Dose-Response Effect of Flecainide in Patients With Symptomatic Paroxysmal Atrial Fibrillation and/or Flutter Monitored With Trans-Telephonic Electrocardiography A Multicenter, Placebo-Controlled, Double-Blind Trial

BACKGROUND: A double-blind, randomized, parallel-group, placebo-controlled trial was conducted in patients with paroxysmal atrial fibrillation or flutter (PAF/PAFL) experiencing 2 or more episodes of symptomatic PAF/PAFL during a 28-day observation period to determine the dose-response effect and safety of flecainide. METHODS AND RESULTS: A total of 143 patients at 30 centers were randomized to receive 25, 50, or 100 mg of flecainide or placebo twice daily (BID). In 123 patients (per protocol set), those remaining free from PAF/PAFL after the treatment were 3.1% on placebo, 7.7% on 25 mg/BID, 9.4% on 50 mg/BID, and 39.4% on 100 mg/BID of flecainide. As a whole group, a significant linear dose-response (p<0.001) was observed and a significant difference between placebo and 100 mg/BID was observed (p<0.001). A similar dose-response between the present study and Caucasian study was demonstrated. Although there were 5 patients who needed cardioversion or ablation because of frequent episodes of PAF/PAFL (2 in 25 mg/BID, 1 in 50 mg/BID, and 2 in 100 mg/BID of flecainide), neither death nor ventricular proarrhythmic event was reported. CONCLUSIONS: This study indicated that flecainide exerted a significant dose-dependent effect on the prevention of symptomatic PAF/PAFL recurrence and showed that there was no inter-ethnic difference in the clinical effect of flecainide in patients with PAF/PAFL.