Atrial Pacing Lead with 1.1 mm Tip-to-Ring Spacing Clinical Data Summary: Avoid FFS Study A Multi-center, Randomized, Prospective Clinical Study Designed to Evaluate the 1699T Lead
Clinical Data Summary: AVOID FFS Study Introduction: Far-field sensing (FFS) is the most common cause of inappropriate mode switching episodes in dual-chamber pacing, yet FFS represents a stubborn problem for pacemaker clinicians to resolve effectively. FFS occurs when the atrial lead of a dual-chamber pacemaker detects signals from the ventricle and inappropriately senses them as intrinsic atrial events. The use of a new unique bipolar lead design that places the two distal electrodes in very close proximity to each other may mitigate this situation (see Figure 1). Figure 1 The bipolar atrial pacing lead is an active-fixation lead with a titanium-coated platinum-iridium helix (2 mm extension), tip size 7 mm 2, and tip-to-ring electrode spacing of 1.1 mm. The control lead (Tendril bipolar atrial lead) is comparable in specifications but uses a 10 mm tip-to-ring electrode spacing. Patients at the study centers indicated for an initial dualchamber pacemaker implant were randomized into one of two arms of the study ( lead group or conventional group) in a 1:1 pattern. PVAB was not optimized in the study group but programmed to the shortest possible value of 60 ms. In the control group, PVAB was optimized to a value at least 25 ms longer than the measured interval between QRS and sensed FFS at an atrial sensitivity of 0.1 mv. Atrial sensing threshold was programmed to 0.3 mv in both groups. Owing to the nature of this study, implanting physicians and following clinicians were not blinded. Large Spacing 10 mm Small Spacing 1.1 mm Larger antenna increases risk of far-field sensing. Short spacing reduces risk of far-field sensing. The AVOID FFS study is a randomized, multi-center prospective study with a sample size of over 180 patients, designed to investigate whether a new bipolar atrial lead with a very short tip-to-ring spacing shows equally low incidence of FFS with short PVAB (post-ventricular atrial blanking period) compared to optimized PVAB with standard bipolar atrial leads. A period of short-term follow-up yielded preliminary results regarding the sensing and pacing properties of two atrial pacing leads. Lead Overview: The AVOID FFS study evaluated the model 1699 atrial pacing lead with novel 1.1 mm tip-to-ring spacing of the lead s two distal electrodes. This unique electrode configuration is designed to offer more precise measurement and differentiation of atrial signals, considered to be clinically important features in terms of both avoiding far-field sensing and appropriately sensing low-amplitude atrial fibrillatory waves. This innovative lead design was compared in AVOID FFS to a conventional bipolar atrial pacing lead which relies on the established technology of 10 mm electrode spacing (the St. Jude Medical Tendril model 1388, 1688 or 1788 lead). Source: Lotze et al. Sensing and pacing properties of a new atrial lead with a 1.1 mm tip-to-ring spacing (AVOID FFS study). Study Objectives: The objective of the first interim analysis was to compare electrical performance of the two leads by measuring pacing threshold, sensing threshold, lead impedance, and contrasting atrial intracardiac electrograms (EGMs) post-discharge and at one month post-implant. The hypothesis of the study is that the use of a new lead with 1.1 mm tip-to-ring spacing and a short PVAB (programmed to 60 ms) is equally effective in suppressing FFS as a standard lead with additional FFS-test and PVAB optimization. Patient Demographics: A total of 204 patients participated in the study, all of whom had a conventional dual-chamber pacemaker indication. About 60% of patients were male. Mean ages of the patients at enrollment were 74±10 years for the control group (n=101) and 73±9 years for the study group (n=103), which is thought to be a representative age for the general pacemaker patient population (see Table 1). BASELINE CHARACTERISTICS of the PATIENT CONTROL GROUP STUDY GROUP P VALUE (n=101) (n=103) Mean age [±SD] (years) 74±10 73±9 0.58 Men (%) 60 (60) 61 (60) 0.97 Pacemaker indications 0.62 Sick sinus syndrome (%) 38 (37.6) 43 (41.7) AV block (%) 46 (12.5) 38 (36.9) Binodal disease (%) 15 (14.9) 20 (19.4) Other (%) 2 (2.0) 2 (1.9) Atrial lead placement 0.53 Lateral (%) 44 (43.6) 41 (39.8) Right atrial appendage (RAA) (%) 38 (37.6) 49 (47.6) Septal (%) 2 (2.0) 3 (2,9) Other (%) 17 (17.8) 10 (9.7) Fluoroscopy time [±SD] (s) 355±427 320±315 0.54 Procedure time [±SD] (min) 62±19 61±20 0.84 Clinical Data Summary: AVOID FFS Study Follow-up of 1 month (%) 95 (94.1) 99 (96.1) 0.50 Follow-up of 3 months (%) 94 (93.1) 94 (91.3) 0.23
