Outcome of patients with nonischemic dilated cardiomyopathy and unexplained syncope treated with an implantable defibrillator

OBJECTIVES The purpose of this study was to determine the outcome of patients with nonischemic dilated cardiomyopathy, unexplained syncope and a negative electrophysiology test who are treated with an implantable defibrillator. BACKGROUND Patients with nonischemic cardio myopathy and unexplained syncope may be at high risk for sudden cardiac death, and they are sometimes treated with an implantable defibrillator. METHODS This study prospectively determined the outcome of 14 consecutive patients who had a nonischemic cardiomyopathy, unexplained syncope and a negative electrophysiology test and who underwent defibrillator implantation (Syncope Group). Nineteen consecutive patients with a nonischemic cardiomyopathy and a cardiac arrest who were treated with a defibrillator (Arrest Group) served as a control group. RESULTS Seven of 14 patients (50%) in the Syncope Group received appropriate shocks for ventricular arrhythmias during a mean follow-up of 24 +/- 13 months, compared with 8 of 19 patients (42%) in the Arrest Group during a mean follow-up of 45 +/- 40 months (p = 0.1). The mean duration from device implantation until the first appropriate shock was 32 +/- 7 months (95% confidence interval [CI], 18 to 45 months) in the Syncope Group compared to 72 +/- 12 months (95% CI, 48 to 96 months) in the Arrest Group (p = 0.1). Among patients who received appropriate shocks, the mean time from defibrillator implantation to the first appropriate shock was 10 +/- 14 months in the Syncope Group, compared with 48 +/- 47 months in the Arrest Group (p = 0.06). Recurrent syncope was always associated with ventricular tachyarrhythmias. CONCLUSIONS The high incidence of appropriate defibrillator shocks and the association of recurrent syncope with ventricular arrhythmias support the treatment of patients with nonischemic unexplained syncope and a negative electrophysiology test with an implantable defibrillator (C) 1999 by the American College of Cardiology.