher, BSN, Jeroen ML. Hendriks, RN, PhD, Lynne Giles, BS, Adrian D. Elliott, PhD, Melissa Middeldorp, Rajiv Mahajan, MD, PhD, Dennis H. Lau, MBBS, PhD, Prashanthan Sanders, MBBS, PhD and Christopher X. Wong, MBBS, PhD. Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia, Adelaide Health and Technology Assessment, University of Adelaide, Adelaide, Australia Background: Atrial fibrillation (AF) presents a significant and growing healthcare burden. Much of the burden associated with this condition is related to health care resource utilization, with hospitalizations known to be a significant driver of this. Objective: To characterize rates of hospitalizations due to AF over a 20 year period across all hospitals in Australia, and to compare this to two other common cardiovascular conditions: myocardial infarction (MI) and heart failure (HF). Rates of AF ablation were also assessed, to determine the impact this may have on hospitalizations for AF. Methods: Data were obtained from the Australian Institute of Health and Welfare (AIHW). Hospitalizations with a principal diagnosis of AF, MI or HF were obtained from Time trends in the aggregate yearly numbers of hospitalizations due to each condition were assessed using negative binomial regression models. Data concerning AF ablation were extracted for the years from the procedure database maintained by the AIHW, and analysed applying the same model. Results: Over the 20-year period, there was a relative increase

10 Poster Session V S497 in AF hospitalizations of 295% to a total of in 2013, representing an almost doubling of AF hospitalizations since the beginning of this century. In comparison, MI and HF increased by 73% and 39% to a total of and hospitalizations respectively in Taking into account population changes, there was an annual increase in AF hospitalizations of 5.2% (incidence rate ratio [IRR] 1.052; 95% CI ; P<0.001). In contrast, there was only a 2.2% increase per annum for MI [IRR 1.022; 95% CI ; P<0.001] and negligible annual change for HF hospitalizations [IRR 1.000; 95% CI ; P=0.78]. Whilst AF ablation rates significantly increased [IRR 1.24; 95% CI ; P<0.001), the procedure accounted for 2.8% of all hospitalizations due to AF in Conclusion: The burden of hospitalizations due to AF in Australia continues to demonstrate a relentless rise, with the increased use of AF ablation unlikely to significantly contribute to this. This has important implications for healthcare systems worldwide, with new models of care delivery urgently required to stem the rising tide of health care burden due to AF. B-PO DO SOCIOECONOMIC FACTORS INFLUENCE THE OUTCOMES OF RISK FACTOR MANAGEMENT AND FREEDOM OF PATIENTS WITH ATRIAL FIBRILLATION? Melissa E. Middeldorp, Aashray Gupta, Rajeev Pathak, Adrian D. Elliott, PhD, FHRS, Chrishan J. Nalliah, Celine Gallagher, BSN, Jeroen ML. Hendriks, MS, PhD, RN, Dian A. Munawar, MD, Kashif B. Khokhar, MBBS, Anand Thiyagarajah, MBBS, Dominik K. Linz, MD, PhD, Mehrdad Emami, MD, Kadhim Kadhim, MBChB, Ricardo Sadashi Mishima, MD, Rajiv Mahajan, MD, PhD, FHRS, Dennis H. Lau, MBBS, PhD, FHRS and Prashanthan Sanders, MBBS, PhD, FHRS. Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia, Centre for Heart Rhythm Disorders, Adelaide, Australia, Royal Melbourne Hospital, Melbourne, Australia, Centre for Heart Rhythm Disorders, University of Adelaide, Sefton Park, Australia, Centre for Heart Rhythm Disorders - University of Adelaide, Adelaide, Australia, Centre of Heart Rhythm Disorders, Forestville, Australia, Royal Adelaide Hospital, Centre of Rythm Disorders, Adelaide, Australia, University of Adelaide, Beaumont, SA, Australia, University of Adelaide, Adelaide, SA, Australia, University of Adelaide, Unley, SA, Australia, Adelaide, SA, Australia, Cardiology, Beaumont, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia Background: Patients undergoing risk factor management and weight loss have been shown to improve atrial fibrillation (AF) outcomes. It has been postulated that socioeconomic and lifestyle factors may influence the outcomes of patients with AF and therefore the outcome of their attendance in a risk factor management. Objective: To better understand the impact of socioeconomic factors in risk factor management we evaluated the difference between patients based on the degree of weight loss they achieved or final AF freedom. Methods: Of 355 patients undergoing risk factor management, 319 patients undertook completion of a questionnaire relating to education, employment, income and family background. This was compared with their socioeconomic status (SES) rankings from the Australian Bureau of Statistics. SES was grouped by degree of economic level as LOW, MEDIUM and HIGH. Patients were grouped based on the degree of weight loss (WL) Group 1 (<3%), Group 2 (3-9%) and Group 3 (>10%). AF freedom was ascertained after years of follow-up. Results: There was no difference seen between groups based on degree of WL, for SES (p-0.59), income (p-0.81), higher education (p-0.56), full-time employment (p-0.36), or retirement status (p-0.36). The proportion of patients free from AF at final follow-up showed no significant difference by income (p- 0.48), higher education (p-0.49), full-time employment (p-0.94), retirement (p-0.37) or number of hours worked per week (p- 0.29). However, AF freedom was significantly lower in patients in the middle SES category (OR 0.52, 95% CI: ) compared to high or low SES classes. Conclusion: Regardless of the many different factors in socioeconomic factors assessed in our study, we were unable to demonstrate any specific factor associated with magnitude of weight loss or freedom from AF. These findings highlight that achieving risk factor control is independent of socioeconomic factors. B-PO STANDARD ICD PROGRAMMING IN VENTRICULAR ASSIST DEVICE PATIENTS IS ASSOCIATED WITH INFREQUENT SUCCESS OF ATP AND A HIGH INCIDENCE OF SHOCKS Julie B. Shea, Lara Coakley, CNP, Akshay S. Desai, MD and Bruce A. Koplan, MD, MPH, FHRS. Brigham and Women s Hospital, Cardiovascular Division, Boston, MA, Brigham and Women s Hospital, Boston, MA, Brigham and Women s Hospital Cardiac Arrhythmia Service, Boston, MA Background: Little is known about the optimal programming of Implantable Cardioverter Defibrillators (ICD) in patients (pts) with a Ventricular Assist Devices (VAD), particularly with regards to patient outcomes. Objective: To identify current programming practices in VAD patients and how this may impact patient outcomes. Methods: All VAD patients currently followed at our institution were included. Data regarding demographics, ICD programming and arrhythmia events were included in the data base. Results: A total of 58 VAD pts were included - mean age 61 yrs, 82% male. A total of 34 patients were included in the analysis (18 with no ICD/CRTD, 3 with PPM/CRT-P, 3 ICDs off- were excluded). Sixty eight percent (23/34) of patients were programmed a single therapy zone with ATP before/during charging and first shock maximum energy. The remaining patients had tailored programming. The mean rate cutoff for therapy was 207 bpm (range bpm) and the mean VF number of intervals to detect (NID) was 23 (range ). Appropriate ATP therapy occurred in 8% (3/34) and 35% (12/34) received one or more appropriate shocks. Inappropriate therapy occurred in 12% (4/34) due to AT/AF with rapid rate. Of the patients with CRTD systems (17/34, 50%), 12% (4/34) had the LV lead turned off. Conclusion: Current ICD/CRTD programming in our VAD cohort involves single zone of therapy with ATP in the majority. With these settings ATP is only successful 1/5 of the time and the majority of ventricular arrhythmias require ICD shock. Both appropriate and inappropriate therapy rates mirror that of the general ICD patient population. These findings should be considered in decision making involving this population. B-PO CONTACT FORCE SENSING CATHETERS IN ATRIAL FIBRILLATION ABLATION: A META-ANALYSIS OR RANDOMIZED CONTROLLED STUDIES Thira Rattanakosit, BSc, Dennis H. Lau, MBBS, PhD, FHRS, Thomas A. Agbaedeng, BBS, Dominik K. Linz, MD, PhD, Prashanthan Sanders, MBBS, PhD, FHRS and Rajiv Mahajan,

11 S498 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 MD, PhD, FHRS. Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute and the University of Adelaide, Adelaide, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Centre for Heart Rhythm Disorders, The University of Adelaide, South Australian, Adelaide, SA, Australia, University of Adelaide, Adelaide, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia, Cardiology, Beaumont, Australia Background: Pulmonary Vein Isolation (PVI) is the standard treatment for atrial fibrillation (AF). However, incomplete isolation of the PV causes AF recurrence. It has been advised that the use of contact force (CF) catheters results in more effective ablation lesions and better outcomes. Objective: To compare the success rate of CF-sensing catheter to standard ablation catheter in meta-analysis. Methods: A literature search, in English, was conducted on Ovid MEDLINE, Embase and PubMed with the key words Radiofrequency Catheter Ablation, Contact Force, Lesion Formation and Atrial Fibrillation up to August Studies evaluating comparison of CF vs standard ablation and aspects such as AF recurrence, procedure and fluoroscopy time were included. Included studies were pooled in a random-effects meta-analysis and reported as risk ratio (RR) or standardised mean difference (SMD). Results: After exclusion, a total of 4 Randomised Controlled Trials were included in the combined analyses with 417 participants. A mean follow-up of 10.2±0.8 months, recurrent AF occurred in 30.5% of the patients treated with CF-guided PVI as compared to patients in the non-guided ablation arm with 30.6% (p=0.87). Heterogeneity assessment showed effect size estimates in all 3 trials were well matched. CF-guided ablation did not differ significantly from standard catheter with respect to fluoroscopy time, p=ns or total procedure time, p=ns. Conclusion: CF-sensing catheter ablation technology neither reduces fluoroscopy or procedure time nor does it improve AF freedom ablations. Noteworthy, the present meta-analysis should be interpreted with caution due to apparent small number of participants. B-PO ADHERENCE TO ATRIAL FIBRILLATION ANTICOAGULATION GUIDELINES Amanda K. Kristofik, DNP, NP, Whitney Adams, BSN, DNP, CRNP, Andrew Althouse, PhD, Michael Dorff, MHA, Evan C. Adelstein, MD, FHRS, Gur C. Adhar, MD, William W. Barrington, MD, FHRS, Raveen R. Bazaz, MD, Krishna Kancharla, Andrew H. Voigt, MD, Norman C. Wang, MD, FHRS, Samir F. Saba, MD, FHRS and Sandeep K. Jain, MD, FHRS. Center for Atrial Fibrillation, Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, North Huntingdon, PA, University of Pittsburgh Medical Center, Pittsburgh, PA, Univ of Pittsburgh School of Medicine, Pittsburgh, PA, University of Pittsburgh, Sewickley, PA, UPMC Cardiovascular Institute, Pittsburgh, PA, Univ of Pittsburgh Medical Center, Pittsburgh, PA, UPP Cardiovascular Institute, Wexford, PA Background: Atrial fibrillation (AF) is an increasingly prevalent condition due to the aging population. The most significant morbidity is that of stroke risk. Appropriate prescription of guideline directed anticoagulation therapy based on CHA 2 DS 2 - VASc score is variable in the community. Objective: We sought to evaluate the impact of a dedicated Center for AF on the use of appropriate guideline-directed anticoagulation in this population. Methods: The University of Pittsburgh Center for Atrial Fibrillation was established with the goal of providing comprehensive and individualized care and education to patients with atrial fibrillation. Patients were referred to the Center for AF by general practitioners, cardiologists, and self-referrals. During the initial office visit, comprehensive education was provided by an Advanced Practice Registered Nurse including calculation of a CHA 2 DS 2 -VASc score and discussion surrounding annual stroke risk. Treatment plans were formulated in collaboration with an electrophysiologist. Results: A total of 356 consecutive patients (mean age 65.1 ± 11.1 years; 35.7% female) were treated in the Center for AF from 2015 through 2017, 67% of which were referred by cardiologists. A CHA 2 DS 2 -Vasc score 2 was calculated on 235 patients (mean age 69.4 ± 9.5 years; 54% female). Of these, 187 (80%) were appropriately anticoagulated prior to referral. Anticoagulation was changed (initiation or dose adjustment) to meet guidelines in 31 patients (13.1%) for a total of 93.1% properly anticoagulated after visiting the Center for AF. In patients with a CHA 2 DS 2 -VASc score=0, 29/66 (44%) presented on full anticoagulation. Conclusion: A specialized Center for AF addresses a need for personalized AF treatment including assessing risk of stroke and appropriateness of anticoagulation. At time of initial evaluation, only 80% of patients with a CHA 2 DS 2 -VASc score of 2 were anticoagulated and the regimen was altered in 13.1% of these patients. Additionally, a considerable number of patients were over anticoagulated. Further evaluation of the impact of a specialized Center for AF on patient outcomes as they pertain to CVA is warranted. B-PO PRE-EMPTIVE PATENT FORAMEN OVALE CLOSURE IN A PATIENT UNDERGOING LEAD EXTRACTION DUE TO SEPTIC SHOCK AND ENDOCARDITIS Jill Triphan, RN, BSN, Anne Barnett, PA, Micah J. Roberts, BS, DO, Graham Adsit, MD, Amanda Breuer, BS, EMT, PAC and Miguel A. Leal, MD, FHRS. UW Hospital and Clnics, Madison, WI, University of Wisconsin-Madiso, Oregon, WI, University of California San Francisco-Fresno Cardiovascular Disease Fellowship, Verona, WI, UW Health - Cardiovascular Medicine,

12 Poster Session V S499 Cambridge, WI, Madison, WI, University of Wisconsin, Madison, WI Background: The occurrence of distal embolization during lead extraction procedures may lead to significant complications, especially in patients with a patent foramen ovale (PFO) or an atrial septal defect (ASD). Objective: N/A Methods: We report a complex case that involved an acutely ill patient with history of quadriplegia due to a prior motor vehicle accident, neurogenic bladder requiring frequent intermittent catheterization, non-ischemic cardiomyopathy, atrial fibrillation and a previous defibrillator (ICD) implant, subsequently followed by an upgrade to a biventricular ICD system. Results: The patient was diagnosed with septic shock requiring vasoactive medications, acute renal failure and Staphylococcus bacteremia. Transthoracic echocardiography revealed large soft tissue densities adherent to the endovascular leads, as well as the tricuspid and pulmonic valves. A CT scan of the chest indicated multiple septic emboli involving both lungs. In addition, the patient exhibited hypoxia and a significant right-to-left intracardiac shunt in the setting of a large PFO. After Cardiovascular Surgery felt that the patient presented a prohibitively high risk for open surgical repair, Electrophysiology was consulted for percutaneous system (device and leads) extraction. In order to mitigate the risk of systemic embolization, prior to the lead extraction procedure a 25-mm Amplatzer septal occluder device was successfully placed, achieving adequate closure of the PFO. In the same procedural setting, all four existing endovascular leads were then successfully extracted in their entirety with the assistance of a rotating mechanical dilator sheath. The patient tolerated both procedures without complications. Repeat blood cultures obtained 1 and 3 weeks later remained sterile. The patient eventually underwent a contralateral biventricular ICD implant approximately 1 month following the previous system extraction. Conclusion: Pre-emptive closure of PFO or ASD should be considered to minimize the risk of systemic embolization during lead extraction procedures when large or multiple masses (e.g., vegetations or thrombi) are present. B-PO BRADYCARDIA DUE TO NON-CONDUCTED PREMATURE ATRIAL CONTRACTIONS CURED BY ABLATION OF ECTOPIC FOCI Igino Contrafatto, MD, FHRS, Domenico Caruso, BSc, Antonino Caruso, BSc and Antonio Giordano, MD, PhD. Salus Hospital, Reggio Emilia, Italy, Temple University, Philadelphia, PA Background: Non-conducted premature atrial contractions (PACs) can result in symptomatic bradycardia. When PACs are early and non-conducted, the surface ECG can show only slight distortion of T wave, hiding the buried ectopic P wave, followed by a compensatory pause due to reset of the sinus node; and this can lead to misdiagnosis of sinus bradycardia. Usually, symptoms are predominant at rest and, during exercise, the sinus rate overtakes the ectopic focus and patients can have normal effort tolerance. Afterdepolarization triggered activity is deemed to be the focus mechanism. Objective: Methods: Because of symptomatic bradycardia at rest, four patients were referred for possible pacing therapy. Exercise test and Holter recordings showed adequate rate increase and normal exercise tolerance. Baseline 12 lead ECGs showed some degree of T wave distortion, suspicious for buried and nonconducted ectopic P waves. All four patients underwent mapping and ablation of the atrial foci. Results: Point-to-point mapping showed the earliest ecopic atrial electrograms at the coronary sinus in two patients; at the ostium of the left inferior pulmonary vein in anothe one; and at the lowest part of the tricuspid annulus in the last patient. Radiofrequency ablation at these sites permanently abolished the ectopic foci. Post-Ablation heart rate normalized and all four patients denied any further symptoms of fatigue or ligtheadedness. Conclusion: Bradycardia due to non-conducted PACs is typically more symptomatic at rest and can be misdiagnosed. In these four patients, Ablation of the ectopic foci successfully suppressed the PACs activity and restored normal heart rate. B-PO CARDIAC CONDUCTION ABNORMALITIES ASSOCIATED WITH PACEMAKER IMPLANTATION AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT Stephen Cresse, BSN, Trevor Eisenberg, BS, Carlos Alfonso, MD, Mauricio G. Cohen, MD, Eduardo DeMarchena, MD, Donald Williams, MD and Roger G. Carrillo, MBA, MD, FHRS, CCDS. University of Miami Miller School of Medicine, Miami, FL, Miami Shores, FL Background: Complete heart block is a known complication after transcatheter aortic valve replacement (TAVR), often requiring pacemaker implantation within 24 hours of the procedure. However, clinical markers for delayed progression to complete heart block after TAVR remain unclear. Objective: We sought to examine electrocardiographic data that may correlate with delayed progression to complete heart block and need for pacemaker implantation. Methods: This is a single-center retrospective study of 608 patients who underwent TAVR between April 2008 and June We excluded 164 (27.0%) patients due to having a pacemaker before the procedure or expiring within 24 hours of the procedure (8, 1.3%). To analyze post-procedural EKG data, we excluded an additional 50 (8.2%) patients who received a pacemaker within 24 hours of the procedure. EKG s obtained after the procedure were compared to the pre-procedural EKG to detect new changes. Results: Left bundle branch block, intraventricular conduction delay, left anterior fascicular block, and right bundle branch block were the most commonly seen conduction abnormalities after TAVR (25.1%, 10.9%, 7.5%, and 3.6% respectively). Both left bundle branch block (OR = 2.77 [95% CI: ]) and right bundle branch block (OR = 13.2 [95% CI: ]) carried an increased risk of pacemaker implantation after TAVR. Additionally, PR interval prolongation greater than 40 ms from baseline also carried an increased risk of pacemaker implantation (OR = 3.53 [95% CI: ]). Logistic regression indicated a statistically significant association between PR prolongation and pacemaker implantation (p = 0.004).

13 S500 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Conclusion: Left bundle branch block, right bundle branch block, and PR interval prolongation greater than 40 ms were all associated with delayed progression to complete heart block and need for pacemaker implantation after TAVR. B-PO PERMANENT HIS BUNDLE PACING: A SINGLE CENTER EXPERIENCE FROM AN ACADEMIC MEDICAL CENTER Nicholas J. Serafini, MD, Estefania Oliveros Sole, MD, Ryan Zimberg, BSN, CCRN, RN, Henry D. Huang, MD, Pratik Patel, Kousik Krishnan, MD, FHRS, Richard G. Trohman, MD, FHRS and Parikshit S. Sharma, MD, MPH. Rush University Medical Center, Chicago, IL, University of Illinois Chicago, Chicago, IL, Rush Univ Medical Center, Chicago, IL Background: Permanent HIS bundle pacing (PHBP) has recently gained popularity, with limited data on outcomes except from a few centers. Objective: We sought to review success rates of PHBP, including the ability to recruit bundle branch block (BBB), safety, and outcomes data including LV function, heart failure (HF) and mortality. Methods: 95 patients with an indication for pacing based on current guidelines underwent an attempt at PHBP and were followed prospectively. Results: PHBP was successful in 99% of all attempted cases. Selective (S-HBP) or nonselective HBP (NS-HBP) in those with baseline narrow QRS (<120ms, N=45) and wide QRS (>120ms, N=49) occurred without a significant difference (p=0.097). There was no difference in S-HBP or NS-HBP between LBBB, RBBB, IVCD or narrow QRS. Of patients with a wide QRS, 25 (51%) had complete recruitment (paced QRS < 120ms), 15 (30.6%) had partial recruitment (paced QRS decrease at least 20% and > 120ms), and 9 (18.4%) showed no recruitment. Pacing capture thresholds were similar from implant to follow-up. 5 patients (5.3%) had a threshold increase 2mV. No patients required lead revision. In patients with preexisting heart failure (HF), there was an increase in the LVEF from 29% +/- 14 to 37.75% +/- 18 (p = 0.002) and an improvement in median NYHA class from 3 to 2. Of patients with LVEF < 50% (N=32), 5 (18.2%) had a HF hospitalization in follow up. There were 5 (5.3%) deaths, 1 (1.1%) from a cardiovascular cause. Conclusion: HBP was successful in 99% cases. We successfully recruited (complete or partial) 81.6% of patients with a baseline wide QRS. Clinical follow up demonstrated an improvement in LV function in those with preexisting HF and an improvement in NYHA class. B-PO DEVICE LONGEVITY IN HIS BUNDLE PACING Lina Marcantoni, MD, Francesco Zanon, MD, FHRS, Gianni Pastore, MD, Enrico Baracca, MD, Claudio Picariello, MD, Sara Giatti, MD, Daniela Lanza, MD and Loris Roncon, MD. Santa Maria della Misericordia Hospital, Rovigo, Italy Background: His bundle pacing (HBP) ensures a physiologic ventricular activation and can prevent detrimental effects of right apical pacing. High threshold is one of the main concerns due to the impact on battery. Objective: To evaluate device longevity in a large population of patients treated with HBP during a long-term follow-up. Methods: We retrospectively analyzed 431 patients (mean age 76±8 years; 59%males) with standard indication for pacing treated with selective HBP (52%) or non selective HBP, from 2004 to The pacing indications were: AV block in 50.6% pts, sinus node disease in 20.2%, atrial fibrillation with slow ventricular rate in 26.5%, and HF in 2.8%. Ischemic cardiopathy was present in 102 patients (23.7%), hypertension in 370 patients (85.8%) and diabetes in 116 (27%) pts. Basal mean EF was 57±11%. 37% of patients had pre-implant conduction system disease (LBBB 12.8% pts). The implanted devices were: CRT-P 42%; DR PM 49%; SR PM 9%. A back-up lead was implanted in apex in 56.3% pts. Pacing threshold at implant was 0.8±0.4 ms. Results: 354 patients had at least 1 follow-up visit with available data to evaluate HBP performance.these patients were checked in clinic once a year (no remote monitoring) during a mean time of 5.4±3.5 years. At the end of follow up 317 (89.5%) patients showed persistence of effective HBP with QRS morphology and duration as the basal. Median % of VP was 99% (IQR ) and 89.5% (316) pts showed VP>40%. During follow up device replacement was performed in 161 (45.7%) patients, due to end of life (EOL) in 85% (137) pts. The mean longevity of the devices was 5.7±2.1 years (years to SR-device replacement 4.9±2.2; years to DR-device replacement 6.1±2.3; years to CRT- device replacement 5.5±1.8). It was required to add a back-up lead in 12 (7.8%) pts and to up-grade to CRT in 4 cases. At the end of follow-up pacing threshold was 2.4±1.6V@ 0.8±0.5ms. Lead deficiency with premature interruption of HBP was documented in 48 (13.6%) pts, of which 28 was due to exit block and threshold>5v. The mean EF at the end of follow-up was 60±11%. 24 (7.9%) pts experienced heart failure hospitalizations. Conclusion: HBP is feasible and safe in the clinical practice. Device longevity is good keeping in mind the clinical benefit. B-PO LEADLESS PACEMAKER IMPLANT IN HEMODIALYSIS PATIENTS: EXPERIENCE WITH THE MICRA TRANSCATHETER PACEMAKER Mikhael F. El-Chami, MD, FHRS, Nicolas Clementy, Christophe Garweg, MD, Razali Omar, MD, FHRS, Gabor Z. Duray, MD, Charles C. Gornick, MD, FHRS, Francisco Leyva, Venkata S. Sagi, MD, FHRS, Jonathan P. Piccini, MD, MHS, FHRS, Kyoko Soejima, MD, Kurt Stromberg, MS and Paul R. Roberts, MD. Emory University, School of Medicine, Atlanta, GA, CHU Tours, France, UZ Leuven, Diegem, Belgium, National Heart Institute, Kuala Lumpur, J. W. Goethe University, Dept. of Medicine, Div. of Cardiology, Frankfurt am Main, Germany, Minneapolis Heart Institute, Allina Health, Minneapolis, MN, Department of Cardiology, University of Birmingham, Good Hope Hospital, United Kingdom, Southern Heart Group, Jacksonville, FL, Duke University Medical Center, EP, Durham, NC, Kyorin University School of Medicine, Tokyo, Japan, Medtronic, Mounds View,

14 Poster Session V S501 MN, University Hospital Southampton, Southampton, United Kingdom Background: Leadless pacemakers may be preferred in patients with limited vascular access and high-infection risk, such as patients on hemodialysis. Objective: To report peri-procedural outcomes and intermediate-term follow-up of hemodialysis patients undergoing Micra implant. Methods: Patients on hemodialysis at the time of Micra implant attempt (N=168) from the Micra Transcatheter Pacing (IDE) Study, Continued Access (CA) study, and Post-Approval Registry (PAR) were included in the analysis. Baseline characteristics, peri-procedural outcomes and intermediate-term follow up were summarized. Results: Patients on hemodialysis at the time of Micra implant attempt were on average years old and 60.7% were male. Common co-morbid conditions included hypertension (78%), diabetes (61%), coronary artery disease (38%), and heart failure (24%). The primary pacing indication was associated with AF in 45% of patients and 68% had a condition that the implanting physician felt precluded the use of a transvenous pacemaker. Micra was successfully implanted in 165 patients (98.2%). Reasons for unsuccessful implant included inadequate thresholds (2 patients) and pericardial effusion (1 patient). The median implant time was 27 minutes (IQR: 20-39), with a 6-minute median (IQR: 4-10) fluoroscopy duration. There were 2 procedure-related deaths: 1 due to metabolic acidosis following a prolonged procedure duration in a patient undergoing concomitant atrioventricular nodal ablation and 1 death occurred in a patient who needed surgical repair after perforation during implant and died during hospitalization from sepsis. Average follow-up was 5.2 months (range ). No patients had a device related infection or required device removal because of bacteremia. Conclusion: Leadless pacemakers represent an effective pacing option in this challenging patient population on chronic hemodialysis. The risk of infection appears low with an acceptable safety profile. B-PO SERUM GALECTIN-3 LEVEL AS A PREDICTOR OF ADVERSE OUTCOMES NECESSITATING IMPLANTABLE CARDIOVERTER DEFIBRILLATOR PLACEMENT IN ST- ELEVATION MYOCARDIAL INFARCTION PATIENTS Charl Khalil, MD, Wassim Mosleh, Kevin Frodey, MD, Tanvi Shah, MD, Amira Ibrahim, MD, Milind Chaudhari, MD, PhD, Zaid Al-Jebaje, MD and Umesh C. Sharma, MD, PhD. University at Buffalo, The State University of New York, Buffalo, NY Background: Implantable cardioverter defibrillators (ICD) are used for treatment of patients at risk of sudden cardiac death (SCA) secondary to ventricular tachyarrhythmias. Currently left ventricular ejection fraction (LVEF) is the most reliable indicator for ICD placement. Objective: We investigated the association between galectin-3, a prognostic biomarker implicated in post myocardial infarction (MI) cardiac remodeling, and the development of post MI outcomes necessitating ICD placement. Methods: We prospectively enrolled 96 patients with ST- Elevation MI (STEMI) and percutaneous intervention (PCI). Galectin-3 levels were measured in serum samples obtained hours from presentation. Primary study endpoint was a composite outcome of indications for ICD placement in MI patients as per the definition of ACCF/AHA/HRS guidelines. This was defined as SCA due to ventricular fibrillation (VF) or hemodynamically unstable sustained ventricular tachycardia (VT) > 48 hours post MI or LVEF 35% detected by any diagnostic/therapeutic modality at least 40 days post-mi. Patients with lost follow up or no further EF documentation were included in the negative composite outcome group. Results: On one year follow up, a total of eleven patients were found to have positive primary composite outcome, including nine patients with EF 35%, one patient with SCA due to VF, and one patient with recurrent unstable sustained VT. Galectin-3 levels were significantly higher among patients with positive primary composite outcome as compared to those with negative outcome (16.3 ± 5.39 vs ± 9.27 ng/ml, p= 0.022). Galectin-3 was also found to be an independent predictor of positive composite outcome [Odds ratio= (1.019, 1.258), p= 0.020]. Further analysis showed a statistically significant linear trend (p=0.016) with higher galectin-3 levels (tertile) associated with higher proportion of patients with primary positive composite outcome. Conclusion: Galectin-3 level is a potential predictor of outcomes mandating ICD placement in patients who had STEMI and underwent PCI. Future studies validating its utility for early identification and risk stratification of those patients before developing further LVEF reduction or ventricular tachyarrhythmias are warranted. B-PO ANTIARRYTHMIA DEVICE USE IN MYOTONIC DYSTROPHY POPULATION: A SINGLE CENTER EXPERIENCE Danesh K. Kella, MBBS, Nicolai Grüner-Hegge, Deepak Padmanabhan, Ruben Aguayo, Jose Pardo, MD and Paul A. Friedman, FHRS. Mayo Clinic, Decatur, GA, Cambridge University, Cambridge, United Kingdom, Mayo Clinic, Rochester, MN, University of Chile, Chile, Militar Hospital, Santiago, Chile Background: Previous studies suggest that Myotonic Dystrophy (MD) patients may benefit from implantable cardioverterdefibrillator (ICD) therapy due to high sudden death risk. Objective: To describe the implant rates and the outcomes of permanent pacemaker (PPM) and ICD in the MD population. Methods: All patients referred to Mayo Clinic with clinically or genetically proven type 1 or type 2 MD were reviewed, and the date and type of device implanted were recorded. Rates of death were compared between PPM and ICD groups using the Kaplan- Meier (log rank) test. The association between device implant with mortality was assessed with a Cox model, treating device presence as a time-dependent covariate. Results: The 187 MD patients had a mean age of 35.8 years and 47.1% were male. During follow-up, 43 patients underwent device implantation (44% ICD and 56% PPM); ICD recipients had depressed ventricular function or VT/VF. The cumulative probability of an ICD or PPM implantation was 40% at 15 years. There were total of 21 deaths during median follow-up of 7.44 years for the entire cohort. There was no difference in mortality between device and non-device groups (HR=2.75( ), p=0.17). There was no significant mortality difference in the ICD vs. PPM groups (10 survival of 63% vs 65% p= 0.53; Figure). Conclusion: The device implant rate in our cohort is comparable to previous studies. There was no significant difference in mortality between ICD and PPM groups, suggesting ICD therapy is effective in high risk subsets.

15 S502 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO SINGLE INCISION TECHNIQUE FOR PLACEMENT OF SUBCUTANEOUS IMPLANTABLE CARDIOVERTER DEFIBRILLATORS Yousef Darrat, MD, Francis Benn, MD, Mohsin Salih, MD, Jignesh S. Shah, Kevin W. Parrott, MD, Gustavo X. Morales, MD, John Gurley, MD and Samy C. Elayi, MD, PhD. University of Kentucky, Lexington, KY, Boulder Heart, Longmont, CO, University Of Kentucky, Division of Cardiovascular Medicine, Lexington, KY, University of Kentucky, Lexington, KY, UK Gill Heart Institute, Lexington, KY Background: Subcutaneous Implantable cardioverter defibrillators (S-ICDs) have gained increasing popularity because they offer several benefits while avoiding some of the complications associated with transvenous ICDs. However, while transvenous ICDs require a single surgical incision to implant, subcutaneous defibrillators need at least two. Objective: This study sought out to investigate the feasibility of using a single incision technique to implant S-ICDs. Methods: Patients qualifying for ICDs without the need for pacing were tested for candidacy for S-ICD. Ten patients underwent a single incision technique for S-ICD implant as follows: after a left inframammary incision is made (figure 1A and 1E), the subcutaneous tissue is dissected medially towards the lower sternum. Two sutures are placed in the fascia in the xiphoid area to anchor the lead (figure 1B) and a tunneling tool is used to dissect the tissue to place the lead parallel to the sternum (figure 1C). Subcutaneous tissues are then dissected down the lateral chest wall over the muscle fascia to create the pulse generator pocket in the vicinity of the fifth and sixth intercostal spaces and near the mid-axillary line (figure 1D). Results: A total of 10 patients (5 males and 5 females) successfully underwent S-ICD implantation without acute complications for primary (60%) and secondary prevention. The mean age is /- 15 years. There were no lead dislodgements or inappropriate shocks during follow up. Median duration of follow up is 10.5 months (IQR ). Conclusion: A single incision for S-ICD implantation is feasible and safe in this series without complications during follow-up. B-PO MANAGEMENT OF PHYSIOLOGICAL INTRACARDIAC OVERSENSING WITH THE SECURESENSE TM ALGORITHM Nicolas Welte, MD, Sylvain Ploux, MD, Romain Eschalier, MD, PhD, Marc Strik, MD, Pierre Mondoly, MD, Philippe Ritter, MD, Michel Haissaguerre, MD, PhD and Pierre Bordachar, MD, PhD. Bordeaux University Hospital (CHU) and IHU Liryc, Electrophysiology and Heart Modeling Institute, Pessac, France, Pessac, France, Bordeaux University Hospital (CHU), Pessac, France, Clermont-Ferrand University Hospital, Clermont Ferrand, France, Physiology, Aubel, Belgium, Cardiovascular and Metabolic Pole, Rangueil Hospital, Toulouse, France, University Hopital of Bordeau, Hopital Du Haut Leveque, Pessac 33600, France, Boulogne-Billancourt Cedex, France, CHU Bordeaux, Bordeaux, France Background: The SecureSense algorithm (Abbott) has initially been designed to prevent inappropriate therapies for lead dysfunction. However, it may also be very promising 1) for allowing early diagnosis of intra-cardiac oversensing (P, R or T wave) and 2) for modifying the management in this context (no need for lead revision or for altering the sensitivity). Objective: 1) To assess the incidence of intra-cardiac oversensing in a large population of patients implanted with recent ICDs; 2) To assess the accuracy of the SecureSense algorithm to diagnose intra-cardiac oversensing; 3) To evaluate the capacity of the algorithm to prevent inappropriate therapies on the long-term. Methods: We included 486 patients in 3 different centers with an Abbott device followed by remote monitoring. In patients with intra-cardiac oversensing, a corrective measure was applied (lead revision or reprogramming of sensitivity parameters) in the following conditions: lead dislodgment or failure, drop in biventricular pacing in CRT patients, episode of prolonged oversensing with completion of the VT/VF counters. In the other cases, a conservative strategy leaving the SecureSense algorithm running on the long term was privileged. Results: The SecureSense algorithm initially correctly identified the 30 patients (6.2%) with physiological oversensing without delivery of inappropriate therapy: P-wave oversensing was diagnosed in 10 patients (2.1%), R-wave double counting in 2 (0.4%) and T-wave oversensing in 18 (3.7%). A corrective measure was applied in 10 patients (33%). In the remaining 20 patients, the oversensing was tolerated with a long-lasting solicitation of the algorithm. The mean follow-up after diagnosis was 20±14 months without delivery of inappropriate therapy. The oversensing alert remained isolated in 14 patients (47%). The

16 Poster Session V S503 recurrence rates of an oversensing alert were 20%, 50% and 72% in case of P-wave, R-wave and T-wave oversensing. Conclusion: Oversensing of intra-cardiac signals is infrequent with the latest ICDs generation and are early diagnosed by the SecureSense algorithm. In selected patient, a long-lasting solicitation of the algorithm is a safe alternative to sensing correction without increased risk of inappropriate therapy. B-PO A NOVEL PROGRAMMING LANGUAGE TO REDUCE ENERGY CONSUMPTION BY ARRHYTHMIA MONITORING ALGORITHMS IN IMPLANTABLE CARDIOVERTER- DEFIBRILLATORS Houssam Abbas, PhD, Konstantinos Mamouras, PhD, Alena Rodionova, MSc, Rajeev Alur, PhD, Jackson J. Liang, DO, Sanjay Dixit, MD, FHRS and Rahul Mangharam, PhD. University of Pennsylvania, Philadelphia, PA, Hospital of the University of Pennsylvania, Philadelphia, PA, Hosp. of Univ of Pennsylvania, Wynnewood, PA Background: Arrhythmia Detection Algorithms (ADA) employed by devices such as Implantable Cardioverter Defibrillators (ICD) and Implantable Loop Recorders continuously monitor the rhythm to detect arrhythmias. ADAs are a major consumer of battery power. For a given hardware, power consumption depends on the Programming Language (PL) used to code the ADA. The present PL approach, which utilizes a database of electrograms to estimate maximum power consumption, is unreliable and not very flexible. Objective: To introduce a novel PL which allows estimation of ADA maximum power consumption early in the device design process. We hypothesize that this approach should minimize power consumption without compromising detection ability. Methods: We used Quantitative Regular Expressions (QRE), which is a PL that can process large amounts of data in a small amount of time, to code ADAs. Using QRE, guaranteed estimates of maximum power consumption can be obtained. We coded three variations of an ADA from a single ICD vendor (Boston Scientific) in the QRE language: Baseline version, a version without the Onset discriminator (NoOnset), and a version with Duration set to 1sec (ShortD). We computed estimates of maximum power consumption for the three versions by running the code on a standard laptop. Each version was run a 100 times. Results: ADA Baseline has the highest power consumption (3.37e-5 Joules per calculation), and ShortD the lowest (1.1337e-5 Joules per calculation, p-value of difference = 0.01). NoOnset has almost identical power consumption to Baseline (3.2637e-5 Joules per calculation, p-value of difference with Baseline = 0.45). Conclusion: A novel programming language for ADAs allows reliable and early comparison of maximum power consumption between ADAs. Results suggest that patients who might benefit from the Onset discriminator should have it turned on by default with minimal loss in device longevity. Shortening the Duration increases longevity significantly but is known to increase the rate of inappropriate therapy. The QRE language lets engineers make these power comparisons early to better improve battery lifetime. B-PO WAVELET HISTORY BUFFER INDICATES LONG TERM STABILITY OF ELECTROGRAM Karen Kleckner, MS, Mark L. Brown, PhD and Troy E. Jackson, MS. Medtronic, Mounds View, MN Background: The Wavelet Algorithm is a supraventricular (SVT) and ventricular tachycardia (VT) discriminator that compares the morphology of a baseline rhythm QRS template to that of tachycardia. ICDs automatically create new baseline templates when they fail to match normal rhythm, and store information for the past 98 template updates. Objective: To characterize the stability over time of the electrogram (EGM) morphology used in rhythm discrimination. Methods: A retrospective analysis using the US CareLink database was performed. Subjects were included if they had been implanted with a Viva/Evera device and followed for at least one year, had Wavelet programmed to On/Monitor and had at least one SVT episode. The template history data was queried to obtain the template update frequency and baseline QRS morphology, and the SVT episode log was queried to obtain SVT timestamp and match percentages. Results: template history buffer entries were available for 7887 of the subjects in the dataset. Most subjects (78%) have 1-5 template updates per year, but a substantial number (6%) have over 100 updates per year. Subjects with frequent updates typically have smaller QRS and/or dual-peaked QRS waveforms. Subjects with templates created more than 1 week prior to an SVT (N=15696) had 86% match versus 53% for templates within 1 week (N=1251). 69% of subjects with a weekly or greater template update frequency have peak-peak QRS amplitude < 30% of the EGM range. Subjects with smaller EGMs would benefit from adjustments to the EGM range to improve resolution of EGM sampling and stability to matching normal rhythm. Subjects with dual-peaked QRS waveforms may benefit from selecting an alternative EGM vector. Conclusion: Most subjects have a baseline QRS morphology that is stable over time. Frequent template updates are associated with smaller amplitude and/or dual peaked EGMs, which may be addressed by simple programming changes to improve rhythm discrimination. B-PO USEFULNESS OF THE NOVEL TUBE-EXERCISE TEST TO PREDICT MYOPOTENTIAL INTERFERENCE IN PATIENTS WITH SUBCUTANEOUS IMPLANTABLE CARDIOVERTER- DEFIBRILLATOR Yuji Ishida, MD, Shingo Sasaki, MD, Masaomi Kimura, 1, Daisuke Horiuchi, MD, PhD, Taihei Itoh, M.D., Takahiko Kinjo, Yoshihiro Shoji, Yuichi Toyama and Hirofumi Tomita. Hirosaki University Graduate School of Medicine, Hirosaki, Japan, Department of Advanced Management of Cardiac Arrhythmias Hirosaki University School of Medicine, Aomori, Japan, Hirosaki University, Hirosaki, Japan, Hirosaki University Gradyate School, Japan Background: The most common cause of inappropriate shock (IAS) of the subcutaneous implantable cardioverter-defibrillator (S-ICD) is T-wave oversensing (TWOS) and myopotential interference (MI). TWOS can be solved by filtering. However, there are few reports for IAS caused by MI. Objective: The purpose of this study was to assess the efficacy of MI prediction by an originally developed tube-exercise test (TET). Methods: We experienced 47 patients who underwent S-ICD implantation between February 2016 and November Of them, 31 patients [24 men, median age 60 (IQR 45-66) years, median BMI 25.3 (IQR )] took TET. TET consists of three different exercises using exercise-tube to assess the risk of MI. In each exercise the patient periodically moves the upper limbs. During exercise, we confirm whether myopotential occurs in subcutaneous electrogram (S-ECG). We judged positive in TET when MI was observed in S-ECG annotated S marker

17 S504 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 during exercise at least one sensing vector. Results: Eleven patients (35%) were positive in TET. During a median follow-up period of 350 (IQR ) days, four patients (13%) experienced IAS due to MI (N=3) or TWOS (N=1). All the patients in IAS due to MI (N=3) were positive in TET. MI was confirmed in sensing vector at the time of IAS in all cases. There was no IAS in patients with negative TET. The sensitivity and specificity of the TET was 100% and 71%, respectively, and its positive and negative predictive value was 27% and 100%, respectively. Conclusion: These findings indicate that our original TET may be useful for predicting sensing vector leading to future MI and for avoiding IAS by optimal setting. are associated with low first shock efficacy and may warrant revaluation of the system position. B-PO HIGH VOLTAGE IMPEDANCE DETERMINES SUBCUTANEOUS IMPLANTABLE DEFIBRILLATOR VENTRICULAR FIBRILLATION CONVERSION SUCCESS Anish K. Amin, MD, Michael R. Gold, MD, PhD, FHRS, Martin C. Burke, DO, Bradley P. Knight, MD, FHRS, Steven J. Kalbfleisch, MD, FHRS, Toshimasa Okabe, Elizabeth Duffy, MS, Michael Husby, MS, Wyatt K. Stahl, Moutie R. Rajjoub, Mahmoud Houmsse, MD, Jaret Tyler, MD, Emile G. Daoud, MD, FHRS, John D. Hummel, MD, FHRS, Ralph Sayre Augostini, MD, FHRS and Raul Weiss, MD, FHRS, CCDS. Riverside Methodist Hospital, Upper Arlington, OH, Medical Univ of South Carolina, Charleston, SC, CorVita Science Foundation, Chicago, IL, Northwestern University, Feinberg School of Medicine, Chicago, IL, The Ohio State University, Columbus, OH, The Ohio State University Wexner Medical Center, Dublin, OH, Boston Scientific, St Paul, MN, Boston Scientific, St. Paul, MN, The Ohio State University Medical Center, Columbus, OH, Ohio State University, Department of Cardiovascular Medicine, Columbus, OH, The Ohio State University Medical Center, Div of Cardiovascular Medicine, Columbus, OH, Ohio State Univ, Div of Cardiovascular Medicine, Columbus, OH, OSU Div of Cardiovascular Medicine, Columbus, OH, Ohio State Univ Medical Center, Div of Cardiovascular Medicine, Columbus, OH Background: The Subcutaneous (SQ) Implantable Cardioverter Defibrillator (ICD) requires defibrillation testing at the time of implantation. Predictors of defibrillation success have not yet been identified. We hypothesized that high voltage impedance is associated with probability of success. Objective: We hypothesized that high voltage impedance is associated with probability of success. Methods: Data from 286 patients participating in the Investigational Device Exemption (IDE) study with acute conversion testing at 65 J in the final implant position and impedance data available were included in this analysis. Ventricular Fibrillation (VF) inductions were reviewed and successes or failures for conversion testing were evaluated against shock impedances. Successful conversions at 65 joules were recorded in 576 inductions in 279 patients, and 69 defibrillation failures were recorded in 46 unique patients. Results: 645 conversion tests were conducted at 65J with a conversion efficacy of 89.3%. The average impedance across all tests was 77 ohms (range ). Mean impedance of successful conversions was 75 ohms compared to 89 ohms in failed conversions (p <.0001). Success of VF conversion was inversely related to shock impedance (Figure). Impedances less than 110 ohms were associated with a 91% (537/590) conversion success rate while impedances greater than 110 ohms were associated with a 71% (39/55) conversion success rate (p <.0001). Conclusion: SQ ICD high voltage impedance is inversely related to conversion success. Impedances over 110 Ohms B-PO WHAT IS THE VALUE OF ISCHEMIC EVALUATION AFTER APPROPRIATE CRT-DEFIBRILLATOR SHOCKS? Evan C. Adelstein, MD, FHRS, Raveen Bazaz, MD, Sandeep K. Jain, MD, FHRS, Norman C. Wang, MD, FHRS and Samir F. Saba, MD, FHRS. University of Pittsburgh Medical Center, Pittsburgh, PA, UPP Cardiovascular Institute, Wexford, PA, Univ of Pittsburgh Medical Center, Pittsburgh, PA Background: Utility of testing for ischemia as a trigger of CRTdefibrillator (CRT-D) shocks in pts with known CAD is not well known. Objective: To determine if testing for ischemia at first hospitalization for CRT-D shocks is associated with reduced risk of subsequent shocks in pts with known CAD. Methods: We examined the clinical course of all 133 CRT-D pts with CAD who were hospitalized between 9/00 and 4/17 with appropriate CRT-D shock(s) and without clinical MI from a prospectively maintained database in a large multi-hospital network. Results: We studied 133 pts (98 monomorphic VT, 35 polymorphic VT/VF), including 120 men, median age 69 and QRS duration 169 ms, 39 LBBB, 55 IVCD, 11 RBBB, and 28 pacer-dependent. Ischemic evaluation was done in 60 pts, including stress myocardial perfusion imaging (MPI; n=28) or coronary angiography (n=32). Pts with or without ischemic evaluation were similar, but more pts without ischemic evaluation received anti-arrhythmic therapy (85% vs. 43%; p<0.01) All stress MPI showed scar ± minimal peri-infarct ischemia; none led to angiography. Eight pts received PCI, 5 with monomorphic VT and 3 polymorphic VT/VF. During 22 mos followup, 64 pts (48%) had recurrent shock(s). There was no difference in time to recurrent shock based on ischemic evaluation (HR 1.4, 95% CI ; p=0.2) or testing modality (angiography vs. MPI; HR 1.5, 95% CI ; p=0.2). Recurrent shocks occurred in 7 of 8 pts who received PCI, including all 5 with monomorphic VT. Conclusion: In pts with CAD hospitalized with appropriate CRT-D shock(s), ischemic evaluation has low diagnostic yield, is not associated with lower recurrent shock risk, and may discourage anti-arrhythmic therapies.

18 Poster Session V S505 difference was observed between one-lead ECG and PPG in diagnosing AF. This device enables the potential to detect and diagnose AF in patients with paroxysmal of unknown episodes of AF. B-PO B-PO DIAGNOSIS OF ATRIAL FIBRILLATION BASED ON A PPG SIGNAL COMPARED TO ONE LEAD ECG Thijs Vandenberk, MSc, Christophe Mortelmans, MD, Ruth Van Haelst, MD, Gertjan Van Schelvergem, MSc, Caroline Pelckmans, Valerie Storms, PhD, Inge M. Thijs, PhD, Bert Vaes, MD, PhD and Pieter M. Vandervoort, MD, PhD. Mobile Health Unit, Faculty of Medicine and Life Sciences, Hasselt University, Hasselt, Belgium, Department of Public Health and Primary Care, KU Leuven (KUL), Leuven, Belgium Background: Atrial Fibrillation (AF) is the most common cardiac arrhythmia with 33.5 million people worldwide affected. AF has many health consequences, such as stroke and heart failure. The diagnoses of AF is nowadays confirmed by the cardiologist based on the 12-lead electrocardiogram. However, studies on ischaemic stroke demonstrate that AF is frequently diagnosed during and after an event. Here mobile monitoring solutions are able to detect AF outside face-to-face visits. By using a smartphone with a custom-made application (FibriCheck ), the cardiac pulse rate can be measured anytime and anywhere by the PPG-signal in the tip of the finger using the smartphone camera. Objective: To goal of this research project is to study the capability of diagnosing atrial fibrillation based on the PPG waveform compared to single lead ECG and the gold standard 12 lead ECG. Methods: A double-blind, randomised, prospective study was performed. A convenience sample of patients with a history of AF was invited to participate in the study. The PPG and single lead ECG were obtained simultaneous during a 60 seconds time interval. These measurements were followed by a 12 lead ECG. The visual signal of the simultaneous measured PPG and onelead ECG were selected for diagnosis by a cardiologist. These files included AF, sinus rhythms, bad signal measurement and other (sinus arrhythmia, atrial flutter, etc.) measurements. Two cardiologists were asked to review half of the files. The diagnosis of the PPG and one-lead ECG signals were compared to the diagnosis of the 12-lead ECG. Results: 344 pairs of PPG, one-lead ECG and 12-lead ECG signals were reviewed by cardiologists. Out of the 12-lead ECG files, 173 were diagnosed as AF. Averaged results for good signal quality showed a PPG sensitivity rate of 0.97 and a specificity rate of 0.99 compared to a sensitivity rate of 0.98 and a specificity rate of 0.98 for the one-lead ECG. Conclusion: The use of a smartphone application for AF patients results in an almost exact accuracy for the diagnose of this heart rhythm disorder. Based on expert review no significant DIAGNOSTIC ACCURACY OF A SMARTPHONE-BASED ATRIAL FIBRILLATION DETECTION ALGORITHM Isma Nusrat Javed, MD, MBBS, Nazir Ahmad, MD, MBBS, David Albert, MD and Stavros Stavrakis, MD, PhD. University of Oklahoma Health Sciences Center, Oklahoma City, OK, Saint Anthony Hospital, Oklahoma City, OK, AliveCor Inc., Oklahoma City, OK, University of Oklahoma Health Sciences Center, Cardiology, Oklahoma City, OK Background: Smartphone-based single-lead ECG devices have enhanced the feasibility of diagnosis and monitoring of arrhythmias, including atrial fibrillation (AF). The Kardia mobile ECG device is an FDA approved smartphone-based, single lead device, with an automated algorithm to detect AF, based on RR irregularity and absence of P waves. Objective: We examined the diagnostic accuracy of the Kardia Mobile algorithm for the diagnosis of AF in patients with paroxysmal AF. Methods: Twenty nine patients with paroxysmal AF and low CHADS2-VASc score were instructed to transmit a 30-second ECG every day and when experiencing symptoms for a median period of 20 months. The ECGs were transmitted to a secure server and the diagnosis was manually confirmed by 2 physicians. The sensitivity and specificity of the automated algorithm for the diagnosis of AF were compared against the physician interpretation as the gold standard. Results: Over a median follow up of 20 months, 20 patients failed to submit a daily ECG at least once (median 3 failed submissions). A total of 14,998 ECGs were recorded. AF was diagnosed in 715 (5%) ECGs, while 1549 (10%) were deemed undetermined by the device. Overall, the kappa coefficient of agreement was 0.89 (95% confidence intervals 0.88 to 0.91; p<0.0001), indicating excellent agreement between the 2 methods. The device had a 99% sensitivity and 98% sensitivity for diagnosing AF. When the undetermined ECGs were treated as possible AF in the analysis, representing the worst case scenario, the specificity dropped to 87%, while the sensitivity was maintained at 99%. Conclusion: The Kardia mobile ECG device provides excellent diagnostic accuracy in diagnosing AF, supporting the notion that such a device can be used for AF screening. In this setting, a high sensitivity in diagnosing AF will allow physicians to review only those recordings that are classified by the device as AF, in order to decrease the burden of having to review every transmitted ECG recording. The diagnostic accuracy of this single lead ECG device is critically dependent on high-quality signals. Thus, efforts should be directed towards patient education to acquire high-quality signals to optimize the performance of the device. B-PO ARE EXISTING PACEMAKER/ICD PATIENTS CANDIDATES FOR A COMPLETELY EXTRACARDIAC LEAD PLACEMENT? Martin C. Burke, DO, Alan Marcovecchio, MS, Rick Sanghera and Richard Wasley, MD. CorVita Science Foundation, Chicago, IL, AtaCor Medical, Inc., San Clemente, CA Background: A completely extracardiac pacing/defibrillation lead may eliminate complications related to vascular access,

19 S506 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 endocardial device placement and lead extraction challenges. The feasibility of placing an extracardiac lead has been previously explored with promising results in a limited number of subjects. The extracardiac lead was placed into the Intracostal Space (IS), defined as the space between the inner surface of the ribs and pericardium. The IS was accessed through Intercostal Space (ICS) 4, 5 or 6, near the left sternal margin, over the cardiac notch of the left lung. However, the impact of anatomical variability requires further evaluation. Objective: To characterize thoracic and other relevant anatomic variations of the IS via an ICS in pacemaker (PM) / ICD patients with 3-dimensional imaging. Methods: Computed tomography (CT) angiography images in 50 patients with PM or ICD implants were analyzed. Assessments at the level of the 4 th, 5 th and 6 th ICS were performed to determine if the path to the IS over the cardiac notch was obstructed by the lung or unavailable. Other measurements included sternal thickness, depth of the IS and distance of the internal thoracic vessels (ITV) from the left sternal margin. Images were analyzed and measured by an independent radiologist. Results: Evaluated subjects were 48% male aged with PM (78%) or ICD devices. Medical history included HTN (68%), AF (46%), HF (38%), CAD (38%) and Lung Disease (22%). At least one clear path to the IS through ICS 4, 5 or 6 existed in 48 (96%) subjects. Two PM patients with COPD had interposed lung tissue blocking access to the IS through ICS 4, 5 and 6. Conclusion: The IS was accessible in the vast majority of patients with PM or ICD devices in situ. This evaluation provides further support for the development of a novel completely extracardiac lead, delivered through an ICS over the cardiac notch of the left lung, to deliver pacing or defibrillation therapy without invading the heart or vasculature. B-PO AN EXTRACARDIAC PACING/ICD LEAD ALTERNATIVE FOR PATIENTS WITH CONGENITAL HEART DISEASE Anne-Floor B.E. Quast, MD, Jim T. Vehmeijer, MD, Martin C. Burke, DO, Reinoud Knops, MD, PhD, CCDS, Joris R. de Groot, MD, PhD, Alan Marcovecchio, Rick Sanghera and Richard Wasley, MD. Academic Medical Centre, Amsterdam, Netherlands, Academic Medical Center, Amsterdam, Netherlands, CorVita Science Foundation, Chicago, IL, Cameron Health, San Clemente, CA, AtaCor Medical, San Clemente, CA Background: Congenital Heart Disease (CHD) can make the management of cardiac arrhythmias particularly complex. Cardiac abnormalities and surgical histories can result in restricted vascular or ventricular access, inhibiting the placement of transvenous leads. Additionally, these patients are more prone to lead-related issues due to pacemaker/icd implantation at a younger age. Delivery and pacing with a completely extracardiac lead, inserted into the anterior mediastinum through an Intercostal Space (ICS) over the cardiac notch of the left lung, has been previously evaluated. This novel method may provide an attractive pacing/icd lead solution for patients with CHD as neither venous access nor contact with the heart tissue is required. Objective: A series of Computed Tomography (CT) chest angiography images, from CHD patients, was analyzed to determine the number of patients with a path to the anterior mediastinum through ICS 4, 5 or 6 that is unobstructed by lung tissue. Methods: CT images from 35 CHD patients were analyzed. Assessments at the level of the 4 th, 5 th and 6 th ICS were performed to determine if the path to the anterior mediastinum through an ICS was obstructed by the lung. Additional anatomy relevant to lead placement was also characterized. Results: Evaluated subjects were 49% male, aged (mean 41) years at the time of CT imaging. CHD included left sided heart lesions (40%), transposition of great arteries (20%), Tetralogy of Fallot (17%), Fontan circulation (3%) and other unique constellations of congenital malformations. 97% of patients had a history of at least one cardiac surgery, with a mean age of 11.1 years at the time of first surgery. At least one clear path to the IS through ICS 4, 5 or 6 existed in 100% of subjects. Conclusion: A clear path to the anterior mediastinum for placement of an extracardiac lead was observed in all patients, despite a broad range of congenital heart defects. Results from this evaluation suggest that an extracardiac pacing/icd lead delivered to the anterior mediastinum through an ICS, over the cardiac notch of the left lung, may provide an attractive alternative over existing approaches for patients with CHD. B-PO INFLUENCE OF RIGHT VENTRICULAR LEAD POSITION ON INTERVENTRICULAR ELECTRICAL DELAY IN PATIENTS RECEIVING CARDIAC RESYNCHRONIZATION THERAPY Dejan Mijic, MD, Fabian Schiedat, MD, Zana Karosiene, MD, Harilaos Bogossian, MD, Markus Zarse, MD, Bernd Lemke, MD, PhD and Axel Kloppe, MD. Gemeinschaftspraxis, Wuppertal, Germany, Cardiology Bergmannsheil Bochum, Bochum, Germany, Klinikum, Luedenscheid, Germany, Klinikum Luedenscheid, Witten/Herdecke University, Luedenscheid, Germany, Univ Hospital Aachen, Luedenscheid, Germany, Maerkische Kliniken, Luedenscheid, Germany, Universitätsklinikum Bergmannsheil, Bochum, Germany Background: Cardiac resynchronization therapy (CRT) is an effective therapy in patients (pts) with systolic heart failure and left ventricular dyssynchrony. The Interventricular electrical delay (IVED) has been shown to be an independent predictor of mortality. Objective: The aim of this study was to evaluate the influence of the right ventricular (RV) lead position on the IVED. Methods: 41 pts were enrolled undergoing implantation of a CRT system ( years, 61% male, 56% CHD, 90% sinus rhythm, QRS ms, LVEF %) using a LV quadripolar lead (SJM Quartet 66%, Medtronic %, Medtronic %, Biotronik Sentus Pro 5%). All pts received a RV single coil active fixation lead. After implantation of the RV and LV lead, the right atrial (RA) lead was temporarily placed in the RV apex before targeting it in the right atrium. Therefore the sensed (RVs) and paced (RVp) conduction times between RV (apical vs. non-apical position) and LV (LV1/2 and LV3/4) were measured. Results: In 21 pts (51%) the RV lead was implanted in a high septal position, whereas 20 pts (49%) received the RV lead in a mid-septal position. The LV lead was implanted in 25 pts (61%), 15 pts (37%) and 1 pt (2%) in the lateral, posterolateral and anterolateral region respectively. In the apical RV position the mean RVs-LV1/2 interval was ms compared to ms (p <0.001) in a non-apical RV position. The mean RVs-LV3/4 interval was measured by ms at apical RV position compared to ms (p <0.001) at non-apical RV position. In the apical RV position the mean RVp-LV1/2 interval was ms compared to ms (p = 0.64) in a nonapical RV position. The mean apical RVp-LV3/4 interval was measured by ms compared to ms (p = 0.44) at non-apical RV position. In comparison with high septal lead position pts with mid-septal lead position showed no statistical difference concerning RVs and RVp conduction times.

20 Poster Session V S507 Conclusion: Non-apical RV lead position during CRT results in a significant longer sensed IVED compared to an apical RV lead position. This effect does not occur under stimulation. The latest sensed and paced LV activation time occurs at the proximal poles of the LV lead (LV3/4), which indicates the optimal stimulation site for CRT. B-PO USE OF 3D PRINTED MODELS TO OBTAIN PHYSICIAN FEEDBACK ON DELIVERY TOOL DESIGN FOR A NOVEL EXTRAVASCULAR ICD IMPLANT PROCEDURE Varun Bhatia, PhD, Bridget Portway, BS, Maggie Pistella, Jerry L. Metcalf, Ian G. Crozier, MBCHB, MD, FHRS and David Shaw, MD. Medtronic, Mounds View, MN, Medtronic, Saint Paul, MN, Canterbury Health Limited, Christchurch, New Zealand, Canterbury Health Limited, Christchurch, New Zealand Background: The Extravascular ICD (EV ICD) is a novel system designed to place an ICD lead outside the vasculature in the anterior mediastinal space. The design of the delivery tool used to place the lead in this space is crucial for a safe and successful implant. Objective: To evaluate tunneling tool designs and recommended implant procedures used to deliver the EV ICD lead in the mediastinal space, using 3D printed models representing varying anatomies, which cannot be simulated using animal or human cadaver testing. Methods: Different body habitus were represented using 5 3D printed torsos, starting from clinical CT scans (Fig 1). Different materials represented different organs in the torso to simulate realistic boundary conditions the tool may experience in-vivo. Four tool designs were assessed by 16 physicians, on specific criteria: control of insertion, pivot, tunneling, visual confirmation of tool location, and ease of use. The data were analyzed using Pugh analytical techniques, to determine design attributes which most effectively and consistently performed across the different anatomies. Results: Tool designs with better tactile feedback were rated higher than the tools that hindered the same. The result of the Pugh analyses was used to propose an implant tool design with high confidence to work in expected patient anatomies. Conclusion: The 3D printed models acted as a powerful alternative to cadavers, to obtain feedback on the tunneling tool design and implant procedure challenges, based on different body habitus. The feedback received was used to optimize the design of the EV ICD tunneling tool and physician training strategy. B-PO DOES PRIOR STERNOTOMY OFFER PROTECTION IN TRANSVENOUS LASER LEAD EXTRACTION? Darren C. Tsang, BS, Ryan Azarrafiy, BA and Roger G. Carrillo, MBA, MD, FHRS, CCDS. University of Miami Miller School of Medicine, Miami, FL, Miami Shores, FL Background: A history of open heart surgery has been a point of controversy for transvenous lead extraction (TLE). While a European study suggests prior sternotomy is protective against clinical failure, other centers report differently. Objective: Thus, this study reports the clinical outcomes of TLE in patients with prior sternotomy at our institution. Methods: Data for all patients undergoing laser lead extraction at a single tertiary cardiovascular referral center was prospectively gathered from January 2003 to July 2017, using the institution s ongoing registry. Two cohorts were generated based on patients prior history of sternotomy. JMP Pro V13 (SAS, Cary, NC) was used to statistically compare the following variables: age, sex, body mass index (BMI), defibrillator leads, history of diabetes mellitus (DM), indication for extraction, lead dwell time, clinical success as defined by the 2009 HRS Consensus, and survival at discharge. Results: Of 1478 patients reviewed, 455 had a prior sternotomy. Patients with a prior sternotomy were significantly more likely to be older, male, and present with defibrillator leads and a history of DM. No statistical differences were noted in lead dwell time, indication for extraction, survival at discharge, and clinical success rate between the two cohorts. Conclusion: Patients with prior sternotomy undergoing laser lead extraction presented with significantly more comorbidities and defibrillator leads. However, no significant association between clinical success and prior sternotomy was immediately observed at our institution. Variables All Patients (n=1478) Table 1. Results Sternotomy (n=455) No Prior Sternotomy (n=1023 p-value Age 67.2 (± 15.1) 69.6 (± 12.3) 66.0 (± 16.1) <0.001 Sex, Female 393 (26.6) 72 (15.8) 321 (31.4) <0.001 BMI 27.9 (± 6.7) 27.6 (± 5.8) 28.1 (± DM 606 (41.0) 204 (44.8) 402 (39.3) Defibrillator leads 956 (64.7) 319 (70) 637 (62.3) Indication for extraction, 818 (55.7) 261 (57.4) 557 (54.9) 0.39 Infectious Lead dwell time, Years 5.9 (± 5.4) 6.0 (± 5.2) 5.9 (± 5.5) 0.61 Clinical success 1405 (95.1) 430 (94.5) 975 (95.3) 0.51 Discharged alive 1411 (95.5) 428 (94.1) 983 (96.1) 0.08 B-PO TRANSVENOUS LEAD EXTRACTION IN CRT PATIENTS IS NOT ASSOCIATED WITH INCREASED IN-HOSPITAL MORTALITY Justin Gould, MBBS, Bradley Porter, MBBS, Simon Claridge, Esq., LLB MBBS, Magda Klis, Benjamin J. Sieniewicz, MBChB, Baldeep Singh Sidhu, Steven Williams, MBBS, Mark O Neill, Jaswinder Gill, MD FRCP and Christopher A. Rinaldi, MD, FHRS. King s College London, London, United Kingdom, Guy s and St Thomas Trust, London, United Kingdom, King`s College London, London, United Kingdom, London, United Kingdom, Guy s & St Thomas Hospital, London, United Kingdom, Guys and St. Thomas Hospital, London, United Kingdom, St. Thomas Hospital, Cardiac Dept, London, United Kingdom Background: Transvenous lead extraction (TLE) may be necessary due to system infection/erosion or lead malfunction. CRT patients undergoing TLE may be at greater risk due to increased comorbidities. Objective: To determine if TLE of CRT is associated with higher in-hospital mortality than TLE of non-crt devices. Methods: All TLEs between were prospectively collected. 928 TLEs occurred during this period (227 CRT vs 701 non-crt).

