Ximelagatran vs Warfarin for Stroke Prevention in Patients With Nonvalvular Atrial Fibrillation

To compare the efficacy of the oral direct thrombin inhibitor ximelagatran with warfarin for prevention of stroke and systemic embolism. DESIGN, SETTING, AND PARTICIPANTS: Double-blind, randomized, multicenter trial (2000-2001) conducted at 409 North American sites, involving 3922 patients with nonvalvular atrial fibrillation and additional stroke risk factors. INTERVENTIONS: Adjusted-dose warfarin (aiming for an international normalized ratio [INR] 2.0 to 3.0) or fixed-dose oral ximelagatran, 36 mg twice daily. MAIN OUTCOME MEASURES: The primary end point was all strokes (ischemic or hemorrhagic) and systemic embolic events. The primary analysis was based on demonstrating noninferiority within an absolute margin of 2.0% per year according to the intention-to-treat model.

During 6405 patient-years (mean 20 months) of follow-up, 88 patients experienced primary events. The mean (SD) INR with warfarin (2.4 [0.8]) was within target during 68% of the treatment period. The primary event rate with ximelagatran was 1.6% per year and with warfarin was 1.2% per year (absolute difference, 0.45% per year; 95% confidence interval, -0.13% to 1.03% per year; P