Clinical and electrophysiologic effects of amiodarone in patients with atrial fibrillation complicating the Wolff-Parkinson-White syndrome.

The clinical and electrophysiologic effects of oral amiodarone were evaluated in 10 patients with a history of spontaneous atrial fibrillation and a rapid ventricular response, complicating the Wolff-Parkinson-White syndrome. Five patients developed ventricular fibrillation during an episode of atrial fibrillation. Seven patients underwent electrophysiology study and arrhythmia induction, both before and during chronic amiodarone treatment. During a mean 30 months of follow-up (range 8 to 59 months), no recurrences of atrial fibrillation or ventricular fibrillation were noted. One patient had recurrent supraventricular tachycardia and underwent surgery. One had serious and five had minor side effects. Arrhythmia suppression was associated with prolongation of the anterograde accessory pathway (+38%, p less than 0.01) and atrial (+34%, p less than 0.01) effective refractory periods. Amiodarone also slowed the ventricular response to induced atrial fibrillation, prolonging the mean (+90%, p less than 0.01) and minimum (+104%, p = 0.01) R-R intervals. Thus, amiodarone is a safe and effective alternative for arrhythmia prevention if surgery is inadvisable or is not desired by the patient.