21 S508 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Results: CRT patients were older (68 ± 11 vs 64 ± 16 years, p=0.03); more likely male (85% vs 70%, p<0.001); had lower LVEF at extraction (34% ± 13% vs 48% ± 13%, p<0.001); had higher prevalence of renal impairment (34% vs 13%, p<0.001); more likely to have > 2 comorbidities (eg diabetes) (84% vs 41%, p<0.001). Lead dwell time was lower in the CRT group (67 ± 67 vs 90.0 ± 85 months, p<0.001). Infective indication rate was similar in CRT and non-crt groups (51%, n=115 vs 56%, n=390, p=0.152). There was no significant difference in the 30-day mortality rate between the CRT (3.1%, n=7) and non-crt patients (2.4%, n=17) (p=0.64). The majority of deaths in both groups were due to severe sepsis. Univariate analysis showed age, renal impairment and infective endocarditis (IE) were associated with increased risk of 30-day mortality (Figure 1A). These remained independent predictors of 30-day mortality in a multivariate analysis (Figure 1B). Device type (CRT vs non-crt) did not predict mortality at univariate or multivariate analysis. Conclusion: TLE in CRT patients was not associated with increased mortality when compared to non-crt patients. Age, renal impairment and IE were independent predictors of 30-day mortality. Infection was the main cause of in-hospital mortality. switch, and (1) anomalous coronary artery. Summary statistics are reported in Table 1. Of note, 17 cases were extracted using percutaneous methods and 2 cases necessitated the use of alternative, minimally invasive approaches. Conclusion: Despite challenges with anatomic abnormalities, successful laser lead extraction can be safely accomplished in the congenital heart disease population. Table 1. Summary Statistics Variables Congenital Heart Disease Patients (n=19) Age 37.9 (± 11.1) Sex, Female 8 (42%) Device extracted 10 Defibrillators (53%), 6 Pacemakers (31%), 3 Cardiac Resynchronization Therapy-Defibrillators (16%) Lead dwell time, Years 9.0 (± 9.6) Indication for extraction, Infectious 3 (16%) Major or Minor complication 0 (0%) Procedural success 19 (100%) Length of stay, Days 4.2 (± 2.3) Discharged alive 19 (100%) B-PO TRANSVENOUS MANAGEMENT OF LATE PERFORATION BY CARDIAC IMPLANTABLE ELECTRONIC DEVICE LEADS Peter M. Jessel, MD, FHRS, Babak Nazer, MD, Thomas A. Dewland, MD and Charles A. Henrikson, MD, FHRS. VA Portland Health Care System/Oregon Health & Science University, Portland, OR, Oregon Health and Sciences University, Portland, OR, Oregon Health & Science University, Portland, OR, Knight Cardiovascular Institute, Portland, OR B-PO OUTCOMES OF LASER LEAD EXTRACTION IN PATIENTS WITH STRUCTURAL CONGENITAL HEART DISEASE: A SINGLE-CENTER EXPERIENCE Darren Chen Tsang, BS, Ryan Azarrafiy, BA and Roger G. Carrillo, MBA, MD, FHRS, CCDS. University of Miami Miller School of Medicine, Miami, FL, Miami Shores, FL Background: Patients with congenital heart disease are at increased risk for intracardic device malfunction or infection requiring lead extraction. However, given the anatomical challenges in this population, the risk of extraction remains understudied. Objective: We report the outcomes of laser lead extraction in patients with structural congenital heart disease at our institution. Methods: Data for all patients undergoing lead extraction at a single tertiary cardiovascular referral center was prospectively gathered from January 2003 to July 2017 using the institution s ongoing registry. Patients with congenital heart defects were identified. JMP Pro V13 (SAS, Cary, NC) was used to generate summary statistics for the following variables: age, sex, device extracted, lead dwell time, indication for extraction, approach, major and minor complications as defined by the 2009 HRS consensus, procedural success, length of stay, and survival at discharge. Results: Nineteen patients with congenital heart defects were identified: (7) tetralogy of Fallot, (4) D-transposition of the great arteries with atrial switch correction, (3) atrial/ventricular septal defect, (2) aortic stenosis requiring graft, (1) double outlet right ventricle, (1) D-transposition of the great arteries with arterial Background: : Late symptomatic cardiac implantable electronic device lead perforation is a rare, but likely underreported phenomenon. Uncertainty exists regarding percutaneous or open surgical management for late lead perforation. Objective: To review our single center experience of late lead perforation referrals. Methods: Patients referred for late (> 30 days) lead perforations from 2011 to 2017 were included. Lead management procedures were performed in a hybrid OR with transesophageal imaging and immediate surgical back up. All patients were initially managed with percutaneous extraction, with surgical extraction for tamponade or vascular injury. Results: Nine patients were identified with late lead perforation which presented from days after index procedure. All but one patient presented with pericardial chest pain or muscle stimulation. Five patients had an associated effusion (4 pericardial, 1 pleural) on presentation and 4 of 5 had the effusion drained percutaneously prior to lead removal. In 2 patients, the lead extended beyond the parietal pericardium. In 7 patients, the offending leads were removed with traction. One young asymptomatic patient had a perforated lead (fractured Riata) for 6 years that required open sternotomy. Complications included one episode of transient sepsis and one pocket infection. Late lead perforations accounted for 3% of our lead management cases in the hybrid operating room. Conclusion: Our single center experience suggests late lead perforation can be initially managed with a cautious transvenous approach, but intraprocedural ultrasound for pericardial monitoring and a rescue plan with immediate surgical back up is mandatory.

22 Poster Session V S509 B-PO CHRONIC TISSUE ENCAPSULATION PROFILE OF EXTRAVASCULAR VERSUS TRANSVENOUS LEADS Amy Thompson, MS, MBA, Melissa G.T. Christie, MS, Mark T. Marshall, BSME, MASC, Jaime Paulin and Nicole Kirchhof, DVM. Medtronic, Minneapolis, MN, Medtronic, Inc., Mounds View, MN, Medtronic Inc, MoundsView, MN Background: Extravascular (EV) ICDs may prove to be a valuable alternative to transvenous (TV) ICDs. A novel EV ICD system is proposed placing a customized lead in the space between the sternum and pericardium to preserve standard energy defibrillation and ATP capability. Tissue encapsulation of a lead implanted in this space has not been well characterized, and encapsulation has bearing on both lead stability and extractability. Objective: Evaluate, with histopathology, the chronic encapsulation profile of EV leads. Methods: Two chronic studies were conducted. A 12-week study in five swine compared a novel EV lead to a marketreleased TV ICD lead implanted in the RV apex. The EV and TV leads were of similar construction, diameter, and outermost insulation material. A second study was conducted in five ovine, with two of the novel EV leads implanted in each animal for one year. Results: Comparison of EV and TV leads from the 12-week study revealed tissue capsules of similar thickness, maturity and inflammatory response. EV leads had fibrous capsules of advanced but not yet complete maturity; TV capsules were composed of paucicellular fibrous tissue and frequently had thrombus adhered. EV capsule thicknesses ranged from 20-1,740 μm (average: 518 μm); TV capsules ranged from 50-1,970 μm (average: 476 μm). Results of the one-year study showed mature tissue capsules with low cellularity and inflammation an expected finding for the longer implant duration. Conclusion: At 12 weeks, histomorphological characteristics of the perilead encapsulation were similar between EV and TV leads, even though the distal portion of the EV lead was implanted within a tissue environment and the TV lead within a hematogenous environment. Importantly, the tissue capsules were of similar thickness and comparable in their maturity and inflammatory response. In the one-year specimens, no further remodeling or additional biologic response was observed. B-PO COMPARISON OF SURVIVAL RATE OF IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR LEADS AMONG MANUFACTURE - DURATA VS SPRINT QUATTRO VS LINOX - Yusuke Kondo, MD, PhD, Masahiro Nakano, Keitaro Senoo, Miyo Nakano, Tomohiko Hayashi, Ryo Ito and Yoshio Kobayashi. Chiba University Graduate School of Medicine, Chiba, Japan, Department of Cardiovascular Medicine C, Chiba, Japan Background: Implantable cardioverter-defibrillators (ICDs) prevent sudden arrhythmic death (SAD) and improve clinical outcomes in patients for either primary and secondary prevention of SAD. However, ICD lead dysfunction is a major concern in ICD recipients, whether due to manufacturing defects or random failure. Objective: The purpose of this study was to assess the survival rate of St. Jude Medical Durata, Medtronic Sprint Quattro and Biotronik Linox ICD leads. Methods: We retrospectively reviewed consecutive patients who had undergone implantation of Durata, Linox and Sprint Quattro leads between March 2005 and September Variables associated with lead failure were assessed by the Kaplan-Meier method and Cox survival modeling. Results: A total of 305 ICD leads were analyzed (Durata (n=112), Linox (n=66) and Sprint Quattro (n=127) leads). Figure shows the survival rate of these leads, respectively. The failure rates of Durata, Linox and Sprint Quattro were 0.20%/year, 0.62%/year and 2.2%/year, respectively. Conclusion: The survival rate of St. Jude Medical Durata leads was significantly high, compared to Biotronik Linox and Medtronic Sprint Quattro leads, in this population. The survival rate of Medtonic Sprint Quattro leads was unacceptably low. B-PO P-WAVE VISIBILITY FROM EXTRAVASCULAR FAR-FIELD AND NEAR-FIELD ELECTROGRAMS: SUB-ANALYSIS FROM THE SUBSTERNAL PACING ACUTE CLINICAL EVALUATION ( S P A C E ) TRIAL Peter Leong-Sit, MD, FHRS, Darius Sholevar, M.D., Stanley Tung, MD, FHRS, Vikas P. Kuriachan, MD, FHRS, Henri Roukoz, MD, FHRS, Gregory Engel, MD, Steven P. Kutalek, MD, FHRS, CCDS, Devender N. Akula, MD, FHRS, Jian Cao, PHD, Marina Ostanniy, MS, Michael Bennett, MS and Franck Molin, MD. London Health Sciences Centre, London, ON, Canada, Lourdes Cardiology Services, Cherry Hill, NJ, Royal Columbia Hospital, Vancouver, BC, Canada, University of Calgary, Calgary, AB, Canada, University of Minnesota, Cardiology, Electrophysiology, Edina, MN, Sequoia Hospital, Redwood City, CA, Drexel Univ College of Medicine - Hahnemann Univ Hospital, Philadelphia, PA, Moorestown, NJ, Medtronic, Inc., Minneapolis, MN, Medtronic Inc, Mounds View, MN, Quebec Heart Institute, Québec, QC, Canada Background: P-wave visibility in ICDs is important for rhythm diagnosis. However, it is unclear if P-wave amplitudes will be adequate in a novel extra-vascular (EV) ICD system with a lead

23 S510 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 in the anterior mediastinum. Objective: To characterize P-wave amplitudes in both far-field and near-field electrograms (EGMs) with electrodes positioned in the mediastinal tissue from the SPACE trial. Methods: In subjects undergoing sternotomy or subcutaneous ICD implant, a 7F decapolar catheter (Marinr, Medtronic) was temporarily placed under the sternum with the mid-electrode pair centered over the right ventricle. A skin patch electrode was placed on the left thorax. Results: We analyzed all available EGM recordings in 14 subjects (10 males; mean age 63.1+/-11.5 yr). P-waves from a wide bipole (electrodes (e)1-10) or far-field EGM (e1 or e6 to patch) were larger (P<0.05) than a closely spaced bipole (e5-e6). P-waves were generally larger for electrodes closer to atrium (Fig.1). Conclusion: This analysis suggests that far-field and widelyspaced near-field EV electrograms may be of adequate amplitude to visualize P-waves from the mediastinal space in an extra-vascular ICD. Results: A cohort (n=312) with mean age of years and 57% males was reviewed. The mean CHADS2VaSc score was 1 (range 1-3). 146(46.85) patients had a change in management with a cardiac intervention performed in 62(42.5%) patients leading to a number needed to treat(nnt) of Figure 1a describes NNT in the overall cohort and subgroups of symptoms. Figure 1b outlines the duration of time patients underwent ILR monitoring prior to the establishment of a diagnosis. Factors contributing significantly to the diagnosis using an ILR in a multivariate analysis include male gender (odds ratio[or] 2.14; confidence intervals [CI] ; p value 0.002) and syncope (OR 2.06; CI ); p value 0.01) Conclusion: ILR monitoring provides information critical to the management of patients with single or multiple symptoms of a possible cardiac etiology B-PO DIAGNOSTIC AND THERAPEUTIC VALUE OF IMPLANTABLE LOOP RECORDER: A TERTIARY CARE CENTER EXPERIENCE Deepak Padmanabhan, Krishna Kancharla, Majd El-Harasis, Ameesh Isath, Nayani Makkar, MBBS, Peter A. Noseworthy, MD, Paul A. Friedman, FHRS, Yong-Mei Cha, MD, FHRS and Suraj Kapa, MD, FHRS. Mayo Clinic, Rochester, MN, University of Pittsburgh, Sewickley, PA, Mayo Clinic, Rochester, New Delhi, India Background: High health care costs are associated with implantation and follow-up of loop recorders(ilrs). However, the clinical milieu of their use and the symptom specific diagnostic yield is uncertain Objective: We aimed to derive number needed to treat(nnt) as well as the duration of time needed prior to the establishment of a diagnosis after ILR implantation Methods: We reviewed the use of ILR implanted at Mayo Clinic, Rochester, Minnesota between April 2010-May We classified the outcomes of this monitoring based on their diagnostic and therapeutic value in patient management and calculated the time these patients needed monitoring prior to diagnosis. Univariate and multivariate analysis using logistic regression model was used to identify pre-implantation parameters contributing to monitoring success. B-PO OUTCOMES OF PERMANENT PACEMAKER IMPLANTATION AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT: A PROSPECTIVE STUDY Ying Tian, MD, PhD, Paul A. Friedman, FHRS, Christopher J. McLeod, MD, Gurpreet S. Sandhu, MD, PhD, Kevin L. Greason, MD, Rajiv Gulati, MD, PhD, Vuyisile T. Nkomo, MD, MPH, Lynn E. Polk, RN, Carrie Sanvick, RN, Deepak Padmanabhan and Yong-Mei Cha, MD, FHRS. Mayo Clinic, Rochester, MN Background: Cardiac conduction disturbances requiring permanent pacemaker (PPM) implantation is a common complication of transcatheter aortic valve replacement (TAVR). Objective: To investigate the incidence and predictors of improving intrinsic conduction in patients who received PPM implantation after TAVR. Methods: From June 2016 to August 2017, 435 patients underwent TAVR at the Mayo Clinic, Rochester, MN. Of these, 52 (12.0%, age 81 ± 8 years) patients underwent PPM

24 Poster Session V S511 implantation before hospital discharge. These patients returned at 30 days for follow-up at the valve and device clinic following a pre-defined prospective TAVR practice protocol. Results: One patient died within 30 days of procedure and 3 patients did not return for follow-up. Among 48 patients who had follow-up, 22 (45.8%) receive PPM for high-degree (II or III degree) atrioventricular block (AVB) and 26 (54.2%) for newonset left bundle branch block (LBBB). Most of study patients (44/48, 91.7%) received Edwards SapienS3 valves while the other 4 patients received Medtronic EvolutR Core Valve. At 30-day follow-up, 18 (37.5%) patients had improvement in conduction: new LBBB resolved in 6/26 (23%) patients and high-degree AVB resolved in 12/22 (54.5%) patients. Prior percutaneous coronary intervention or baseline normal cardiac conduction were associated with improvement in conduction (OR 6.6, 95% CI , P=0.009 and OR 5.1, 95% CI , P=0.025 respectively). Among 26 patients with new LBBB, 16 (61.5%) were unchanged and 4 (15.3%) progressed to AVB requiring pacing. Of 10 patients who developed highdegree AVB after TAVR and remained to be pacing dependent, 9 (90%) had preexisting RBBB. Multivariate analysis showed that RBBB prior to TAVR was an independent factor for PPM dependency (OR 12.4, 95% CI , P=0.002). Conclusion: Improvement in AVN or infra-his conduction may occur in one-thirds of patients with new high-degree AVB or LBBB after TAVR procedure and therefore may need long term monitoring. Preexisting RBBB before TAVR often demands PPM for long-term pacing support. B-PO ASSESSMENT OF THE IMPACT OF RIGHT VENTRICULAR FUNCTION ON CLINICAL OUTCOMES AFTER CARDIAC RESYNCHRONIZATION THERAPY WITH MAGNETIC RESONANCE IMAGING AND ECHOCARDIOGRAPHY Eliany Mejia Lopez, MD, Michael Millar, MD, Benjamin Ruth, MD, Jamie L. Kennedy, MD, Daniel A. Auger, PhD, Frederick H. Epstein, PhD, Sula Mazimba, MD and Kenneth C. Bilchick, MD, MS, FHRS. University of Virginia, Charlottesville, VA, University of VA Health System, Cardiology, Charlottesville, VA Background: Baseline right ventricular (RV) function is an important predictor of clinical outcomes in heart failure (HF). Objective: To identify the independent impact of RV function on clinical outcomes after cardiac resynchronization therapy (CRT) based on analyses using magnetic resonance imaging (MRI) and echocardiography. Methods: Patients with HF had MRI and echocardiography prior to CRT to assess RV function (RV fractional area change [RVFAC]) and LV dyssynchrony (circumferential uniformity ratio estimate with singular value decomposition [CURE-SVD]), then had follow-up for the clinical endpoint of death, LV assist device, or orthotopic heart transplant [D-LVAD-OHT]) and the reduction in the LV end-systolic volume (LVESV) by echocardiography post-crt. Results: Among 70 patients (age 63.3 ± 15 years, 34% female), RVFAC improved post-crt in 41 (58.6%), while 40 (57.1%) had an LVESV reduction of at least 15%. A lower RVFAC pre- CRT was independently associated with less improvement in the LVESV post-crt in a multivariable linear regression model adjusted for CURE-SVD (standardized coefficient for RVFAC, P < 0.01). During a median follow-up of 3.4 years, 17 patients (24.3%) had D-LVAD-OHT, and a lower pre-crt RVFAC was independently associated with this D-LVAD-OHT endpoint (adjusted HR 0.53 per 10% increase in RVFAC [P = 0.006] in a Cox proportional hazards model; log-rank P < 0.01 for RVFAC > 35% v. RVFAC 35% [Figure]). Conclusion: Impaired RV function is a powerful predictor of adverse clinical events and unfavorable LV remodeling after CRT, even after adjustment for a validated MRI LV dyssynchrony parameter. B-PO HOSPITAL IN-PATIENT REMOTE INTERROGATION OF CARDIAC DEVICES IS EFFECTIVE AND SIGNIFICANTLY DECREASES THE NEED FOR BED-SIDE SPECIALIST INTERACTION E. Martin Kloosterman, MD, FHRS, Jonathan Z. Rosman, MD, FHRS and Murray Rosenbaum, MD, FHRS. Boca Raton Regional Hospital, Boca Raton, FL, Cardia Arrhythmia Service, Boca Raton, FL Background: The use of hospital remote interrogation of cardiac devices (CIED) has had mixed adoption and utilization. Understanding the advantages of its usage streamlines patient care and would have time and economic savings. Objective: To evaluate that the systematic use of a protocol for hospital remote interrogation (RI) of cardiac devices decreases the need of an in-person bed-side specialist (physician or technician) interaction. Methods: A protocol for the use of hospital remote interrogation of CIED was created with access to this system in all hospital locations. A total of 100 consecutive orders for CIED checks were evaluated in patients using one specific company system (Medtronic). Results: Of the 100 CIED check orders, remote interrogation was performed in 97. In 3 CIED evaluations RI was not used but bed-side in-person was required (1: had a known need for CIED reprogramming, and 2: had nursing impediment issues). The RI transmission time average 15 minutes. The response time to RI varied according to timed orders and patient needs. Hospital indication/distribution was ER:19; Post-OP: 31; general: 50. The RI was conducted in 55% of the time between 7PM and 7 AM. The majority of CIED RI, 86 (89%) required no further CIED interaction. Eleven (11%) were subsequently in person interrogated, of those only 5 (5%) needed CIED reprograming and in 6 (6%) post op thresholds were performed as not automatically provided in the RI initial report. Conclusion: The use of in-patient hospital remote interrogation of CIED can be applied to almost all clinical conditions reducing 85% the need of in person interrogation by a specialist with time and economic savings repercussions. Further if next day thresholds were to be found non-essential then only 9% of the time an in person interaction would be needed for a CIED evaluation.

25 S512 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO RACIAL DIFFERENCES IN THE INCIDENCE OF ATRIAL FIBRILLATION IN PATIENTS WITH CRYPTOGENIC STROKE - A TWO-CENTER STUDY Mark Heckle, MD, Erin Shahan, BSN, RN FA, Sarah E. Longserre, BSN, RN FA, Hector C. Hernandez, MD, Neil Barry, DO, Rakesh Gopinathannair, MA, MD, FHRS and Rajesh Kabra, MD, FHRS. University of Tennessee Health Science Center, Memphis, TN, University of Louisville School of Medicine, Cardiology/EP, Louisville, KY, University of Louisville School of Medicine, Cardiology, Louisville, KY, University of Tennessee Health Sciences Center, Memphis, TN Background: African American (AA) patients have a higher incidence of stroke but lower prevalence of AF than whites. Studies involving long term monitoring for atrial fibrillation (AF) after cryptogenic stroke are limited by the underrepresentation of the AA population. Objective: We sought to assess racial differences in the diagnosis of AF by implantable loop recorder (ILR) in patients with cryptogenic stroke. Methods: In this two-center retrospective chart review study at Methodist University Hospital, University of Tennessee Health Science Center, Memphis TN and University of Louisville Hospital, Louisville KY, we included patients with cryptogenic stroke who received an implantable loop recorder (Medtronic LINQ) from September 2014 to November 2017 to assess for AF. Race and other demographic characteristics were obtained from the electronic medical records. Interrogation reports from the ILR s were obtained by remote monitoring as well as clinic visits. Fisher exact and student t test were used to compare demographic data as well as the incidence of atrial fibrillation in these patients. Results: A total of 133 patients (35 AA and 98 whites) with cryptogenic stroke underwent ILR implantation. AA patients were younger than whites (59.1 versus 66.7 years; p < 0.01) and had a significantly higher prevalence of hypertension and coronary artery disease than whites. Over a mean follow up period of 310 days, 36 patients (27.1%) were diagnosed with AF on ILR monitoring. The median time to the incidence of AF was 42 days. The incidence of AF was significantly higher in the white population (24.1%) as compared to the AA population (7.7%) (p<0.05). Conclusion: In patients with cryptogenic stroke, white patients had a significantly higher incidence of AF than AA patients on long term monitoring with implantable loop recorders. This suggests that factors other than AF may play a more important role in stroke causation in AA patients, compared to whites. B-PO CARDIAC IMPLANTABLE ELECTRONIC DEVICES MONITORING AND RISK FOR STROKE EVENTS IN OLDER PATIENTS Shinya Shiohira, MD, Shingo Maeda, MD, Shun Nakagama, Aiko Fujimaki, Kiko Lee, Masahiro Sekigawa, Atsuhiko Yagishita, MD, Yoshihide Takahashi, MD, Mihoko Kawabata, Masahiko Goya and Kenzo Hirao, MD. Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo, Japan, Tokyo Medical and Dental University, Tokyo, Japan, Japan, Tokyo, Japan, Heart Rhythm Center, Tokyo Medical and Dental University, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: According to the recent guidelines, anticoagulation therapy may be recommended to the patients with cardiac implantable electronic devices (CIEDs) who had previously no atrial fibrillation (AF) but have the episodes of AF/AT (atrial tachycardia) during CIEDs monitoring. In addition, Stroke prevention Strategies based on Atrial Fibrillation information from implanted devices project suggested device-detected AF burden is associated with an increased risk of ischaemic stroke in a relatively unselected population of CIEDs patients. Objective: The relationship between the AF/AT burdens and stroke occurrence remains unclear in old patients. Methods: This study included 788 consecutive patients who visited to our pacemaker clinic, and of whom 584 were eligible for the age criteria (mean age: 78.6±7.3 years old, male: 329). We evaluated the duration of persistence of the AF/AT episodes and the stoke events in them. Results: Of 584 patients, the AT/AF episodes were detected in 55.3 % (323 patients; 78.8 y/o, male 181) during 2308 days follow-up, and new AF episodes were documented in those of 45%. We divided patients into 3 groups based on AT/AF duration; Group-1: AT/AF>60min (n=187), Group-2: AT/AF>5, 60min (n=58), Group-3: AT/AF 5min (n=78). Ten patients had cerebral infarction during follow-up, and cerebral infarction occurrence rate per year was higher in Group-1 and 2 compared to Group-3, 0.21%, 0.44% vs. 0.07%, respectively. Cerebral hemorrhage occurrence rate per year were similarly among 3 groups (Group-1 vs Group-2 vs Group-3=0.21% vs 0.15% vs 0.20%). Mean CHADS 2 score in patients with documented a new AF are 2.0±1.2, whereas those with a new cerebral infarction are 2.8±1.3. Conclusion: In older patients with CIEDs, the AF/AT episodes occurred about 55% during long term follow-up and the AF/ AT episodes lasting >5min is a possible risk factor for cerebral infarction. When a new AF episode is documented, anticoagulation should be considered if AT/AF episodes lasting >5min in old patients. B-PO RIGHT VENTRICULAR PACING HAS SHORT AND LONG- TERM DELETERIOUS EFFECTS ON VENTRICULAR PHYSIOLOGY Mohammad Paymard, MD, Eli Dunn, MBBS, Angeline Josiah, MBBS, Thomas Murchie, MBBS, Walter Abhayaratna and Rajeev K. Pathak, MBBS, PhD. The Canberra Hospital, Garran, Australia, Canberra Hospital, Canberra, Australia Background: Previous studies have suggested that in the longterm, right ventricular pacing may have some deleterious effects on cardiac structure and function. Objective: To evaluate short and long term adverse effects of RV pacing (apical and septal) on RV physiology. Methods: Consecutive pts who underwent device implantation (permanent pacemaker and implantable defibrillator) were screened. Chart review was performed to determine patient demographics, procedural details and outcomes. In patients who underwent transthoracic echocardiography (TTE) before and after (12 months and 5 years) were included in this study. The images were assessed for tricuspid regurgitation (TR), RV size and systolic function, Left atrial (LA) volume and Left ventricular diastolic function. Results: Between 2006 and 2016, out of 4108 patients with device implantation, 200 patients (71 % male, age 70 ± 14 years) had TTEs at baseline, 12 months and at 5 years. 170 pts. apical pacing and 30 pts had septal pacing. At baseline, 109 (54%) had no TR, 66 (33%) mild TR and 20 (10%) had moderate TR. In 160 (80%) RV size was normal with 40(20%) having mildly dilated RV. At 12 months, Mild TR was seen in 112 (56%), 39 (20%) moderate TR and 39 (9.5%) had severe TR. At 5 years, some worsening of TR in 90% with increase in RVSP and RV size was seen in 37% and 28% respectively (See table 1). Conclusion: Long-term RV pacing has significant deleterious

26 Poster Session V S513 effects on tricuspid valve function, RV size and RV systolic function. An alternative pacing site such as His pacing can be attempted to avoid long term RV pacing complications. SBP-drop for RIPVs (AUC=0.946, BCO=-22mmHg). Conclusion: Different in-procedural parameters might have to be used for different PVs to predict successful CB-PVI. B-PO B-PO COMPARISONS OF IN-PROCEDURAL PARAMETERS TO PREDICT SUCCESSFUL PULMONARY VEIN ISOLATION USING 2 ND- GENERATION CRYOBALLOON Takatsugu Kajiyama, MD, Hitoshi Hachiya, MD, Shinsuke Miyazaki, MD, PhD, Miyako Igarashi, Shigeki Kusa, MD, Kazuya Yamao, MD, Akinori Sugano, Yoshikazu Sato and Yoshito Iesaka, MD, PhD, FHRS. Cardiovascular Center, Tsuchiura Kyodo General Hospital, Tsuchiura, Japan, Tsuchiura Kyodo General Hospital, Tsuchiura, Ibaraki, Japan, Fukui University, Fukui-shi, Fukui, Japan, University of Tsukuba, Tsukuba, Japan, Tsuchiura Kyodo Hospital, Tsukuba, Japan, Tuchiura General Hospital, Tuchiura, Japan, Tsuchiura Kyodo Hospital, Tsuchiura Ibaraki, Japan Background: Although quick electrical disconnection of pulmonary vein (PV) seems to be important for pulmonary vein isolation (PVI), significant cases do not allow physicians to visualize PV potentials during PVI using cryoballoon catheter (CB-PVI). Objective: We compared in-procedural parameters which may reflect effectiveness of freezings in order to seek predictors for successful CB-PVI. Methods: We analyzed consecutive patients who underwent CB-PVI for paroxysmal atrial fibrillation as their first intervention. All CB-PVI was performed by a single 3-minute application technique. Freezings shorter than 3 minutes were excluded. Minimum in-balloon temperature (MinTemp), thawing time from the termination of freezing to in-balloon temperature to 15 C (ThawT), drop of systolic blood pressure after freezing (SBPdrop) were analyzed as predictors for successful PVI by first cryoapplication to each PV. Area under the receiver-operatorcurve (AUC) was individually compared for right superior PVs, right inferior PVs, left superior PVs, and left inferior PVs(RS/RI/ LS/LIPVs). Best cut-off value (BCO) to predict successful PVI was also calculated. Results: In the total of 63 patients (62.3 years, 40 males), 153 freezings were analyzed. They consisted of 113 successful freezings (25RSPVs, 28RIPVs, 30LSPVs, 30LIPVs) and 40 failed freezings (4RSPVs, 18RIPVs, 10LSPVs, 8LIPVs). As for in-procedural predictors, MinTemp (-52.1±5.4 vs -43.7±6.1 C, p<0.001), ThawT (40.6±11.8 vs -23.3±10.4sec, p<0.001), and SBP-drop (-44.1±19.1 vs -26.6±19.1mmHg, p<0.001) were significantly different between successful and failed freezings. The greatest AUC was obtained by MinTemp for LSPVs (AUC=0.873, BCO=-49 C) and RSPVs (AUC=0.910, BCO=- 44 C), by ThawT for LIPVs (AUC=0.812, BCO=28sec), and by INCREMENTAL BENEFIT OF BI-DIRECTIONAL BLOCK AS AN ENDPOINT OF PULMONARY VEIN ISOLATION: ONE- YEAR OUTCOME OF ATRIAL FIBRILLATION RECURRENCE Dian A. Munawar, MD, Rajiv Mahajan, MD, PhD, Thomas A. Agbaedeng, BSc, Kashif Khokhar, MBBS, Mehrdad Emami, MD, Anand Thiyagarajah, MBBS, Kadhim Kadhim, MBChB, Ricardo Sadashi Mishima, MD, Dominik K. Linz, MD, PhD, Dennis H. Lau, MBBS, PhD, FHRS, Roberts-Thompson C. Kurt, MBBS, PhD, Prashanthan Sanders, MBBS, PhD, FHRS and Glenn Young, MBBS. Unviversity of Adelaide, Royal Adelaide Hospital and Sahmri, Adelaide, Australia, Unviversity of Adelaide and Sahmri, Adelaide, Australia, University of Adelaide, Unley, SA, Australia, University of Adelaide, Beaumont, SA, Australia, Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia, Adelaide, SA, Australia, University of Adelaide, Adelaide, SA, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia, Cardiovascular Research Centre, Adelaide, Australia Background: Complete electrical isolation of pulmonary veins (PV) remains the cornerstone of atrial fibrillation (AF) ablation. However, various approaches to PV isolation (PVI) have shown variable efficacy in the outcome of AF recurrence. Objective: This study sought to evaluate the efficacy of bidirectional block as compared to entrance block only as an endpoint of PVI. Methods: We performed a retrospective analysis of patients undergoing de novo PVI from 2009 to 2014 for symptomatic AF with at least 1 year follow-up. Bi-directional block was confirmed by demonstration of: (a) entrance block (loss of all PV potentials), and (b) exit block (failure to capture the left atrium by pacing 10 bipolar pairs of the circumferential catheter placed at PV ostium). Recurrence of AF was evaluated on clinical visit at 3, 6, and 12 months after procedure, with exclusion of blanking period (3 months). Results: There were 137 consecutive patients included in this study (mean age years, female 37.5%). After 1 year period, recurrence of AF was lower in bi-directional than entrance only group (14 out of 77 patients (18.2%) vs 23 out of 60 patients (38.3%), respectively). The Kaplan Meier survival analysis showed a decrease in AF recurrence in the bi-directional block group (p value 0.005, log rank test) (see figure). The cox proportional hazards model also demonstrated a significant reduction in AF recurrence in bi-directional block group after adjusting for age, gender, and type of AF (HR 0.45; CI ; p value 0.03) Conclusion: This study suggest that bi-directional block confirmation after PVI procedure has a significant incremental benefit for prevention of 1-year AF recurrence.

27 S514 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 and left atrial diameter (LAd) (3/13 studies) were most frequently identified as being significant. Pooled results from studies reporting outcomes as hazards ratios (HR) did not identify a significant predictor, despite variables such as LAd (HR 1.03; 95% CI: ), LVEF (HR 1.00; 95% CI: ) and age (HR 1.00; 95% CI: ) having narrow confidence intervals associated with their estimates. Conclusion: Although a large proportion of individuals with isolated atrial flutter develop new AF after CTI ablation, the current evidence base is inconsistent and does not support risk-stratifying patients based on the presence of traditional AF risk factors. Larger prospective studies employing consistent arrhythmia detection strategies and rigorous statistical analyses will help clarify this issue. B-PO B-PO ATRIAL FIBRILLATION AFTER CAVOTRICUSPID ISTHMUS ABLATION FOR ISOLATED ATRIAL FLUTTER - CAN WE PREDICT HIGH RISK INDIVIDUALS? A SYSTEMATIC REVIEW AND META-ANALYSIS Anand Thiyagarajah, MBBS, Ricardo Sadashi Mishima, MD, Mehrdad Emami, MD, Dominik K. Linz, MD, PhD, Dian A. Munawar, MD, Kadhim Kadhim, MBChB, Melissa E. Middeldorp, Kashif B. Khokhar, MBBS, Rajiv Mahajan, MD, PhD, FHRS, Dennis H. Lau, MBBS, PhD, FHRS and Prashanthan Sanders, MBBS, PhD, FHRS. University of Adelaide, Royal Adelaide Hospital & SAHMRI, Adelaide, Australia, Adelaide, SA, Australia, University of Adelaide, Unley, SA, Australia, University of Adelaide, Adelaide, SA, Australia, Centre of Heart Rhythm Disorders, Forestville, Australia, Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia, Centre for Heart Rhythm Disorders, Norwood, Australia, Royal Adelaide Hospital, Centre of Rythm Disorders, Adelaide, Australia, Cardiology, Beaumont, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia Background: Amongst individuals with isolated atrial flutter, deciding who should continue anticoagulation following cavotricuspid isthmus (CTI) ablation presents a recurrent clinical dilemma. Given the efficacy of CTI ablation, continued anticoagulation may only be beneficial in the subset of patients who manifest new Atrial Fibrillation (AF). Objective: To determine whether established AF risk factors derived from population studies can predict progression to AF in patients with isolated atrial flutter. Methods: We used the Pubmed and Embase databases to perform a systematic review and meta-analysis of studies evaluating 12 pre-defined risk factors (AF inducibility, age, antiarrhythmic drug (AAD) use prior to ablation, coronary artery disease, heart failure, hypertension, left atrial size, left ventricular ejection fraction (LVEF), obesity, sex, structural and valvular heart disease) for the development of new AF after CTI ablation for isolated atrial flutter. Results: We identified 19 relevant studies that comprised 3 prospective and 16 retrospective cohort studies incorporating 3495 patients. Reported rates of new AF ranged from 13% over 19 mths to 82% over 39 mths. No variable was consistently identified as a significant independent predictor of new AF across individual studies. AF inducibility after CTI ablation (significant in 2/4 studies), AAD use prior to ablation (3/7 studies) ARRHYTHMOGENIC SUBSTRATE CHARACTERIZATION BY MYOCARDIAL PERFUSION IMAGING CAN HELP LOCALIZE FRACTIONATED VOLTAGE SIGNALS IN VENTRICULAR TACHYCARDIA PATIENTS Bernard Thibault, MD, FHRS, Louis-Philippe Richer, PhD, Luke C. McSpadden, PhD, Kyungmoo Ryu, PHD, Lena Rivard, MD,MSc, Katia M. Dyrda, MD, Marc Dubuc, MD, Laurent Macle, MD, FHRS, Blandine A. Mondesert, MD, Peter G. Guerra, MD, Paul Khairy, MD, PhD, Denis Roy, MD, FHRS, Rafik Tadros, MD PhD, Mario Talajic, MD, Jean Gregoire, MD and Francois Harel, MD, PhD. Montreal Heart Institute, Montreal, QC, Canada, Abbott, Saint-Laurent, QC, Canada, Abbott, Sylmar, CA, St. Jude Medical CRMD, Sylmar, CA, Universite De Montreal, Montreal, QC, Canada, Montréal Heart Institute, Montreal, QC, Canada, Academic Medical Center, Amsterdam, Netherlands Background: Substrate characterization using myocardial perfusion imaging (SPECT/CT) and electroanatomical mapping (EAM) data in combination may improve clinical outcome for patients with scar-related ventricular tachycardia (VT). Ischemic myocardium (IM) may help supporting the arrhythmogenic substrate identified by voltage mapping (VM). Objective: This study seeks to determine whether scar and/or IM revealed by SPECT/CT can guide the electrophysiologist in finding fractionated electrical signal with EAM. Methods: Ischemic VT subjects underwent SPECT/CT imaging (rest and stress) prior to left ventricular EAM with the EnSite Precision cardiac mapping system (Abbott). Data were exported post-ablation procedure for analysis. Scar and IM were localized on SPECT/CT geometry. Co-registration of the VM data allowed projection of highly fractionated signal and ablation lesion locations onto SPECT/CT geometries for integration with perfusion data (figure). Results: Five subjects (100% male, 64 ± 9 years old, LVEF 33 ± 11%) underwent VM and SPECT/CT integration. 12-lead ECGs located all VTs induced (n=15) in regions with scar/im. An average of 84.4 ± 11.4% of the highly fractionated signals were localized within or adjacent (<1cm) to scar areas with IM. VM guided ablations resulted in 70.1 ± 11.6% of the lesions within scar or IM. Conclusion: Preliminary results of this ongoing study show that ischemic myocardium was associated with highly fractionated electrograms and regions of interest for VT ablation. The physiologic and 3-D data combo provided by SPECT/CT may help physicians pre- and peri-procedure to identify and target areas of highest interest for ablation.

28 Poster Session V S515 B-PO B-PO IDENTIFICATION OF LATEST SITE(S) OF ACTIVATION WITHIN VOLTAGE BRIDGES, VOLTAGE TRANSITION ZONES, AND ADJACENT LOW VOLTAGE AREAS IN THE TRIANGLE OF KOCH TO GUIDE ABLATION FOR AVNRT Thomas K. Kurian, MD, L.Edwin Abney, MD, Amrit Gonugunta, Sterling Jones, MSc, Hong Mauricio, MD, FHRS and Kristopher M. Heinzman, MD. Seton Heart Institute, Austin, TX, Dell Medical School, Austin, TX, University of Texas at Austin, Austin, TX, St Jude Medical, Austin, TX, UT Southwestern, Dallas, TX Background: Voltage mapping of the triangle of KOCH has been performed to identify ideal ablation sites based on voltage characteristics including voltage bridges, voltage transition zones, and adjacent low voltage areas with 3D mapping systems. Targeting of latest site(s) of activation in sinus rhythm with Ablation in conjunction with voltage mapping characteristics has not been defined. Objective: Identify ideal ablation sites utilizing the latest site(s) of activation in sinus rhythm within the Triangle of Koch and characterize within the context of voltage mapping characteristics with 3D mapping systems for AVNRT. Methods: Voltage gradient mapping was performed undergoing AVNRT ablation with 3D mapping systems using St Jude Velocity/Precision and Bio-sense webster Carto Mapping Systems at 0.5 mv - 1.5mV. The latest activation site(s) were annotated in sinus rhythm using a 4 mm ablation catheter characterized in the context of voltage mapping and targeted with RFA. Results: Of the twenty-one patients evaluated, 100% ( 22/22) patients mapped were noted to have latest activation site(s) in SR to be within 3-5 mm circumference to voltage bridges, voltage transition zones and adjacent low voltage areas. Targeting the latest site of activation resulted in slow junctionals ( > 2 beats )in 95% of patients (21/22) tested. Conclusion: Identification and characterization of latest site(s) of activation with voltage and timing mapping of the Triangle of Koch can be used to identify ideal ablation targets with 3D mapping in patients undergoing AVNRT ablation. PREDICTORS OF THE EXTENT OF BORDER ZONES OF ATRIAL LOW VOLTAGE AREA IN PERSISTENT ATRIAL FIBRILLATION Hirotaka Muramoto, MD, Koji Higuchi, MD, Shinsuke Iwai, Chisashi Toya, Hiroshi Tsunamoto, MD, Takanobu Ozawa, MD, Keiko Araki, Kuniaki Nakano, Takayuki Onishi, Isshi Kobayashi, Yuko Onishi, Yasuhiro Sato, Shigeo Umezawa, Akihiro Niwa and Kenzo Hirao, MD. Hiratsuka Kyosai Hospital, Kanagawa, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: Atrial fibrosis identified as sites of bipolar low voltage electrogram (<0.5mV) and its border zones (0.5mV to 1.0mV) were reported as an important substrate of focal and reentrant activity in persistent atrial fibrillation (AF). Objective: We aimed to evaluate the correlation between the extent of border zones of low voltage area and patient characteristics in persistent AF. Methods: Consecutive patients with persistent AF who underwent catheter ablation were evaluated. High-density bipolar voltage mapping was carried out using Pentaray TM catheter during sinus rhythm after pulmonary vein isolation. We calculated the area of border zones of low voltage area defined as sites of middle to low voltage electrogram (0.5mV to 1.0mV) traced using CARTO 3D mapping system (Figure). Results: A total of 91 patients (68 males, median age 68.0 years) were evaluated. The extent of border zones (median 13.6 cm 2, 3.8 to 26.5) had significant correlations with age (r=0.517, p<0.001) and left atrial volume measured by helical computed tomography (r=0.323, p=0.002) while It had negative correlation with height (r=-0.232, p=0.027), weight (r=-0.239, p=0.023) and body surface area (r=-0.257, p=0.014). Conclusion: The extent of border zones of atrial low voltage area had significant correlations with age, low body weight, and left atrial volume in patients with persistent AF. These findings might be reasons why elderly patients with low body weight have more AF recurrence after catheter ablation. B-PO CT-MERGE IMAGING GUIDED ABLATION FOR VENTRICULAR ARRHYTHMIAS ORIGINATING FROM THE LEFT VENTRICULAR PAPILLARY MUSCLES Dong Chang, MD, PhD. First Affiliated Hospital of Dalian Medical University, Dalian, China Background: The anatomically complicated structures of the left papillary muscles (LPMs) renders the ablation of ventricular arrhythmias (VAs) originating from this region more challenging. Intracardiac echocardiography (ICE) can visualize the real-time LPMs and improve ablation. However, the higher cost of ICE has constrained its wide application in China. Objective: The present study was aimed to investigate the

29 S516 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 effect of catheter ablation guided by CT-merge image on the ventricular arrhythmias from the left ventricular papillary muscles. Methods: 19 patients who underwent catheter ablation for with VAs admitted in our hospital from 2009 to 2016 were enrolled in the present study. The first 13 patients (control group) underwent ablation by 3-dimensional (3D) map guided by CARTO system. The latter 6 patients (merge group) underwent ablation by CTmerge map. In merge group, we built the ostium of left and right coronary artery, or tricuspid valve and coronary sinus. Then we merged with cardiac CT. The generated CT-merge image could show LPMs clearly and guide catheter for mapping and ablation. Results: The procedure time and ablation duration in merge group were significantly shorter than control group. After ablation, 10/13 in control group and 6/6 in merge group were free from VEs. All patients were followed up 1 years, 12/15 (80%) patients in control group and 7/7 (100%) in merge group were free from Vas without arrhythmias. Conclusion: CT-merge imaging is a useful tool for guiding ablation of VAs originating from the LPMs. B-PO IDENTIFICATION OF THE BEST ABLATION TARGET AND ITS RELATIONSHIP WITH MID-DIASTOLIC ACTIVITY IN RE-ENTRANT INTRA-ATRIAL TACHYCARDIA Giuseppe Stabile, MD, Matteo Anselmino, MD, Ignacio Garcia- Bolao, PhD, Marco Scaglione, MD, Francesco Solimene, MD, Antonio De Bellis, MD, Marco Pepe, MD, Alfonso Panella, MD, Federico Ferraris, MD, Maurizio Malacrida, Francesco Maddaluno, MSc, Fiorenzo Gaita, MD and Antonio De Simone, MD. Clinica Mediterranea, Naples, Italy, Division of Cardiology, Department of Internal Medicine, University of Turin, Turin, Italy, Clinica Universitaria de Navarra, Pamplona, Spain, Hospital of Asti, Asti, Italy, Casa Cura Clinica Montevergine, Lab Elettrofisiologia, Mercogliano, Italy, Clinica San Michele, Maddaloni (CE), Italy, Molinette Hospital, Città della Salute e della Scienza, Turin, Italy, Boston Scientific, Milan, Italy, Città della Salute e della Scienza - Università degli Studi di Torino, Torino, Italy Background: Intra-atrial re-entrant tachycardias (IART) may constitute a diagnostic and therapeutic challenge. Previous studies suggested that the ideal ablation site seems to be an area of slow conduction where mid-diastolic electrograms (EGM) s can be recorded. Objective: We evaluated the ability of an ultra-high mapping system to identify the most convenient ablation target (RAT) in terms of the narrowest area to transect in order to interrupt the re-entry. Methods: Twenty-four consecutive patients were enrolled with a total of 26 IARTs (mean EGMs for each map=19.023±11.197, mean mapping time=25±11 minutes). The Rhythmia mapping system was used to identify the RAT all IARTs. Results: In 18 cases (69%) the RAT matched the mid-diastolic phase of the re-entry whereas in 8 cases (31%) the RAT differed. In these patients, the mid-diastolic tissue in the active circuit never represented the area with the slowest conduction velocity (CV) of the re-entry. While the tachycardia cycle length duration (TCL) and CV at the RAT were comparable between the two groups of patients, the mean CV of the remaining circuit was significantly slower in the group in which the RAT did not match the mid-diastolic phase of the re-entry (p=0.007). In 25 out of 26 IARTs, ablation was successfully performed at the RAT. Conclusion: Identifying the most convenient ablation target in challenging IARTs by means of high-density representation of the wave-front propagation of the tachycardia seems feasible and effective. In one third of cases this approach identifies an area that differs to the mid-diastolic corridor. B-PO IS THE CRYOABLATION AN EFFECTIVE TREATMENT FOR PAROXYSMAL AF PATIENTS WITH STRUCTURAL HEART DISEASE? CLINICAL OUTCOMES FROM MULTICENTER OBSERVATIONAL PROJECT Claudio Tondo, MD, PhD, Giovanni Battista Perego, Luigi Padeletti, MD, Giuseppe Arena, MD, Roberto Verlato, Giulio Molon, Antonio Curnis, MD, Massimiliano Manfrin, Giuseppe Allocca, Maurizio Lunati, Giovanni Rovaris and Saverio Iacopino. Centro Cardiologico Monzino, Milano, Italy, Istituto Auxologico Italiano, Milano, Italy, Multimedica Holding S.p.A., Sesto San Giovanni, Italy, Ospedale Massa, Massa Carrara, Italy, ULSS 15, Camposampiero, Italy, Ospedale Sacro Cuore Don Calabria, Negrar, Italy, University of Brescia Medical School, Brescia, Italy, Ospedale Centrale, Bolzano, Italy, Santa Maria della Misericordia, Conegliano, Italy, Ospedale Niguarda, Italy, Arrhythmology Department GVM Care&Research, Lamezia Terme, Italy Background: Complete pulmonary vein isolation (PVI) is the best documented target for catheter ablation of paroxysmal AF. Better rhythm outcome and lower procedure-related complications can be expected in patients in the absence of significant structural heart disease (SHD). Objective: to assess and compare outcome for an index CryoBalloon (CB) PVI in paroxysmal AF population with and without SHD. Methods: From April 2012 to May 2017, 1337 paroxysmal AF patients (73% male, 59 ± 11 years; mean left atrial diameter 41±6 mm) underwent CB-PVI. Data were collected prospectively in the framework of the One Shot TO Pulmonary vein isolation (1STOP) project, involving 36 Italian Cardiologic Centers. All patients were divided into two groups according to the presence SHD. According to current ESC guidelines, SHD was defined as Left Ventricular (LV) systolic or diastolic dysfunction, longstanding hypertension with LV hypertrophy, and/or other structural heart disease. Data on procedural outcomes and long term freedom of AF recurrence were evaluated. Results: SHD was present in 244/1337 (18%) cases. Patients with SHD were older than those without SHD (63 ± 9 vs 58±11; p<0.01); they were more frequently male (79% vs 69%; p=0.04), had lower functional capacity (NYHA class >1 30% vs 12%; p<0.001) and had higher cardioembolic risk (CHA 2 DS 2 -Vasc score 2: 62%% vs 38%; p<0.001). Moreover, the presence of SHD was associated to lower left ventricular ejection fraction (57 ± 7 vs. 60 ± 7; p<0.001) and higher left atrial diameter(44 ±6 vs. 40±5 mm; p<0.001) and area (23 ± 5 vs. 21± 5; p<0.001 cmq). The 2 groups showed comparable procedure, fluoroscopic times and acute success rate (respectively, on overall population: ± 46.5 minutes, 28.8 ± 15.1 minutes and 98.5%). The rate of acute procedural complications was 5.1% (2,4% were Transient Diaphragmatic Paralysis) with no significant differences between the 2 groups. The 12month freedom of AF recurrence probability after a single CB-PVI was 78% and 77% in patients with and without SHD, respectively, (p =0.62). Conclusion: In our multicenter experience, the 18% of patients treated with index Cryoballoon-PVI suffered from SHD. CB- PVI was safe and effective in paroxysmal AF patients with and without SHD.

30 Poster Session V S517 B-PO THE CLINICAL DIFFERENCE ABOUT SECOND SESSION ABLATION AFTER CRYOBALLOON AND RADIOFREQUENCY PULMONARY VEIN ISOLATION FOR PAROXYSMAL ATRIAL FIBRILLATION Yukihiro Inamura, MD, Junichi Nitta, MD, Takashi Ikenouchi, MD, Kazuya Murata, MD, Tatsuhiko Hirao, MD, Tomomasa Takamiya, MD, Nobutaka Kato, MD, Akira Sato, MD, Yoshihide Takahashi, MD, Masahiko Goya, MD and Kenzo Hirao, MD. Japanese Red Cross Saitama Hospital, Saitama, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: Previous studies reported that Cryoballoon-based pulmonary vein (PV) isolation (Cryo-PVI) was noninferior to radiofrequency-based PV isolation (RF-PVI) for the patients with paroxysmal atrial fibrillation (AF). In RF-PVI, the isolation area can be freely determined in accordance with operator. Extensive PV isolation can isolate PV antrum and a part of left atrium (LA) together. On the other hand, Cryo-PVI isolate limited PV area. The clinical difference about second session ablation after Cryoand RF-PVI was unknown. Objective: We evaluated the clinical difference about second session ablation after Cryo- and RF-PVI for paroxysmal AF. Methods: For this prospective observational study, we enrolled 881 patients ablated with the second generation cryoballoon (Cryo-group) and 496 with radiofrequency catheter (RF-group) for paroxysmal AF between January 2013 and June 2017 at our institution. In RF-group, PV isolation underwent extensively, including PV antrum and a part of left atrium posterior wall. After PV isolation, if non-pv AF foci were documented, we added ablation with radiofrequency catheter in both group. The recurrence was defined AF or atrial tachycardia (AT) documented over 30 seconds after a 3-months blanking periods. Results: All patients obtained complete PV isolation. After a median follow-up of 13.7 month, arrhythmia-free survival rates after single catheter ablation procedure without any antiarrhythmic drugs were 88.1% and 84.9% at 1 year in Cryoand RF-group (P=0.32), and 62 and 81 patients underwent second session ablation in Cryo- and RF-group, respectively. All of each PV reconnection was observed more frequently in RF-group than in Cryo-group (left superior PV; 46.9% and 14.5% P<0.01, left inferior PV; 34.5% and 11.2% P<0.01, right superior PV; 40.7% and 22.6% P=0.03, right inferior PV; 35.8% and 19.3% P=0.04). Concerinng non-pv AF foci, LA foci were shown more frequently in Cryo-group than RF-group (27.4% and 7.4% P<0.01). Other non-pv foci, there was no significant prevalence between two groups. Conclusion: In our study, Cryo-PVI was noninferior to RF-PVI for paroxysmal AF. Cryo-PVI had less LA-PV reconnection than RF-PVI, however extensive PV isolation may eliminate a part of LA AF foci. B-PO ASSOCIATION BETWEEN LEFT ATRIAL ENLARGEMENT AND SUBSEQUENT THROMBOEMBOLIC EVENTS IN NON- VALVULAR ATRIAL FIBRILLATION PATIENTS WITH LOW CLINICAL EMBOLIC RISK Min Soo Cho, MD, Kee-Joon Choi, MD, Ungjeong Do, Yu-na Kim, JongMin Hwang, Jun Kim, MD, Gi-Byoung Nam, MD and You-Ho Kim, MD. Asan Medical Center, Seoul, Korea, Republic of Background: The current thromboembolic risk stratification of non-valvular atrial fibrillation (NVAF) does not incorporate the parameters from transthoracic echocardiography (TTE). Objective: We hypothesized that left atrial enlargement (LAE) on TTE could discriminate those who necessitate anticoagulation therapy among NVAF patients with low clinical embolic risk. Methods: A total of 4,929 NVAF patients (mean 54.9 years, 89.1% male) with low clinical embolic risk (CHA2DS2-VASc score 0-1) were analyzed. LAE was classified as mild ( 41mm in male; 39mm for female) and moderate-severe ( 47mm in male; 43mm in female) according to the guideline. The main study outcome was rates of thromboembolic events (ischemic stroke and systemic embolism). Results: Mild and moderate-severe LAE was diagnosed in 29.0% and 30.8%, respectively. The patients with moderatesevere LAE showed the higher incidence of thromboembolic events than those with mild LAE or no LAE at 3 years of followup. (4.0% vs. 1.9% vs 1.6%, respectively, p<0.001). After multivariable adjustment, patients with moderate-severe LAE were at higher risk of the thromboembolic event (HR 2.23, 95% CI , p<0.001) compared to no LAE. The patients with low embolic risk and moderate-severe LAE showed similar rates of thromboembolic events compared to those with CHA 2 DS 2 - VASs score 2 and mild or no LAE (4.0% vs 3.9%, p=0.484). Conclusion: In NVAF patients with low clinical embolic risk, moderate-severe LAE on TTE was a significant predictor of thromboembolic events. B-PO SINUS NODE DYSFUNCTION REVERSAL AFTER CATHETER ABLATION OF ATRIAL FIBRILLATION: SHOULD ABLATION AND NOT PACEMAKER IMPLANTATION BECOME FIRST-LINE THERAPY? Alexandra Marx, Boris A. Hoffmann, MD, Katrin Steinbach, Blanca Quesada Ocete, MD, Karsten Bock, MD, Björn Lange, Peter Seidel, Volker Schmitt, Hanke Mollnau, MD, Thomas Rostock, MD and Torsten Konrad, MD. Mainz, Germany, University Heart Center, Hamburg, Germany, Johannes Gutenberg-University, Department of Cardiology, Cardiology II / Electrophysiology, Mainz, Germany, University Medical Center Mainz, Mainz, Germany, Center of Cardiology, Department of Cardiology II/Electrophysiology, University Hospital Mainz, Mainz, Germany, University Hospital Mainz, Mainz, Germany, II: Medical Clinic, Department for Electrophysiology, Johannes- Gutenberg University, Mainz, Germany Background: In patients with atrial fibrillation (AF), sinus node dysfunction (SND) is common and leads to a limited applicability of antiarrhythmic drugs. Pacemaker (PM) implantation is still the most widely used treatment in these patients. Objective: The aim of this study was to evaluate the impact of AF ablation to facilitate sinus node function recovery and to avoid permanent PM implantation in an unselected cohort of AF patients with SND. Methods: We prospectively included 80 consecutive patients with SND and AF (44% female). The mean age was 72.6±8.6y. In all patients, significant pauses >3s due to SND were documented by Holter ECG. 17 patients (21%) suffered from persistent AF, 63 patients (79%) had paroxysmal AF. All patients underwent AF ablation (paroxysmal: pulmonary vein isolation, persistent: stepwise ablation). In case of recurrence, re-ablation procedure was intended. Only in patients suffering from

31 S518 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 recurrent pauses with syncope or the need for antiarrhythmic drug therapy after ablation, PM implantation was performed. Results: After a mean follow-up of 46.8±25.5 months, only 14 (18%) patients required PM implantation. These patients were more likely to suffer from persistent AF (50% vs. 15%, p<0.01), had more often recurrences of AF after first ablation (64% vs. 44%, p=0.024) or needed an amiodarone treatment (43% vs. 12.5%, p<0.01). In patients with paroxysmal AF, PM implantation was required in only 11% of patients. During follow up, no patient without PM suffered from syncope or underwent PM implantation later. Conclusion: PM implantation can be prevented in the majority and even in older AF patients with sinus node dysfunction. Predictors for a favorable clinical outcome without PM implantation were the presence of paroxysmal AF, no arrhythmia recurrence after ablation and no use of amiodarone. Thus, catheter ablation has the potential to become the primary therapeutic option in AF patients with SND and thereby, avoiding permanent PM implantation. B-PO THE 30 SECOND GOLD STANDARD DEFINITION OF ATRIAL FIBRILLATION AND ITS RELATIONSHIP WITH SUBSEQUENT ARRHYTHMIA PATTERNS Jonathan S. Steinberg, MD, FHRS, Heather O Connell, MS, Shelby Li and Paul D. Ziegler. Summit Medical Group, Short Hills, NJ, Medtronic, Saint Paul, MN, Medtronic, Mounds View, MN Background: The Heart Rhythm Society consensus statement arbitrarily defines atrial fibrillation (AF) ablation failure as any episode 30s. However, if brief AF events are not correlated to longer events, the rationale for this endpoint is questionable. Objective: To determine the impact of AF episode duration threshold on AF incidence and burden. Methods: Consecutive pacemaker registry patients with devicedetected AF and follow-up >30 days were analyzed. AF patterns were calculated for various first episode AF duration thresholds (30sec, 2min, 6min, 3.8h, 5.5h, 24h) selected based on consensus statements, established evidence for stroke risk, and device capabilities. Freedom from AF post-device implant using these various AF episode duration thresholds was assessed. Results: Among 615 pacemaker patients (age 72.0±11.8yr, 54.2% male, follow-up 3.7±2.2yr) with device-detected AF, 599 had 1 AF episode of 30s duration (median: 22 episodes). At 12 months, freedom from AF was 25.5%, 30.1%, 34.6%, 52.6%, 56.5%, and 73.1% for duration thresholds of 30s, 2min, 6min, 3.8h, 5.5h, and 24h, respectively. Of patients with a 1st episode of 30s to 2mins, 70.3% and 35.8% did not have subsequent atrial arrhythmia events 3.8h and 2 mins, respectively, by 180 days (Figure). Conclusion: Small differences in AF episode duration can significantly affect the perceived incidence of AF and impact reported outcomes such as AF ablation success. An initial AF episode of 30s was often associated with no subsequent AF events. B-PO ASSOCIATION OF PR INTERVAL WITH RENAL FUNCTION: INSIGHTS FROM THE LIFE-ADULT-STUDY Jelena Kornej, MD, MSc, Samira Zeynalova, Joachim Thiery, Ralph Burkhardt, Markus Loeffler and Daniela Husser, MD. Heart Center Leipzig, Leipzig, Germany, Institute for Medical Informatics, Statistics, and Epidemiology (IMISE), University of Leipzig, Leipzig, Germany, Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Leipzig, Germany, Leipzig University Heart Center, Leipzig, Germany Background: Renal impairment is associated with poor prognosis in the setting of atrial fibrillation (AF). Recently, we demonstrated association between PR interval prolongation with left atrial diameter and cardiac biomarkers, indicating subclinical cardiac impairment. However, the role of renal function in probands with PR interval prolongation is understudied. Objective: The aim of this study was to investigate the association between PR interval length (short, normal, prolonged) and renal function in epidemiological cohort. Methods: The LIFE-Adult-Study is a population-based cohort study, which has recently completed the baseline examination of randomly selected participants from Leipzig, a major city with inhabitants in Germany. In the current crosssectional analysis, individuals 40 years with no overt heart disease, no history of antiarrhythmic drugs if sinus rhythm in ECG were compared with individuals with AF. Results: The study population comprised individuals (median age 60 (IQR 50-69) years, 48% males) with complete ECG and laboratory data. The prevalence of individuals with short, long PR intervals and AF was low (201 individuals (5%), 235 (5.8%), 66 (1.6%), respectively). We found significant differences in egfr levels between all groups (p<0.001). Women had significantly worse renal function than men (median/ IQR 77 (65-92) and 81 (66-96) ml/min/1.73m², respectively). While individuals with short PR and normal PR intervals had the highest egfr levels (mean/iqr 82 (69-97) and 80 (67-94) ml/ min/1.73m², respectively), we observed significant impairment in renal function in the groups with PR interval prolongation and AF (mean/iqr 70 (57-85) and 60 (48-73) ml/min/1.73m², p<0.001) in the whole population. However, these findings were also observed in both men and women, if analyzed separately. Conclusion: Impairment in renal function was observed in probands with PR interval prolongation and with AF. These findings confirm the role of cardio-renal axis in AF patients

32 Poster Session V S519 as well as indicate that PR interval prolongation might be considered as intermediate phenotype for AF. Larger longitudinal studies are needed to prove these results. B-PO ICE OR FIRE? COMPARISON OF SECOND-GENERATION CRYOBALLOON ABLATION AND RADIOFREQUENCY ABLATION IN PATIENTS WITH SYMPTOMATIC PERSISTENT ATRIAL FIBRILLATION AND AN ENLARGED LEFT ATRIUM Ersan Akkaya, Alexander Berkowitsch, PhD, Sergej Zaltsberg, Harald Greiß, Dr., Johannes Sperzel, MD, Christian Hamm, MD, Thomas Neumann, MD and Malte Kuniss, MD. Kerckhoff Heart Center, Bad Nauheim, Germany, Kerckhoff Herart Centre/Cardiology, Bad Nauheim, Germany, Kerckhoff-Klinik, Bad Nauheim, Germany, Kerckhoff - Klinik Heart Center, Bad Nauheim, Germany, Kerckhoff Klinik, Cardiothoracic Centre, Bad Nauheim, Germany, Kerckhoff-Clinic, Dept of Cardiology, Bad Nauheim, Germany Background: It is unclear whether the cryoballoon technique can be used in persistent atrial fibrillation (AF), particularly in cases of left atrial (LA) enlargement Objective: The aim of this study was to compare arrhythmia recurrence rates after catheter ablation using second-generation cryoballoon (CB-Adv) or radiofrequency (RF) ablation in patients with persistent AF and LA dilatation. Methods: This observational cohort study involved patients with persistent AF and LA dilatation who underwent initial RF or CB-Adv ablation as index procedure at our institution since May Patients (n=451) with LA enlargement (LA area 20 cm 2 ) were compared using a propensity-score-matching algorithm: 111 patients were treated with CB-Adv, and 111 patients were treated with RF. In addition to pulmonary vein isolation (PVI), a roof line (RL) with bidirectional conduction block was created in 48 patients in the CB-Adv group and 49 patients in the RF Group. Results: Propensity score matching was accurate, so the baseline variables of the two groups did not differ significantly. During midterm follow-up, arrhythmias recurred in 47 patients in the RF and 32 patients in the CB-Adv group (p=0.20), with no significant differences in AF (36 vs. 32, p=0.66) but fewer instances of LA tachycardias (LATs) after PVI with CB-Adv (11 vs. 0, p<0.01). LAT recurrence was associated with the presence of a RL (9 with vs. 2 without RL, p<0.01). Among patients in whom a RL was created, arrhythmia recurrence rates were higher in the RF than in the CB-Adv group (55.1% vs. 20.8%, p<0.01) Conclusion: We observed no significant difference in AF recurrence rates between the CB-Adv and RF groups over a two-year follow-up period, but LAT recurrence rates were more frequently in the RF group, especially when RLs additionally were created. Of all patients in whom a RL was created, arrhythmia recurrence rates were lower in the CB-Adv group. B-PO TIME-TO-EFFECT GUIDED PULMONARY VEIN ISOLATION UTILIZING THE THIRD-GENERATION VERSUS SECOND GENERATION CRYOBALLOON - ONE YEAR CLINICAL SUCCESS Christian H. Heeger, MD, Erik Wißner, MD, PHD, FHRS, Andreas Rillig, Shibu Mathew, Bruno Reissmann, MD, Christine Lemes, MD, Tilman Maurer, MD, Thomas Fink, MD, Osamu Inaba, MD, Francesco Santoro, MD, Feifan Ouyang, MD, Karl- Heinz Kuck, MD and Andreas Metzner, MD. AK St. Georg, Hamburg, Germany, Division of Cardiology, University of Illinois at Chicago, USA, Chicaco, IL Background: The second-generation cryoballoon (CB2) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging and reproducible clinical outcome data. The latest-generation cryoballoon (CB3) incorporates a 40% shorter distal tip, thus allowing for an increased rate of PVI real-time signal recording and facilitating individualized ablation strategies taking the time-to-effect (TTE) into account. However, if this characteristic translates into favorable clinical success was not evaluated yet. Objective: Here we investigated the one-year clinical success after CB3 in comparison to CB2 based-pvi. Methods: 110 consecutive patients with paroxysmal or shortstanding persistent atrial fibrillation (AF) underwent CB2 (n=55 patients) - or CB3 (n=55 patients) -based PVI. The freeze-cycle duration was set to TTE+120 seconds if TTE could be recorded, otherwise a fixed freeze-cycle duration of 180 seconds was applied. Results: A total of 217/218 (99%, CB3) and 217/217 (100%, CB2) pulmonary veins (PV) were successfully isolated. The realtime PVI visualization rate was 69.2% (CB3) and 54.8% (CB2; p=0.0392). The mean freeze-cycle duration was 194±77sec. (CB3) and 206±85sec. (CB2; p=0.132), respectively. During a median follow-up of 409 days (interquartile range , CB3) and 432 days (interquartile range , CB2) 73.6% (CB3) and 73.1% of patients (CB2) remained in stable sinus rhythm after a single procedure (p=0.806). Conclusion: A higher rate of real-time electrical PV recordings was seen using the CB3 as compared to CB2. There was no difference in the 1-year clinical follow-up. B-PO CHA 2 DS 2 -VASC SCORE PREDICTS THE LONG-TERM RISK OF MAJOR CARDIOVASCULAR EVENTS AND MORTALITY IN ATRIAL FIBRILLATION PATIENTS WITH RADIOFREQUENCY ABLATION Minh Hoang Quang, MD, Chin-Yu Lin, MD, Yenn-Jiang Lin, MD, PhD, Shih-Lin Chang, MD, PhD, Li-Wei Lo, MD, PhD, Yu-Feng Hu, PhD, Fa-Po Chung, MD, Ting-Yung Chang, MD, Simon Salim, MD, Rubiana Sukardi, Vu Van Ba, MD, TingChun Huang, Chieh-mao Chuang, Cheng-I Wu, Ling Kuo, Hsing-Yuan Li, PhD, Jennifer Jeanne B. Vicera, Chye-Gen Chin, Chun Chao Chen and Shih-Ann Chen, MD. Heart Rhythm Center and Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital/ Nationa, Taipei City, Taiwan, Taipei Veterans General Hospital, Taipei, Taiwan, Fellow in Training - Taipei Veteran General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei City, Taiwan, Taipei, Taiwan Background: The long-term morbidity and mortality of catheter ablation (CA) in patients (pts) with AF remain unclear. Objective: We investigated the impact of CA on the long-term risk of cardiovascular (CV) events and mortality in AF pts with CA. Methods: A total of 1036 AF pts underwent CA were enrolled retrospectively utilizing the database of our hospital from to investigate the primary outcomes of major CV events and total mortality not related to the procedure complications. We divided into 4 groups according to the CHA2DS2-VASc score: (1)score=0, (2)score=1, (3)score=2, (4)score 3, compared the differences of baseline characteristics between pts with or without the CV events and mortality. Results: During a very long-term follow-up of 8±3 years (up to 14 years), a total of 7 mortalities (non-cv related), and 27 major CV events were identified with an event rate of 0.3% per

33 S520 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 year-person. Pts with CV events were higher CHA 2 DS 2 -VASc score(p<0.001). We demonstrated an association between scores and the major CV events(table), with hazard ratio [HR]=10.1 for score=1, HR=15.1 for score=2, HR=24.3 for score 3, compared to pts with score=0 as the reference group. The event free survival of major CV events and mortality were poor in pts with higher score(figure). Conclusion: The CHA 2 DS 2 -VASc scores could be used to predict major CV events and mortality for pts with AF undergoing CA. The most common CV events were CAD and stroke in this cohort with very long-term follow-up. The CA might reduce the annual incidence of stroke in AF population(0.1% vs % with mean CHA 2 DS 2 -VASc score 1.7) but we observed a higher incidence of coronary related events with very long-term followup. B-PO IMPACT OF LEFT ATRIUM SIZE ON PULMONARY VEIN ISOLATION STRATEGY : CRYOBALLOON OR RADIOFREQUENCY CATHETER ABLATION Takashi Ikenouchi, MD, Junichi Nitta, MD, PhD, Giichi Nitta, MD, Kazuya Murata, MD, Tatsuhiko Hirao, MD, Tomomasa Takamiya, MD, Nobutaka Kato, MD, Yukihiro Inamura, MD, Akira Sato, MD, Yoshihide Takahashi, MD, PhD, Masahiko Goya, MD, PhD and Kenzo Hirao, MD. Japanese Red Cross Saitama Hospital, Saitama, Japan, Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo, Japan Background: Pulmonary vein isolation (PVI) using the 2 nd - generation cryoballoon has become effective strategy for the treatment of atrial fibrillation (AF). The types of AF, such as paroxysmal, persistent, and long standing AF, are important factors of recurrence after PVI. However left atrium size is also known to have relevance to clinical outcome of PVI. Objective: In this study, we assessed the relationship between left atrial diameter (LAD) and the efficacy of PVI with cryoballoon or radiofrequency. Methods: A total of 2543 consecutive AF patients underwent their first PVI from January 2012 to August 2017, and retrospectively analyzed. By using the echocardiography, LAD was measured in long-axis view, and the patients were divided into two groups according to LAD under 40mm (small group) and over 40mm (large group). The patients in each groups were matched according to propensity scores in a logistic regression model to adjust for age, AF type, non-pv foci and LA size in order to reduce selection bias, and the efficacy of ablation with cryoballoon (CB) and radiofrequency (RF) were compared. Results: In small group (n=1140), mean LAD were 33±5mm in CB group and 33±5mm in RF (p=0.66), mean age were 64±10 in CB group and 64±10 in RF (p= 0.85), and the percentage of paroxysmal, persistent and long-standing AF were 82%, 14%, 2% in both methods (p=0.15). In large group (n=378), mean LAD were 44±4mm in CB group and 44±3mm in RF (p=0.41), mean age were 65±10 in CB group and 65±9 in RF (p= 0.70), and the percentage of paroxysmal, persistent and long-standing AF were 55%, 38%, 7% in both methods (p=0.93). The patients with small LAD who were treated with cryoballoon had significantly higher AF-free survival rate after procedure than patients treated with radiofrequency (2-years Kaplan-Meier event rate, 82.6% vs 77.9%; p=0.04). On the other hand, in large group there was no significant difference in rate of freedom from AF recurrence between both methods (2-years Kaplan-Meier event rate, 71.3%% vs 70.0%; p=0.92). Conclusion: In patients with LAD under 40mm, cryoballoon might be effective methods for PVI regardless of the AF type. The success rate of PVI with cryoballoon and radiofrequency were comparable in patients with LAD over 40mm. B-PO PROGNOSTIC SIGNIFICANCE OF IMMEDIATE ARRHYTHMIA RECURRENCES AFTER INTRACARDIAC CARDIOVERSION IN PATIENTS SUBSEQUENTLY UNDERGOING PERSISTENT ATRIAL FIBRILLATION ABLATION Yuhi Fujimoto, MD, Meiso Hayashi, MD, Eiichiro Oka, Kenta Takahashi, MD, Hiroshi Hayashi, Teppei Yamamoto, MD, PhD, Kenji Yodogawa, MD, Yu-Ki Iwasaki, MD and Wataru Shimizu, MD. Nippon Medical School, Tokyo, Japan, NIppon Medical School, Tokyo, Japan, Tokyo, Japan, Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan, Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan Background: Immediate recurrences of atrial fibrillation (IRAF) frequently occurs after successful direct-current cardioversion (CV), its prognostic significance, however, have not been sufficiently studied. Objective: The purpose of the present study was to examine a role of IRAF in predicting arrhythmia recurrences after a radiofrequency catheter-based atrial fibrillation (AF) ablation. Methods: In 203 consecutive patients (63±10years) who underwent an initial catheter ablation for persistent AF, intracardiac-cardioversion was performed at the beginning of the procedure to determine the presence or absence of IRAF, which was defined as a reproducible AF recurrence within 90 seconds after restoration of sinus rhythm by CV. Atrial arrhythmia recurrences, as well as clinical backgrounds and laboratory data were compared between the patients demonstrating IRAF and the patients without IRAF. Results: IRAF was observed in 73 patients (36%) and 94% of its triggers arose from inside the pulmonary veins. During a mean follow-up period of 642±440 days after the ablation, atrial arrhythmia recurrences were significantly less observed in IRAF patients than in non-iraf patients (Figures). Multivariate analysis revealed the presence of IRAF (HR, 0.429, 95%CI , P=0.01) was a predictor of arrhythmia recurrences, along with left atrial volume index (HR, 1.022, 95%CI , P=0.04) and echocardiographic E/E (HR 1.091, 95%CI , P=0.04). Conclusion: IRAF was seen in about one-third of the patients with persistent AF, and mostly triggered by PV ectopies. PV isolation for IRAF patients might be effective in suppressing AF.

