P4240Temporal occurrence of thromboembolic events with interruption of anticoagulation therapy following left atrial appendage isolation

Abstract

Background: Since being recognized as a source of arrhythmogenic triggers, electrical isolation of left atrial appendage (LAA) is performed as part of the ablative therapy in many patients with atrial fbrillation (AF). However, LAA is also known as the main nidus for thrombus formation in AF patients, necessitating life-long oral anticoagulation (OAC) following isolation of the appendage (LAAI) to reduce the risk of thromboembolic (TE) events. Objective: We evaluated the temporal association of the risk of stroke or transient ischemic attack (TIA) with discontinuation of OAC in the post-LAAI period. Methods: A total of 1854 consecutive AF patients receiving LAAI were included in the analysis. Patients remained on OAC (dose-adjusted warfarin or the new OACs [NOAC]) for 6 months post-procedure, when the follow-up TEE was performed to assess the LAA contractility and fow velocity Those with normal function were allowed to discontinue and patients with abnormal LAA function were asked to continue on OAC. Results: After the TEE evaluation at 6 months, 1086 patients with suboptimal LAA function remained on-OAC. At a median follow-up of 2.3 years (IQR 1.9-4.2 years), 18 TE events (1.66%) were reported; 5 TIAs and 13 strokes. These events occurred in patients with CHADS2-VASc score of 0-4. Six of the 18 patients were on warfarin and 12 on NOACs. All patients had the anticoagulant temporarily discontinued at the time of the event for either planned medical procedures or because of poor compliance The mean time from discontinuation of the OAC to the TE event was 3.38±2.62 days.However, 16 patients with abnormal LAA velocity did not experience any event despite being off-OAC during a follow-up period of 2-4 years. Conclusion: Uninterrupted anticoagulation is critical in the management of patients following LAA isolation, as stroke/TIA can happen as soon as a day after discontinuation the drug irrespective of the CHADS2-VASc scores. Further studies are warranted to understand the underlying mechanism of differential predisposition for TE events in off-OAC patients.