Ventricular tachycardia oversensing in S-ICD patients: Case-based brief review.

A 76-year-old woman with permanent atrial fibrillation and a mechanical aortic valve came to our attention. Echocardiography showed a 50-55% ejection fraction (EF) with good prosthesis performance. For symptomatic bradyarrhythmia, she received a VVI pacemaker (Proponent MRI L2010 model; Boston Scientific.). During follow-up, frequent symptomatic (presyncopal) episodes of nonsustained episodes of ventricular tachycardia (VT) were detected. Amiodarone proved unsuccessful; she was then offered an upgrade to an implantable cardioverter defibrillator (ICD) and a subcutaneous ICD (S-ICD) was chosen by the patient. A few weeks later, two sustained VT were detected and effectively treated with 80-J shock delivery. In both cases, device interrogation revealed a VT rate around 163 bpm (370 ms cycle length), below the lowest device detection cutoff. The report is a case-based review.