34 Poster Session V S521 B-PO B-PO EFFICACY OF ADDITIONAL ABLATION OF THE LEFT ATRIAL POSTERIOR WALL ISOLATION AND SUPERIOR VENA CAVA ISOLATION IN PATIENTS WITH RECURRENCE OF ATRIAL FIBRILLATION AFTER CRYOBALLOON ABLATION Hideko Toyama, MD, PhD and Koichiro Kumagai. Fukuoka Sanno Hospital, Fukuoka, Japan Background: Pulmonary vein (PV) isolation with the secondgeneration cryoballoon is widely performed in the patients with paroxysmal atrial fibrillation (AF). However, the next ablation strategy is controversial during the second procedure in patients with AF recurrence. Objective: To evaluate the outcomes after cryoablation and the efficacy of additional ablation of the left atrial (LA) posterior wall isolation and superior vena cava (SVC) isolation in patients with AF recurrence. Methods: A total of 333 patients with paroxysmal AF underwent PV isolation using cryoballoon (Arctic Front Advance cryoballoon, Medtronic, Inc.). LA voltage maps were created during sinus rhythm. Low-voltage areas (defined as under 0.5 mv) were found in 20 (6%) patients. In patients with AF recurrence after the first procedure, a second procedure was recommended. During the second procedure, if PV reconnections were found, re-pv isolation was performed using an irrigated radiofrequency ablation catheter. Subsequently, roof and floor linear ablation isolating the LA posterior wall was additionally performed. SVC isolation was always performed in all patients. If other non-pv foci were identified, ablation of the triggers was performed. Results: During 26±3 months of follow-up, 56 (17%) patients had AF recurrence. Low-voltage areas were observed in 7 (13%) of 56 patients with AF recurrence and 15 (5%) of 277 patients without AF recurrence (P=NS). Among patients with AF recurrence, 33 patients underwent a second procedure. PV reconnections were observed in 38/132 (29%) PVs (left superior: 11, left inferior: 10, right superior: 5, right inferior PV: 12). New non-pv foci were occurred from SVC in two and the posterior LA in one, however, these triggers were eliminated after the posterior LA isolation and SVC isolation. The LA posterior wall and SVC were successfully isolated in all patients. Other non- PV focus from LA appendage was identified and ablated in one patient. After a second procedure, 29 of 33 patients had no recurrence of AF, and AF-free rate increased to 92%. Conclusion: Low-voltage areas may not be related to AF recurrence. In patients with AF recurrence after cryoablation, additional ablation of the LA posterior wall isolation and SVC isolation may be effective. INCIDENCE AND PREDICTORS OF LATE PULMONARY VEIN RECONNECTION AFTER ABLATION INDEX-GUIDED ABLATION IN PATIENTS WITH PERSISTENT ATRIAL FIBRILLATION Ahmed A. Hussein, Moloy Das, MBBS, Graeme J. Kirkwood, Baptiste Maille, Stefania I. Riva, Maureen Morgan, Christina Ronyane, Akanksha Gupta, Matthew Shaw, Andrea Natale, MD, FHRS, Antonio Dello Russo, MD, Richard L. Snowdon, MBCHB and Dhiraj Gupta, MBBS, MD. Research Dept., Liverpool Heart and Chest Hospital, Liverpool, United Kingdom, Freeman Hospital, Newcastle upon Tyne, United Kingdom, Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, Centro Cardiologico Monzino, Milan, Italy, Cardiothoracic Centre, Liverpool, United Kingdom, Liverpool Heart and Chest Hospital, Liverpool, United Kingdom Background: Recent studies showed that use of regional Ablation Index (AI) targets results in improved clinical outcome following AF ablation. We hypothesized that this is due to a high rate of durable PVI. Objective: To study predictors of late reconnection (LRC) after AI-guided ablation. Methods: 40 patients (30 male, 61±8 yrs, LAd 43±5mm) underwent uncomplicated PVI with AI-guided contiguous pointby-point wide antral circumferential ablation (WACA) for drugrefractory persistent AF at 3 centers. A SmartTouch catheter was used with RF power 30-40W, irrigation 17-30ml/min, and AI targets 550 for anterior and 400 for posterior segments. All patients underwent mandatory repeat LA study after 2 months to identify LRC. All VisiTags (n=5993) were analysed offline for predictors of reconnection in a 12-segment model. Results: 4/80 WACA circles were excluded for protocol violation. LRC was seen in 11 (7%) PVs affecting 13/456 (3%) segments in 8 (22%) patients. There was no difference in minimum Contact Force, FTI, AI or Impedance Drop values between segments with or without LRC (Table). Segments with LRC had a significantly lower mean catheter tip temperature. Mean transverse diameter was significantly greater in WACA circles with LRC compared to those without LRC (27.1±8.6 vs. 20.4±5.3mm, P=0.025) but there was no difference in the number of inter-lesion gaps of >6 mm (both 1 (0-3), P=0.83). Conclusion: AI-guided ablation is associated with a high incidence of durable PVI in patients with persistent AF. Larger WACA circle size is associated with a higher incidence of late PV reconnection. The significantly lower tip temperature seen in LRC segments suggests excessive irrigation with current settings. B-PO FRAILTY AND MORTALITY IN ATRIAL FIBRILLATION Peter Hanlon, MBChB, Bhautesh Jani, PhD, Derek Thomas Connelly, MD, Barbara Nicholl, PhD, Ross McQueenie, PhD, Duncan Lee, PhD and Frances Mair, MD. University of Glasgow, Glasgow, United Kingdom, Golden Jubilee National Hospital, Glasgow, United Kingdom Background: Multimorbidity ( 2 long-term conditions (LTCs)) is associated with increased mortality in people with atrial fibrillation (AF). Frailty is associated with multimorbidity and AF may be a marker of frailty in elderly patients. The prevalence and impact of frailty in middle-older aged individuals with AF is unknown. Objective: (1) To assess the prevalence of frailty/pre-frailty in middle-older aged participants with AF. (2)To assess the impact

35 S522 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 of frailty/pre-frailty on mortality in AF. Methods: UK Biobank participants (n=502,519) aged were recruited between LTCs (n=43) identified by selfreport. Frailty defined according to frailty phenotype, comprising 5 indicators (low grip strength, weight loss, slow walking pace, exhaustion, and low physical activity). Frailty defined as 3 indicators, pre-frailty 1-2 indicators. All-cause mortality available for median 7 yrs follow-up (IQR months). Hazard ratios (HR) and 95% confidence intervals (CI) estimated associations between frailty status and all-cause mortality, controlling for age, sex, smoking status, alcohol, BMI, socioeconomic deprivation, anticoagulation status, and either cardiometabolic comorbidity (hypertension, stroke, coronary artery disease, diabetes, heart failure) or multimorbidity count. Results: 3602 AF participants had complete data for all 5 frailty indicators. Of these, 240 (7%) were frail and 1535 (43%) prefrail. Mean age 62 yrs in all 3 groups (frail/pre-frail/not-frail). All-cause mortality rate 6.5% (n=234). Participants with frailty twice as likely to die than those without, after controlling for confounders including cardiometabolic comorbidity (HR 2.28, 95% CI ) or confounders including multimorbidity (HR 2.17, 95% CI ). Pre-frailty also significantly associated with mortality, confounders including cardiometabolic comorbidity (HR 1.59, 95% CI ) or multimorbidity (HR 1.58, CI ). Conclusion: Both frailty and pre-frailty associated with mortality in middle-older aged adults with AF after controlling for sociodemographic factors, anticoagulation status and cardiovascular comorbidity or multimorbidity count. Identification of frailty could aid risk stratification in AF. B-PO LONG-TERM CLINICAL RESULTS AFTER ABLATION OF COMPLEX ATRIAL TACHYCARDIA WITH ULTRA HIGH- DENSITY 3D MAPPING Ruken Akbulak, MD, Stephan Willems, MD, Christian Meyer, Christian Eickholt and Benjamin Schaeffer, MD. University Heart Centre Hamburg, Department of Cardiology, Electrophysiology, Hamburg, Germany, University Heart Centre Hamburg, Hamburg, Germany, University Heart Centre Hamburg, Department of Cardiology, Electrophysiology, Hamburg, Germany, University Heart Center Hamburg, Hamburg, Germany Background: Mapping and ablation of atrial tachycardias (AT) remain challenging due to complex underlying substrate and localizations throughout the atria. Objective: The aim of the study was to investigate the long-term outcome of patients after ablation of AT. Methods: The first procedure with a ultra high density 3D Mapping revealed a total of 86 ATs in 63 patients, including 55% macro-reentry tachycardia (MRT), Results: 27.1 % micro-reentry tachycardia (MIT) and 8.2 % focal tachycardia. During a mean follow-up period of 227 ± 100 days, recurrent AT was observed in 14 (22.2 %) patients (Figure 1). AT was successfully eliminated in 61 (96.8 %) patients. Nine patients (9/14) underwent a second ablation with a ultra high density mapping system. Atrial tachycardia in recurrence precedure included three mitral annulus reentrant tachycardias (33.3%), one roof dependent reentrant tachycardia (11%), two cavotricuspid isthmus (CTI) dependent atrial flutters (22%) and three MIT (33.3%). The type of initial AT mechanism played an essential role in promoting the second atrial tachycardia. While MRT leads to recurrence in forms of MRT due to gaps on the ablation line. Patients with MIT have recurrence of ATs with MIT mechanism but most from different localisation. Conclusion: Ultra high-density mapping is an effective tool for accurately identifying atrial tachycardia mechanisms and guidance for ablation with high acute and long-term success even in a selected group of patients with a progressed state of disease. Whether additional lines like CTI might additional improve success rates needs to be investigated. B-PO HIGH-FIELD MRI REVEALS EARLY ATRIAL AND VENTRICULAR STRUCTURAL REMODELING IN A SHEEP MODEL OF PERSISTENT ATRIAL FIBRILLATION Caroline Cros, PhD, Alice Recalde, PhD, Fabien Brette, PhD, Philippe Pasdois, PhD, Antonio Frontera, Julie Magat, phd, Jérôme Naulin, Rémi Chauvel, Richard D. Walton, PhD, Caroline Pascarel-Auclerc, PhD, Valentin Meillet, Remi Dubois, Michel Haissaguerre, MD, PhD, Bruno Quesson, PhD, Olivier Bernus, PhD, Pierre Jais, MD and Hubert Cochet, MD MSc. L Institut de Rythmologie et Modélisation Cardiaque LIRYC - CRCTB Inserm U1045, Bordeaux-Pessac Cedex, France, L Institut de Rythmologie et Modélisation Cardiaque LIRYC - Université de Bordeaux, Pessac, France, LIRYC institute - Hôpital Haut Lévêque, Pessac Cedex, France, IHU LIRYC, Pessac, France, LIRYC Institute - Hôpital Haut Lévêque, Bordeaux-Pessac Cedex, France, Université de Bordeaux, Pessac, France, LIRYC, Pessac, France, IHU LIRYC, Bordeaux- Pessac Cedex, France, Hopital Cardiologique Haut Leveque - Université Bordeaux, Boulogne-Billancourt Cedex, France, University of Bordeaux/Inserm U1045/IHU LIRYC, Bordeaux, France, IHU LIRYC, Pessac, France, Hôpital Haut-Lévêque, Bordeaux, France, Université de Bordeaux, Bordeaux, France Background: Myocardial structural remodeling during AF is an important factor influencing clinical outcome in patients. Objective: There is a clear need to characterize structural myocardial damage in an animal model that translates into clinical practice. Methods: We developed a sheep model of persistent AF, implanted with a dual-chamber pacemaker. The atrium port induced AF by bursts of tachypacing (10Hz stimulation for 30s every 5s). To ensure AF development, sheep were monitored weekly by reviewing device logs. After 100 days of AF, animals were sacrificed and hearts were fixed with formalin mixed with gadolinium. Imaging was performed on whole hearts immersed in Fomblin, using a 9.4T MRI system, and a T1-weighted 3D sequence (200µm 3 resolution). Results: Out of 4 animals paced, 3 reached 100 days of AF. These were compared to 3 control/sham (ctl) sheep. Highfield MRI showed marked increase in LA wall thickness in the AF group. Thickness was 3.7±0.3 vs. 2.1±0.2 on the isthmus between mitral annulus and pulmonary veins (PV), 4.1±0.4 vs. 2.2±0.3 on the isthmus between mitral annulus and left appendage, and 4.3±0.5 vs. 2.6±0.4 on the posterior wall adjacent to PV. Tissue characteristics in AF sheep showed marked heterogeneity indicating interstitial fibrosis in both the atrial and ventricular myocardium, while the myocardium was

36 S523 Poster Session V much more homogeneous in ctl. The epicardial contour showed clear irregularities with instances of fat and fibrosis infiltration in the LA wall, while the transition between myocardium and epicardial fat was sharper and straight in ctl. Conclusion: High-field MRI reveals early atrial and ventricular structural remodeling in a sheep model of persistent AF. B-PO PULMONARY VEIN GAP REENTRANT ATRIAL TACHYCARDIA AFTER ATRIAL FIBRILLATION ABLATION: INSIGHT OF ELECTROPHYSIOLOGICAL FEATURES WITH HIGH-RESOLUTION MAPPING SYSTEM Seigo Yamashita, MD, Masateru Takigawa, Nicolas Derval, MD, Yuichiro Sakamoto, MD, Masaharu Masuda, Kohki Nakamura, MD, Eri Okajima, Hidenori Sato, Hirotsugu Ikewaki, Hirotsuna Oseto, Ryota Isogai, Kenichi Tokutake, Kenichi Yokoyama, Ryohsuke Narui, Mika Kato, Shin-ichi Tanigawa, Michifumi Tokuda, MD, Seiichiro Matsuo, MD, Michihiro Yoshimura, Pierre Jais, MD, Michel Haissaguerre, MD, PhD and Teiichi Yamane, MD, PhD, FHRS. The Jikei University School of Medicine, Tokyo, Japan, Hopital Cardiologique du Haut-Leveque, Pessac, France, Toyohashi Heart Center, Toyohashi, Japan, Gunma Prefectural Cardiovascular Center, Div of Cardiology, Maebashi, Japan, Shibakouen Minatoku Tokyo, Japan, Jikei University School of Medicine, Tokyo, Japan, The Jikei University School of Medicine, Japan, The Jikei University School of Medicine, Yokohama, Japan, Jikei Univ School of Med, Japan, Hôpital Haut-Lévêque, Bordeaux, France, Boulogne-Billancourt Cedex, France, Jikei Univ School of Medicine, Tokyo, Japan Background: The detailed circuit and gaps of pulmonary veingap reentrant atrial tachycardia (PV-gap AT) following atrial fibrillation (AF) ablation are sometimes difficult to identify by the conventional mapping. Objective: To examine the detail circuit and electrophysiological features of PV-gap AT using the novel high-resolution mapping system (Rhythmia ). Methods: In this multicenter study, among 198 ATs occurring after AF ablation, 25(6.9%) PV-gap ATs in 24 patients (62±12y, paroxysmal AF in 8) were analyzed with RhythmiaTM system. Results: Mean cycle length (CL) was 260±53ms with 110±25ms of the maximum P-wave duration on 12-lead ECG. Three types of PV-gap AT circuits were observed (Figure); (a) 2 gaps in 1 PV with ipsilateral circuit (n=15), (b) 2 gaps through superior and inferior PVs with ipsilateral circuit (n=6), (c) 2 gaps in 1 PV with a large circuit including opposite side of the left atrium. Rhythmia map demonstrated two distinctive entrance/ exit gaps of 8.2±3.9/8.2±4.1mm width, where showed slow conduction (0.30±0.34/0.20±0.22m/s) with fragmented (duration: 79±32/73±23ms) and low-voltage (0.28±0.31/0.28±0.35mV) signals. ATs were terminated in 20 and changed in 5 by the first RF application at the entrance or exit gap. Moreover, conduction time within the PVs (entrance-to-exit) was 125±55ms (48±19% of AT-CL), resulted in demonstrating P-wave with isoelectric line in any lead in all patients. Conclusion: This is the first report that demonstrated detailed mechanisms of PV-gap reentry with showing evident entrance/ exit gaps by using high-resolution mapping system. The circuit is variable and Rhythmia guide ablation targeting PV gap can be curative. B-PO NON-PAROXYSMAL ATRIAL FIBRILLATION MAPPING USING A NOVEL INTEGRATED MAPPING TECHNIQUE Giuseppe Ciconte, MD, PhD, Gabriele Vicedomini, MD, Wenwen Li, Jan Mangual, Kyungmoo Ryu, PHD, Massimo Saviano, Manuel Conti, Vincenzo Santinelli, MD and Carlo Pappone. I.R.C.C.S. Policlinico San Donato, San Donato Milanese, Italy, Maria Cecilia Hospital, Cotignola, Italy, Abbott, MN, St. Jude Medical, Sylmar, Saint Lucia, St. Jude Medical CRMD, Sylmar, CA, IRCCS Policlinico San Donato, Italy, San Raffaele Hospital, Dept of Cardiology EP and Cardiac Pacing, Milan, Italy, Policlinico San Donato University Hospital, San Donato Milanese Italy, Italy Background: Clinical outcomes after radiofrequency ablation (RFA) remain suboptimal in the treatment of non-paroxysmal AF. Electrophysiological mapping (EPM) may improve understanding of the underlying mechanisms. Objective: To describe the arrhythmia substrate in patients with persistent (Pers) and long-standing (LS) Pers AF using an integrated mapping technique. Methods: Patients underwent high-density EPM before and after ablation. Integrated maps characterized electrogram (EGM)

37 S524 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 cycle length (CL), stable wavefront propagation, fragmentation and bipolar voltage. Results: Among 45 non-paroxysmal AF patients (73.3% male, 59.8±11.3 years old), repetitive-regular (RR) activations were identified in 204 regions (mean CL 179.6±31.2 msec). The mean RR sites per patient was 4.4±2.4. PersAF patients (n=20) showed more RR sites (5.3±2.4 vs 3.7±2.1, p=0.03) with faster CL (166.2±29.4 vs 190.2±28.9 msec; p=0.008) and smaller surface area of fragmented EGMs (14.9±14.3% vs 27.4±16.7%, p=0.01). The post-ablation map in 27 patients remaining in AF, documented reduction of the RR activities per patient (1.5±0.7 vs 3.7±1.4, p<0.001) and area of fragmentation (22.3±16.6% vs 8.2±8.9%, p<0.001). AF termination during ablation occurred at RR sites in 17/18 patients (94%). These subjects had more RR regions ablated than those remaining in AF (4.0±2.1 vs 2.8±1.5; p=0.05). Arrhythmia freedom was higher among patients receiving 3 RR sites ablation (15/19, 78.9% vs 12/26, 46.2%; p=0.03). Conclusion: The integrated mapping technique allowed characterization of multiple arrhythmic substrates in nonparoxysmal AF, potentially serving as tool for a substratetargeted approach. and custom software (Rhythmview, Abbott). The projected rotor cores were traced onto the atrial surface geometry and ablated (SmartTouch, 25-35W). Sequential rotor mapping and ablation continued until no further rotational or focal activity was detected. LA fibrosis density and spatial distribution were analyzed by Corview software (Merisight). Results: Of 95 study pts, the median age was 61±10 yrs, 81% were male, and 73% had persistent AF. The mean LA volume was 140±20 ml. AF was present at outset in 68 pts (72%) and was induced in those with sinus rhythm. AF terminated in 61 (64%) pts during or after rotor ablation, and was cardioverted in the remainder. A total of 238 LA rotors were identified with a mean of 2.56±0.5 rotors / pt. Mean surface area of each rotor was 3±1.5 cm 2. Median regional fibrosis expressed as percent of total tissue volume within individual rotor cores was 16% (IQR 3-33%), and 92% of core areas contained at least some LGE. Rotor core areas were infrequently within dense scar (< 20%), but tended to cluster at the periphery of such scars. Conclusion: In this cohort of AF pts undergoing initial ablation, LA rotor cores were associated with fibrosis as measured by DE-MRI. Most rotors were found at the periphery of more dense confluent or patchy scar. These data may be useful in the design of novel ablation strategies. B-PO B-PO IMPACT OF DE-MRI ON ROTOR MAPPING BY FOCAL IMPULSE AND ROTOR MODULATION DURING ATRIAL FIBRILLATION ABLATION Emily Tat, Brian Vetter, Jamie Voss, MBChB and David J. Wilber, MD, FHRS, CCDS. Loyola University Medical Center, Cardiovascular Institute, Maywood, IL, Loyola University Medical Center, Chicago, IL, Loyola Univ Medical Center, Cardiovascular Institute, Maywood, IL Background: Rotor mapping by Focal Impulse and Rotor Modulation (FIRM) is a novel strategy that may improve outcomes of AF ablation by identifying focal sources that maintain AF. Delayed enhancement-magnetic resonance imaging (DE-MRI) permits analysis of myocardial fibrosis. There is currently incomplete data on the myocardial characteristics associated with rotor formation and maintenance. Objective: Through combined imaging and rotor mapping, this study evaluates the relationship between left atrial (LA) rotor formation and fibrosis. Methods: Pts undergoing initial ablation were included in this study. DE-MRI was performed in all pts prior to AF ablation. LA chamber geometry was rendered by electroanatomical mapping. FIRM mapping was conducted using a 64-pole basket catheter MAPPING AND ABLATION IN PERSISTENT AF USING THE RHYTHMIA MAPPING SYSTEM Nathaniel C. Thompson, MD, Konstantinos George Vlachos, MD, PhD, Antonio Frontera, Ghassen Cheniti, MD, Arnaud Denis, MD, Nicolas Derval, MD, Frederic Sacher, MD and Pierre Jais, MD. Hopital Haut-Leveque, Bordeaux, France, Pessac, Bordeaux, France, LIRYC Institute - Hôpital Haut Lévêque, Pessac Cedex, France, CWT Meetings & Events, Mélissa Pernot, Boulogne-Billancourt Cedex, France, CHU Bordeaux, Pessac Cedex, France, Hopital Cardiologique Du Haut- Leveque, Pessac, France, LIRYC Institute/ Bordeaux University Hospital, Bordeaux, France, Hôpital Haut-Lévêque, Bordeaux, France Background: EGM fractionation often precludes accurate analysis of the atrial substrate during AF. The Orion catheter (BosSci, MA) uses 64 electrodes with high spatial resolution and ability to minimize EGM fractionation. Objective: The objective of this study is to quantify the relationship of EGM fractionation and cycle length (CL) with clinical characteristics Methods: 16 pts with persistent AF underwent LA mapping during AF and ablation. CFAE sites were identified online over a 2.5s window. The surface area (SA) of fractionated EGMs was quantified manually. The avg CL of 10 organized beats was calculated at 10 specific sites (all quadrants) within the LA. PVI was performed, followed by the ablation of relevant substrate (including CFAE). Results: An avg of 2404 ± 1426 EGMs were analyzed per pt. There was a gradient of 56 ± 20 ms between min and max CL within the LA. Termination of AF with ablation (10/16) was associated with shorter AF duration (5 ± 4 vs 16 ± 6 mo), smaller LA vol (160 ± 39 vs 199 ± 18ml), reduced fractioned SA (15 ± 3 vs 22 ± 6%, 16 ± 4 vs 33 ±12 cm2), a larger gradient between min and max CL (63 ± 16 vs 31 ± 10ms), and a longer LAA CL (193 ± 36 vs 182 ± 24ms). AF termination required less RF delivery (42 ± 13 vs 60 ± 9 min). Correlation demonstrated an inverse relationship between CL gradient and fractionated SA (r = -.71, p <.0001). The avg CL was longest at the LA septum and shortest at the intersection of the left carina/pvs (205 ± 42 vs.169 ± 40ms; p =0.006), both near frequent areas of fractionation (fig).

38 Poster Session V S525 Conclusion: Mapping of AF with the Orion basket catheter is feasible with a small area of fractionated EGMs and may lend insight into the substrate critical for AF maintenance and more effectively guide ablation. B-PO REAL-TIME PROPAGATION VECTOR MAPPING USING A NOVEL CLOSE UNIPOLAR ELECTRODE CATHETER AND SYSTEM Hiroshi Nakagawa, MD, PhD, Atsushi Ikeda, MD, PhD and Warren M. Jackman, MD, FHRS. Heart Rhythm Univ of Oklahoma Health Sciences Center, Oklahoma City, OK, Univ of Oklahoma Health Sciences Center, Heart Rhythm Institute, Oklahoma City, OK, University of Oklahoma Health Sciences Center, Oklahoma City, OK Background: A new mapping system has been developed. Objective: To evaluate a novel catheter mapping/ablation system for real-time propagation vector mapping using a canine model. Methods: A novel 8F deflectable mapping/ablation catheter (Sphere 9, Affera) with an expandable 9mm lattice tip, containing a magnetic location sensor, 9 mini-surface electrodes (0.5mm 2 area, uniformly distributed) and a central reference electrode was evaluated in 4 closed chest dogs. The system acquires 9 close unipolar electrograms (CUE) between each of the 9 minisurface electrodes and the central reference electrode, located inside the lattice tip (no tissue contact), providing independence from electrode orientation. The system acquires an anatomical shell using the outer boundary of the lattice at each position. Using the 9 CUE, a propagation vector is constructed in realtime for each beat at each site using activation times detected on the 3 neighboring CUE with the highest dv/dt (Fig). Propagation vector mapping was performed in the right atrium (RA) during sinus rhythm and following the creation of a linear lesion on the RA free wall using the 9mm lattice tip for RF delivery. The hearts were examined histologically. Results: Fig. During sinus rhythm, the propagation vector map showed a centrifugal pattern originating from the sinus node region in 4/4 dogs. The map after linear ablation (6-8 RF delivery) identified atrial propagation around the line of block in 4/4 dogs. Histology confirmed 4/4 continuous transmural linear RF lesions. Conclusion: This novel system with 9 CUE allows real-time propagation vector mapping, accurately identifying the origin of activation and integrity of lines of block. B-PO ASSOCIATION OF ATRIAL FIBROSIS ON HIGH RESOLUTION LATE GADOLINIUM ENHANCED CARDIAC MAGNETIC RESONANCE AND DELAYED ELECTRICAL ACTIVATION IN ATRIAL FIBRILLATION PATIENTS Ling Kuo, MD, Desjardins Benoit, MD, PhD, Francis E. Marchlinski, MD and Saman Nazarian, MD, PhD, FHRS. Taipei Veterans General Hospital, Taipei, Taiwan, Hospital of University of Pennsylvania, Philadelphia, PA, The University of Pennsylvania, Philadelphia, PA Background: Physiologic mediators of the association between late gadolinium enhancement (LGE) on cardiac magnetic resonance and recurrent atrial fibrillation (AF) following ablation are unknown. Objective: To examine the association of LGE with delayed activation on endocardial electroanatomic mapping (EAM). Methods: The retrospective cohort included 20 patients (63.9 ± 9.5 years, 85% male, 95% paroxysmal) with AF, that underwent pre-procedural 3D navigator gated LGE prior to AF ablation between January and November Segmentation of the LGE extent was performed using image intensity ratio (IIR) thresholds of 1.2 for abnormal myocardium and 1.6 for dense scar; and utilizing ADAS software (Galgo Medical SL, Barcelona, Spain). Sinus rhythm EAM was performed using a 20-electrode catheter (2-6-2 mm spacing) and the Carto 3 system (Biosense Webster, Diamond Bar, CA). The segmented LGE image was registered to the EAM, and delayed activation (defined as 30 ms later than distal coronary sinus) was identified using ripple mapping. Results: The area of abnormal myocardium identified using LGE was 13.2±16.9 cm 2 (11.6±14.3% of total myocardium). In contrast, dense scar was limited at 1.53±3.83 cm 2 (1.52±4.31% of total myocardium). Delayed left atrial activation among

39 S526 Heart Rhythm, Vol. 15, No. 5, May Supplement ±477 sampled endocardial points corresponded to regional LGE with IIR>1.2. Conclusion: LGE with IIR > 1.2 appears to associate with delayed regional left atrial activation and may contribute to functional reentry as a substrate for AF. Lower thresholds for LGE detection appear to have less physiologic significance. AF voltage (AFV) and median AFV in rapid, stable and regular regions was not significantly different in 4/5 patients. The spatial distribution of rapid, stable and regular areas was markedly disparate between patients, with gradients from fast to slow AFCL (Fig 1B-C). Conclusion: ACL identifies regions with rapid, stable and regular AFCL in psaf and might be a useful tool to guide psaf ablation. The lack of spatial consistency of these sites between patients may underline the importance of individual ablation strategies for psaf ablation. B-PO NOVEL AF CYCLE LENGTH ALGORITHM IDENTIFIES RAPID REGULAR AND TEMPORALLY STABLE SOURCES IN PERSISTENT AF Szabolcs Z. Nagy, MD, Steve Kim, Ian Mann, MBBS, Valtino Afonso, Nick Linton, MBBS, Patrick Kasi, David C. Lefroy, Zachary I. Whinnett, BMBS, PhD, D. Wyn Davies, MD, FHRS, Fu Siong Ng, MBBS, PhD, Michael Koa-Wing, MBBS, Prapa Kanagaratnam, MD, PhD, Nicholas S. Peters, FHRS and Phang Lim, BCH, MB, MBChB. Imperial College Healthcare NHS Trust, London, United Kingdom, Abbott, Austin, TX, Imperial College London, London, United Kingdom, Abbott, Oakdale, MN, King s College London, London, United Kingdom, Abbott Laboratories, MN, Hammersmith Hospital, London, United Kingdom, Imperial College London, Rickmansworth, United Kingdom, London, United Kingdom, Imperial College London, Richmond, United Kingdom, Imperial College, London, United Kingdom, Imperial College Healthcare, St Mary s Hospital, Cardiology, London, United Kingdom, St Marys Hospital, Imperial College, Dept of Cardiology, London, England, United Kingdom Background: Rapid, regular, temporally-stable AF cycle length (AFCL) areas may have a role in persistent atrial fibrillation (psaf). Areas with >20s temporal AFCL stability have not been previously described. Objective: To identify areas with rapid, regular, temporallystable AFCL in psaf with a novel automated cycle length algorithm (ACL). Methods: Left atrial (LA) 3D electroanatomical mapping was performed in 5 patients during catheter ablation for psaf. Long AF segments (30-90s; LS) were recorded at stable locations with a 20-pole catheter. Consecutive 8s sub-segments were collected during each LS with a 1s sliding window and assessed for temporal AFCL variability, using ACL. ACL automatically excludes uninterpretable EGMs (Fig 1A). Rapid areas were defined as 15 th percentile of global AFCL for each patient, and stability as <10ms variation between first and last sub-segments. Results: Of 1862 LS locations (372/patient; range: ), 996 had continuous valid AFCL recordings of 20s (median 30s ([IQR:6]), these were used for further analyses. Global mean AFCL was significantly different between patients. Median global B-PO APPLICATION OF NOVEL ANALYSIS METHODS FOR CLINICAL INTRACARDIAC ELECTROGRAMS DURING ATRIAL FIBRILLATION Vasanth Ravikumar, MS, Elizabeth M. Annoni, Siva K. Mulpuru, BS, MB, MBBS, MD, FHRS, CCDS and Elena Talkachova. Department of Electrical Engineering, University of Minnesota, Minneapolis, MN, Minneapolis, MN, Mayo Clinic, Tucson, AZ Background: Catheter ablation has suboptimal success for patients with persistent AF. Recently, novel methods - Multiscale Frequency (MSF), Kurtosis (Kt), Shannon Entropy (SE), and Multiscale Entropy (MSE) - were proposed for accurate identification of the pivot points of the rotor, and validated using animal experiments. Objective: The aim of our study is to apply novel methods to human AF intracardiac electrograms (iegms), and to compare their prediction to identify the pivot point of the rotor with the traditional Dominant Frequency (DF) approach. Methods: Raw clinical iegms of the left atrium in a patient with AF were recorded using the CARTO 3 system. MSF, Kt, SE, MSE and DF values were calculated for all iegms, and corresponding patient-specific 3D maps were generated (see Fig.). Earth Mover s Distance (EMD) method was used to measure similarity between (1) all novel methods vs DF, (2) all novel methods among themselves. A threshold of 0.15 was set for EMD. Results: Recordings of iegms from 20 sites were considered. Overall, low similarity (<35% of spatial sites) was observed

40 Poster Session V S527 between DF and all the novel methods. However, all methods were well correlated among themselves, between 60% of sites (Kt vs MSF and SE) to 80% of sites (MSE vs SE). In addition, we observed that in 6 out of 20 sites the similarity between all novel methods was high, while their similarity with DF was extremely low. These 6 sites were identified to have incorrect identification of pivot point on the rotor. Conclusion: Novel methods for identification of the pivot point of the rotor using clinical iegms are highly correlated with DF in some, but not all sites, thus pointing out for inconsistency of traditional DF approach. is effective for many cases in returning the RA to sinus rhythm. Patient-specific modeling approaches have the potential to stratify patients prior to ablation by predicting if AF drivers are likely to be located in the LA or RA. B-PO PATIENT SPECIFIC SIMULATIONS PREDICT EFFICACY OF ABLATION OF INTERATRIAL CONNECTIONS FOR TREATMENT OF PERSISTENT ATRIAL FIBRILLATION Caroline Helen Roney, PhD, Steven E. Williams, MBChB, PhD, John Whitaker, Orod Razeghi, PhD, Iain Sim, MBBS, Louisa O Neill, MBBS, Rahul Mukherjee, MBBS, Remi Dubois, Hubert Cochet, MD, PhD, George J. Klein, MD, Edward J. Vigmond, PhD, Mark O Neill, PhD, FRCP and Steven A. Niederer, DPhil in Computer Science. King s College London, London, United Kingdom, London, United Kingdom, Hopital Cardiologique Haut Leveque - Université Bordeaux, Pessac, France, University Hospital, Cardiac Inv Unit, London, ON, Canada, University Bordeaux, Pessac, France Background: Treatments for persistent AF offer limited efficacy. One strategy aims to return the right atrium (RA) to sinus rhythm by ablating interatrial connections (IAC) to isolate the atria, but there is limited clinical data available to evaluate this approach. Objective: To evaluate IAC ablation using a simulation approach, and to predict patient-specific suitability for ablation of IAC to treat AF. Methods: Persistent AF was simulated in 12 patient-specific biatrial geometries, incorporating electrophysiological heterogeneity and fibers, with IAC at Bachmann s bundle, the coronary sinus and fossa ovalis. In addition, three models were tuned to LGE-MRI fibrosis and AF conduction velocity (CV) data. We simulated ablation of one, two or all three of the IAC, with or without pulmonary vein isolation (PVI) and characterized the resulting activity. Results: Ablating all IAC terminated RA arrhythmia in 75% of cases, independent of PVI (success Fig A; failure Fig B). RA termination occurred with longer RA cycle length (success: 230.4±25.7; failure: 210.0±7.4ms) and fewer RA rotors (0.97±0.76; 1.68±2.21), but independently of left atrial (LA) cycle length (190.6±5.9; 190.4±0.97ms). Tuning to patientspecific fibrosis and CV modified the response; RA arrhythmia terminated with high LA fibrosis density (Fig C), while LA AF terminated and RA sustained in cases with low RA CV (Fig D). Conclusion: This simulation study predicts that IAC ablation B-PO IDENTIFICATION OF CIRCUMFERENTIAL PULMONARY VEIN ISOLATION RESPONDER AMONG PATIENTS WITH PERSISTENT ATRIAL FIBRILLATION:THE VALUE OF SEQUENTIAL LOW-DOSE IBUTILIDE TEST Shunan He, MD, Ying Tian, Sr., Doctor, Liang Shi, Doctor, Yanjiang Wang, Xinchun Yang, M.D., Xingpeng Liu, MD and Lijun Zeng. Heart Center,Beijing Chao-yang Hospital,Capital Medical University, Beijing, China, Beijing Chaoyang Hospital, Beijing, China, Heart Center/Center for AF, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China, Beijiing Chaoyang Hospital, Capital Medical University, Beijing, China, Heart Center, Beijing Chao-yang Hospital, Capital Medical University, Beijing, China, Beijing Chao-yang Hospital, Bejijing, China Background: It is well established that the circumferential pulmonary vein isolation (CPVI) also works well in some patients with persistent atrial fibrillation (AF). However, the key question is how to identify these patients. Objective: In this study we investigated the value of a novel and simple drug test, namely the sequential low-dose ibutilide test, in identifying patients with persistent AF in whom the CPVI approach is effective as a sole therapy. Methods: In a prospective cohort of 185 consecutive patients with persistent AF, intravenous low-dose (0.004mg/kg) ibutilide was administered: 3 days before the procedure and after completion of CPVI during the procedure. If the same dose of ibutilide administered preprocedurally did not terminate AF, while administered intraprocedurally terminated AF, no further substrate modification was performed and a voltage map of the left atrium during sinus rhythm was created (CPVI responder group, n=60). The control group comprised of 379 patients with paroxysmal AF who underwent CPVI over the same period. In all patients, the endpoint of CPVI was confirmed by adenosine triphosphate provocation test. Results: In CPVI responder group, the mean continuous AF duration was 8.3±3.5 months and the baseline AF cycle length in the LA appendage was 153±18 ms. Left atrial low voltage (<0.5mV) areas were found in 6 (10%) patients. After a mean follow-up of 12.7 ± 3.5 months follow-up, 48 (80%) patients

41 S528 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 in the CPVI responder group and 313 (82.6%) patients in the control group were free from atrial tachyarrhythmias (P=NS) after the index procedure, respectively. Conclusion: The sequential low-dose ibutilide test is a simple method of identifying patients with persistent AF in whom the 1 year success rate of CPVI is similar to that in patients with paroxysmal AF. B-PO ARE THE USE OF IMAGING TECHNOLOGIES BEFORE THE PROCEDURE IMPACTFUL IN OUTCOME OF PULMONARY VEIN CRYOABLATION FOR RECURRENT AF? Giuseppe Arena, MD, Antonio Sagone, MD, PhD, Saverio Iacopino, Paolo Pieragnoli, MD, Roberto Verlato, Giulio Molon, Giulio Molon, Antonio Curnis, MD, Werner Rahue, Giuseppe Allocca, MD, Maurizio Lunati, Gaetano Senatore, MD and Claudio Tondo, MD, PhD. Nuovo Ospedale delle Apuane, Massa Carrara, Italy, Multimedica Holding S.p.A., Sesto San Giovanni, Italy, Arrhythmology Department GVM Care&Research, Lamezia Terme, Italy, University of Florence, Firenze, Italy, Ospedale Sacro Cuore, Negrar Verona, Italy, University of Brescia Medical School, Brescia, Italy, Ospedale Centrale, Bolzano, Italy, Osp. Civile Conegliano, Conegliano, Italy, Ospedale Niguarda, Italy, Ospedale Cirie, Cirie, Italy, Heart Rhythm Center, Monzino Cardiac Center, University of Milan, Milano, Italy Background: The usefulness of the imaging before the procedure on the long term success of cryoablation is still unknown. Objective: To evaluated the impact of imaging before Pulmonary Vein Cryoablation (PVC) on procedure time, acute complication and long term AF recurrence. Methods: From April 2012, 994 paroxysmal AF patients (70% male, 59 ± 11 years; mean left atrial diameter 41±6 mm) underwent index PVC. Data were collected prospectively in the framework of the 1STOP project, involving 36 Italian Cardiologic Centers. All patients were divided into two groups according to the availability and usage of imaging data (Computer tomography- CT- or Magnetic Resonance -MR) of PV anatomy during the procedure Results: Out of 994 patients, 469 were evaluated with CT or MR before the PVC (Imaging Group), while for 525 patients no imaging information were requested (No Imaging Group). The patient baseline characteristics are comparable between the 2 groups. The acute success rate were similar between the groups (98.6%), while the rate of acute procedural complications is significative different (7% in the Imaging Group vs 2.7% in the No Imaging Group). The difference is attributable on the numbers of transient diaphragmatic paralysis (19 patients in Imaging groups vs 1 patient in the No Imaging Group). The 12month freedom of AF recurrence probability was 76.5% in the imaging group as compared with 74.5% in the No imaging group (p=ns) as shown in fig 1. Conclusion: In our experience, in the 47% of procedures imaging data of left atrium were available to acquire adequate PV anatomical information for AF ablation. PVC seem to be effective regardless the availability of imaging data of PV anatomy. B-PO INCIDENCE OF FOCAL AND MACRO-REENTRANT ARRYTHMIAS DURING REPEAT PROCEDURES AFTER PAROXYSMAL ATRIAL FIBRILLATION ABLATION USING SECOND-GENERATION CRYOBALLOON WITH NO BONUS FREEZE APPLICATION Guillaume Viart, MD, Florence Vandevelde, MD, Clément Alarçon, MD, Arnaud Savouré, MD, Bénédicte Godin, MD, Nathanael Auquier, MD, Hélène Eltchaninoff, MD and Frédéric Anselme, MD, PhD. Rouen University Hospital, Department of Cardiology, FHU REMOD-VHF, F76000, Rouen, France, Rouen University Hospital, Department of Cardiology, FHU REMOD- VHF, Normandie Univ, UNIROUEN, INSERM U1096, F76000, Rouen, France Background: The second-generation cryoballoon (CB2) is effective in achieving pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF). Few data have been reported regarding the mechanism of atrial arrhythmias leading to repeat procedures after CB2-based ablations. Objective: To describe clinical arrythmias leading to repeat procedures after PVI using CB2. Methods: We analyzed data from all consecutive patients requiring repeat procedures for symptomatic left atrial arrhythmias after PVI using the 28 mm CB2 with no bonus freeze application. All repeat ablations were performed using a 3D mapping system. A lasso catheter was used to check pulmonary veins (PV) isolation and map the clinical arrhythmia. Ablation was performed using radiofrequency energy. Results: From January 2014 to December 2016, 31/270 patients (11.5%), mean age 56±10 years, had repeat procedures for paroxysmal AF (24/31; 77.4%), persistent AF (1/31; 3.2%), atypical flutter (4/31; 12.9%) or left atrial tachycardia (2/31; 6.4%) after 8±8 months following PVI. Four patients required 2 repeat procedures. Among those 31 patients, 25 (80.6%) had at least one reconnected PV, but only 46/124 PVs (37.1%) were reconnected. All PVs were re-isolated using radiofrequency. Focal arrythmias were targeted in 12/31 (38.7%) patients, whereas left reentrant arryhthmias were found in 4/31(12.9%) patients. Cavo-tricuspid isthmus ablation was performed in 7/31 (22.6%) patients after induction of typical atrial flutter. The superior vena cava was isolated in 5/31 (16.1%) patients. Only 17/31 patients (54.8%) had PVI alone during those redo procedures using radiofrequency. After a 4 months follow-up, 19/31 (61.3%) patients were free from any symptom or recorded

42 Poster Session V S529 AF, reaching an overall 95.6% success rate (258/270) after 2 or 3 procedures. Conclusion: The need of repeat procedures is rather low after PVI using CB2 with no bonus freeze application. Atrial arrythmias recurrence can be related not only to PV reconnection, but also to focal or reentrant atrial arrythmias. These results support the use of 3D-mapping-guided radiofrequency ablation for repeat procedures after cryoballoon ablation. B-PO CRYOBALLOON PULMONARY VEIN ISOLATION IS ASSOCIATED WITH LOWER RATES OF DORMANT CONDUCTION AND ATRIAL FIBRILLATION RECURRENCE COMPARED WITH RADIOFREQUENCY ABLATION Rajat Goyal, MD, Steven M. Markowitz, MD, FHRS, Jim W. Cheung, MD, FHRS, George Thomas, MD, James E. Ip, Bruce B. Lerman, MD, FHRS, CCDS and Christopher F. Liu, MD, FHRS. NYP/Weill Cornell Medical Center, New York, NY, New York Presbyterian Hospital and Cornell Medical Center, New York, NY, Weill Cornell Medical College, New York, NY, Weill Cornell Medical College - Cardiology, New York, NY, Weill Cornell Medical Center, Dept of Cardiothoracic Surgery, Cornell Univ Medical Center - The New York Hospital, New York, NY Background: Cryoballoon and focal radiofrequency (RF) are established energy sources for pulmonary vein (PV) isolation. Dormant PV conduction with adenosine injection is associated with higher risk of AF recurrence. Objective: We compared the incidence of dormant PV conduction and AF recurrence in contemporaneous cryoballoon and RF cases. Methods: We retrospectively evaluated 81 pts (consecutive 41 cryo and 40 RF cases) who underwent ablation for paroxysmal AF. A single 28mm second generation cryoballoon was used in all cryo cases. A contact force-enabled RF catheter (Carto SmartTouch) was used in all RF cases. After PV isolation and 30 minute waiting period, adenosine 12 mg was given to assess for dormant conduction in each PV. All PVs were isolated; additional ablation was given for dormant PV conduction. AF/AT recurrence was based on symptoms and serial event monitoring at 3 month intervals in the first year. Results: Cryo and RF patients (pts) showed no significant difference in age, sex, HTN, BMI, OSA, or LVEF. Mean left atrial diameter was 3.8±0.7 cm for cryo pts vs 4.1±0.7 cm for RF pts (P=0.04). After isolation, dissociated potentials were noted in 12% of cryo PVs vs 23% of RF PVs (P=0.008), in 27% of cryo vs 48% of RF pts (P=0.06). With adenosine testing, dormant PV conduction was seen in 5% of cryo vs 20% of RF pts (P=0.05). At 1 year follow-up, 90% of cryo cases remained free of AF and AT vs 67% of RF cases (P=0.01). Conclusion: PV isolation with second generation cryoballoon showed lower incidence of adenosine-driven dormant conduction and higher rate of freedom from AF/AT at 1 year follow-up. There was also a significantly lower incidence of dissociated PV potentials after cryoballoon isolation. B-PO ATRIAL ABLATION LINE DURABILITY AND CONTIGUITY: EVALUATION OF A NOVEL RADIOFREQUENCY ABLATION SYSTEM IN A SWINE ATRIAL LINEAR LESION MODEL Elad Anter, MD, Michael Barkagan, MD, Eran Leshem, MD, MHA, Monica Sanchez, Fernando M. Contreras Valdes, MD and Alfred E. Buxton, MD. BIDMC, Cardiology, Boston, MA, BIDMC, Cardiology, Brighton, MA, Beth Israel Deaconess Medical Center, Brookline, MA, Beth Israel Deaconess Medical Center, Cardiovascular Medicine, Waltham, MA, Beth Israel Deaconess Medical Center, Boston, MA Background: RF ablation is associated with a relatively long application duration and inconsistent tissue injury, often resulting in noncontiguous lines and presence of ablation gaps. Objective: Evaluate a novel RF ablation technology for producing contiguous and durable atrial lines. Methods: This ablation system (Affera, Inc.) includes a catheter with an expandable irrigated-tip containing 9 thermocouples and minielectrodes (Sphere 9 ). RF is delivered from a conductive mesh scaffold in temperature-controlled mode using a proprietary generator. In 5 swine, alternating posterior and lateral right atrial (RA) lines were performed with Sphere 9 and conventional 3.5mm irrigated catheter. Lower RF settings were used for posterior lines (T80 o C/5sec and 25W/20sec) and higher RF settings for lateral lines (T80 o C/7sec and 30W/20sec). Following 3 weeks of survival period, line continuity was evaluated by voltage mapping using the novel system, electrogram characteristics, and pathological analysis. Results: Line integrity after 3 weeks by voltage mapping was higher with Sphere 9 [5/5 (100%) vs 1/5 (20%)]. Electrograms with double-potentials were present in intact lines but absent in noncontiguous lines. Pathological analysis demonstrated contiguous and homogenous lines with Sphere 9 compared with inconsistent and discontinuous conventional ablation (Figure). Sphere 9 lines were wider [posterior: 10.7±3.4 vs 4±2.3mm (p<0.0001); lateral: 12.4±2.3mm vs 3.7±2.8mm (p<0.0001)]. Conclusion: In this swine model, this novel RF ablation system produces atrial lines that are more contiguous and durable compared to conventional RF ablation.

43 S530 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO PRESSURE-GUIDED CRYOBALLOON ISOLATION OF THE PULMONARY VEINS DECREASE THE RISK OF SILENT STROKES IN PERIOPERATIVE PERIOD Kazuya Yamao, MD, Hitoshi Hachiya, MD, PhD, Miyako Igarashi, Shigeki Kusa, MD, PhD, Takatsugu Kajiyama, MD, Akinori Sugano, MD, Masao Yamaguchi, MD, Masahiro Hada, MD, Yoshinori Kanno, MD and Yoshito Iesaka, MD, PhD. Tuchiura Kyodo General Hospital, Tuchiura, Japan Background: Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV occlusion is typically assessed by contrast injection in cryoballoon ablation (CBA). However, a repetitive contrast injection might be increased the risk of silent strokes. Objective: We assessed the event rate of silent strokes and the total microembolic signal (MES) burden in transcranial doppler (TCD) between Pressure-Guided Group and Conventional Treatment group. Methods: Among total 201 paroxysmal AF patients who underwent PVI using exclusively 28-mm second-generation cryoballoon, 36 patients (18%) underwent pressure-guided CBA procedure using the change of PV wedge pressure at the tip of the cryoballoon (Pressure Group). The remaining 165 patients (82%) conducted a conventional CBA procedure using some contrast injections. TCD was used to detect the total MES burden during CBA procedure. Cerebral magnetic resonance imaging was conducted before and after CBA procedure for assessing silent strokes. Results: The total MES burden was higher in Conventional group than Pressure group (548 ± 327 vs. 317 ± 149; p< 0.01). Event rate of silent strokes was also higher in conventional group than Pressure group (42/165 vs 2/36; p=0.009). The rate of touch-up ablation in CBA (15/165 vs. 4/36, p=0.70) and major complication except silent strokes were comparable between Pressure- and Conventional-groups. Conclusion: CBA with direct pressure monitoring be useful to decrease the risk of silent strokes. Background: Ablation with higher power could facilitate shortening of ablation time and reduce the procedural time while preserving efficacy. Objective: To investigate the safety and capability of lesion creation using a short duration and high power ablation (SDHP) catheter equipped with 6 surface thermocouples (TCs) temperature monitoring. Methods: Four dogs underwent pulmonary vein isolation (PVI) using the SDHP catheter or standard irrigated-tip catheter (SC). Ablation was performed using settings of 90W, RF time of 4sec and 15mL/min irrigation for SDHP and 30-35W, 30sec, and 30 ml/min for SC. Temperature limit was 65 C in both groups. Catheter contact force (CF) of 10-20g was defined as normal CF and CF of > 20g as firm CF. The tissue temperature was monitored during ablation using TCs that were implanted at the LA-PV junction, phrenic nerve, and luminal esophagus. Gross and microscopic pathology was examined. Results: In total, 152 RF applications (SDHP n=135, SC n=17) were investigated. PVI was achieved in 7/8 (88%) PVs and transmural PV lesion circumferentiality was 97±7% with shorter RF time in SDHP compared with SC group (64±24 vs. 255±21sec/PV, p<0.001). The figure shows results of the tissue temperature investigation during ablation. The distance margin to keep tissue temperature <42 C was 4.2 mm in SDHP (sensitivity 0.92, specificity 0.91) and 6.6 mm in SC group (sensitivity 0.94, specificity 0.94). There were no complications or collateral lesion in either group. Conclusion: This novel SDHP catheter showed potential for creating circumferential, transmural lesions while decreasing required RF time with overall equivalent safety as conventional catheter ablation. B-PO SPATIAL THERMODYNAMICS OF PULMONARY VEIN ISOLATION USING A NOVEL SHORT DURATION AND HIGH POWER ABLATION CATHETER FOR TEMPERATURE- LIMITED ABLATION Atsushi Suzuki, MD, PhD, Songyun Wang, II, PhD, H. Immo Lehmann, MD, Maryam Rettmann, Kay D. Parker, CVT and Douglas L. Packer, MD, FHRS. Mayo Clinic/St. Marys Hospital, Rochester, MN, Renmin Hospital of Wuhan University, Wuhan, China, Mayo Clinic, Pittsburgh, PA, Mayo Clinic, Rochester, MN, Mayo Clinic - St. Mary s Hospital, Rochester, MN B-PO FEASIBILITY AND SAFETY OF SAME-DAY DISCHARGE FOLLOWING CATHETER ABLATION FOR ATRIAL FIBRILLATION Stefano Bartoletti, Mandeep Mann, Akanksha Gupta, Abdul Khan, Ankita Sahni, Moutaz El-Kadri, Julian Hobbs, Simon Modi, Johan Waktare, Saagar Mahida, Mark Hall, Richard Snowdon, Derick Todd and Dhiraj Gupta. Liverpool Heart And Chest Hospital, Liverpool, United Kingdom

44 Poster Session V S531 Background: AF ablation traditionally involves at least an overnight hospital stay. Objective: We hypothesized that ultrasound-guided venous access and a streamlined peri-ablation anticoagulation strategy would allow early mobilization and facilitate same-day discharge. Methods: Our AF ablation policy includes mandatory use of vascular ultrasound, continued warfarin pre-procedure, avoiding heparin bridging, and protamine use prior to sheath removal. Non-vitamin K oral anticoagulants (NOACs) are omitted on the morning of ablation. From 2014, we started offering same-day discharge to selected patients who underwent uncomplicated AF ablation on the morning lists, with no routine post-ablation echocardiogram. Patients were discharged between 19:00 and 20:00 hours and offered access to a dedicated nurse helpline. Results: From April 2014 to March 2017, 169/811 (20.8%) AF ablation cases performed on the morning lists were discharged on the same day. Of these, 1 had transient right phrenic nerve palsy which resolved before discharge, and 5 (2.9%) cases experienced minor problems which did not preclude sameday discharge; 4 (2.3%) patients needed re-hospitalization post-discharge: 2 for pericarditic chest pain and 2 for nausea/ vomiting. Compared to 642 cases who stayed overnight, daycase procedures were shorter, more likely to be redos and to be performed under sedation rather than general anesthesia (Table). Conclusion: A streamlined protocol (including ultrasoundguided access) allows for safe day-case AF ablation. Its wider adoption can potentially reduce health-care costs while improving patient experience. surrogate of EAR, with high DFs indicating a significant EAR. Objective: We hypothesized that bi-atrial EGM DFs of patients (pts) in whom CA failed 1) to terminate paf into sinus rhythm (SR) or atrial tachycardia, and 2) to maintain SR during follow-up (FU) is higher than that of pts with a successful procedure. Methods: In 40 consecutive pts (61±8 y, sustained AF 19±11 m), pulmonary vein isolation and left atrium (LA) ablation were performed until paf termination or cardioversion. 20-sec EGMs were sequentially recorded before ablation at 13 LA sites, and at the right atrial appendage (RAA) synchronously to each LA site. DF was defined as the highest peak within the [3-15]Hz EGM spectrum. Recurrence (Rec) during FU was defined as any atrial arrhythmia > 30 sec. Results: paf was terminated within the LA in 70% (28/40, LT) of the pts, while 30% (12/40, NLT) were not. Over a mean FU of 34±14 months, all NLT pts had a Rec, while LT pts presented a Rec in 71% (20/28, LT_Rec) and remained in SR in 29% (8/28, LT_SR). Panel A of the figure shows a gradual decrease in mean LA, LAA and RAA DFs with the highest values in NLT pts, intermediate ones in LT-_Rec pts and the lowest values in LT_ SR pts. The left-to-right DF gradient calculated as the difference between LAA and RAA DFs was negative in NLT pts but positive in LT pts (Fig. B). Conclusion: Patients with an unsuccessful procedure and AF recurrence at follow-up present high bi-atrial DFs indicative of a severe atrial remodeling. B-PO B-PO RECURRENCE AFTER ABLATION OF PERSISTENT ATRIAL FIBRILLATION OCCURS IN PATIENTS WITH SEVERE BI- ATRIAL ELECTRO-ANATOMICAL REMODELING Adrian Luca, PhD, Andrea Buttu, PhD, Jean-Marc Vesin, PhD, Alain Pithon, Mathieu Le Bloa, MD, Laurence Bisch, MD, Patrizio Pascale, MD, Laurent Roten, MD, Christian Sticherling, MD and Etienne Pruvot, MD. Lausanne University Hospital, Lausanne, Switzerland, Ecole Polythechnique Fédérale de Lausanne, Lausanne, Switzerland, Inselspital, Bern, Switzerland, Univ Hospital Basel, Basel, Switzerland Background: Persistent atrial fibrillation (paf) involves some level of electroanatomical remodeling (EAR) whose severity affects the success rate of catheter ablation (CA). The dominant frequency (DF) of intracardiac electrograms (EGM) is a INCREASE OF C REACTIVE PROTEIN IS ASSOCIATED WITH EARLY RECURRENCE OF ATRIAL FIBRILLATION AFTER CRYOBALLOON ABLATION Kenichi Yokoyama, MD, Michifumi Tokuda, MD, Hidenori Sato, Eri Okajima, Hidetsugu Ikewaki, Hirotsuna Oseto, Ryota Isogai, Kenichi Tokutake, Ryohsuke Narui, MD, Mika Kato, M.D., Shinichi Tanigawa, Seigo Yamashita, MD, Seiichiro Matsuo, MD and Teiichi Yamane, MD, PhD, FHRS. Jikei University School of Medicine, Tokyo, Japan, The Jikei University School of Medicine, Yokohama, Japan, The Jikei University School of Medicine, Tokyo, Japan, Jikei Univ School Of Med, Japan, Jikei Univ School of Medicine, Tokyo, Japan Background: Early recurrence of atrial fibrillation (ERAF) sometimes occurred after cryoballoon ablation. ERAF (<90days) following radiofrequency catheter ablation has been shown to be associated with inflammatory response by thermal energy. However, its relationship with the clinical outcomes of

45 S532 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 cryoballoon ablation has not been determined. Objective: The purpose of this study is to assess the relationship between ERAF and increase of inflammatory biomarkers after cryoballoon ablation. Methods: A total of 221 patients (884 PVs) with paroxysmal AF who underwent the initial cryoballoon ablation were included. Patients were divided into two groups according to the presence/ absence of ERAF. Post-procedural increase of inflammatory biomarkers (C reactive protein (CRP), white blood cell (WBC), creatinine kinase (CK) and CK-MB) was compared between two groups. Biomarkers were evaluated on the day before and one day after the cryoballoon ablation procedure. Results: All PVs were successfully isolated. Touch-up ablation was required in 8.7% of PVs. ERAF was observed in 35 (16%) patients after cryoballoon ablation. While increase rate of CRP value (post-procedure/baseline) was significantly higher in patients with ERAF than those without (33.9±27.7 vs. 23.5±18, p=0.005), other inflammatory biomarkers were not associated with ppearance of ERAF. (WBC: 9.9± /μl vs. 9.7± / μl, p=0.6, CK: 410±16U/l vs. 444±159U/l, p=0.25, CK-MB: 39.8±13.5U/l vs. 42.3±17U/l, p=0.4, respectively ) However, elevation of inflammatory markers did not related to true AF recurrence (CRP: 27.8±17.7 vs. 25.9±18.5, p=0.59 WBC: 9.3± /μl, vs. 9.8± /μl, p=0.3, CK: 404±210 U/l vs. 444±150 U/l, p=0.2, CK-MB: 36.3±14.1 U/l vs. 42±16.7 U/l, p=0.04). Conclusion: Elevation of CRP was associated with the ERAF following cryoballoon ablation. Close relationship between CRP and ERAF suggests that ERAF is associated with postprocedural inflammation after cryoballoon ablation. B-PO RELATIONSHIP AMONG VERY EARLY, EARLY AND TRUE RECURRENCE OF ATRIAL FIBRILLATION AFTER CRYOBALLOON ABLATION Kenichi Yokoyama, MD, Michifumi Tokuda, MD, Ryota Isogai, Kenichi Tokutake, Ryohsuke Narui, MD, Mika Kato, M.D., Shinichi Tanigawa, Seigo Yamashita, MD, Seiichiro Matsuo, MD and Teiichi Yamane. Jikei University School of Medicine, Tokyo, Japan, The Jikei University School of Medicine, Yokohama, Japan, The Jikei University School of Medicine, Tokyo, Japan, Jikei Univ School Of Med, Japan, Jikei Univ School of Medicine, Tokyo, Japan Background: Previous studies reported that early recurrence of atrial fibrillation (ERAF) following radiofrequency catheter ablation (90 days) was associated with true AF recurrence. Since ERAF is also occurred after cryoballoon ablation, its clinical significance has not been fully determined. Objective: The purpose of this study is to assess the relationship between ERAF and true AF recurrence after cryoballoon ablation. Methods: Consecutive 221 patients (884 PVs) with paroxysmal AF who underwent the initial cryoballoon ablation were included. AF recurrence was classified into 3 types according to the phase of recurrence (very early recurrence of AF (VERAF); 0-3 days, ERAF; 4-90 days, true AF recurrence; 91- days). Recurrence of AF was evaluated based on continuous monitoring during admission, and ECG recordings and 24-hour Holter monitoring during a periodical follow-up in outpatient clinic. Results: All PVs were successfully isolated. Touch-up ablation was required in 8.7% of PVs. ERAF was observed in 35 (16%) patients after cryoballoon ablation. There was no significant characteristic difference between two groups. During 23±10 months of follow up, VERAF, ERAF and true AF recurrence occurred in 31 (14%), 11 (5%) and 31 (14%) patients, respectively. In 23 (74%) patients with VERAF, ERAF was not observed. VERAF and ERAF were more frequently observed in the patients with true AF recurrence than those without (32% vs. 11%, p=0.004 and 22% vs. 2%, P<0.0001, respectively). In multivariate analysis, ERAF was associated with true AF recurrence (OR 4.9, 95% CI , p=0.02), while VERAF was not associated (OR 0.3, 95% CI , p=0.58). Conclusion: In multivariate analysis, ERAF rather than VERAF was associated with true AF recurrence. VERAF after cryoballoon ablation might indicate transient inflammatory response. B-PO MECHANISMS OF RECURRENT ATRIAL ARRHYTHMIAS FOLLOWING FIRM GUIDED ABLATIONS Chris Latanich, MD, Jamie Voss, MBChB, Eyad Alhaj, MD, Christopher A. Henry, Michael Hushion, Joseph A. Cytron, MD, Smit C. Vasaiwala, MD, Alexander Green, MD, Brian J. Vetter, MSBME, Peter A. Santucci, MD, FHRS and David J. Wilber, MD, FHRS, CCDS. Loyola University Medical Center, Maywood, IL, Loyola University Medical Center, Chicago, IL, Loyola Medical Center, Maywood, IL, Loyola Univ Medical Center, Chicago, IL, Loyola Univ Medical Center, Dept of Cardiology, Maywood, IL, Loyola, Maywood, IL, Loyola Univ Chicago, Cardiology, Maywood, IL, Loyola Univ Medical Center, Cardiovascular Institute, Maywood, IL Background: The mechanisms of recurrent atrial arrhythmias (AA) following Focal Impulse and Rotor Modulation (FIRM) guided atrial fibrillation (AF) ablation remains incompletely characterized. Objective: This study aims to better discern the nature of recurrent AAs among pts undergoing repeat ablation following an initial FIRM guided procedure, as well as the potential role of prior FIRM ablation in the genesis of subsequent AA. Methods: Of 251 consecutive pts undergoing first time FIRM guided AF ablation, 35 (14%) underwent a redo procedure at a median of 12.1 (IQR ) mo following initial ablation. The mean age was 62 ± 9 yrs and mean CHADs2VASc score 2.5 ± 1.6. Recurrent AA before redo ablation included AF only in 43%, atrial tachycardia (AT) only in 14%, and both in 43%. The mechanisms of ATs were characterized by electroanatomical mapping and entrainment. Pts with spontaneous or induced AF underwent repeat FIRM mapping. Finally, the location of focal ATs or critical isthmuses for macroreentrant AT, as well as FIRM sites identified at the time of repeat ablation were compared to the electroanatomic maps of previously ablated FIRM sites. Colocalization within 1 cm was considered similar. Results: At the time of initial FIRM guided ablation, there were 4.5 ± 3.0 FIRM sites ablated per patient (n = 35). During the redo procedure, there were 40 ATs identified in 20 patients with 26 macroreentrant ATs (cavotricuspid 14, mitral 7, roof 5), and 14 focal ATs. Previously ablated FIRM sites were located within the critical isthmus of 4/26 (15%) macroreentrant ATs, and only 4/14 (29%) focal ATs arose from sites colocalized with previous FIRM ablation. Repeat FIRM ablation was performed in 14 pts. There were 3.2 ± 2.2 FIRM sites/pt. Only 7/45 (16%) redo FIRM sites were similar to previously ablated FIRM sites, the remainder were at new locations. Conclusion: The majority of ATs among pts undergoing a repeat procedure after prior FIRM guided ablation appeared to have little relationship to previous FIRM ablation sites, suggesting proarrhythmia may not be the primary cause of recurrent AA. A large majority of FIRM sites identified at redo procedures were remote from previously ablated FIRM sites.

