CRO-INSIGHT: Utilization of Implantable Cardioverter Defibrillators in Non-ischemic and Ischemic Cardiomyopathy in a Single Croatian Tertiary Hospital Centre

Background: Implantable cardioverter defibrillators (ICDs) have significantly reduced the incidence of sudden cardiac death in patients with heart failure, particularly those with ischemic heart disease. However, the impact on overall mortality remains controversial, especially in non-ischemic heart failure patients. The Danish Study to Assess the Efficacy of ICDs in Patients with Non-Ischemic Systolic Heart Failure (DANISH) trial and subsequent studies have questioned the efficacy of ICDs in this population, particularly among older patients. The present study aimed to evaluate survival outcomes and predictors in a Croatian cohort of patients with an ICD or cardiac resynchronization therapy defibrillator (CRT-D) device. Methods: This retrospective cohort study analyzed data from 614 patients who received an ICD or CRT-D device at KBC Zagreb between 2009 and 2018. Patient data, including demographic information, device indication, and clinical parameters, were collected at the time of implantation. Follow-up data were systematically recorded to assess device activation and survival outcomes. Statistical analyses included a detailed descriptive analysis, Kaplan-Meier survival estimates, and Cox regression models. Results: The cohort consisted predominantly of males (83.4%), with a mean age of 58.7 years. Most had reduced left ventricular ejection fraction (mean 31.4%) and were classified as New York Heart Association (NYHA) class II or III. Over a median follow-up of 48.4 months, 36.6% of patients died. Device activation occurred in 30.3% of patients, with appropriate activation observed in 88.2% of these cases. Cox regression identified age, non-sustained ventricular tachycardia (NSVT), and decompensation history as significant survival predictors. Conclusions: This study confirmed that appropriate device activation improved survival in patients with an ICD/CRT-D. Age, NSVT, and history of decompensation were key predictors of device activation and survival outcomes. These findings underscore the need for individualized patient assessment when considering inserting ICDs, particularly in non-ischemic heart failure patients. Further research is needed to refine clinical guidelines and optimize patient selection for ICD therapy.