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Long QT syndrome and life threatening arrhythmia in a newborn: molecular diagnosis and treatment response

E Schulze-Bahr1, H Fenge, D Etzrodt

  • 1Department of Cardiology and Angiology, Hospital of the University of Münster, D-48129 Münster, Germany. heart@uni-muenster.de

Heart (British Cardiac Society)
|December 17, 2003
PubMed

Insights

Congenital long QT syndrome in newborns with severe features can be treated effectively. Early genetic analysis and combination therapy with propranolol and mexiletine significantly reduced arrhythmias.

Area of Science:

  • Cardiology
  • Genetics
  • Neonatology

Background:

  • Congenital long QT syndrome (LQTS) presents significant cardiac risks in utero and neonatally, especially with atrioventricular block and marked QT prolongation (>600 ms).
  • Early-onset LQTS necessitates prompt diagnosis and management to mitigate severe cardiac events.

Observation:

  • A female newborn exhibited intrauterine and neonatal LQTS with atrioventricular block and QTc of 740 ms.
  • Initial treatment with propranolol showed partial improvement.

Findings:

  • High-throughput genetic analysis identified a sodium channel gene mutation (LQT3).
  • Adding mexiletine to propranolol resulted in complete arrhythmia resolution, disappearance of 2:1 atrioventricular block, and QTc shortening to 480 ms.
  • The therapeutic response, particularly the effect of mexiletine, suggested a genotype-related mechanism.

Implications:

  • Advanced genotyping can guide personalized treatment strategies for early-onset LQTS.
  • Combination therapy with propranolol and mexiletine offers a promising approach for managing severe LQT3 syndrome.
  • Long-term follow-up (1.5 years) confirmed sustained arrhythmia reduction, highlighting treatment efficacy.

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