Abstract 13345: Relationship Between Parasympathetic Nervous System and QT Dynamics in Patients with Brugada Syndrome
Background: Brugada syndrome is an arrythmogenic disease characterized by a particular electrocardiogram pattern and an increased risk for sudden cardiac death due to ventricular tachyarrythmias. The ventricular tachyarrythmias usually occur at night, which is suggesting an influence of the autonomic nervous system. This study evaluated the changes in heart rate variability (HRV) and QT dynamics in patients with Brugada syndrome.
Methods: 20 patients with Brugada syndrome (B) (all men, age 48 years) and 43 patients for control group (C) (all men, age 53 years) were enrolled. HRV and the relationships between QT and RR intervals were analyzed from 24-hour Holter ECG data using automatic measurement system. Signal averaged waves from the vector magnitude lead were obtained by the summation of consecutive sinus beats during each 30-second period for 24 hours. QT were plotted against the corresponding mean RR interval and their slopes were calculated as QT-RR.
Results: The mean heart rate was low during night in B (B 58.9±6.7 vs C 64.0±8.9, p<0.05). In HRV parameter HF was high during night in B (HF (Ln) ; B 5.31±0.77 vs C 4.59±1.13, p<0.05). QT-RR was less steeper during night in B compared with C (QT-RR; B 0.11±0.03 vs C 0.13±0.05, p<0.05). There was a strong correlation between HF and QT-RR (correlation coefficient −0.53, p<0.0001) during night. Brugada patients include 15 symptomatic (sym) and 5 asymptomatic (asym) patients. QT-RR during 24-hour and night in symptomatic patients was less steeper than asymptomatic patients (24-hour; sym 0.132±0.036 vs asym 0.171±0.029, p<0.05, night ; sym 0.096±0.023 vs asym 0.127±0.031, p<0.05).
Conclusion: Parasympathetic nervous system during night was more dominant in Brugada syndrome and might affect the QT-RR dynamics. Brugada patients might have a unique autonomic nervous system and modulation of the repolarization. It might bring the frequent occurrence of ventricular fibrillation in Brugada patients at night. And we may use QT-RR as a risk stratification of ventricular fibrillation for Brugada patients.
- © 2010 by American Heart Association, Inc.