The mortality outcome after implantable cardioverter-defibrillator implantation according to indication for implantation and underlying etiology: a Nationwide Cohort study

Abstract Background and objectives There are few nationwide data about the mortality outcome after implantable cardioverter-defibrillator (ICD) implantation. The aim of this study was to evaluate the mortality outcome after ICD implantation according to indication for implantation (primary vs. secondary prevention) and underlying etiology (non-ischemic vs. ischemic heart disease) with a nationwide cohort data of Korea. Methods During the period from January 1, 2008 to December 31, 2017, 3,558 patients (mean age, 67.7±11.4 years) with newly-implanted ICD who were aged 19 years or older were identified by 50-percents random sampling from the Korean National Health Insurance Service database. Results Patients with primary and secondary prevention ICD were 1,097 (30.8%) and 2,461 (69.2%), respectively. Patients with non-ischemic and ischemic heart disease were 2,487 (69.9%) and 1,071 (30.1%), respectively. Overall all-cause mortality was 20.4% during the follow-up period (mean 24 months). The mortality rates in patients with primary and secondary prevention ICD were 26.2% and 17.9%, respectively. The mortality rates in patients with non-ischemic and ischemic heart disease were 16.1% and 30.4%, respectively. In Kaplan-Meier estimates of survival according to both indication for implantation and underlying etiology, the best prognostic group was patients with secondary prevention ICD and having non-ischemic etiology. The worst prognostic group was patients with primary prevention ICD and having ischemic etiology. The survival probability was below 50% (45.2%) 5 years after ICD implantation in patients with primary prevention ICD and having ischemic etiology. Conclusions In Korean nationwide data, patients with primary prevention ICD and having ischemic etiology show the worst prognosis. About half of these patients died of any cause within five years. Funding Acknowledgement Type of funding source: None