Use of Multiple Antithrombotic Drugs in Atrial Fibrillation Increases Bleeding Risk

In patients with atrial fibrillation, adding multiple-drug therapy to prevent thromboembolism can greatly increase the risk for major bleeding, according to an Archives of Internal Medicine study.

Investigators used Danish national databases to follow bleeding outcomes in some 80,000 patients with a discharge diagnosis of first-time atrial fibrillation. All patients had at least one postdischarge prescription for warfarin, aspirin, or clopidogrel. After a follow-up averaging 3.3 years, the relative risks associated with various regimens for fatal and nonfatal bleeding, relative to warfarin monotherapy, were as follows:

• Aspirin, 0.96
• Clopidogrel, 1.45
• Clopidogrel + aspirin, 1.91
• Warfarin + aspirin, 1.75
• Warfarin + clopidogrel, 3.57
• Warfarin + clopidogrel + aspirin, 4.03

The authors conclude that "combination therapy should be carefully considered and should be given only for a short time when treatments are mandatory."

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