title: Abnormal transmural repolarization process in patients with Brugada syndrome.
abstract: BACKGROUND
  Repolarization abnormality, especially during bradycardia, might be critical for initiation of ventricular fibrillation (VF) in patients with Brugada syndrome (BrS), but the contribution of the rate-dependent repolarization dynamics to the occurrence of VF is still unknown.
  
  
  OBJECTIVE
  The aim of our study was to determine the differences in rate-dependent repolarization dynamics between BrS with and without spontaneous VF and between BrS with and without SCN5A mutation.
  
  
  METHODS
  The subjects were 37 BrS patients with VF (VF(+) group: 10 male subjects) and without VF (VF(-) group: 27 male subjects) and 20 control subjects. Genetic analysis of SCN5A was performed in all 37 BrS patients. The relationships between QT, QTp, Tp-e, and RR intervals were obtained from Holter recordings as first linear regression lines, and the slopes of QT/RR, QTp/RR, and Tp-e/RR linear regression lines as the sensitivity of rate-dependent repolarization dynamics were compared.
  
  
  RESULTS
  QT/RR and Tp-e/RR slopes showed loss of a rate-dependent property in the VF(+) group compared with those in the VF(-) and control groups. There was no significant difference in QTp/RR slope among the VF(+), VF(-) and control groups. The Tp-e interval had a negative correlation with the RR interval in the VF(+) group and a positive correlation with the RR interval in the VF(-) and control groups. There was no significant difference in QT/RR, QTp/RR, and Tp-e/RR slopes between BrS patients with SCN5A mutation and those without SCN5A mutation.
  
  
  CONCLUSIONS
  Loss of rate-dependent QT dynamics may be associated with occurrence of VF in BrS.
authors.affiliation: Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine and Dentistry, Okayama City, Okayama, Japan.
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Sangawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morita
authors.forename: Takaaki
authors.initials: T
authors.lastname: Nakatsu
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishii
authors.forename: Daiji
authors.initials: D
authors.lastname: Miura
authors.forename: Aya
authors.initials: A
authors.lastname: Miura
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tada
authors.forename: Masato
authors.initials: M
authors.lastname: Murakami
authors.forename: Shigeki
authors.initials: S
authors.lastname: Hiramatsu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagase
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takefumi
authors.initials: T
authors.lastname: Oka
authors.forename: Shinji
authors.initials: S
authors.lastname: Toyonaga
authors.forename: Keiichi
authors.initials: K
authors.lastname: Mashima
authors.forename: Shozo
authors.initials: S
authors.lastname: Kusachi
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohe
authors.forename: Kengo F
authors.initials: KF
authors.lastname: Kusano
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D053840:Brugada Syndrome / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D016022:Case-Control Studies; D015716:Electrocardiography, Ambulatory; D006801:Humans; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000235:genetics*; D062554:NAV1.5 Voltage-Gated Sodium Channel; D015222:Sodium Channels / Q000235:genetics*; D013223:Statistics as Topic; D014693:Ventricular Fibrillation / Q000235:genetics / Q000503:physiopathology
chemical_list: D009124:Muscle Proteins; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels