Perspective:

The S-ICD system has previously been shown to be an effective device in preventing sudden death due to ventricular arrhythmias in patients with cardiac disease. This device has no transvenous or intracardiac components, which eliminates the risk of vascular complications, lung and cardiac perforation, and greatly reduces the risk of severe device/lead-related systemic infection. Patients without sustained ventricular tachycardia, and those who do not require pacing or resynchronization therapy, are good candidates for an S-ICD. Patients are screened to determine whether the electrode (implanted at the left sternal border) is able to adequately sense ventricular arrhythmias, and to minimize the risk of T-wave oversensing (R/T wave amplitude). The latter can result in double counting, leading to inappropriate detection and shocks. Updated sensing algorithms are expected to decrease the incidence of T-wave oversensing and inappropriate therapies. The risk of infection (not systemic infection) is probably higher with an S-ICD as compared to a conventional transvenous device, likely owing to more dissection and a greater number of incisions that are required. Overall, S-ICD devices are preferable in younger patients, given the prospect of multiple anticipated procedures for battery depletion and/or lead failure over time. Greater experience is required in patients with CHD, especially given variant anatomy, and presence of bundle branch block, which may interfere with optimal sensing.