Abstract 910: Catecholaminergic Polymorphic Ventricular Tachycardia: Genetics, Natural History and Response to Therapy

Abstract

Background: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmo-genic cardiac disease predisposing affected individuals to sudden cardiac death (SCD). Methods and Results: Here we provide data on the largest CPVT population thus far described. The study population consisted of 177 patients (64% female) of 93 families. All 93 probands (pbs) were screened for RYR2 mutations: 54 (58%) pbs carried a heterozygous RYR2 mutation, 1 pb a compound heterozygous RYR2 mutation and 3 pbs a homozygous (1), compound heterozygous (1) or heterozygous (1) CASQ2 mutation. One KCNJ2 mutation (T305I) was detected in a total of 15 pbs. In family members, another 40 RYR2 mutation carriers were identified. Only 29 of 95 gene carriers were phenotypically silent, therefore the penetrance of a RYR2 mutation was 69%. Of note, female sex was predominant among CPVT probands without a RYR2 mutation. Before the initiation of any treatment related to CPVT, 77 of 93 (83%) pbs experienced a cardiac e vent. Mean age of first event was 12±9 years. Neither sex nor the presence/absence of a RYR2 mutation was associated with a higher risk of developing events or with a younger age at onset of symptoms. Before therapy, 70% and 40% of 177 patients remained free of cardiac arrest and SCD before therapy by age 20 and 40 years, respectively. A history of juvenile SCD (<40 yrs) was present in 36% of families: the mean age of the lethal event was 18±9 yrs. One-hundred CPVT patients were initiated on β-blockers. On top, 41 patients were implanted with an ICD. During a mean follow-up time of 4.5±3 years, 28% of patients experienced a syncope (n=11), cardiac arrest (n=5) or appropriate ICD shock (n=12). Neither sex nor genotype was associated with a worse response to therapy. Conclusions: In this largest CPVT population reported so far, the presence/absence of a RYR2 mutation wasn’t associated with different clinical characteristics or response to therapy as compared to non-mutation carriers. CPVT remains a highly malignant disease with only a moderate response to β-blockers.