Watching 'AF'ter the Heart: the WATCHMANTM device for atrial fibrillation.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a leading cause of cardioembolic stroke. In nonvalvular atrial fibrillation (NVAF), thrombus formation occurs predominantly within the left atrial appendage (LAA), making it a key therapeutic target. While oral anticoagulation remains standard for thromboembolic risk reduction, contraindications, elevated bleeding risk, and therapy intolerance drive the need for nonpharmacologic alternatives. This review examines the role of the WATCHMAN left atrial appendage occlusion (LAAO) device in NVAF-related stroke prevention, encompassing pathophysiologic rationale, device design, procedural technique, clinical evidence, post-implantation management, and outstanding evidence gaps. The PROTECT AF and PREVAIL trials established WATCHMAN-based LAAO as noninferior to warfarin for prevention of stroke, systemic embolism, and cardiovascular death, though early procedural complications underscored the importance of operator experience. Subsequent real-world registries confirmed safety and effectiveness in higher-risk, anticoagulation-ineligible populations. Newer-generation platforms including the WATCHMAN FLX and FLX Pro, demonstrate improved sealing performance and procedural safety, while contemporary randomized trials further define LAAO's role relative to DOAC therapy. WATCHMAN-based LAAO represents an important alternative for carefully selected patients, particularly those with high bleeding risk. Optimal patient selection, antithrombotic regimens, and long-term outcomes warrant continued investigation.