Longitudinal Outcomes After Implantation Of A Subcutaneous Or Transvenous Implantable Cardioverter Defibrillator In Older Patients: A Report From The National Cardiovascular Data Registry

Introduction: The subcutaneous (S-) implantable cardioverter defibrillator (ICD) is an alternative to the transvenous (TV-) ICD that is increasingly implanted in younger patients. However, data on the safety and effectiveness of the S-ICD in older patients are lacking. Methods: We compared S-ICD and single chamber TV-ICD implants in Medicare beneficiaries (≥65yrs) using National Cardiovascular Data Registry ICD Registry data from 9/28/2012 through 12/31/2017. We excluded patients with prior pacemaker or ICD, an indication for pacing or resynchronization, and those undergoing implant in an acute setting. Mortality status was determined using the Medicare master summary beneficiary file. Cox regression analyses with overlap weights were used to compare all-cause mortality. Mean cumulative counts of all-cause readmissions were compared among for Fee for Service beneficiaries. Results: A total of 23,717 patients met inclusion criteria [mean age 72.7±5.8 years, 29% female, 69% ischemic heart disease, 33% atrial arrhythmias, 49% NYHA II, 31.7% NYHA III, ejection fraction (EF) 28±9%, 3% dialysis dependent, 20% with prior ventricular tachycardia]. Compared to TV-ICD patients (n=22,264), S-ICD patients (n=1,453, 6% overall) were more often male, black, diabetic, dialysis dependent and were less likely to have atrial or ventricular arrhythmias or ischemic heart disease. There was no difference in age or EF between the 2 groups. In adjusted analyses, during a median follow-up of 2.3 years (IQR: 1.2 - 3.5), there was no difference between the 2 groups in all-cause mortality (HR 1.04, CI 0.91-1.17, Figure A ) or readmissions (based on overlap of confidence intervals, Figure B ). Conclusions: In a large representative cohort of older patients undergoing ICD implant, all-cause mortality and readmission were similar among S-ICD and TV-ICD recipients. These findings support use of the S-ICD for the prevention of sudden cardiac death in appropriately selected older patients.