A 14-year-old boy with two episodes of exertional syncope has an entirely normal resting ECG and echocardiogram. During treadmill testing he develops bidirectional ventricular tachycardia. Family history reveals a cousin who died suddenly during swimming. Which diagnosis fits best?

• A Catecholaminergic polymorphic ventricular tachycardia ✓
• B Arrhythmogenic right ventricular cardiomyopathy
• C Brugada syndrome
• D Wolff-Parkinson-White syndrome

Explanation

Bidirectional VT during exercise stress with a structurally normal heart and normal resting ECG defines catecholaminergic polymorphic VT, usually from autosomal dominant RYR2 mutations causing abnormal sarcoplasmic reticulum calcium release. First-line treatment is beta blockade, with an ICD added for high-risk patients. Brugada shows a characteristic coved ST elevation at rest, ARVC shows epsilon waves and right ventricular structural change, and WPW shows delta waves, so all three are excluded by the findings.

Reference: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 12th ed.

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