Defibrillation testing of the subcutaneous implantable cardioverter-defibrillator at the time of generator replacement

Defibrillation testing (DFT) of the subcutaneous implantable cardioverter-defibrillator (S-ICD) is recommended at the time of implantation,1 but data during generator replacement are lacking.2-4 We prospectively studied all patients undergoing S-ICD generator replacement at the Hospital of the University of Pennsylvania from September 2020 to February 2023. The study was approved by the institutional review board and all patients provided written informed consent. Under general anesthesia, QRS-synchronized 10 J shock impedance with the old and new generators were recorded. DFT was then performed with induction of ventricular fibrillation followed by a 65 J shock. System revision was left to operator discretion.