Current recommendations for the anticoagulation of patients with atrial fibrillation.

Atrial fibrillation (AF) is the most commonly encountered cardiac rhythm disorder and is strongly associated with stroke. The risk of stroke and the benefit of anticoagulant therapy in patients with AF associated with mitral stenosis has been well accepted. Until recently the risk of stroke and the role of anticoagulant therapy in patients with nonrheumatic AF was unclear. Over the past decade studies have shown an approximate fivefold increase in the risk of stroke in patients with nonrheumatic AF. The results of large clinical trials have shown a benefit of treatment with anticoagulants and, to a lesser extent, aspirin for both the primary and secondary prevention of thromboembolic complications. Other than patients with a low risk of thromboembolic complications (primarily young patients without clinical risk factors), current guidelines recommend anticoagulation of most patients with AF. The studies that form the basis for these recommendations and the currently published guidelines are reviewed.