46 Poster Session V S533 B-PO TREATMENT AND PROGNOSIS OF TACHYCARDIA- BRADYCARDIA SYNDROME DURING THE BLANK PERIOD AFTER ATRIAL FIBRILLATION ABLATION Dong Chang, MD, PhD. First Affiliated Hospital of Dalian Medical University, Dalian, China Background: During blank perioed after catheter ablation of atrial fibrillation (AF), some patients have recureent atrial tachyarrhythmias with long pause after termination. It is called blank tachybradycardia syndrome (BTBS). However, there is no data reported about the BTBS. Objective: The present study was aimed to address mechanism, treatment and prognosis of BTBS. Methods: The present study checked up the patients with AF ablation in our hospital from January 2003 to June We reviewed the rhythm control of patients in blank period. Results: 30 patients had BTBS with the incidence of 1.1% (group A). Other 30 recurrent AF patients without long pause entered into group B. Another 30 patients without recurrent AF were enrolled as group C. HRV of group C was significantly lower than groups A and B. The patients without early recurrence of HRV after radiofrequency ablation were significantly lower than those with recurrence.in group A, 12 patients underwent re-ablation (8 cases were ablated during the blank period and 4 cases were ablated after the blank period). 3 patients underwent permanent pacemaker implantation. The other 15 patients refused re-ablation or implant of pacemaker. Following up 36.9±23.9 months,10/12 patients maintained sinus rhythm after the second ablation and 2 patients still had recurrent AF without long pause. 12/15 patients without pacemaker and re-ablation had no recurrence of AF, and 3/15 patients still had recurrent AF without long pause. 3 patients accepted pacemaker had recurrent AF. Conclusion: BTBS was not rare. Most patients of BTBS do not require second ablation or pacemaker after the blank period with favorable prognosis. B-PO CONTINUATION OF ANTI-ARRHYTHMIC DRUGS THROUGH THE PERIPROCEDURAL PERIOD OF CATHETER ABLATION IN PATIENTS WITH PERSISTENT ATRIAL FIBRILLATION Ryohsuke Narui, MD, Seiichiro Matsuo, MD, Hirotsugu Ikewaki, Eri Okajima, Hidenori Sato, Hirotsuna Oseto, Ryota Isogai, Kenichi Tokutake, Kenichi Yokoyama, Mika Hioki, M.D., Shinichi Tanigawa, Michifumi Tokuda, MD, Seigo Yamashita, MD, Keiichi Inada, Kenichi Sugimoto, MD, Michihiro Yoshimura and Teiichi Yamane, MD, PhD, FHRS. The Jikei University School of Medicine, Tokyo, Japan, Jikei Univ School Of Med, Japan, Jikei University School of Medicine, Tokyo, Japan, The Jikei University School of Medicine, Yokohama, Japan, Jikei University School Of Med, Tokyo, Japan, Jikei Hospital, Tokyo, Japan, Jikei Univ School of Medicine, Tokyo, Japan Background: Catheter ablation for atrial fibrillation (AF) is basically performed with cessation of antiarrhythmic drugs (AADs) which could affect the arrhythmogenic activity and clinical outcome. Objective: We investigated the impact of AADs on electrophysiological properties and clinical outcome of catheter ablation in persistent AF patients. Methods: This study consisted of 121 persistent AF patients with AADs (bepridil:113, amiodaron:4 and others:4 patients) who underwent the initial ablation. The patients were divided into the following two groups according to continuation or discontinuation of AADs in the perioperative period: Group C: 66 patients with continuation of AADs) and Group D: 55 patients with discontinuation of AADs. Results: AF rhythm at the start of procedure was more frequently observed in Group D than Group C (66.7% vs. 38.2%, P=0.002). A spontaneous dissociated pulmonary vein (PV) activity after PV isolation and the incidence of non-pv triggers were more frequently seen in Group D compared to group C (17.7% vs. 10.6%, P=0.03 and 25.8% vs. 9.1% P=0.02, respectively). Meanwhile incidence of adenosine-induced dormant PV conduction did not differ between the two groups (8.8% vs. 6.2%, P=0.32, in Groups D and C, respectively). Although the incidence of early recurrence of AF (ERAF) which occurred within 3 days after the procedure did not differ between 2 groups (25.5% (14/55) vs. 30.3% (20/66), in Group D and C, P=0.56), ERAF requiring direct current cardioversion (DCC) was more frequently observed in Group D compared to Group C (18.2% (12/66) vs. 5.4% (3/55), P=0.03). The final outcome of AF ablation following the initial procedure was similar between the two groups (25.8% vs. 27.3%, in Groups D and C, P=0.42). Conclusion: Although continuation of AADs reduced the incidence of a dissociated PV activity after PV isolation, non-pv triggers during ablation procedure and ERAF requiring DCC which occurred within 3 days after the procedure, it did not affect the clinical outcome following catheter ablation in patients with PrAF. B-PO SEVERITY OF CHRONIC KIDNEY DISEASE IS ASSOCIATED WITH THE PRESENCE OF LEFT ATRIAL LOW-VOLTAGE AREAS Yasuhiro Matsuda, MD, Masaharu Masuda, MD, PhD, Mitsutoshi Asai, MD, Osamu Iida, MD, Shin Okamoto, MD, Takayuki Ishihara, MD, Kiyonori Nanto, MD, Takashi Kanda, MD, Takuya Tsujimura, MD, Shota Okuno, MD, Takuya Ohashi, MD, Hiroyuki Kawai, MD, Aki Tsuji, MD, Yosuke Hata, MD, Hiroyuki Uematsu, MD, Yuki Sato, MD and Toshiaki Mano, MD, PhD. Kansai Rosai Hospital, Amagasaki, Japan Background: The presence of low-voltage areas (LVA) has been shown to correlate with atrial fibrillation recurrence after catheter ablation. A previous study demonstrated patients with chronic kidney disease (CKD) increased the rate of recurrence of atrial fibrillation. Objective: The purpose of this study was to elucidate the association between severity of CKD and LVA presence. Methods: One hundred eighty three patients who underwent the first procedure of catheter ablation were included (age, 67 ± 9 years old; male, 134 (73%) patients; persistent atrial fibrillation, 82 (45%) patients). LVA were defined as sites of the left atrial electrogram amplitude <0.5mV. Blood sample of creatinine and cystatin C before the procedure were obtained. Results: Of 183 patients, LVA existed in 76 (42%) patients. Patients with LVA demonstrated lower estimated glomerular filtration rate (egfr) calculated by creatinine (P= 0.01) and cystatin C (P <0.001). Receiver operating characteristic curve analysis revealed that egfr calculated by cystatin C was a good predictor of LVA presence (area under the curve, 0.669). The optimal cut-off value of egfr calculated by cystatin C was 71.5ml/min/1.73m 2 corresponded to 79.4% sensitivity, 50.0% specificity and 67.2% predictive accuracy. LVA existed more frequently in patients with more severe categories of CKD (Figure). Independent predictors of LVA presence were egfr<71.5ml/min/1.73m 2 (odds ratio (OR) 2.8, 95% confidence interval (CI) , P =0.012) and high age (OR 1.05, 95% CI , P =0.028). Conclusion: The prevalence of LVA increases depending on

47 S534 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 the severity of CKD in patients with atrial fibrillation undergoing catheter ablation. B-PO VALIDATION OF THE LESION SIZE INDEX IN AN IN VITRO PORCINE HEART: IMPLICATION OF A DURABLE PULMONARY VEIN ISOLATION Masaru Arai, MD, Yasuo Okumura, MD, PhD, Koichi Nagashima, MD, PhD, Kazuki Iso, MD, Keiko Takahashi, M.D., Ryuta Watanabe, MD, Yuji Wakamatsu, MD, Sayaka Kurokawa, Kimie Ohkubo, MD, Toshiko Nakai, MD and Ichiro Watanabe, MD, PhD. Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan, Nihon University School of Medicine, Tokyo, Japan, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan, Nihon University, Tokyo, Japan, Tokyo, Nihon University School of Medicine, Tokyo, Japan Background: The contact force (CF), power and radiofrequency (RF) time have been shown to be robust determinants of lesion durability during pulmonary vein isolation (PVI) of atrial fibrillation (AF). Recently, the Lesion Size Index (LSI) has been developed for a novel marker of the lesion size that incorporates the CF, RF current and RF time, and thus, predicts the lesion size during ablation. Objective: To investigate whether RF ablation guided by the LSI could predict a real lesion formation, and is applicable for a clinical PVI. Methods: 1) Two excised pig ventricular walls underwent ablation guided by the LSI. The relationship between 3 LSI values (4.5, 5 and 5.5) at settings of the CF of 10, 15 and 20 grams and an individual lesion formation was evaluated during irrigated-tip ablation (flow 17 ml/sec) at 30 watts. 2) In 47 patients, the PV antra wall thickness was measured from CT images. Results: We created 45 ablation lesions (n=5 for each protocol). When a 10 g CF was applied, the lesion width and depth increased gradually from an LSI 4.5 to 5.0 to 5.5 (P=0.0020). When 15 g and 20g CFs were applied, there were no differences in the lesion width and depth between the LSI 4.5, 5.0 and 5.5, but all lesions were at least 3 mm in depth (Figure). The PV antra thickness was 1.2±0.2 mm at PV carina sites and 1.0±0.2 mm at other PV sites, respectively, which were significantly thinner than the lesion depth obtained from the LSI-based ablation in this study (P<0.001). Conclusion: The LSI was highly associated with the lesion size if a CF of 10g was applied, but not for a CF of 15 g. Significant deeper lesions guided by the LSI than the human PV antra wall thickness suggested that an LSI of would be suitable for a durable PVI. B-PO CATHETER ABLATION IN HIV-POSITIVE PATIENTS WITH ATRIAL FIBRILLATION Chintan G. Trivedi, MD, MPH, FHRS, Sanghamitra Mohanty, MD, FHRS, Carola Gianni, MD, PhD, Domenico Della Rocca, J. David Burkhardt, MD, PhD, Javier E. Sanchez, MD, Patrick M. Hranitzky, MD, FHRS, G. Joseph Gallinghouse, MD, FHRS, Amin Al-Ahmad, MD, FHRS, CCDS, Rodney P. Horton, MD, FHRS, Richard H. Hongo, MD, FHRS, Salwa H. Beheiry, Luigi Di Biase, MD, PhD, FHRS and Andrea Natale, MD, FHRS. Texas Cardiac Arrhythmia Institute, Electrophysiology, Austin, TX, St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Institute, Austin, TX, TCAI, Austin, Austin, TX, Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, Texas Cardiac Arrythmia Institute, Austin, TX, Texas Cardiac Arrhythmia, Austin, TX, Texas Cardiac Arrhythmia Research, Austin, TX, California Pacific Medical Center, San Francisco, CA, California Pacific Medical Center, Albert Einstein College of Medicine at Montefiore Hospital, New York, NY Background: Earlier studies have shown a clear association between severity of HIV infection and incident atrial fibrillation (AF). However, there is no published data delineating the electrophysiological characteristics of AF patients in this highly selective population. Objective: We present the procedural parameters and long-term outcome of catheter ablation in HIV positive AF patients. Methods: This prospective analysis included 23 consecutive HIV positive individuals undergoing their first AF ablation at our centers. All received PVI + isolation of posterior wall and superior vena cava. Non-PV triggers were identified with high-dose isoproterenol-challenge (up to 30 µg/min for min). These were defined as ectopic triggers originating from sites other than pulmonary veins such as interatrial septum (IAS), mitral valve annulus, left atrial appendage (LAA), crista terminalis (CT) and coronary sinus (CS). Patients were monitored for arrhythmia at quarterly office visits, ECGs, 7-day holter monitoring and event recorders. Results: The study population was younger (48.7±11years), mostly men (18, 78%), 10 (43.5%) had paroxysmal AF and 13 (56.5%) had persistent AF. During the procedure, non-pv triggers were detected in 13 (56.5%) cases. These triggers were mostly mapped to LAA (7, 53.8%) and CS (8, 61.5%). Besides, ectopic beats were seen originating from IAS (3, 23%) and CT (4, 30.7%). Electrical isolation of LAA and CS and focal ablation of non-pv triggers from other sites were successfully performed. By the end of 5-years of follow-up, all 23 patients had

48 Poster Session V S535 experienced recurrence; 21 of 23 (91.3%) received repeat ablation. Pulmonary vein reconnection was detected in 3 (14%) patients. Isoproterenol-challenge revealed non-pv triggers in all; in 10 (47.6%) patients the same triggers that were detected during the first procedure were identified again and in the remaining 11 subjects, new triggers were detected. Conclusion: Our findings suggest that in HIV positive AF patients, non-pv triggers are either detected during the first procedure or develop later necessitating repeat ablations. Moreover, the recurrent arrhythmia was observed to be mostly driven by these extra-pv ectopic beats. B-PO LEFT ATRIAL APPENDAGE CLOSURE AFTER ELECTRICAL ISOLATION OF THE APPENDAGE Chintan G. Trivedi, MD, MPH, FHRS, Sanghamitra Mohanty, MD, FHRS, Carola Gianni, MD, PhD, Xianfeng Du, J. David Burkhardt, MD, PhD, Javier E. Sanchez, MD, Patrick M. Hranitzky, MD, FHRS, G. Joseph Gallinghouse, MD, FHRS, Amin Al-Ahmad, MD, FHRS, CCDS, Rodney P. Horton, MD, FHRS, Domenico Della Rocca, Luigi Di Biase, MD, PhD, FHRS and Andrea Natale, MD, FHRS. Texas Cardiac Arrhythmia Institute, Electrophysiology, Austin, TX, St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Institute, Austin, TX, Montefiore Medical Center, NY, Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, Texas Cardiac Arrythmia Institute, Austin, TX, Texas Cardiac Arrhythmia Research, Austin, TX, Albert Einstein College of Medicine at Montefiore Hospital, New York, NY Background: Lifelong oral anticoagulation (OAC) is typically recommended following electrical isolation of left atrial appendage (LAA) for atrial fibrillation (AF), to reduce the risk of thrombus formation in the appendage. LAA occlusion (LAAO) can potentially eliminate the need for OAC. Objective: To present the thromboembolic outcome in a series of cases where LAAO was performed following LAA isolation. Methods: A total of 155 consecutive patients receiving LAAO device post-laai were included in this analysis. The occlusion device was implanted either following thromboembolic events (TE) or because of the presence of bleeding disorders or patientpreference of the device over continuous OAC therapy. The different occlusion devices that were utilized were Watchman, Lariat and surgical clip. In case of Lariat and Watchman, followup transesophageal echo (TEE) was performed at 1, 6 and 12 month post-implantation to confirm device positioning and to exclude leaks. Patients receiving surgical clips had follow-up TEE performed at 1, 3, 6 and 12 months. Results: A total of 88 patients received the LAAO device after experiencing TE events in the post-laai period, whereas 67 patients had the device implanted because of either presence of bleeding disorder or they preferred LAAO over life-long OAC therapy. Mean CHADS 2 -VASc score of the population was 2.9±1.5. Of the 155 patients, 121 (78%) received Watchman, 18 (11.6%) got Lariat and surgical clip was implanted in 16 (10.4%) cases. Follow-up TEE revealed leak 5 mm in 2 patients with Watchman, which were closed by metallic coils later; these two patients remained (temporarily) on OAC therapy until then. One patient with surgical clip was continued on OAC therapy because of high stroke risk. In the remaining patients, OAC and dual antiplatelet therapy were discontinued days and 3-months respectively after the device implantation; all of them were kept on daily aspirin (81 mg) therapy. At the end of 2-years follow-up of device implantation, no TE events were observed in the study population. Conclusion: Our findings suggest LAA occlusion to be a safe and effective alternative to life-long anticoagulation therapy in reducing risk of thromboembolic events following LAA isolation in AF patients. B-PO TWO PROCEDURE OUTCOMES FOR NON-PAROXYSMAL ATRIAL FIBRILLATION USING A CONTACT- FORCE SENSING RADIOFREQUENCY ABLATION CATHETER: LEFT ATRIAL POSTERIOR WALL ISOLATION VERSUS STEPWISE LINEAR ABLATION Robert Knotts, MD, Chirag R. Barbhaiya, MD, FHRS, Cesar Soria, MD, Scott A. Bernstein, MD, David S. Park, MD, PhD, Steven J. Fowler, MD, Douglas Holmes, MD, Anthony Aizer, MD, MS, FHRS and Larry A. Chinitz, MD, FHRS. NYU Langone Health, New York, NY, NYU Langone Medical Center, New York, NY, Leon H. Charney Heart Rhythm Center at NYU Langone Medical Center, New York, NY, New York University - School of Medicine, New York, NY, New York University Medical Center, Cardiology, New York, NY, NYU Medical Center, New York, NY, The Leon H Charney Heart Rhythm Center at NYU Langone Medical Center, New York, NY Background: Unfavorable outcomes for stepwise linear ablation of non-paroxysmal atrial fibrillation (NPAF) in clinical trials may be attributable to pro-arrhythmic effects of incomplete ablation lines. It is unknown if recurrent arrhythmia following stepwise linear ablation is more likely to be successfully ablated compared to recurrent arrhythmia following a more limited initial procedure. The optimal ablation strategy for catheter ablation of NPAF using a contact-force sensing (CFS) radiofrequency ablation (RFA) catheter remains unclear. Objective: To compare 2-procedure outcomes of stepwise linear RFA to left atrial posterior wall isolation in patients undergoing NPAF ablation using a CFS RFA catheter. Methods: We compared clinical outcomes of two cohorts of 100 consecutive NPAF patients undergoing first-time RFA using a CFS RFA catheter. Group 1: stepwise linear ablation (July July 2015); Group 2: left atrial posterior wall isolation (October June 2016). Arrhythmia recurrence was assessed using 2-week event monitors at 3-month intervals following ablation procedures. Results: Baseline characteristics of the two groups were similar. Mean follow-up time was 656 ± 361 days for Group 1 and 436 ± 228 days for Group 2. At 24-month follow up, Kaplan- Meier estimated single procedure arrhythmia free survival was significantly greater in Group 2 compared to Group 1 (76% vs 59%, respectively; p = 0.01), primarily driven by a higher rate of recurrence of atrial tachycardia (12% vs 35%, respectively; p < 0.001). Among patients with recurrent arrhythmia after a single procedure, Group 2 patients were less likely to require repeat ablation compared to Group 1 (6/24 vs 34/41, respectively; p < 0.001) and less likely to recur after repeat ablation (1/6 vs 13/34, respectively; p = 0.001). Conclusion: Compared to stepwise linear ablation, LA posterior wall isolation for catheter ablation of NPAF resulted in a lower incidence of recurrent arrhythmia at 2 years, a lower likelihood of requiring repeat ablation amongst patients with recurrence, and a lower likelihood of recurrence following a second ablation. B-PO LONG-TERM OUTCOME OF PULMONARY VEIN ISOLATION WITH AND WITHOUT ROTOR ABLATION: A SINGLE- CENTER EXPERIENCE Sanghamitra Mohanty, MD, FHRS, Carola Gianni, MD, PhD, Chintan G. Trivedi, MD, MPH, FHRS, Amin Al-Ahmad, MD, FHRS, CCDS, Shane M. Bailey, MD, FHRS, J. David Burkhardt, MD, FHRS, G. Joseph Gallinghouse, MD, FHRS, Rodney P.

49 S536 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Horton, MD, FHRS, Patrick M. Hranitzky, MD, FHRS, Javier E. Sanchez, MD, Luigi Di Biase, MD, PhD, FHRS and Andrea Natale, MD, FHRS. St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Institute, Austin, TX, Texas Cardiac Arrhythmia Institute, Electrophysiology, Austin, TX, Texas Cardiac Arrhythmia, Austin, TX, Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Research, Austin, TX, Texas Cardiac Arrythmia Institute, Austin, TX, Albert Einstein College of Medicine at Montefiore Hospital, New York, NY Background: OASIS trial compared the outcome of pulmonary vein isolation (PVI) plus rotor ablation versus PVI plus non- PV trigger ablation in patients with persistent (Per) and longstanding persistent (LSP) atrial fibrillation (AF). Objective: We evaluated the long-term outcome of PVI with and without rotor ablation Methods: PerAF and LSPAF patients undergoing first ablation procedure at our center were randomized to FIRM+ PVI (peraf: 17, LSPAF: 12) or PVI+ posterior wall (PW) +non-pv trigger ablation (peraf: 15, LSPAF: 14). Results: The per-protocol population was comprised of 29 patients per group. Focal drivers or rotors were detected in all patients in the FIRM+PVI group with a mean of 4.69±1.83 per patient. Procedure time was significantly shorter in the cohort receiving PVI +PW +non-pv trigger ablation [180.6±35.9, and ± 45.4 minutes (p<0.001)]. At 24 months follow-up, 7 (24%) in the FIRM +PVI group and 14 (48%) in the PVI +PW +non-pv trigger ablation group were arrhythmia-free off AAD after a single procedure (log-rank p=0.090). Multivariate analysis revealed FIRM+PVI ablation to be associated with higher risk of recurrence (HR 2.15 [95% CI 1.09 to 4.27], p=0.028). In the LSP AF cohort, significantly higher success rate, was observed in the non-pv trigger ablation population compared to the FIRM ablation group, [9/14 (64%) vs 2/12 (17%), log-rank p= 0.026] (figure). Conclusion: This randomized study compared two ablation strategies in non-paroxysmal AF patients and observed significantly longer procedure time and lower clinical efficacy with PVAI plus rotor ablation than PVAI + PW + non-pv triggerablation, especially in the LSPAF population. Utah, Salt Lake City, UT, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, University of Utah, Sandy, UT, CARMA Center, Sandy, UT, Comprehensive Arrhythmia and Research Management (CARMA) Center, Salt Lake City, UT, University of Utah School of Medicine, Cardiovascular Medicine Division, Salt Lake City, UT, Univ of Utah Health Sciences Center, Div of Cardiology, Salt Lake City, UT Background: Mitral Regurgitation (MR) and Atrial Fibrillation (AF) have a mutual relationship; as in AF renders the mitral valve dysfunctional and MR worsens AF prognosis. The impact of MR on the quality and quantity of LA fibrosis is unknown. Objective: We hypothesized that MR increases the total amount of LA fibrosis in AF patients and affects ablation success rate. Methods: The demographics of 98 patients with MR and AF and 140 patients with AF and no MR was collected. LA fibrosis was quantified before ablation by Late Gadolinium Enhancement MRI (LGE-MRI). After ablation, patients were followed for a median of 71 months. Results: Patients in MR+AF group were significantly older than AF group (76 ± 9.8 vs 65 ± 15, p < 0.001) and had more extensive LA fibrosis (17.9% ± 9.3% vs 10.3% ± 5.3%, p < 0.001). Our regression model, adjusted for possible cofounders, showed MR accounts for 8% more LA fibrosis in AF patients (CI95%: 6.1% - 9.9%, P < 0.001). In AF patients with MR, fibrotic tissue was significantly located to a higher extent on the posterior wall (Figure1-A) (59.7% vs 52.9% in the AF group, p=0.02) than on the anterior wall (15.9% vs 19.7% in the AF group, p=ns). In AF patients, MR comorbidity lowered the chance of AF freedom after ablation (0.58 vs 0.78 in AF group, p < 0.05) (Figure1-B). Conclusion: Mitral regurgitation is associated with a larger extent of LA fibrosis in AF patients, especially on the posterior wall. MR correlates with higher recurrence rate. B-PO MITRAL VALVE REGURGITATION IS ASSOCIATED WITH INCREASED LEFT ATRIAL FIBROSIS Mobin Kheirkhahan, MD, Alex A. Baher, MD, Bettina Nitsche, MD, Takanori Yamaguchi, MD, Bosten Loveless, BS, David C. Peritz, MD, Gagandeep Kaur, Alan Morris, MS, Benjamin E. Hardisty, PhD, Ibolya Csecs, PhD, Franziska Fochler, MD, Qussay Marashly, Mihail G. Chelu, MD, PhD, FHRS and Nassir F. Marrouche, MD, FHRS. CARMA Center, University of

50 Poster Session V S537 PV isolation. During the AF-FICIENT I study, several device enhancements were made to the balloon, sheath, and console. Objective: To evaluate procedural times using the RFB initial design and after enhancements. To compare procedural times with prior published procedural times with point-by-point catheters (RFC) and the second generation cryoballoon system (CB). Methods: Total procedure time (PT), fluoroscopy time (FT), and left atrial dwell time (LAT) were collected with the RFB catheter. Data was categorized as phase 1 (prior to device enhancements) and phase 2 (after enhancements). The same procedural data was collected from 6 published randomized controlled trials or observational studies that compared the second generation CB to RF catheter ablation in PAF patients. Data was compared between the phase 2 RFB and data obtained from the FIRE and ICE study using a t-test. Results: The PT, FT and LAT for CB, RFC, and the RFB are represented in figure 1. When the mean PT (min) were compared to FIRE and ICE, the RFB was significantly lower, 74± 29.5 (RFB) vs 124.4±39 (CB) (p<0.0001) and 140.9±54.9 (RFC) (p<0.0001). The mean FT (min) was significantly lower, 13±7.8 (RFB) vs 21.7±13.9 (CB) (p<0.0001) and 16.6±17.8 (RFC) (p<0.01). The LAT (min) was also significantly lower, 43±21.8 (RFB) vs 92.3±31.4 (CB) (p<0.0001) and 108.6±44.9 (p<0.0001). Conclusion: When compared to the largest randomized controlled trial of the CB and RFC for treatment of PAF, preliminary analysis of PT, FT, and LAT is favorable for the RFB. B-PO PROCEDURE TIME USING THE NOVEL APAMA RADIOFREQUENCY BALLOON. DATA FROM THE AF- FICIENT I STUDY Amin Al-Ahmad, Ian G. Crozier, MBCHB, MD, FHRS, Iain Melton, MD, MBChB, Matthew G. Daly, Petr Neuzil, MD, PhD, Audrius Aidietis, MD, Gediminas Rackauskas, MD, Darren A. Hooks, PhD, MBChB, Matthew R. Webber, MD, Bradley P. Knight, MD, FHRS and Vivek Y. Reddy, MD. Texas Cardiac Arrhythmia Institute, Austin, TX, Canterbury Health Limited, Christchurch, New Zealand, Christchurch Hospital, Christchurch, New Zealand, Cardiology Department, Christchurch Public Hospital, Christchurch, New Zealand, Na Homolce Hospital, Prague, Czech Republic, Vilnus University Hospital, Vilnius, Lithuania, Department of Cardiovascular Medicine, Vilnius University, Santariskiu Klinikos Hospital, Vilnius, Lithuania, Haut Leveque Hospital, Pessac, France, Wellington Regional Hospital, Wellington, New Zealand, Northwestern University, Feinberg School of Medicine, Chicago, IL, Icahn School of Medicine at Mount Sinai, New York, NY Background: The Apama radiofrequency balloon (RFB) catheter has been recently evaluated in humans with PAF in the AF-FICIENT I study. The catheter allows rapid, one shot B-PO PROGRESSION OF THE ARRHYTHMIA IN LONG- STANDING PERSISTENT ATRIAL FIBRILLATION: INSIGHTS FROM A SINGLE-CENTER STUDY Sanghamitra Mohanty, MD, FHRS, Chintan G. Trivedi, MD, MPH, FHRS, Carola Gianni, MD, PhD, Domenico Giovanni Della Rocca, MD, J. David Burkhardt, MD, FHRS, Javier E. Sanchez, MD, Patrick M. Hranitzky, MD, FHRS, G. Joseph Gallinghouse, MD, FHRS, Amin Al-Ahmad, MD, FHRS, CCDS, Rodney P. Horton, MD, FHRS, Xianfeng Du, MD, Domenico Giovanni Della Rocca, MD, Luigi Di Biase, MD, PhD, FHRS and Andrea Natale, MD, FHRS. St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Institute, Electrophysiology, Austin, TX, Texas Cardiac Arrhythmia Institute, Austin, TX, Texas Cardiac Arrhythmia Institute, St. David s Medical Center, Austin, TX, Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, Texas Cardiac Arrythmia Institute, Austin, TX, Texas Cardiac Arrhythmia, Austin, TX, Texas Cardiac Arrhythmia Research, Austin, TX, Albert Einstein College of Medicine at Montefiore Hospital, NY, NY, Albert Einstein College of Medicine at Montefiore Hospital, New York, NY Background: Long-standing persistent atrial fibrillation (LSPAF)

51 S538 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 is considered as an advanced stage of the disease with limited success rate after catheter ablation. Objective: We evaluated the time to relapse as well as the prevalent triggering foci in LSPAF patients experiencing postablation recurrence. Methods: A total of 212 LSPAF patients that received their first two AF ablation at our center were included in this analysis. All received PVI (or re-isolation) plus isolation of posterior wall, superior vena cava and coronary sinus during the first two procedures. Additionally, non-pv triggers detected by isoproterenol-challenge, from sites other than left atrial appendage (LAA) were ablated. However, none of these patients received LAA isolation (LAAI) during the first two procedures Results: Of the 212 patients, 169 (80%) were male and mean AF duration was 79.5±48 months. During follow-up of over 7 years after the 2 nd ablation, 121 (57%) cases experienced recurrence. Median time to recurrence was 14.7 ( ) months (figure). 99/121 (82%) patients with recurrence underwent redo ablation. PV reconnection was not detected in any of these patients. LAAI was performed in all; upon detection of triggers in 64 (64.6%) and empirical isolation of LAA in the absence of detectable triggers in 35 (35.4%) patients. Two years after the redo ablation, 80/99 (80.7%) remained on sinus rhythm off antiarrhythmic drugs. Conclusion: Our results suggest that in LSPAF, the arrhythmia evolves in time resulting in recurrences driven solely by triggers from the left atrial appendage. Thus LAAI should be considered as part of the ablation approach in these patients. Objective: To assess the rate of tissue excitability identified via high density voltage mapping after CA and to examine the relationships between the need for PV touch-up, baseline patient characteristics, and atrial arrhythmia recurrence. Methods: The population included consecutive PAF patients having CA followed by bidirectional block confirmation, then voltage mapping with a PENTARAY NAV Catheter and CARTO 3 Mapping System to verify PVI. Touch-up ablation was performed with an RF catheter at sites where breakthrough was identified. Recurrence was analyzed with Kaplan-Meier and Cox regression models. PV touch-up and baseline risks were tested for significance as predictors. Results: 77 PAF patients (age: 66.1±11.6, CHADS 2 : 1.8±1.0) were followed for 1.2±0.3 yr after CA. PV touch-up was required in 59 patients (76.6%). Additional ablations outside of PV were required in 27 patients (35.1%). Kaplan-Meier estimates of freedom from atrial arrhythmia recurrence at one year are 62±6% overall, are lower for patients requiring PV touch-up (58±6% vs. 78±10%) and for patients with CHADS 2 scores of 3 or higher (33±12% vs. 69±6%). Cox regression models show that the need for PV touch-up increases recurrence risk (p=0.045, HR=2.6) after adjusting for hypertension (p=0.113, HR=5.0) and congestive heart failure (p=0.013, HR=2.6). Conclusion: After high density voltage mapping to ensure PVI, 76.6% of patients required PV touch-up after CA. These patients had higher recurrence at 1-year follow-up. Our results suggest that patients requiring touch-up may have additional conditions that make them more difficult to treat and initial CA lesions may be less durable than previously assumed. B-PO B-PO TOUCH-UP AND RECURRENCE RATES AFTER VOLTAGE MAPPING FOR VERIFICATION OF PULMONARY VEIN ISOLATION (PVI) FOLLOWING CRYOABLATION (CA) OF PAROXYSMAL ATRIAL FIBRILLATION (PAF) Rajesh Malik, MD, Tina D. Hunter, PhD, Christina Parks and Bobby Malik. Pee Dee Cardiology Associates, Florence, SC, CTI Clinical Trial and Consulting Services, Covington, KY, Mcleod Regional Medical, Florence, SC, VCOM-Carolinas, Spartanburg, SC Background: The consensus treatment goal for PAF ablation is PVI. Following CA, the standard approach to confirm PVI is through entrance/exit block using a circular mapping catheter. PV reconnection is a common reason for long term arrhythmia recurrence. PVI enhancement may be achieved via electrical inexcitability with high density voltage mapping and ablation of identified conduction gaps. ATRIAL FIBRILLATION ABLATION: A DAY CASE PROCEDURE James McCready, MRCP, Justo Julia-Calvo, MD, John Silberbauer, MD, Sean O Nunain, MD, FRCP, Mihir Patel, MBBS and Felicity Champney. Brighton and Sussex University Hospitals, Brighton, United Kingdom Background: Catheter ablation is a effective intervention to improve symptoms in patients with atrial fibrillation (AF), however limited data exists on length of stay and day case procedures. Adopting a day case (DC) approach may improve patient experience and reduce the burden on hospital resources. Objective: Since 2012 DC catheter ablation for AF has been carried out routinely for most patients at our centre. This study will demonstrate this has been achieved without increasing readmission. Methods: A retrospective analysis of consecutive elective patients undergoing catheter ablation for AF was performed. Patients undergoing both radiofrequency (RF) and cryoablation were included. Those whose case finished after 4pm were considered not suitable for DC discharge as the Day Unit closes at 8pm and minimum time to discharge is 4 hours. Those who experienced major complication were also considered unsuitable; however no demographic factors were used to determine suitability. Results: Between January 2012 and June 2017, 936 ablation procedures for AF were performed. Among them, 413 (44.1%) were performed with the Cryoballoon catheter and 521 (55.7%) with RF. Overall, 709 patients (75.8%) met criteria for DC discharge. When analysing causes that rendered patients unsuitable for DC discharge, late finish accounted for 187 (20.0%) and major complication for 27 (2.9%). Of patients who were suitable for DC discharge, 224 (31.6%) did not go home the same day. Arrhythmia accounted for 11 (4.9%),

52 Poster Session V S539 chest pain 12 (5.4%), minor vascular complication 14 (6.3%), hypotension 18 (8.0%), GA 61 (27.2%), no reason/operator choice 99 (44.2%) and other 11 (4.9%). Within 30 days post procedure, 48 of 936 patients (5.1%) required readmission. DC patients had a similar 30-day readmission incidence (3.5% v. 6.9%; p=0.26) than those who stayed overnight following their ablation procedure. The mean time to readmission for those discharged the same day was 10.5 ± 5.5 days v. 7.2 ± 2.5 days for those staying overnight. Conclusion: Discharge on the same day can be achieved in up to 85% of suitable patients undergoing an AF ablation, without increasing the incidence of re-admission. Day Case discharge also has the potential to improve patient experience whilst reducing the cost for the overnight stay. B-PO TECHNIQUES FOR REDUCING AIR BUBBLE INTRUSION INTO LEFT ATRIUM DURING CATHETER ABLATION PROCEDURES: EX VIVO STUDY WITH A HIGH- RESOLUTION CAMERA Mitsuru Takami, MD, PhD, Ryudo Fujiwara, Doctor, Yoichi Kijima, MD, PhD, Ryoji Nagoshi, MD, PhD, Amane Kozuki, MD, PhD, Hiroyuki Shibata, MD, Yasuhide Mochizuki, MD, PhD, Yusuke Fukuyama, MD, Daichi Fujimoto, MD, Shunsuke Kakizaki, MD, Eri Masuko, MD, Shoukan Kyo, MD, Tomohiro Miyata, MD and Junya Shite, MD, PhD. Osaka Saiseikai Nakatsu Hospital, Osaka, Japan, Saiseikai Nakatsu Hospital, Osaka, Japan Background: Air embolism is a serious complication during catheter ablation procedures. Objective: The purpose of this study is to know when air bubbles enter the left atrium (LA) and how to reduce the air bubbles intrusion. Methods: An ex vivo study was performed using a simulated silicon heart model with a high-resolution camera for monitoring air bubbles in LA. Results: A total of 270 catheter ablation processes in radiofrequency catheter and cryoballoon were tested. Large numbers of small bubbles were often seen during sheath flushing with a syringe (median [quartiles]: 35 [20-53] in SL0 TM sheath, 33 [18-45] in Agilis TM sheath, 96 [84-100] in FlexCath TM sheath) and cryoballoon inflation/freeze/deflation (49 [37-59]). Large air bubbles ( 1.5mm) were often seen during cryoballoon insertion inflation/freeze/deflation. Massive large air bubbles were seen during circular mapping catheter (OPTIMA TM ) insertion with an inserter (11 [2-16]). In terms of techniques for reducing air bubbles intrusion, slow sheath flushing (8cc/5sec) significantly reduced the number of air bubbles compared with normal sheath flushing (8cc/1sec) (SL0 TM : 35 vs 0, Agilis TM : 33 vs 0, FlexCath TM : 96 vs 0, p<0.001) (Figure). Before cryoballoon insertion, a temporary inflation and remove air bubbles was the most effective method for reducing the air bubbles on the balloon surface. Circular mapping catheter insertion without an inserter significantly decreased the number of massive large air bubbles, compared with the insertions with an inserter (21 vs 0, p<0.001). Conclusion: Air bubbles enter the LA at specific times during catheter ablation processes, which can be reduced using several techniques. B-PO THE CHARACTERISTICS OF PULMONARY VEIN STENOSIS COMPLICATING ABLATION FOR ATRIAL FIBRILLATION: COMPARISON BETWEEN RADIOFREQUENCY AND CRYOBALLOON ABLATION Yukihiro Inamura, MD, Junichi Nitta, MD, Takashi Ikenouchi, MD, Kazuya Murata, MD, Tatsuhiko Hirao, MD, Tomomasa Takamiya, MD, Nobutaka Kato, MD, Akira Sato, MD, Yoshihide Takahashi, MD, Masahiko Goya, MD and Kenzo Hirao, MD. Japanese Red Cross Saitama Hospital, Saitama, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: Pulmonary vein (PV) isolation was established treatment for patients with paroxysmal atrial fibrillation (AF). However this procedure is associated with the development of PV stenosis. Previous study reported Cryoballoon ablation can progress PV stenosis as well as radiofrequency ablation. However, there were few studies of PV stenosis comparison between radiofrequency and Cryoballoon ablation. Objective: We evaluated the difference of PV stenosis complicating ablation for AF between radiofrequency and Cryoballoon ablation. Methods: For this prospective observational study, we enrolled 753 patients ablated with the second generation 28mmcryoballoon (Cryo-group) and 913 with radiofrequency catheter (RF-group) for paroxysmal atrial fibrillation between January 2013 and September 2017 at our institution. After PV isolation, if non-pv AF foci were documented, we added ablation with radiofrequency catheter for non-pv AF foci in both group. PV stenosis was defined as a more than 75% stenosis and total occlusions in computerized tomography after 1 year from PV isolation. Results: There were 12 PV stenosis patients (16 PVs) in RFgroup, 3 left superior(ls) PVs, 8 left inferior(li) PVs, and 5 right inferior(ri) PVs. Three patients had multi PVS (LS+LI, LI+RI, LS+LI+RI), and there were 3 PVS patients (3PVs) in Cryo-group, 1 LS PV and 2 right superior (RS) PVs. PV stenosis occurred more frequently in RF-group than Cryo-group (P=0.047), however superior PV stenosis occurred more frequently in Cryogroup (P=0.005). In cases with only inferior PVS, 7 of 9 patients did not complain any symptoms, the other 2 patients presented mild dyspnea. On the other hand, 5 of 6 superior PVS cases suffered from serious symptoms, such as repetitive hemoptysis, dyspnea, and pulmonary hypertension.

53 S540 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Conclusion: Cryoballoon ablation had less PV stenosis than radiofrequency ablation, however caused superior PV stenosis which could cause severe symptoms. B-PO SAFETY AND USEFULNESS OF IDARUCIZUMAB FOR HEMORRHAGIC EVENTS ASSOCIATED WITH CATHETER ABLATION IN PATIENTS WITH ATRIAL FIBRILLATION UNDER AN ANTICOAGULANT STATUS WITH DABIGATRAN Rena Nakamura, Kaoru Okishige, MD, Takatoshi Shigeta, Master, Takuro Nishimura, MD, Hideshi Aoyagi, PhD, Yasuteru Yamauchi, Tetsuo Sasano, MD, PhD and Kenzo Hirao, MD. Japan Red Cross Yokohama Bay City Hospital, Yokohama, Japan, Yokohama Red Cross Hospital; Cardiology Department, Yokohama, Japan, Yokohama Bay Red Cross Hospital, Yokohama, Japan, Japan Red Cross Yokohama City Bay Hospit, Yokohama, Japan, Yokohama City Minato Red Cross Hospital, Yokohama City, Kanagawa pref., Japan, Tokyo Medical and Dental University, Tokyo, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: Idarucizumab (IC) is synthetized to reverse the anticoagulant effects of dabigatran (DB), and its mode of action has been proven to be rapid without provoking serious adverse effects. Objective: This study aimed to investigate the safety and usefulness of IC for hemorrhagic adverse events associated with catheter ablation (CA) in patients with atrial fibrillation (AF). Methods: In a total of 537 patients with AF performed CA. 341 patients had interrupted direct oral anticoagulants (DOACs) from 12 to 24 hours before the CA procedure until the end of the session (Group A) and the remaining 196 patients had uninterrupted dabigatran throughout the procedure(group B). In patients with Group B, A 5g intravenous dose of IC was administered when a bleeding event was provoked by the CA procedure. We compared hemopericardiums between 2 groups. Results: In Group A, 16 patients suffered from hemopericardiums (Group C) and in Group B 4 patients did (Group D). IC was able to successfully neutralize the anticoagulant effects of dabigatran resulting in better hemostasis without pericardiocentesis, and the period of hospitalization was significantly shorter compared to that with the conventional method (see Table). Conclusion: IC seemed to be valuable in resolving hemopericardiums associated with CA. The comparison of clinical parameters between Group C and Group D. Group C n=16 Group D n=4 P value age/y 72.5± ± male (%) 7 (43) 3 (75) 0.30 Cardiac tamponade (%) 8 (50) 1 (25) 0.41 Creatinine/mg/dL (%) Day to restart anticoagulant drug 2.5±4.4 2± Day to discharge 5±4.1 3± Thrombotic event after the operation (%) 1 (6) 0 (0) 0.70 B-PO DISTINCT CHARACTERISTICS OF HUMAN VENTRICULAR FIBRILLATION IN ITS INITIAL PHASE Michel Haissaguerre, MD, Josselin Duchateau, Ghassen Cheniti, MD, Stephane Puyo, PhD, Arnaud Denis, MD, Hubert Cochet, MD, PhD, Marianna Meo, PhD, Takeshi Kitamura, Masateru Takigawa, Antonio Frontera, Konstantinos George Vlachos, MD, PhD, Grégoire Massoullie, MD, Anna Lam, MD, Felix Bourier, MD, Thomas Pambrun, Nicolas Welte, Nicolas Derval, MD, Sana Amraoui, Nicolas Klotz, MD, Frederic Sacher, MD, Pierre Bordachar, MD, PhD, Sylvain Ploux, MD, Philippe Ritter, MD, Pierre Jais, MD, Edward J. Vigmond, PhD, Mark Potse, PHD, Richard D. Walton, PhD, Remi Dubois, Olivier Bernus, PhD and Meleze Hocini, MD. IHU LIRYC - CHU Bordeaux, Pessac, France, CWT Meetings & Events, Mélissa Pernot, Boulogne-Billancourt Cedex, France, Hôpital Haut- Lévêque, 33600, France, CHU Bordeaux, Pessac Cedex, France, Pessac, France, LIRYC institute - Hôpital Haut Lévêque, Pessac Cedex, France, Pessac,Bordeaux, France, CHU Clermont-Ferrand, Boulogne-Billancourt Cedex, France, Hôpital Cardiologique du Haut-Lévêque - CHU de Bordeaux, Bordeaux- Pessac, France, Bordeaux, France, Deutsches Herzzentrum, Munich, Germany, Groupe Hospitalier SUD, Pessac, France, Hopital Cardiologique Du Haut-Leveque, Pessac, France, Bordeaux University, Talence, France, Hôpital Haut-Lévèque, Pessac, France, LIRYC Institute/ Bordeaux University Hospital, Bordeaux, France, CHU Bordeaux, Bordeaux, France, Bordeaux University Hospital (CHU), Pessac, France, University Hopital of Bordeau, Hopital Du Haut Leveque, Pessac 33600, France, Hôpital Haut-Lévêque, Bordeaux, France, University Bordeaux, Pessac, France, Sacrt-coeur Hospital, Montreal, QC, Canada, Université de Bordeaux, Pessac, France, Hopital Cardiologique Haut Leveque - Université Bordeaux, IHU LIRYC, Pessac, France Background: Ventricular fibrillation (VF) progresses rapidly from an initial organized stage to chaotic fibrillation. The characteristics of initial drivers, that may be critical for therapeutic interventions, have not been investigated. Objective: To characterize the initial drivers of Human VF Methods: We evaluated 51 patients (44±10 years) who survived VF associated with ischemic heart disease in 15, cardiomyopathy in 14 and Brugada syndrome in 22. VF was mapped by intracardiac and body-surface recordings to analyze spatial organization, cycle lengths (CL), and drivers at the origin of wavefronts. We performed endocardial and epicardial mapping during sinus rhythm. The abnormal substrate was identified as areas of low voltage ( 1mV) and fragmented signals ( 70ms). Results: We mapped 69 episodes of spontaneous (n=12) or induced (n=57) VF for 17±10 s. The VF CL decreased from 208±28 to 172±25 ms (p<0.001) with the fastest acceleration consistently occurring in the initial 5 s. Initial organized VF, lasting 4.3 ± 1s, showed recurring wavefront sequences arising from distinct driver areas of focal or reentrant activity. These drivers were specifically associated with the abnormal ventricular substrate: in Brugada syndrome, they originated from individual locations in the right ventricle whereas in ischemic heart disease or cardiomyopathy, they originated dominantly from scar borderline in the left ventricle. In contrast, during the disorganized VF phase, the drivers were disseminated in both ventricles producing widespread unstable reentries without specific link with underlying ventricular substrate. In 32 patients, the driver areas were ablated using radiofrequency energy resulting in arrhythmia-free outcome in 27 patients at 20±19 months follow- up. Conclusion: The early phase in which human VF appears electrocardiographically well-organized, is unique as it is associated with a limited number of drivers distinctly related to underlying abnormal substrate. These primary drivers will then rapidly accelerate and disseminate to establish disorganized fibrillation.

54 Poster Session V S541 B-PO THE DISTINCT ELECTROPHYSIOLOGICAL CHARACTERISTICS OF VENTRICULAR ARRHYTHMIAS ORIGINATING FROM PARA-HISIAN REGION: IMPACT OF ELECTROCARDIOGRAPHIC PARAMETERS TingChun Huang, MD, Fa-Po Chung, MD, Yenn-Jiang Lin, MD, PhD, Li-Wei Lo, MD, PhD, Shih-Lin Chang, MD, PhD, Yu-feng Hu, MD, Ling Kuo, Hsing-Yuan Li, PhD, Quang-Minh Hoang, Simon Salim, MD, Vu Van Ba, Jennifer Jeanne B. Vicera, Rubiana Sukardi, Cheng-I Wu, Chih-Min Liu, MD, Chieh-mao Chuang, Ting-Yung Chang, MD, Chye-Gen Chin, Chun Chao Chen and Shih-Ann Chen, MD. Heart Rhythm Center and Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veteran General Hospital, Taipei, Taiwan, Taipei, Taiwan, Fellow in Training - Taipei Veteran General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei City, Taiwan Background: Ventricular arrhythmias (VAs) could originate from the conducting system or myocardium within the parahisian region (Fig. 1A&B). Identification of the entity is crucial for potential ablation strategies. Objective: We sought to use parahisian pacing with different current to establish a novel ECG algorithm to differentiate the mechanism of VA from parahisian area. Methods: We enrolled 30 patients (46.7% male; mean age 52.6±14.1) without parahisian scars. Different currents were applied to the parahisian region to capture the local myocardium and conduction system with different wideness of QRS morphologies at a pacing cycle length of 400 ms. The paced ECG features were analyzed and validated clinically. Results: Six pacing beats with wide and narrow complexes in 2:1 ratio in each patient were analyzed (n =180) with a mean pacing current of 2.37±2.27mA and ma (p <0.05), respectively. Based on logistic regression analysis, lead II R peak duration (from QRS beginning to R peak) 85 ms and V2S/V3R ratio 1.24 were identified to significantly differentiate two different mechanisms of VAs from parahisian area (Fig. 3A&B). The novel stepwise algorithm was established as figure 3 to discriminate the entities of parahisian VAs with a sensitivity of 95.8% and a specificity of 41.9%. Based on the algorithm, 6 patients with 3 VAs from myocardium and 5 VAs from conducting system were examined. The sensitivity, specificity, and accuracy were 66.7%, 80%, and 75% respectively. Conclusion: The novel stepwise algorithm derived from parahisian pacing provides moderate accuracy in discrimination of parahisian VAs with different electrophysiological features. B-PO CLINICAL OUTCOMES AND FUNCTIONAL CHARACTERIZATION OF αt-catenin (CTNNA3) IN PATIENTS OF ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY Yenn-Jiang Lin, MD, PhD, Yun-Yu Chen, BS, Jyh-Ming J. Juang, MD, PhD, Fa-Po Chung, MD, Ling Kuo, Ting-Yung Chang, MD, Quang Minh Hoang, Jennifer Jeanne B. Vicera, Simon Salim, MD, Vu Van Ba, Rubiana Sukardi, Cheng-I Wu, Chih-Min Liu, MD, Chieh-mao Chuang, TingChun Huang, Chye Gen Chin, Chun Chao Chen and Shih-Ann Chen. Heart Rhythm Center and Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei, Taiwan, National Taiwan University Hospital, Taipei, Taiwan, Fellow in Training - Taipei Veteran General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei City, Taiwan Background: Arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD/C) is an inherited sudden cardiac death syndrome characterized by abnormal structure of right ventricle. Objective: This study proposes to identify the desomsomal and non-desmosomal mutations in penetrance of missing genetic determinants in Taiwanese population. Methods: We applied whole exome sequencing using Nextgeneration sequencing. A total of 93 definite ARVD/C probands were enrolled, who were compared with 520 healthy controls. ARVD/C diagnosis was based on Task Force Criteria. Results: In all 93 probands, twenty-three probands were autopsy-proved forensic cases as first manifestation of sudden cardiac death (SCD). Among all ARVD/C related genes, only CTNNA3 (N=6; P=0.04) and PKP4 mutations (N=4, 100% in male; P=0.03) were associated with increased risk of SCD/ VF (Table 1). ARVD/C probands with mutations of CTNNA3 were associated with first manifestation of SCD in 6 probands (85.7%). We showed increased age-adjusted risk in female with CTNNA3 mutation compared with the reference group of female without CTNNA3 mutation (Hazard ratio [HR]: 9.12, 95% CI: , P<0.001; Table 2), male without CTNNA3 mutation also showed higher risk in SCD/VF events compared with reference group (HR: 2.53, 95% CI: , P=0.03). However, male with CTNNA3 mutation did not show significant difference compared with the reference group. Conclusion: This study reports novel CTNNA3 mutations for early malignant electric decoupling in patients with ARVD/C. Gender and pathogenesis beyond desmosome might affect the clinical outcomes in patients with ARVD/C.

55 S542 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO LONG-TERM FREEDOM FROM PREMATURE VENTRICULAR COMPLEXES FOLLOWING SUCCESSFUL CATHETER ABLATION Derek Lee, BS, Kurt S. Hoffmayer, MD, Jonathan C. Hsu, MD, Amir A. Schricker, MD, Ulrika Birgersdotter-Green, MD, Farshad Raissi, MD, Gregory K. Feld, MD and David E. Krummen, MD, FHRS. University of California San Diego and VA San Diego Healthcare System, San Diego, CA Background: Premature ventricular complex (PVC) ablation success at 6 months has been reported as 80-95%. Few studies exist that evaluate the long-term outcomes beyond 1 year following successful ablation. Objective: We hypothesized that long-term PVC ablation success may be similarly high and that regional differences may affect ablation effectiveness. Methods: In this IRB-approved study, pts who underwent PVC ablation from May 2010 to May 2015 were analyzed for long-term ablation success. Pts were included if they had acute procedural success and clinical follow-up 12 months. Acute success was defined as elimination of PVCs without intraoperative recurrence on or off an isoproterenol challenge. Long-term success was defined as the absence of recurrent PVC symptoms or ECGs demonstrating PVC recurrence at follow-up visits. PVC sources were identified as the site of PVC termination from intraprocedural mapping and ablation. We used ANOVA with Bonferroni correction to determine whether PVC source location influenced procedural outcome. Results: In 44 pts (age 53.5±4.8 years; LVEF 56.3±3.7%, preablation PVC burden 19.7±3.3%), overall long-term ablation success was 75% (33/44 pts) at a mean of 36±6 months. Success was greatest for RVOT sites (21/22 cases, 95%) versus non-rvot sites (12/22 cases, 55%, p<0.01, Table 1). Pt characteristics were similar between the long-term success and failure groups for age, co-morbidities, and echocardiographic parameters (p 0.05). Conclusion: Freedom from PVCs following successful ablation is approximately 75% at 3 years with excellent results for RVOT sources. Additional work is required to improve the ablation success at non-rvot locations. B-PO QUANTITATIVE ASSESSMENT OF LEFT VENTRICULAR SCAR BY INTRACARDIAC ECHOCARDIOGRAPHY- COMPARISON WITH VOLTAGE MAP AND CONTRAST- ENHANCED CARDIAC MRI IMAGING Yuji Wakamatsu, MD, Koichi Nagashima, MD, PhD, Keiko Takahashi, M.D., Yasuo Okumura, MD, PhD, Ryuta Watanabe, MD, Masaru Arai, Sayaka Kurokawa, Toshiko Nakai, MD, Ichiro Watanabe, MD, PhD, Satoshi Kunimoto, MD and Atsushi Hirayama. Nihon University School of Medicine, Tokyo, Japan, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan, Nihon University, Tokyo, Japan, Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan, Nihon University, School of Medicine, Tokyo, Japan Background: Scar tissue has known to be the substrate of ventricular tachycardia (VT) due to structural heart disease. Left ventricular endocardial voltage has been used for identifying endocardial scar. However, epicardial and intramural scar are often difficult to identify from endocardial electroanatomic mapping. Contrast-enhanced MRI (CE-MRI) image has been used to identify spatial distribution of the left ventricular scar formation. However, CE-MRI is contraindicated in the presence of renal failure and limited data is available in the presence of cardiac implantable device because of noise. Signal intensity units (SIUs) on intracardiac echocardiography (ICE) images might be an alternative to the CE-MRI assessed for identifying scar tissue in the left ventricle (LV). Objective: The aim of this study was to assess the correlation of electroanatomic and CE-MRI parameters and SIU for detecting the LV scar tissue. Methods: Two-dimensional ICE images were obtained in 12 patients with VT and were used for 3D reconstruction of the LV using CARTOMERGE module. SIUs on the ICE images, lowvoltage zones (LVZs) on the electroanatomic maps, and late gadolinium-enhancement areas on the CE MRI images were compared. Results: Voltage-defined LVZs had increased signal intensities compared to normal myocardium (89.9±15.3 SIU vs. 56.9±18.0 SIU, p=0.0001), and the optimal cutoff was 86.5 SIU. Positive DE areas also had increased signal intensities compared to normal myocardium (89.5±6.6 SIU vs. 63.5±25.6 SIU, p=0.0159). Conclusion: SIU obtained from ICE may be useful in online identification of the structural substrate for VT.

