Anticoagulation Therapy for Stroke Prevention in Atrial Fibrillation

Abstract

Multiple randomized trials have demonstrated warfarin therapy to be highly efficacious in reducing risk of ischemic stroke and other systemic thromboembolism in patients with atrial fibrillation, with relatively low rates of bleeding.^1-5 Aspirin has substantially less efficacy, particularly among patients at moderate to high risk of stroke.^2,3,6 However, concerns persist about the effectiveness and safety of anticoagulation with warfarin in persons treated in usual clinical care because the randomized trials enrolled highly selected patients, included few very elderly patients, and closely monitored anticoagulation. This has important clinical implications because atrial fibrillation occurs commonly, particularly among the elderly,⁷ and because the potential benefits vs risks of warfarin therapy are dependent on good control of anticoagulation intensity within a relatively narrow international normalized ratio (INR) range.^8-10