Oral Anticoagulants Versus Antiplatelet Therapy for Preventing Stroke in Patients With Nonvalvular Atrial Fibrillation and No History of Stroke or Transient Ischemic Attacks

N onvalvular atrial fibrillation (AF) is a common cardiac arrhythmia, affecting about 0.7% of the general population.1,2 Its prevalence increases with age; about 5% of people over age 65 years and 10% of people over the age of 80 years experience AF. 1 Nonvalvular AF carries an increased risk of stroke mediated by embolism of stasis-precipitated thrombi originating in the left atrial appendage.Both oral anticoagulants and antiplatelet agents have proven effective for stroke prevention in many patients at high risk for vascular events (ie, for secondary prevention), but primary stroke prevention in patients with nonvalvular AF potentially merits separate consideration because of the suspected cardioembolic mechanism of most strokes in AF patients.