56 Poster Session V S543 B-PO OMNIPOLE ELECTROGRAM VECTORS DEFINE THE DIASTOLIC COMPONENT IN A SCAR MEDIATED REENTRANT VT CIRCUIT John Whitaker, Adam Connolly, PhD, Steve Kim, Steven E. Williams, BSc MB ChB MRCP, Thierry Aubriot, RN, Rahul Mukherjee, MBBS, Louisa O Neill, Srijoy Mahapatra, MD, FHRS, Stephen Morgan, MD, Brendan Murfin, MD, Carla Richardson, MD, Luigi Camporota, MD, PhD, Steven A. Niederer, DPhil in Computer Science, Sébastien Roujol, Matthew James Wright, MBBS, PhD, FHRS, Reza Razavi, John Silberbauer, MA, MBBS, MD, Martin J. Bishop, PhD and Mark D. O Neill. King s College London, London, United Kingdom, Kings College London, London, United Kingdom, Abbott, Austin, TX, St. Jude Medical, Woluwe Saint Pierre, Belgium, London, United Kingdom, St. Jude Medical Inc, Edina, MN, St. Thomas Hospital, Cardiology, London, United Kingdom, King s College London, United Kingdom, Sussex Cardiac Centre, Haywards Heath, United Kingdom, King s College London, London, United Kingdom, St. Thomas Hospital, London, United Kingdom Background: Defining activation patterns in ventricular tachycardia (VT) is dependent on accurate assignment of local activation time (LAT). Alternatively, omnipolar EGMs calculated from regularly fixed spaced electrodes may be used to estimate direction of wavefront activation, independent of LAT. Objective: To compare the pattern of activation from traditional LAT maps with omnipoles vectors to define pattern of activation in a scar related re-entrant VT. Methods: Unipolar electrograms were collected using the HD Grid 16 electrode mapping catheter from a single pig in VT following antero-septal MI. LATs were computed from the time corresponding to the minima in the temporal derivative of the unipolar electrograms; these LATs were then interpolated on to the endocardial geometry. Omnipole EGMs were used to estimate the direction of wavefront propagation. Results: Interpolated LAT plots of showed significant activation time heterogeneity (proximal early and late activation) in a region demonstrating extensively fractionated unipolar electrograms (Fig. A). Omnipolar-estimated activation directions showed starburst activation patterns (Fig. C) in the same region, corresponding to localised activation breakthrough and the earliest systolic activity. Elsewhere, omnipolar vectors showed similar activation directions consistent with mid systolic activation (Fig. B). Conclusion: Omnipole electrograms provide complementary information regarding activation patterns in VT, independent of LAT. Future work should focus on real-time comparison of the efficacy of standard mapping techniques versus the omnipolar scheme. B-PO CONCEALED MYOCARDIAL STRUCTURAL ABNORMALITIES IN PATIENTS WITH UNEXPLAINED VENTRICULAR ARRHYTHMIAS: ROLE OF ENDOMYOCARDIAL BIOPSY Michela Casella, MD, PhD, Antonio Dello Russo, MD, PhD, Domenico Della Rocca, Carola Gianni, MD, Pasquale Santangeli, MD, Alessio Gasperetti, Giulia Vettor, MD, Martina Zucchetti, MD, Elena Sommariva, PhD, Valentina Catto, PhD, Andrea Natale, MD, FHRS and Claudio Tondo, MD, PhD. Monzino Cardiac Center, Milan, Italy, TCAI, Austin, Austin, TX, University of Pennsylvania, Philadelphia, PA Background: The diagnosis of concealed cardiomyopathies in patients with ventricular arrhythmias (VAs) is one of the major challenging issues faced by physicians. Objective: We aimed at evaluating the diagnostic value of endomyocardial biopsy (EMB) and report the underlying possible causes of unexplained VAs. Methods: From January 2010 to October 2017, consecutive patients with unexplained VAs underwent a complete diagnostic work-out, including EMB and genetic testing. Results: Eighty-two patients were enrolled (mean age: 41±13 years; 84.1% male). The presenting arrhythmic manifestation was syncope/aborted cardiac arrest in 30 (36.5%) patients, sustained ventricular tachycardia (VT) in 9 (11%), nonsustained VT in 19 (23.2%) and frequent premature ventricular complexes in 24 (29.3%). Overall, 296 biopsies were collected (3.6/patient). The incidence of procedure-related complications was 3.7% (n=3): 2 major complications (1 dissection of right external iliac artery treated with endovascular stent placement, 1 thrombotic occlusion of left superficial femoral artery which required surgical treatment) and 1 minor complication (1 groin site hematoma treated conservatively) occurred. The following final diagnoses were made: arrhythmogenic cardiomyopathy (ACM) in 39 (47.6%) patients; myocarditis in 16 (19.5), idiopathic dilated cardiomyopathy in 5 (6.1%), myocarditis in ACM and cardiac sarcoidosis in 3 (3.7%) each, left ventricular noncompaction and mitochondrial disease in 1 (1.2%) each, nonspecific cardiac disease in 7 (8.5%), others in 7 (8.5%) cases. Among patients with myocarditis, the diagnostic yield of EMB (histological analysis, immunohistochemistry and polymerase chain reaction) was 75%. Among ACM patients, the diagnostic yield was 69%, but raised to 84.6% when results of genetic testing were considered (p=0.01). Conclusion: In our series, approximately half of the patients with unexplained VAs had a final diagnosis of ACM. The

57 S544 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 diagnostic yield of EMB in patients with suspected ACM improved significantly by integrating histological analysis with genetic findings. B-PO THE ROLE OF CARDIAC MAGNETIC RESONANCE IN THE DIFFERENTIAL DIAGNOSIS BETWEEN MYOCARDITIS AND ARRHYTHMOGENIC CARDIOMYOPATHY PRESENTING WITH VENTRICULAR ARRHYTHMIAS Michela Casella, MD, PhD, Antonio Dello Russo, MD, PhD, Carola Gianni, MD, Domenico Della Rocca, MD, Pasquale Santangeli, MD, Alessio Gasperetti, MD, Daniele Andreini, MD, PhD, Gianluca Pontone, MD, Saima Mushtaq, MD, Edoardo Conte, MD, Andrea Natale, MD, FHRS and Claudio Tondo, MD, PhD. Monzino Cardiac Center, Milan, Italy, TCAI, Austin, Austin, TX, University of Pennsylvania, Philadelphia, PA Background: Myocarditis may affect the right ventricle, causing structural abnormalities that are typical of arrhythmogenic cardiomyopathy (ACM). Of note, a significant amount of patients with myocarditis fulfills the cardiac magnetic resonance (CMR) criteria set forth by the 2010 Task Force for ACM, thereby increasing the risk of misdiagnosis. Objective: We aimed at assess the role of CMR in the differential diagnosis between myocarditis and ACM in patients presenting with ventricular arrhythmias. Methods: Consecutive patients with suspected myocarditis or ACM and presenting with ventricular arrhythmias underwent a complete diagnostic work-out, which included clinical and family history, physical examination, laboratory tests, chest X-ray, 12-lead electrocardiogram, ECG interpretation of the index arrhythmia, 2-D echocardiography, CMR, endomyocardial biopsy, genetic testing. Results: Overall, 40 patients were enrolled in the study (mean age: 42±12 yrs; 77.5% male). CMR was suggestive of myocarditis in 8 (20%) patients, of ACM in 29 (72.5%) patients and was normal in 3 (7.5%) patients. Among the 8 patients with CMR diagnosis of myocarditis, 3 (37.5%) patients were fulfilling one major criterion and 2 (25%) patients one minor criterion for the diagnosis of ACM. The diagnosis of myocarditis was confirmed in 5 (62.5%) patients, whereas 3 (37.5%) patients were reclassified, mainly upon biopsy and genetic testing findings, as having ACM (n=2) or myocarditis in ACM (n=1).among the 29 patients with CMR diagnosis of ACM, 13 (44.8%) patients were fulfilling one major criterion and 16 (55.2%) patients one minor criterion for the diagnosis of ACM. The diagnosis of ACM was confirmed in 23 (79.3%) patients, whereas 6 (20.7%) patients were reclassified as having myocarditis (n=5) or myocarditis in ACM (n=1). Among the 3 normal CMRs, a final diagnosis of myocarditis (n=1) and ACM (n=2) was made on the basis of the complete diagnostic workout. Conclusion: CMR can provide valuable knowledge for the differential diagnosis between acute myocarditis and ACM. However, a complete diagnostic work-out including endomyocardial biopsy and genetic testing may reduce the risk of misdiagnosis. B-PO MULTI-MODALITY FUNCTIONAL IMAGING OF ISCHEMIC VENTRICULAR TACHYCARDIA SUBSTRATE: CORRELATION OF I 123 -META-IODOBENZYLGUANIDINE AND 18-FLUORODEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHY WITH HIGH-RESOLUTION ELECTROANATOMIC MAPS IN PATIENTS UNDERGOING VENTRICULAR TACHYCARDIA ABLATION Mohammed Abdulghani, MD, Yousra Ghzally, MD, Hasan Imanli, MD, Wengen Chen, MD, PhD, Mark Smith, PhD, Rama Vunnam, MD, Alejandro Jimenez, MD, Vincent See, MD, Stephen Shorofsky, MD, Vasken Dilsizian, MD and Timm Dickfeld, MD, PhD. University of Maryland, Baltimore, MD, Univeristy of Maryland, Baltimore, MD Background: Denervated and metabolically inactive myocardium detected by 18-Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) has been linked to proarrhymicity of the ischemic Ventricular Tachycardia (VT) substrate. Objective: Compare the functional characteristics of innervation and metabolism with Electroanatomic Maps (EAM) in ischemic patients undergoing VT ablation. Methods: Pre-procedural I123-MIBG and FDG-PET scans were performed in 21 patients with drug-refractory VT and ischemic cardiomyopathy. 3D denervation maps and 3D metabolic scar maps (<50% tracer uptake, respectively) were reconstructed from sequential short axis series and registered with highresolution 3D EAM generated during VT ablation for direct comparison. Results: All 3D denervation/metabolic scar models were successfully reconstructed and registered. MIBG denervated myocardium, metabolic PET scar and EAM (<1.5mV) was 23±8%, 24±12% and 21±8% of total LV (p>0.05). Segmental analysis for MIBG, PET and EAM showed presence of defects inferiorly (100%, 100%, 100% of patients), apically (71, 81%, 67%), anteriorly (5%, 38%, 57%), septally (43%, 29%, 57%) and laterally (33%, 38%, 47%). MIBG/PET had matched defects in inferior, apical, anterior, septal and lateral in 100%, 72%, 12.5%, 44% and 62.5% of patients, respectively. VT channels/ exit sites (n=16) were in 94% (15/16) in an area of denervation OR metabolic scar (bipolar voltage: 0.8±0.9mV). 31% of the VT channels/exit sites were located in myocardium functionally abnormal in metabolism (n=2) or innervation (n=2) alone. 69% (11/16) of the VT channels/exit sites localized to the most severely remodeled myocardium with simultaneous denervation AND metabolic scar (bipolar voltage 0.6±0.3V). Conclusion: Functional VT substrate areas defined by denervation and metabolic scar were similar in size and colocalized well in a segmental analysis. 96% of VT channels/ exit sites are localized in functionally abnormal myocardium with >2/3 of successful ablation sites located in areas of highest functional abnormality (denervated metabolic scar). This suggest a potential role of functional imaging to better understand the pro-arrhythmic VT substrate and identify possible VT ablation targets. B-PO THE UPPER TURNAROUND OF THE REENTRANT CIRCUIT OF LEFT POSTERIOR FASCICULAR VENTRICULAR TACHYCARDIA ASSESSED BY ENTRAINMENT MAPPING Jongmin Hwang, MD, Gi-Byoung Nam, MD, Ungjeong Do, Yu Na Kim, Min Soo Cho, MD, Jun Kim, M.D., Kee-Joon Choi, MD and You-Ho Kim, MD. Seoul Asan Medical Center, Seoul, Korea, Republic of, Asan Medical Center, Cardiology, Department of Internal Medicine, University of Ulsan College of

58 Poster Session V S545 Cardiology, Seoul, Seoul, Korea, Republic of, Pusan National University Hospital, Yangsan, Korea, Republic of, Asan Medical Center, Seoul, Korea, Republic of Background: The major mechanism of the idiopathic left posterior fascicular ventricular tachycardia (LPF-VT) is a reentry. The exact anatomic extent of the reentry circuit has not been defined. There are also debates as to whether the LPF participates in the reentry circuit. Objective: We hypothesized that entrainment technique could be used to delineate the anatomic reentry circuit in patients with LPF-VT. Methods: Ten consecutive LPF-VT patients (pts) treated in our hospital between January 2004 and December 2016 were included. Entrainment pacing was performed at the proximal His-Purkinje system where His or bundle branch potentials were recorded. Results: Average age was 32.2 ± 9.3 years and nine patients were male. 1. During tachycardia, earliest ventricular activation was recorded at the mid to apical septal area. 2. Pacing from the left bundle (LB) area 10-20ms shorter than tachycardia cycle length (TCL) showed concealed entrainment in all pts. The post-pacing interval (PPI, ± 53ms) matched TCL (320.6 ± 55.3ms). Stimulus to QRS interval (290.1 ± 52.7 ms) was 90.5 ± 5.8 % of the TCL. 3. When pacing cycle length was a little bit shortened, entrainment pacing from LB area (performed in 7 pts) showed manifest entrainment (ME). The LPF potential was antidromically captured with PPI minus TCL below 10ms (PPI ± 29.2ms, TCL ± 25.9ms). 4. Pacing from the His bundle area showed ME in 8 pts. The His bundle potential was antidromically captured and the PPI was long (PPI ± 67.7 ms, TCL ± 53.8 ms). Conclusion: Reentry circuit of the LPF-VT may extend from the apical septal to the LB area. The LB area appears to be the entry of the protected slow conduction zone constituting the upper turnaround of the reentry circuit. Direct capture of the LPF showed ME with a PPI nearly identical to the TCL. These findings suggest that the LPF comprises part of the reentry circuit. B-PO LOCAL HIBERNATING MYOCARDIUM USING RUBIDIUM PERFUSION AND 18-FLUORODEOXY POSITRON EMISSION TOMOGRAPHY IN PATIENTS UNDERGOING ISCHEMIC VENTRICULAR TACHYCARDIA ABLATION Mohammed Abdulghani, Yoursa Ghzally, MD, Deya Alkhatib, MD, Mark Smith, PhD, Wengen Chen, MD, PhD, Rama Vunnam, Hasan Imanli, MD, Alejandro Jimenez, MD, Vincent See, Stephen Shorofsky, Vasken Dilsizian and Timm Dickfeld, MD, PhD. University of Maryland, Baltimore, MD Background: Hibernating myocardium has been linked to Ventricular Tachycardia (VT) arrhythmogenesis. Typically, hibernation is only reported if large enough for consideration of revascularization. Therefore, the prevalence of small areas of regional hibernation is not known, but may be critical for ventricular arrhythmogenesis. Objective: Identify prevalence and location of local hibernating myocardium Methods: 24 patients with ischemic, drug-refractory VT underwent pre-procedural Rubidium (Rb)/Fluorodeoxy (FDG) metabolic Positron Emission Tomography (PET). Flownormalized FDG short axis images were quantitatively analyzed in a 757-segment model and classified into normal, mild/ moderate flow reduction, scar and hibernating myocardium. This was co-registered to high-resolution electro-anatomical mapping acquired during VT ablation. Results: Local hibernation could be demonstrated in 100% (24/24) of patients and was either adjacent to PET-defined scar (29%) or myocardium with mild/moderate flow reduction (71%). 2.2±0.9 separate regions of local hibernation were present per patient encompassing each 54±91 segments resulting in a total regional hibernation area of 115±125 out of 757 LV segments In 71% of patients local hibernation was found in two vascular territories (LAD+RCA: 59%; LAD+LCX: 29%; LCX+RCA: 12%). 17% of regional hibernation was found in only one territory (LAD:75%, LCx: 0%, RCA: 25%). 12% of patients (3/24) demonstrated hibernation in all three vascular territories. Bipolar voltage was unable to identify hibernating myocardium (mean voltage 1.78±2.35 mv) as bipolar measurements were equally likely in any of the three bipolar categories (<0.5mV:33%; mV:33% and > 1.5mV:34%). VT channels/exit sites (n=20) were in areas of regional hibernation in 10%. Conclusion: Small areas of locally hibernating myocardium are an unrecognized but present in most/all patients with ischemic cardiomyopathy and refractory VT. Local hibernation is located adjacent to areas of PET defined scar or reduced perfusion. VT circuits/exits sites co-localize in a small but substantial number of VT cases to local hibernation suggesting a potential link of hibernation to proarrhthmogenesis and a potential targets for VT ablation. B-PO ANTEROSEPTAL SUBSTRATE IS ASSOCIATED WITH POOR LONG-TERM OUTCOME AFTER CATHETER ABLATION IN PATIENTS WITH NON-ISCHEMIC DILATED CARDIOMYOPATHY Adrianus P. Wijnmaalen, MD, Micaela Ebert, MD, Marta De Riva Silva, MD, Arash Arya, MD, FHRS, Serge Trines, MD, PHD, Gerhard Hindricks, MD and Katja Zeppenfeld, MD, PhD. Leiden University Medical Center, Leiden, Netherlands, LUMC Leiden, Leiden, Netherlands, Leiden University Medical Cent, Leiden, Netherlands, Heart Center, Leipzig, Germany, Leiden Univ Medical Cent, Leiden, Netherlands, Heart Center - University of Leipzig, Leipzig, Germany Background: Catheter ablation for recurrent ventricular tachycardia (VT) in patients with non-ischemic dilated cardiomyopathy (DCM) can be challenging with inconsistent reports on long term-arrhythmia free survival. Two predominant substrate patterns, an anteroseptal and inferolateral, have been recognized. Objective: To assess the impact of substrate pattern on VT recurrence and mortality after ablation in DCM. Methods: One hundred eight consecutive patients (91(84%) male, 61±13yrs, left ventricular ejection fraction 36±13%) referred for catheter ablation (epicardial approach in 75(69%)) of VT in DCM to 2 tertiary referral centers were included. The predominant scar pattern was determined based on local bipolar (<1.5mV) and/or unipolar (<8.0mV) voltages and bipolar electrogram characteristics recorded during electroanatomical mapping. Results: A predominant anteroseptal substrate was observed in 59 (54%), a predominant posterolateral substrate in 46 (42%) and another substrate pattern in 3 (3%) patients. Noninducibility of any VT was achieved in 47 (43%). During 22 (IQR 10-27) months of follow-up all-cause mortality was 36 (33%) and VT recurred in 47 (44%). After 2 years follow-up an anteroseptal substrate was the only independent predictor for all-cause mortality (HR 3,7 (95%CI )) after adjusting for age, left ventricular ejection fraction, NHYA heartfailure and noniducibility of any VT after ablation. Noninducibility of any VT (HR % (CI )) and an anteroseptal substrate (HR 2.5 (95%CI )) were independently associated with subsequent VT recurrence or mortality.

59 S546 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Conclusion: In DCM an anteroseptal substrate is independently associated with higher all-cause mortality after VT ablation requiring a thorough follow-up of affected patients. Noninducibility and a non-anteroseptal substrate indicate a favorable VT free survival. B-PO PREMATURE VENTRICULAR CONTRACTIONS ORIGINATING FROM THE LEFT VENTRICLE CLOSE TO THE HIS BUNDLE REGION Tomomichi Suzuki, MD, Daizo Ishihara, MD and Shigeki Kobayashi, MD. Inazawa Municipal Hospital, Inazawa, Japan Background: Little is known about the features of ventricular arrhythmias originating from the left ventricle (LV) close to the His bundle (HB) region. Objective: To investigate the electrophysiological characteristics and mechanisms of these ventricular arrhythmias. Methods: Six patients (six men, age 72 ± 4 years) underwent successful catheter ablation of premature ventricular contractions (PVCs) originating from the LV close to the HB region. Results: QRS morphologies of these PVCs were characterized by a left bundle branch block and QS pattern in lead V1 in all, and left superior (n=4) or inferior axis (n=2). In all patients, the earliest ventricular activation sites during PVCs were detected underneath the His potential recording sites within LV and at the lower border of the low voltage zone (<1.0mV) underneath the noncoronary cusp. These sites were considered to be LV underneath the membranous septum. At the sites of earliest activation, high-frequency presystolic potentials (PP) were recorded during PVCs, preceding the QRS by ± 26 ms (range; -10 to -80ms) in all patients. Moreover, the ventricular late diastolic potentials (LDP) were detected during sinus rhythm at these sites, and the morphologies of LDP and PP were identical. The intervals from the ventricular potentials to LDP and PP were equal (363±14 ms, range; 355 to 380ms). Therefore, it was considered that PVCs were induced at the time of intermittent conduction of PP to the ventricular potentials. Radiofrequency delivery at these sites successfully eliminated PVCs in all patients. Conclusion: PP and LDP are critical potentials in PVCs originating from the LV close to the HB region. The mechanism of this PVCs is the intermittent conduction from the localized tissue underneath the left HB region to the interventricular septum. B-PO QUALITY OF LIFE AND PSYCHOLOGICAL WELL-BEING FOLLOWING VENTRICULAR TACHYCARDIA ABLATION Ana Bilanovic, MA, Jane Irvine, PhD, Andreu Porta-Sanchez, MD, Benjamin J. King, MB BS, Paul Angaran, Paul Dorian, MD, FHRS, Abhishek Bhaskaran, MBBS, MD, PhD, Sachin Nayyar, MBBS, MD, PhD, CEPS-A, CCDS, Vivienne A. Ezzat, MBChB, Ann Hill, Sheila Watkins, RN, Zana Mariano, MA, Dibisha Koirala, BA, Shruthi Surendran, BSc, Eugene Downar, MBCHB and Kumaraswamy Nanthakumar, MD. University Health Network, Toronto, ON, Canada, York University, Toronto, ON, Canada, 200 Elizabeth Street, Toronto, ON, Canada, Fremantle Hospital, Perth, Australia, Toronto General Hospital, Toronto, ON, Canada, University of Toronto & St. Michael s Hospital, Toronto, ON, Canada, St. Bartholomew s Hospital Lon, London, United Kingdom, The Toronto Hospital, Pacemaker Clinic, Toronto, ON, Canada, Univ Health Network, Toronto, ON, Canada, St. Michael s Hospital, Toronto, ON, Canada, Univ Health Network - Toronto General Hospital, Toronto, ON, Canada Background: Ventricular tachycardia (VT) is a debilitating, often fatal cardiac event that can lead to impairment in well-being. Implantable cardioverter defibrillators (ICD) are used to treat VT. Having an ICD is protective yet ICD shocks are often associated with diminished quality of life (QoL) and emotional distress. It is crucial to assess if VT ablation can improve patients QoL and emotional distress beyond protective benefits of ICDs. Objective: To examine QoL and psychological well-being over a 6-month follow-up of ICD patients with VT treated with VT ablation compared to ICD patients who had VT but were kept on medical treatment. Methods: Fifty-one case-control ICD patients with VT (Ablation n=29; No Ablation n=22) completed measures of global QoL [SF-36 Mental Health Component Summary (MCS) and Physical Component Summary], depression and anxiety [Hospital Anxiety and Depression Scale (HADS-A)] and trauma [Impact of Events Scale - Revised (IES-R)] at baseline (recruitment/time of ablation) and follow-up. Results: The Ablation group saw improvement between baseline and follow-up in QoL MCS (M = 45.89, SD = vs. M = 50.76, SD = 8.88, p=.002), IES-R Total (M =.95, SD =.75 vs. M =.69, SD =.68, p=.005), Intrusion (M =.94, SD =.83 vs. M =.63, SD =.75, p=.005) and Hyperarousal subscales (M =.95, SD =.88 vs. M =.64, SD =.75, p=.007). The No Ablation group saw improvements in HADS-A (M = 5.05, SD = 4.26 vs. M = 3.67, SD = 3.60, p=.022), IES-R Total (M =.55, SD =.61 vs. M =.30, SD =.42, p=.04), Intrusion (M =.51, SD =.57 vs. M =.27, SD =.38, p=.041) and Hyperarousal (M =.60, SD =.67 vs. M =.27, SD =.54, p=.016) but not QoL (M = vs ). Between-group regression analyses showed no significant differences. Conclusion: ICD patients with VT who had VT ablation improved in mental health QoL and emotional distress. ICD patients who had VT but no ablation saw no improvement in mental health QoL. This is encouraging as ablation patients represent a sicker group of ICD patients who might be expected to exhibit deteriorating QoL rather than improvement. As no between-group differences were found, further study is needed to better understand QoL benefits of VT ablation in the ablation subgroup. B-PO OUTCOME OF CATHETER ABLATION WITH AND WITHOUT DRUG PROVOCATION IN PATIENTS WITH BRUGADA SYNDROME: A MULTI-CENTER EXPERIENCE Andrea Natale, MD, FHRS, Sanghamitra Mohanty, MD, FHRS, Jason Bradfield, MD, FHRS, Antonio Dello Russo, MD, PhD, Amin Al-Ahmad, MD, FHRS, CCDS, J. David Burkhardt, MD, FHRS, Michela Casella, Ghaliah Al Mohani, MD, PHD, FHRS, Pasquale Santangeli, MD, Chintan G. Trivedi, MD, MPH, FHRS, Carola Gianni, MD, PhD, Roderick Tung, MD, FHRS, Xianfeng Du, MD, Domenico Giovanni Della Rocca, MD, Luigi Di Biase, MD, PhD, FHRS and Kalyanam Shivkumar, MD, PhD, FHRS. Texas Cardiac Arrhythmia Institute at St. David s Medical Center, Austin, TX, St. David s Medical Center, Austin, TX, Univ of California at Los Angeles, Cardiac Arrhythmia Ctr, Manhattan Beach, CA, Centro Cardiologico, Milan, Italy, Texas Cardiac Arrhythmia Institute, Austin, TX, National Heart Center/Royal Hospital, Muscat, Oman, University of Pennsylvania, Philadelphia, PA, Texas Cardiac Arrhythmia Institute, Electrophysiology, Austin, TX, University of Chicago, Chicago, IL, Albert Einstein College of Medicine at Montefiore Hospital, NY, NY, Texas Cardiac Arrhythmia Institute, St. David s Medical Center, Austin, TX, Albert Einstein College of Medicine

60 Poster Session V S547 at Montefiore Hospital, New York, NY, UCLA Health System, Los Angeles, CA Background: Sodium-channel blocking agents are used to unmask the typical ECG features and arrhythmogenic substrate in patients with Brugada Syndrome (BrS) with the reported success rate of % with the pharmacological challenge. Objective: We present the procedure outcome in patients with BrS undergoing catheter ablation with and without drug provocation. Methods: This multi-center series included 16 patients receiving catheter ablation for BrS, of which 10 underwent no drug provocation (no-drug) and 6 received procainamide-challenge (Proc). Endo- and epicardial electroanatomical mapping and ablations were performed using 3-D mapping system. Complete elimination of abnormal electrograms with subsequent noninducibility of ventricular arrhythmia was the ablation endpoint. All patients were followed up with quarterly device interrogation; episode(s) of ventricular fibrillation or tachycardia (VF/VT) was considered as the long-term end point. Results: The mean age was 40.5 ± 11.6 and 46.0 ± 15.5 years and 100% vs 90% cases were male in the Proc- vs no-drug group respectively. Family history of sudden death was reported in 1 patient. Brugada-specific ECG was detected in all except 2 cases at baseline. Fifteen (94%) patients had implantable cardioverter-defibrillator (ICD); 1/15 had VT storms and all except 1 suffered from frequent shocks prior to ablation. Fluoro time was comparable between the groups (18.1 ± 0.14 vs 15.9 ± 8.1 min in no-drug vs Proc group). Low voltage endo- and/ or epicardial areas in the right ventricle were detected in all with or without drug provocation. At the end of the procedure, normalization of the ECG and non-inducibility of VT/VF were demonstrated in all. No complication in the immediate postablation period was reported. At 1-year follow-up, 3 patients (50%) from the Proc-group had suffered from ICD shocks or VF recurrence and 2 of the 3 remained stable on quinidine. In the no-drug group, 1/10 (10%) patient had recurrence from RV apical PACs; others remained arrhythmia-free. Conclusion: Our findings suggest that catheter ablation without drug-provocation was successful in achieving high rate of freedom from VT/VF, in patients with Brugada Syndrome B-PO ABLATION OF VENTRICULAR TACHYCARDIA IN PATIENTS WITH STRUCTURAL HEART DISEASE AND ELECTRICAL STORM Shibu Mathew, MD, Tilmann Maurer, Christine Lemes, Bruno Reismann, Francesco Santoro, Christian Heeger, Andreas Rillig, MD, Andreas Metzner, Karl-Heinz Kuck and Feifan Ouyang. St. George Asklepios Klinik, Hamburg, Germany, Tilmann Maurer, Hamburg, Germany, AK St Georg, Germany, Bruno Reismann, Hamburg, Germany, Francesco Santoro, Hamburg, Germany, Christian Heeger, Hamburg, Germany, Charité University Hospital of Berlin, Berlin, Germany, Andreas Metzner, Hamburg, Côte D Ivoire, Feifan Ouyang, Hamburg, Germany Background: Electrical Storm is a life threatening situation in patients (pts) with structural heart disease. Interventional treatment options are sparse and may result in high mortality and complications. Objective: But still there are only limited information and therefore this study analysed outcome and safety in Endocardialand Epicardial Ablation of Ventricular Arryhtmia (VA) in this patient population. Methods: In 187 patients (pts; 170 male; 64±13years) with Electrical Storm and Structural Heart Disease (SHD) catheter ablation of Ventricular Arryhthmia (VA) was performed in 229 procedures and retrospectively analysed. Results: The underlying heart diseases were Ischemic Heart Disease (IHD) in 121/187 pts (64,7%), Dilative Cardiomyopathy (DCM) in 48/187 pts (25,7%) and different entities of cardiomyopathy in 18/187 pts (9,6%). Mean LVF was 33±13 and 168/187 pts (89,8%) presented with an ICD at time of procedure. A history of coronary artery bypass graft (CABG) was presented in 43/121 pts (35,5%). VT Procedure was performed despite severe Infection or Sepsis due to electrical and hämodynamical instability in 3/187 pts (1,6%). General anesthesia was necessary prior to ablation in 32/187 pts (17,1%). An extracorporeal membrane oxygen system (ECMO) was implanted in 2/187 pts prior to ablation and in 2/187 pts during ablation, whereas one procedure was performed under Heart Mate II assistance. In 47/229 proc. (20,5%) a combined endo-/epicardial proc was peformed. In pts with IHD in 109/145 proc (75,2%) acute success and in 21/145 proc (14,5%) partial success could be achieved, whereas proc. without success were 15/145 (10,3%). Acute, partial and no success were in 45/60 (75%), 3/60 (5%) and 12/60 (20%) procedures in pts with DCM respectively. Conclusion: Catheter ablation of VA in pts with electrical storm is an effective treatment option in this patient population. B-PO EPICARDIAL CRYOABLATION AT THE TIME OF LVAD IMPLANTATION MAY REDUCE IMPLANTABLE CARDIOVERTER DEFIBRILLATOR SHOCKS POST LVAD Adam Oesterle, MD, Michael Raiman, CEPS, Erin E. Flatley, BSN, MSN, NP, Andrew D. Beaser, MD, Valluvan Jeevanandam, MD, Liviu Klein, MD, MS, Takeyoshi Ota, Georg Wieselthaler, Nir Uriel, MD, Roderick Tung, MD, FHRS and Joshua D. Moss, MD, FHRS. University of California San Francisco, San Francisco, CA, Abbott, South Elgin, IL, University of Chicago Medical Center, Chicago, IL, University of Chicago, Chicago, IL, University of California, Los Angeles, San Francisco, CA, UCSF, Burlingame, CA Background: Ventricular arrhythmias (VA) are common after LVAD implant and are associated with increased morbidity and mortality. Objective: To determine the efficacy and safety of intraoperative epicardial ablation at the time of LVAD implantation for treatment and prevention of post-operative VA. Methods: Patients with a history of sustained VA undergoing LVAD implant were approached for open-chest intraoperative epicardial voltage mapping and empiric ablation targeting fractionated signals and late potentials. Clinical outcomes were assessed prospectively. Results: From 2016 to 2017, 5 patients underwent intraoperative epicardial mapping and cryoablation at 2 centers (Figure). The median age was 70 years, median ejection fraction 20%, and 3 patients were receiving the LVAD as destination therapy. The etiology of cardiomyopathy was ischemic in 3 patients. All patients had at least 1 ICD shock, and 4 of the 5 had VA storm prior to LVAD implantation. A HeartMate 2 device was implanted in 2 patients, HeartMate 3 in 1 patient, and a HeartWare HVAD in 2 patients. Median post-operative follow up was 132 (IQR ) days. Despite epicardial ablation, 4 of the 5 patients had sustained VA during post-operative followup: 2 required ICD shocks, and 2 had successful ATP therapy. There were no complications of epicardial mapping or ablation. During follow-up, there was 1 ischemic stroke and no LVAD thromboses or deaths. Conclusion: Epicardial ablation at the time of LVAD implantation is safe and may reduce VA burden or need for ICD shocks post-operatively. Patients with history of ICD shocks and VA storm remain at high risk for VA after LVAD implant.

61 S548 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO ARTERIAL DAMAGE DURING ANTERIOR APPROACH FOR PERICARDIAL ACCESS: AN UNRECOGNIZED AND LIFE THREATENING COMPLICATION Luis C. Saenz Morales, MD, Carlos A. Tapias, Cristiano F. Pisani, MD, Roderick Tung, MD, FHRS, Mauricio Scanavacca, MD and Fermin C. Garcia, MD. Cardioinfantil Foundation, Cardiac Institute, Bogota, Colombia, Bogota, Colombia, InCor, Sao Paulo, Brazil, University of Chicago, Chicago, IL, Instituto Do Coração, Sao Paulo, SP, Brazil, Hospital of the University of Pennsylvania, Philadelphia, PA Background: Anterior pericardial puncture (APP) to avoid subdiaphragmatic visceral and vascular damage has emerged as a safer alternative for pericardial access. Objective: To report the presentation and management of three cases of vascular bleeding associated with this technique. Methods: N/A Results: Three male pts. (38 y.o with ARVD, 61 y.o with Chagasic CMP, 46 y.o with prior myocarditis) underwent APP for epicardial VT mapping/ablation. The pericardial access was performed in LL fluoroscopic view by advancing the Tuohy needle bellow the sternum and over the diaphragm aimed to the anterior RV. Finally, a guidewire and deflectable sheath were introduced inside the pericardium. In the first case, pulsatile blood was seen while advancing the needle. Arteriography of the LIMA demonstrated injury of the superior epigastric artery (SEA). A coil was advanced through the LIMA and delivered proximal to that level to stop the bleeding (Figure). In the other 2 cases, small but continuous bleeding on the skin around the pericardial sheaths was observed. Once the procedure was completed the steerable sheath was exchanged over a wire and a pig tail placed in the pericardial space with rapid presentation of hypotension and tamponade. Both patients underwent cardiac surgery with no identification of cardiac perforation. In both cases injury of the SEA was diagnosed and ligation of the LIMA was required to control bleeding (Figure). The patients were discharged and no VT recurrences have been detected during a follow-up. Conclusion: Injury of the superior epigastric artery or LIMA is a risk of APP. Urgent arteriography of the LIMA with coil embolization or surgical ligation are the therapies of choice. B-PO CHARACTERISTICS AND ACUTE OUTCOME OF PERIAORTIC VENTRICULAR TACHYCARDIA TREATED BY CATHETER ABLATION Benjamin Schaeffer, MD, Ammar M. Killu, MBBS, Shin-ichi Tanigawa, Tomofumi Nakamura, MD, PhD, Qi Zheng, MD, Roy M. John, MD, PhD, FHRS, CCDS, William G. Stevenson, MD, FHRS and Usha B. Tedrow, MD, MS, FHRS. Brigham and Women s Hospital, Boston, MA, Mayo Clinic, Rochester, MN, Brookline, MA, Brigham and Women s Hospital, Cambridge, NY, Vanderbilt University Medical Center, Nashville, TN, Vanderbilt University Heart and Vascular Center, Nashville, TN, Brigham and Women s Hospital, Cardiology, Boston, MA Background: Ventricular arrhythmia (VA) from the periaortic region are encountered in patients with and without structural heart disease (SHD) but data regarding catheter ablation (CA) characteristics in patients with differing underlying substrates is limited. Objective: To evaluate characteristics and acute outcome of CA for periaortic VA in patients (pts) with and without SHD. Methods: We analyzed all CA procedures for periaortic origin PVCs or VT from 01/ /2017. Patients were grouped according to the absence of SHD (NSHD; n=51) or presence of SHD with obstructive CAD (ICMP n=36) non-ischemic ethology (NICMP; n=115). Results: Of 866 VA ablations, a total of 222 procedures in 202 pts were for periaortic VA. Pts with SHD were more often male, older with lower EF and higher proportion of ICD/CRT implant than NSHD group (table). Isolated PVC were targeted more frequently in the NSHD group, and successful CA site was more frequently located above the aortic valve (36%), though 11 and 15% of the ICMP and NICMP pts respectively required CA above the valve as well. SHD pts had more VT morphologies targeted and NICMP pts more often received advanced techniques (transcoronary ethanol, needle, simultaneous unipolar). All groups had similar rates of repeat procedures (8-19% of cases). However, there was a trend towards higher rate of complications and a lower acute success rates in pts with SHD (table). Conclusion: CA of periaortic VAs remains challenging both in presence and absence of SHD with frequent need of advanced ablation and mapping techniques and possibly increased risk among pts with SHD and NICMP in particular.

62 Poster Session V S549 table; * in some procedures several successful sites above / below valve due to multiple morphologie NSHD N=51 ICMP N=36 NICMP N=115 Age (years) 56±15 72±9 62±12 < Male (n,%) 36 (71) 32 (89) 101 (88) 0.01 EF (%) 58±6 38±14 39±12 < ICD/CRT (n,%) 10 (19) 25 (70) 75 (65) < Only PVCs present (n,%) PVC morphologies targeted (n) VT morphologies targeted (n) Repeat procedure (n,%) VT cycle length (ms) Advanced ablation technique required Successful CA above valve (n,%)* Successful CA below valve (n,%)* Acute success (n,%) Partial success (n,%) Failure (n,%) not tested (n,%) Major complications, all (n,%) Tamponade Femoral/Groin AV-Block B-PO (79) 1.2± ±1.5 6 (12) 380±95 11 (31) 1± ±1.9 3 (8) 403± (54) 1.3± ± (19) 357±90 P < (2) 1 (3) 16 (14) (36) 41 (64) 41 (72) 12 (21) 4 (7) 0 1 (2) (11) 34 (89) 19 (51) 9 (24) 1 (3) 8 (22) 2 (5) (15) 115 (85) 75 (59) 34 (27) 3 (2) 16 (12) 13 (10) PREDICTORS OF VENTRICULAR TACHYARRHYTHMIA RECURRENCE IN PATIENTS WITH IDIOPATHIC VENTRICULAR TACHYARRHYTHMIA UNDERGOING OUTFLOW TRACT RADIOFREQUENCY CATHETER ABLATION Zahra Azizi, MD, Yaariv Khaykin, MD, FHRS, Pouria Alipour, Sereena Nath, Patrick Mallany, Nikhil Nath, Alona Avoulov, Stacey Morris, Jamie Forman, Mehras Motamed, Paul Ritvo, Alfredo A. Pantano, MD and Atul Verma, MD, FHRS. Southlake Regional Health Centre, Newmarket, ON, Canada, Southlake Regional Health Center / Heart Rhythm Research, Newmarket, ON, Canada, Southlake Health Regional Centre, Aurora, ON, Canada, Southlake Regional Health Centre, Toronto, ON, Canada Background: Idiopathic ventricular tachyarrhythmias in patients without structural heart disease frequently originates from the right and left ventricular outflow tracts. Objective: This study was conducted to create a predictive model for recurrence of VT in patients who underwent outflow tract VT ablation. Methods: Data for 132 patients (64(49%)male with mean age of 54+/-15 years) who underwent outflow tract VT ablation, between were collected. Patients who had history of Ischemic cardiomyopathy and ICD were excluded from the study. Overall 88(67%) patients underwent RVOT ablation while 28(21%) and 16(12%) underwent LVOT and LVOT+RVOT ablation respectively. ECG, and ambulatory monitoring were collected at 1, 3, 6, and 12 months post ablation. Univariate and multivariate analyses were used to determine the likelihood of arrhythmia recurrence post ablation. Results: 86 (65%) patients had acute procedural success (no clinical or non clinical arrhythmia inducible at the end of the procedure) and 43(32.6%) patients had VT recurrence during follow up. Overall freedom from VT at 12 months was 67%, while freedom from RVOT, LVOT and RVOT/LVOT VT was 71%, 69%, and 48% respectively. Univariate COX regression analysis showed history of dilated cardiomyopathy (DCM, HR=3.5, p=0.001), lack of retrograde access to the LVOT (having to use transseptal access, HR=6.9, p=0.002), history of having failed flecainide (HR=3.3, P=0.002), and history of electrical storm (HR=39, P=0.002) to be significant risk factors for VT recurrence. RVOT origin of VT (HR=0.52, P=0.04), acute success (HR=0.38, P=0.003), and using isoproterenol to induce VT during ablation (HR=0.48, P=0.03) were protective from VT recurrence. History of DCM (HR=3.8, P=0.006), electrical storm (HR=21, P=0.01), history of having failed flecainide (HR=3.35, p=0.01), and acute success (HR=0.45, P=0.03) were still significant in the multivariate model. Conclusion: Patients with Outflow Tract Idiopathic VT with history of DCM, those who had previously failed flecainide and patients with history of electrical storm have higher risk of arrhythmia recurrence, while those who have acute success post ablation have lower risk of VT recurrence. B-PO OUTCOMES OF URGENT STELLATE GANGLION BLOCK FOR MEDICALLY REFRACTORY VENTRICULAR ARRHYTHMIA STORM Ying Tian, MD, PhD, Erica D. Wittwer, MD, PhD, Suraj Kapa, MD, FHRS, Christopher J. McLeod, MD, PhD, FHRS, Peter A. Noseworthy, MD, Siva K. Mulpuru, BS, MB, MBBS, MD, FHRS, CCDS, Abhishek Deshmukh, MD, Hon-Chi Lee, MD, PHD, Michael J. Ackerman, MD, PhD, Samuel J. Asirvatham, MD, FHRS, Thomas M. Munger, MD, FHRS, Paul A. Friedman, FHRS and Yong-Mei Cha, MD, FHRS. Mayo Clinic, Rochester, MN, Mayo Clinic, Tucson, AZ, Mayo Clinic, Dept of Internal Medicine, Rochester, MN Background: Percutaneous stellate ganglion block (SGB) has been used to control electrical storm (ES) associated with drug refractory ventricular arrhythmia (VA) in case reports. Its acute effect on VA control and mid-term outcomes have not been well studied. Objective: To assess the short-term and long-term efficacy of ultrasound guided SGB in patients presented with ES. Methods: Urgent SGB, guided by bedside ultrasound, was performed in patients presented with ES ( 3 episodes of sustained VA within 24 hours) refractory to medical therapy. Eight ml of 0.5% bupivacaine was injected at neck with good local anesthetic spread in the vicinity of the ganglion for left or bilateral SGB. The acute and long-term outcomes, and procedure related complications were studied. Results: Seventeen patients (age 57±12 years, 71% male, LVEF 33±18%) underwent left (n=4) or bilateral (n=13) SGB. Seven patients (41%) had HeartMate II left ventricular assist device (LVAD) in place and 8 patients (47%) had extracorporeal membrane oxygenation (ECMO) for hemodynamic support during ES. Underlying substrate among patients with VA was ischemic (N=10, 59%, 6 with acute myocardial infarction) and nonischemic cardiomyopathy (N=7, 41%). Five patients had monomorphic VT, while 12 had VF or polymorphic VT. There were no procedure related complications. Within 24 hours after SGB, VA was eliminated in 10 patients (59%) and reduced in 4 patients (23%). There was no difference in controlling ES between bilateral SGB and left SGB (11/14 bilateral SBG, 3/4 left SGB, P=1.00). Three patients underwent catheter ablation for VA following SGB. Polymorphic VT or VF, compared to monomorphic VT, was associated with a greater effect of ES control (100% vs 40%, P=0.015). Four patients died in-hospital of heart failure (Two with monomorphic VT and 2 with VF or polymorphic VT). After an average follow-up 15±8 months, none of 13 survivors died and 9 (69%) of them were free from recurrent VA or ICD therapy. Conclusion: Urgent SGB guided by bedside ultrasound is an effective therapy to mitigate ES, especially VF or polymorphic

63 S550 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 VT. Patients who have survived from ES appear to have a good mid-term outcome without recurrent VA or ES. B-PO INTRACARDIAC ELECTROGRAMS: DISSECTING THE CHARACTERISTICS OF VENTRICULAR TACHYCARDIAS OF EPICARDIAL ORIGIN IN PATIENTS WITH IMPLANTABLE CARDIOVERTER DEFIBRILLATOR Iwanari Kawamura, MD, Seiji Fukamizu, MD, Satoshi Miyazawa, MD, Rintaro Hojo, Harumizu Sakurada, MD, PhD and Masayasu Hiraoka, MD, PhD, FHRS. Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan, Tokyo, Japan, Tokyo Metropolitan Hioo Hospital, Tokya, Japan, Tokyo Medical and Dental University, Tokyo, Japan Background: While characteristic waveforms of 12-lead electrocardiogram have been reported to predict the epicardial origin of ventricular tachycardia (VT), it has not been fully examined whether ventricular intracardiac electrograms (VEGMs) recorded from implantable cardioverter defibrillator (ICD) via telemetry can determine the origin of VT or not. Objective: To investigate the VEGM characteristics of VT originating from the epicardia. Methods: Forty-two patients with ICD underwent VT ablation following appropriate therapy from January, 2013 to September, Seventeen (18 VTs) of 42 patients were recorded intracardiac VEGM of the induced VTs which were confirmed their sites of origin during VT study. The characteristics of 18 VTs were evaluated using the far-field and near-field VEGM recorded via telemetry. Results: Six of 18 VTs were found the focus on the epicardial site (epi group) and 12 VTs were on the endocardium (endo group). VTs of the epi group had longer VEGM duration in farfield EGM than that of the endo group (epi group; 235±64ms vs endo group; 151±42ms, p<0.01) and the duration from the onset to the peak of VEGM was also longer than the endo group (epi group; 138±56ms vs endo group; 70±23ms, p<0.01). Receiver operating characteristic curve analysis of far-field VEGM duration revealed that the area under the curve was 0.903, with a cut-off value of 212ms; sensitivity and specificity were 66.7% and 100%, respectively. There was no difference in the V wave duration in tip-ring EGM between two groups (epi group; 113±29ms vs endo group; 100±17ms, p=0.230). Conclusion: Evaluation of intracardiac VEGM before the VT ablation may be helpful to predict the epicardial origin of VT in patients with ICD. B-PO PREDICTION OF VENTRICULAR TACHYARRHYTHMIAS BY INTRACARDIAC ACTIVATION RECOVERY INTERVAL VARIABILITY Bradley Porter, MBChB, Martin J. Bishop, PhD, Justin Gould, Baldeep Singh Sidhu, Benjamin J. Sieniewicz, MBChB, Christopher A. Rinaldi, MD, FHRS, Peter Taggart and Jaswinder Gill, MD FRCP. King s College London, London, United Kingdom, King`s College London, London, United Kingdom, St. Thomas Hospital, Cardiac Dept, London, United Kingdom, The Hatter Cardiovascular Institute, London, United Kingdom, Guys and St. Thomas Hospital, London, United Kingdom Background: Enhanced beat-to-beat variability of repolarization (BVR) is strongly linked to arrhythmogenesis and is largely due to variation in ventricular action potential duration (APD). Previous studies in humans have relied on QT interval measurements; however, a direct relationship between beat-tobeat variability of APD and arrhythmogenesis in humans has yet to be demonstrated. Objective: To explore BVR at the level of the ventricular action potential. Methods: 34 patients with heart failure and implanted CRT-D devices were studied. Activation recovery intervals (ARI) as a surrogate for APD were recorded from the left ventricular epicardial lead while pacing from the right ventricular lead to maintain constant cycle length (Figure 1A). Results: After mean follow-up of 18±10 months, 5 patients of 34 sustained VT/VF and received appropriate ICD therapies (Anti-Tachycardia Pacing or shock therapy). Patients receiving appropriate ICD therapy had significantly higher ARI variability (ARIV) than those without arrhythmia (5.4±2.6 ms vs. 3.5±1.7 ms, p=0.03). The Kaplan-Meier survival analysis demonstrated that the time until first appropriate therapy for VT/VF was significantly shorter in the top quartile for ARIV (p=0.02) (Figure 1B). ARIV was the only significant predictor of appropriate therapy for VT/VF in the multivariate Cox model after adjusting for significant clinical covariates (age, EF) (Figure 1C). Conclusion: Increased beat-to-beat variation in left ventricular APD (measured as ARI) is associated with an increased risk of VT/VF in patients with heart failure. Results support the possibility of BVR as an adjunct to risk stratification. B-PO RATE OF HEART RATE REDUCTION AFTER EXERCISE IS A USEFUL TOOL FOR RISK STRATIFICATION IN CATECHOLAMINERGIC POLYMORPHIC VENTRICULAR TACHYCARDIA Krystien V.V. Lieve, MD, Veronica Dusi, J. Martijn Bos, Conor M. Lane, MBChB, Aurora Djupsjöbacka, Thomas M. Roston, MD, Isabelle Denjoy, MD, Christian van der Werf, MD, Nynke Hofman, MSc, Tomas Robyns, MD, Maarten P. van den Berg, Janneke A.E. Kammeraad, Michael Tanck, Frederic Sacher, MD, Peter J. Schwartz, MD, Minoru Horie, MD, PhD, Vincent Probst, MD, Antoine Leenhardt, MD, Shubhayan Sanatani, MD, FHRS, CCDS, Jason D. Roberts, Heikki Swan, MD, PhD, Michael J. Ackerman, MD, PhD and Arthur A. M. Wilde, MD, PhD. University of Amsterdam - Academic Medical Center, Amsterdam, Netherlands, Amsterdam, Netherlands, Fondazione IRCCS Policlinico San Matteo and University of Pavia, Milano, Italy, Mayo Clinic, MN, Rochester, MN, Helsinki University Hospital, Helsinki, Finland, Department of Medicine, Vancouver, BC, Canada, Hopital Lariboisiere, Paris, France, Academic Medical Center, Amsterdam, Netherlands, University of Leuven, Leuven, Belgium, Universitair Medisch Centrum Groningen, Groningen, Netherlands, Sophia Children s Hospital, Erasmus Medical Centre, Rotterdam, Netherlands, University

64 Poster Session V S551 of Amsterdam - Academic Medical Center, Netherlands, LIRYC Institute/ Bordeaux University Hospital, Bordeaux, France, Center for Cardiac Arrhythmias of Genetic Origin, Milan, Italy, Shiga University of Medical Sciences, Japan, CHU De Nantes, Nantes, France, Bichat University Hospital, France, France, Children s Heart Centre, Vancouver, BC, Canada, Western University in London, London, ON, Canada, Mayo Clinic, Rochester, MN, Univ of Amsterdam - Academic Medical Center, Amsterdam, Netherlands Background: Risk stratification in catecholaminergic polymorphic ventricular tachycardia (CPVT) is ill defined. Heart rate (HR) reduction after exercise is regulated by autonomic reflexes and may predict the probability of symptoms in CPVT patients. Objective: To evaluate if HR reduction one minute after maximal exercise on the exercise test (xtest) can identify CPVT patients at increased risk of symptoms prior to diagnosis and treatment. Methods: In this retrospective observational study, we included patients 65 years with an xtest without antiarrhythmic drugs who attained 80% of the predicted maximal HR. HR reduction in the recovery phase was calculated as the difference in HR at maximal exercise and at one minute in the recovery phase (ΔHR1 ). Logistic regression was used to calculate odds ratios. Results: We analyzed 152 patients (median age 36 years [interquartile range, 19-47], 40% male, 95% RYR2 mutation carrier, 24% proband). Prior to diagnosis, 53/152 patients (34.9%) had experienced an arrhythmic syncope or aborted cardiac arrest. Pre-xtest HR and maximal HR were equal among asymptomatic and symptomatic patients (Figure). Symptomatic patients had a larger ΔHR1 after maximal exercise (43 ± 24 vs. 27 ± 11 bpm, P<0.001, Figure). Corrected for age and gender, patients in the upper quartile for ΔHR1 had an odds ratio of 6.1 (95% CI ) of being symptomatic before diagnosis (P<0.001, area under the curve, 0.74). Conclusion: Symptomatic CPVT patients are more likely to exhibit a larger HR reduction following exercise. Both rapid activation of vagal reflexes and sympathetic deactivation are implicated in HR reduction and may contribute to risk stratification. Okayama University, Okayama City, Japan, Okayama University, Cardiology, Okayama, Japan Background: Prognostic significance of programmed electrical stimulation (PES) has long been debated in Brugada syndrome (BrS). Pooled data analysis showed that PES could identify the high-risk patients. However, PES is an invasive examination and appropriate patient selection should be required, especially in asymptomatic patients. Recently we have reported that fragmented QRS (multiple spikes within QRS complex, fqrs) and long Tpe interval (interval between peak of T wave to end of T wave) are common risk factors for future ventricular fibrillation (VF) events in both asymptomatic and symptomatic patients with BrS. Objective: To establish the indication of PES for asymptomatic patients with BrS, we evaluated the prognostic significance of PES based on abnormal ECG markers. Methods: The subjects were comprised of 125 asymptomatic patients with BrS (age: 46±12 years). We evaluated existence of fqrs and Tpe interval (lead V2) for abnormal ECG markers. PES was performed at 2 sites of right ventricle (RV) with up to 3 extrastimuli and 180ms of minimum coupling interval in all patients. Results: fqrs and long Tpe interval ( 100ms) were observed in 66 (53%) and 37 patients (30%), respectively. VF was induced by PES in 60 asymptomatic patients (48%). During follow-up (115±70 months), 10 patients (8%) experienced VF events. fqrs, long Tpe interval and PES-induced VF were associated with future VF events (hazard ratio [HR], fqrs: 5.9 [confidence interval, CI: , p<0.05], Tpe 100ms: 3.8 [CI: , p<0.05], VF induction: [CI , p<0.01]). Induction site and coupling interval of extrastimuli were not associated with VF events but PES-induced VF by one extrstimulus was a risk factor for VF. If patients had fqrs and/or Tpe 100ms, PESinduced VF was significantly associated with VF events during follow-up (event ratio at 12 years; no abnormal ECG markers: 0%, no VF induction: 3%, PES-induced VF and one of the ECG markers: 20%, PES-induced VF and both ECG markers: 47%, p<0.001). Conclusion: PES is not recommended to patients who did not have ECG abnormalities. If patients have fqrs and/or long Tpe interval, PES should be recommended to identify the high-risk patients. ICD implantation is recommended to patients having both ECG abnormalities and PES-induced VF. B-PO B-PO INDICATION AND PROGNOSTIC SIGNIFICANCE OF PROGRAMMED ELECTRICAL STIMULATION IN ASYMPTOMATIC PATIENTS WITH BRUGADA SYNDROME Hiroshi Morita, MD, PhD, Atsuyuki Watanabe, MD, PhD, Koji Nakagawa, MD, PhD, Masakazu Miyamoto, MD, Yoshimasa Morimoto, MD, Satoshi Kawada, MD, Nobuhiro Nishii, MD and Hiroshi Ito, MD, PhD. Okayama University Graduate School of Medicine, Cardiovascular Therapeutics, Okayama, Japan, Cardiology, Okayama, Japan, Department of Cardiovascular Medicine, Okayama University Graduate School of Med, Okayama, Japan, Okayama University Graduate School of Medicine, Cardiology, Okayama, Japan, Okayama City, Japan, IS THE STRUGGLE AGAINST TONGUE SWALLOWING PREVENTING RESUSCITATION OF ATHLETES WITH CARDIAC ARREST? Dana Viskin, Raphael Rosso, Ofer Havakuk, Lior Yankelson and Sami Viskin. Tel Aviv Sourasky Medical Center, Tel Aviv, Israel Background: The impact of inadequate resuscitation of athletes with cardiac arrest (CA) during competition is larger than commonly appreciated. We recently published that the main obstacle to an appropriate bystander response during athletes CA is a widespread myth: that tongue swallowing during loss of consciousness must be relieved to prevent asphyxia. We continuously search the internet for videos showing CA events of athletes and present updated data for 32 cases. Objective: To evaluate the first-response to a witnessed collapse during competition. Methods: We searched the internet for CA events of athletes caught on video and studied the appropriateness of the response of fellow athletes and team medical-personnel. Results: We now have 32 videos, from 20 countries, recorded during , showing athletes with CA (n=25) or transient loss of consciousness prompting resuscitation maneuvers (n=7).

65 S552 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 All but one were male, aged 25 ±3.9 years; 21 cases (66%) involved soccer players collapsing midgame. In 28 videos, the first intervention was visible and in 19 (68%) it was an attempt to prevent tongue swallowing (Figure 1). Chest compressions were applied to only 38% of athletes and were started after 58 ±27 seconds. Only 7% of players with CA were treated with an external automatic defibrillator. Videos of the events will be presented. Conclusion: According to videos of athletes collapsing with CA, prevention of tongue swallowing takes precedence over chest compressions. Exposure of the tongue swallowing myth may save lives. B-PO A NOVEL PREDICTION MODEL FOR RISK STRATIFICATION IN PATIENTS WITH A TYPE 1 BRUGADA ECG PATTERN Muthiah Subramanian, MD, Mukund Prabhu, MD, Maneesh Rai, MS Harikrishnan, Saritha Sekhar, Praveen Pai and K. U. Natarajan, MD. Amrita Institute of Medical Sciences, Ernakulam, India, Kasturba Medical College, Mangaluru, India, Amrita Institute Of Medical Sciences, Kochi, India Background: Risk stratification in Brugada syndrome remains a controversial and unresolved clinical problem, especially in asymptomatic patients with a type 1 ECG pattern. Objective: The purpose of this study is to derive and validate a prediction model based on clinical and ECG parameters to effectively identify patients with a type 1 ECG pattern who are at high risk of major arrhythmic events (MAE) during follow-up. Methods: This study analysed data from 103 consecutive patients with Brugada Type 1 ECG pattern and no history of previous cardiac arrest. The prediction model was derived using logistic regression with MAE as the primary outcome, and patient demographic and electrocardiographic parameters as potential predictor variables. The model was externally validated in an independent cohort of 26 patients. Results: The final model (Brugada Risk Stratification [BRS] score) consisted of 4 independent predictors (1 point each) of MAE during follow-up (median 85.3 months): spontaneous type 1 pattern, QRS fragments in inferior leads > 3, S wave upslope duration ratio > 0.8, and T peak - T end > 100 ms. The BRS score (AUC=0.95,95% CI ) stratifies patients with a type 1 ECG pattern into low (BRS score < 2) and high (BRS score > 3) risk classes, with a class specific risk of MAE of 0-1.1% and % across the derivation and validation cohorts, respectively. Conclusion: The BRS score is a simple bed-side tool with high predictive accuracy, for risk stratification of patients with a Brugada Type 1 ECG pattern. Prospective validation of the prediction model is necessary before this score can be implemented in clinical practice. B-PO IMPACT OF VENTRICULAR ARRHYTHMIA ON THE PROGNOSIS OF HEART FAILURE PATIENT Shinya Yamada, MD, Hitoshi Suzuki, MD, Masashi Kamioka, Takashi Kaneshiro and Yasuchika Takeishi. Fukushima Medical University, Fukushima, Japan, University of Tsukuba, Tukuba, Japan Background: The parameters obtained from Holter monitoring provide useful information on the clinical management of various cardiac diseases. Objective: The present study aimed to clarify the impact of premature ventricular complex (PVC) and non-sustained ventricular tachycardia (NSVT) in risk stratification of heart failure (HF) patients. Methods: We studied 435 HF patients (271 males, mean age 65 years). All patients were hospitalized for the treatment of acute decompensated HF for the first time. After optimal medications, 24-hour Holter monitoring was performed. The clinical characteristics and outcomes of HF patients were investigated. Results: During the follow-up (3.4±2.1 years), there were 120 (27.5%) cardiac events (re-hospitalization due to worsening HF, cardiac death or sudden death). The patients with cardiac events had higher PVC burden and prevalence of NSVT (>3 beats) compared to the patients without cardiac events (PVC burden, 2.8±6.7%/day vs. 1.2±4.0%/day, P=0.002; NSVT, 46.6% vs. 26.3%, P<0.001). The multivariable Cox proportional hazard analysis showed that PVC burden was a significant risk factor of cardiac events with a hazard ratio (HR) of (P=0.012) after the adjustment of multiple confounders. In addition, NSVT was also a significant risk factor of cardiac events with a HR of (P=0.014). ROC analysis showed PVC burden (> 0.14%/ day) to be a predictive factor of cardiac events (area under the curve: 0.637). In subgroup analysis, study subjects (n=435) were divided into three groups based on PVC burden and prevalence of NSVT: Group 1 (PVC of 0.14%/day and non- NSVT, n=204), Group 2 (PVC of >0.14%/day and non-nsvt or PVC of 0.14%/day and NSVT, n=113) and Group 3 (PVC of >0.14%/day and NSVT, n=105). Cardiac events were 18.7% in Group 1, 28.2% in Group 2 and 43.6% in Group 3, respectively. The multivariable Cox proportional hazard analysis showed that Group 3 was an independent predictor for cardiac events as compared to Group 1 (HR, 2.755, P<0.001). However, Group 2 did not show significant difference compared to Group 1 (P=0.096). Conclusion: In HF patients, PVC burden and prevalence of NSVT were significantly associated with cardiac events. The combination of PVC and NSVT provided a better predictive value of cardiac events.

