Antithrombotic therapy in atrial fibrillation.

Warfarin is highly effective at reducing the risk of stroke in atrial fibrillation. The benefit of oral anticoagulant therapy strongly outweighs the risk in most patients with atrial fibrillation. More data are needed to define better the overall risk-to-benefit ratio for patients age 80 years and greater. Because a significant proportion of elderly individuals may not be optimal candidates for anticoagulant therapy, alternative stroke prevention strategies must continue to be evaluated while redoubling efforts to understand the mechanisms underlying atrial fibrillation and thrombogenesis.