Electrical cardioversion of atrial fibrillation.

External direct current cardioversion remains the most common and effective method for restoration of normal sinus rhythm in patients with persistent AF. The development of biphasic defibrillators allows for higher success rates of conversion using standard energy levels. For persistent AF, an initial energy of 200 J is recommended for biphasic defibrillators, and 300 to 360 J are recommended for monophasic defibrillators, with the electrodes placed in the anterior posterior position. For refractory cases, alternatives are available such as dual defibrillators or internal cardioversion. Antiarrhythmic drugs may enhance the results of cardioversion by helping overcome shock failure or by preventing immediate recurrence of AF. Thromboembolism is the most important complication associated with cardioversion, but it can be prevented by providing 3 weeks of anticoagulation before the procedure or by excluding the presence of thrombi by transesophageal echocardiography, followed by an additional 4 weeks of anticoagulation.