Electrophysiologic characteristics and implications of induced ventricular fibrillation in symptomatic patients with Brugada syndrome.

OBJECTIVES: The study examined the electrocardiographic and electrophysiologic characteristics in relation to programmed ventricular stimulation (PVS)-induced ventricular fibrillation (VF), as well as the implications of PVS-induced VF on the recurrence of cardiac events in symptomatic Brugada syndrome.
BACKGROUND: Brugada syndrome is characterized by ST-segment elevation in the right precordial leads (V(1)-V(3)) and an episode of VF.
METHODS: Thirty-four symptomatic patients with Brugada syndrome (33 men and 1 woman; 44 +/- 12 years old) were classified into two groups according to the inducibility of VF with PVS: 22 patients with induced VF requiring direct cardioversion for termination (Induced VF group) and 12 patients without induced VF (Noninduced VF group).
RESULTS: The induced VF group showed a longer QRS duration, a higher incidence of right bundle branch block and late potentials detected on the signal-averaged electrocardiogram, longer His-ventricular intervals and a longer conduction time from the RVOT to the left ventricle at extrastimulation than those in the non-induced VF group. However, there was no significant difference in the recurrence of cardiac events (VF documented by an implantable cardioverter-defibrillator and sudden cardiac death) between the two groups (8 [36%] of 22 patients vs. 7 [58%] of 12 patients) during long-term follow-up (range 1 to 149 months; mean 38).
CONCLUSIONS: Our data suggest that induction of VF by PVS depends on the severity of depolarization abnormalities but does not predict the recurrence of cardiac events in symptomatic Brugada syndrome, indicating that both depolarization and repolarization abnormalities are important in the development of VF.