Cochrane Summaries

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Oral anticoagulants versus antiplatelet therapy for preventing stroke in patients with non-valvular atrial fibrillation and no history of stroke or transient ischemic attacks

Aguilar MI, Hart R, Pearce LA
Published Online: 
13 April 2011

Atrial fibrillation (AF) is an irregularity of the heartbeat that leads to blood clots forming in the upper chambers of the heart (the atria). These clots can break free and travel through the bloodstream to the brain and cause a stroke. Drugs that slow clotting, such as oral anticoagulants (warfarin and other coumarin derivates) and antiplatelet agents (aspirin and others), reduce the risk of stroke in patients with atrial fibrillation. In this review of eight randomized trials, including 9598 patients, oral anticoagulants are shown to reduce the risk of stroke in patients with non-valvular AF and with no prior stroke or transient ischemic attack by one-third when compared with antiplatelet agents alone. Antiplatelet agents reduce stroke by about 20% in AF patients compared with no therapy, offering a less efficacious therapeutic option for those deemed not eligible for anticoagulation therapy. The threshold of absolute benefit that warrants anticoagulation remains controversial and depends on patient's preferences and availability of optimal anticoagulation monitoring.