Abnormal transmural repolarization process in patients with Brugada syndrome.
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.
Sangawa
Mutsuko
M
Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine and Dentistry, Okayama City, Okayama, Japan.
Morita
Hiroshi
H
Nakatsu
Takaaki
T
Nishii
Nobuhiro
N
Miura
Daiji
D
Miura
Aya
A
Tada
Takeshi
T
Murakami
Masato
M
Hiramatsu
Shigeki
S
Nagase
Satoshi
S
Nakamura
Kazufumi
K
Oka
Takefumi
T
Toyonaga
Shinji
S
Mashima
Keiichi
K
Kusachi
Shozo
S
Yamamoto
Kazuhide
K
Ohe
Tohru
T
Kusano
Kengo F
KF
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
D009124:Muscle Proteins; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels