The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a novel technology for the treatment of sudden cardiac death. The system consists of a pulse generator implanted in the left axillary position and a single subcutaneous lead for detection and delivery of therapy. Initial clinical trials of S-ICDs demonstrated improved safety and efficacy when compared to transvenous ICD systems, leading to their widespread approval. The main advantage of the S-ICD is the avoidance of vascular access and the complications associated with transvenous leads. Owing to limitations of S-ICDs, patients who require pacing support or antitachycardia pacing are not candidates for the device; instead, this system is currently used most commonly in young patients with previous lead malfunction, limited vascular access, or low risk for subsequent bradycardia or antitachycardia pacing. Findings from device trials support S-ICDs as a viable alternative to transvenous ICDs in certain patients, and the current limitations associated with S-ICDs are likely to be addressed in future iterations of the device, extending its indications and target patient populations.
