Warfarin therapy is more effective than clopidogrel plus low-dose aspirin in preventing vascular events in patients with atrial fibrillation (AF) and 1 or more risk factors for stroke. The Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE-W) study enrolled more than 6700 patients. The investigators compared warfarin (international normalized ratio target 2-3) versus clopidogrel 75 mg daily combined with aspirin 75 to 100 mg daily for the prevention of first occurrence of stroke, non-central nervous system systemic embolism, myocardial infarction, or vascular death.Warfarin therapy was associated with a 44% relative risk reduction in these events.

Patients who were already receiving warfarin treatment at study entry had a trend toward a greater reduction in vascular events and a significantly lower risk of major bleeding events with oral anticoagulation than patients who were not on this therapy at study entry. The study was discontinued early because of the clear superiority of warfarin therapy.

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.