Drug treatment of atrial fibrillation: what have we learned?

Pharmacologic treatment continues to be the mainstay of therapy in patients with atrial fibrillation (AF). Over the past few years, considerable progress has been made in establishing the role of antiarrhythmic drug therapy for restoration and subsequent maintenance of sinus rhythm as well as for the control of ventricular rate in permanent AF. For pharmacologic cardioversion, intravenous or oral administration of class IC drugs is associated with success rates of 60% to 80% depending mainly on the duration of the arrhythmia. In persistent AF of longer than 1 week's duration, electrical cardioversion is recommended because this method is more effective and safer than drug therapy. For maintenance of sinus rhythm following successful cardioversion, class I drugs continue to be used often. However, there is increasing awareness of their proarrhythmic risk, particularly in the case of quinidine. Sotalol, a class III agent with beta-receptor antagonism, is as effective as quinidine but better tolerated. In patients with so-called refractory AF, amiodarone has been proven to be effective in approximately 60% to 70% of treatment attempts. For control of ventricular rate, digoxin, beta-blockers, and calcium-channel antagonists are widely used. In these patients, chronic anticoagulation with warfarin aiming at international normalized ratios between 2.0 and 3.5 has been documented to significantly reduce thromboembolic risk.