Anticoagulation for atrial fibrillation in the elderly.

Atrial fibrillation is a risk factor for stroke, particularly among elderly patients. Multiple trials have established that antithrombotic therapy decreases stroke risk. Aspirin is associated with a relative risk reduction of about 21% and adjusted-dose warfarin (international normalized ratio 2.0-3.0) is associated with a relative risk reduction of about 68%. Warfarin is more effective than aspirin but is used less often than indicated because of hemorrhagic risk and the inconvenience of coagulation monitoring. The oral direct thrombin ximelagatran has been investigated for stroke prevention in patients with atrial fibrillation in two large clinical trials. The results suggest efficacy in a fixed dose compared with well controlled warfarin. Although anticoagulation intensity was not monitored or regulated during treatment with ximelagatran, it was associated with less bleeding than warfarin. Other antithrombotic agents are under development as alternatives to warfarin, but sufficient data are not yet available to justify their clinical use in patients with atrial fibrillation.