Subcutaneous implantable cardioverter defibrillator implantation. An analysis of Italian clinical practice and its evolution

Background: The subcutaneous implantable cardioverter defibrillator (S-ICD) is a relatively novel alternative to the transvenous ICD for the treatment of life-threatening ventricular arrhythmias, and is currently used in the clinical practice of several centers. The aim of this analysis was to describe current Italian practice regarding S-ICD implantation and its evolution over the years. Methods: We analyzed 607 consecutive patients (78% male, 48 ± 16 years) who underwent S-ICD implantation in 39 Italian centers from 2013 to 2017. Results: Structural cardiomyopathy was present in 78% of patients and 30% of patients received their device for secondary prevention. The proportion of patients with dilated cardiomyopathy and with left ventricular ejection fraction ≤35% increased from ≤2014 to 2017 (from 38% to 58%, from 33% to 53%, respectively; both p < 0.05). Almost all procedures (97%) were performed in electrophysiology laboratories. Over the last 4 years, the 2-incision implantation technique has been widely adopted, with sub- or inter-muscular positioning of the generator, under local anesthesia or deep sedation (≤2014 versus 2017: all p < 0.001). Defibrillation testing was performed in 81% of patients. Shock energy of ≤65 J was successful in 93.9% of patients and the overall cardioversion success rate at ≤80 J was 99.8%. Conclusions: Our analysis confirmed that the S-ICD continues to be preferentially used in specific patients (younger, less frequently with dilated cardiomyopathy and low ejection fraction.). Nonetheless, we noted a trend toward the wider use of S-ICD in patients with dilated cardiomyopathy and systolic dysfunction over the years. Novel approaches have been adopted while the acute efficacy of the system has remained stably high.