The subcutaneous implantable cardioverter defibrillator in 2019 and beyond.

The completely subcutaneous implantable cardioverter defibrillator (S-ICD) is rapidly evolving to become a complete alternative for the transvenous ICD (TV-ICD) leaving the heart and vasculature untouched. Newer trials and registries in cohorts that are similar to real-world ICD patient populations confirm the initial data on safety and efficacy. Technical improvements have resulted in reduced inappropriate shock rates, although more data are warranted, and new developments such as substernal lead positioning, communication between the S-ICD and a leadless cardiac pacemaker and remote monitoring options have evolved to overcome the shortcomings of S-ICD therapy. With these continuing developments, it is expected that within the next years the S-ICD will continue to evolve to a treatment option for ventricular arrhythmia as effective as the TV-ICD overcoming the shortcomings of transvenous leads as well as the drawbacks of the initial system, providing effective shock therapy, pacing capabilities, low complication and inappropriate therapy rates, and automated remote monitoring.