Propensity-Matched Comparison of Oral Anticoagulation Versus Antiplatelet Therapy After Left Atrial Appendage Closure With WATCHMAN

Abstract

Objectives: In this propensity-matched analysis of post-left atrial appendage closure antithrombotic therapy, the safety and effectiveness of oral anticoagulation (OAC) and antiplatelet therapy (APT) were compared.

Background: Left atrial appendage closure with the WATCHMAN device is an alternative to OAC in patients with nonvalvular atrial fibrillation, who are at high bleeding risk. Initial trials included 45 days of post-implantation OAC, but registry data suggest that APT may suffice.

Methods: Patients from the PROTECT-AF (Watchman Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation), PREVAIL (Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy), CAP (Continued Access to PROTECT-AF), CAP2 (Continued Access to PREVAIL), ASAP (ASA Plavix Feasibility Study With Watchman Left Atrial Appendage Closure Technology), and EWOLUTION (Registry on WATCHMAN Outcomes in Real-Life Utilization) trials receiving either OAC or APT post-implantation were matched and compared for nonprocedural bleeding and stroke or systemic thromboembolism over 6 months following implantation. Each patient on APT was matched with 2 patients on OAC, with propensity scores derived from age, sex, congestive heart failure, hypertension, diabetes, prior transient ischemic attack or stroke, peripheral vascular disease, left ventricular ejection fraction, renal impairment, and different atrial fibrillation subtypes.

Results: The cohort on OAC (n = 1,018; 95% receiving warfarin and 5% receiving nonwarfarin OAC) was prescribed 45-day OAC post-implantation (92% also received single APT), followed by 6-month single or dual APT. The cohort on APT (n = 509; 91% receiving dual APT and 9% receiving single APT) received APT for variable durations. Six-month freedom from nonprocedural major bleeding was similar (OAC, 95.7%; APT, 95.5%; p = 0.775) despite more early bleeds with OAC. Freedom from thromboembolism beyond 7 days was similar between groups (OAC, 98.8%; APT, 99.4%; p = 0.089). However, device-related thrombosis was more frequent with APT (OAC, 1.4%; APT, 3.1%; p = 0.018).

Conclusions: After left atrial appendage closure with the WATCHMAN, although device-related thrombosis was more common with APT, both APT and OAC strategies resulted in similar safety and efficacy endpoints.

Keywords: antiplatelet therapy; antithrombotic therapy; atrial fibrillation; direct oral anticoagulation; left atrial appendage closure; oral anticoagulation; stroke.