Subcutaneous and single-chamber transvenous defibrillators: a nationwide matched control study
Authors: Bodin A , Bisson A , Pierre B , Herbert J , Clementy N , Babuty D , Fauchier L 
Published: May 2021

Abstract

Funding Acknowledgements
Type of funding sources: None.
Introduction / Background
Subcutaneous implantable cardioverter–defibrillators (S-ICD) was designed to avoid complications of single-chamber transvenous implantable cardioverter-defibrillators (VVI ICD) by using an entirely extra-thoracic placement.

Purpose
Our objective was to compare outcomes following first VVI ICD or S-ICD implantation in an exhaustive nationwide matched cohort.

Methods
This French longitudinal cohort study was based on the national hospitalization database covering hospital care from for the entire population. All adults (age ≥18 years) hospitalized in French hospitals From January 1, 2010 to September 1, 2020, who underwent a VVI ICD or S-ICD implantation were included. Patients with a previous pacemaker or ICD or with a history of infective endocarditis were excluded. Multivariable analyses for clinical outcomes during the whole follow-up in the groups of interests were performed using a Cox model with all baseline characteristics and reporting hazard ratio. Owing to the non-randomized nature of the study, and considering for significant differences in baseline characteristics, propensity-score matching was also used to control for potential confounders of the treatment outcome relationship.

Results
21,667 patients were included in the cohort, 19,493 patients had a transvenous VVI ICD and 2,174 had a subcutaneous ICD. Mean age was 61.2 ± 13.2 years in the VVI ICD group and 52.3 ± 17.5 years in the S-ICD goup. Coronary artery disease was present in 71.6% of patients with a VVI ICD and 48.2% of patients with a S-ICD. Mean follow-up was 28.8 ± 31.8 months. S-ICD patients had a significant higher rate of all-cause death (HR: 1.684, 95%CI: 1.309-2.165, p &lt; 0.001). There were no significant differences in cardiovascular death (HR: 1.092, 95%CI: 0.697-1.711, p = 0.70) and infective endocarditis (HR: 0.354, 95%CI: 0.067-1.433, p = 0.15) between the two groups
Using propensity score, 1,582 patients with VVI ICD were matched 1:1 with S-ICD patients. Mean follow-up was 4.5 ± 7.2 months. In the matched analysis, there were no significant differences in all-cause death (HR: 1.090, 95%CI: 0.728-1.633, p = 0.68) and cardiovascular death (HR: 1.167, 95%CI: 0.603-2.260, p = 0.65) between the two groups. A trend toward a lower risk of infective endocarditis in the S-ICD group was also observed without reaching significance (HR : 0.219, 95%CI: 0.047-1.017, p = 0.053). A sensitivity analysis in patients with coronary artery disease in the matched cohort was performed. Same trends were observed without significant differences in all-cause death and cardiovascular death.

Conclusion
Our nationwide study highlighted a higher risk of all-cause death in patients treated with subcutaneous which however was not statistically significant after propensity score matching. No differences regarding cardiovascular mortality was found. An interesting trend toward diminution of infective endocarditis was also observed without reaching significancy.