Dominant frequency of ventricular fibrillation can be one of predictive values to discriminate high risk patients with Brugada syndrome

Abstract

Purpose: Recent European and Japanese studies showed the induction of ventricular fibrillation (VF) during electrophysiological stimulation test (EPS) could not predict the sudden cardiac death in patients with Brugada syndrome (BrS). However, some recent studies indicated that the shortness of effective refractory period (ERP) or the mode of induction of VF might be good predictive value. Those indicated the exist of inherent electrical substrates in high risk patients with BrS. We accessed VF cycle length as the dominant frequency (DF) obtained by a fast Fourier transformation (FFT) analysis. Methods: The induced VF recorded from RV apex (RVA) and RV outflow tract (RVOT) was performed with a 4096 point-FFT analysis in 28 patients (all male, 51±14 years old) with BrS. DF was obtained by Fast Fourier transform from 4-s data (phase) and sequentially every 2 s before cardioversion. The average of DF from intracardiac electrograms were compared between the symptomatic group (n=15) and the asymptomatic group (n=13). EPS was performed during isoproterenol (ISP) and after propranolol (PRO) in selected patients. Results: The DF had a weak negative correlation to ERP. The relationship of DF between RVA and RVOT had a very good correlation in all phases. The DF significantly increased from phase 1 to 6 (p<0.003; 5.72±0.36 Hz to 6.19±0.49 Hz). The DFs were significantly higher in symptomatic group than in asymptomatic group (p=0.012). ISP significantly (p<0.05) shorten ERP of RV and prevented induction of VF in 20 of 25 patients (80%). During ISP, 5 patients experienced induction of VF. ISP significantly influenced DF transition compared with the control state. DF gradually increased but was unchanged after the middle phase. PRO induced VF in 5 (83.3%) of 6 patients who tested negative during ISP. DF after PRO was higher than that in the corresponding phase in the control state. ISP suppressed the induction of VF and the increase of DF with time. PRO aggravated VF and accelerated DF. Those pharmacological results were not inconsistent with the previous reports. Conclusions: Those data suggested that the DF of VF in patients with BrS was related to the ERP of RV and/or the maintenance of VF as an electrophysiological substrate of high risk patients. Higher DF of VF can be one of predictive values to discriminate the high risk Brugada patients.