The majority of patients with nonvalvular atrial fibrillation (AF) have an indication for anti-coagulation to reduce the risk of stroke. As the left atrial appendage (LAA) is thought to the be the predominant source of thromboembolic events in the setting of AF, LAA closure may provide an alternative to anti-coagulation for stroke risk reduction without the associated bleeding concerns of anti-coagulation. This multi-center, randomized, unblinded trial compared LAA closure to warfarin in patients with AF and at least one other stroke risk factor (i.e. CHADS2 scores \u2265 1).\u00a0\u00a0 Patients were followed for four years and the primary outcome was a composite of stroke, systemic embolism, and cardiovascular\/unexplained death. In the intention to treat analysis for efficacy the LAA closure groups had 2.3 events per 100 patient-years compared to 3.8 events per 100 patient-years in the warfarin group (relative risk 0.60 favoring device; 95% credible interval, 0.41-1.05). The most frequent adverse event with the device was serious pericardial effusion and survival curves demonstrated an earlier risk of adverse events in the device group.<\/p>\n