Bradycardia-dependent ECG changes in Brugada syndrome

Area of Science:

• Cardiology
• Electrophysiology
• Medical Research

Background:

• Brugada syndrome (BS) is associated with ventricular fibrillation (VF), particularly during sleep.
• Bradycardia-dependent electrocardiogram (ECG) changes may influence nighttime VF occurrence in BS patients.

Purpose of the Study:

• To investigate differences in bradycardia-dependent ECG changes between symptomatic and asymptomatic Brugada syndrome patients.

Main Methods:

• Twenty-one BS patients were divided into symptomatic (n=9) and asymptomatic (n=12) groups.
• ECG changes were assessed at various RR intervals (400-1,100 ms) during electrophysiologic study.
• ST levels in V2 and QT intervals in V2 and V5 were measured.

Main Results:

• ST levels in V2 increased with RR interval prolongation in both groups, with no significant difference.
• QT interval prolongation was significantly smaller, and QT intervals at 1,100 ms were shorter in symptomatic BS patients compared to asymptomatic ones.

Conclusions:

• While ST elevation during bradycardia was similar in both groups, symptomatic BS patients showed inhibited QT interval prolongation.
• These distinct repolarization dynamics may explain the nighttime VF occurrence in BS patients during bradycardia.