Abstract 1831: Different Characteristics Between Spontaneous and Induced Ventricular Fibrillation in Patients with Brugada Syndrome
In patients with Brugada syndrome, ventricular fibrillation (VF) inducibility has been proposed as a strong risk stratifying factor. However, recent studies suggested that VF inducibility was not predictive of future events, particularly in asymptomatic patients. In this study, we assessed the hypothesis that the spontaneous episodes of VF (Spont-VF) could have different characteristics compared with the induced VF (Ind-VF) in Brugada syndrome.
Methods: Twenty male patients with Brugada syndrome who had the type I ST elevation and underwent implantable cardioverter defibrillator (ICD) were enrolled. Twelve episodes of Spont-VF and 24 Ind-VF in 14 symptomatic patients, and 10 Ind-VF in 6 asymptomatic patients were analyzed by means of ICD stored data. The mean and coefficient of variation (CV) of the VF cycle length (VFCL), and mean successive difference (MSD) of VFCL were calculated using intracardiac electrogram during initial 8–10 seconds of VF. QTc dispersion (QTc-d) of a 12-lead ECG was also measured on the same day of VF episodes.
Results: The mean VFCL was not different among Spont-VF and Ind-VF in symptomatic patients, and Ind-VF in asymptomatic patients. The CV and MSD of Spont-VF in symptomatic patients were significantly greater than those of Ind-VF in both symptomatic and asymptomatic groups. QTc-d was significantly greater on the same day of Spont-VF in symptomatic patients compared with those on the same day of Ind-VF in both symptomatic and asymptomatic groups. Both CV and MSD of VFCL were positively correlated with QTc-d (r=0.719, p<0.001 and r=0.713, p<0.001).
Conclusions: In symptomatic patients with Brugada syndrome, cycle length variability was increased during spontaneous episodes of VF compared with that of induced VF. This could be related to the increased heterogeneity of the ventricular refractoriness at the spontaneous episode of VF.