Atrial electrophysiological and structural remodeling in high-risk patients with Brugada syndrome: assessment with electrophysiology and echocardiography.
BACKGROUND
Atrial fibrillation (AF) often occurs in Brugada syndrome (BrS), and BrS patients with spontaneous AF often experience ventricular fibrillation (VF) attacks. Atrial vulnerability providing a substrate for AF is known to be enhanced in BrS, but there are no data on atrial structural attributes.


OBJECTIVE
The objective of this study was to assess atrial electrophysiological and structural characteristics in BrS and their relationships with gene mutations.


METHODS
We studied 57 patients with BrS. Intra-atrial conduction time (CT) was defined as the interval from the stimulus at the high right atrium to atrial deflection at the distal portion of the coronary sinus. Left atrial volume index (LAVI) was measured by the modified Simpson method at left ventricular end-systole using echocardiography. SCN5A mutations were analyzed in all patients.


RESULTS
In patients with documented VF, spontaneous AF frequently occurred and prolonged CT and increased LAVI were observed compared with those in patients without VF (all P < .05; LAVI: 22 +/- 5 vs. 32 +/- 7 ml/m(2)). Even among patients without AF, CT and LAVI were still increased in patients with VF (all P < .05; LAVI: 22 +/- 5 vs. 29 +/- 5 ml/m(2)). The presence of SCN5A mutation was associated with prolonged CT (P < .05) and increased LAVI (P < .01), but not with arrhythmic episodes.


CONCLUSIONS
Both atrial vulnerability and structural remodeling are enhanced in high-risk patients with BrS, even in those without AF. These morphological characteristics suggest that BrS is a form of genetic myocardial disease.
Toh
Norihisa
N
Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan. nori-t@fd5.sonet.ne.jp
Morita
Hiroshi
H
Nagase
Satoshi
S
Taniguchi
Manabu
M
Miura
Daiji
D
Nishii
Nobuhiro
N
Nakamura
Kazufumi
K
Ohe
Tohru
T
Kusano
Kengo F
KF
Ito
Hiroshi
H
D001281:Atrial Fibrillation / Q000000981:diagnostic imaging* / Q000235:genetics / Q000503:physiopathology*; D053840:Brugada Syndrome / Q000000981:diagnostic imaging* / Q000235:genetics / Q000503:physiopathology*; D016009:Chi-Square Distribution; D017147:Defibrillators, Implantable; D004452:Echocardiography / Q000379:methods*; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000235:genetics; D062554:NAV1.5 Voltage-Gated Sodium Channel; D015222:Sodium Channels / Q000235:genetics
D009124:Muscle Proteins; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels