Inappropriate shocks by subcutaneous implantable cardioverter-defibrillator due to T-wave oversensing in hyperkalemia leading to ventricular fibrillation

Introduction The implantable cardioverter-defibrillator (ICD) has reduced mortality in survivors of sudden cardiac arrest and patients at high risk of sudden cardiac death. This benefit comes at the cost of device-related complications, including those related to transvenous leads. The subcutaneous ICD (S-ICD) is an alternative to the conventional transvenous ICD (TV-ICD) system and has no transvenous leads, thereby avoiding endocardial lead–related complications. However, with only subcutaneous electrodes, rhythm detection and discrimination is a much more challenging task for the S-ICD. We describe a case of ventricular fibrillation induced by inappropriate shocks from the S-ICD owing to T-wave oversensing (TWOS) in the setting of hyperkalemia and dialysisdependent chronic renal failure.