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Long QT syndrome — RACP Paediatrics MCQ

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ModerateCardiologyLong QT syndromeRACP Paediatrics

A 12-year-old boy collapses while swimming. There is a family history of sudden cardiac death in a cousin aged 20. Resting ECG shows a corrected QT interval of 520 ms. What is the most likely diagnosis?

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Correct answer: C — Long QT syndrome

Syncope during exercise (especially swimming) with a family history of sudden cardiac death and a prolonged QTc (>470 ms in males) is highly suspicious for long QT syndrome (LQTS), particularly LQT1. Beta-blocker therapy is the mainstay of treatment. Genetic testing and family screening are essential.

Reference: RCH Melbourne – 2023 – Syncope CPG; RACP Paediatric Curriculum – Cardiology