Left Atrial Appendage Occlusion vs. Oral Anticoagulants: Current Evidence and Debates

Atrial fibrillation (AF) is a major cause of cardioembolic stroke, and oral anticoagulation (OAC) remains the standard of care for thromboembolic prophylaxis. Because the left atrial appendage (LAA) is the dominant source of thrombus in AF, percutaneous LAA occlusion (LAAO) has been developed as a mechanical alternative for patients in whom long-term anticoagulation is problematic. Randomized trials against warfarin established non-inferiority for the composite endpoint, though not consistently across coprimary endpoints, and more recent trials against direct oral anticoagulants (DOACs) have extended this comparison to post-ablation and lower-risk populations. Across these studies a consistent pattern emerges: the clinical advantage of LAAO derives largely from a reduction in non-procedural bleeding rather than from superior ischemic protection, and recent meta-analyses diverge mainly according to how the thromboembolic endpoint is composed. At the extreme of stroke and bleeding risk, LAAO failed to demonstrate non-inferiority to physician-directed medical care. This review synthesizes the randomized evidence, examines methodological differences in endpoint construction and patient selection that complicate cross-trial comparison, and discusses determinants of procedural success including peridevice leak, device endothelialization, and device-related thrombus. Remaining evidence gaps are outlined, particularly for patients who experience ischemic stroke despite adequate anticoagulation.