66 Poster Session V S553 B-PO GENDER EFFECT ON THE ASPECTS OF GENOTYPE PHENOTYPE CORRELATION AMONG CONGENITAL LONG QT SYNDROME PATIENTS Yaxun Sun, MD, PhD, Hector Barajas Martinez, PHD, FHRS, Cuilan Li, PhD, Yoshiyasu Aizawa, MD, PHD, FHRS, Shogo Ito, MD, PhD, Norma Balderrábano-Saucedo, MD, PhD, Karla Sarahi Cano-Hernandez, MD, MSc, Molina Luis, MD, Guosheng Fu, MD, PhD, Chenyang Jiang, MD, PHD, FHRS, Wenling Liu, MD, Dayi Hu, MD, Ryan Pfeiffer, BS, Yuesheng Wu, MD, Tabitha Carrier, BS and Dan Hu, MD, PHD, FHRS. Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, HangZhou, China, Masonic Medical Research Lab, NY, People s Hospital of Peking University, Beijing, China, Keio University, Tokyo, Japan, Children s Hospital of Mexico Federico Gómez, México, D.F., Mexico, Electrophysiology Cardiac Unit, UNAM, The General Hospital of Mexico, Mexico City, Mexico, Masonic Medical Research Lab, Utica, NY Background: Although gender differences in the genetic background and clinical outcome among patients with Long QT syndrome (LQTS) has been reported in some studies, systematic analysis is still lacking. Objective: This population study is aimed to perform a comprehensive comparison of genotype-phenotype correlation between male and female. Methods: A total of 603 patients with LQTS from 6 international registry centers (female, 65.8%; and age 21.8±17.8 yr) were included in the study. The pathogenic mutations were screened in LQTS candidate genes. Its correlation with clinical manifestation was also assessed. The proportional-hazards survival model and the trend analysis in QTc and major cardiac events (MCE) were conducted. Results: Totally, 62.4% patients were positive in KCNQ1, KCNH2 and SCN5A genes, and 12.7% patients were positive in other LQTS candidate genes. Forty-three novel mutations and 144 reported mutations were identified in LQT1-3. Thirtyseven (12.1%) patients carried more than one mutation. The average QTc are longer in female than in male (514±55ms vs. 499±51ms, P<0.01). Among them, female with MCE also showed longer QTc than in male (533±51ms vs. 500±56ms, P<0.01). In patients with QTc 500ms, female showed higher risk of MCE than male (21.9% vs. 11.5%, OR: 2.15, 95%CI: 1.0~4.6, P=0.048). With the augmentation of the QT prolongation, the trend of increased risk of MCE was discovered in female LQT patients, but not in male (P=0.01 & 0.62, respectively). The similar results were confirmed in female LQT probands, as well as female LQT 1~3 patients and probands. As far as the mutation type, female with non-missense mutation had a higher risk of syncope or MCE than those with missense mutation, which was not observed in male group (female: OR 2.2, 95%CI: 1.2~3.9, P<0.01; male: P=0.62). Conclusion: With dozens of newly discovered mutations, we provide novel insight into the genetic mutation and its clinical influence in patients with LQTS. It is important to recognize that QTc prolongation is a valuable prediction index of MCE in female, which suggests a close attention should be drawn in female with remarkable QTc augmentation. And the type of genetic mutation may help to further distinguish the high risk LQTS subgroups. B-PO TEXTURE FEATURES OF THE GRAY ZONE IDENTIFIED WITH CONTRAST-ENHANCED MAGNETIC RESONANCE IMAGING PREDICT VENTRICULAR TACHYARRHYTHMIA IN PATIENTS WITH SYSTOLIC HEART FAILURE Chen Lin, PhD, Van-Truong Pham, PhD, Lian-Yu Lin, MD, PhD, Thi-Thao Tran, PhD, Wen-Yih I. Tseng, MD, PhD, Jiunn-Lee Lin, MD, PhD, Chi-Ho Tseng and Men-Tzung Lo, PhD. National Central University, Taoyuan City, Taiwan, Hanoi University of Science and Technology, Hanoi, Viet Nam, National Taiwan University Hospital, Taipei, Taiwan, National Central University, Taoyuan City, Taiwan Background: Sudden cardiac death is a major cause of death in patients with systolic heart failure (HF). Peri-scar area (gray zone) detected by late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) imaging could help identify high risk patients. Objective: We hypothesized that the texture features of the gray zone can provide additional information. Methods: A total of 82 systolic HF patients with LGE-CMR imaging were enrolled. The cine and LGE images were analyzed to derive the left ventricular (LV) function and scar characteristics. After 5-year follow up, 10 patients had VT/ VF attacks and 9 patients died of cardiovascular diseases. To identify the infarct zone, we chose 2 SDs and 3 SDs intensity thresholds of the image because the area produced by this threshold closely matches with that is shown on the LGE images by visual inspection. Furthermore, the heterogeneity of the scar region was assessed by two texture parameters, uniformity (the homogeneity of gray-level distribution) and entropy (the irregularity of gray-level distribution), and were averaged among all slices. Results: The entropy of the gray zone (0.48 [ ] vs [ ], p = 0.024) was higher in cardiac mortality group than the survival group while the uniformity (0.74 [ ] vs [ ], p = 0.028) was lower in cardiac mortality group than the survival group while the entropy (0.38 [ ] vs [ ], p = 0.074) and the uniformity (0.79 [ ] vs [ ], p = 0.063) of the gray zone was borderline different between patients with and without VT/VF. The other LGE-MRI variables were not significantly different between the two groups. In addition, higher entropy (> 0.48) was associated with VT/VF attacks (HR = 5.036, , p = 0.022) as well as the cardiac mortality (HR = 7.000, , p = 0.006). Higher uniformity (>0.74) lowered the risk of VT/ VF attacks (HR = 0.217, , p = 0.030) and cardiac mortality (HR = 0.154, , p = 0.009). Conclusion: The heterogeneity property of gray zone can provide additional information associated with VT/VF events or mortality compared to other often-used parameters of the LGE- CMR image in patients with HF. B-PO CARDIAC MRI IS SUPERIOR TO CARDIAC PET IN PREDICTING VENTRICULAR ARRHYTHMIAS IN PATIENTS WITH CARDIAC SARCOIDOSIS Zain Gowani, MD, David Robert Okada, MD, John Nikolhaus Smith, Arsalan Derakhshan, Satish K. Misra, MD, Fabrizio R. Assis, MD, Ronald D. Berger, MD, PhD, FHRS, Harikrishna Tandri, MD and Jonathan Chrispin, MD. Johns Hopkins Medicine, Baltimore, MD, Johns Hopkins Hospital, Baltimore, MD, Baltimore, MD, Johns Hopkins University, Baltimore, MD, Johns Hopkins University School of Medicine, Parkville, MD, The Johns Hopkins Hospital, Baltimore, MD, Johns Hopkins School of Medicine, Lutherville-Timonium, MD

67 S554 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Background: Patients with cardiac sarcoidosis (CS) are at increased risk of ventricular arrhythmias (VA). Objective: Our aim was to assess the utility of cardiac magnetic resonance imaging (CMR) and cardiac positron emission tomography (PET) in predicting risk of ventricular arrhythmic events (VA). Methods: 45 consecutive patients with CS underwent both CMR and PET at our institution between 2000 and The primary endpoint was VA at follow-up, which was defined as ventricular fibrillation, sustained ventricular tachycardia, sudden cardiac death, or device therapy. Results: Mean age was 51+/-10 years; 42% were female; Mean LVEF was 54% +/-14%. 30 (67%%) patients had late gadolinium enhancement on CMR (+LGE), among whom 18 (40%) had abnormal 18-FDG uptake on PET (+LGE/+FDG) and 12 (27%) did not (+LGE/-FDG). Overall, 6 (20%) LGE+ patients had VA. Among +LGE/+FDG patients 3 (17%) had VA. Among +LGE/- FDG patients 3(25%) had VA. 15 (33%) patients had no LGE but had abnormal FDG uptake (-LGE/+FDG). Among -LGE/+FDG patients, 1 (7%) had VA. Relative risk of VA for patients with +LGE with or without FDG was 3.0 in comparison to those with +FDG without LGE (95% CI ( )). Conclusion: There is a strong trend that CMR is a better predictor for VA than PET in patients with CS. Among patients with LGE on CMR, the presence or absence of abnormal 18- FDG uptake on PET does not predict arrhythmic outcomes. Patients without LGE have low rates of VA. B-PO BIOLOGICAL AGE AS A PREDICTOR OF ATRIAL FIBRILLATION AND CARDIOVASCULAR EVENTS: A META- ANALYSIS Mehrdad Emami, MD, Thomas A. Agbaedeng, BBS, Kadhim Kadhim, MBChB, Ricardo Sadashi Mishima, MD, Anand Thiyagarajah, MBBS, Dian A. Munawar, MD, Kashif B. Khokhar, MBBS, Dominik K. Linz, MD, PhD, Jeroen ML. Hendriks, MS, PhD, RN, Melissa E. Middeldorp, Celine Gallagher, RN, Rajiv Mahajan, MD, PhD, FHRS, Dennis H. Lau, MBBS, PhD, FHRS and Prashanthan Sanders, MBBS, PhD, FHRS. Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia, Centre for Heart Rhythm Disorders, The University of Adelaide, South Australian, Adelaide, SA, Australia, Adelaide, SA, Australia, University of Adelaide, Beaumont, SA, Australia, Centre of Heart Rhythm Disorders, Forestville, Australia, Royal Adelaide Hospital, Centre of Rythm Disorders, Adelaide, Australia, University of Adelaide, Adelaide, SA, Australia, Centre for Heart Rhythm Disorders - University of Adelaide, Adelaide, Australia, Centre for Heart Rhythm Disorders, Norwood, Australia, Cardiology, Beaumont, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia Background: Chronological age is the most common risk factor for atrial fibrillation (AF). Telomere length is a marker of biological age. The association between biological age and AF, AF risk factors, and cardiovascular events is not well established Objective: The association between leukocyte telomere length (LTL) as an aging marker and its role in predicting AF, hypertension (HTN), diabetes mellitus (DM), myocardial infarction (MI), and stroke was investigated in a meta-analysis Methods: A broad computerised literature search on PubMed and EMBASE limited to human studies was performed using the words AF, HTN, DM, MI, stroke, and LTL in different formats and spellings from inception to October After exclusions, 21 studies were identified with a total of 63,514 participants. Studies were pooled per their primary outcome into five different meta-analyses (AF, HTN, DM, MI, and stroke). The results were presented as odds ratio (OR). LTL was measured by quantitative PCR and presented as the ratio of telomeric DNA (T) to a single copy reference DNA (S): T/S ratio. LTL was presented in quartiles with Q1 representing the shortest Results: For AF, the pooled analysis of 11,351 participants demonstrated that shorter LTL is strongly associated with a higher risk of AF compared to longer LTL [OR 1.27 ( ), p=0.003] even when adjusted for other variables including chronological age. Shorter LTL was strongly associated with higher risk of MI when adjusted to other variables [OR 1.57 ( ), p=0.007]. The association of LTL with HTN [OR 1.18 ( ), p=0.5], DM [OR 1.39 ( ), p=0.12], and stroke [OR 1.37 ( ), p=0.06] was not significant Conclusion: Biological age is strongly associated with the risk of AF and MI independent of other variables including chronological age. Biological age and its biomarkers may help identify the population at risk of AF, MI, and stroke B-PO HOW TO DETERMINE THE QT INTERVAL: A COMPREHENSIVE ANALYSIS OF A LARGE COHORT OF LONG QT SYNDROME PATIENTS AND CONTROLS A.S. Vink, MD, MSc, Benjamin Neumann, Krystien V.V. Lieve, MD, Nynke Hofman, MSc, S. el Kadi, BSc, M.H.A. Schoenmaker, BSc, H.M.J. Slaghekke, BSc, Sally-Ann Barker Clur, Nico A. Blom, MD, PhD, Stefan Kaab, MD, PhD, Moritz F. Sinner, MD, Arthur A. M. Wilde, MD, PhD and Pieter G. Postema, MD. Academic Medical Center, Amsterdam, Netherlands, University Hospital Munich, Ludwig-Maximilians- University, Munich, Germany, AMC, Amsterdam, Netherlands, Emma Children s Hospital, Academic Medical Center, Abcoude, Netherlands, Leiden University Medical Center, Leiden, Netherlands, Ludwig Maximilians University Hospital, Munich, Germany, LMU Munich, Campus Grosshadern, Munich, Germany, Univ of Amsterdam - Academic Medical Center, Amsterdam, Netherlands, Academic Medical Center, Cardiology Dept, Amsterdam, Netherlands Background: Long QT syndrome (LQTS) is associated with potentially fatal arrhythmias at young age. Treatment is very effective but its diagnosis may not be simple. Importantly, different methods are used to assess the QT interval, which troubles its recognition. QT experts advocate manual measurements with the tangent or threshold method. However, differences between these methods and their performance in LQTS diagnosis have not been established. Objective: To assess differences between these two methods for QT analysis. Methods: Confirmed pathogenic mutation carriers in KCNQ1 (LQT1), KCNH2 (LQT2) and SCN5A (LQT3) genes were included as LQTS cases and their genotype-negative family members as controls. Consecutive complexes from baseline ECGs were analyzed with both methods in two separate sessions by three readers. One reader additionally remeasured 10% of the ECGs Results: We included 1492 individuals (subgroups: 301 LQT1, 370 LQT2, 139 LQT3 and 599 controls) from 267 families, aged 33±21 years and 55% female. In the total cohort, QT tangent was 10.5 ms shorter (p<0.0001) compared to QT threshold (95% limits of agreement ± 20.5 ms). In all the subgroups, QT tangent was shorter (p<0.0001) compared to QT threshold, but this was less pronounced in LQT2. Both methods had a high inter- and intra-observer validity (intraclass correlation coefficient >0.96), and a high distinctiveness between LQTS patients and controls (area under the curve >0.84). Using the current guideline cut off value (QTc 480 ms), both methods had similar specificity (100%

68 Poster Session V S555 versus 99%) but the QT threshold yielded a higher sensitivity (19% versus 26%). Optimal cut off value for males was QTc tangent 416 ms (73% sensitivity,84% specificity) and QTc threshold 433 ms (67% sensitivity, 88% specificity). For females QTc tangent 434 ms (71% sensitivity, 90% specificity) and QT threshold 444 ms (69% sensitivity, 89% specificity). Conclusion: The length of the QT interval is different depending on the method used for determination. Both methods have a high validity. However, for diagnostic purposes current guideline cut off values yield different results for these two methods, and could result in inappropriate reassurance or treatment. Adjusted cut off values are suggested to diagnose LQTS. B-PO HEART FAILURE DUE TO HIGH DEGREE ATRIO- VENTRICULAR BLOCK: HOW FREQUENT IS IT AND WHAT IS THE CAUSE? Dana Viskin, Amir Halkin, MD, Jack Sherez, Ricki Megidish, Dana Fourey, Gad Keren and Yan Topilsky. Tel Aviv Sourasky Medical Center, Tel Aviv, Israel, Tel Aviv Sourasky Medical Center Background: The causes of syncope and effort intolerance during high-degree atrio-ventricular block (AVB) are well described. On the other hand the reasons for clinical heart failure (HF) during AVB are poorly understood. Objective: To assess the incidence and mechanisms of HF during AVB. Methods: We studied 122 patients presenting with high degree AVB not due to acute myocardial infarction and free of significant valvular heart disease. All patients underwent clinical evaluation for symptoms and signs of HF as well as a comprehensive echocardiographic evaluation prior to pacemaker implantation. The diagnosis of HF was based on the Framingham criteria. Results: We studied 122 patients, 50% male, aged 76±13. Twenty-eight (23%) of patients with AVB presented with HF. Interestingly, the ventricular rate during AVB and the left ventricular (LV) ejection fraction were not significantly associated with the presence of HF. Univariate correlates of HF were low cardiac output [0.67 ( ) liter/min, p=0.007], measures of impaired LV compliance and diastolic mitral regurgitation (MR) volume [1.04 ( ), p=0.0016]. By multivariate analysis, the best model associated with HF included a high diastolic MR volume [OR 1.03 ( ), p=0.03], and low cardiac output [OR 0.72 ( ), p=0.05], (X 2 = 30.6; AUC 0.84; p< for the entire model). Conclusion: During high-degree AV block, not all the P-waves immediately precede R-waves. As a direct consequence of this electrical atrio-ventricular desynchronization, not only the atrial systole, but also the atrial relaxation, are not properly timed with the ventricular systole, which in turn dictates the timing of mitral valve opening and closure. Every beat of atrial diastole taking place when the mitral valve is wide opened may lead to significant diastolic mitral regurgitation through a atrial suction mechanism, particularly in patients with non-compliant left ventricle. Therefore, during high degree AVB, the presence of clinical HF does not correlate with the ventricular rate or the ejection fraction. Instead, HF during AVB correlates with the presence of reduced LV compliance, low CO, and a higher volume of diastolic MR. B-PO ARRHYTHMOGENICITY OF ISOPROTERENOL IN ASYMPTOMATIC GENE CARRIERS UNMASK ELECTRICAL SUBSTRATE RELATED TO ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY (ARVC) Arnaud Denis, MD, Nicolas Derval, MD, Frederic Sacher, MD, Thomas Pambrun, Josselin Duchateau, MD, MSc, Ghassen Cheniti, MD, Masateru Takigawa, MD, Konstantinos George Vlachos, MD, PhD, Anna Lam, MD, Antonio Frontera, Claire A. Martin, MA, MBBS, PhD, Felix Bourier, MD, Takeshi Kitamura, Hubert Cochet, MD MSc, Meleze Hocini, MD, Pierre Jais, MD and Michel Haissaguerre, MD, PhD. Chu Bordeaux, Pessac Cedex, France, Hopital Cardiologique Du Haut-Leveque, Pessac, France, LIRYC Institute/ Bordeaux University Hospital, Bordeaux, France, Centre Hospitalier Universitaire, Bordeaux, France, IHU-LIRYC, Pessac, France, CWT Meetings & Events, Mélissa Pernot, Boulogne-Billancourt Cedex, France, Yokosuka Kyosai Hospital, Yokosuka, Japan, Pessac,Bordeaux, France, Hôpital Cardiologique du Haut-Lévêque - CHU de Bordeaux, Bordeaux-Pessac, France, Bordeaux, France, LIRYC institute - Hôpital Haut Lévêque, Pessac Cedex, France, Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom, Deutsches Herzzentrum, Munich, Germany, Université de Bordeaux, Bordeaux, France, Hôpital Haut-Lévêque, Bordeaux, France, Boulogne-Billancourt Cedex, France Background: Management of asymptomatic ARVC gene carriers is challenging because of the variable penetrance of the disease. Objective: We hypothesized that isoproterenol testing may unmask underlying electrical substrate in asymptomatic ARVC gene carriers. Methods: First-degree relative of mutation-carriers ARVC patients were evaluated by 12 leads ECG, holter monitoring, signal average ECG, exercise test, cardiac magnetic resonance imaging (MRI) and isoproterenol testing (continuous infusion of isoproterenol, 45 µg/min over 3 minutes). In the settings of familial screening, isoproterenol testing was considered positive if at least 2 different morphologies of premature ventricular contraction with left bundle branch block morphology occurred during the test or within 10 minutes after the end of infusion. Results: Forty-one first-degree relative (49% male, aged 42±14 years) belonging to 15 families were included. Thirtynine patients were asymptomatic and 2 had palpitations. Familial mutations were found in 25/41 (61%) patients. Six mutation carriers displayed T wave inversion in V1 to V3 compared to 0/16 non-mutation carriers (p=0.04). SAECG, 24 hours holter ECG monitoring and MRI were not significantly different in mutation carriers compared to non-mutation carriers (13/25 (52%) vs 4/16 (25%), p=0.09; 2/25 (8%) vs 0/16 (0%), p=0.4; and 2/25 (8%) vs 0/16 (0%), p=0.4, respectively). Arrhythmogenicity during isoproterenol testing was observed in 20/25 (80%) mutation carriers and in 1/16 (6.2%) patients without mutation (p<0.001). Arrhythmogenicty during isoproterenol testing was also demonstrated in all 8 probands in whom isoproterenol testing was performed. Conclusion: Arrhythmogenicity revealed by isoproterenol testing in asymptomatic mutation carriers may unmask an underlying electrical substrate and may be useful for risk stratification. B-PO QUANTIFYING OUT OF HOSPITAL PREMATURE DEATH IN A RURAL COMMUNITY Irion W. Pursell, BSN, RN FA, Jessica Ford, PhD, Cornelia Virus, PhD, Samuel Sears, PhD, Ashley Griffith, Grayson Chappell and J. Paul Mounsey, MBChB, PhD. East Carolina

69 S556 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Heart Institute, Greenville, NC, East Carolina University, Greenville, NC Background: Rural populations are medically underserved and have less access to preventative care. Emergency Medical Services response times are usually longer. Cardiac sudden death, restrictively defined to maximize potential candidates for resuscitation, is underestimated in rural communities because of these access issues. In an attempt to quantify the magnitude of the problem we assessed out of hospital premature natural death (OHPND) in a large rural community, a cohort that includes all cardiac sudden death victims. Objective: To quantify and characterize OHPND victims in a large rural population in Eastern North Carolina Methods: All deaths (12,665) for 2014 from 29 counties in Eastern North Carolina (Population 1,424,876) were electronically filtered cases of OHPND (18-74 years old, natural causes, that died out of the hospital and were both a resident of and died in the same county) were identified. Deaths where primary cause was cancer were excluded. Primary cause of death was determined using International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) data from the death certificates. OHPND cases were mapped using victim s residence address. Results: OHPND cases represent 12% of all natural deaths in adults under age 75. Among 1122 OHPND cases, 405 were female and 717 male OHSUD cases, average age was 62 for women and 61 for men. 39% of cases were referred to the medical examiner to determine cause of death vs 5% in the general population. Diseases of the circulatory system identified as the primary cause of death in OHPND victims (52%) was higher than the state average (18%), as was respiratory diseases (16% vs 6%) and endocrine disease (16% vs 4%). GPS mapping of residence addresses shows OHPND clusters in low socioeconomic areas. Conclusion: OHPND was primarily the result of cardiovascular disease and this is driven by cardiac sudden death. Neighborhoods with high incidence of OHPND could be identified. We plan community engagement and intensive preventative health care efforts in these communities with the goal of reducing cardiac sudden death. B-PO HIGH EFFICACY AND SAFETY OF AUTOMATED EXTERNAL DEFIBRILLATORS IN THE SUBWAY SYSTEM OF MUNICH DURING LONG-TERM FOLLOW-UP Markus Matula, MD, Anna Maria Riedel, Josef Assal, MD, Karl- Georg Kanz, MD and Thomas Korte, MD. Ludwigs-Maximilian University, Munich, Germany, Technical University, Munich, Germany Background: Automated external defibrillators (AED) are available in many public places. However, it is not known where AEDs yield their highest efficacy. Placement of AEDs has been recommended at sites with a high likelihood of witnessed cardiac arrest, although there has been no standardized approach for optimal placement of AEDs in large cities. Objective: This study investigates the efficacy and safety of publicly accessible AEDs in the Munich subway system over a period of 15 years. Methods: From April 2001 to December AEDs were installed at all 100 stations of the Munich subway system. By taking the defibrillators from the SOS pillar, the rescue chain has been acitvated in all cases. After using an AED, stored data were collected from the device as well as the records of the rescue service and all available hospital documents. Results: From April 2001 to December 2016 AEDs have been used in 78 passengers of the Munich subway. In all cases the heart rhythm has been analysed and classified correctly by the AED. Subsequentely defibrillators recommended shock treatment only for shockable rhythms like VF or VT. 38 of 78 pts showed VF or VT on the initial electrogramm. One to five shocks were delivered. In 27 cases the first shock convertet the arrhythmia to SR. 7 of those resumed VF/VT. In 13 cases the second shock convertet the arrhythmia to SR. 11 of those resumed VF/VT. Eight pts required three shocks. A maximum of five shocks was successful in terminating VF/VT in all remaining cases. The time from the initial SOS call and the first shock, averaged to 5:38 min ± 3:36 min corresponding to a survival rate of 57% without neurologic damage. Conclusion: Systematic use of AEDs in the Munich subway system is highly effective and safe for the acute treatment of patients with cardiac arrest. B-PO ELECTROCARDIOGRAPHIC SCREENING OF 1-MONTH- OLD INFANTS TO PREVENT SUDDEN INFANT DEATH Masao Yoshinaga, MD, PhD, Hiroya Ushinohama, MD, PhD, Seiichi Sato, MD, PhD, Hitoshi Horigome, MD, PhD, Tadayoshi Hata, MD, PhD, Nobuo Tauchi, MD, PhD, Eiki Nishihara, MD, PhD, Naokata Sumitomo, MD, PhD, Ayaka Ozawa, MD, PhD, Fukiko Ichida, MD, PhD, Hirohiko Shiraishi, MD, PhD, Yuichi Nomura, MD, PhD, Yuu Kucho, Hideto Takahashi, PhD, Seiko Ohno, MD, PhD and Masami Nagashima, MD, PhD. National Hospital Organization Kagoshima Medical Center, Kagoshima, Japan, Ohori Children s Clinic, Fukuoka, Japan, Okinawa Prefectural Nanbu Medical Center & Children s Medical Center, Okinawa, Japan, University of Tsukuba, Tsukuba, Japan, Fujita Health University, Toyoake, Japan, Aichi Saiseikai Rehabilitation Hospital, Nagoya, Japan, Ogaki Municipal Hospital, Ogaki, Japan, Saitama Medical University International Medical Center, Hidaka, Japan, Toyama University Hospital, Toyama, Japan, Toyama University Graduate School of Medicine, Toyama, Japan, International Pediatric Center Josai Hospital, Ibaraki, Japan, Kagoshima City Hospital, Kagoshima, Japan, National Institute of Public Health, Wako, Japan, Shiga University of Medical Science, Ohtsu, Japan Background: Prospective studies on the prevalence and prognosis of infants with long QT syndrome (LQTS) had been reported in Italy and Japan. Approximately 10% of sudden infant death syndrome victims have pathogenic mutations of LQTS. Objective: To determine the prevalence and prognosis of infants with LQTS confirmed by 1-month ECG screening. Methods: Prospective screenings were performed twice in 8 areas in Japan at 1-month medical checks (Table). The QT/RR intervals of 3 consecutive beats in 12-lead ECGs were measured and corrected by Bazett s formula. A prospective study showed that a provisional criterion of QTc 470 ms was appropriate for infants. Medication was started when an infant showed a QTc 500 ms in Holter ECG. For infants with a QTc 470 ms, genes related to LQTS, CPVT, and Brugada syndrome were screened using a next generation sequencer. One year after screening, questionnaires were sent to the maternity hospitals and parents regarding the presence or absence of sudden death. Results: A total 10,325 infants participated in 2 studies. The mean QTc values and the prevalence of infants with LQTS and medication were the same between the 2 studies. Gene testing showed one pathogenic mutation (3065 delt, L1021fs+34X) and one SNP (K897T, 2690A>C) in KCNH2 in an infant each. No infants with LQTS died. Medication was stopped at approximately 1.5 years because the QTc values decreased. Sudden death occurred in 3 infants without QT prolongation. Conclusion: The prevalence of infants with LQTS and those

70 Poster Session V S557 with medication was the same in 2 different studies. ECG screening may prevent infants from sudden death by arrhythmia syndromes. Cost-effective analysis is warranted. Characteristics of Participants 1st Study 2nd Study Total Period No of participants ,325 QTc {mean (SD)} 412 (19) 413 (20) 412 (19) LQTS (QTc>=470 ms) 4 (1/1080) 6 (1/1001) 10 (1/1033) Medication (QTc>=500 ms) 2 (1/2160) 3 (1/2002) 5 (1/2062) Sudden death with QT prolongation Sudden death w/o QT prolongation B-PO METABOLIC SYNDROME AND THE RISK OF NEW-ONSET ATRIAL FIBRILLATION IN MIDDLE-AGED EAST ASIAN MEN Yong Giun Kim, MD, Ki Won Hwang, MD, Chang Hee Kwon, Hyung Oh Choi and Kee-Joon Choi, MD. Asan Medical Center, Seoul, Korea, Republic of, Konkuk Medical Center, Seoul, Korea, Republic of, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea, Republic of Background: The components of metabolic syndrome have been implicated in the development of atrial fibrillation (AF). Although the prevalence of AF has been increasing in East Asia, the association between metabolic syndrome and AF is uncertain. Objective: This study aimed to determine the association between metabolic syndrome and AF in middle-aged East Asian men. Methods: A total of 24,741 middle-aged Korean men without baseline AF were enrolled in a health screening program from January 2003 to December Among them, 21,981 subjects were evaluated to determine the risk of AF based on baseline metabolic syndrome status through December At every visit, the subjects were evaluated for AF using electrocardiography. Metabolic syndrome was defined using the criteria of the International Diabetes Federation. Results: Metabolic syndrome was present in 2529 subjects (11.5 %). Mean (± standard deviation) age was 45.9 ± 5.3 years. During a mean follow-up of 8.7 years, 168 subjects (0.8%) were diagnosed with AF. The age-adjusted and multivariate-adjusted hazard ratios (HR) for metabolic syndrome with AF were 1.62 (95% confidence interval [CI] , p=0.02) and 1.57 (95% CI , p=0.03), respectively. Among the components of metabolic syndrome, central obesity (age-adjusted HR 1.62, 95% CI , p<0.01) and raised blood pressure (ageadjusted HR 1.43, 95% CI , p=0.02) were associated with an increased risk of AF. Conclusion: Metabolic syndrome was associated with an increased risk of AF in middle-aged East Asian men. Of the components of metabolic syndrome, central obesity was the most potent risk factor for the development of AF in this population. Risk of AF according to metabolic syndrome: age- and multivariate- adjusted models Age-adjusted HR (95% CI) p value Multivariate-adjusted HR (95% CI) p value Metabolic syndrome 1.62 ( ) ( ) 0.03 Components of metabolic syndrome Central obesity 1.62 ( ) < ( ) <0.01 Raised blood pressure 1.43 ( ) ( ) 0.06 Raised fasting plasma 1.16 ( ) glucose ( ) 0.75 Raised triglycerides 0.84 ( ) ( ) 0.7 Reduced HDL-C 1.04 ( ) ( ) 0.74 B-PO INCREASED RISK OF CANCER IN PATIENTS WITH NEWLY DIAGNOSED ATRIAL FIBRILLATION: A NATIONWIDE POPULATION-BASED STUDY Won-Seok Choe, MD, Eue-Keun Choi, MD, PhD, Kyung-Do Han, Eue-Jae Lee, So-Ryoung Lee, Myung-jin Cha, Woo- Hyun Lim, MD and Seil Oh, MD, PhD, FHRS. Seoul National University Hospital, Seoul, Korea, Republic of, Seoul National University Hospital Department of Internal Medicine, Seoul, Korea, Republic of, College of Medicine, The Catholic University, Seoul, Korea, Republic of, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea, Republic of, Boramae Medical Center, Seoul, Korea, Republic of Background: Non-cardiovascular death is known to have substantial proportion of cause of death in patients with atrial fibrillation (AF). However, there are a few reports about the association between AF and cancer. Objective: We sought to evaluate the risk of cancer in patients with AF in a population based study. Methods: We enrolled 438,715 patients with AF ( 40 year-old, mean age 63.8 years, male 52%) without history of cancer from Korean National Health Insurance Service database between 2007 and Newly diagnosed cancer was identified using the claims data. Age- and sex-matched control subjects (1:5, n=2,192,650) were selected and compared with AF patients. Results: During a mean 4.8 years of follow-up, cancer were newly diagnosed in 121,884 patients (crude incidence rate of 10.6 per 1000 person-years [PY] in AF and 9.39 per 1000 PYs in control). Most common incident cancer in AF patients were colon, stomach, lung, and liver cancer. Overall, AF was a significant risk factor for cancer in multivariable-adjusted model (HR 1.07; 95% CI ). However, there were considerable disparities in the association between AF and the type of cancer. AF showed an increased risk of cancer, especially for neural tissue, larynx, liver, kidney, ovary, thyroid, esophageal cancers, and hematologic malignancies (Figure). However, these was no difference in the risk of breast, uterus, stomach, colon, prostate and testis cancers between AF and non-af group. In addition, the impact of AF on incident cancer was remarkable among subjects with younger age (<65 years) and less comorbidities. Conclusion: In this population-based study, patients with newly diagnosed with AF had an increased risk of cancer.

71 S558 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO B-PO VARIABILITY OF METABOLIC PARAMETERS, A NOVEL PARAMETER TO PREDICT THE RISK OF ATRIAL FIBRILLATION IN HEALTHY POPULATION: A NATIONWIDE POPULATION-BASED STUDY So-Ryoung Lee, MD, Eue-Keun Choi, MD, PhD, Kyung-Do Han, Seung-Hwan Lee, MD, PhD and Seil Oh, MD, PhD, FHRS. Soon Chun Hyang University Hospital Seoul, Seoul, Korea, Republic of, Seoul National University Hoispital, Seoul, Korea, Republic of, The Catholic University of Korea, Seoul, Korea, Republic of, Seoul St. Mary s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea, Republic of, Seoul National University Hospital, Seoul, Korea, Republic of Background: The variability of metabolic parameters might have an impact on the pathophysiology of atrial fibrillation (AF). Objective: We sought to evaluate the effect of the variability of 4 metabolic components including systolic blood pressure (BP), glucose, total cholesterol (TC), and body mass index (BMI) on the risk of AF. Methods: We identified 6,819,829 subjects (mean age, 42.9±12.1; men, 57.3%) without prevalent hypertension, diabetes, or dyslipidemia who had 3 health checkups provided by the Korean National Health Insurance Corporation between 2009 and Glucose, BP, TC, and BMI were measured at each visit. Variability of each parameter was defined as variability independent of the mean (VIM), and VIM of each parameter was divided into four groups. High variability was defined as having values in the highest quartile of each parameter. Results: During a mean 5.3 ± 1.1 years of follow-up, 31,302 subjects were newly diagnosed with AF (0.86 per 1,000 person-years). Subjects with the highest VIM quartile of BP, TC, and BMI showed an increased risk of AF compared to those with the lowest VIM quartile, whereas glucose variability had a marginal association. The composite of high variability of metabolic parameters showed a graded risk of AF (Figure). After multivariable adjustment, subjects having 1, 2, 3, and 4 parameters of the highest VIM had an approximately 7, 13, 20, and 35% increased risk of AF compared to those without any highest variability of metabolic parameters. Conclusion: The variability of metabolic parameters showed a close association with the risk of AF in those without cardiovascular comorbidities including hypertension, diabetes or dyslipidemia. THE ACCURACY OF AMPLITUDE-BASED ALGORITHMS TO LOCALIZE ACCESSORY PATHWAY DURING MAXIMAL PREEXCITATION Pawel Jerzy Moskal, MD, Marek Jastrzębski, MD, PhD and Danuta Czarnecka, MD, PhD. 1st Department of Cardiology, Interventional Electrocardiology and Arterial Hypertension, Jagiellonian University Medical College, Krakow, Poland, 1st Department of Cardiology, Interventional Electrocardiology and Arterial Hypertension Jagiellonian University Medical College, Krakow, Poland Background: To aid approximation of accessory pathway (AP) localization in patients with Wolff-Parkinson-White syndrome various electrocardiographic criteria were developed. However, these algorithms were validated in resting ECGs where QRS complexes consist of a wide-range fusion of atrioventricular and accessory pathway conduction. Objective: The aim of this study is to assess accuracy of three amplitude based algorithms (D Avila, Iturralde, Taguchi) in localizing accessory pathway in ECGs where maximal preexcitation is present. Methods: We performed a retrospective study of consecutive, single anterogradely conducting AP ablation procedures to acquire ECGs with maximal preexcitation during fast-paced atrial rhythm. Among 670 procedures we identified 304 cases with adequate quality ECGs. We analyzed electrocardiograms using three amplitude based algorithms (D Avila, Iturralde, Taguchi) to determine their accuracy. Results: The overall absolute accuracy of the evaluated algorithms: D Avila, Iturralde, Taguchi were 28%, 69% and 73% respectively. When a simplified pattern of 5 regions of AP localization was used, the accuracy of D Avila s algorithm increased to 62%. The most common error of Taguchi algorithm was misclassification of posteroseptal and mid-septal APs as left posterior or right posterior AP (50% of all errors) and transposing left lateral/left anterior and left posterior/left posterolateral localization (28% of all errors). The most common error of D Avila s algorithm was classification left posterior or left posterolateral AP as posteroseptal (41% of all errors). There were 4%, 1.3%, and 1.6% major errors in identification of right and left-sided AP using D Avila, Iturralde, Taguchi algorithm respectively. Conclusion: Taguchi s algorithm is the most accurate amplitude based algorithm for localizing AP when maximal preexcitation is present.

72 Poster Session V S559 B-PO THE P WAVE MORPHOLOGY PATTERN IN V7 ON THE SYNTHESIZED 18-LEAD ECG IS A NOVEL AND SIMPLE PARAMETER FOR DIFFERENTIATING ORIGINS FROM THE RIGHT INFERIOR PULMONARY VEIN Kaori Hisazaki, MD, Kenichi Kaseno, MD, PhD, Kanae Hasegawa, MD, PhD, Naoki Amaya, MD, PhD, Shinsuke Miyazaki, MD, PhD, Naoto Tama, MD, PhD, Hiroyuki Ikeda, MD, PhD, Yoshitomo Fukuoka, MD, PhD, Tetsuji Morishita, MD, PhD, Kentaro Ishida, MD, PhD, Hiroyasu Uzui, MD, PhD and Hiroshi Tada, MD, PHD, FHRS. Fukui University, Fukui, Japan Background: Atrial tachyarrhythmias and premature beats often originate from the superior vena cava (SVC), right superior (RSPV) and inferior pulmonary veins (RIPV). However, a precise differentiation of those origins is challenging by the standard 12- lead electrocardiogram (ECG) P-wave morphology due to the anatomical proximity. The recently developed synthesized 18- lead ECG provides recordings from the right and posterolateral chest leads. Objective: This study sought to evaluate the utility of the synthesized 18-lead ECG to differentiate atrial arrhythmias originating from 3 adjacent structures. Methods: Synthesized 18-lead ECGs were obtained during pacing from the SVC, RSPV, and RIPV in 20 patients during ablation procedures. P-wave morphologies were classified into 4 patterns: positive, negative, biphasic, and isoelectric. An algorithm predicting the pacing site was initially developed, then evaluated prospectively in 14 patients. Results: Isoelectric P-waves in lead V7 were useful to distinguish RIPV-pacing from the others (17/20 vs. 4/40; P<0.001; sensitivity=81%, specificity=92%, positive predictive value [PPV]=85%, negative predictive value [NPV]=90%). P-wave morphologies in leads IIand V1 were helpful to differentiate SVC-pacing and RSPV-pacing (Figure). In a prospective evaluation, RIPV-pacing was identified using the algorithm with a sensitivity of 92%, specificity of 93%, PPV of 86%, and NPV of 96%. Overall, the 3 pacing sites were identified with a 79% accuracy. Conclusion: The P wave morphology pattern in V7 on synthesized 18-lead ECGs is a simple parameter for differentiating RIPV origins among the 3 adjacent structures. B-PO IMPACT OF CARDIAC SYMPATHETIC DENERVATION ON ATRIAL FIBRILLATION BURDEN IN PATIENTS WITH CARDIOMYOPATHY AND VENTRICULAR ARRHYTHMIAS Natalia M. Vecerek, BA, Julie M. Sorg, RN, MSN, Eric F. Buch, MD, FHRS, Kalyanam Shivkumar, MD, PhD, FHRS and Olujimi A. Ajijola, MD, PhD. David Geffen School of Medicine, Los Angeles, CA, UCLA Health, Los Angeles, CA, University of California - Los Angeles, Los Angeles, CA, UCLA Health System, Los Angeles, CA, University of California, Los Angeles, Cardiac Arrhythmia Center, Sherman Oaks, CA Background: Cardiac sympathetic denervation (CSD) is wellestablished for treating ventricular arrhythmias (VAs). The effects of CSD on atrial fibrillation (AF) remain unclear. Objective: This study aims to determine if there is a relationship between CSD and AF by examining if CSD alters AF burden. Methods: Retrospective analysis of data from 79 thoracic sympathectomy patients (mean age 54 ± 13.9 years; 79.7% male) for their change in burden of AF before and after CSD. All patients suffered from VAs and cardiomyopathy, and had CSD performed at UCLA. AF burden was obtained from implantable cardioverter defibrillator device interrogations present in all patients for secondary prevention, and supplemented by any additional cardiac monitoring available. Death, orthotopic heart transplantation, and initiation of mechanical heart support were endpoints. Results: 40 patients had complete pre-surgical and postsurgical records (mean follow up 12.1±5.3 months); data from device interrogation was analyzed utilizing weighted averages to correct for differing time frames. There was no significant change in AF burden measured as the percentage of time in AF before and after CSD (median AF burden 7.9% vs 7.4% respectively, p=0.9), even when analysis was restricted to patients with preexisting AF. Survival for those with AF was significantly lower with a hazard ratio of 2.64 (p=0.0459); when this was adjusted for age and the presence of kidney disease, the hazard ratio was 2.05 (p=0.2013). Conclusion: These data suggest that AF burden is not decreased following CSD in patients with cardiomyopathy and VAs, and that sympathetic remodeling is not a driver of AF in these patients. AF may be a predictor for adverse outcomes in this patient population. Further study is warranted to examine this relationship. B-PO TRANILAST AND BLOOD PRESSURE LOWERING TREATMENTS PREVENT FIBROTIC SUBSTRATE FORMATION FOR AF VIA BLOCKADE OF WNT/β- CATENIN AND TGF-β SIGNALLING IN SPONTANEOUSLY HYPERTENSIVE RATS Shivshankar Thanigaimani, PhD, Emma McLennan, PhD, Pawel Kuklik, PhD, Thomas A. Agbaedeng, BBS, Dominik K. Linz, MD, PhD, Prashanthan Sanders, MBBS, PhD, FHRS and Dennis H. Lau, MBBS, PhD, FHRS. University of Adelaide, Adelaide, Australia, University Medical Center Hamburg-Eppendorf, Hamburg, Poland, Centre for Heart Rhythm Disorders, The University of Adelaide, South Australian, Adelaide, SA, Australia, University of Adelaide, Adelaide, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia Background: Fibrosis is a fundamental hallmark of hypertensive cardiac remodelling, leading to formation of AF substrate. Wnt/ β-catenin and TGF-β signalling pathway is reported to play an important role. Objective: Here, we assessed the role of Tranilast and antihypertensive treatment in alleviating fibrosis via Wnt/ β-catenin and TGF-β pathways in established hypertension. Methods: Twelve-month old spontaneously hypertensive (HTN) rats (SHR, n=29) and normotensive Wistar-Kyoto controls (n=8) were studied. SHR group was divided into HTN controls (n=7) and therapy groups: Perindopril (PRD-0.5 mg/kg/day, n=9);

73 S560 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Tranilast (Tran-600 mg/kg bid, n=7); or Perindopril & Tranilast combination (PRD+Tran, n=6) for 4 weeks. Microelectrode array electrophysiology studies, cardiac dimensions and histological parameters were performed and assessed for electrical and structural remodeling. Immunohistochemistry and western blots (n=3 in each group) were performed to examine pro-fibrotic markers. Results: All Perindopril but not Tranilast treated animals demonstrated reduced systolic blood pressure levels. All treated groups demonstrated: improved atrial conduction, reduced AF vulnerability, reduced left ventricular hypertrophy, atrial interstitial fibrosis, myocyte hypertrophy and restored TGFβ1, connexin-43 and endothelin-1 expressions (all p<0.05 vs. HTN). Additionally, combination therapy resulted in greatest improvement in myocyte hypertrophy, endomysial fibrosis and gap junction proteins expressions (p<0.05 vs. single agent treatment). β-catenin and cyclin D1 expression were significantly increased and unchanged respectively in hypertension. Both markers were reversed with Tranilast and combination treatment groups (both p<0.05 vs. HTN). With Perindopril treatment, there was a reversing trend in β-catenin without significance and no reversal in Cyclin D1. Conclusion: Single agent treatment with anti-fibrotic and anti-hypertensives reverses fibrotic substrate for AF via Wnt and TGF-β signaling pathways in established hypertension. Interestingly, an additive effect on reversal of pro-fibrotic markers and structural parameters were seen with combinational therapy. B-PO OBSTRUCTIVE AND CENTRAL SLEEP APNEA HAVE DIFFERENT IMPACTS ON LEFT-ATRIAL ARRHYTHMOGENIC ELECTROPHYSIOLOGY IN PAROXYSMAL ATRIAL FIBRILLATION Yuji Motoike, MD, Masahide Harada, MD, PhD, Asami Fujiwara, Jun Takeda, Masayuki Koshikawa, MD, Tomohide Ichikawa, MD, PhD, Eiichi Watanabe, MD, PhD and Yukio Ozaki, MD, PhD. Fujita Health University, Toyoake, Japan Background: Sleep apnea syndrome (SAS) increases the prevalence of atrial fibrillation (AF), associated with atrial remodeling. SAS was classified into obstructive (OSA) and central types (CSA) with different pathophysiologies. We hypothesized that OSA and CSA affect left atrial (LA) arrhythmogenesis in paroxysmal AF (paf) in different ways. Objective: To examine if OSA and CSA have different impacts on LA remodeling in paf patients. Methods: In 85 paf patients undergoing pulmonary vein (PV) isolation, apnea hypopnea index (AHI) was measured by ambulatory polysomnography (PSG): SAS was defined as AHI>5. CSA was diagnosed when PSG revealed the cessation of airflow at the nose/lips in absence of abdominal movements of rib cage. OSA was diagnosed when the pauses of airflow correlated with labored breathing with abdominal movements of rib cage against the airway pressure. Single extra-stimuli (S1S2, BCL 600 ms) were applied to the left-pv (LPV)/right-PV (RPV)/ coronary sinus (LA) before the procedure: effective refractory periods (ERPs) and conduction time (CT) were measured. S1S2-induced conduction delay (CD) was defined as difference between CT at a BCL and CT at the shortest S1S2 eliciting atrial capture. Results: OSA was diagnosed in 25 patients, CSA in 25 patients, and no SAS in 35 patients (non-sas). CD was significantly increased in OSA vs. non-sas (32±14* vs. 14±12ms, *p<0.05 vs. no-sas). In echocardiography, LA volume index was also increased in OSA vs. non-sas (36±18* vs. 26±8mL/m 2 ), suggesting atrial structural remodeling. LPV-ERP, RPV-ERP, and LA-ERP tended to be shortened in OSA vs. non-sas but the difference did not reach statistical significance (by 10%, 5%, and 6%, respectively). In contrast, LPV-ERP, RPV-ERP, and LA- ERP significantly shortened in CSA vs. non-sas (by 10%*, 8%*, and 8%*, respectively), suggesting atrial electrical remodeling. CD and LA dimension tended to be increased in CSA vs. non- SAS but the difference did not reach statistical significance (28±18 vs. 14±12 ms, and 36±11 vs. 26±8 ml/m 2, respectively). Conclusion: OSA and CSA may have different impacts on LA electrophysiology in paf patients: conduction abnormalities associated with structural remodeling may be predominant in OSA whereas electrical remodeling may be enhanced in CSA. B-PO SLEEP APNEA AND ATRIAL FIBRILLATION: NEW INSIGHTS FROM LONG-TERM SLEEP APNEA MONITORING Dominik K. Linz, MD, PhD, Anthony G. Brooks, PhD, Adrian D. Elliott, PhD, FHRS, Melissa E. Middeldorp, Celine Gallagher, BSN, Jeroen ML. Hendriks, MS, PhD, RN, Rajiv Mahajan, MD, PhD, FHRS, Kadhim Kadhim, MBChB, Mehrdad Emami, MD, Dennis H. Lau, MBBS, PhD, FHRS and Prashanthan Sanders, MBBS, PhD, FHRS. University of Adelaide, Adelaide, Australia, Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia, Centre for Heart Rhythm Disorders, Adelaide, Australia, Centre for Heart Rhythm Disorders, Norwood, Australia, Centre for Heart Rhythm Disorders, University of Adelaide, Sefton Park, Australia, Centre for Heart Rhythm Disorders - University of Adelaide, Adelaide, Australia, Cardiology, Beaumont, Australia, Centre for Heart Rhythm Disorders, University of Adelaide, Adelaide, Australia, University of Adelaide, Unley, SA, Australia, Royal Adelaide Hospital, Cardiology, Norwood, SA, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia Background: In population level studies, the presence of sleep apnea (SA) is associated with increased incidence and prevalence of atrial fibrillation (AF). Objective: To examine the dynamic SA-AF relationship with each patient acting as their own control by simultaneous longterm night-by-night SA and AF monitoring. Methods: Daily data on AF-burden and average respiratory disturbance index (RDI, SA-burden) were extracted from Reply 200 or Kora 100 DR pacemakers in 71 patients. Nightly RDI was grouped into quartiles of severity within each patient. The highest quartile of RDI therefore represented the worst sleep nights for that particular patient. An AF burden of > 1 hour per day was the outcome variable. Results: The mean follow-up per patient was 21 ± 7 weeks, resulting in a total daily monitoring time for the sample of > 28 years (10,355 days). Thirty-two percent (23/71) of patients had a mean RDI of > 20 events/hour, indicative of overall severe SA. 39% (28/71) of patients had > 1 hour of AF on at least one day of their follow-up. Within each patient, the night with the highest RDI (in their highest quartile) conferred a 2.2 fold ( ; P<0.001) increase risk of having at least 1 hour of AF during the respective day. Importantly, this relationship held for both individuals with a high (average RDI >20 events/h) (2.6 fold [ ]; p=0.005) and low (average RDI < 20/h, sub-clinical SA) overall RDI burden (2.1 fold [ ] p<0.001). Conclusion: These data provide the first evidence for a direct relationship between nights with a high RDI and the risk of incident AF on the same day in patients with severe, as well as sub-clinical SA. Not the categorical diagnosis of SA per se, but SA-burden determined as nights with high RDI might be the better metric to quantify SA-severity in patients with AF.

74 Poster Session V S561 B-PO GREATER ATRIAL REMODELLING IN FEMALES WITH ATRIAL FIBRILLATION USING HIGH DENSITY ELECTRO- ANATOMIC MAPPING Geoffrey R. Wong, MBBS, Chrishan J. Nalliah, Aleksandr Voskoboinik, MBBS, Ramanathan Parameswaran, MBBS, MD, Sandeep Prabhu, Bhupesh Pathik, MBBS, Hariharan Sugumar, Liang-han Ling, Geoffrey Lee, MBChB, PhD, Joseph B. Morton, MBBS, PhD, Peter Kistler and Jonathan M. Kalman, MBBS, PhD, FHRS. Royal Melbourne Hospital, Melbourne, Australia, Western Hospital, Elsternwick, Australia, Braybrook, Australia, Alfred Hospital and Baker IDI Heart and Diabetes Institute, Clinical EP and Res, Hughesdale, Australia, Royal Melbourne Hospital, Parkville, Australia, Alfred Hospital & Baker IDI Institute, Melbourne, Australia, Royal Melbourne Hospital, Cardiology, Melbourne, VIC, Australia, Royal Melbourne Hospital, Parkville, VIC, Australia, Royal Melbourne Hospital, Melbourne, VIC, Australia Background: Population studies have shown a higher prevalence of AF in men & risk of stroke in women. Evidence on the impact of gender on atrial substrate is variable. However, there have been no studies reporting gender differences using high-density mapping. Objective: To determine whether there are gender differences in LA substrate using high-density mapping. Methods: 61 consecutive patients with AF underwent electroanatomic mapping of the LA prior to PVI. Confidense algorithm was used to create maps using a multipolar Lasso catheter (Biosense W) during distal CS pacing at 600ms. Each LA was divided into 6 segments. Mean global & regional conduction velocity was determined. Complex signals were manually annotated. Patients with structural heart disease were excluded. Results: In total, 41 patients were male (67%) & 20 were female (33%). Mean age was similar 59±9 vs 62±6yrs. There were significantly more males with persistent AF (25 [62%] vs 8 [40%],p=0.01). Mean LA points was 1253±604pts. The global mean bipolar voltage was significantly lower in females: 1.50±0.35 vs 1.86±0.61mV, p=0.006 (figure). This difference was seen in all 6 segments. Global CV was significantly slower in females (37.7±9 vs 41.4±7cm/s, p=0.04) & global complex fractionated signals were also significantly greater in females (6.9±3.4 vs 4.8±2.7%; p=0.01) with the greatest difference in the posterior wall (9.9±8.5 vs 5.5%±4.3, p=0.05). Conclusion: High density mapping of the LA has revealed more advanced atrial remodelling in females compared with males. These changes may contribute to gender-based differences in the clinical course of females with AF & may in part explain the higher reported risk of recurrence. B-PO EFFECTIVE ATRIAL CONDUCTING SIZE PREDICTS ATRIAL FIBRILLATION VULNERABILITY IN PERSISTENT, BUT NOT PAROXYSMAL, ATRIAL FIBRILLATION Louisa O`Neill, MD, Steven Williams, PhD, Christian Sohns, Andreas Metzner, MD, Bruno Reißmann, MD, John Whitaker, MD, Rahul Mukherjee, MD, James Harrison, MD, PhD, Jaswinder Gill, MD FRCP, Christopher A. Rinaldi, MD, FHRS, Matthew Wright, MD, PhD, Steven Niederer, PhD and Mark O Neill, MD, PHD, FHRS. King s College London, London, United Kingdom, AK-St. Georg, Germany, Asklepios-Klinik St. Georg, Hamburg, Germany, Guys and St. Thomas Hospital, London, United Kingdom, St. Thomas Hospital, Cardiac Dept, London, United Kingdom Background: The multiple wavelet hypothesis is a mechanistic theory to explain the initiation and maintenance of atrial fibrillation (AF) Objective: We hypothesised that if the multiple wavelet hypothesis is valid, the ability of a chamber to support AF would be related to the effective atrial size (EAS), calculated as atrial area divided by wavelength (conduction velocity x refractoriness) Methods: High density mapping followed by pulmonary vein wide area encirclement was performed in patients undergoing 1 st time ablation. Parameters required for EAS calculation were 1) LA body area (A), excluding the isolated pulmonary veins, measured using Carto3; 2) Effective refractory period (ERP), measured at the posterior wall at basic cycle length 600ms; 3) Total activation time (TAT), measured from earliest to latest LA activation; and 4) Global conduction velocity (CV), defined as A/TAT. EAS was calculated as A/(CV x ERP). Post ablation, an AF induction protocol was performed consisting of sensed doubles, sensed triples and incremental atrial pacing. Sustained AF was defined as AF >30s. Results: 39 patients (21 paroxysmal, 18 persistent) were studied. AF was inducible in 14 patients. EAS was significantly greater in patients with inducible vs. non-inducible AF (4.4±1.8cm vs 3.3±1.7cm P=0.035). The difference in EAS was driven by a significant relationship in patients with persistent but not paroxysmal AF (see figure). Conclusion: Effective Atrial Size was associated with AF vulnerability in patients undergoing 1 st time ablation for persistent, but not paroxysmal AF. These data support the multiple wavelet hypothesis only in the population of persistent AF patients studied here. B-PO OBESITY IS ASSOCIATED WITH INCREASED REGIONAL LEFT ATRIAL COMPLEX FRACTIONATED POTENTIALS IN PATIENTS WITH AF Geoffrey R. Wong, MBBS, Chrishan J. Nalliah, Aleksandr Voskoboinik, MBBS, Ramanathan Parameswaran, MBBS, MD, Sandeep Prabhu, Bhupesh Pathik, MBBS, Hariharan Sugumar, Liang-han Ling, Geoffrey Lee, MBChB, PhD, Joseph B. Morton, MBBS, PhD, Peter Kistler, MBBS, PhD, Prashanthan

75 S562 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 Sanders, MBBS, PhD, FHRS and Jonathan M. Kalman, MBBS, PhD, FHRS. Royal Melbourne Hospital, Melbourne, Australia, Western Hospital, Elsternwick, Australia, Braybrook, Australia, Alfred Hospital and Baker IDI Heart and Diabetes Institute, Clinical EP and Res, Hughesdale, Australia, Royal Melbourne Hospital, Parkville, Australia, Royal Melbourne Hospital, Cardiology, Melbourne, VIC, Australia, Royal Melbourne Hospital, Parkville, VIC, Australia, Alfred Hospital & Baker IDI Institute, Melbourne, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia, Royal Melbourne Hospital, Melbourne, VIC, Australia Background: Obesity and increased pericardial fat volume has been linked with left atrial (LA) dilatation & increased risk of atrial fibrillation (AF). Objective: To determine the impact of obesity on LA conduction using high-density, high resolution electroanatomic mapping. Methods: We prospectively enrolled 44 patients with a history of AF to undergo high-density mapping of the LA (mean 1095±763 points per patient) using a multipolar Lasso catheter. Patients were categorized as (1) BMI>30 or (2) BMI<30. Electroanatomic maps were created using the Confidense algorithm (Biosense Webster) during distal coronary sinus pacing at 600 msec cycle length. The LA was divided into 6 regions. Each map was manually annotated for complex signals defined as 3 deflections >50msec duration or 2 separate deflections separated by an isoelectric interval. Results: Mean age was 62±15.2 years, 65% were male, 23 had persistent AF (52%) and 15 were hypertensive (34%). 17 patients were classified as BMI>30 and 27 patients BMI<30. Mean global complex signals percentage was significantly greater in patients with BMI>30 (6±1.1% vs 4.4±0.9%, p=0.04). On regional analysis, increased complex potentials in patients with BMI>30 was seen in all segments, most significantly in the anterior wall (6.7±1.8% vs 2.6±1.1%, p=0.01) (Figure). There was no significant difference in global or regional bipolar LA voltage between groups. Conclusion: Obesity & BMI>30 is associated with significantly greater global LA complex signals and in segments which may contribute to progressive AF substrate. Institute - Intermountain Heart Rhythm Specialists, Murray, UT, Heart Rhythm Specialists, Salt Lake City, UT, Intermountain Heart Rhythm Specialists, Park City, UT, Intermountain Heart Rhythm Specialists; Eccles Outpatient Care Center, Murray, UT Background: Patients with atrial fibrillation (AF) are at an increased risk for developing dementia. During AF cranial perfusion can be negatively impacted by carotid artery disease focally and globally due to negative influence on extracranial artery flow compensation. Objective: To determine if the presence of AF is associated with an increased risk of dementia and stroke/tia in carotid artery disease patients. Methods: A total of 6,786 patients 18 years of age with symptomatic carotid artery disease and no history of dementia were studied and compared by AF status. Subsequent analysis was based upon treatment (stent, endarterectomy). Outcomes included dementia and stroke/tia. Results: The average age of the population was 71.6±12.4 years, 55.6% were male, and 21.1% had AF. AF increased the risk of dementia (HR=1.68, p<0.0001, Figure), stroke/tia (HR=1.33, p<0.0001), and the combination of both (HR=1.45, p<0.0001). However, associations were attenuated after adjustment by risk factors, comorbidities, and medication use (dementia: HR=1.18, p=0.10; stroke/tia: HR=1.13, p=0.08; combination: HR=1.19, p=0.004). In patients that received a carotid stent (n=5,685) dementia rates were 9.4% in the no AF group versus 9.9% in the AF group versus 8.4% in the no AF group and 13.0% in the AF group that received an endarterectomy (n=1,101). Conclusion: AF is associated with augmented dementia risk in patients with carotid artery disease. Dementia risk in AF patients is somewhat attenuated by stent revascularization. These data suggest that AF can unmask cerebral vascular disease resulting in cranial dysfunction. B-PO ATRIAL FIBRILLATION IS ASSOCIATED WITH HIGHER RATES OF DEMENTIA AND STROKE IN PATIENTS WITH CAROTID ARTERY DISEASE Kevin Graves, BS, Heidi T. May, PhD, Victoria Jacobs, PhD, Tami L. Bair, BS, Brian G. Crandall, MD, Michael J. Cutler, DO, PhD, Charles D. Mallender, MD, Jeffrey S. Osborn, MD, CCDS, J. Peter Weiss, MD, John D. Day, MD, FHRS and T. Jared Bunch, MD. University of Utah, Salt Lake City, UT, Intermountain Medical Center, Salt Lake City, UT, Intermountain Heart Rhythm Specialists, Murray, UT, Intermountain Medical Center Heart B-PO WITHDRAWN PAROXYSMAL ATRIAL FIBRILLATION IS ASSOCIATED WITH LEFT ATRIAL MYOPATHY IN HYPERTROPHIC CARDIOMYOPATHY PATIENTS Nestor Vasquez, MD, Benjamin Ostrander, BS, Dai-Yin Lu, MD, Ioannis Ventoulis, MD, PhD, Bereketeab Hailesealassie, MD, MPH, Jeffrey E. Olgin, MD, FHRS, Theodore P. Abraham, MD and Maria R. Abraham, MD. Hypertrophic Cardiomyopathy Center of Excellence, Johns Hopkins University, Baltimore, MD, Stanford School of Medicine, Palo Alto, CA, University of

76 Poster Session V S563 California - San Francisco, San Francisco, CA, Mayo Clinic, Rochester, MN, Johns Hopkins Univ, Baltimore, MD Background: Hypertrophic cardiomyopathy is associated with a high prevalence of atrial fibrillation (AF). There is no consensus on whether AF is a marker or mediator of adverse outcomes in HCM patients. Objective: We tested the hypothesis that AF reflects left atrial (LA) myopathy and is a marker of risk for adverse outcomes in HCM patients. Methods: Echocardiography (2D and speckle tracking) was used to assess LA size/mechanics in a cohort of HCM patients with history of paroxysmal AF (PAF group; n=45) and age/ gender-matched HCM patients without history of AF (No-AF group; n=59). AF was diagnosed by review of EKGs, holter monitor data, ICD interrogation. Patients were followed (mean = 53 months) for development of a combined endpoint (heart failure, all-cause mortality, stroke). Results: Clinical characteristics were similar in the 2 groups; 67% of patients with PAF had a CHADS 2 VASC score 1. The PAF group had higher LA volume, lower LA ejection fraction and higher E/A ratio (reflecting LV diastolic dysfunction) compared to the No-AF group. LA contractile strain and LA reservoir strain were significantly lower in the PAF group (Table1). Male gender, LA reservoir strain and conduit strain (not PAF presence) were associated with development of the composite event outcome in univariate analysis. Only LA conduit strain independently predicted the composite event in a multivariate model. Kaplan Meier survival analysis showed greater composite event-free survival among HCM patients with LA conduit strain > % (p < 0.01). Conclusion: PAF is associated with greater degree of LA myopathy in HCM. LA conduit strain, which reflects LA and LV compliance is a predictor of adverse outcomes in HCM. WITHDRAWN B-PO IMPACT OF PULMONARY VEIN ISOLATION ON NON- DIPPER STATUS AND IMBALANCE OF AUTONOMIC NERVOUS SYSTEM IN PATIENTS WITH PAROXYSMAL ATRIAL FIBRILLATION Tadashi Wada, MD, Takahiro Iida, MD, Takashi Yamada, Mitsutaka Nakashima, MD, Atsushi Mori, MD, Fimi Yokohama, MD, Kenji Kawamoto, MD, Yusuke Katayama, MD, Machiko Tanakaya, MD and Satoru Sakuragi, MD. Iwakuni Clinical Center, Iwakuni, Japan Background: Non-dipping blood pressure (BP) during sleep was frequently found in AF patients. Imbalance of autonomic nervous system (ANS), which has an important role on both initiation and sustainment of atrial fibrillation (AF), is involved in non-dipper status. Objective: In this study, we evaluated the influence of pulmonary vein isolation (PVI) on BP pattern as well as ANS during sleep in AF patients. Methods: We examined consecutive 17 patients (mean age 70±10 years) with paroxysmal AF who underwent PVI with cryoballoon ablation. Measuring heart rate viability (HRV) parameters and 24-h ambulatory BP monitoring (ABPM) were performed before and, 3 and 6 months after PVI. Results: Patients were classified into two groups according to ABPM result: non-dipper group (n=9), dipper group (n=8). In non-dipper group, transition from non-dipper to dipper pattern was found in 7 patients (78%) after PVI. HRV parameters during sleep, especially the parameters of sympathetic activity (Low frequency; LF, and Low-frequency/High-frequency ratio; LF/HF), were also significantly attenuated after PVI (LF; 238±250 ms 2 to 48±45 ms 2, p<0.05, and LF/HF; 1.2±0.6 to 0.8±0.5, p<0.05) in non-dipper group. On the other hand, dipper group had no change in nocturnal BP pattern between before and after PVI. Conclusion: PVI had favorable effect on BP pattern as well as ANS during sleep in patient with AF. B-PO LOCALIZING ROTORS IN HUMAN ATRIAL FIBRILLATION USING DIFFERENTIAL ENTROPY Konstantinos N. Aronis, MD, Susumu Tao, MD, PhD and Hiroshi Ashikaga, MD, PhD, FHRS. Johns Hopkins Hospital, Columbia, MD, John Hopkins University, Baltimore, MD, Johns Hopkins Hospital, Baltimore, MD Background: Rotors sustain atrial fibrillation (AF) and are targeted during AF ablation with variable results. The areas of highest Shannon entropy (ShEn) have been proposed to be a surrogate of rotor location, with limited clinical validation. A possible limitation of rotor localization using ShEn is the discretization of probability distribution of signals obtained from continuous unipolar electrograms. Differential entropy (DE) is a measure of information quantity that does not require discretization of the probability distribution. Objective: To assess rotor localization in human AF using differential entropy (DE). Methods: Using an intracardiac 64-electrode basket catheter, we obtained 77 recordings of 1-minute duration from the atria of 33 patients undergoing ablation for persistent AF. The location of the rotor was marked by a trained electrophysiologist using the Topera system. DE of the continuous unipolar voltage time series was calculated for each electrode using a custom-made MATLAB routine and the location of the global maximum of DE was compared to the location of the rotor. Results: Rotors were present in all 77 intracardiac recordings. The area of maximum DE and rotors overlapped precisely in 9%, and was one electrode away in 36% of the recordings. When the maximum DE was defined as the highest 5 th percentile of DE, the area of maximum DE and rotors overlapped precisely in 22%m and was one electrode away in 59% of the recordings. Last, when maximum DE was defined as the highest 10 th percentile of DE, the area of maximum DE and rotors overlapped precisely in 36%, and was one electrode away in 77% of the recordings. Conclusion: We conclude that DE is a promising metric for rotor localization in human AF, but considering the clinically available spatial resolution of the basket catheter, its accuracy is modest.

