Propafenone treatment of symptomatic paroxysmal supraventricular arrhythmias. A randomized, placebo-controlled, crossover trial in patients tolerating oral therapy.

OBJECTIVE

To test the hypothesis that propafenone, administered orally, prevents symptomatic paroxysmal supraventricular arrhythmias.

DESIGN

a 6-month, open-label, dose-finding phase followed by a randomized, double-blind, placebo-controlled, crossover phase, with each treatment period lasting up to 60 days.

SETTING

An outpatient clinic.

PATIENTS

Thirty-three patients with either paroxysmal supraventricular tachycardia (n = 16) or paroxysmal atrial fibrillation (n = 17) were enrolled. Their arrhythmias were documented by electrocardiogram before enrollment. Twenty-three patients (14 with paroxysmal supraventricular tachycardia and 9 with paroxysmal atrial fibrillation) were randomized and the data obtained from these patients were used in the efficacy analysis.

INTERVENTION

Propafenone (300 mg three times daily in 19 patients, 300 mg twice daily in 3 patients, and 150 mg twice daily in 1 patient) and matching placebo tablets were administered in a randomized sequence.

MEASUREMENTS

Symptomatic arrhythmia was documented by telephone transmission of the electrocardiogram.

MAIN RESULTS

The time to first recurrence was prolonged for the overall group of 23 patients while they received propafenone (P = 0.004). The recurrence rate of arrhythmia during treatment with propafenone was estimated to be approximately one fifth of the recurrence rate during treatment with placebo.

CONCLUSIONS

Propafenone is effective in reducing symptomatic paroxysmal supraventricular arrhythmias.