The Amulet IDE Trial is an ongoing, prospective, randomized, multi-national trial, designed to evaluate the safety and effectiveness of the AMPLATZER Amulet Left Atrial Appendage Occluder for stroke prevention in comparison to the WATCHMAN Left Atrial Appendage Closure Device in patients with non-valvular atrial fibrillation. METHODS: Non-valvular atrial fibrillation patients at high risk of stroke (CHADS2 score ≥2 or a CHA2DS2-VASc score of ≥3) who are suitable candidates for left atrial appendage occlusion (LAAO) will be fully informed and requested to participate in the trial. A total of 1878 patients at up to 150 sites worldwide will be randomized in a 1:1 ratio between the AMPLATZER Amulet device (investigational) and the Boston Scientific WATCHMAN device (control). Each patient will be followed for 5 years, with follow-up assessments at discharge, 45 days, 3, 6, 9, 12, 18, and 24 months and then annually. The trial has three primary endpoints: A composite of procedure-related complications, or all-cause death, or major bleeding through 12 months (safety); a composite of ischemic stroke or systemic embolism through 18 months (effectiveness); and effective device LAAO, defined as residual jet around the device ≤5 mm at the 45-day visit (mechanism of action). SUMMARY: The Amulet IDE Trial is the first randomized head-to-head LAAO device trial and will provide data for the AMPLATZER Amulet occluder in a population with a high risk of stroke and bleeding.