Flecainide for Catecholaminergic Polymorphic VT
Is the combination of flecainide and a beta-blocker more efficacious than a beta-blocker alone for prevention of ventricular arrhythmias (VAs) in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT)?
The subjects of this study were 13 patients (median age 16 years) with CPVT who had undergone implantable cardioverter-defibrillator implantation. After undergoing a baseline exercise test while being treated with a maximally tolerated dose of a beta-blocker, they were randomly assigned in single-blind fashion to treatment with flecainide or placebo for 3 months, followed by another exercise test. Treatment with the beta-blocker was continued throughout the study. The patients then crossed over to the alternate therapy and again underwent exercise testing after 3 months of therapy. The primary endpoint was VAs induced by exercise.
The median flecainide dose was 300 mg/day. The percentage of patients with exercise-induced nonsustained VT was significantly lower during treatment with flecainide/beta-blocker compared with placebo/beta-blocker (0 vs. 33%). The percentage of patients with no ectopy at all was significantly higher during treatment with flecainide/beta-blocker compared with placebo/beta-blocker (83% vs. 25%). Mild side effects attributable to flecainide occurred in five patients.
The combination of flecainide and a beta-blocker is superior to a beta-blocker alone for suppression of exercise-induced VAs in patients with CPVT.
Flecainide suppresses sarcoplasmic reticulum calcium release, the primary trigger for VAs in CPVT, and already is used fairly commonly in patients with CPVT. However, the evidence of efficacy has been limited to open-label cohort studies. The present study was small (due to the rarity of CPVT) but very well designed and provides robust evidence supporting the use of flecainide in combination with a beta-blocker.
Keywords: Adrenergic beta-Antagonists, Arrhythmias, Cardiac, Defibrillators, Implantable, Exercise Test, Flecainide, Maximum Tolerated Dose, Primary Prevention, Tachycardia, Ventricular
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