T wave oversensing in subcutaneous implantable cardioverter defibrillator secondary to hematoma formation: A potential cause of early postimplantation inappropriate shocks

T wave oversensing (TWOS) is the most common cause of inappropriate shocks in subcutaneous cardioverter-defibrillators (S-ICD). We are presenting a patient with severe ischemic cardiomyopathy who received a S-ICD while on antiplatelets therapy. Pressure dressing was applied due to significant bleeding. On the first postoperative day, the device delivered 26 inappropriate shocks after removal of the pressure dressing. Interrogation revealed new TWOS, likely related to changes in the sensing vectors after hematoma formation.