Prevention of sudden cardiac death: focus on the subcutaneous implantable cardioverter-defibrillator

The implantable cardioverter-defibrillator (ICD) is the most effective therapy to prevent sudden cardiac death (SCD) in high-risk patients. To overcome infections and failure of transvenous leads, the most frightening complications of conventional ICDs, a completely subcutaneous ICD (S-ICD) has been developed and is currently adopted in routine clinical practice. In view of their long life-expectancy, low competitive risk of dying from non-arrhythmic causes, and high lifetime risk of lead-related complications requiring surgical revisions, young patients with cardiomyopathies and inherited arrhythmia syndromes have traditionally been considered ideal candidates for the S-ICD. However, as growing evidence supported S-ICD safety and efficacy, initial niche implant indications were abandoned in favor of a widespread use of this technology, that is currently adopted in common ICD candidates with severe left ventricular dysfunction. Indeed, guidelines recommend S-ICD implantation as an alternative to TV-ICDs in all ICD candidates, unless pacing is required. This review focuses on the contemporary experience with the S-ICD and explores future scenarios in which device-to-device communication will enable to combine leadless therapies.