77 S564 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO REFRACTORY PERIOD STUDIES PREDICT OBSERVED CYCLE LENGTH OF ADENOSINE SENSITIVE ORGANIZED AREAS: EVIDENCE THAT HUMAN ATRIAL FIBRILLATION IS COMPRISED OF LARGE REENTRANT CIRCUITS Rehan Mahmud, MD, Brittany Janer, PA, Abhijeet Singh, MD and Sharon Hakes, RN, CNP. McLaren Bay Region, Freeland, MI Background: Adenosine sensitive organized activity (ASOA) seen in atrial fibrillation (AF) suggests functional (F) reentry where circuit length would be determined by tissue wavelength (λ) and cycle length (CL) would be equal to the refractory period (RP) of atrial muscle and all conduction must occur in FRP. While short RP and consequently short CL are postulated to underlie AF, the correlation between observed RP and CL of ASOA has not been made. Objective: To correlate the RP with CL of ASOA in at least 2 sites in left atrium (LA), to measure conduction velocity (CV) in FRP of LA in order to determine length of reentrant circuits with the view of determining potential sites of reentry. Methods: FRP was define as effective (E) RP + 10ms. Using a multi-spline catheter, with known inter-electrode distance (D), A1-A2 stimulation was done to determine FRP (ERP+10ms), CV (D T) and electrogram morphology (egm) in FRP, in the right superior pulmonary vein antrum (RSPVA). AF was induced by rapid pacing. Only those patients showing OA simultaneously in both RSPVA and coronary sinus (CS) were included. Twelve mg of Adenosine was given and effect on OA CL in both locations recorded. Results: In 12 patients, the CL of OA accelerated post adenosine from 201 ± 39 ms to 179 ± 38 ms in RSPVA and from 204 ± 36 ms to 182 ± 44 ms. The FRP was 202 ± 18 ms. There was no significant difference between FRP and ASOA CL in RSPVA or ASOA CL in CS. The CV measured during FRP was 0.34 ± 0.11 m/s. The λ (ERP x CV) 66.4 ± 16 mm was substantially similar to circuit length calculated as (CL of ASOA x CV) in RSPVA (71.9 ± 24 mm) or CS (69 ± 18 mm). Conclusion: The FRP and λ predicted the observed CL of ASOA and length of the functional reentry circuit. Acceleration of OA by Adenosine determines that all conduction must occur in FRP, it follows that fractionated electrograms noted in FRP of atrium may mask delineation of such large functional reentry circuits and location of such circuits are only revealed when the electrograms get organized during the course of the circuit. B-PO SAFETE: STROKE AND ATRIAL FIBRILLATION EVALUATION OF THERAPY ELECTRONICALLY Garry Robert Thomas, MD, FRCP, Zana Mariano, MA, Theresa Aves, BSc, Iqwal Mangat, MD, FRCP, Paul Dorian, MD, FRCP and Paul Angaran, MD, FRCP. University of Toronto, Toronto, ON, Canada, St. Michael s Hospital, Toronto, ON, Canada Background: Oral anticoagulants (OACs) decrease stroke rates in atrial fibrillation (AF) by 70%, but large outpatient registry studies have not demonstrated a significant improvement in actual OAC use over the past decade. The pattern of OAC use in teaching hospitals is poorly understood and relies on data from administrative coding. Objective: We assessed the rate of OAC use for AF at our institution using an automated method for data extraction directly from the electronic medical record (EMR). Secondly, we aimed to gain perspective on why some patients, who met guideline indications, were not on an OAC. Methods: This is a retrospective study of 3,915 inpatients at an academic hospital (January December 2014) with at least one 12-lead ECG showing AF. We excluded patients with the following characteristics: i) <65 years old, ii) prosthetic valves, iii) death during admission, iv) absence of discharge summary, and vi) intensive care unit admission at the time of ECG. Patient data was electronically extracted from the Cerner Soarian and GE Muse databases. A sample of 133 patients, randomly selected and equally distributed over the study period, was manually reviewed to validate the accuracy of the automated data extraction and to subsequently investigate reasons for not anticoagulating patients. Results: On average, 50.9±2.3% of patients were discharged on a systemic anticoagulant from This was corroborated by the manual review that showed a mean OAC rate of 56.0%. The remaining patients were on ASA alone (33.1%) or no stroke prevention therapy (16.0%). The most common reasons for not prescribing an OAC included: i) most responsible physicians not recognizing AF on ECG, ii) neglecting stroke prevention in AF management, and iii) deferring OAC decisions to primary care providers. OAC rates were lowest among patients admitted to surgical services (21.7%) and highest on cardiology (64.4%) and neurology (69.2%). Conclusion: Anticoagulation rates in inpatients with AF remain suboptimal. Our approach allowed for an automated, feasible, and accurate review of a large population over a period of time. B-PO DOFETILIDE IN PATIENTS WITH ATRIAL FIBRILLATION AND SEVERE LEFT VENTRICULAR HYPERTROPHY H. Immo Lehmann, MD, Dingxin Qin, MD, Madhurmeet Singh, DO, Evan C. Adelstein, MD, FHRS, Samir F. Saba, MD, FHRS and Sandeep K. Jain, MD, FHRS. Center for Atrial Fibrillation, Heart and Vascular Institute, University of Pittsburgh Medical Center, Pittsburgh, PA, University of Pittsburgh Medical Center, Pittsburgh, PA, Univ of Pittsburgh Medical Center, Pittsburgh, PA, UPP Cardiovascular Institute, Wexford, PA Background: Dofetilide is a class III anti-arrhythmic used for rhythm control in patients with atrial fibrillation (AF), but recommendations limit use to patients without severe left ventricular hypertrophy (LVH). Objective: This study sought to explore all-cause-mortality in patients with severe LVH and AF, treated with off-label use dofetilide. Methods: In this observational study, a cohort of 739 consecutive patients with AF, treated with dofetilide from at the University of Pittsburgh Medical Center was retrospectively analyzed. Patients with an intraventricular septum (IVS) thickness 15mm on transthoracic echocardiography were classified as severe LVH group. Patients with severe LVH were pair-matched in a 1:2 pattern according to sex and age for comparison to a group without severe LVH (IVS<15mm). Incidence of all-cause-mortality on dofetilide was compared between the two groups. Results: Forty patients with severe LVH and 80 patients without severe LVH were included. Seventy-eight percent of patients were male. The median age at start of dofetilide was 64.0 (range: ) years. The mean LVEF was 46±8% in severe LVH vs. 43±13% in non-lvh patients (p=0.11), respectively. Median treatment time on dofetilide in patients with severe LVH was 3.6 (range: ) vs. 3.2 (range: ) years in patients without severe LVH (p=0.60). Kaplan-Meier survival analysis revealed no difference in all-cause mortality between the two groups at five years of follow-up while treated on dofetilide (n=0 in severe LVH on dofetilide vs. n=3 in patients without severe LVH on dofetilide; p=0.55). Conclusion: Patients with severe LVH that were treated with

78 Poster Session V S565 dofetilide did not have higher mortality than patients without severe LVH in this AF cohort. These data support the safety of off-label use of dofetilide for the treatment of AF, even when severe LVH is present. B-PO BLEEDING IS AN ALERT FOR NEW-ONSET MALIGNANCY IN PATIENTS WITH ATRIAL FIBRILLATION RECEIVING NON-VITAMIN K ANTICOAGULANTS Cheng-I Wu, Yu-feng Hu, MD, Yenn-Jiang Lin, MD, PhD, Shih- Lin Chang, MD, PhD, Li-Wei Lo, MD, PhD, Fa-Po Chung, MD, Tze-Fan Chao, Jo-Nan Liao, MD, Ta-Chuan Tuan, MD, Chin- Yu Lin, MD, Chun Chao Chen, Ling Kuo, Hsing-Yuan Li, PhD, Ting-Yung Chang, MD, Quang Minh Hoang, Simon Salim, MD, Vu Van Ba, Jennifer Jeanne B. Vicera, Rubiana Sukardi, Chih- Min Liu, MD, Chieh-mao Chuang, Ting-Chun Huang, Chye Gen Chin and Shih-Ann Chen, MD. Heart Rhythm Center and Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veteran General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital, Taipei, Taiwan, Taipei Veterans General Hospital/Nationa, Taipei City, Taiwan, Taipei, Taiwan, Fellow in Training - Taipei Veteran General Hospital, Taipei, Taiwan Background: Increased anticoagulant-related bleeding was associated with pre-existing malignancies. Objective: Whether anticoagulant-related bleeding could be an alerting sign to unmask the new-onset malignancies remains unclear. Methods: We prospectively recruited 397 patients who received NOACs (non-vitamin K anticoagulants) and followed up the incidence of pre-existing and new-onset malignancy for the mean duration of 2 years. The bleeding events were also recorded and chronologically correlated to diagnosis of newonset malignancy. Results: There were 18 patients who were diagnosed with newonset malignancy 1.6±1.0years after the initiation of NOAC (6 urologic cancers, 7 gastrointestinal cancers, 4 lung cancers, and 1 hematologic cancer). The patients with pre-existing malignancy, and new-onset malignancy were associated with higher incidence of bleeding events (no malignancy, pre-existing, and new onset malignancy: 22%, 33%, 68%, P<0.001). There were a total of 12 bleeding events in the patients with new-onset malignancy. Eleven events (92%) preceded the diagnosis of new-onset malignancy. Among these events, 8 patients received thorough cancer screening which leaded to the diagnosis of early-stage malignancy within 2 months. Among three patients who did not received cancer screening, two were diagnosed as advanced cancer with distal metastasis, 4month and 1.5 years after bleeding events respectively. Compared to those without malignancy, the patients with new-onset malignancy had higher CHA 2 DS 2 VASc score (3.8±1.3 vs. 4.7±1.6, P=0.03) and HASBLED score (1.7±0.8 vs. 2.1±1.0, P=0.095). Conclusion: Bleeding after the initiation of NOACs is an alert for new-onset malignancy in patients with atrial fibrillation and a comprehensive screening of cancer is indicated. B-PO ACCURACY AND USABILITY OF A NOVEL, REAL-TIME REALIZABLE ALGORITHM FOR ATRIAL FIBRILLATION DISCRIMINATION USING PULSE DATA FROM A SMARTWATCH: DATA FROM THE ONGOING MPOWER STUDY Eric Ding, Dong Han, Cody Whitcomb, Syed Khairul Bashar, Oluwaseun Adaramola, MD, Dongqi Liu, MD, Apurv Soni, David D. McManus, MD, FHRS and Ki Chon, PhD. University of Massachusetts Medical School, Worcester, MA, University of Connecticut, Storrs, CT Background: Atrial fibrillation (AF) is a common arrhythmia and cause of stroke. By facilitating long term noninvasive arrhythmia monitoring, smartwatches may help with the early diagnosis and treatment of AF, thereby reducing strokes. Objective: To examine the accuracy and usability of a novel approach to AF detection using a smartwatch. Methods: We enrolled 40 ambulatory adults with cardiovascular disease in an ongoing study of smartwatches for AF detection. Participants wore a smartwatch (Samsung Simband) and performed a series of scripted movements to simulate activities of daily living. Participants completed a brief questionnaire including the Brooke System Usability Scale (SUS) to assess smartwatch usability. We performed a blinded analysis of smartwatch pulse recordings using a real-time realizable AF detection algorithm and compared results to a contemporaneous ECG (gold-standard, manually adjudicated). Results: The average age of participants was 71 (8 SD) years and 40% had AF at the time of the exam. Participants wore the watch for an average of 41 min (17 SD). From 264 noise free pulse segments, 44 (17%) showed AF. The detection algorithm demonstrated excellent sensitivity (0.91), specificity (1.0), and accuracy (0.98) for AF discrimination using 30 sec pulse segments. The smartwatch exhibited good usability for AF detection, with an average SUS score of 70 (14 SD). Conclusion: An arrhythmia discrimination algorithm analyzing smartwatch pulse recordings obtained during activities of daily living exhibited excellent accuracy for AF discrimination. Despite advanced age and high burden of comorbidities, participants found the smartwatch to be usable for AF detection. Performance of the Atrial Fibrillation Discrimination Algorithm Using Pulse Data From A Smartwatch Analysis Method TP TN Sens Spec PPV NPV Acc By patient AF: 8 Sinus: By data segment AF: 44 Sinus: B-PO HIGH-DENSITY MAPPING OF THE THE SUBSTRATE FOR ATRIAL FIBRILLATION IN OBSRUCTIVE SLEEP APNEA: RELATIONSHIP WITH AF PHENOTYPE Chrishan Joseph Nalliah, MBBS, Geoffrey R. Wong, MBBS, Aleksandr Voskoboinik, MBBS, Sandeep Prabhu, Hariharan Sugumar, Ramanathan Parameswaran, MBBS, MD, Troy M. Watts, Alex JA. McLellan, MBBS, Joseph B. Morton, MBBS, PhD, Geoffrey Lee, MBChB, PhD, Peter Kistler, Prashanthan Sanders, MBBS, PhD, FHRS and Jonathan M. Kalman, MBBS, PhD, FHRS. Royal Melbourne Hospital, Melbourne, Australia, Western Hospital, Elsternwick, Australia, Alfred Hospital and Baker IDI Heart and Diabetes Institute, Clinical EP and Res, Hughesdale, Australia, Braybrook, Australia, Royal Melbourne Hospital, Australia, The Alfred Hospital, Melbourne, Australia, Royal Melbourne Hospital, Parkville, VIC, Australia, Royal Melbourne Hospital, Cardiology, Melbourne, VIC, Australia, The Aflred Hospital, Melbourne, Australia, Unviversity of Adelaide, Royal Adelaide Hospital and SAHMRI, Adelaide, SA, Australia, Royal Melbourne Hospital, Melbourne, VIC, Australia Background: Obstructive sleep apnea (OSA) has been associated with atrial fibrillation (AF) and may have important implications for the atrial substrate. The AF substrate in OSA has not been evaluated using contemporary high-density mapping techniques. Objective: To define the AF substrate in patients with OSA

79 S566 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 utilizing high density mapping. Methods: Fifty consecutive patients (60±8y, 28% female) having AF ablation (paroxysmal 30, persistent 20) were recruited. All patents underwent formal overnight polysomnography. Respiratory events were classified based on American Academy of Sleep Medicine criteria. Patients were dichotomized based on an apnea-hypopnea (AHI) index of 20. High density left atrial maps were obtained during paced cycle lengths 600ms from the proximal coronary sinus, using a 20 pole multipolar catheter. Each map comprised of mean of 1365±718 points. Each point was individually analysed and annotated. Results: Twenty patients had OSA and 30 patients did not (AHI: 41±17 vs 10±6, p<0.001). Patients with OSA had lower LA voltages (1.08±0.55 vs 1.37±0.44, p=0.04), more low voltage points (<0.5mV) (30.00±20.36% vs 20.31±11.01%, p<0.04) and more fractionation (7.35±3.14% vs 4.25±2.01%, p<0.001). Conduction velocities were not significantly different between patients with and without OSA. AHI and voltage were linearly correlated (r=-0.31, p=0.03). Sub-group analysis based on AF phenotype revealed differences were most apparent in the paroxysmal AF cohort (LA voltage: 1.08±0.61 vs 1.46±0.43, p=0.04, low voltage: 13.31±18.08% vs 18.24±10.32%, p<0.03 fractionation: 8.54±3.28% vs 3.83±1.79%, p<0.001). Conclusion: High density mapping reveals that OSA is associated with marked atrial remodelling, most apparent in patients with paroxysmal AF. Further work is required to determine the relative benefit of OSA treatment in both AF phenotypes. B-PO PR INTERVAL AND RISK OF NEW ATRIAL FIBRILLATION IN PATIENTS WITH CHA 2 DS 2 VASC SCORE OF 1 OR HIGHER Swati Rao, MD, Juergen Kloo, MD, Matthew Decaro, MD and Daniel Frisch, MD. Thomas Jefferson University Hospital, Philadelphia, PA Background: Atrial fibrillation (AF) is associated with structural remodeling of the atria. Studies have shown that a prolonged PR interval is associated with AF. Objective: Identify the relative risk (RR) of AF development in patients with a CHA 2 DS 2 2VASc score of 1 or higher and a prolonged PR interval. Methods: Of 170,680 patients queried in our institutional ECG database from , there were 26,488 patients identified as AF-free, age 65 and older, and with a PR of 120 ms or greater. Of that cohort, 1171 developed AF in 5 years. Patients with and without AF were matched by PR intervals between 200 to 300 ms. Attributable risk and RR of AF development were calculated. Results: The RR for developing AF was 1.45 for PR intervals 200 to 250 ms (p <0.05). Beyond 250 ms, the correlation was weaker, likely due to fewer patients. The highest correlation of the PR interval and AF occurrence was observed in the 200 to 250 PR interval group [Figure 1]. Conclusion: In this population of patients age 65 and older, as the PR increased from 200 to 300 ms, the risk of developing AF increased linearly. The relative risk was as high as These findings suggest that patients who are 65 and older, and have a CHA 2 DS 2 VASC score of at least 1 for male and 2 for female, who have a PR interval greater than 200 ms should be monitored closely for the development of AF. B-PO EVALUATION OF THE SURGICAL TECHNIQUE AND IMPACT OF EPICARDIAL OPEN-ENDED CLIP ON LEFT ATRIAL APPENDAGE (LAA) EXCLUSION Marc William Gerdisch, MD, John Johnkoski, MD and Mubashir Mumtaz, MD. Franciscan St Francis Health, Indianapolis, IN, Aspirus Heart Institute, Wausau, WI, UPMC Pinnacle, Harrisburg, PA Background: An important concern for surgical LAA exclusion has been peri-procedural bleeding and closure gaps. This has led to several different techniques for LAA elimination. AtriClip, an epicardial clip for LAA exclusion has reported stability and reliable exclusion. The next generation clip, AtriClip PRO V (PRO V), a V-shaped open-ended clip, was developed to further simplify device placement. Objective: A prospective, multicenter, non-randomized, unblinded post-market study was conducted to evaluate if PRO V excludes the LAA and maintains position, without resulting in serious peri and post procedural adverse events. Methods: PRO V devices were implanted in 51 patients (mean age: 67 yrs., 41% female) from 3 sites. TEE was used to assess complete exclusion of the LAA and to measure the LAA stump during the surgical procedure. The majority of surgical approaches were right mini-thoracotomy, in 49% (25/51) cases and sternotomy in, 41.2% (21/51) procedures. At the 30-days follow-up, complete exclusion of the LAA was assessed by contrast penetration of the LAA obtained via CT angiography (CTA). Measurement of the LAA stump was assessed at that time via CTA from the approximated ostium of the LAA to the proximal edge of the clip. Based on TEEs and 3D CTAs, independent physician adjudicators (IPA) provided expert opinion on LAA exclusion and AtriClip migration. Results: Five treated patients did not have 30-days follow-up CTA due to early termination, refusal or death. At 30-days followup, the IPA reported no residual stump/pouch on 86.7% (39/45) [95% CI: 73.2%, 94.9%] and no flow on 97.8% (44/45) [95% CI: 88.2%, 99.9%] patients. The mean ± SD depth (mm) of patients with a residual stump was 4.96 ± 1.17 (Range: 4.2 to 7.3). No serious adverse events were reported and one death unrelated to the device was reported. Conclusion: Left Atrial Appendage (LAA) was successfully excluded in 97.8% patients, without peri or post procedural serious adverse events using the PRO V. B-PO WATCHMAN IMPLANTATION IN PATIENTS WITH VERY HIGH STROKE RISK Erika Hutt, MD, Oussama M. Wazni, MD, FHRS, Walid I. Saliba, MD, FHRS, Bilal Saqi, MD, Amr F. Barakat, MD, Khaldoun G. Tarakji, MD, MPH, FHRS, Mohamed Kanj, MD, Bruce D. Lindsay, MD, FHRS, CCDS and Ayman A. Hussein, MD. Cleveland Clinic Foundation, Cleveland, OH, Cleveland

80 Poster Session V S567 Clinic, Bentleyville, OH, Cleveland Clinic, Cleveland, OH, Cleveland Clinic, Pepper Pike, OH, Cleveland Clinic, Dept of Cardiovascular Medicine, Cleveland, OH Background: The Watchman device is increasingly used for stroke prevention in atrial fibrillation. Little is known about the role of this device in patients with very high stroke risk. Objective: To assess the role of Watchman in patients with CHADSVASC 5. Methods: All patients undergoing Watchman implant at our institution were enrolled in a prospective registry. We included all 104 Watchman recipients with CHADSVASC 5. Results: Median age was 78.5±6.4 years and 56% were male: mean CHADSVASC 5.7±0.9 (quartiles 5-6), mean HASBLED 4.0±1.0 (quartiles 3-5). Indications for implantation were significant prior bleeding in 74%, irreversible bleeding condition in 21% and unacceptable stroke risk alone in 15%. All but 2 patients completed 45 days of anticoagulation: One had retroperitoneal hematoma 30 days post implantant on warfarin and one had intracranial hemorrhage resulting in death (original implant indication was recurrent falls) 10 days post implant on apixaban. Of those who completed 45 days of anticoagulation, 58 (57%) used warfarin and 44 (43%) a novel oral anticoagulant. Transesophageal echocardiogram at 45 days revealed no peridevice leak >5mm or device related thrombosis. At 1 year of follow up, stroke occured in 3 (2.8%) patients at 90, 120 and 270 days after procedure. Conclusion: In a population of patients with mean CHADSVASC of 5.7, Watchman implantation appeared to be efficacious, with a residual annual stroke risk of only 2.8%. In this population, the predicted annual risk of stroke is 12% off anticoagulation and >4% on warfarin. B-PO FALLING SHORT OF GUIDELINES: UPTAKE OF CASCADE GENETIC TESTING IN INHERITED ARRHYTHMIAS Emily Decker, MS, Tom Callis, PhD, Amy Daly, MS, Rebecca Truty, PhD and Matteo Vatta, PhD. Invitae, San Francisco, CA Background: Individuals with a pathogenic variant for an inherited arrhythmia require regular cardiac screening and possible life-saving interventions. Due to this, major professional societies unanimously recommend cascade genetic testing of family members when a pathogenic variant has been identified in an index case (HRS, EHRA, APHRS, ACCF, AHA, PACES, AEPC, CCS, CHRS). Recent studies investigating the uptake of cascade genetic testing in small populations (<60 index) with inherited cardiac diseases have found that 40-66% of families pursued testing (Christian, et al. 2017, Restrepo-Cordoba, et al. 2017, van der Roest, et al. 2009). Objective: In a broad population referred for arrhythmia genetic testing, we aim to elucidate the uptake of cascade genetic testing for inherited arrhythmias and compare to the guidelines for universal family testing. Methods: The total number of positive (pathogenic or likely pathogenic) arrhythmia-causing gene test results for index cases were compiled, along with all family member test results linked to each index case. Results: We identified 542 index individuals with a positive (pathogenic or likely pathogenic) test result in an arrhythmiacausing gene. Family members of 351 (64.8%) of these individuals requested testing for the familial variant from our laboratory. Among these 351 families, 931 individuals pursued testing with 492 (52.8%) having inherited the familial variant. For every positive index case, an average of 1.7 family members pursued cascade testing. In families that utilized cascade testing, an average of 2.65 family members were tested. Family variant testing was more widely used (50.0% [106/212]) when the index individual was younger than 18 years compared to 40.6% (134/330) when 18 years or older. Conclusion: In our large cohort of individuals with a positive genetic test for arrhythmia, the uptake of familial cascade testing is consistent with the upper reported range. However, this does not nearly approach the recommendation for all family members to benefit from cascade testing and illustrates the need for access to specialists via telemedicine, online data sharing platforms for families, and other tools supporting cascade testing. B-PO PATHOGENIC VARIANTS IN FLNC, CTNNA3, AND CDH2 ARE RARE IN NORTH AMERICAN ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY (ARVC) PATIENTS Cynthia A. James, PhD, Brittney Murray, MS, Crystal Tichnell, MS, Nuria Amat, MS, Michael Muriello, MD, Stephen Chelko, PhD, Hugh Calkins, MD and Daniel P. Judge, MD. Johns Hopkins University, Baltimore, MD, Medical University of South Carolina, Charleston, SC Background: The genetic basis of ARVC remains elusive in half of patients. Recently, two genes of the area composita (CTNNA3 - αt-catenin, CDH2 - cadherin-2) were implicated in several ARVC families and truncations in filamin C (FLNC) were reported in a cohort of European patients with left-sided disease. The contribution of these genes to ARVC in North Americans is unknown. Objective: To determine the prevalence of rare variants in FLNC, CDH2, and CTNNA3 in gene elusive index cases enrolled in the Johns Hopkins ARVC Registry. Methods: We sequenced FLNC, CTNNA3, and CDH2 of 107 patients (53% male, 98% Caucasian) who 1) met 2010 Task Force Criteria and 2) had no pathogenic variants in PKP2, DSG2, DSP, DSC2, JUP, TMEM43, SCN5A, or PLN. 21 patients had whole exome sequencing (Illumina HiSeq2000 platform). 86 were sequenced using a custom Agilent 500kb panel. Variants with a minor allele frequency (MAF) >0.001 were excluded. FLNC indels were prioritized. Variants were Sanger confirmed. Results: We identified 4 variants (Table). Case 1 has exerciseinduced VT, right-sided ARVC, and no family history. Cases 2 and 3 were diagnosed after a sibling died. Case 4 presented with syncope and developed biventricular disease. CDH2 p.p679a is present in her affected father and absent in her unaffected sibling. Notably, an ARVC family history was more common in variant carriers (3/4 vs. 14/103; p=0.012). Conclusion: Variants in FLNC, CDH2 and CTNNA3 were uncommon suggesting adding these genes to ARVC sequencing will not substantially improve mutation detection. However, variant carriers disproportionately had a family history highlighting the importance of clarifying pathogenicity for cascade screening.

81 S568 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO EARLY-ONSET ATRIAL FIBRILLATION: GENETIC TESTING UNCOVERS A HIGH RATE OF LOOMING INHERITED CARDIOMYOPATHY William R. Goodyer, MD, PhD, Mary Jackson, Jennifer Wylie, MS, Kyla Dunn, MS, Colleen Caleshu, MS, Allysonne Smith, RN, Anthony Trela, NP, Euan Ashley, Scott R. Ceresnak, MD, CEPS-P, Kara S. Motonaga, MD, Anne M. Dubin, MD, FHRS, CEPS-P and Marco Perez. Stanford University - Lucille Packard Children s Hospital, Palo Alto, CA, Stanford University, Stanford, CA, Lucile Packard Children s Hospital, Palo Alto, CA, Stanford University - Lucille Packard Children s Hospital, Stanford, CA, Stanford University Medical Center, Palo Alto, CA, Stanford University - Lucille Packard Children s Hospital, Palo Alto, CA, Lucile Packard Children s Hospital Stanford, Palo Alto, CA, Stanford Univ, Pediatric Cardiology, Palo Alto, CA Background: Early-onset atrial fibrillation (EAF) has shown strong measures of familial aggregation however genetic testing in patients with AF using targeted arrhythmia panels has demonstrated a low yield for causative variants (9-20%), providing the basis for current guidelines against genetic testing. Notably, AF has been associated with several inherited cardiomyopathies (CM), suggestive of a shared etiology and a potential role for expanded genetic testing in EAF. Objective: Assess the prevalence of rare variation in cardiomyopathy gene panels within a cohort of patients with EAF. Methods: Patients presenting to the Stanford Center for Inherited Cardiovascular Diseases from 2014 to 2017 with confirmed EAF, normal cardiac function, a structurally normal heart by echocardiogram and no other significant comorbidities were included. Exclusion criteria included congenital heart disease or reversible causes. Patients underwent genetic counseling and testing with a clinical genetic panel targeting inherited arrhythmias and CM. Results: Genetic testing in 18 EAF patients (mean age 32 yrs [SD 15]; 83% male) identified at least one rare CM-related gene variant in 89%, with 5 actionable variants deemed likely pathogenic or pathogenic in KCNQ1, TTN and RBM20. Interestingly, 4 of these 5 variants would have otherwise been undetected using a basic arrhythmia panel. Loss of function variations in TTN and missense variations in RBM20 were significantly overrepresented in our cohort compared to Genome Aggregation Database controls (16.7% vs. 1.1% and 16.7% vs. 1.9%, respectively; p< for each). To date, 10 patients have received further evaluation by MRI, with 6 revealing previously unappreciated reduced ventricular function, borderline LV non-compaction or late gadolinium enhancement. Conclusion: In a cohort of early-onset AF, genetic testing revealed overrepresentation of variants associated with cardiomyopathies, supported by subsequent structural findings in some. This implicates EAF as a possible sentinel sign for underlying CM prior to structural changes and argues for thorough evaluation and longitudinal follow up of this unique subpopulation of patients. B-PO DEVELOPMENT OF THE FIRST DEDICATED ON-CALL CARDIOVASCULAR GENETIC COUNSELING SERVICE Tia Gabriela Rill Moscarello, MS, Julia Platt, MS, Euan Ashley and Colleen Caleshu, MS. Stanford Health Care, Stanford, CA, Stanford University Medical Center, Palo Alto, CA Background: Genetics care is increasingly being integrated into cardiology and is typically provided on a referral basis with access limited by the availability of outpatient appointments (a 6-12 week wait in our center). We identified a need for immediate genetics evaluations, such as when time-sensitive treatment decisions depend on genetic testing or family history assessment, or when the patient has traveled a long distance for care. Objective: To describe the development and implementation of a novel on-call cardiovascular genetic counseling service for both inpatient and outpatient care. Methods: Retrospective chart review of all consecutive consults in the initial year (December 1, 2016 to November 30, 2017) of the on-call cardiovascular genetic counseling service. Results: We developed a genetic counselor role dedicated to providing on-demand cardiovascular genetics care. The service was advertised to providers in cardiology who paged the on-call genetic counselor to provide an urgent consult. In its first year, the on-call service saw 41 new inpatients and 30 new outpatients. The majority of consults were requested for cardiomyopathies (40/71, 56%) and arrhythmias (14/71, 20%). Most inpatients (36/41, 88%) and all outpatients (30/30, 100%) were seen the same day the consult was requested or the following business day. The most frequent reason for requesting an immediate outpatient genetics evaluation was distance the patient traveled to see their cardiologist (19/30, 63%). Timesensitive consults included genetic testing and DNA banking before withdrawal of life support and family history assessment in cases of unexplained sudden cardiac arrest or arrhythmias of unclear etiology. The volume of consults increased by a mean of 82% per month over the first 6 months. The total number of providers requesting consults increased from 7 in the first three months to 29 by the end of the first year. Conclusion: Our initial experience with this novel service demonstrates that there is a need for on-demand cardiovascular genetics evaluations and that this need can be met via an on-call cardiovascular genetic counseling service. B-PO CHRONIC CHAGAS CARDIOMYOPATHY AND CARDIAC RESYNCHRONIZATION THERAPY: SURVIVAL ANALYSIS Antonio Da Silva Menezes, MD, PhD. Escola de Ciências Médicas, Farmacêuticas e Biomédicas - PUC Goias, Goiania, Brazil Background: Chagas disease is an important health problem with socioeconomic impact in Latin America. It is estimated that 20% to 30% of those infected by Trypanosoma cruzi will develop chronic Chagas cardiomyopathy, generally progressing to heart failure. Cardiac resynchronization therapy (CRT) can be used in patients with heart failure and electromechanical dysfunction. Objective: The primary endpoint was analysis of the initial response to CRT in chagasic patients and the secondary endpoint was estimation of the survival rate. Methods: This was an observational, cross-sectional, and retrospective study, based on analysis of 50 patient records following CRT pacing device implantation between June 2009 and March Statistical analysis was performed with Pearson s correlation and Student s T-Test and survival analysis was performed using the Kaplan-Meier method, with a significance level of 5% (p<0.05). Results: Results: Of the 50 patients, 56% were male, with a mean age of 63.4±13.3 years, and an average duration of CRT use of 61.2±21.7 months. The mean QRS duration was ±12.4 ms before and ±22.4 ms after therapy (p<0.001). After 6 months of therapy, 34 patients (78%) had a reduction of at least one New York Heart Association functional class (p=0.014).the mean left ventricular ejection fraction was 29±7% before and 39.1±12.2% after use of CRT (p<0.001). The

82 Poster Session V S569 left ventricular end-systolic volume (LVESV) before CRT was 265±19 ml and the mean LVESV after CRT was 112± 13 ml ( p<0.01). The survival rate after 72 months was 45%. Conclusion: This study showed a significant number of responders, but a non- significant survival rate at 72 months in chagasic patients who underwent CRT. B-PO DOES EVERY LEFT BUNDLE BRANCH BLOCK MEAN THE SAME IN CARDIAC RESYNCHRONISATION THERAPY? Antonius van Stipdonk, MD, Iris ter Horst, M.D., Renske Hoogland, BSc, Harry J.G.M. Crijns, Frits W. Prinzen, PhD, Mathias Meine, MD, Alexander H. Maass, MD, PhD and Kevin Vernooy, MD. Maastricht University Medical Centre, Maastricht, Netherlands, University Medical Center Utrecht, Utrecht, Netherlands, Maastricht University Medical Center, Maastricht, Netherlands, Maastricht University, Maastricht, Netherlands, University Medical Center, Cardiologie, Utrecht, Netherlands, University Medical Center Groningen, Groningen, Netherlands, Cardiovascular Research Inst. Maastricht, Maastricht, Netherlands Background: Left bundle branch block (LBBB) morphology is strongly associated with positive response to cardiac resynchronisation therapy (CRT). There are, however, multiple definitions for LBBB, all consisting of a different set of morphological ECG features. Objective: To evaluate the association of LBBB according to different definitions and outcome to CRT and to investigate which morphological ECG features predominantly contribute to this association. Methods: A retrospective multicentre study was conducted in 1,492 CRT patients with a baseline 12-lead ECG available. Patients were classified as LBBB or non-lbbb according to different definitions (ESC, AHA, MADIT, Strauss). Primary endpoint was the combination of all-cause mortality, cardiac transplantation or LVAD implantation. Results: Correlation between classification by different LBBB definitions varied significantly, with AHA standing out as highly specific (panel A). For each LBBB definition there was a significant association with the primary endpoint, with a relative risk reduction ranging from 39 to 43% (panel B). Criteria independently associated to outcome are QS or rs in lead V1, Notch in lead V5-6, I or avl, and absence of a Q in lead V5-6, I, and avl. Conclusion: Patient groups classified as LBBB by different definitions show large differences. Though LBBB patients according to any definition have significantly better outcome to CRT than their respective non-lbbb patients. Each LBBB definition contained redundant morphological criteria, not contributing to the association with outcome. B-PO RIGHT VENTRICULAR PACING IN ICD PATIENTS: ANALYSIS OF DATA FROM 234,332 ICD RECIPIENTS Aleksandre Sambelashvili, PhD, Jodi Koehler, MSc and Peter Eckman, MD. Medtronic Inc., Mounds View, MN, Abbott Northwester Hospital, Minneapolis, MN Background: Chronic right-ventricular only pacing (RVP) may produce ventricular dyssynchrony and is associated with heart failure (HF) exacerbation in patients with left-ventricular systolic dysfunction as shown in DAVID and MOST trials. While there are device algorithms to minimize the percent of RV-paced beats (%RVP), such as Managed Ventricular Pacing (MVP), cardiac resynchronization therapy (CRT) is a class IIa indication for pacing-dependent HF patients. Objective: We investigated the prevalence and reasons for significant %RVP in patients implanted with ICD devices. Methods: We analyzed device data transmitted from 234,332 ICD recipients into the CareLink (Medtronic Inc.) database between 2013 and Based on mean %RVP pacing in the latest transmission patients were dichotomized into %RVP > 40 % and %RVP 40% groups. The two groups were compared with respect to device diagnostic parameters, such as atrial fibrillation (AF) burden, thoracic fluid index, activity and ICD shocks. Results: The proportion of all ICD patients with %RVP>40% declined from 17% in 2013 to 9% in 2017 (Figure). Reasons for %RVP>40% included MVP not programmed on or not available, complete AV block or persistent AF, or heart rate below the device lower rate. Compared to %RVP 40% patients, more patients with %RVP>40% were characterized by daily activity <1 hour over a week (55% vs. 39%), fluid index 60 (53% vs. 50%) and AF 6 hours for at least one day (43% vs 14%). Conclusion: Despite progress in minimizing %RVP, 9.0 % of ICD patients receive %RVP>40% and could be considered for an addition of CRT based on current indications. B-PO SIGNIFICANCE OF MYELOPEROXIDASE AS A PREDICTOR OF CRT RESPONSE Jonas Woermann, MD, Jakob Lüker, MD, Tobias Plenge, MD, Jan-Hendrik van den Bruck, MD, Volker Rudolph, MD, Anna Klinke, PhD, Martin Mollenhauer, PhD, Liz Kuffer, MD, Stephan Baldus, MD, Daniel Steven, MD and Arian Sultan, MD. University Heart Center Cologne, Cologne, Germany, University Cologne Cardiovascular Research Center, Cologne, Germany Background: Cardiac Resynchronization Therapy (CRT) is a well-established treatment option for patients with chronic heart failure (CHF) and left bundle branch block (LBBB). It would be

83 S570 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 desirable to identify patients therapy response prior to device implantation. Inflammation and oxidative stress play a key role in CHF. Previous studies proved the prognostic significance of biomarkers such as myeloperoxidase (MPO) in the setting of CHF. Objective: This study aimed to determine the role of MPO and if changes in MPO levels possibly help to discern CRT responders from non-responders. Methods: Fifty-three patients (age 68±13y; 44 men) underwent successful CRT implantation according to current guidelines. MPO and NT-proBNP levels were determined prior to and 90 days after CRT implantation. Furthermore, a physical capacity test (PC), including a six-minute-walking-test (6-MWT) and NYHA classification level was evaluated at baseline and during follow-up (FU). Results: During FU 3 groups could be discerned according to clinical response (PC, NYHA): 1. Early responding patients (ER) (n=31) showing a significant improvement of PC and NYHA class within 30 days of FU. 2. Late responding patients (LR) (n=3) reported improvement between day 30 and Nonresponding (NR) patients (n=19) with no clinical improvement. In accordance MPO baseline levels differed significantly in all 3 groups. Furthermore, a significant decline of MPO levels after CRT was detectable in the ER and the LR group as compared to baseline levels. The NR group showed the lowest MPO levels at baseline and no significant change over time. For NT-proBNP levels no significant differences were detectable between groups. ROC analysis revealed a MPO cut-off value of 242 ng/ml with a sensitivity of 93.5 % and specificity of 71.4 %. Conclusion: MPO levels prior to CRT implantation are of additional value to predict CRT response and furthermore to specify the timeframe of expected response. However, to determine a robust prospective MPO cut-off value further trials are required. B-PO SKIN SYMPATHETIC NERVE ACTIVITY IS ASSOCIATED WITH MYOCARDIAL INFARCTION AND VENTRICULAR ARRHYTHMIA Wei Chung Tsai, MD, Chang Jen Chen, Hsiang-Chun Lee, Kun-Tai Lee, MD, Hsueh-Wei Yen, Shien-Fong Lin, PhD, FHRS, Peng-Sheng Chen, MD, FHRS and Wen-Ter Lai, MD. Kaohsiung Medical University, Taiwan, Kaohsiung Medical University, Kaohsiung, Taiwan, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, National Chiao-Tung University, Hsinchu, Taiwan, Indiana Univ School of Medicine, Krannert Institute of Cardiology, Indianapolis, IN, Kaohsiung Medical Univ Hospital, Kaohsiung, Taiwan Background: neuecg is a new method of recording and analyzing electrical signals from the skin, then bandpass filters the signals between 500 Hz and 1000 Hz to display skin sympathetic nerve activity (SKNA). Sympathetic overdrive is associated with myocardial infarction (MI) and ventricular arrhythmia (VA). Objective: To test the hypothesis that SKNA recorded by neuecg is increased in patients with MI and the high SKNA is associated with VA in patients with MI. Methods: We recorded neuecg between 9-13 AM in 154 healthy volunteers and 128 patients recovering from acute MI. The neuecg were recorded by conventional ECG electrodes in Lead I configuration (SKNA-I) during baseline, mental arithmetic stress and recovery (5-min for each phase). Data were analyzed to generate the average SKNA (askna, in µv) per digitized sample during the monitoring period. Results: The askna-i at baseline was 1.05 ± 0.35 in the MI group, significantly higher than 0.78 ± 0.23 (p<0.001) in the control group. The askna-i during mental stress was higher in MI group (1.34 ± 0.38) compared with the control group (1.19 ± 0.37, p= ). The recovery phase askna-i were higher in MI group (1.14 ± 0.32), compared with control group (0.83 ± 0.28, p=0.001). Fully reviewed of the ECG monitor during intensive care unit stay were performed from the ninety of 128 patients recovering from MI. Eighteen of the 90 MI patients had ventricular arrhythmias. The VA in MI patients is predicted by the askna-i (odds ratio = 5.3; 95% confidence intervals = (p=0.027)). Conclusion: Patients with MI had higher SKNA than control subjects. SKNA might be useful to predict the VA in MI patients. B-PO THE UTILITY OF A NOVEL VOLTAGE MASS RATIO FOR PROGNOSTICATION OF PATIENTS WITH CARDIAC AMYLOIDOSIS Arul Shanmugam, Muthiah Subramanian, Hisham Ahamed and Navin Mathew. Amrita Institute of Medical Sciences, Kochi, India Background: Although a low electrocardiographic voltage to high left ventricular mass ratio is a hallmark of cardiac amyloidosis, there is limited data on its clinical impact on long term prognosis. Objective: The purpose of this study is to evaluate the prognostic value of the voltage mass ratio in light chain (AL) cardiac amyloidosis. Methods: The data of a 72 consecutive patients with biopsy proven AL amyloidosis with cardiac involvement between 2007 and 2017 was analysed. ECG voltage was assessed in all limb leads, precordial leads, or by Sokolow index, whereas echocardiography derived LV mass (g/m2) was estimated by the Devereux s formula, and the resultant voltage mass ratio was expressed as [mv/(g/m2)]. The primary endpoint was all cause 1 year mortality. Results: Among the 72 patients ( years, males 67%) with light chain cardiac amyloidosis, 32 patients (44.4%) died within 1 year of diagnosis. In comparison to voltage assessments by total precordial leads (HR 0.82, 95% CI , p = 0.321) and Sokolow index (HR 1.04, 95% CI , p = 0.287), the total voltage measured in the limb leads (HR 1.21, 95% CI , p = 0.002) was an independent predictor of the primary endpoint. Furthermore, logistic regression analysis showed that when total limb lead voltage was combined with LV mass, the resultant voltage mass ratio was an independent predictor (HR 1.38, , p < 0.001) of 1 year all-cause mortality. ROC analysis showed that a voltage mass ratio > had good discriminatory power (area under the curve 0.85, 95% CI , p = 0.023) and accuracy (sensitivity 78.1%, specificity 90.1%). In addition, in patients with a voltage mass ratio > 0.010, there was an increased number of hospitalizations for heart failure over 1 year ( vs , p = 0.022). Conclusion: A voltage mass ratio > 0.01 [mv/(g/m2)] accurately identified patients with light chain cardiac amyloidosis at higher risk of 1 year all-cause mortality and heart failure hospitalizations. B-PO ASSOCIATION OF IMPLANTABLE DEVICE MEASURED PHYSICAL ACTIVITY WITH HOSPITALIZATION FOR HEART FAILURE Jacob Patrick Kelly, MD, Nicholas G. Ballew, PhD, Bradley G. Hammill, PhD, Timothy Stivland, Paul W. Jones, MS, Lesley H. Curtis, PhD, Adrian F. Hernandez, MD, Melissa A. Greiner, MS and Brett D. Atwater, MD. Alaska Heart & Vascular Institute, Anchorage, AK, Duke Clinical Research Institute, Durham, NC,

84 Poster Session V S571 Boston Scientific, Arden Hills, MN, Boston Scientific, St. Paul, MN, Duke University Medical Center, Durham, NC Background: Low device measured physical activity (PA) early after implantation of implantable cardioverter defibrillator (ICD) and/or cardiac resynchronization therapy defibrillator (CRT-D) is associated with poor outcomes. Longitudinal PA trajectory may provide early warning before clinical decompensation leading to HF hospitalization or death. Objective: The goal of this study was to evaluate the association of PA level and trajectory with a composite HF hospitalization and mortality endpoint over a 5-year follow-up period following implantation. Methods: We linked daily PA data from the Boston Scientific ALTITUDE dataset of patients with ICD and/or CRT-D implantation to Medicare claims data. Daily PA is continuously counted with any force measurement of 50 milligravities, equivalent to standing up from a seated position. We employed a joint model for the composite endpoint to investigate 1) the hazard associated with the current value of PA and 2) the hazard associated with the current trajectory/slope of PA up to the same time point. We defined current trajectory as the change over the 8 weeks leading up to an activity measurement. Results: Among 20,927 patients, 14.1% and 49.6% experienced the composite endpoint at 1 and 5 years. The mean age was 75.7 years, 26% were female, 67.3% had CRT-D devices, and the median activity level was 1.42 hours per day. Adjusted model results showed that there was a 1.83 (95% confidence interval (CI) = ) fold increase in the hazard of the composite endpoint for 40 minutes of daily PA (median of last PA measurement prior to an event) relative to 85 minutes of PA (median PA measurement across all PA measurements). Similarly, for the PA slope term over 8 weeks, there was a 3.63 (95% CI = ) fold increase in the hazard for a 15% decrease (from 45 to 38 minutes) in activity (median decrease prior to an event) relative to no PA change over 8 weeks. Larger decreases were accompanied with significantly larger hazards. For example, there was a 20.1 fold increase in the hazard for a 33% decrease in PA over 8 weeks. Conclusion: Patients with large slope decreases in PA have significantly higher risk of experiencing HF hospitalization or death. PA data from implantable devices may identify patients before clinical decompensation. B-PO LOCALIZATION OF ACCESSORY PATHWAYS IN PEDIATRIC PATIENTS WITH WOLFF-PARKINSON-WHITE SYNDROME USING 3D RENDERED ELECTROMECHANICAL WAVE IMAGING Lea Melki, MSc, Christopher S. Grubb (co-first), BS, Elaine Wan, MD, Hasan Garan, MD, Eric Silver, MD, FHRS, CEPS-P, Leonardo Liberman (co-senior), MD and Elisa Konofagou, PhD. Columbia University, New York, NY, Columbia University Medical Center, New York, NY, Columbia Presbyterian, New York, NY Background: Electromechanical Wave Imaging (EWI) is a noninvasive imaging modality using a high frame rate ultrasound sequence to visualize cardiac electromechanical activation. This is the first study to utilize EWI in a pediatric population. Objective: Prediction of accessory pathway (AP) location in Wolff-Parkinson-White (WPW) syndrome is frequently based on algorithmic analysis of electrocardiogram (ECG). These algorithms are less reliable in the pediatric population. This study tests the feasibility of using EWI for prediction of AP locations in pediatric patients. Methods: Seven patients with manifest ventricular pre-excitation on resting ECG underwent transthoracic EWI prior to catheter ablation. Catheter mapping of the atrioventricular ring was obtained, and all patients had successful ablations of a single AP. 3D rendered EWI maps were generated and compared to intracardiac mapping and ablation. 12 lead ECG localization used the Boersma et al. algorithm. EWI was blinded to both catheter mapping and 12 lead ECG. Results: Mean age was 13.8±0.1 years old with three male patients. Catheter mapping of the seven patients demonstrated three posteroseptal, two left posterolateral, one left lateral, and one anteroseptal accessory pathways. The Boersma et al. algorithm predicted six of the seven AP locations (86% accuracy). 3D rendered EWI correctly predicted 100% of AP locations. A representative image comparing a left posterolateral AP with the corresponding intracardiac map is shown (Figure 1). Conclusion: EWI was capable of accurately predicting AP locations in pediatric patients with WPW. EWI could serve as a helpful treatment planning tool for these patients. B-PO REAL-TIME MULTI-MODALITY IMAGING APPROACH TO CATHETER ABLATION OF CORONARY CUSP VENTRICULAR ARRHYTHMIAS IN THE PEDIATRIC POPULATION Reina Bianca M. Tan, MD, V. Ramesh Iyer, MD, Tammy L. Sweeten, MS, Christopher M. Janson, MD, CEPS-P, Victoria L. Vetter, MD, MPH, FHRS, R. Lee Vogel, MD and Maully J. Shah, MBBS, FHRS, CEPS-P, CCDS. Children s Hospital of Philadelphia - University of Pennsylvania, Philadelphia, PA, Children s Hospital of Philadelphia, Cardiology, EP, Glastonbury, CT, Children s Hospital of Philadelphia, Philadelphia, PA, Children s Hospital of Philadelphia, Philadelphia, PA, Childrens Hospital of Philadelphia, Philadelphia, PA Background: Catheter ablation (CA) of ventricular arrhythmias (VA) from the right or left coronary cusps (RCC, LCC) is rare in children but can cause life-threatening complications. Objective: To report the use of real-time multi-modality imaging during CA of RCC/LCC VA and effective use of cryoablation (CRYO) as an alternative energy source to enhance procedural safety. Methods: We retrospectively identified patients with structurally normal hearts who underwent CA of VA in RCC or LCC from 6/04-6/17. Real-time imaging included selective coronary angiography (ANGIO), intracardiac echo (ICE) and DynaCT rotational angiography (DCT) to evaluate ablation site proximity to the adjacent coronary ostium. Results: Six patients (5 males, age 15.6 ± 0.8 years), 2 with tachycardia-induced cardiomyopathy (CM) were included. 3D mapping, ANGIO (Fig 1A) and ICE (Fig 1B) were performed in all patients, with DCT in one (Fig 1C). CA was performed using radiofrequency (RF) (n=2) and CRYO (n=4). Site was in RCC (n=2) and LCC (n=4) and confirmed to be > 5 mm from coronary os based on imaging. Successful sites had early fragmented potentials (30-50 ms pre-qrs) and pace mapping morphology match 90% (91-98%). There were no complications noted and post-procedure ANGIO did not show evidence of coronary artery occlusion. Over follow-up of 5.1 ±3.4 years, there were no VA recurrences, aortic insufficiency or evidence of coronary

85 S572 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 ischemia. CM resolved in both patients. Conclusion: Real-time multi-modality imaging provides effective intra-procedural imaging of critical region of the coronary cusp during CA. CRYO is a safe and effective energy source for longterm elimination of VA in the coronary cusp. B-PO LATE ATRIAL ARRHYTHMIAS AFTER CARDIAC TRANSPLANTATION IN CHILDREN: ELECTROPHYSIOLOGY CHARACTERISTICS, CATHETER ABLATION AND OUTCOMES Reina Bianca M. Tan, MD, Kimberly Y. Lin, MD, Tammy L. Sweeten, MS and Maully J. Shah, MBBS, FHRS, CEPS-P, CCDS. Children s Hospital of Philadelphia - University of Pennsylvania, Philadelphia, PA, Childrens Hospital of Philadelphia, Philadelphia, PA Background: Majority of atrial arrhythmias occur in the early postoperative period after orthotopic heart transplant (OHT) and subsequently resolve. Mechanisms and treatment of late atrial tachyarrhythmias (LAT) in pediatric OHT patients are not well characterized. Objective: To define the electrophysiology mechanisms of LAT in a contemporary cohort and to evaluate the role of catheter ablation (CA). Methods: A single center retrospective study was conducted at a tertiary care children s hospital to identify all patients 21 years requiring therapeutic interventions for LAT after OHT from 7/2004 to 7/2017. LAT was defined as any atrial arrhythmia occurring 30 days after OHT requiring either chronic antiarrhythmic medication ( 30 days), DC cardioversion or an electrophysiology study (EPS) and CA procedure. Mechanisms of LAT were determined based on ECG, ambulatory monitoring and/or EPS. Results: A total of 145 patients underwent OHT with 104 (72%) via biatrial anastomosis (BAA) and 41 (28%) via bicaval (BCA) anastomosis. At a median follow-up of 0.9 years ( years), 10 patients (6.9%) developed LAT requiring therapeutic intervention. LAT was more common in BAA compared to BCA (7.7% vs 2.4%). Seven patients (77%) underwent CA and 3 were treated with medications. Six of 7 (85%) with CA had BAA type of OHT. Five macroreentrant atrial tachycardia (ART) circuits and 3 ectopic atrial foci were ablated in the 7 patients. One patient with FAT also had WPW from donor heart with atrioventricular reciprocating tachycardia and a left lateral pathway was ablated. Four ART circuits and all FAT treated with CA involved BAA suture lines with variable conduction between the donor and recipient atrium. In addition, 1 ART involved the cavo-tricuspid isthmus. LAT occurred in only one patient with BCA type of OHT due to incessant inappropriate sinus tachycardia and successful sinus node modification was performed. Overall, CA was successful in 6 (85%) with recurrence of FAT in 1 patient. No complications occurred. Right ventricle biopsy at onset of LAT excluded acute rejection in all. Conclusion: LAT mechanisms after OHT include ART and FAT. Surgical technique of BAA rather than acute rejection may contribute to development of LAT. Catheter ablation is usually successful with low risk. B-PO THE CARDIAC RESTITUTION PORTRAIT IN YOUNG HUMAN HEARTS Michael David Weiland, MD, Alexis Shindhelm and Salim F. Idriss, MD, PhD, FHRS, CEPS-P. Duke University Medical Center Pediatric Cardiology, Durham, NC, Duke University, Durham, NC, Duke Univ Medical Center, Pediatric Cardiology, Durham, NC Background: Restitution is the physiologic adjustment of cardiac repolarization timing as heart rate changes. This relationship is non-linear and has dimensions beyond the welldescribed QT/RR pairing. The Restitution Portrait (RP) was previously developed in cellular, tissue, and animal models to quantify restitution and identify repolarization instability such as the transition to electrical alternans. The RP has not been measured in the young human heart. Objective: Quantify cardiac restitution in children with and without Wolff Parkinson White (WPW) immediately after ablation for SVT using the RMS-ECG RP. Methods: Programmed ventricular pacing was performed using a modified RP protocol in WPW (n=6) and non-wpw (n=11) patients immediately following ablation for SVT (age y, mean = 16 y). All patients had normal cardiac anatomy. The Activation-Recovery interval (ARI) and preceding Recovery- Activation Interval (RAI) were measured in all beats of the composite surface RMS-ECG to generate the RP. Results: RPs were measured for each patient. RPs demonstrated multiple restitution components including dynamic, S1S2, and short term memory (see Figure). At higher pacing rates, increasing ARI variance during short term memory suggests transient repolarization instability. There were no significant differences in dynamic restitution parameters between groups. Conclusion: This is the first study demonstrating multidimensional restitution properties in pediatric patients and evidence of repolarization instability during rapid pacing.

86 Poster Session V S573 B-PO LONG-TERM OUTCOMES OF ICD IMPLANTS IN ADULT CONGENITAL HEART DISEASE PATIENTS: A SINGLE CENTRE EXPERIENCE Vinit Sawhney, MD, Sarah Whittaker-Axon, Holly Daw, Seamus Cullen, Katherine VonKlemperer, Bejal Pandya, Fiona Walker, Martin Lowe and Vivienne Ezzat. St Bartholomew`s Hospital London, London, United Kingdom Background: Sudden Cardiac Death (SCD) due to ventricular arrhythmias (VA) accounts for nearly a third of all deaths in the adult congenital heart disease (ACHD) population. Implantable cardioverter defibrillators (ICD) are effective in preventing SCD. However, there is little evidence to establish the safety and efficacy of ICDs in the ACHD population. Objective: We reviewed the indications and long-term outcomes of ICD implants in our ACHD patients. Methods: Retrospective analyses of all ACHD patients undergoing ICD implants at a single centre. All procedural data, complications and follow-up were prospectively recorded. Appropriate and inappropriate device therapy was recorded over the follow-up period. Results: Over a 5-year period, 30 patients with ACHD had ICD implants. 73% male, mean age 43 (22-67) yrs. Mean age at implant was 41 yrs. Underlying etiology was repaired tetralogy of Fallot (TOF) in 30% patients, Mustard for transposition of great arteries (TGA) in 30%, tricuspid atresia in 7% and other (ASD/VSD/coarctation of aorta/as) in 33%. Vast majority (63%) had secondary prevention devices. Of these 5 patients had OOHCA, 3 presented with syncope and 11 had sustained VA. Acute procedural success was 90% with failed DFT requiring new lead implant in 1, failed CS lead in 1 and heamatoma due to inadvertent arterial puncture leading to a contralateral implant in 1 patient. Over a mean follow-up of 3 years, 8 patients (27%) received appropriate ICD shocks for VA. These included 4 TGA, 2 TOFs, 1 aortic coarctation and 1 Ebsteins patient. Atrial arrhythmias were logged in 63% patients, however, the rate of inappropriate device therapy was small (1 of 30 patients). Late complications were seen in 3 patients (2 A-lead and 1-V displacements requiring re-positioning). All cause mortality over the follow-up period was 30%. Conclusion: At our centre, the majority of ICD implants in the ACHD population are for secondary prevention and in patients with TOF or TGA. Rate of inappropriate therapy is low(<3%) and incidence of major complications (20%) smaller than that reported in the current literature. ICD implants in ACHD population come with a modest risk of complications but are efficacious with a low rate of inappropriate therapy in a carefully selected group of patients. B-PO ACUTE AND LONG-TERM OUTCOME OF RADIOFREQUENCY CATHETER ABLATION FOR ATRIAL TACHYCARDIA IN PATIENTS WITH CONGENITAL HEART DISEASE: A MULTICENTER COHORT STUDY Charlotte Brouwer, MD, Joachim Hebe, MD, Peter Lukac, MD, Steen Buus Kristiansen, MD, PhD, Christian Gerdes, MD, PhD, Jens Cosedis Nielsen, MD, Marta de Riva Silva, MD, Nico A. Blom, MD, PhD and Katja Zeppenfeld, MD, PhD. Leiden University Medical Center, Leiden, Netherlands, Center for Electrophysiology, Bremen, Germany, Skejby Hospital, Aarhus N, Denmark, Skejby Hospital, Aarhus, Denmark, Aarhus University Hospital, Cardiology, Aarhus N, Denmark Background: Atrial tachycardia (AT) radiofrequency catheter ablation (RFCA) outcome in congenital heart disease (CHD) may depend on complexity of prior atrial repair and the acute procedural endpoints. Objective: To asses long-term outcome after RFCA for AT in CHD patients according to complexity of atrial surgical intervention and acute procedural outcome. Methods: Consecutive CHD patients referred for RFCA of AT to 3 high volume referral centers between 2006 and 2016 were included. Patients were classified according to complexity of prior atrial repair: no repair/only cannulation (A); simple atrial repair (B) or complex atrial repair (C). Complete procedural success was defined as non-inducibility + AT termination during ablation and/or bidirectional block along ablation lines for intraatrial reentry tachycardia (IART). Patients were followed for AT recurrence (defined as any documented AT >30 seconds after ablation) and mortality. Results: In 290 patients (42±17 years old, 60% male) 405 ablation procedures were performed (3D mapping systems used in 91%, irrigated or contact force catheters in 85%, transbaffle access in 84%). Group A consisted of 52 patients (18%), group B 156 (54%) and group C 81 (28%). A total of 259 AT were targeted: 135 (52%) CTI-dependent flutters, 85 (33%) IART (of which 66% in the systemic venous atrium) and 37 (15%) focal AT. Complete procedural success was tested in 208 (72%) and achieved in 168 (81%). After a median 18 (IQR 4-41) months follow up after the first procedure, AT recurred in 146 (50%) patients (22 (42%) in group A, 86 (55%) in group B and 38 (47%) in group C, p=0.568). AT-free survival after 21 months was comparable among groups (23 (44%) group A, 42(27%) group B and 52 (36%) group C, p=0.354) and among pts with vs. without tested procedural success (72 (41%) vs. 20 (32%), p=0.489). Conclusion: In CHD pts with AT, CTIDF and right-sided IART are the most common AT mechanisms. Despite achievement of acute procedural success in 81%, long-term outcome is poor independent of the type of prior atrial repair or endpoint definition. However, procedural outcome was not systematically tested in this cohort, which may have resulted in selection bias in endpoint definition. B-PO SAFETY AND EFFICACY OF DRONEDARONE IN ADULTS WITH MODERATE OR COMPLEX CONGENITAL HEART DISEASE Frank J. Zimmerman, MD, Anne Foster, ACNP, David Gamboa and Ira Shetty, MD. Advocate Children s Heart Institute, Oak Lawn, IL, University of Utah, The Heart Institute for Children, Oak Lawn, IL Background: Antiarrhythmic therapy for adults with congenital heart disease (CHD) is often limited due to the risk of proarrhythmia or increased mortality. Dronedarone is a class III antiarrhythmic agent that has been effective for treatment of atrial fibrillation. However, there is an increased risk of stroke, heart failure and death in select patient populations. As such, safety concerns and limited experience have led to cautious use in those with CHD. Objective: The purpose of this study was to assess the safety and efficacy of dronedarone for the treatment of atrial arrhythmias in adults with moderate or complex CHD. Methods: Adults with moderate or complex CHD treated with dronedarone for atrial arrhythmias from at our center were included in this study. Arrhythmia burden, functional status (NYHA class), ECG, ECHO, and transaminase levels were evaluated before, during and after medical therapy. Results: Thirteen adults (ages yrs, mean 37 yrs, 8 females) received dronedarone (400mg BID) for an average of 1.8 yrs (range 3 mos-4 yrs) and total follow-up of 23 ptyears. Initial CHD diagnosis was single ventricle s/p Fontan (5),

87 S574 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 tetralogy of Fallot (3), dtga s/p Mustard (2), dtga/vsd s/p arterial switch (1), complex VSD (1) and Ebstein s anomaly (1). Arrhythmia diagnosis was non-sustained atrial tachycardia (7), intra-atrial reentry tachycardia (3), non-sustained atrial fibrillation (2) and AV node reentry tachycardia (1). Prior to starting medication, systemic ventricular function was normal in 11 and mildly reduced in 2. The functional status was NYHA class 1 in 11 and NYHA class 2 in 2. At last follow-up or at the time of stopping the medication, there was no significant change in systemic ventricular function, ECG parameters (PR, QRS or QTc intervals), functional status or transaminase levels. There were no exacerbations of heart failure and no deaths. Atrial arrhythmia burden was decreased in 11/13 and unchanged in 2/13. There was no increase or new occurrence of atrial or ventricular arrhythmias. Conclusion: Dronedarone use in a select group of adults with moderate or complex congenital heart disease was safe and moderately effective in controlling atrial arrhythmia burden with no occurrence of proarrhythmia, exacerbation of heart failure or death. B-PO PATTERNS OF ATRIAL ECTOPY IN PATIENTS WITH ATRIAL SEPTAL DEFECTS Louisa O`Neill, MD, Steven Williams, MD, PhD, John Whitaker, MD, Iain Sim, MD, Rahul Mukherjee, MD, James Harrison, MD, Justo Julia, MD, Conn Sugihara, MB BS, Jaswinder Gill, MD FRCP, Christopher A. Rinaldi, MD, FHRS, Matthew James Wright, MBBS, PhD, FHRS, Alessandra Frigiola, MD and Mark O Neill, MD, DPHIL, FHRS. King s College London, London, United Kingdom, St. Thomas Hospital, London, United Kingdom, Eastbourne District General Hospital, Eastbourne, United Kingdom, Guys and St. Thomas Hospital, London, United Kingdom, St. Thomas Hospital, Cardiac Dept, London, United Kingdom, St. Thomas Hospital, Cardiology, London, United Kingdom Background: Atrial fibrillation (AF) is common in atrial septal defect patients (ASD) but little is known about the triggers for these arrhythmias. We hypothesised that atrial ectopy in ASD patients would be predominantly right-sided in origin. Objective: To determine the origin of ectopy recorded on continuous Holter monitoring in ASD patients compared to atrial fibrillation (AF) patients with structurally normal hearts. Methods: The origin of atrial ectopic beats was determined by measuring P wave amplitude in three Holter leads and calculating the axis for each ectopic beat. Invasive validation was performed by calculating P wave axes on Holter monitoring during intracardiac pacing from multiple atrial sites. Results: Analysis of Holter monitoring P wave vectors during intra-cardiac pacing across 35 sites demonstrated a vector between 90 and 270 had a 90.5% sensitivity and 85.7% specificity for predicting an ectopic beat of left sided (vs right sided) origin. 189 ectopic beats were analysed in 33 ASD patients (14 male, mean age 50.1±16.9 years). 149 ectopic beats were analysed in 37 control patients (21 male, mean age 61.6±10.5 years). Right sided ectopy accounted for 71.4% of all ectopic beats studied in the ASD population and was significantly more prevalent in the ASD population than in the control population (p=0.003). Conclusion: Right sided ectopy is more prevalent in ASD patients compared to non-achd AF patients. This observation may have implications for arrhythmia intervention strategies in this cohort. Further investigation is required to determine the role of right sided ablation as an adjunctive to pulmonary vein isolation in ASD patients with AF. B-PO PATIENT KNOWLEDGE AND PERCEPTIONS OF FDA DEVICE REGULATION Emily P. Zeitler, Sana M. Al-Khatib, MD, FHRS, CCDS, Rebecca Wiggins and Samuel Sears, PhD. Duke University Hospital, Durham, NC, Duke University Medical Center, Durham, NC, Duke University Medical Center, NC, East Carolina University, Greenville, NC Background: Medical device regulation rarely takes patient preferences into consideration. This may be due, in part, to a poor understanding of patients knowledge and perceptions about device regulation. Objective: (1) To establish baseline understanding of patients knowledge and perceptions about device regulation; (2) To begin to understand patients tolerance for risk in exchange for access to innovative medical devices Methods: We designed and tested a 42-question patient survey to evaluate patients knowledge and perceptions of FDA device regulation. After pilot testing, the instrument was administered to 100 consecutive patients in the Duke cardiac implantable electronic devices clinic. Results: Out of 100 respondents, 60% were male with mean age 73 years +/- 13. Mean time since the most recent implant/ replacement procedure was 3 years (range 0-13 years). Overall, respondents had a modest understanding of the FDA s basic operations and structure, but held common misconceptions about the FDA. For example, 60% of respondents believe that the FDA is completely funded by tax dollars, and 20% of respondents believe that the FDA determines device cost of a device. Trust in the FDA was high; 67% of respondents agreed mostly or strongly with the statement: I trust the FDA. When asked if the US does the best job globally keeping people safe, 64% of respondents agreed mostly or strongly, and 61% of respondents believe Americans have the most access globally to innovative technologies. Most respondents (59%) reported a belief that FDA-approved devices were 100% safe but most respondents (57%) were willing to give up some assurance of safety for access to innovative devices. Finally, 75% of respondents believed that giving up some privacy was acceptable to enable the tracking of implantable devices indefinitely. Conclusion: To engage patients in the process of device regulation, a fundamental understanding of patient s knowledge about and perceptions of regulatory policy is a first step. Currently, patient perceptions of regulatory policy do not always align well with reality and this may be particularly true in regard to the execution of implantable device recalls. More work is needed to understand patient s tolerance for risk in the device innovation process.

