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Warfarin Better Than Aspirin plus Clopidogrel in Atrial Fibrillation

This large randomized trial was stopped early when a clear advantage was noted for warfarin in preventing stroke and non-CNS emboli.

Oral anticoagulants such as warfarin are far more effective than aspirin for preventing stroke in patients with atrial fibrillation, but such anticoagulants are difficult to manage and can cause major bleeding complications. Might clopidogrel plus aspirin offer a safer alternative to oral anticoagulation in patients with atrial fibrillation? In an international study, sponsored by manufacturers of clopidogrel and warfarin, researchers randomized more than 6700 patients with atrial fibrillation and at least one other stroke risk factor to receive either clopidogrel (75 mg once daily) plus aspirin (75–100 mg recommended) or oral anticoagulation with the locally preferred vitamin K antagonist (titrated to an INR between 2.0 and 3.0). About 12% of oral anticoagulation recipients also received aspirin during the trial.

When the study was stopped, after a median follow-up of 1.3 years, the primary composite outcome of stroke, non–central nervous system embolus, myocardial infarction, or vascular death had occurred at an annual rate of 5.6% in patients who received clopidogrel plus aspirin compared with 3.9% in patients who received oral anticoagulation — a highly significant difference. The individual endpoints of stroke and non-CNS embolus occurred significantly less often in patients who received oral anticoagulation than among those who received clopidogrel; differences in MI and vascular death were not significant. Rates of major hemorrhage were similar in the two groups, but significantly more minor bleeds and total bleeds were reported with clopidogrel plus aspirin than with oral anticoagulation.

Comment: Oral anticoagulation is more effective than combined antiplatelet agents for prevention of presumed embolic events in patients with atrial fibrillation.

— Bruce Soloway, MD

Published in Journal Watch General Medicine July 11, 2006

Citation(s):

The ACTIVE Writing Group on behalf of the ACTIVE Investigators. Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): A randomised controlled trial. Lancet 2006 Jun 10; 367:1903-12.

• Medline abstract (Free)

Verheugt FWA. Good old warfarin for stroke prevention in atrial fibrillation. Lancet 2006 Jun 10; 367:1877-8.

• Medline abstract (Free)