Exercise testing: the catecholaminergic polymorphic ventricular tachycardia crystal ball?

Abstract

This editorial refers to ‘The role of stress test for predicting genetic mutations and future cardiac events in asymptomatic relatives of catecholaminergic polymorphic ventricular tachycardia probands’ by M. Hayashi et al. , on page 1344 Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a fascinating inherited arrhythmia syndrome characterized by autosomal dominant transmission of adrenergically induced ventricular tachycardia (VT) associated with syncope and sudden death. First described clinically in the late 1970s,1,2 we have discovered many interesting insights about the disease over the past three decades. Clinical diagnosis is currently based on the observation of stress-induced polymorphic or bidirectional VT in the absence of structural heart disease or a prolonged QT interval.3 Diagnosis can be confirmed by the detection of mutations in the gene encoding the cardiac ryanodine receptor channel (RyR2) or the gene encoding cardiac calsequestrin (CASQ2) in ∼60% of symptomatic patients.4–7 Catecholaminergic polymorphic ventricular tachycardia has a malignant prognosis, with a recent study reporting an overall 8-year fatal or near-fatal event rate of 13%.8 Moreover, the same study reported an alarmingly high rate of arrhythmic events in asymptomatic relatives. However, CPVT appears to be a heterogenous disease that may have an age-dependent prognosis.8,9 As is often the case, early reports of rare syndromes typically report a dramatic course of the disease, and subsequent case finding unearths a spectrum of expression, including both asymptomatic phenotype carriers, and gene carriers with little or no phenotype. Beta-blocker therapy remains the cornerstone of treatment. However, a recent meta-analysis of 403 patients with 88% beta-blocker usage still reported an estimated 8-year fatal event rate of ∼6%.10 Therefore, an …