Abstract
Background: Implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with defibrillator (CRT-D) are established efficient therapies, but negative effects of their shocks have been reported. Purpose: We assessed if ICD shock or anti-tachycardia pacing (ATP) is associated with poor prognosis, and which factor predicts shocks in ICD and CRT-D patients. Subjects and Methods: A total of 161 consecutive patients who received ICD (n=132) or CRT-D (n=29) (age 57.2±14.3 years, 78% male, 76% non-ischemic cardiomyopathy (NICM)) were retrospectively analyzed. Results: During the follow-up period of 27.0±20.2 months, cardiac events occurred in 14 patients (1 sudden death, 2 death or 11 hospitalization for heart failure). Patients who experienced at least 1 ICD shock had significantly higher incidence of cardiac events and hazard risk was 1.92 (p<0.05). Such an effect on the prognosis was not observed for ATP. Multivariate analysis indicates that class I anti-arrhythmic agents and non-use of amiodarone were independent predictor of appropriate shock and that of inappropriate shock, respectively. Conclusion: ICD shock, but not ATP, was associated with increase in cardiac events in a group which mainly consists of NICM. Untoward effect of class I anti-arrhythmic agents and benefit of amiodarone on ICD shock incidence need to be considered.
