Study Design and Population
This is a retrospective study of all patients ≥ 18 years old who underwent S-ICD implantation between 2010 and 2022 in a single multihospital healthcare system (Northwestern Medicine, Chicago, IL). Northwestern Medicine is comprised of four tertiary or quaternary care hospitals within a single metropolitan area. All hospitals share a single electronic medical record. Patients who were referred for S-ICD extraction but underwent S-ICD implantation at another institution were excluded from the analysis to ensure that the study population underwent implantation according to a standardized protocol and were followed internally for electrophysiologic care. Patient demographics, clinical characteristics and procedural information were retrospectively abstracted from the electronic medical record for all S-ICD implantation procedures. The primary endpoint of this study was S-ICD removal or extraction, collectively referred to as extraction. If a patient underwent extraction, further clinical information was collected in a retrospective manner from the time of extraction. This study was approved by the Northwestern University Institutional Review Board.