A 12-year-old girl presents with exertional syncope. Resting ECG, echocardiogram, and electrolytes are all normal. Exercise testing reproduces polymorphic ventricular tachycardia with alternating QRS axis (bidirectional VT) at peak effort, which resolves with rest. Family history reveals a sibling with similar episodes. What is the first-line therapy?
- A Flecainide monotherapy
- B Beta blocker therapy ✓
- C Implantable cardioverter-defibrillator alone
- D High-dose verapamil
Explanation
Exertion-triggered bidirectional VT 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. Beta blockers are first line and markedly reduce events. Flecainide is an add-on when beta blockers fail, and ICD implantation is reserved for patients with aborted cardiac arrest or breakthrough events on maximal therapy because inappropriate shocks can themselves trigger catecholamine-driven storms in children.
Reference: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 12th ed.
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