Ximelagatran Versus Warfarin: A Comparison of Bleeding Outcomes in Patients with Nonvalvular Atrial Fibrillation.

Background: The conventional anticoagulant management of patients with nonvalvular atrial fibrillation (AF) involves warfarin, administered to achieve a target international normalized ratio (INR) of 2.0–3.0. Ximelagatran is a novel oral direct thrombin inhibitor that, unlike warfarin, has a predictable anticoagulant effect and does not require dose adjustments based on the INR. In the SPORTIF III and V trials, ximelagatran was as effective as warfarin in preventing stroke and other thromboembolic complications in patients with nonvalvular AF. However, these studies were not designed to determine if ximelagatran was associated with a lower risk of major bleeding. Furthermore, these studies did not compare the case-fatality rate, time course, and anatomic sites of bleeding in ximelagatran- and warfarin-treated patients.

Methods: We undertook a pooled analysis of the SPORTIF III and V trials that involved 7329 patients with AF who received oral ximelagatran, 36 mg twice daily, or warfarin, administered to achieve a target INR of 2.0–3.0. Patients had nonvalvular AF and 1 or more risk factors for stroke: hypertension; age ≥75 yrs; previous stroke, transient ischemic attack or systemic embolism; left ventricular dysfunction; age ≥65 yrs and coronary artery disease; or age ≥65 yrs and diabetes. Major exclusion criteria were: mitral stenosis; previous heart valve surgery; transient AF; and increased risk for bleeding. Bleeding event rates were compared using Fisher’s exact test and the log-rank test and were expressed as the number of bleeds per year. The case-fatality rate of major bleeding was defined as the number of fatal bleeds divided by fatal plus nonfatal bleeds.

Results: The annual incidence of major bleeding was 2.0% in ximelagatran-treated patients and 2.7% in warfarin-treated patients (P = 0.029). The annual incidence of any (major or minor) bleeding was 31.7% in ximelagatran-treated patients and 38.8% in warfarin-treated patients (P < 0.0001). If episodes of intracranial hemorrhage were excluded, the annual incidence of major bleeding was 1.9% in ximelagatran-treated patients and 2.4% in warfarin-treated patients (P = 0.054). The case-fatality rate of major bleeding was 8.2% in ximelagatran-treated and 8.1% in warfarin-treated patients (P = 0.98). The time course and anatomic sites of major bleeding were not significantly different in ximelagatran-treated and warfarin-treated patients. Most bleeds involved the gastrointestinal tract, urinary tract or soft tissues.

Conclusion: In patients with nonvalvular AF who require long-term anticoagulation, treatment with oral ximelagatran, 36 mg twice daily, is associated with a lower risk of bleeding complications than warfarin.