Mortality and readmission in non-ischemic compared with ischemic cardiomyopathies after implantable cardioverter-defibrillator implantation

Abstract

Abstract Background/Introduction Uncertainty remains regarding the benefit of primary prevention ICDs overall in contemporary practice, and particularly in those with NICM compared with ICM. Purpose To evaluate the contemporary risk of death and readmission following following implantable cardioverter-defibrillator (ICD) implantation in patients with non-ischemic cardiomyopathies (NICM) compared with ischemic cardiomyopathies (ICM) in a large nationally representative cohort in the United States. Methods We used data from the American College of Cardiology (ACC) National Cardiovascular Data Registry (NCDR) ICD Registry linked with Medicare claims from April 1, 2010 to December 31, 2013 to establish a cohort of NICM and ICM patients with a left ventricular ejection fraction ≤35% who received a de novo, primary prevention ICD. We compared mortality, all-cause readmission, and heart failure readmission using Kaplan-Meier curves and Cox proportional hazard regressions models. We also evaluated temporal trends in mortality. Results Among 31,044 NICM and 68,458 ICM patients with a median follow up of 2.4 years, one-year mortality was significantly higher in ICM patients (12.3%) compared with NICM (7.9%, p<0.001). The higher mortality in ICM patients remained significant after adjustment for covariates (hazard ratio (HR) 1.40; 95% confidence interval (CI) 1.36 to 1.45), and was consistent in subgroup analyses. These findings were consistent across the duration of the study. ICM patients were also significantly more likely to be readmitted for all causes (adjusted HR 1.15, CI 1.12 to 1.18) and for heart failure (adjusted HR 1.25, CI 1.21 to 1.31). Conclusions The risks of mortality and hospital readmission after primary prevention ICD implantation were significantly higher in patients with ICM compared with NICM, and these findings were consistent across all patient subgroups tested and over the duration of the study. Funding Acknowledgement Type of funding source: None