Study Results: n Capture Thresholds: Atrial pacing thresholds were evaluated in both groups at discharge and again one month post-implant. Threshold measurements were performed at a pulse width of 0.4 ms and pulse amplitude thresholds (in voltage) were compared. leads had a lower but not significant (P=0.065) atrial pacing threshold at implant, but this lower threshold became significant (P=0.006) at one month post-implant (see Figure 2). This improvement is consistent with the electrical threshold performance observed with the initial FFS IDE clinical study performed in 2006. Figure 2 7 6 5 4 3 2 7 6 5 4 3 2 0.0 0. 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1. 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2. n Bipolar Atrial Sensing Thresholds: Atrial sensing thresholds did show a slight difference, with atrial bipolar leads having lower sensing thresholds at implant (P=0.006) and at one month post-implant (P<0.001) (see Figure 3); however, the ability of this lead to be programmed at more sensitive settings enables it to reliably sense the P waves. Figure 3 1 1 0.0 0.25 0.5 0.75 1,0 1.25 1,5 1.75 2.0 2.25 2.5 2.75 3.0 3.25 3.5 3.75 4.0 4.25 4.5 4.75 5.0 5.25 5.5 5.75 6.0 6.25 6.5 Minimal P Wave (mv) at discharge At discharge OptiSense P (n=92) (n=98) value P wave [mv] 2.57±1.30 2.0±1.19 0.006 Pacing Threshold (V @ 0.4 ms) at discharge At discharge OptiSense P P wave [mv] (n=90) (n=94) value Pacing threshold [V] 0.65±0.26 0.58±0.25 0.065 5 4 3 2 5 4 3 2-0.25 0.0 0.25 0.5 0.75 1.0 1.25 1.5 1.75 2.0 2.25 2.5 2.75 3.0 3.25 3.5 3.75 4.0 4.25 4.5 4.75 5.0 5.25 5.5 5.75 6.0 6.25 6.5 Minimal P Wave (mv) at 1 month post-implant At 1 month OptiSense P post-implant (n=88) (n=92) value 0.0 0. 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1. 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2. 2.2 P wave [mv] 2.69±1.30 2.05±1.12 <0.001 Pacing Threshold (V @ 0.4 ms) at 1 month post-implant At 1 month OptiSense P post-implant (n=81) (n=86) value Pacing threshold [V] 0.72±0.29 0.61±0.22 0.006
n Lead Pacing Impedance: Lead impedance, an indicator of how current travels through the lead, is a combination of the resistance within the lead itself and the impedance at the lead-tissue interface. leads showed higher impedance values at discharge (P<0.001) and one month post-implant (P=0.007) compared to conventional atrial bipolar leads (see Figure 4). The lead s higher impedance and equivalent or lower pacing thresholds compared with standard leads means less current drain which can positively impact device longevity. Figure 4 1 n Far-field Interference: Particularly meaningful for clinicians, intracardiac electrograms were obtained from both types of atrial bipolar pacing leads. Far-field sensing occurs because signals originating from the ventricle seem disproportionately large to the device s atrial sensing circuitry, creating a sort of electrical version of an optical illusion (see Figure 5). DeVoogt et al. reported that the ratio of intrinsic atrial signal amplitude to intrinsic ventricular signal amplitude for a conventional bipolar atrial pacing lead was approximately 5 to 1. 1 On the other hand, the P-to-R ratio for the pacing lead is approximately 40 to 1. Figure 5 1 200 250 300 350 400 450 500 550 600 650 700 750 Impedance at discharge At discharge OptiSense P (n=93) (n=99) value Impedance [ohms] 341±73 405±109 <0.001 1 1 Study Conclusions: The novel model 1699 atrial bipolar pacing lead with its unique 1.1 mm tip-to-ring electrode spacing was shown in the AVOID FFS randomized, controlled, prospective clinical trial to offer good and stable electrical performance characteristics compared to a conventional atrial bipolar lead with 10 mm tip-to-ring electrode spacing. In terms of atrial pacing thresholds, lead impedance, and sensing characteristics, this novel lead offered superior and often significantly superior performance characteristics. The authors conclude that initial results show great promise. Further recent study of this lead by de Groot et al. confirmed, FFRW can be suppressed without compromising P-wave sensing by using a pacing electrode with a short tip-ring distance. 2 1 De Voogt WG, Van Hemel NM, Willems AR, Visser J, Chitre Y, Bornzin G, Helland J. Far-field R-wave reduction with a novel lead design: Experimental and human results. PACE 2005; 28:782 788. 2 De Groot et al. Clinical results of far-field R-wave reduction with a short tip-ring electrode. PACE 2008; 31:1554 1559. 200 250 300 350 400 450 500 550 600 650 700 750 Impedance at 1 month post-implant At 1 month OptiSense P post-implant (n=88) (n+93) value Impedance [ohms] 333±67 361±67 0.007
St. Jude Medical is focused on reducing risk by continuously finding ways to put more control into the hands of those who save and enhance lives. AtriAl FibrillAtion CArdiAC rhythm MAnAgeMent CArdiAC Surgery CArdiology neuromodulation Cardiac Rhythm Management Division 15900 Valley View Court Sylmar, California 91342 usa +1 818 362 6822 +1 818 364 5814 Fax St. Jude Medical Sweden AB Veddestavägen 19 175 84 Järfälla Sweden +46 8 474 40 00 +46 8 760 95 42 Fax St. Jude Medical Coordination Center BVBA the Corporate Village da Vincilaan 11 box F1 1935 Zaventem belgium +32 2 774 68 11 +32 2 772 83 84 Fax Global Headquarters one lillehei Plaza St. Paul, Minnesota 55117 usa +1 651 483 2000 +1 651 490 4310 Fax sjm.com CAUTION: FEDERAL LAW (USA) RESTRICTS THIS DEVICE TO SALE, DISTRIBUTION AND USE BY OR ON THE ORDER OF A PHYSICIAN. Consult the User s Manual for information on indications, contraindications, warnings and precautions. Unless otherwise noted, or indicates that the name is a trademark of, or licensed to, St. Jude Medical, or one of its subsidiaries. ST. JUDE MEDICAL, the nine-squares symbol and MORE CONTROL. LESS RISK. are trademarks and service marks of St. Jude Medical, Inc. and its related companies. 2009 St. Jude Medical. All Rights Reserved. Item No. P0135