Subcutaneous versus transvenous ICDs: a population-level comparison of incidence, patient characteristics, and complications of S-ICDs, ICDs, and CRT-Ds in a nationwide Dutch cohort (2018-2020)
Authors: Samuel M , Van Der Stoel M , Rienstra M , Maass A 
Published: November 2023

Abstract

Background
Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have emerged as a safe and effective alternative to ICDs for the prevention of sudden cardiac death. Compared to ICDs, S-ICDs aim to reduce morbidities associated with the transvenous lead including lead dislocation and infection. Limited evidence exists for the utilization, patient selection, and complications of S-ICDs in current real-world clinical practice.

Purpose
Our aim was to compare the implantation rate, patient characteristics, and complications of patients who underwent S-ICD, ICD, and CRT-D implants and replacements in the Netherlands from 2018 to 2020.

Methods
The Netherlands Heart Registration includes all adult patients who underwent an ICD implant or replacement at 28 hospitals in the Netherlands (2018-2020). Annual crude, age-, and sex-standardized incidence rates were assessed with Poisson regression models with robust variances. Patient characteristics and complications were compared between ICD types with ANOVA tests. Determinants of complications were identified with multivariable logistic regression models.

Results
Of 17,080 patients who had a de novo ICD implant (n=10,317) or replacement (n=6,763) in the Netherlands (2018-2020), 1408 (8.2%) patients had an S-ICD, 9441 (55.3%) patients received an ICD only, and 6231 (36.5%) patients received a CRT-D. The incidence of de novo S-ICDs were stable over time, however the incidence of de novo ICD only and CRT-D implants decreased by 5% and 11%, respectively (p&lt;0.05 for both; Figure 1). Patients who received S-ICDs were younger (53 years, IQR 41-62) than ICD (66 years, IQR 57-73) and CRT-D (70 years, IQR 62-75) patients (p&lt;0.05). A greater proportion women had S-ICDs (25.0%) and CRT-Ds (26.7%) implanted compared to ICDs (19.9%) (p&lt;0.05). Further, less atrial fibrillation patients had S-ICDs (21.6% vs ICD 30.9%, and CRT-D 32.4%). ICDs for primary prevention were implanted in 56.4%, 48.4%, and 81.2% of S-ICD, ICD, and CRT-D patients, respectively (p&lt;0.05). The incidence of lead dislocations was less among S-ICD patients compared to ICD and CRT-D patients (p&lt;0.001; Figure 2). There was no difference detected for other complications or long-term mortality (p&gt;0.05 for all; Figure 2). Infections in S-ICD patients [aOR 0.2 (95% CI 0.1-0.9)] and in-hospital bleeding for CRT-D patients [aOR 0.4 (95% CI 0.2-0.9)] decreased among patients who underwent an ICD implant in recent years. In addition, advancing age was identified as a risk factor for in hospital bleeding in S-ICD patients [aOR 1.1 (95% CI 1.0-1.2)] and for pneumothorax in CRT-D patients [aOR 3.6 (95% CI 2.0-6.8)].

Conclusion
In real-world practice, S-ICDs were implanted in younger patients with fewer comorbidities and portended a lower risk of lead dislodgement than ICDs and CRT-Ds; however, the population-level implantation rate of S-ICDs did not vary between 2018 to 2020 in the Netherlands.