136-27: Incidence and Predictors of LA Thrombus prior to Catheter Ablation of Atrial Fibrillation: A Multicenter Study

Abstract

Background: Transesophageal echocardiography (TEE) is commonly used prior to catheter ablation of atrial fibrillation (AF) in order to exclude left atrial (LA) thrombus. In patients presenting in SR or with AF duration 48h, TEE is not required if the patient has been anticoagulated in the weeks prior to ablation according to AF Guidelines. However, this recommendation is only based on expert consensus. This study aimed to evaluate whether the CHA2DS2-VASc score, in addition to the CHADS2 score, is useful for risk stratification with regard to the presence or absence of LA thrombus in patients prior to catheter ablation of AF. Methods: This study included 3000 cases (mean age 59 ± 11 years; 23% female; 39% persistent AF) referred for catheter ablation of AF in six University hospitals. Patients were anticoagulated for at least four weeks prior to the procedure. TEE was performed in all cases within 48 hours prior to ablation. Results: Pre-procedural TEE revealed LA thrombus in 54 of 3000 cases (1.8%), all located in the LA appendage. Among these 54 patients, 21 had paroxysmal AF and were in SR at tie of TEE. LA thrombus was present in 0.1%, 2.2%, and 4.4% of patients with CHADS2 scores of 0, 1, and ≥ 2, and in 0.4%, 2.9%, 3.5%, and 4.6% of patients with CHA2DS2VASc scores of 0/1, 2, 3, and ≥4, respectively. (Both p < 0.001) In multivariate analysis, a higher CHADS2 score, a higher CHA2DS2VASc score, and female gender remained significant predictors of LA thrombus (both p < 0.001). The CHA2DS2VASc score could be used to further stratify the patients with CHADS2 scores of 0/1 into 2 groups with different event rates (2.5% vs. 0.4%; p < 0.001) at a CHA2DS2-VASc cutoff value ≥2. Conclusions: Despite oral anticoagulation treatment, there is a small but significant incidence of LA thrombus by TEE prior to AF ablation even in SR patients. The CHADS2 and CHA2DS2-VASc scores are useful predictors of the risk for pre-procedural LA thrombus in patients undergoing catheter ablation of AF. The CHADSVASc score may help to identify patients at risk for LA thrombus with low CHADS scores.