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Abnormal transmural repolarization process in patients with Brugada syndrome
Mutsuko Sangawa1, Hiroshi Morita, Takaaki Nakatsu
1Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine and Dentistry, Okayama City, Okayama, Japan.
Heart Rhythm
|July 28, 2009
Summary
Loss of rate-dependent repolarization dynamics, specifically QT dynamics, may contribute to ventricular fibrillation (VF) in Brugada syndrome (BrS) patients. This study investigated these repolarization abnormalities in BrS patients with and without VF.
Area of Science:
- Cardiology
- Electrophysiology
- Genetics
Background:
- Repolarization abnormalities during bradycardia are implicated in Brugada syndrome (BrS) ventricular fibrillation (VF) initiation.
- The specific role of rate-dependent repolarization dynamics in VF occurrence in BrS remains unclear.
Purpose of the Study:
- To compare rate-dependent repolarization dynamics between BrS patients with and without spontaneous VF.
- To investigate differences in these dynamics between BrS patients with and without SCN5A mutations.
Main Methods:
- Analysis of Holter recordings from 37 BrS patients (with and without VF) and 20 controls.
- Assessment of QT, QTp, and Tp-e interval relationships with RR intervals using linear regression.
- Comparison of QT/RR, QTp/RR, and Tp-e/RR slopes to evaluate rate-dependent repolarization sensitivity.
Main Results:
- The VF(+) group exhibited a loss of rate-dependent QT/RR and Tp-e/RR properties compared to VF(-) and control groups.
- No significant difference in QTp/RR slopes was observed across groups.
- The Tp-e interval showed a negative correlation with RR interval in the VF(+) group, unlike the positive correlation in other groups.
Conclusions:
- A loss of rate-dependent QT dynamics appears associated with the occurrence of VF in Brugada syndrome.
- SCN5A mutation status did not significantly influence the observed repolarization dynamics slopes.
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