Abstract

This article will review 2 clinical trials that recently compared the safety and efficacy of the oral direct thrombin inhibitor ximelagatran (fixed dose, 36 mg twice daily) with warfarin (adjusted dose, target international normalized ratio [INR] 2.0-3.0) in patients with nonvalvular atrial fibrillation and at least 1 risk factor for stroke. These noninferiority trials involved 7329 patients and a mean exposure to study drug of 18.5 months. The Stroke Prevention Using Oral Thrombin Inhibitor in Atrial Fibrillation (SPORTIF) III (open-label, N = 3407) and V trials (double-blind, N = 3922) were designed for pooled analysis, and the data showed the efficacy of ximelagatran therapy was comparable (noninferior) with extremely well-controlled warfarin therapy in preventing stroke and systemic embolic events; the primary event rates were 1.65% per year and 1.62% per year in the warfarin and ximelagatran groups, respectively (P = .941). In patients with a history of stroke or transient ischemic attack (about 20% of the SPORTIF population), the event rates were 3.27% per year and 2.83% per year in the warfarin and ximelagatran groups, respectively (P = .625). The distribution of stroke subtypes was similar in the 2 treatment groups. Intracranial hemorrhage occurred at a rate of 0.20% per year with warfarin and 0.11% per year with ximelagatran. Combined rates of minor and major bleeding were significantly lower with ximelagatran than with warfarin (32% per year vs 39% per year; P < .0001). The myocardial infarction rates were the same in the pooled database (no difference between agents). The aspirin data will be the subject of two substudy papers. Oral ximelagatran administered without coagulation monitoring or dose adjustment was as effective as well-controlled, adjusted-dose warfarin for prevention of stroke and systemic embolic events and was associated with significantly less total bleeding. This oral direct thrombin inhibitor is a potentially promising treatment option for the prevention of thromboembolism.