A 14-year-old boy has two episodes of syncope during football matches. Resting ECG, echocardiogram and Holter are all normal. An exercise treadmill test reproduces polymorphic ventricular tachycardia with alternating QRS axis (bidirectional VT) at peak exertion, resolving with rest. Family history reveals a cousin who died suddenly during sports. What is the most likely diagnosis?
- A Long QT syndrome Type 1
- B Arrhythmogenic right ventricular cardiomyopathy
- C Catecholaminergic polymorphic ventricular tachycardia ✓
- D Brugada syndrome
Correct answer: C. Catecholaminergic polymorphic ventricular tachycardia
Explanation
Exertion-triggered bidirectional VT with a structurally normal heart and normal resting QT interval is the signature of catecholaminergic polymorphic VT, usually from RYR2 mutations causing abnormal sarcoplasmic reticulum calcium release. LQT1 also causes exertional arrhythmia but shows QTc prolongation. Brugada has a coved ST pattern and rest/nocturnal events, and ARVC shows structural RV changes and epsilon waves, all absent here. Beta blockers are the mainstay of therapy.
Reference: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 12th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.