Increased mortality and ICD therapies in ischemic versus non-ischemic dilated cardiomyopathy patients with cardiac resynchronization having survived until first device replacement

Abstract

Introduction: Cardiac resynchronization therapy combined with an implantable cardioverter defibrillator (CRT-D) is widely applied in heart failure patients. Sufficient data on arrhythmia and defibrillator therapies during long-term follow-up of more than 4 years are lacking and data on mortality are conflicting. We aimed to characterize the occurrence of ventricular arrhythmia, respective defibrillator therapies and mortality for several years following CRT-D implantation or upgrade.

Material and methods: Eighty-eight patients with ischemic (ICM) or non-ischemic dilated cardiomyopathy (DCM) and at least one CRT-D replacement were included in this study and analyzed for incidence of non-sustained ventricular tachycardia (NSVT), defibrillator shocks, anti-tachycardia pacing (ATP) and mortality.

Results: ICM was the underlying disease in 59%, DCM in 41% of patients. During a mean follow-up of 76.4 ±24.8 months the incidence of appropriate defibrillator therapies (shock or ATP) was 46.6% and was elevated in ICM compared to DCM patients (57.7% vs. 30.6%, respectively; p = 0.017). Kaplan-Meier analysis revealed significantly higher ICD therapy-free survival rates in DCM patients (p = 0.031). Left ventricular ejection fraction, NSVT per year and ICM (vs. DCM) were independent predictors of device intervention. The ICM patients showed increased mortality compared to DCM patients, with cumulative all-cause mortality at 9 years of follow-up of 45.4% and 10.6%, respectively. Chronic renal failure, peripheral artery disease and chronic obstructive pulmonary disease were independent predictors of mortality.

Conclusions: The clinical course of patients with ICM and DCM treated with CRT-D differs significantly during long-term follow-up, with increased mortality and incidence of ICD therapies in ICM patients.

Keywords: cardiac resynchronization therapy; heart failure; implantable cardioverter defibrillator; ischemic cardiomyopathy; non-ischemic dilated cardiomyopathy.

Figure 1

ICD therapy-free survival in ICM and DCM patients. A – Kaplan-Meier estimates for survival free of appropriate shock delivered by CRT-D. B – Kaplan-Meier estimates for survival free of appropriate ATP delivered by CRT-D. C – Kaplan-Meier estimates for survival free of appropriate therapy (shock or ATP) delivered by CRT-D ICM – ischemic cardiomyopathy, DCM – non-ischemic dilated cardiomyopathy, CRT-D – cardiac resynchronization therapy combined with an implantable cardioverter defibrillator (ICD), ATP – anti-tachycardia pacing.

Figure 2

Cumulative survival in ICM and DCM patients. Kaplan-Meier estimates for survival in patients treated with cardiac resynchronization therapy combined with an implantable cardioverter defibrillator (CRT-D) according to disease etiology ICM – ischemic cardiomyopathy, DCM – non-ischemic dilated cardiomyopathy.

Figure 3

ICD therapy-free survival and cumulative survival in patients with CRT-D for primary prevention. A – Kaplan- Meier estimates for survival free of appropriate therapy (shock or anti-tachycardia pacing) delivered by CRT-D. B – Kaplan-Meier estimates for survival in CRT-D patients according to disease etiology ICM – ischemic cardiomyopathy, DCM – non-ischemic dilated cardiomyopathy, CRT-D – cardiac resynchronization therapy combined with an implantable cardioverter defibrillator (ICD).

Figure 4

ICD therapy-free survival in directly implanted versus upgraded CRT-D patients. Kaplan-Meier estimates for survival free of appropriate therapy (shock or anti-tachycardia pacing) delivered by CRT-D in patients with direct implantation of CRT-D or upgrade from previously implanted ICD, pacemaker or CRT-P ICD – implantable cardioverter defibrillator, CRT-D – cardiac resynchronization therapy combined with an ICD, CRT-P – CRT pacemaker.