Torsades de pointes complicating atrioventricular block: Evidence for a genetic predisposition

Philippe Chevalier*, Chloé Bellocq, Gilles Millat, Eric Piqueras, Franck Potet, Jean Jacques Schott, Isabelle Baró, Hervé Lemarec, Jacques Barhanin, Robert Rousson, Claire Rodriguez-Lafrasse

*Corresponding author for this work

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Background: The prevalence of genetic risk factors has not been systematically evaluated in the setting of complete atriventricular (AV) block complicated by long QT syndrome (LQTS). Objective: This study was performed to determine to what extent acquired LQTS in the context of AV block has a genetic substrate. Methods: Among 420 recipients of pacemakers implanted over a 3-year period, we identified retrospectively 29 patients with complete AV block and a QT interval >600 ms in duration. A second study group included 22 randomly selected patients who had AV block and a QT interval <600 ms. Normal controls were 100 consecutive individuals without medical history. Genetic studies screening for HERG, KCNQ1 KCNE1, KCNE2, and SCN5A mutations were performed. Results: We identified four mutations on genes encoding potassium channels in five patients with AV block and acquired LQTS. These mutations were not found among patients with AV block and a QT interval <600 ms in duration or in healthy volunteers. Functional expression of three HERG mutations (R328C, R696C, and R1047L) had a dominant negative effect on wild-type IKr. One KCNE2 mutation (R77W) identified in a patient treated with flecainide did not alter IKr. Conclusions: This study showed that complete AV block complicated by LQTS was associated with HERG mutations in 17% of cases. Further studies are needed to identify factors, genetic or environmental, which may be implicated in bradycardia-related abnormalities of ventricular repolarization.

Original languageEnglish (US)
Pages (from-to)170-174
Number of pages5
JournalHeart Rhythm
Volume4
Issue number2
DOIs
StatePublished - Feb 1 2007

Keywords

  • Atrioventricular block
  • HERG mutation
  • Long QT interval
  • Torsades de pointes

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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    Chevalier, P., Bellocq, C., Millat, G., Piqueras, E., Potet, F., Schott, J. J., Baró, I., Lemarec, H., Barhanin, J., Rousson, R., & Rodriguez-Lafrasse, C. (2007). Torsades de pointes complicating atrioventricular block: Evidence for a genetic predisposition. Heart Rhythm, 4(2), 170-174. https://doi.org/10.1016/j.hrthm.2006.10.004