Summary: Evaluated warfarin versus aspirin patients with atrial fibrillation for thromboembolism prophylaxis. Warfarin superior to aspirin in high risk patients to reduce primary endpoint of stroke and systemic embolism. Aspirin alone safe in lower risk patients (age < 75, no hypertension or prior embolism).

Original Publication:

Lancet. 1994 Mar 19;343(8899):687-91.

Eponym: Stroke Prevention in Atrial Fibrillation Study II