Clinical and Molecular Characterization of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia

TLDR

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disorder caused by mutations in the cardiac ryanodine receptor gene (RyR2), yet the prevalence of RyR2 mutations and the distinct clinical features of RyR2‑positive versus nongenotyped CPVT remain undefined. The study evaluated 30 probands and 118 family members with stress‑induced polymorphic ventricular arrhythmias in structurally normal hearts, performing clinical phenotyping and RyR2 gene mutation screening. RyR2 mutations were found in 47% of probands and 9 family members, with affected patients experiencing earlier arrhythmic events and a higher syncope risk in males; CPVT presents heterogeneously beyond childhood, β‑blockers reduce arrhythmias but 30% require ICDs, and the data support early evaluation and treatment of young men carrying RyR2 mutations.

Abstract

Background — Mutations in the cardiac ryanodine receptor gene ( RyR2 ) underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmogenic disease occurring in the structurally intact heart. The proportion of patients with CPVT carrying RyR2 mutations is unknown, and the clinical features of RyR2 -CPVT as compared with nongenotyped CPVT are undefined. Methods and Results — Patients with documented polymorphic ventricular arrhythmias occurring during physical or emotional stress with a normal heart entered the study. The clinical phenotype of the 30 probands and of 118 family members was evaluated, and mutation screening on the RyR2 gene was performed. Arrhythmias documented in probands were: 14 of 30 bidirectional ventricular tachycardia, 12 of 30 polymorphic ventricular tachycardia, and 4 of 30 catecholaminergic idiopathic ventricular fibrillation; RyR2 mutations were identified in 14 of 30 probands (36% bidirectional ventricular tachycardia, 58% polymorphic ventricular tachycardia, 50% catecholaminergic idiopathic ventricular fibrillation) and in 9 family members (4 silent gene carriers). Genotype-phenotype analysis showed that patients with RyR2 CPVT have events at a younger age than do patients with nongenotyped CPVT and that male sex is a risk factor for syncope in RyR2 -CPVT (relative risk=4.2). Conclusions — CPVT is a clinically and genetically heterogeneous disease manifesting beyond pediatric age with a spectrum of polymorphic arrhythmias. β-Blockers reduce arrhythmias, but in 30% of patients an implantable defibrillator may be required. Genetic analysis identifies two groups of patients: Patients with nongenotyped CPVT are predominantly women and become symptomatic later in life; patients with RyR2 CPVT become symptomatic earlier, and men are at higher risk of cardiac events. These data provide a rationale for prompt evaluation and treatment of young men with RyR2 mutations.