Outcomes of subcutaneous implantable cardioverter defibrillators: UK tertiary centre experience

Abstract

Abstract Introduction Subcutaneous implantable cardioverter–defibrillators (S-ICDs) were introduced to address limitations associated with the transvenous ICDs (TVICDs). The programming features of the S-ICDs is however restricted compared to TVICDs. Our investigation aims to assess the outcomes of S-ICDs that have been implanted at our institution. Purpose To assess the outcomes of S-ICDs implanted at a tertiary healthcare centre in the United Kingdom. Methods A retrospective analysis was conducted, encompassing data from all individuals who underwent S-ICD implantation at our institution between January 2011 to April 2023 (n=240). Complications were categorized as device-related complications or inappropriate shock (IAS). All occurrences of IAS; lead revisions; infection; pocket hematoma requiring drainage, blood transfusion, or prolongation of hospitalization; and other complications prompting medical or surgical intervention were documented. The underlying causes and outcomes of IAS were reviewed. If S-ICD was either deactivated or explanted, the reasons for such actions were documented. Results Among the 240 patients included in the study, the average age is 46 years, with 66% being male. The average body mass index (BMI) is 27.8 and the ejection fraction (EF) is 43.3%. Comprehensive baseline characteristics are outlined in Table 1. Defibrillation testing (DFT) is a standard practice in our institution to ensure the integrity of S-ICDs and was conducted in all patients unless contraindicated. The success rate of DFT among attempted patients was 73%. The cumulative incidence of device-related complications over the study period was 15%. Eleven patients (4.6%) experienced IAS with T-wave oversensing as the leading cause. Patients undergoing S-ICD implantation for secondary prevention were found to be more susceptible to experiencing IAS (8 Vs 3, p=0.005) but no other baseline characteristics exhibited an association with any complications. The administration of beta-blockers and device reprogramming prevented further IAS in five patients. The remaining patients necessitated interventions such as lead revision, ablation therapy, switching to TVICD, or upgrading to cardiac resynchronisation therapy (CRT). A total of 38 patients required device explant or deactivation. The primary cause for such actions was due to patient mortality. The other notable causes included S-ICD infection, premature battery depletion, and IAS (Table 2). Conclusion Based on our findings, S-ICD emerges as a useful option for the prevention of sudden cardiac death in many patients. The decision regarding the selection of the appropriate ICD for individual patients warrants comprehensive discussion, encompassing a thorough discussion of advantages and disadvantages with the patients. We anticipate that the data elucidated in this study will be valuable in informing future patient care considerations.Table 1Baseline CharacteristicsTable 2Reasons