Exon 3 deletion of ryanodine receptor causes left ventricular noncompaction, worsening catecholaminergic polymorphic ventricular tachycardia, and sudden cardiac arrest

Abstract

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a highly malignant genetic channelopathy associated with exertional syncope and reproducible polymorphic ventricular tachycardia with exercise. Approximately 65% of patients with CPVT are found to have a disease causing mutation in the RYR2 gene. RYR2 encodes a calcium ion transporter in the sarcomeric reticulum, and is responsible for the calcium induced calcium release that results in ventricular contraction. Recently, exon 3 deletion of RYR2 has been reported to be associated with left ventricular noncompaction. Herein we describe a patient with a novel, de novo deletion of exon 3 in the RYR2 gene that resulted in a severe CPVT phenotype and sudden cardiac arrest (SCA), and the development of left ventricular non-compaction (LVNC) coinciding with worsening arrhythmias. This case is unique in that the patient initially presented with exertional syncope and developed LVNC that coincided with increasingly severe ventricular arrhythmias and multiple episodes of SCA. This case supports the idea that RYR2 deletions cause a severe subtype of CPVT associated with LVNC and suggests LVNC may play a role in exacerbating the arrhythmias of CPVT. Deletion duplication testing should be considered in the context of CPVT and LVNC or SCA.

Keywords: RYR2; catecholaminergic polymorphic ventricular tachycardia; left ventricular noncompaction.