Anemia is associated with bleeding and mortality, but not stroke, in patients with atrial fibrillation: Insights from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial

Background Patients with atrial fibrillation (AF) are prone to cardiovascular events and anticoagulation-related bleeding complications. We hypothesized that patients with anemia are at increased risk for these outcomes. Methods We performed a post hoc analysis of the ARISTOTLE trial, which included >18,000 patients with AF randomized to warfarin (target international normalized ratio, 2.0-3.0) or apixaban 5 mg twice daily. Multivariable Cox regression analysis was used to determine if anemia (defined as hemoglobin <13.0 in men and <12.0 g/dL in women) was associated with future stroke, major bleeding, or mortality. Results Anemia was present at baseline in 12.6% of the ARISTOTLE population. Patients with anemia were older, had higher mean CHADS ₂ and HAS-BLED scores, and were more likely to have experienced previous bleeding events. Anemia was associated with major bleeding (adjusted hazard ratio [HR], 1.92; 95% CI, 1.62-2.28; P <.0001) and all-cause mortality (adjusted HR, 1.68; 95% CI, 1.46-1.93; P <.0001) but not stroke or systemic embolism (adjusted HR, 0.92; 95% CI, 0.70-1.21). The benefits of apixaban compared with warfarin on the rates of stroke, mortality, and bleeding events were consistent in patients with and without anemia. Conclusions Chronic anemia is associated with a higher incidence of bleeding complications and mortality, but not of stroke, in anticoagulated patients with AF. Apixaban is an attractive anticoagulant for stroke prevention in patients with AF with or without anemia.