Diagnostic value of programmed ventricular stimulation in patients with bifascicular block: prospective study of patients with and without syncope

Objectives. The aim of this study was to examine the inducibility of ventricular arrhythmias in patients with bifascicular block both with and without history of syncope and to relate the findings to clinical events during follow-up. Background. Patients with bifascicular block have an increased risk of sudden death that is not reduced by pacemaker treatment. This risk could be related to high incidence of ventricular arrhythmias. Method. Programmed ventricular stimulation was performed in 101 patients with bifascicular block; 41 had history of unexplained syncope, and 60 were asymptomatic. Results. Programmed ventricular stimulation resulted in sustained ventricular arrhythmi in 18 patients (18%), 8 in the syncope group and 10 in the nonsyncope group (p = NS). Three patients in each group had an inducible sustained monomorphic ventricular tachycardia. During mean follow-up of 21 months, 10 patients experienced clinical event defined as sudden death (n = 4), syncope (n = 5) or appropriate discharges from an implantable cardioverter-defibrillator (n = 1). Only one of these patients had an inducible ventricular arrhythmi at baseline. Conclusions. The inducibility of ventricular arrhythmias is high in patients with bifascicular block and of the same magnitude in patients with and without history of syncope. Clinical events during follow-up were not predicted by programmed ventricular stimulation in either of the two groups. The finding of inducible ventricular arrhythmi in patients with bifascicular block should therefore be interpreted with caution.