A 12-year-old boy has recurrent exertional syncope. Resting ECG, echocardiography, and cardiac MRI are all normal. Holter monitoring is unremarkable. During treadmill testing he develops polymorphic ventricular tachycardia with alternating QRS axis. His sister died suddenly at age 14 with a reportedly normal ECG. What is the most likely diagnosis?

• A Long QT syndrome type 1
• B Catecholaminergic polymorphic ventricular tachycardia ✓
• C Brugada syndrome
• D Wolff-Parkinson-White syndrome

Explanation

CPVT produces exercise-induced bidirectional or polymorphic VT with a structurally normal heart and a completely normal resting ECG and normal QTc, which excludes long QT syndrome type 1 where the resting QTc is always prolonged. It is caused by ryanodine receptor mutations causing calcium leak, and first-line treatment is nadolol or propranolol, often combined with flecainide, with an ICD for drug-refractory cases. Bidirectional VT on stress testing is the signature finding.

Reference: Park's Pediatric Cardiology for Practitioners, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.