Role of transthoracic echocardiography in atrial fibrillation.

Atrial fibrillation is a major clinical problem that is predicted to be encountered more frequently as the population ages. The clinical management of atrial fibrillation has become increasingly complex as new therapies and strategies have become available for ventricular rate control, conversion to sinus rhythm, maintenance of sinus rhythm, and prevention of thromboembolism. Clinical and transthoracic echocardiographic features are important in determining etiology and directing therapy for atrial fibrillation. Left atrial size, left ventricular wall thickness, and left ventricular function have independent predictive value for determining the risk of developing atrial fibrillation. Left atrial size may have predictive value in determining the success of cardioversion and maintaining sinus rhythm in selected clinical settings but has less value in the most frequently encountered group, patients with nonvalvular atrial fibrillation, in whom the duration of atrial fibrillation is the most important feature. When selecting pharmacological agents to control ventricular rate, convert to sinus rhythm, and maintain normal sinus rhythm, transthoracic echocardiography (TTE) allows noninvasive evaluation of left ventricular function and hence guides management. The combination of clinical and transthoracic echocardiographic features also allows risk stratification for thromboembolism and hemorrhagic complications in atrial fibrillation. High-risk clinical features for thromboembolism supported by epidemiological observations, results of randomized clinical trials, and meta-analyses include rheumatic valvular heart disease, prior thromboembolism, congestive heart failure, hypertension, older (> 75 years old) women, and diabetes. Small series of cases also suggest those with hyperthyroidism and hypertrophic cardiomyopathy are at high risk. TTE plays a unique role in confirming or discovering high-risk features such as rheumatic valvular disease, hypertrophic cardiomyopathy, and decreased left ventricular function. Validation of the risk stratification scheme used in the Stroke Prevention in Atrial Fibrillation-III trial is welcomed by clinicians who are faced daily with balancing the benefit and risks of anticoagulation to prevent thromboembolism in patients with atrial fibrillation.