Atrial fibrillation: reducing stroke risk with low-dose anticoagulation.

Atrial fibrillation (AF) is the primary disorder predisposing patients to systemic embolism. Its incidence increases with age, rising from 2 to 4% of Americans aged 60 to 12% of women and 16% of men over age 75. AF is commonly associated with hypertension and coronary heart disease--particularly congestive heart failure. Five trials published since 1989 showed that giving oral anticoagulants to patients with AF can safely and effectively reduce the risk of embolic stroke. Long-term warfarin therapy is recommended by the American College of Chest Physicians for patients with AF who have associated cardiovascular disease, thyrotoxicosis, or are age 60 or older. The ACCP recommends an INR range of 2.0 to 3.0, which is as effective as high-intensity treatment but less likely to cause bleeding.