Anticoagulation in women with nonvalvular atrial fibrillation: insights from clinical trials.

There is emerging evidence that women with atrial fibrillation, particularly those aged over 75 years, are more prone to strokes than men. It is also generally believed that older women are more vulnerable than men to warfarin-associated hemorrhage, leading to reluctance among physicians to anticoagulate women with atrial fibrillation. In the SPORTIF trials, the largest randomized cohort of women with atrial fibrillation on anticoagulation, including those aged over 75 years, women developed stroke (either ischemic or hemorrhagic) and systemic embolic events more often than men. In population-based studies such as the ATRIA study, female gender increased the relative risk of stroke significantly (incremental relative risk: 20-90%). Both types of studies demonstrated that maintaining the international normalized ratio within the therapeutic range of 2.0-3.0 was associated with similar rates of major bleeding in older women, younger women and men. Better validated predictors of bleeding than gender should be considered when selecting antithrombotic therapy. New oral anticoagulants are under development to reduce the burden and risk of warfarin-associated anticoagulation.