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Athlete ECG Interpretation — EECC MCQ

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HardGeneral CardiologyAthlete ECG InterpretationEECC

A patient with genetically confirmed long-QT syndrome type 3 has recurrent nocturnal events despite an appropriate beta-blocker. During a supervised test, mexiletine shortens QTc by 55 ms. What is the genotype-directed next pharmacological step?

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Correct answer: E — Add mexiletine while continuing beta-blocker therapy

LQT3 usually reflects a gain of late sodium current. Mexiletine can shorten QTc and reduce events in responsive variants and is added to established beta-blockade under specialist supervision. Sotalol prolongs QT, flecainide and verapamil are not the standard response-tested treatment, and nocturnal events remain clinically important.

Reference: 2022 ESC Guidelines for ventricular arrhythmias and sudden cardiac death. https://academic.oup.com/eurheartj/article/43/40/3997/6675633