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

Backgrond: 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 24hours HolterECGs of total 14 BrS and 10 normal controls. We evaluated LPs (fQRS,LAS40,RMS40), RR interval and High frequency (HF:0.15-0.4Hz) 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 inBrS. LAS40/RRslope was significantly sharpened in BrSwithVF than BrSwithout VF, Controls (24 ±11 vs 3±13 vs -4±20, p<0.01, BrSwithVF vs BrSwithoutVF vs Controls). LAS40 at bradycardia was significantly pronounced in BrS withVF than BrS withoutVF, Controls (48±3 vs 32±12 vs 22±11, p<0.01, BrS withVF vs BrS withoutVF vs Controls). LAS40/LnHFslope 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 vagalacitivity may be a risk marker of VF inBrS.