Atrial fibrillation

In 2000, some 2.3 million Americans were affected by atrial fibrillation, and that number is expected to rise as our population ages. Atrial fibrillation is both a reflection of active physiologic stressors on the body and a marker of future cardiac disease progression. The disorganized atrial activity that characterizes atrial fibrillation affects cardiac function, metabolic demand, and quality of life. However, our understanding of the etiology and treatment of this condition continues to advance with the result of recent large-scale clinical trials. Diabetes, hypertension, congestive heart failure, valvular disease, and myocardial infarction are all risk factors in the development of atrial fibrillation. And the diagnosis confers a five-fold increase in the incidence of stroke. (Patients at increased risk for stroke include those with congestive heart failure, hypertension, age greater than 75, diabetes, and previous stroke.) Anticoagulation is a critical action in most cases of atrial fibrillation, as data show a 68% relative risk reduction of stroke when patients are treated with warfarin. Prior to recent trials, achieving sinus rhythm was thought to invariably improve symptoms, cardiac function, and mortality. The adverse effects of antiarrhythmic medications are now being recognized, and treatment strategies emphasizing ventricular rate control have been recommended in recent clinical practice guidelines. This shift in thinking is influencing both outpatient and emergency department management. Controlling the ventricular rate in atrial fibrillation increases cardiac output, decreases the metabolic demand of the heart, and avoids the potentially dangerous side effects of rhythm-control drugs. Rate-control agents should be selected based on the clinical profile of individual patients. A well-chosen subset of patients may benefit from either chemical or electrical cardioversion; this appears to be a reasonably safe procedure and can be accomplished on an outpatient basis. Understanding causal etiologies, managing risk for stroke (and need for anticoagulation), addressing rate, and assessing the risks of cardioversion are key elements in a comprehensive approach to atrial fibrillation.