Warfarin and aspirin as thromboprophylaxis in atrial fibrillation.

1. Anticoagulant therapy with warfarin is now established as effective thromboprophylaxis against stroke in atrial fibrillation, in high-risk persons. Aspirin is indicated in moderate-risk persons or if warfarin is contraindicated. 2. Risk stratification is suggested, using clinical factors supplemented by echocardiography, to aid choice of prophylaxis. 3. Further studies are required to establish how best to identify undiagnosed patients who have atrial fibrillation; to develop new therapeutic strategies; and to refine risk stratification to define which patients with atrial fibrillation are at the highest risk of stroke.