PROTECT AF was a multicenter, 2:1-randomized controlled trial that enrolled 707 subjects with non-valvular atrial fibrillation and a CHADS2 score ≥1 at 59 hospitals. The study compared left atrial appendage occlusion (LAAO) with the Watchman device (Boston Scientific, Marlborough, MA) to warfarin over a mean follow-up of 3.8 years. Patients treated with Watchman also received aspirin and warfarin until 45 days post-implant followed by aspirin and clopidogrel until 6 months post-implant. The trial found that the incidence of stroke, systemic embolism, and cardiovascular death was non-inferior with Watchman (8.4%) as compared to warfarin (13.9%).