Clinical significance of syncope in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial

Background: Syncope may portend risk of death, but which patients with syncope are at high risk remains unclear. Objective: The ESVEM trial, a multicenter randomized prospective trial, provided the opportunity to compare mortality rates of patients enrolled with syncope to those enrolled with spontaneous ventricular arrhythmias. Methods: Patients enrolled in the ESVEM trial presenting with syncope alone (25 patients) or in combination with ventricular tachycardia (24 patients) were compared with patients with spontaneous ventricular tachycardia alone (332 patients) or ventricular fibrillation (105 patients). All patients had ventricular tachyarrhythmias induced at electrophysiology testing of ≥10 premature ventricular complexes per hour on Holter monitor. Results: Of all patients randomly assigned, arrhythmic death and total mortality rates were the same for those with syncope alone, with ventricular tachycardia and syncope, with ventricular tachycardia alone, or with ventricular fibrillation. At 1 year, arrhythmic and total mortality rate for all patients was 21% and 24%, respectively; for patients with syncope alone, 30% and 29%, respectively (P = NS). At 4 years, arrhythmic death and total mortality rate for all patients was 33% and 42%, respectively; for patients with syncope alone, 37% and 42%, respectively (P = NS). Conclusion: Syncope, associated with induced ventricular tachyarrhythmias at electrophysiologic testing, indicates high risk for death, similar to that of patients with documented spontaneous ventricular tachyarrhythmias.