EFFECTS OF ORAL PROPAFENONE ADMINISTRATION BEFORE ELECTRICAL CARDIOVERSION OF CHRONIC ATRIAL-FIBRILLATION - A PLACEBO-CONTROLLED STUDY

Objectives. Our aim was to evaluate the benefits and risks of administ ering propafenone before electrical defibrillation for chronic atrial fibrillation. Background. In this context, an antiarrhythmic drug-alth ough potentially useful in preventing early recurrence of arrhythmia-c ould adversely affect the defibrillation threshold and reduce the card ioversion success rate. Methods. We randomly assigned 100 patients wit h chronic atrial fibrillation to oral treatment with either placebo (5 1 patients) or 750 mg/day of propafenone (49 patients) for 45 h before administration of direct current shock After successful cardioversion , all patients received propafenone therapy and were followed up for 4 8 h. Results. Before defibrillation, three patients in the propafenone group (6.1%) had reversion to sinus rhythm and one had sustained vent ricular tachycardia. Shock efficacy (82.4% vs. 84.4%) and the cumulati ve effective energy (395 +/- 258 vs. 421 +/- 236 J) were not different between the placebo and propafenone groups. In the propafenone group, 11 patients had their arrhythmia transformed into atrial flutter and required a lower energy level for arrhythmia conversion than did the o ther patients with continued atrial fibrillation (245 +/- 197 vs. 493 +/- 215 J, p < 0.01); the latter patients showed a trend (p < 0.10) to ward higher energy requirements than that of patients who received pla cebo. The incidence of asymptomatic bradyarrhythmias was higher in the propafenone group (28.9% vs, 7.1%, p < 0.02), but more patients who r eceived placebo had early recurrence of atrial fibrillation (16.7% vs. 0%, p < 0.02), Two days after cardioversion, more patients given prop afenone (73.5% vs. 52.9%, p < 0.05) were discharged from the hospital with sinus rhythm. During the in-hospital stay, propafenone was withdr awn from six patients (6.6%) because of side effects. Conclusions. Pro pafenone, given before electrical cardioversion for chronic atrial fib rillation does not affect the mean defibrillation threshold or the rat e of successful arrhythmia conversion. It decreases the recurrence of atrial fibrillation early after shock, thus allowing more patients to be discharged from the hospital with sinus rhythm.