Sodium channel blockers enhance the temporal QT interval variability in the right precordial leads in Brugada syndrome.
BACKGROUND
Temporal QT interval variability is associated with sudden cardiac death. The purpose of this study was to evaluate temporal QT interval variability in Brugada syndrome (BS).


METHODS
We measured QT and RR intervals in precordial leads (V(1)-V(6)) based on 12-beat resting ECG recordings from 16 BS patients (B group) with spontaneous ST elevation in right precordial leads (V(1)-V(2)) and from 10 patients with normal hearts (C group). We measured the response in B group before and after administration of pilsicainide (1 mg/kg). The standard deviation (QT-SD, RR-SD) of the time domain and total frequency power (QT-TP, RR-TP) were calculated for all precordial leads, and the latter was to analyze the frequency domain.


RESULTS
The right precordial leads in BS exhibited an additional and prominent ST elevation (coved-type) after pilsicainide administration. Both QT-SD and QT-TP values were significantly more increased in B, than in C (5.1 +/- 1.2 vs 3.6 +/- 0.2 and 23.4 +/- 2.9 vs 12.3 +/- 1.7 msec(2), P < 0.01, respectively) and after pilsicainide administration in B. (5.1 +/- 0.4 vs 3.9 +/- 0.3, 25.8 +/- 3.4 vs 16.3 +/- 2.6 msec(2), P < 0.01, respectively) However, QT-SD and QT-TP did not significantly change in any of other leads (V(3)-V(6)) and RR-SD and RR-TP were similar for both groups, as well as after intravenous pilsicainide administration in B.


CONCLUSIONS
The temporal QT interval variability was identified in BS. Moreover, sodium channel blocker induced temporal fluctuation in QT interval and it may possibly provide a substrate for ventricular arrhythmia in BS patients.
Kanemori
Tetsuzou
T
Department of Internal Medicine, Division of Coronary Heart Disease, Hyogo College of Medicine, Nishinomiya, Japan. kinchan@hyo-med.ac.jp
Shimizu
Hiroki
H
Oka
Katsumi
K
Furukawa
Yoshio
Y
Hiromoto
Kenji
K
Mine
Takanao
T
Masuyama
Tohru
T
Ohyanagi
Mitsumasa
M
D053840:Brugada Syndrome / Q000175:diagnosis / Q000503:physiopathology*; D004562:Electrocardiography / Q000187:drug effects* / Q000379:methods; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D013997:Time Factors
D026941:Sodium Channel Blockers; D008012:Lidocaine; C042288:pilsicainide