Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare inherited heart rhythm disorder in which dangerous arrhythmias are triggered specifically by physical exertion or emotional stress. Unlike most arrhythmia conditions where problems arise at rest, CPVT is characterised by ventricular arrhythmias that appear only when catecholamines (adrenaline and related stress hormones) are released during exercise or excitement.
CPVT is most commonly caused by mutations in the ryanodine receptor gene (RYR2), which encodes a calcium channel in heart muscle cells. In a normal heart, calcium release during each heartbeat is tightly controlled; in CPVT, the abnormal receptor allows excessive calcium leakage from intracellular stores during stress, generating dangerous electrical impulses in the ventricles. The hallmark is bidirectional ventricular tachycardia (VT), visible on exercise ECG, where the QRS complex direction alternates with each beat. Crucially, the resting ECG and echocardiogram are typically completely normal.
CPVT most commonly presents in children and teenagers as unexplained exercise-induced syncope (fainting), seizures misdiagnosed as epilepsy, or sudden cardiac arrest during physical activity. It is frequently missed because the heart appears structurally normal on all standard investigations. An exercise stress test or catecholamine infusion test is needed to provoke the arrhythmia, and genetic testing can confirm the diagnosis and enable cascade family screening.
Beta-blockers (particularly nadolol) are the cornerstone of treatment. Flecainide is added when breakthrough symptoms occur on beta-blockers alone. Competitive sport and strenuous exercise are restricted. An ICD is recommended for those who have survived cardiac arrest, and sometimes prophylactically in high-risk patients despite optimal medical therapy.