Heart rate variability in patients with Brugada syndrome in Thailand

Aims Since patients with Brugada syndrome usually have symptoms at nighttime, we hypothesize that changes in autonomic modulation have an important rote in the occurrence of the ventricular fibrillation episodes. The objective of this study was to determine the changes in heart rate variability (HRV) in patients with Brugada syndrome compared to asymptomatic subjects with Brugada ECG and controls. Methods and results We studied 17 patients with Brugada syndrome, 10 asymptomatic subjects with Brugada ECG and 45 controls. Patients with Brugada syndrome and asymptomatic subjects with Brugada ECG underwent echocardiography, exercise stress testing, 24-h Hotter monitoring, signal-averaged ECG. Patients with Brugada syndrome also underwent coronary angiography and electrophysiologic study. Time domain and frequency domain HRV analysis were performed at daytime and nighttime. The results of this study showed that patients with Brugada syndrome had lower HRV or lower vagal tone at night compared to the controls. They also had tower heart rate during the day and higher during the night compared to asymptomatic subjects and the controls. Conclusion Patients with Brugada syndrome had tow heart rate variability at night which may predispose to the occurrence of VF episodes. (C) 2003 Published by Elsevier Ltd on behalf of The European Society of Cardiology.