Dual-Source cardiac computed tomography for the detection of left atrial appendage thrombus prior to ablation of atrial fibrillation: Single-center experience and analysis of literature C. Jilek, S. Fichtner, H. L. Estner, T. Reents, S. Ammar, J. Wu, T. Meyer, E. Hendrich, C. Kolb, J. Hausleiter, G. Hessling, I. Deisenhofer German Heart Center Munich, Technical University Munich, Germany
Disclosure Statement of Financial Interest I, Clemens Jilek, DO NOT have a financial interest / arrangement or affiliation with one or more organizations that could be perceived as a real or apparent conflict of interest in the context of the subject of this presentation. Cardiostim 2010 2
Background Catheter ablation has proven as standard procedure for symptomatic patients with drugrefractory atrial fibrillation (AF). Pre-procedural transesophageal echocardiography (TEE) is routinely used to detect thrombus in the left atrial appendage (LAA). Results from former published series suggest that cardiac computed tomography (cct) can be used for the same purpose with a high specificity between 85-94% but a low positive predictive value between 23-31%. Martinez et al. JACC Cardiovasc Imaging 2009; Kim YY, et al. Am Heart J 2007; Tang RB, et al. J Interv Card Electrophysiol 2008; 22(3):199-203. The main limitation of the published series are (1) a small sample size or (2) a CT-protocol not individualized to the patient. Analysis of negative predictive value and specificity of cct in detecting LAA thrombus prior to AF ablation with a specific CT-protocol individualized to the patient as compared to the gold standard TEE in a large single centre cohort. 3
Methods Consecutive examination of all patients presenting for ablation of AF between October 2006 and July 2009 who underwent TEE and cct within 48 hours. All patients were pre-treated with oral anticoagulation 4 weeks prior to ablation with an INR between 2 and 3. 64-slice, dual source cct scanner (Siemens Medical Solutions, Forchheim, Germany) with a protocol optimized for imaging pulmonary veins and individualized to the patient s rhythm: ECG gated cct-protocol for patients with sinus rhythm Non-ECG gated cct protocol for patients with AF or frequent APC/VPC The timing of cct scan was determined by contrast agent bolus tracking. TEE was used as gold standard. Negative predictive value, sensitivity and specificity were calculated for detecting thrombus in the LAA by cct. 4
Results LAA without thrombus LAA not fully contrasted Trabecularized LAA LAA with thrombus 5
Patients Characteristics All ECG triggered non-ecg triggered n=567 n=265 n=301 Age (yrs) 61±9.7 61±9.2 60±10.2 Gender male 397 (70%) 179 (68%) 212 (70%) BMI (kg/m 2 ) 26.5±6.4 25.8±6.34* 27.2±6.36* Rhythm (n=463) Sinus rhythm 240 (52%) 204 (77%) 36 (18%) SVES - 220 (48%) 191 (72%) 31 (16%) SVES + 8 (2%) 7 (3%) 1 (<1%) SVES ++ 12 (2%) 6 (2%) 6 (3%) Afib 223 (48%) 61 (23%) 162 (81%) Aflutter 2 (<1%) 0 (0%) 2 (1%) *p=0.024 6
Accuracy matrix for detecting LAA-thrombus by cct and TEE The prevalence of LAA-thrombus was 0.5% (3/567). Σ 567* CT + CT - TEE + TEE - 3 58 0.5% 10.2% 0 504 88.4% *2 LAA (0.4%) were not judgeable in the TEE, in the CT a thrombus could be ruled out. NPV 100 (CI 99-100) PPV 4.9 (CI 1-13) Specificity 90 (CI 86-92) Sensitivity 100 (CI 29-100) 7
Accuracy matrix for ECG-gated and non-gated cct ECG-gated Σ 265* TEE + TEE - Non-gated Σ 301 TEE + TEE - CT + 1 CT - 0 0.4% 23 239 90.2% *2 LAA (0.9%) were not judgeable in the TEE, in the CT a thrombus could be ruled out. CT + CT - 2 35 8.7% 0.7% 11.6% 0 264 0.0% 87.7% Specificity 91.2 (CI 87-94) NPV 100 (CI 98-100) Specificity 88.3 (CI 84-91) NPW 100 (CI 98-100)
Accuracy matrix analysis of literature Martinez et al. 2009, Tang et al. 2008 All pubmed-listed studies were included that compared imaging of LAA by TEE and by cct. Studies were excluded that included patients with spontaneous echocardiographic contrast. Σ 1137 CT + CT - TEE + TEE - 16 99 1.4% 8.7% 7 1015 0.6% 89.3% NPV 99.3 (CI 98-99) PPV 13.9 (CI 8-21) Specificity 69.6 (CI 47-86) Sensitivity 91.1 (CI 89-92) 9
Discussion Limitations This largest single-center study outlines the accuracy of the dual-source cct technology in detecting LAA-thrombi prior to left atrial ablation procedures. The low prevalence of LAA thrombi was a limitation in this study. The cct-protocol (ECG gated or non-gated) of our study was adapted to the predominant heart rhythm whereas former studies used exclusively one type of protocol irrespective of the heart rhythm. The false negative cct in the metanalysis were all performed with an old non-dualsource CT-generation. Specificity may be improved by optimized timing of contrast agent to improve filling of the LAA. 10
Conclusions The prevalence of thrombi in the LAA in anticoagulated patients prior to AF ablation is low. The negative predictive value of a routine dualsource cct not optimized for imaging of LAA in detecting LAA thrombi is high with a narrow confidence interval. 11
Thank you for your pleased attention 12