No abstract

Background: Ximelagatran is a novel oral direct thrombin inhibitor that is as effective as warfarin in preventing stroke and other thromboembolic complications in patients with nonvalvular atrial fibrillation (AF). Risk factors for bleeding with warfarin are known, but risk factors for bleeding with ximelagatran have not been described. Unlike warfarin, ximelagatran has a predictable anticoagulant effect, does not require anticoagulation monitoring, has a low potential for interactions with drugs, food, or alcohol, and is not affected by genetic polymorphisms. We undertook an exploratory analysis of a large patient database to identify conventional and novel risk factors for bleeding in ximelagatran-treated patients, in warfarin-treated patients, and in all patients, irrespective of treatment. Methods: We undertook a pooled analysis of the SPORTIF III and V trials trials, which included 7329 patients with nonvalvular AF who received oral ximelagatran, 36 mg twice daily, or warfarin, administered to achieve a target international normalized ratio of 2.0–3.0. Patients had nonvalvular AF and 1 or more risk factors for stroke: hypertension; age ≥75 years; previous stroke, transient ischemic attack (TIA) or systemic embolism; left ventricular dysfunction; age ≥65 years and coronary artery disease; or age ≥65 years and diabetes mellitus. Major exclusion criteria were: mitral stenosis; previous heart valve surgery; transient AF; increased risk for bleeding. Multivariate logistic regression analysis was used to identify independent risk factors for major bleeding. The hazard ratio (HR) for major bleeding, and corresponding 95% confidence interval (CI), was calculated for each variable in the regression model. Results: The Table presents risk factors in which there was a significant or a non-significant (NS) association with major bleeding in ximelagatran-treated or warfarin-treated patients, and in the combined patient population. Risk factor Ximelagatran-treated patients, HR (95% CI) Warfarin-treated patients, HR (95% CI) Combined patient population, HR (95% CI) Aspirin use 1.65 (1.07, 2.55) 2.40 (1.69, 3.42) 1.96 (1.49, 2.58) Increasing age 1.03 (1.01, 1.05) 1.06 (1.03, 1.08) 1.04 (1.03, 1.06) Prior liver disease NS 4.96 (1.57, 15.62) NS Prior stroke or TIA 1.78 (1.16, 2.73) NS NS Diabetes mellitus 1.80 (1.18, 2.75) NS 1.39 (1.05, 1.86) Asian race NS NS 1.99 (1.16, 3.42) Statin use 0.62 (0.39, 0.97) 0.61 (0.42, 0.88) 0.62 (0.39, 0.97) Conclusions: Overall, the bleeding risk was lower with ximelagatran compared with warfarin. Aspirin use and increasing age were associated with an increased risk of bleeding in both ximelagatran- and warfarin-treated patients. Statin use was associated with a decreased risk for bleeding in both groups.

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.