Sudden cardiac death and syncope of unknown origin: Think about catecholaminergic polymorphic ventricular tachycardia!

Abstract

Sudden cardiac death (SCD) or syncope may remain unexplained after extensive cardiac investigations. However, genetic testing may help to establish a clear diagnosis in a substantial proportion of these cases. We here report our experience in 5 patients referred for SCD or syncope of unknown origin, in whom the diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT) was given by genetic testing. The studied population encompasses 5 patients (3 females) mean age: 39.8 ± 12.3y (20–53y) of 5 different families. Age at first symptoms was 14.6 ± 9.2y (5–26y); a family history of syncope or SCD was present in 3 out of 5 patients and uncertain in 1 patient. Syncope was the first symptom in 4 patients and aborted SCD in 1 patient; it occurred mainly during stress or effort. Resting ECG was normal in 4 out of 5 patients and in only one patient showed polymorphic ESV. Structural cardiomyopathy was absent for all patients. Stress test triggered ventricular arrhythmias in 4 patients. When performed, Holter monitoring was irrelevant in 2/4 patients. Programmed ventricular stimulation was negative in 2/2 patients. The first medical diagnoses were: epilepsy, long QT syndrome for 2 patients, vaso-vagal syncope and SCD of unknown origin. Genetic testing performed 23.8 ± 11.5y (11–35y) after the initial event revealed mutation either in the RYR2, CASQ2 or KCNJ2 for all 5 patients. All patients are asymptomatic under drug treatment ± an implantable cardioverter defibrillator. In all cases, extensive familial screening has been proposed and is ongoing. In patients with SCD or syncope of unknown origin and normal anatomical heart, CPVT has to be considered as a potential cause even in patients with a normal stress test. Genetic testing should be more often considered in these patients to avoid missing this pathology, which is usually controlled with beta-blocking agents.