Maintenance of sinus rhythm after atrial defibrillation.

The long-term results of 356 episodes of atrial defibrillation by DC shock carried out in 250 patients are reviewed. In 78 per cent of the cases, atrial fibrillation recurred by the end of 12 months in spite of the administration of quinidine or procainamide or propranolol, singly or combined. However, when no antidysrhythmic drugs were used the recurrence rate was higher at all periods of observation and 100 per cent at the end of 12 months. The difference in the overall results between the untreated group and the treated groups with the exception of the propranolol group is significant (p less than 0.05). In addition, the propranolol group showed an obviously reduced recurrence rate at 1 month, but afterwards the results tended to approximate those in the untreated group. The period during which sinus rhythm could be maintained in patients who underwent valve operations was on the whole the same as in patients who did not have heart surgery. However, in a small number of patients sinus rhythm was maintained for longer periods after mitral valve replacement than before it. Sinus rhythm was maintained for significantly longer periods when atrial fibrillation lasted less than 1 year than when it had been present for more than 1 year (p less than 0.001). It is concluded that there is justification for a judicious antidysrhythmic prophylaxis after atrial defibrillation.