Comparing the guidelines: anticoagulation therapy to optimize stroke prevention in patients with atrial fibrillation.

Atrial fibrillation (AF) is an important risk factor for stroke. According to a pooled analysis of controlled clinical trials with warfarin, anticoagulation therapy reduces stroke risk by 62%. However, clinicians must decide whether the benefit of long-term anticoagulation therapy with available agents outweighs the risk of bleeding for individual patients. Guidelines issued by the American College of Chest Physicians and by the joint American College of Cardiology, American Heart Association, and the European Society of Cardiology task force recommend antithrombotic therapy to protect AF patients from stroke based on risk-stratification algorithms. Risk factors for stroke AF patients include age > or =75 years; hypertension; thyrotoxicosis; diabetes; cardiovascular disease; congestive heart failure; and history of stroke, transient ischemic attack, or thromboembolism. Patients at high risk for stroke experience greater absolute benefit from anticoagulation therapy than patients at low risk. The guidelines are consistent in recommendations for high-risk patients (warfarin therapy, international normalized ratio 2.0 to 3.0) and low-risk patients (aspirin 325 mg), but differ for intermediate-risk patients with diabetes or heart disease. The guidelines continue to evolve, and future guidelines are likely to incorporate new clinical data, including the CHADS(2) algorithm for determining risk and the results of the Atrial Fibrillation Follow-up Investigation of Rhythm Management trial, the Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation study, and the Stroke Prevention Using an Oral Thrombin Inhibitor in Atrial Fibrillation II to V trials.