Atrial fibrillation is a common condition, affecting over 1% of the population. Patients with atrial fibrillation have a five times higher stroke risk than those without the abnormality. Treatments that prevent blood from clotting (anticoagulants), such as warfarin, reduce stroke by a third compared to no treatment. Anticoagulants are the current gold-standard treatment to prevent stroke in patients with atrial fibrillation. However, treatment must be monitored and side effects include severe bleeding.

In the ACTIVE W trial, Stuart Connolly (McMaster University, Hamilton, Ontario, Canada) and colleagues assessed whether the combination of aspirin and clopidogrel, was a safe and effective alternative to anticoagulants. The investigators randomly assigned 6707 patients with atrial fibrillation to receive either an anticoagulant or a combination of aspirin and clopidogrel. The trial was stopped early after 2 years due to clear evidence for the superiority of anticoagulants over aspirin plus clopidogrel. The researchers found the risk of stroke was 3.9% per year (165 strokes) for those on warfarin and 5.6% per year (234 strokes) for those on the combined treatment.

See also accompanying Comment.

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Contact: Joe Santangelo
j.santangelo@elsevier.com
212-633-3810
Lancet
8-Jun-2006