Catecholaminergic Polymorphic Ventricular Tachycardia and Gene Therapy: A Comprehensive Review of the Literature

Abstract

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited channelopathy. In this review, we summarize the epidemiology, pathophysiology, clinical characteristics, diagnostics, genetic mutations, standard treatment, and the emergence of potential gene therapy. This inherited cardiac arrhythmia presents in a bimodal distribution with no association between sex or ethnicity. Six different CPVT genes have been identified, however, most of the cases are related to a heterozygous, gain-of-function mutation on the ryanodine receptor-2 gene (RyR2) and calsequestrin-2 gene (CASQ2) that causes delayed after-depolarization. The diagnosis is clinically based, seen in patients presenting with syncope after exercise or stress-related emotions, as well as cardiac arrest with full recovery or even sudden cardiac death. Standard treatment relies on beta-blockers, with add-on therapy, flecainide, and cardiac sympathetic denervation as second-line treatments. An implantable cardioverter-defibrillator is indicated for patients who have suffered a cardiac arrest. Potential gene therapy has emerged in the last 20 years and accelerated because of associated viral vector application in increasing the efficiency of prolonged cardiac gene expression. Nevertheless, human trials for gene therapy for CPVT have been limited as the population is rare, and an excessive amount of funding is required.

Keywords: arrhythmia; catecholaminergic polymorphic ventricular tachycardia; channelopathy; gene therapy; tachycardia.

Figure 1. Ryanodine receptor-2 (RyR2) receptors under physiologic conditions release calcium from intracellular stores during the excitation-contraction process in cardiac muscles. Mutation of the RyR receptor causes structural changes in the protein, releasing an abnormal amount of calcium and producing arrhythmias in the presence of stimuli such as stress or emotions.

SR: sarcoplasmic reticulum; RyR2: ryanodine receptor-2; CPVT: catecholaminergic polymorphic ventricular tachycardia Figure created by using BioRender.com