88 Poster Session V S575 B-PO THE LEARNING CURVE FOR IMPLANTATION OF PACEMAKERS AND DEFIBRILLATORS AMONG ELECTROPHYSIOLOGY FELLOWS Auroa Badin, MD, Muhammad Rizwan Afzal, MD, Hemant Godara, Diego Alcivar, MD, Rafael Cavalcanti, MD, Toshimasa Okabe, Jaret Tyler, MD, Mahmoud Houmsse, MD, Ralph Sayre Augostini, MD, FHRS, Steven J. Kalbfleisch, MD, FHRS, John D. Hummel, MD, FHRS, Emile G. Daoud, MD, FHRS and Raul Weiss, MD, FHRS, CCDS. The Ohio State University, Columbus, OH, Ohio State University, Dublin, OH, The Ohio State University Wexner Medical Center, Dublin, OH, Ohio State University, Department of Cardiovascular Medicine, Columbus, OH, OSU Div of Cardiovascular Medicine, Columbus, OH, Ohio State Univ, Div of Cardiovascular Medicine, Columbus, OH, The Ohio State University Medical Center, Div of Cardiovascular Medicine, Columbus, OH, Ohio State Univ Medical Center, Div of Cardiovascular Medicine, Columbus, OH Background: It is unknown how long it takes to become more efficient at implanting permanent pacemakers (PPM) and implantable defibrillators (ICD). Objective: To compare procedural time, fluoroscopy time and different segments of the implantation procedure among fellows in different stages of their training. Methods: We retrospectively analyzed a total of 2,555 PPM and ICD De-Novo implantations and 736 pulse generator replacements from 2011 to 2017 in a single institution. 15 fellows who completed two years of formal training were included. They were divided into 5 groups based on experience, each with 50 consecutive procedures as follow: (G1=0-50, G2=51-100, G3= , G4= , G5>200). Results: Procedure duration for generator replacement was reduced with experience: in minutes from G1 to G5 (40.6±18, 38.8±17, 32.1±11, 33.5±11.8, 28.6±7, P<0.001) respectively. For new single lead implants with experience respectively there was a reduction in procedure duration (68.3±10, 66.1±31, 58.6±25, 63.8±8, 58.5±30, P<0.001) and fluoroscopy time (7.5±7, 6.4±5, 6.2±5, 6.3±7, 6.7±6). Similar trends found with new dual lead implants: procedure duration respectively (70.7±25, 66.3±20, 66.1±30, 62.3±30, 60.7±30, P <0.001). Interestingly, time to make generator pocket did not differ among groups after 50 procedures, (18.8±10, 14.5±12, 15.7±20, 14.6±10, 15.5±5, P=0.79). Time to suture leads and pocket continued to improve with experience till 150 procedures and then stayed steady, respectively (35.0±17, 31.4±18, 29.1±15, 26.8±12, 26.0±12, P<0.001) Conclusion: Total procedure and fluoroscopy times were significantly reduced with experience during new PPM and ICD implantation; time to create pocket stayed steady after 50 implants whereas, closing time continued to improve until 150 procedures. B-PO STROKE RISK STRATIFICATION IN INDIVIDUALS WITH ATRIAL FIBRILLATION: HEAD TO HEAD COMPARISON INA POPULATION-BASED STUDY Meytal Avgil Tsadok, PhD, Adi Berliner Senderey, MSc, Orna Reges, PhD, Morton Leibowitz, MD, Balicer Ran, MD, PhD, Moshe Hoshen and Moti Haim, MD. Clalit Health Services, Tel Aviv, Israel, Soroka Medical Center, Cardiology, Kfar-Saba, Israel Background: The risk of stroke in patients with atrial fibrillation (AF) depends on the presence of various risk factors, and different risk stratification scores have been developed to guide clinicians for stroke prevention strategies. Objective: In this study we estimated the area under the curve (AUC) and the net reclassification improvement (NRI) of CHADS 2, CHA 2 DS 2 -VASc and R 2 CHADS 2 in a single, large population-based AF cohort. Methods: This retrospective cohort study is based on the electronic medical records of Clalit Health Services- the largest payer provider healthcare organization in Israel. Data from all Clalit members with first AF diagnosis between 2004 and 2015 were extracted. Demographic and comorbidities data were used to calculate the three risk scores and the performance of the scores to predict stroke outcome (within days post AF diagnosis) was compared using AUC and NRI. Results: Of the 89,213 Clalit members with AF, 53.3% were 75 years and 47.7% were men. The proportions of Clalit members at high risk stratum were 66.2%, 86.7% and 71.1% in the CHADS 2, CHA 2 DS 2 -VASc and R 2 CHADS 2, respectively, with stroke incidence rate of 2.9, 2.4 and 2.8 per 100 person years. AUCs were 0.61 for both CHADS 2 and CHA 2 DS 2 -VASc and 0.59 in R 2 CHADS 2. NRI analyses demonstrated a net improvement of 8.9% (95%CI: 6.0%, 11.0%) when CHA 2 DS 2 - VASc was compared to CHADS 2, while there was a net reduction of 8.3% (95%CI: -5.7%, -11.0%) when R 2 CHADS 2 was compared to CHADS 2. Results of AUC analysis remained similar in subpopulation of AF patients who did not purchased anticoagulation therapy within the first three months after the index date, but NRI analysis demonstrated improvement of 13.2% (95%CI: %) and a net reduction of 12.3% (95%CI: -9.0,-15.7%) when CHA 2 DS 2 -VASc and R 2 CHADS 2 were compared to CHADS 2, respectively. Conclusion: Current stroke stratification scores have comparable but limited ability to predict stroke in members with AF. Stroke prevention strategies may vary depending on the applied stratification. There is a need for a better stroke risk stratification score in patients with AF. B-PO ASSOCIATION OF HEALTHCARE PLAN WITH MEDICATION PRESCRIPTIONS FOR THE TREATMENT OF ATRIAL FIBRILLATION Andrew Young Chang, MD, Mariam Askari, BS, Jun Fan, MS, Paul Heidenreich, MD, P. M. Ho, MD, PhD, Kenneth W. Mahaffey, MD, Aditya J. Ullal, BA, Alexander Perino, MD and Mintu P. Turakhia. Stanford University, Stanford, CA, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, Stanford University, Palo Alto, CA, University of Colorado School of Medicine, Aurora, CO, VA Palo Alto Health Care System, Palo Alto, CA, Stanford Cardiovascular Institute/Stanford University / Veterans Affairs Palo Alto Health Care System, Palo Alto, CA Background: Atrial fibrillation (AF), has widely varying treatments for stroke prevention and arrhythmia management. Some of these therapies are increasingly managed by primary care physicians (PCPs). Objective: We therefore investigated if healthcare plans with PCP gatekeeping for access to specialists are associated with different pharmacologic treatment strategies for the disease. Methods: We examined a commercial pharmaceutical claims database (Truven Marketscan TM ) to compare the prescription frequency of oral anticoagulant (OAC), rate control, and rhythm control medications used to treat AF between patients with PCP-gated health plans (where the PCP is the gatekeeper to specialist referral e.g. HMO, EPO, POS) and patients with non-pcp-gatekeeper health plans (e.g. Comprehensive, PPO, CHDP, HDHP) between 2007 and To control for potential confounders, we calculated adjusted odds ratios using multivariable logistic regression models which incorporated age,

89 S576 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 sex, region, Charlson comorbidity index, CHADS 2 Vasc score, hypertension, diabetes, stroke/transient ischemic attack, prior myocardial infarction, peripheral artery disease, and antiplatelet medication use. We also calculated median time to therapy to determine if there was a difference in time to new prescription of these medications. Results: We found similar odds of oral anticoagulant prescription at 90 days following new AF diagnosis between patients in PCP-gated and non-pcp-gated plans (adjusted OR: OAC 1.006, p=0.84; warfarin 1.054, p=0.08; NOAC 0.815, p=0.001;). We observed similar trends for rate control agents (1.166, p<0.0001) and rhythm control agents (0.927, p=0.03). Elapsed time until receipt of medication was similar between PCP-gated and non-gated groups (OAC 4 ±14 days (interquartile range) vs. 5±16 days, p<0.0001; warfarin 4±14 vs. 5±14, p<0.0001; NOAC 7±26 vs. 6±23, p=0.2937; rhythm control 13±35 vs. 13±34, p=0.8661; rate control 10±25 vs. 11±30, p<0.0001). Conclusion: Pharmaceutical claims data do not suggest PCPgatekeeping of healthcare plan to be a major structural barrier to medications received by AF patients, but may be associated with very small decreases in prescriptions of NOACs. B-PO DIFFERENT OBESITY PARADOX OF ISCHEMIC STROKE WITHOUT AND WITH ATRIAL FIBRILLATION Yong-Soo Baek, MD, Pil-Sung Yang, Tae-Hoon Kim, MD, Jae- Sun Uhm, MD, Hui-Nam Pak, MD, PhD, Moon-Hyoung Lee, Boyoung Joung, MD and Dae-Hyeok Kim. Inha University Hospital, Incheon, Korea, Republic of, Yonsei University Health System, Seoul, Korea, Republic of, Yonsei University College of Medicine, Seoul, Korea, Republic of, Severance Hospital, Seoul, Korea, Republic of, Yonsei Cardiovascular Center and Cardiovascular Research Institute, Seoul, Korea, Republic of, Division of Cardiology, Yonsei University College of Medicine, Seoul, Korea, Republic of Background: A paradoxical relationship between stroke and obesity (also known as the obesity paradox ) in the general population is still controversial. Objective: The aim of this study was to investigate whether the association between general obesity, abdominal obesity and ischemic stroke was different in patients without and with AF. Methods: Total 506,181 adults (mean age 47.7 ± 14.4 years, 253,487 men [50.1%]) without ischemic stroke from Korea National Health Insurance Service database from 2009 to 2014 were evaluated. General obesity and abdominal obesity were assessed with body mass index (BMI) and waist circumference (WC). Results: During a mean follow-up of 3.9 ± 1.3 years, 9,282 participants developed ischemic stroke. In non-af subjects, general obesity decreased the risk of stroke in non-af subjects with adjusted hazard ratio (HR) of 1.17 (95% CI, ) for underweight suggesting obesity paradox. Abdominal obesity increased the risk of stroke with adjusted HR of 1.07 (95% CI, ) for per 1-standard deviation (9.4 cm) increase in WC, and with adjusted HR of 1.12 (95% CI, ) for abdominal obesity. However, in AF patient, general obesity had no association with stroke, and abdominal obesity increased the risk of stroke only in women AF less than 55 years old (adjusted HR 2.20, 95% CI, , p=0.030). Conclusion: Obesity paradox of general obesity was observed in non-af subject, but not in AF patients. However, abdominal obesity increased the risk of stroke without showing obesity paradox in non-af, and middle aged AF women. This result suggests that controversy of obesity paradox of stroke might be related with the proportion of AF population. B-PO EFFECT OF STATIN THERAPY ON NEW-ONSET ATRIAL FIBRILLATION IN GENERAL POPULATION: A NATIONWIDE CENSUS BASED LONGITUDINAL STUDY Yong-Soo Baek, MD, Jong-Il Choi, MD, PHD, Yun Gi Kim, Sukkyu Oh, MD, Hee-Soon Park, M.D, Kwang No Lee, MD, Seung- Young Roh, MD, Dong-Hyeok Kim, MD, Jaemin Shim, MD, Dae-hyeok Kim, MD and Young-Hoon Kim, MD. Inha University Hospital, Seoul, Korea, Republic of, Korea University Medical Center, Seoul, Korea, Republic of, Korea University Hospital, Seoul, Korea, Republic of, Sejong General Hospital, Bucheon, Korea, Republic of, Korea University College of Medicine and Korea University Medical Center, Seoul, Korea, Republic of, Inha Univ Hospital, Incheon, Korea, Republic of Background: Statin is known as an upstream therapy for atrial fibrillation (AF). However, there is still debate whether the use of statins prevents new-onset AF. Objective: We investigated whether statin use could reduce incidence of new-onset AF. Methods: We studied 900,664 adults (mean age 40 ± 17 years, 407,152 women [45.2%]) without AF from Korea National Health Insurance Service database from 2008 to We divided them into two groups by statin treatment (group 1, subjects with statin treatment, n=84,690; group 2, without statin treatment, n=815,974). Incidence of new-onset AF was compared after propensity score (PS) matching (matched variables: age, sex, co-morbidities and all related medications, Standardized Difference of all variables<0.03). Results: During a mean follow-up of 8.4 ± 3.1years, AF developed in 9,136 patients. The overall incidence of AF for follow-up duration was 1.33 per 1,000 person-years. After PS matched, the incidence rate of AF in group 1 and 2 were 4.97( ) and 5.78( ) per 1000 person-years, respectively. In Cox proportional hazards models adjusted by the PS of receiving statin treatment, whereas hypertension (HR 13.25, 95% CI , p<0.001) and diabetes mellitus (HR 1.31, 95% CI , p<0.001) were significantly associated with new-onset AF, statin treatment did not reach statistical significance (HR 0.99, 95% CI , p=0.883). Conclusion: This study showed that, although the incidence of AF was lower in patients on statin use compared to those without statin, statin therapy did not reduce new-onset AF after adjusting relevant risk factors and related all other medications.

90 Poster Session V S577 B-PO B-PO THE REVERSIBILITY OF BRADYCARDIA AS A MANIFESTATION OF MEK INHIBITOR-INDUCED CARDIOTOXICITY Mohammad Al-Sarie, MD, Luai Alhazmi, MD, Mohammad M. Karim, MD, Roland Skeel, MD and Saima Karim, D.O. University of Toledo, Toledo, OH, New York Medical Center, Valhalla, NY, Ochsner Clinic, New Orleans, LA Background: Trametinib is a selective MEK1 and MEK2 inhibitor that improves malignancy free survival among patients with metastatic melanoma. There is currently no available data on bradycardia induced by MEK inhibitors Objective: To highlight bradycardia as a potential reversible side effect of Trametinib Methods: N/A Results: A 48 year-old man with metastatic malignant melanoma presented with weakness and fatigue for one week. On examination, heart rate of 42 beats per minute (bpm), blood pressure of 110/70 with no orthostatic changes. Physical exam was normal. EKG showed sinus bradycardia at 32 bpm. Patient had been on MEK inhibitors Trametinib 2 mg orally once daily and Dabrafenib 150 mg orally twice a day for his metastatic melanoma. Serum electrolytes, TSH, cardiac enzymes, echocardiogram were normal. Exercise treadmill stress test showed adequate chronotropic response. After ruling out other causes of sinus bradycardia, the bradycardia was attributed to Trametinib. A week after stopping the Trametinib, the patient s symptoms improved and heart rate increased to 55. The patient was discharged home with an event monitor. Two weeks after hospital discharge, Trametinib was resumed at a lower dose. Data from the monitor demonstrated an increase in heart rate from average of 52 in one week to 77 in fourth week. Conclusion: While on Trametinib, no other etiology of bradycardia was elucidated and patient s heart improved upon Trametinib discontinuation with resumption at lower dose signifying a reversible etiology. To our knowledge, this is the first reported case of Trametinib induced bradycardia with improvement in heart rate range upon lowering the dose after a brief period of cessation. COMPLEMENTATION OF ATRIAL FIBRILLATION SOURCE LOCATION BY COMBINING SIMULTANEOUS ENDOCARDIAL BASKET AND BODY SURFACE MAPPING: CASE REPORT Miguel Rodrigo, PhD, Andreu Climent, PhD, Ismael Hernandez- Romero, MS, Christopher Kowalewski, Tina Baykaner, MD, MPH, Wouter-Jan Rappel, Maria S. Guillem, PhD, Felipe Atienza, MD, PhD and Sanjiv M. Narayan, MD, PhD, FHRS. UPV, Valencia, Spain, Polytechnical Univ of Valencia, Valencia, Spain, Hospital General Universitario Gregorio Maranon, Madrid, Spain, Stanford University, Palo Alto, CA, Stanford University, Stanford, CA, University of California, San Diego, La Jolla, CA, Universidad Politecnica de Valencia, Valencia, Spain, Hospital General University Gregorio Maranon, Madrid, Spain Background: Ablation of atrial fibrillation (AF) drivers may be an effective therapy for drug refractory AF patients. Intracardiac mapping and non-invasive electrocardiographic imaging (ECGi) may identify AF drivers with different properties, yet they have not been compared in the same patients. Objective: To present 2 cases to study the potential complementation between re-entrant driver location from simultaneous prospective endocardial and non-invasive recordings. Methods: Intracardiac electrograms of 2 paroxysmal AF patients (52/60 years, male) were recorded simultaneously with a 64-pole basket catheter and 52-lead body surface recordings. Activation+phase (FIRM) analysis was used to detect endocardial sources. ECGi signals were reconstructed by using zero-order Tikhonov method and reentrant sources were identified by phase analysis. Map guided ablation was applied prospectively. Results: In Patient #1, endocardial analysis (1.A) revealed 7 sources, 2 near left PVs where ablation terminated AF (1.C). Baskets covered 85% of the atrial wall. ECGi analysis identified 6 of these sources, including the termination site (1.B). In Patient #2 (2.A), endocardial baskets covered 66% of the atrial wall, and revealed 8 sources of which 6 could be ablated. AF did not terminate after source ablation and PVI. ECGi (2.B) revealed 2 AF sources in regions not covered by the basket catheter (LAA) or with poor spatial resolution (PLAW). Conclusion: AF rotational sources can be detected both endocardial and non-invasively, with moderate spatial concordance (Chi 2, p<0.01). Non-invasive mapping can complement basket recordings helping to identify AF sources in anatomies hard to be mapped.

91 S578 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO B-PO A HYBRID APPROACH TO DEVICE IMPLANTATION IN VENOUS OCCLUSION: RETROGRADE VENOPLASTY AND BALLOON GUIDED VENOUS ACCESS Ricardo Hernandez, MD, Salman Arain, MD, Zaka Khan, MD, Justin T. Saunders, MD, FHRS and Anne H. Dougherty, MD, FHRS, CCDS. University of Texas Health Science Center, McGovern Medical School, Houston, TX, Univ of Texas-Houston Medical School, Houston, TX Background: Complex venous obstructions are encountered more frequently by implanting physicians as life expectancy and necessary lead revisions increase in cardiac patients. Venoplasty prior to endovasular lead placement has been shown to be safe and effective. In most previously reported studies, venoplasty was performed antegrade after opening the pocket and checking the existing leads. However, in chronic venous obstruction, obtaining access can still be challenging after venoplasty due to low flow and serial obstructions. In this series of three cases, we present a novel technique for lead implantation in patients with venous obstruction that involves the coordinated efforts of an interventionalist and electrophysiologist. Objective: To demonstrate through this multidisciplinary approach that cardiac devices can be safely and effectively implanted in patients with indications for pacing or defibrillation and challenging venous access due to obstruction. Methods: N/A Results: In our three cases, the initial venogram demonstrated high grade subclavian stenosis and in one case chronic total occlusion of the SVC. First, venoplasty was performed in a retrograde fashion by an interventionalist via femoral access. Next, angiography was performed, confirming the position of the wire and balloon in the true lumen of the vessel. The balloon was then inflated at the desired segment of venous access. Under fluoroscopic guidance the contrast filled balloon was then punctured by the electrophysiologist with the access needle. Deflation of the balloon and release of contrast into the lumen thus confirmed proper intraluminal positioning. The guide wire was then advanced through the needle and the balloon. As the balloon is deflated, the wire becomes snared in the balloon and then retracted further down into the central veins allowing smooth insertion of the venous sheath. Pacing and defibrillating leads were then implanted in the usual fashion. Conclusion: With the increasing prevalence of venous obstruction, venous access and device implantation can be extremely challenging. Our novel approach implementing retrograde venoplasty and balloon directed vascular access can facilitate endovascular device implantation and avoid surgical epicardial lead placement. MITRAL ISTHMUS BLOCK BY LONE ETHANOL INFUSION IN THE VEIN OF MARSHALL Ghassen Cheniti, MD, Nicolas Derval, MD, Anna Lam, MD, Konstantinos George Vlachos, MD, PhD, Claire A. Martin, MA, MBBS, PhD, Arnaud Denis, MD, Thomas Pambrun, MD, Masateru Takigawa, Stephane Puyo, PhD, Antonio Frontera, Takeshi Kitamura, Grégoire Massoullie, MD, Felix Bourier, MD, Josselin Duchateau, MD, MSc, Frederic Sacher, MD, Pierre Jais, MD, Michel Haissaguerre, MD, PhD and Meleze Hocini, MD. Hopital Haut Leveque, Bordeaux, France, Hopital Cardiologique Du Haut-Leveque, Pessac, France, Hôpital Cardiologique du Haut-Lévêque - CHU de Bordeaux, Bordeaux- Pessac, France, Bordeaux, France, Pessac,Bordeaux, France, Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom, CHU Bordeaux, Pessac Cedex, France, Hopital Haut Leveque, Bordeaux, France, Hôpital Haut-Lévêque, 33600, France, LIRYC Institute - Hôpital Haut Lévêque, Pessac Cedex, France, CHU Clermont-Ferrand, Boulogne-Billancourt Cedex, France, Deutsches Herzzentrum, Munich, Germany, IHU-LIRYC, Pessac, France, LIRYC Institute/ Bordeaux University Hospital, Bordeaux, France, Hôpital Haut-Lévêque, Bordeaux, France, Boulogne-Billancourt Cedex, France, CWT Meetings & Events, Mélissa Pernot, Boulogne-Billancourt Cedex, France Background: Mitral isthmus (MI) line is the treatment of choice for perimitral flutters. Classically, it is performed by endocardial ablation followed by epicardial ablation inside the coronary sinus if block cannot be achieved. Ethanol infusion in the vein of Marshall (VOM) is an option to achieve MI block, usually in association with endocardial ablation. We report a case of successful flutter termination and MI line block by lone ethanol infusion in the VOM. Objective: Methods: Results: We present a 74 y.o woman with history of persistent AF. She underwent first ablation including pulmonary vein isolation and defragmentation on the anterior left atrium resulting in AF termination. No ablation at the MI was performed. The patient presented eight months later with an atrial tachycardia. We performed high density mapping using a multipolar basket catheter. The activation map identified a double loop reentry including a roof dependent flutter and a perimitral flutter. The tachycardia changed to a single loop perimitral flutter after roof ablation. An approach of ethanol infusion in the VOM was chosen due to the length of the MI (5cm) and the lack of catheter stability. After selective catheterization, the VOM was occluded using a 2x15mm balloon. A total of 5 cc of ethanol was infused, leading to termination of the tachycardia. LA mapping during pacing from the left atrial appendage confirmed MI block and showed a line of low voltage and double potentials. There were no acute complications. Conclusion: Ethanol infusion inside the VOM is feasible and safe. It may represent a useful alternative to endocardial and epicardial radiofrequency ablation for mitral isthmus line.

92 Poster Session V S579 post implant imaging surveillance. Inappropriate shock on T wave can lead to life threatening arrhythmias B-PO B-PO T WAVE OVERSENSING CAUSING INAPPROPRIATE SHOCK AND VENTRICULAR FIBRILLATION IN A SUBCUTANEOUS ICD RECIPIENT Gurjit Singh, MD, Marc K. Lahiri, MD, Arfaat Khan, MD, Waddah Maskoun, MD, FHRS and Claudio D. Schuger. Cardiac Electrophysiology, Detroit, MI, Henry Ford Hospital, Cardiac Electrophysiology, Detroit, MI, Henry Ford Hospital, Electrophysiology, Detroit, MI, Henry Ford Hospital, Detroit, MI, Henry Ford Hospital/ Wayne State University Background: T wave over sensing (TWOS) is a known phenomenon with trans-venous and subcutaneous ICD systems and various algorithms exist to mitigate TWOS. Objective: To describe importance of proper lead positioning in a subcutaneous ICD system and harmful results of inappropriate shocks Methods: N/A Results: A 73 year old male with hypertension, preserved left ventricular function, idiopathic pulmonary fibrosis and obesity (BMI 34.2) was transferred to our institution for multiple ICD shocks (13) over a period of 2 hours on amiodarone and procainamide infusions. Patient has previously underwent a subcutaneous ICD implantation (2-incision technique) for sustained monomorphic VT (SMVT) programmed with primary vector for sensing. ICD interrogation showed multiple appropriate shocks for SMVT (Figure A) and inappropriate shocks for TWOS with one of the shock on T wave resulting in sustained ventricular fibrillation with successful termination by shock (Figure B). CXR showed significant displacement of ICD lead into the left lateral chest wall (Figure C). EP study revealed a spontaneous SMVT which was not inducible with programmed electrical stimulation and a HV interval of 82 ms. Subcutaneous ICD was extracted and a trans-venous dual chamber ICD was implanted. Patient has remained arrhythmia free on beta-blocker therapy. Conclusion: Inappropriate shocks in subcutaneous ICD recipients could be due to lead malpositioning thus calling for strict attention to details during lead implantation and need for UNUSUAL MICROORGANISMS IDENTIFIED IN CARDIAC IMPLANTED ELECTRONIC DEVICE (CIED) INFECTIONS Ahmed Shahab, MD, Nilarun Chowdhuri, Gaurav A. Upadhyay, MD, FHRS, Andrew D. Beaser, MD, Zaid Aziz, MD, Christopher Isaiah Jones, Roderick Tung, MD, FHRS and Hemal M. Nayak, MD, FHRS. Weiss Memorial Hospital, Chicago, IL, The University of Chicago Medicine, Chicago, IL, University of Chicago Medical Center, Chicago, IL, University of Chicago, Chicago, IL Background: Cardiac Implanted Electronic Device (CIED) infections are an increasing management problem with significant morbidity and mortality. The most common causative organisms are Staphylococcal species however more rare organisms are being identified each day. Objective: We present 2 cases of CIED infections by organisms previously not known to cause implantable cardioverter defibrillator (ICD) lead infections. This will help guide future management of this clinical problem. Methods: N/A Results: An 86 year old gentleman with history of atrial fibrillation and ischemic cardiomyopathy presented with a biventricular ICD device infection. He underwent a total ICD system extraction and was treated empirically with Intravenous Vancomycin and Cefazolin. He was found to have a single ICD lead culture positive for Kucoria spp. with no other organisms identified on device or blood cultures. He was switched to an oral course of dicloxacillin for ten days and was discharged after an uneventful hospital stay on a life vest with plan for reimplantation at a later date. We also present a 52 year old obese gentleman with history of end stage renal disease and non-ischemic cardiomyopathy who presented with a 3.5cm vegetation over his Right Ventricular (RV) ICD lead. He had been receiving intravenous Vancomycin and Cefepime for 12 weeks without success. He underwent extraction of his ICD generator and leads with a partial fragment still left in place. The cultures obtained during the extraction revealed Pantoea sp. And Staphyloccoccus Hemolyticus from the infected RV lead fragment. Both organisms were pan sensitive and the patient was successfully treated after the extraction with oral Trimethoprim-Sulfamethoxazole indefinitely until the remaining ICD lead fragments could be extracted. Conclusion: Occurrence of Pantoea spp. and Kocuria spp.

93 S580 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 infections is sporadic but may represent new pathogens in CIED infection. Further studies evaluating pathogenic potential, antimicrobial sensitivity and predisposing factors is warranted. B-PO REACTIVE PYOGENIC GRANULOMA FORMATION RELATED TO SUBCUTANEOUS IMPLANTABLE CARDIOVERTER DEFIBRILLATOR Benjamin C. Salgado, MD and Brad S. Sutton, MD, MBA, FHRS. University of Louisville, Louisville, KY Background: Chronic inflammatory reactions to transvenous ICDs are well documented in the literature. Objective: We describe a patient with delayed presentation of erythema and pain at the site of his subcutaneous cardioverter defibrillator (SICD) that ultimately required explantation. Methods: N/A Results: A 51-year-old man referred to electrophysiology clinic with a non-ischemic cardiomyopathy (EF 15%), and increasingly frequent, symptomatic PVCs. Gadolinium-enhanced cardiac MRI showed no evidence of arrhythmogenic right ventricular complex. The patient underwent successful ablation of the PVCs in the posterior-septal RVOT and subsequent implantation of a primary prevention SICD (Cameron Health model 1010). His post-operative course was routine until two years later when he developed progressive skin erythema and pain at the generator site, eventually prompting system extraction. Intraoperatively, gross inspection of the ICD pocket showed serosanguinous fluid, inflammatory exudate and numerous erythematous papules that were raised to the touch and friable. No gross purulence was noted, no organisms seen on microscopy and cultures from the pocket remained negative. Surgical pathology of the papules demonstrated fibrous capsule with inflamed granulation tissue consistent with a pyogenic granuloma. Conclusion: Pyogenic granuloma is a reactive inflammatory process with proliferating vascular channels, fibroblastic connective tissue, and scattered inflammatory cells. Rarely, reactive pyogenic granulomas can be found in response to implanted foreign bodies. To our knowledge, this is the first case of reactive pyogenic granuloma from the SICD generator. patients with hypertrophic cardiomyopathy (HCM), and proper screening can prevent oversensing despite significant left ventricular hypertrophy. Invasive treatment for HCM, however, may change the underlying substrate and impact appropriate SICD sensing. Objective: We describe a patient with HCM and SICD that underwent septal myectomy and presented with inappropriate shocks. Methods: N/A Results: A 46-year-old man with mid-cavitary type HCM underwent a SICD implant for primary prevention of sudden death. Despite maximal medical therapy he remained highly symptomatic and underwent septal myectomy a year later. His post-op recovery was uncomplicated except for development of a new left bundle branch block (LBBB). Three months after his procedure, he had multiple ICD shocks. His ECG continued to have LBBB but now with much taller T-wave relative to R-wave compared with previous tracings. Device interrogation showed sinus tachycardia and inappropriate shocks due to T-wave oversensing (TWOS). Device was updated with new ECG template (SMART Pass) and the sensing vector configuration was changed from primary to alternate. TWOS resolved and the patient had no recurrence. Conclusion: To our knowledge, this is the first reported case of inappropriate shock caused by TWOS in a patient with HCM after septal myectomy. In this case, the T-wave vector variation was secondary to new left bundle branch block causing delayed repolarization changes. Close monitoring of SICD sensor settings might be needed up to 3 months after invasive treatment for HCM to avoid inappropriate shocks. B-PO B-PO INAPPROPRIATE SHOCK FROM DELAYED T-WAVE OVERSENSING BY A SUBCUTANEOUS IMPLANTABLE CARDIOVERTER DEFIBRILLATOR AFTER SEPTAL MYECTOMY FOR HYPERTROPHIC CARDIOMYOPATHY Benjamin C. Salgado, MD, Rita Coram, MD, John Mandrola, MD and Rakesh Gopinathannair, MD, FHRS. University of Louisville, Louisville, KY, Baptist Medical Center, Louisville, KY, University of Lousiville, Louisville, IA Background: Subcutaneous implantable cardioverter defibrillators (SICDs) are effective for primary prevention in ATRIAL DECREMENTAL EVOKED POTENTIALS ACCURATELY DETERMINE THE CRITICAL ISTHMUS OF INTRA-ATRIAL RE-ENTRANT TACHYCARDIA Abhishek Bhaskaran, Sigfus Gizurarson, MD, PhD, Andreu Porta-Sanchez, MD, Yawer Saeed, MBBS, PhD, Sachin Nayyar, MBBS, MD, PhD, CEPS-A, CCDS, Stephane Masse, MASC, Karl Magtibay, BENG, MASC, Krishnakumar Nair, MBBS, CCDS and Kumaraswamy Nanthakumar, MD. Toronto General Hospital, Toronto, ON, Canada, Landspitali University Hospital, Reykjavik, Iceland, 200 Elizabeth Street, Toronto, ON, Canada, Peter Munk Cardiac Centre TGH, Toronto, ON, Canada, University Health Network, Toronto, ON, Canada, Univ Health Network, Toronto, ON, Canada, Toronto General Hospital, Cardiology and Electrophysiology, Toronto, ON, Canada, Univ Health Network - Toronto General Hospital, Toronto, ON, Canada Background: We have shown earlier the utility of decremental

94 Poster Session V S581 evoked potential (DEEP) mapping in identifying critical isthmus of scar VT. As intra-atrial re-entrant tachycardia (IART) have similar pathophysiology, DEEP mapping could be useful in identifying critical targets for ablation. DEEP mapping could particularly be useful if the clinical arrhythmia could not be induced during ablation Objective: To assess the utility of DEEP mapping in identifying the IART ablation targets. Methods: N/A Results: Two patients with cc TGA(Transposition of Great Arteries) and previous cardiac surgery were selected for IART ablation using DEEP mapping. For the first patient a 64-electrode array basket was used and for the second patient a duo-decapolar catheter was used for mapping. In sinus rhythm an extra stimulus was introduced at the end of an atrial pacing train and the decremental local potentials were annotated on the electroantomical map. In both patients DEEP mapping accurately localised the critical isthmus where successful ablation could be performed. IART could not be induced thereafter. Conclusion: DEEP mapping is useful in localizing the critical ablation target in IART. Results: The following day, the patient s symptoms were completely resolved. At 1 year, the patient is asymptomatic with stable RA/RV lead pacing/sensing thresholds & no change in PVC burden (4%) or RV pacing (20%). Conclusion: Symptomatic mechanical obstruction of the TV in the absence of significant TS can occur with RA lead prolapse from excessive RA/RV lead slack. Symptom resolution occurred following removal of the RA/RV lead slack guided by ICE without the need of lead extraction. B-PO B-PO RIGHT ATRIAL LEAD PROLAPSE AS A CAUSE OF TRICUSPID VALVE OBSTRUCTION WITHOUT TRICUSPID STENOSIS Gery F. Tomassoni, MD, FHRS, Anthony Marano, MD and Sandeep Duggal, DO. Baptist Health Lexington, Lexington, KY Background: Mechanical obstruction of the tricuspid valve (TV) caused by tricuspid stenosis (TS) is an uncommon complication of pacemaker (PM) implantation. Mechanisms include RV obstruction by thrombus, vegetations & multiple leads or damage to the TV apparatus. We report a case of mechanical TV obstructive symptoms in the absence of TS caused by right atrial (RA) lead prolapse due to excessive RA/RV lead slack. Objective: 69 year old man with a history of PVC s, PAF, & SSS status post DDDR PM implant in 2003 with generator change out in 2012 presented with a 3 M history of DOE with palpitation sensation. Methods: Workup included a remote normal heart catheterization, a normal GXT myocardial perfusion study, and a CXR with no active disease. PM interrogation showed no AF, normal function, & 4% PVCs with 15% RV pacing. Echocardiogram showed normal LV EF with intermittent lead prolapse across the TV. No thrombus, scar, TV regurgitation, or TS was noted. At time of lead extraction, ICE showed RA lead prolapse across the TV in combination with significant RV lead redundancy (Figure 1a). The RA & RV lead slack was removed by simple manual traction. ICE confirmed elimination of RA lead prolapse (Figure 1b). SUCCESSFUL CATHETER ABLATION OF ATRIAL TACHYCARDIA ORIGINATING FROM THE CORONARY SINUS OSTIUM IN A PATIENT WITH A HISTORY OF FONTAN CONVERSION AND DEXTROCARDIA Takumi Yamada, MD and Yung R. Lau, MD. Univ of Alabama At Birmingham, Birmingham, AL, Univ of Alabama At Birmingham, Div of Pediatric Cardiology, Birmingham, AL Background: Catheter ablation of supraventricular tachycardia is challenging in patients with a history of a congenital heart disease (CHD) and surgical repair. Objective: To illustrate successful catheter ablation of atrial tachycardia (AT) in a patient with a complex anatomy associated with complex CHD and surgical repairs. Methods: N/A Results: A 44-year-old man with a history of complex CHD including univentricle, dextrocardia, and situs ambiguous, had undergone multiple cardiac surgeries including modified Fontan, Fontan conversion, removal right atrial (RA) thrombus, and RA reduction. He developed an AT and underwent EP study and catheter ablation. Pre-procedural CT images revealed that the atria could not be reached by a trans-baffle approach after the Fontan conversion. During EP study, a decapolar catheter was placed in the pulmonary artery through the baffle for recording a left atrial electrogram as a reference of 3D mapping. Activation mapping within the atria was then performed with a contact force sensing ablation catheter (ThermoCool SmartTouch, Biosense Webster) through a retrograde transaortic approach during the AT. The activation map revealed a centrifugal activation pattern from the coronary sinus (CS) ostium. A single irrigated radiofrequency application was delivered at this site, resulting in an elimination of the AT. No complications occurred. Conclusion: This case report illustrated successful catheter ablation of a focal AT originating from the CS ostium in a patient with a history of Fontan conversion and dextrocardia.

95 S582 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 the PB. B-PO B-PO IDIOPATHIC VENTRICULAR TACHYCARDIA ORIGINATING FROM THE PARIETAL BAND IN A PATIENT WITH CORRECTED TRUNCUS ARTERIOSUS Krittapoom Akrawinthawong, MD, MSc and Takumi Yamada, MD. University of Alabama at Birmingham, Birmingham, AL, Univ of Alabama At Birmingham, Birmingham, AL Background: Truncus arteriosus (TA) is a rare form of congenital heart disease (CHD) with a single artery arising from the two ventricles which gives rise to both the aortic and pulmonary vessels and a large ventricular septal defect, requiring neonatal surgical repair to restore a normal pattern of blood flow. Ventricular tachycardias (VTs) related to a surgical scar are common in patients with this CHD. Objective: To illustrate successful catheter ablation of VT originating from the parietal band (PB) in the right ventricle (RV) in a patient with a history of corrected TA. Methods: N/A Results: A 27-year-old man with a history of TA and repeated mechanical aortic valve replacements and conduit repair, developed a recurrent hemodynamically stable VT. The VT was refractory to sotalol, and multiple catheter ablations at the outside hospital. He was then referred to our institute. During the electrophysiological study, VT was induced by burst RV pacing on isoproterenol infusion, but it also occurred spontaneously. The mechanism of the VT was suggested to be focal with abnormal automaticity. The VT exhibited a left bundle branch block and left superior axis QRS morphology pattern with a precordial transition in lead V2 and cycle length of 435 msec. Activation mapping during the VT recorded the earliest ventricular activation at the septal aspect of the PB where an excellent pace map was recorded, and no abnormal electrograms such as late and isolated diastolic potentials were recorded. Intracardiac echocardiography and right ventriculogram confirmed the site at the PB. Several irrigated radiofrequency applications were delivered at this site, resulting in an elimination of the VT. Thereafter, no ventricular arrhythmias were induced by any pacing maneuvers on or off isoproterenol infusion. The patient has been free from any ventricular arrhythmias during a follow-up period of more than 6 months. Conclusion: In this case, the VT was likely to be idiopathic, and focal with abnormal automaticity. This case report demonstrated that idiopathic VTs could occur in patients with CHD, and highlighted the significance of anatomical understanding of the PB and challenges in catheter ablation of VTs originating from INAPPROPRIATE SC-ICD SHOCK DUE TO INTERACTION OF RATE RELATED BUNDLE BRANCH ABERRATION AND PECTORAL ELECTRO-MYOPOTENTIALS Pedram Kazemian, Lisa Monahan, DO, Raffaele Corbisiero, MD and Iain Riley. Deborah Lung and Heart Center, Delran, NJ, Deborah Heart and Lung Center, Electrophysiology, Browns Mills, NJ, Boston Scientific, Phoenixville, PA Background: Unlike traditional ICDs in which inappropriate shocks are caused by SVTs/AF in more than 90% of cases, cardiac over-sensing followed by non-cardiac over-sensing account for the majority of cases of inappropriate shocks in patients with SC-ICD. There are no previous case reports that show interaction between cardiac and non-cardiac over sensing resulting in SC-ICD shocks. Objective: This case illustrates the causes of inappropriate shock resulting from interaction between cardiac and noncardiac sources that bypass various filtering and detection algorithms of SC-ICDs. Methods: N/A Results: A 47-year-old firefighter with a diagnosis of nonischemic cardiomyopathy and depressed LVEF underwent implantation of SC-ICD for primary prevention of sudden cardiac death. Baseline ECG showed narrow QRS morphology. One month after his device implantation, he presented to emergency department with multiple ICD shocks that occurred while he was engaged in exercise using his arms and legs without any evidence of syncope or pre syncope. Review of his stored electrograms showed rate dependent change in QRS and T morphology as well as superimposed noise due to electromyopotentials.he underwent treadmill stress testing during which he developed a rate-related left bundle branch block (LBBB) aberrancy at beats per minute. The device filtering algorithms were unable to detect T wave over sensing due to superimposed myo-potential noise. He was subsequently exercised up to his peak exercise capacity with a heart rate of 200 beats per minute. The alternate vector remained unaffected by the changed morphology and was therefore selected. Conclusion: Special exercise testing that simultaneously engages both upper and lower extremities such as elliptical machines might be necessary to evaluate the accuracy of SC- ICDs in discrimination of benign arrhythmias and to screen patients against inappropriate signal detection that arises from the interplay of cardiac and extra-cardiac signals. B-PO ATRIAL FIBRILLATION RESULTING FROM SUPERIOR VENA CAVA DRIVERS ADDRESSED WITH CRYOBALLOON ABLATION Ben Ng, MBBS, FRACP, Rahn Ilsar, MBBS, PhD, Mark McGuire, MBBS, PhD and Suresh Singarayar, MBBS, PhD. Prince of Wales Hospital, Randwick, Australia, Royal Prince Alfed Hospital, Sydney, Australia Background: N/A Objective: N/A Methods: N/A Results: A 74-year-old man presented for pulmonary vein (PV) isolation for paroxysmal atrial fibrillation (AF). The patient was in AF at baseline. Standard applications were made with a 28 mm Arctic Front Advance cryoballoon to each of the 4 PVs. Electrical isolation was confirmed using the Achieve catheter. AF repeatedly appeared to organize, stop and restart

96 Poster Session V S583 following a period of atrial ectopy. Mapping showed early sites for the initiating ectopy within the superior vena cava (SVC). A strategy of SVC isolation with the cryoballoon was undertaken. 3 applications were made at the SVC-right atrial (RA) junction, with vigilant monitoring of diaphragmatic function with phrenic nerve pacing. Following this, pacing verified SVC-RA entry and exit block, and dissociated activity was noted within the SVC, confirming isolation (Fig A). A repeat procedure was undertaken due to recurrent paroxysmal AF 8 months later. All 4 PVs remained isolated from the index procedure. The SVC had reconnected, with voltage and activation mapping tracing the reconnection to the anteromedial aspect of the SVC-RA junction, appearing to correspond with the catheter site for phrenic pacing (Fig B-E), which presumably precluded complete circumferential apposition in the index procedure. Ablations at this site led to reisolation of the SVC. The patient had no documented AF recurrence over 2 years of follow-up. While needed for safety, the pacing catheter itself appeared to hinder circumferential lesion formation. Potential approaches include shifting the catheter between freezes or pacing from a superior access point, such as the internal jugular vein. Conclusion: N/A B-PO A RARE CAUSE OF RIGHT ATRIAL LEAD NOISE Hector L. Banchs, MD, Timm-Michael Dickfeld, MD, PhD, Jeffrey N. Rottman, MD, CCDS, Stephen R. Shorofsky, MD, PhD, FHRS and Vincent Y. See, MD. University of Maryland Program, Baltimore, MD, UMD, Baltimore, MD, Vanderbilt Univ, Nashville, TN, Univ of Maryland Hospital, Division of Cardiology, Baltimore, MD, University of Maryland School of Medicine, Baltimore, MD Background: A method of rate responsive cardiac pacing utilizes minute ventilation (MV) sensors to detect patient activity. In order to achieve this, a small electrical current is applied between the pulse generator and lead electrodes to calculate the transthoracic impedance at any given time. In rare cases, these small impulses may be sensed by telemetric monitoring equipment and appear as artifact. We present a case of a patient with right atrial (RA) lead noise associated with an MV sensor who was referred for lead extraction for suspected RA lead malfunction. Objective: Understand the effects of MV sensors on CIEDs and how pacing algorithms may lead to sensed noise on CIED leads. Methods: N/A Results: A 63 year old woman with history of non-ischemic cardiomyopathy and Boston Scientific Inogen Biventricular ICD (CRTD) implanted 3 years prior was referred for RA lead extraction for intermittent high impedance measurements and lead noise for the past 1 year. RA sensing and pacing thresholds were always normal. The noise was not reproducible by arm or CIED pocket movement or exercises. RV and LV parameters were within normal limits and without noise. Pre-operative interrogation showed multiple episodes of RA lead noise that occurred at regular 50 ms intervals. CRTD system fluoroscopy showed no abnormalities of the leads or lead connections. The manufacturer s technical services reported that the MV sensor transthoracic impendance is measured through the RA lead and could result in lead noise. The MV sensor / respiratory tracking function was turned off understanding that this would not affect resynchronization or tachyarrhythmia therapies. We were able to avoid an unnecessary and potentially morbid lead extraction procedure in this patient. Conclusion: Minute ventilation sensors may be a rare cause of lead noise in certain CIEDs that may be mistaken for lead malfunction. B-PO HALF NORMAL? ABLATION OF A CHALLENGING MITRAL ANNULAR FLUTTER USING AN EXTERNAL IRRIGANT WITH LOW IONIC CONCENTRATION Blake E. Fleeman, MD, Duy Thai Nguyen, MA, MD, FHRS, Nicholas Mantini, MD, Alexis Z. Tumolo, MD, Amneet Sandhu and William H. Sauer, MD, FHRS, CCDS. University of Colorado, Aurora, CO, University of Colorado, Denver, Cardiology, Aurora, CO, University of Colorado, Denver, CO, University of Colorado Hospital, Denver, CO, Univ of Colorado, Denver, CO Background: Use of half-normal saline (HNS) for irrigated tip catheters during radiofrequency ablation (RFA) is a strategy to increase lesion depth. The use of this technique for ablation in the atrium has not been described. Objective: We present a case of successful ablation of recurrent atrial arrhythmias utilizing HNS. Methods: N/A Results: A 65 year old woman with persistent atrial fibrillation (AF) and three prior left atrial ablations presented with recurrent

97 S584 atypical atrial flutter. Prior ablations included pulmonary vein isolation, rotor ablation, an anterior mitral annular (MA) line, CTI line, a roof line and posterior wall isolation. On repeat EP study, high atrial voltage along the superior anteroseptal portion of the MA line was present, despite extensive prior ablation. Entrainment maneuvers and activation mapping during tachycardia were consistent with MA flutter. High powered, external irrigated RFA was performed using normal saline along the prior anteroseptal MA line (Figure). However, ablation was not effective, perhaps due to a cooling effect from the nearby aorta and thicker septal tissue. RFA utilizing HNS was then performed in this area with immediate termination of the tachycardia. Following RFA, no arrhythmias were inducible and bidirectional block across the MA line was confirmed. There were no complications. The patient has remained arrhythmia free on follow up. Conclusion: The use of HNS as an external irrigant during RFA may be a useful strategy in certain situations during ablation of atrial tissue, such as with thick septal tissue or when affected by cooling from nearby vessels. Further studies are needed. Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 the predominant mechanism of VT in patients with cardiac sarcoidosis. Objective: We report a case of Sarcoid VT emanating from a previously unreported site with localized reentry as the mechanism. Methods: N/a Results: A 46-year old male with cardiac sarcoidosis had recurrent VT despite ablations. Patient had no RV or LV endocardial or epicardial scar by voltage mapping. VT with left bundle morphology, inferior axis, late precordial transition (V6) and 280ms cycle length was readily induced by programmed electrical stimulation. As depicted in the figure, while mapping the epicardium during VT with PentaRayTM catheter, we identified a localized area with electrical activity spanning the entire diastolic corridor of VT CL. Fluoroscopically, this region was above the origin of left main artery and LV summit while intracardiac echo demonstrated the area to be in the suprapulmonic epicardium- a rarely reported site for VT (Figure). Irrigated RF ablation resulted in VT termination and noninducibility Conclusion: We report an unusual site and mechanism of Sarcoid VT: suprapulmonic epicardial surface and localized reentry respectively. B-PO LEFT ATRIAL ABLATION IN SETTING OF EXTRACARDIAC AUTOLOGOUS PERICARDIAL TUNNEL FONTAN Rahul Bhardwaj, MD, Tahmeed Contractor, MD, Sudha M. Pai, MD, FHRS and Ravi Mandapati, MD, FHRS, CCDS, CEPS. Loma Linda Medical Center, Loma Linda, CA, Loma Linda University, Loma Linda, CA, Loma Linda Univ Medical Center, Electrophysiology and Cardiology Dept, Loma Linda, CA, Loma Linda University Medical Center, Loma Linda, CA B-PO LOCALIZED REENTRY IN THE EPICARDIAL SUPRAPULMONIC REGION IN A PATIENT WITH SARCOID HEART DISEASE Aditya Saini, MD, Harsimran S. Saini, MD, PhD, Kenneth A. Ellenbogen, MD, FHRS, Jordana Kron and Jayanthi N. Koneru, MBBS, CCDS. Virginia Commonwealth University, Richmond, VA, VCU Medical Center, Richmond, VA, Virginia Commonwealth University, VCU Medical Center, Cardiology, Richmond, VA Background: Scar mediated reentry has been described as Background: Extracardiac Fontan conduit using autologous pericardial flap is an alternative strategy to the traditional Gore-Tex conduit. Extracardiac permanent atrial pacing with lead placement on viable pericardium has been reported. We describe SVT ablation through a pericardial conduit and demonstrate preserved voltage allowing atrial capture on the extracardiac surface of the Fontan. Objective: To demonstrate pericardial transconduit puncture for SVT ablation and presence of extracardiac voltage on atrial aspect of the pericardial conduit Methods: N/A Results: An 11 y. o. girl with double-inlet LV, aortic stenosis, and coarctation of the aorta with Norwood, bidirectional Glenn, and Fontan with an extracardiac lateral tunnel technique using autologous pericardium and LPA stent had symptomatic SVT and was referred for elective EPS and RFA. Atrial pacing was performed from extracardiac conduit in areas with preserved voltage that could be captured. Orthodromic AVRT was induced. A transconduit puncture was performed using fluoroscopic and ICE guidance. Successful ablation of the AP was performed and

98 Poster Session V S585 no further SVT was induced. Conclusion: It is safe to puncture through a pericardial conduit to treat SVT. Bipolar voltage > 0.15mV is present on the extracardiac atrial surface of the Fontan conduit. This finding has implications for placement of extracardiac permanent atrial pacing lead as bipolar voltage map can localize viable targets, particularly for patients unable to have transpulmonary artery puncture due to LPA stent placement. passed thru the recanalized tract. BOB was easily advanced to its standard position in the SVC. The balloon was inflated with 30ml of diluted contrast without any difficulties. The achievement of complete occlusion of the SVC was confirmed on fluoroscopy (image C). Following that, we proceed with the extraction of the older leads. Conclusion: The compliant Bridge Occlusion balloon can be deployed after recanalization of the central venous system. B-PO B-PO DEPLOYMENT OF THE BRIDGE OCCLUSION BALLOON IN COMPLETELY OCCLUDED SUPERIOR VENA CAVA Mohamed Homsi, MD, FHRS, Stacey Swartz, RRT and Mithilesh K. Das, MD. SJHS/Midwest Cardiology, Mishawaka, IN, SJHS/, Mishawaka, IN, Krannert Institute of Cardiology, Indianapolis, IN Background: Patency of superior vena cava (SVC) is critical to be able to use the Bridge Occlusion Balloon (BOB). Objective: To report a case where deployment of BOB became feasible after recanalization of SVC during lead extraction. Methods: NA Results: 38 year old woman with long QT syndrome who received a dual chamber pacemaker in 1994 which was upgraded to dual chamber ICD in The ICD lead was abandoned in 2004 and a new ICD lead (Fidelis 6949) was implanted. Patient presented to our institution with recurrent ventricular fibrillation episodes which were all treated successfully by the defibrillator. Device interrogation showed that the device reached elective replacement interval. There was evidence of noise on both RA and RV leads. After discussion, the patient elected for lead extraction and implantation of subcutaneous ICD. As preparation for the BOB, a guiding wire was advanced from the right femoral vein but it could not be advanced beyond the SVC-RA junction. Angiogram from inferior and superior approach showed complete occlusion at the level of SVS-RA junction (image A). The Fidelis lead was extracted using the GlideLight Laser sheath (14FR) which resulted in recanalization of the SVC (image B). The guiding wire was AN UNUSUAL CASE OF TORSADES DE POINTES Sandeep Arora, MD, FHRS. Excela Health Cardiology, Greensburg, PA Background: Torsades de Pointes is a potentially lethal ventricular arrhythmia associated with prolonged QT interval. We present an usual form of drug induced Torsades de Pointes resulting in cardiac arrest. Objective: To highlight the importance of loperamide induced arrhythmia Methods: N/A Results: A 28-year-old man was admitted due to generalized fatigue for past few weeks. He denied any palpitations or syncope. He had past history of narcotic drug abuse but denied any recent drug use. He was taking Loperamide for irritable bowel syndrome as needed. On examination, pulse rate was 44 b/min with normal blood pressure. Rest of examination was unremarkable. EKG revealed sinus bradycardia with wide bizarre inverted T wave with prolonged QTc of 511ms (Figure). Blood work showed normal metabolic panel, cardiac troponin, thyroid profile and negative Lyme s serology. 2D-Echocardiograpgy and cardiac MRI were normal with normal LVEF. Following day, he developed Torsades de Pointes resulting in cardiac arrest and was successfully resuscitated by external cardioversion. He admitted to consuming high doses of loperamide ( tablets) day. He was treated conservatively and his QTC interval and heart rate improved gradually and was discharged home in stable condition. Conclusion: Our case represents an important and growing problem of drug abuse of over the counter loperamide with potential lethal consequences. It is a synthetic µ-opioid agonist that can prolong QT interval by inhibiting rectifier potassium channel. It is often used for euphoric purposes and for alleviation of opioid withdrawal symptoms. With current ongoing opioid epidemic, loperamide should be used judiciously.

99 S586 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO B-PO PROCAINAMIDE TO UNMASK LATE POTENTIALS IN BRUGADA SYNDROME IN AREA OF NORMAL EPICARDIAL VOLTAGE Scott Koerber, DO, Daniel Cobb, MD, Thomas Turnage, John G. Kpaeyeh, Jr., Medical Doctor, Frank A. Cuoco, MBA, MD, MSBME, FHRS, Michael R. Gold, MD, PhD, FHRS and Jeffrey R. Winterfield, MD, FHRS. Medical University of South Carolina, Charleston, SC, Medical Univ of South Carolina, Cardiology, Mount Pleasant, SC, Medical Univ of South Carolina, Charleston, SC, Medical University of South Carolina, Mount Pleasant, SC Background: Brugada syndrome is a genetically inherited disease associated with ventricular fibrillation (VF) in the absence of structural heart disease. The mechanism of the arrhythmogenic substrate remains unclear, and both depolarization and repolarization abnormalities have been implicated. Late potentials (LP) within areas of slow conduction in the right ventricle (RV) have been targeted for substrate modification in Brugada syndrome. Objective: To describe myocardial voltage in areas around late potentials in Brugada Syndrome. Methods: NA Results: A 37-year-old male with a PMH of Brugada syndrome (Type I ECG pattern) underwent electrophysiology study following a VF arrest. RV endocardial voltage was normal. Epicardial voltage revealed small areas of scar. (Figure 1) A high-density substrate map of the RV epicardium was obtained before and after an IV procainamide infusion (10 mg/kg). (Figure 1) Initially, small diffuse areas of LPs (blue in figure 1) were identified. Following procainamide, a cluster of LPs was unmasked in the basal anterior RV, remote from the scar and in an area of normal voltage. The LPs were targeted for radiofrequency ablation. Following ablation, the area of dense LPs was homogenized. The initial type1 ECG abnormality was no longer present following ablation. Conclusion: Procainamide can be used to unmask arrhythmogenic substrate in Brugada syndrome. In this patient, LPs were identified in normal myocardium. The normalization of the ST elevation following ablation along with the location of LPs in normal voltage suggests a repolarization abnormality rather than an abnormal conduction mechanism. FEASIBILITY OF LEFT ATRIAL ABLATION THROUGH AN INTERATRIAL SEPTAL SHUNT DEVICE: A CASE REPORT Kamal R. Joshi, MD, Petr Neuzil and Vivek Y. Reddy, MD. Mount Sinai Medical Center, Cardiac Electrophysiology, New York, NY, Prague, Czech Republic, Icahn School of Medicine at Mount Sinai, New York, NY Background: An increasingly-used novel interatrial septal shunt device (IASD) is percutaneously implanted in the interatrial septum to reduce LA pressure in HFpEF. This nitinol device with 19mm outer diameter produces a permanent 8mm septal communication. Atrial fibrillation (AF) is not an uncommon arrhythmia in HFpEF patients, and may require treatment in patients who have received an IASD. Objective: We report a HFpEF patient with a prior MAZE in whom an IASD was implanted and subsequently required ablation for AF. Methods: N/A Results: A 70-year old female with coronary artery disease, persistent AF, LVEF 60%, prior CABG and Maze procedure developed recurrent heart failure symptoms. She underwent an IASD implant for HFpEF (NYHA class III). Following IASD implantation, she had recurrence of AF needing DC cardioversion; catheter ablation for AF was planned 7 months later. Two transseptal sheaths were maneuvered through the IASD; a circular mapping catheter and ablation catheter were advanced to the LA. Three of 4 PVs were electrically reconnected. Successful re-isolation of all PVs was achieved. The patient had an uncomplicated hospital course, and no AF recurrence in follow-up (1 year). Conclusion: Transseptal access for left atrial ablation procedures can be safely performed through the IASD. This has important implications in the management of HFpEF patients where effective therapies are lacking.

100 Poster Session V S587 B-PO B-PO A MOST UNUSUAL LOCATION FOR A CORONARY SINUS OSTIUM Sanjaya K. Gupta, Randall Thompson, MD and Rigoberto Ramirez, BA, MD. St. Luke s Hospital of Kansas City, Lee s Summitt, MO, Overland Park, KS Background: Inability to cannulate the coronary sinus occurs in 5-10% of cardiac resynchronization therapy (CRT) device cases, typically due to a Thebesian valve or anatomic variants of the coronary sinus. These variants include unroofed coronary sinus, coronary sinus ostial atresia with drainage via a left persistent superior vena cavae, and fistula of the coronary sinus with the pulmonary veins, pulmonary artery, coronary arteries and hemiazygous and azygous veins Objective: To describe the various coronary sinus anomalies that complicate CRT placement. Methods: N/A Results: A 70 y/o male with a history of nonischemic cardiomyopathy with ejection fraction 45%, a PR interval of 205 msec, a Left Bundle Branch Block with a QRS duration of 152msec and NYHA Class II heart failure symptoms underwent attempted biventricular pacemaker placement. The right atrial and ventricular leads were placed easily, however the coronary sinus could not be cannulated despite extensive attempts to engage the coronary sinus with a variety of guiding sheaths and guidewires. A non-selective venogram of the right atrium failed to reveal a coronary sinus ostium. Further attempts to engage the coronary sinus were abandoned and the patient underwent a cardiac CT scan with filling of contrast during the venous phase. This demonstrated drainage of the coronary sinus into the left atrium. The patient had no signs or symptoms of hypoxia or shunting. Conclusion: This is first reported case of inability to place a coronary sinus lead due to an anatomical variant involving drainage of the coronary sinus to the left atrium. This should be considered when confronted with a coronary sinus that cannot be cannulated. RECURRENT SYNCOPE ASSOCIATED WITH LQT3 AND ATRIOVENTRICULAR BLOCK Kit Chan, MBBS, FHRS, MY Liu, MD, PhD, CT Zhao, MD, PhD, Linda Lam, MD, FRCP, KH Yiu, MBBS, PhD and HF Tse, MBBS, PhD. The University of Hong Kong Shenzhen Hospital, Hong Kong, Hong Kong Background: Congenital long QT syndrome with atrioventricular block (AVB) is associated with syncope and sudden cardiac death. Objective: We describe a child with recurrent exertional syncope associated with LQT3 phenotype, coexisting 2:1 AVB and a novel SCN5A mutation. Methods: N/A Results: A 12-year-old girl was admitted for syncope after exercise. She experienced recurrent syncope after swimming and long jump over the past 1 year. She did not experience any preceding cardiac or neurological symptoms. Her medical history and family history were unremarkable. She was not taking any medication. Physical examination was unrevealing. Baseline ECG showed normal sinus rhythm. The QTc interval was 511ms, with late peaking of T waves. Twenty-four hour holter showed normal sinus rhythm with intermittent 2:1 AVB. The longest R-R interval was 1.61 seconds. The average heart rate (HR) was 66 beats per minute (bpm) (HR range: bpm). Blood tests and echocardiogram were unremarkable. Exercise stress test showed 1:1 AV conduction up to 116bpm, followed by intermittent 2:1 AVB at peak stress. The QTc was initially shorted from 500ms at baseline to 450ms at peak stress. However, it was lengthened to 516ms at 4 minutes in recovery stage. Patient was asymptomatic, but the stress test was prematurely terminated due to exercise induced AVB and non-sustained ventricular tachycardia. Genetic screening detected a novel mutation of SCN5A (NM_ ; c.5134 A >G). Her Schwartz score was 6, suggestive of high clinical probability of LQTS. Her ECG morphology was compatible with LQT3 phenotype. The patient and her family were offered the option of betablocker, mexiletine and close rhythm monitoring with implantable loop recorder. However, her family opted for implantable cardioverter defibrillator implantation in another hospital. She was treated with moricizine, which shortened her baseline QTc to 423ms. Conclusion: We presented a patient with congenital LQT3 phenotype, coexisting 2:1 AV block and a novel genetic mutation of SCN5A. Moricizine could be an useful therapeutic option in shortening QTc interval.

101 S588 Heart Rhythm, Vol. 15, No. 5, May Supplement 2018 B-PO CUSTOMIZED ECHOCARDIOGRAPHIC PACEMAKER OPTIMIZATION ACHIEVES BETTER HEMODYNAMICS THAN TRADITIONAL PACEMAKER ALGORITHMS Nityanand Peri, DO, Zaid Rana, DO and John R. Dylewski, MD, FHRS. Larkin Community Hospital, South Miami, FL, Arrhythmia Management Institute of South Florida, Coral Gables, FL Background: Two methods to program pacemakers are: 1) preset algorithms that mimic physiologic cardiac function, and 2) real-time echocardiography to modify atrioventricular (AV) delay and maximize diastolic function. As diastole comprises 2/3 of the cardiac cycle, optimizing it has physiologic and clinical benefits. Echo assesses E/A wave ratios (an index of diastolic function) and can be used to improve hemodynamics in patients who are not optimized with device algorithms. Objective: Demonstrating echo AV optimization is an option for patients who fail preset pacer algorithms. Methods: A case series Results: Case 1: A 65-year-old Hispanic male with severe HFrEF of 15% who remained symptomatic after dual chamber ICD placement. Baseline echo showed hypokinesis of the septal wall and dys-synchrony between the septal and posterior walls. Initial E/A ratio of mitral inflow showed a truncated A and partial fusion of the E/A. After programming an AV delay of 150msec, the E/A ratio was 1 with no truncation or fusion of the E and A waves. The patient s LV contractility and synchronicity of posterior and septal walls both improved, while right ventricular systolic pressure remained stable. Case 2: An 87-year-old African American female with history of atrial fibrillation, ventricular tachycardia, and cardiomyopathy with LVEF 35-40% with previous VV optimization in She presented with dizziness and lightheadedness requiring pacer battery change and VV optimization. During echo study, her pacer was modified to include an LV-RV delay of 80msec, a nonalgorithmic setting leading to improved septal and posterior wall synchronicity, especially in systole. Post-procedure LVEF was 45-50%. Conclusion: The cases demonstrate the benefit of echo optimization in cardiac device patients who fail traditional algorithms. By setting individual pacer settings to maximize AV and VV delay and improve diastolic function, both improvement in cardiac hemodynamics and patient quality of life are achieved. The patients reported subjective improvement in cardiac function, and we intend to follow these patients to assess longterm outcomes. B-PO INTRA-PULMONARY VEIN ECHO BEATS Sok-Sithikun Bun, MD, MBBS, Decebal Gabriel Latcu, MD, Ahmed Mostfa Wedn, MD and Nadir Saoudi, MD, FHRS. Princess Grace Hospital, Monaco, Monaco Background: We report a unique case of intra-pulmonary vein (PV) echo beats. Objective: To describe a rare observation of intra-pv echo beats recording. Methods: A 55-year-old female patient was referred for drugrefractory atrial fibrillation (AF) ablation. She underwent an ablation procedure under general anesthesia (point-by-point contact force-guided radiofrequency ablation). Results: After finishing the left PV encirclement, residual potentials were recorded on the duodecapolar circular mapping catheter (CMC) within the left superior PV during sinus rhythm. On figure A (from the top), two surface ECG leads (I and V1) are shown and the bipolar recordings on the CMC and of the proximal coronary sinus. PV automaticity was demonstrated (cycle length 2470 ms), but with a delayed second component suggesting echo beats within this PV. This second component had a fixed coupling interval with the first component (260 ms). Some entrainment manoeuvers were performed: pacing at a cycle length of 1880 ms on the bipole of the CMC could elicit capture of the first component with persistence of the second component (Figure B). PV automaticity was targeted until complete abolition of both intra-pv potentials. No dormant conduction was revealed by intravenous adenosine injection after PV automaticity elimination. After a follow-up of 24 months, the patient was free from any atrial arrhythmia without antiarrhythmic drug. Conclusion: This phenomenon may be related to a small reentry within the vein, with catheter-induced creation of a zone of slow conduction. To the best of our knowledge, PV echo beats (intra-pv reentry) have been reported and recorded only in PV rat myocardium. B-PO UNUSUAL ETIOLOGY OF ATRIAL STANDSTILL Praloy Chakraborty, MD, Hermohander Singh Isser, MD and Sudheer Kumar Arava, MD. VMMC and Safdarjang Hospital, New Delhi, India, AIIMS, New Delhi, India Background: Atrial standstill is characterised by the absence of atrial electrical and mechanical activity. There are three forms: idiopathic, inherited or secondary Objective: N/A Methods: N/A Results: : A 30 year old male presented with history of ischemic stroke. Surface ECG showed irregular ventricular rate and no visible P wave. Echocardiography showed dilatation of RA and RV. Tran-tricuspid pulse Doppler imaging (A) showing the absence of A waves. Invasive electrophysiological testing was suggestive of atrial standstill. A histological specimen from the right ventricular endocardium was normal. His mother had history of atrial and ventricular arrhythmias. His maternal aunt underwent permanent pacemaker implantation due to sick sinus syndrome. He was subjected to genetic analysis by Next Generation sequencing (NGS) technique, which showed that the individual harbours variation in SCN5A (p.asp1275asn) gene. Mutation analysis study showed that his mother and maternal aunt harbour the same variation in SCN5A.Case 2: A 34 year old male presented with exertional breathlessness. ECG showed slow junctional rhythm with incomplete right bundle branch block. Echocardiography showed dilated RA and RV along with absent trans-tricuspid A wave in pulse Doppler. Cardiac MRI showed dilated RA and RV with severe tricuspid regurgitation (TR).

102 S589 Poster Session V Invasive electrophysiological testing suggested no atrial activity with suprahisian escape rhythm. The atrium was inexcitable on stimulation. Endomyocardial biopsy from Right ventricular septum was normal. He was subjected to genetic analysis by Next Generation sequencing (NGS) technique, which showed that the individual harbours variation in TRPM4 (p.gln293arg) gene. His parents are not available for genetic analysis.apart from infiltrative disease like amyloidosis, permanent atrial standstill can rarely occurs due to Channelopathy like connexin 40 (Cx40) and SCN5A mutation.variations in the TRPM4 gene have been shown to be associated with progressive familial heart block. Conclusion: We report 2 rare cases of atrial standstill associated with cardiac channelopathy B-PO A KNOTTY CASE AND TECHNIQUE TO UNRAVEL IT Vern Hsen Tan, MBBS and Kelvin Wong. Cardiology Department, Changi General Hospital, Singapore, Singapore, Changi General Hospital, Singapore, Singapore Background: Catheter knotting is a known complication of intravascular procedure especially performed without fluoroscopy. Objective: We describe what we believe is the first case of knotting of a quadpolar diagnostic catheter during electrophysiology procedure without the use of fluoroscopy and technique to unravel it. Methods: N/A Results: 74-year-old man presented with symptomatic recurrent supraventricular tachycardia (adenosine sensitive) consented to undergo electrophysiology study and ablation. The procedure was initially conducted using three dimensions electroanatomic mapping without fluoroscopy. Three catheters were used for the electrophysiology study (decapolar catheter was placed at coronary sinus, quadpolar catheter was placed at His as well as right ventricular apex respectively) via right femoral vein using short sheaths. After completing electrophysiology study, quadpolar catheter from right ventricular apex was withdrawn in order to exchange with ablation catheter. However, it was difficult to withdraw the quadpolar catheter completely out of femoral sheath and hence, fluoroscopy was used. There was a knot formed along the proximal aspect of the catheter (therefore prevent removal of the catheter) on fluoroscopy. A long sheath (SRO) together with dilator was inserted together with guide wire. The guide wire was then maneuvered through the knot followed by the dilator and sheath while maintaining traction on the catheter (push and pull technique) in order to open up the knot. Next, with the existing long sheath inside the knot, another long sheath (SRO) was used to cross and open up the knot further. Next, one of the long sheaths was exchange with Agillis catheter to provide a good traction. While maintaining the traction on the Agillis catheter, the other long sheath was pushed against the knot (push and pull technique). Finally, the knot was unraveled. The ablation procedure was subsequently resumed. The patient finally underwent successful ablation of concealed right anterolateral accessory pathway. Conclusion: Catheter knotting is a potential complication when performed without fluoroscopy. Our case highlighted the first reported case of electrophysiology catheter knotting and technique to unravel it. B-PO TRANSVENOUS IMPLANTABLE CARDIOVERTERDEFIBRILLATOR WITH SHOCK LEAD FRACTURE SWITCHED TO SUBCUTANEOUS IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR AND AAI PACEMAKER Ruiko Seki, MD, Kanki Inoue, MD, Morimasa Takayama, MD, PhD, Jun Umemura, MD and Mitsuaki Isobe, MD. Sakakibara Heart Institute, Tokyo, Japan Background: There are great concerns about the risks associated with intravascular leads. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are expected to minimalize these problems. Objective: We present a demonstrable case of hypertrophic cardiomyopathy complicating an intravascular shock lead fracture treated with S-ICD and AAI pacemaker. Methods: N/A Results: A 76-year-old female with hypertrophic obstructive cardiomyopathy was prophylactically implanted with a transvenous ICD (TV-ICD) nine years ago because of the high risk of sudden cardiac death. To alleviate her severe heart failure symptoms, alcohol septal ablations were performed twice. The patient was admitted to our hospital for inaprropriate shock deliveries due to the shock lead fracture. She had sick sinus syndrome and first-degree atrioventricular block with full atrial pacing. The atrial lead was still available. There was almost no ventricular pacing. She had no experience with anti-tachycardia pacing therapy. A venography revealed her left subclavian vein was narrowed. Considering all the above findings, we decided to switch from a transvenous ICD to an AAI pacemaker and implant an S-ICD without extracting the intravascular shock lead. After the implantation of the S-ICD, the patient experienced no inappropriate shock therapy. Conclusion: In intravascular shock lead failure, changing from a TV-ICD to a S-ICD and an AAI pacemaker is a promising therapeutic option.