ECG Case 104: Congenital Long QT Syndrome

ECG Interpretation

  • Sinus rhythm, rate 75/min
  • Normal PR interval and QRS complex duration
  • Normal axis
  • Normal QRS complexes
  • Inverted T waves in leads V1–V3
  • Long QT interval (520 ms)

Congenital Long QT Syndrome
Congenital Long QT Syndrome

Clinical Interpretation

A collapse during exercise raises the possibility of aortic stenosis, hypertrophic cardiomyopathy, or an exercise-induced arrhythmia. This ECG does not show the pattern of left ventricular hypertrophy, so aortic stenosis is unlikely.

Anterior T wave inversion is characteristic of hypertrophic cardiomyopathy, but this does not normally cause a prolonged QT interval. Exercise-induced arrhythmias are typical of the familial long QT syndrome, and this boy’s sister had died suddenly.

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What to do ?

Initial treatment is with a beta-blocker, but an ICD (implantable cardioverter defibrillator) must be considered.