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Temporal repolarization lability in hypertrophic cardiomyopathy caused by beta-myosin heavy-chain gene mutations

W L Atiga1, L Fananapazir, D McAreavey

  • 1Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.

Circulation
|March 22, 2000
PubMed

Insights

Patients with hypertrophic cardiomyopathy (HCM) caused by beta-myosin heavy-chain (beta-MHC) gene mutations show abnormal heart repolarization. This labile repolarization, identified by QT variability analysis, may increase their risk of sudden cardiac death.

Area of Science:

  • Cardiology
  • Genetics
  • Electrophysiology

Background:

  • Hypertrophic cardiomyopathy (HCM) linked to genetic mutations increases sudden death risk.
  • QT variability analysis is a tool for identifying high-risk patients with ventricular arrhythmias.
  • Beta-myosin heavy-chain (beta-MHC) gene mutations are a known cause of HCM.

Purpose of the Study:

  • To investigate if HCM patients with beta-MHC gene mutations exhibit labile ventricular repolarization.
  • To assess the utility of beat-to-beat QT variability analysis in these patients.
  • To correlate QT variability abnormalities with specific beta-MHC mutations.

Main Methods:

  • QT variability index and heart rate-QT interval coherence were measured using Holter monitors.
  • 36 patients with HCM due to beta-MHC mutations were studied.
  • 26 age- and sex-matched healthy individuals served as controls.

Main Results:

  • HCM patients exhibited significantly higher QT variability index compared to controls.
  • Patients with the Arg(403)Gln beta-MHC mutation showed the most pronounced QT variability abnormalities.
  • Lower heart rate-QT interval coherence was observed in HCM patients, particularly those with the Arg(403)Gln mutation.

Conclusions:

  • HCM patients with beta-MHC gene mutations demonstrate labile repolarization, suggesting an elevated risk of sudden death.
  • QT variability analysis can quantify repolarization abnormalities in HCM.
  • Specific beta-MHC mutations, like Arg(403)Gln, are associated with more severe QT variability, indicating a poorer prognosis.
Abstract

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