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Long QT Syndrome — RACP Paediatrics MCQ

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ModerateCardiologyLong QT SyndromeRACP Paediatrics

A 14-year-old girl collapses during a basketball game. CPR is commenced and an AED detects ventricular fibrillation. She is resuscitated successfully. She has no prior cardiac history. ECG post-resuscitation shows a corrected QT interval (QTc) of 520 ms. What is the most likely diagnosis?

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Correct answer: C — Long QT syndrome

A QTc >500 ms on a resting 12-lead ECG, in the context of a cardiac arrest during exercise, is highly suggestive of congenital long QT syndrome (LQTS). LQTS can cause torsades de pointes and ventricular fibrillation. Management includes beta-blockers, avoidance of QT-prolonging drugs, and consideration of an implantable cardioverter-defibrillator (ICD).

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Long QT Syndrome