Oral anticoagulants versus antiplatelet therapy for preventing stroke in patients with non-valvular atrial fibrillation and no history of stroke or transient ischemic attacks.

Non-valvular atrial fibrillation (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 most patients at high risk for vascular events, but primary stroke prevention in patients with non-valvular AF potentially merits separate consideration because of the suspected cardio-embolic mechanism of most strokes in AF patients.