B-ab17-03 long-term half-dose novel oral anticoagulation versus standard antithrombotic therapy after left atrial appendage occlusion with a watchman device

No consensus currently exists on the selection of the most effective antithrombotic strategy to prevent device-related thrombosis (DRT) in patients undergoing left atrial appendage (LAA) occlusion. We evaluated the long-term efficacy of a standard antithrombotic strategy versus half-dose novel oral anticoagulation (NOAC) after Watchman implantation. Consecutive Watchman patients were prescribed a standard antithrombotic strategy (Group SAT) with clopidogrel for the first 6 months plus long-term aspirin or long-term NOAC monotherapy at half dose (Group hdNOAC). The primary composite endpoint was DRT, thromboembolic (TE), and bleeding events. 555 patients (mean age: 75±8 years, 63% males; CHA2DS2-VASc: 4.5±1.4; HAS-BLED: 3.2±1.0) were included. Patients were categorized into two groups (Group SAT: 357 patients vs Group hdNOAC: 198 patients). Baseline clinical characteristics were similar between groups. The mean follow-up duration was 14±5 months. DRT occurred in 12 (2.1%) patients, all in Group SAT (3.4% vs 0.0%; log-rank p-value: 0.009). The risk of nonprocedural major bleeding was significantly more favorable in the hdNOAC group (0.5% vs. 3.9%; log-rank p-value: 0.018). The rate of the primary composite endpoint of DRT, TE and major bleeding events was 9.5% in SAT patients and 1.0% in hdNOAC patients (hazard ratio: 9.8; 95% confidence interval: 2.3-40.7; p-value: 0.002). After successful Watchman implantation, long-term half-dose NOAC significantly reduced the risk of the composite endpoint of DRT, TE, and major bleeding events compared to a standard, antiplatelet-based, antithrombotic therapy.