Development of the subcutaneous implantable cardioverter-defibrillator for reducing sudden cardiac death

Implantable cardioverter‐defibrillators (ICDs) detect ventricular arrhythmias responsible for causing sudden cardiac arrest and then deliver a high‐voltage defibrillation shock to terminate the arrhythmia and restore normal cardiac function. Conventional transveneous ICD (TV‐ICD) systems require one or more leads to be implanted into the heart through the venous anatomy. While TV‐ICDs are well tolerated by most patients, the invasive approach can be associated with severe complications, including systemic infection, cardiac injuries, and lead failures. An entirely subcutaneous ICD (S‐ICD) system was developed as a less invasive alternative to TV‐ICDs without requiring leads in or on the heart. The S‐ICD system provides therapy with a left lateral pulse generator and parasternal electrode configuration that is placed under the skin outside the rib cage, resulting in a much lower risk profile. Advances in defibrillation research and far‐field sensing combined to enable development of the commercial S‐ICD system. An investigation device exemption (IDE) clinical investigation followed, with FDA approval in September 2012. Evaluation of the long‐term performance of the S‐ICD system continues, with two independent postmarket registries and a prospective randomized head‐to‐head trial versus the transvenous ICD.