Effectiveness of Flecainide in a Catecholaminergic Polymorphic Ventricular Tachycardia Patient with Cardiac Ryanodine Receptor Gene（RyR2） Mutation： A Case Report

Abstract

Catecholaminergic polymorphic ventricular tachycardia（ CPVT） is one of the cardiacchannelopathies that appears during childhood and is associated with a poor prognosis. Mutations of the cardiac ryanodine receptor gene（ RyR2） have been identified as one of its causes. An abnormal function of the cardiac ryanodine receptor produces an excessive release of calcium ions from the sarcoplasmic reticulum, and this calcium overload causes arrhythmias due to triggered activity. A recent study demonstrated the efficacy of flecainide in genetically positive CPVT patients. Flecainide is a class Ic sodium channel blocker and a direct suppressor of the cardiac ryanodine receptor.
Here, we report the case of a 10-year-old boy with a normal heart who developed syncope during physical stress. The patient?s resting electrocardiogram（ ECG） demonstrated sinus bradycardia with a normal QT interval. The treadmill stress test and Holter ECG demonstrated polymorphic ventricular tachycardia and supraventricular（ atrial or junctional） tachycardia. Therefore, he was diagnosed with CPVT. We recommended that the patient avoid competitive sports and prescribed propranolol at a dosage of 2 mg/kg per day and flecainide that titrated up to 150 mg/m2 per day. Flecainide demonstrated dosage-dependent amelioration of ventricular arrhythmia and suppressed supraventricular ectopies. The patient did not experienced syncope or any other complications during the 1-year follow-up period. He had previously reported causative missense mutation in RyR2 （c.14311 G>A p. V4771I）.
Combination therapy of flecainide and a beta-blocker is safe and effective for supraventricular and ventricular tachycardia in patients with the RyR2 mutation. This therapy may improve prognosis in CPVT patients.