Anticoagulation for prevention of stroke.

One of the important recent advances in stroke prevention is the demonstration that warfarin can substantially reduce the risk for stroke in patients with atrial fibrillation (AF). On average, patients with AF have a stroke risk of 4.5% per year. Anticoagulation reduces this to around 1.5% per year, a 70% relative risk reduction. The presence of additional risk factors, such as a recent stroke or transient ischemic attack, hypertension (particularly systolic hypertension), congestive heart failure, or diabetes, greatly increases stroke risk. Patients with any of these risk factors have a stroke risk of 8% per year or more. In contrast, patients under age 75 with none of these risk factors have a low risk for stroke (around 1% per year) when treated with aspirin. This risk stratification may help in identifying which patients with AF benefit most from anticoagulation. Anticoagulation has also been shown to prevent stroke in patients with other cardioembolic sources, including acute anterior wall myocardial infarction (particularly with echocardiographic evidence of thrombus), prosthetic heart valves, and dilated cardiomyopathies.