Pronounced Late Potential at Night Time, Bradycardia, and Pronounced Vagal Activity May Be a Risk Marker of Ventricular Fibrillation in Brugada Syndrome

Abstract

Background: Ventricular Late Potential (LPs) detected signal averaged ECGs have been used widely to detect high risk patients. In Brugada syndrome (BrS), Ventricular fibrillation (VF) frequently occurs at nighttime and pronounced vagal activity. Purpose: We examine relationship between LPs and Heart rate, Vagal activity, and circadian variation of LPs in BrS. Methods: We evaluated 24 hours HolterECGs of total 14 BrS and 10 normal controls. We evaluated LPs (fQRS, LAS40, RMS40), RR interval and High frequency (HF: 0.15–0.4 Hz) of frequency domaine analysis. We examined relationship between LPs and RRinterval, LnHF. Results: Relationship between LAS40 and RRinterval, relationship between LAS40 and LnHF were obtained as a liner regression line and significant positive correlation in BrS. LAS40/RR slope was significantly sharpened in BrS with VF than BrS without VF, Controls (24±11 vs 3±13 vs −4±20, p<0.01, BrS with VF vs BrS without VF vs Controls). LAS40 at bradycardia was significantly pronounced in BrS with VF than BrS without VF, Controls (48±3 vs 32±12 vs 22±11, p<0.01, BrS with VF vs BrS without VF vs Controls). LAS40/LnHF slope were significantly sharpened than Controls. (3.0±3.2 vs −0.4±3.0, p<0.05, BrS vs Controls). Conclusion: In BrS, LPs were pronounced at bradycardia and night time and at pronounced vagal acitivity. Pronounced LPs at bradycardia and nighttime, at pronounced vagal acitivity may be a risk marker of VF in BrS.