Disopyramide in patients with the Wolff-Parkinson-White syndrome and atrial fibrillation.

The effect of administration of disopyramide on the ventricular response to atrial fibrillation was studied in six patients with the Wolff-Parkinson-White syndrome. The drug was given intravenously to five patients during intracardiac electrophysiologic studies and to a sixth patient during electrocardiographic monitoring in a coronary care unit. One patient with a very rapid ventricular response to atrial fibrillation underwent a second electrophysiologic study after oral treatment for four weeks with disopyramide. In all cases, administration of disopyramide reduced the mean ventricular rate and increased the shortest interval between consecutive preexcited ventricular complexes during atrial fibrillation. Therapy with disopyramide should therefore be useful in preventing ventricular fibrillation which can result from a rapid ventricular response to atrial fibrillation in patients with an accessory atrioventricular pathway. There has been no recurrence of paroxysmal tachycardia in the four patients who have been maintained on oral therapy with disopyramide.