Flecainide Acetate Prevents Recurrence of Symptomatic Paroxysmal Supraventricular Tachycardia

Oral flecainide acetate was administered to 34 patients with documented symptomatic paroxysmal supraventricular tachycardia (PSVT) with a double-blind, placebo-controlled, 8-week crossover trial design. PSVT was defined as a regular tachycardia of at least 120 beats/min without evidence of atrioventricular dissociation. The study required considerable patient cooperation. Patients first entered a 4-week qualifying phase followed by a 3-week, open label, flecainide dose-ranging phase. They were then randomized in a blind fashion to receive either placebo or tolerated flecainide dose for an 8-week treatment period and then crossed over after four symptomatic documented episodes of PSVT or at the end of the treatment period. By all efficacy parameters analyzed, flecainide was superior to placebo. Flecainide was associated with an actuarial 79%o freedom from symptomatic PSVT events compared with only 15% on placebo at 60 days (p<0.001). Of the 34 patients, 29 had recurrence of symptomatic PSVT at least once during the placebo phase; only eight patients had a recurrence during the flecainide phase (p<0.001). The median time to the first symptomatic PSVT event was 11 days in the placebo group and greater than 55 days in the flecainide group (p<0.001). Likewise, the interval between attacks was a median of 12 days on placebo compared with more than 55 days on flecainide (p<0.001). Finally, the fiecainide slowed symptomatic PSVT heart rates to 143±12 beats/min from 178±12 on placebo (p<0.02) in the seven patients who had events in the placebo and flecainide treatment phases. In summary, flecainide significantly reduces the likelihood of symptomatic PSVT recurrences, and it, therefore, is an effective agent in patients who have symptomatic PSVT. (Circulation 1991;83:119-125)