Exploring S-ICD Extraction rates and frequency in modern PracticeMoied M. Al Sakan MD, Marwan M. Refaat, MDDivision of Cardiology, Department of Internal Medicine, American University of Beirut Medical Center, Beirut, LebanonRunning Title: S-ICD ExtractionWords: 620 (excluding the title page and references)Keywords: subcutaneous, Implantable cardioverter-defibrillator, cardiac arrhythmias, cardiology, cardiovascular diseases, extractionFunding: NoneDisclosures: NoneCorresponding Author:Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FRCPTenured Professor of MedicineTenured Professor of Biochemistry and Molecular GeneticsMember, Division of Cardiology/ Section of Cardiac ElectrophysiologyDirector, Cardiovascular Fellowship ProgramAmerican University of Beirut Faculty of Medicine and Medical CenterPO Box 11-0236, Riad El-Solh 1107 2020- Beirut, LebanonUS Address: 3 Dag Hammarskjold Plaza, 8th Floor, New York, NY 10017, USAOffice: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct)The subcutaneous implantable cardioverter defibrillator (S-ICD) represents a significant advancement in the management of patients at risk for lethal arrhythmias and sudden cardiac death, particularly those not expected to have a need for pacing. This technology offers a compelling alternative to traditional transvenous ICDs (TV-ICDs), especially in young patients with a long-life expectancy, normal heart, and no need for pacing or cardiac resynchronization therapy, at increased risk of infections and with limited vascular access.[1] This study by Arati Gangadharan et al in the Journal of Cardiovascular Electrophysiology sheds light on an important aspect of S-ICD management, which is the extraction rates and indications for S-ICD extraction.[2]In this retrospective analysis of 372 patients undergoing S-ICD implantation between 2010 and 2022, the authors reported an extraction rate of 5.9% over a median follow-up period of 4.4 years. This figure falls within a spectrum of previously reported extraction rates, highlighting a notable variability across studies. What was notable is the importance of smoking and obesity as independent associations with increased S-ICD extraction. This study focused primarily on key indications of S-ICD extraction such as the need for bradycardia pacing, inappropriate shocks due to oversensing, infection and cardiac transplantation. Additional non-infectious indications have been reported such as lead rupture (2.42%), sensing issues (4.35%) and patient discomfort (2.42%). [1] When comparing the indications for lead extraction between this study and the indications noted in the systematic review on S-ICD lead extraction by Riccardo Vio et al, spanning the same period (articles collected until 2022), we can note similarities between the two studies (inappropriate shocks, infection, and the need for cardiac resynchronization therapy) but also other indications included defibrillation threshold testing failure (2.42%), lead malposition (1.93%), and premature battery depletion (0.48%). [1] Cardiac implantable electronic devices has been shown to be of benefit in patients with severe cardiomyopathy. [3,4] Also, when looking at the indications for S-ICD implantation- one of the most common indications for S-ICD implantation was primary prevention in patients with heart failure with reduced ejection fraction, Univariate analysis demonstrated that a history of lower left ventricular ejection fraction (P=<0.001), was associated with S-ICD extraction. (2,5) Notably, this study shed some light on the independent associations with a history of smoking and elevated body mass index (BMI) which serve as important factors that clinicians should consider during the pre-implantation assessment. These findings corroborate existing sparse literature suggesting that obesity and smoking may complicate device function and patient outcomes (2,5-7).The observational design from a single center limit the generalizability of these results to other populations. Future studies incorporating larger, multicenter cohorts also considering the socioeconomic status could provide more definitive insights.[2]In conclusion, while the S-ICD is generally preferred over TV-ICD in appropriately selected patients, the findings from this study highlight the necessity for meticulous pre-implantation assessments and the recognition of specific risk factors that may influence the risk of device extraction. As electrophysiology advances, combining the subcutaneous ICD (S-ICD) with a leadless pacemaker could shift the S-ICD toward becoming the preferred device choice, particularly for patients who would benefit from both defibrillation and pacing functions.[8] Furthermore, as suggested by the authors, the development of S-ICD technology and evolving guidelines over the last ten years may have affected the clinical decision-making process regarding device extraction and implantation as well as the rates of complications.[9]In summary, the results of this study emphasize the need for thorough pre-implantation evaluations and the identification of particular risk factors that may affect the risk of device extraction, even if the S-ICD is typically preferred over the TV-ICD in some patients.[2] The growing use of S-ICDs in a variety of patient populations necessitates continuous assessment of their safety and efficacy, especially when new technologies and indications are developed.