Introduction: The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to a transvenous ICD in patients who meet criteria for ICD implantation without concurrent need for cardiac pacing. The objective of this study is to examine the rates of and indications for S-ICD removal and extraction. Methods: A retrospective analysis of all patients who underwent S-ICD implantation between 2010 and 2022 at a single multihospital healthcare system was performed. The primary endpoint was S-ICD removal or extraction. Patient and device characteristics were abstracted from the electronic medical record. Univariate and multivariate analyses were completed to determine factors associated with S-ICD extraction. Results: A total of 372 patients (69.5% male; 48.6 ± 14.4 years old) underwent S-ICD implantation during the study period. There were 22 (5.9%) patients (81.8% male; 52.1 ± 13.2 years old) who underwent S-ICD extraction over a median follow up period of 4.4 [2.0-6.5] years. The median length of time between implantation and extraction was 39.6 [8.3-64.6] months. The most common indications for S-ICD extraction were need for bradycardia pacing (incidence, 1.08%), infection (1.34%), and inappropriate shocks due to oversensing (1.34%). A smoking history and higher body mass index were independently associated with S-ICD extraction. Conclusions: The overall rate of S-ICD extraction over 4.4 [2.0-6.5] years was 5.9%, with the most common indications for extraction being need for bradycardia pacing, infection, and inappropriate shocks due to oversensing. A smoking history and high body mass index are associated with increased rates of S-ICD extraction. With appropriate patient selection for the S-ICD, the need to remove the device after implantation is low.

Atrial fibrillation (AF) is the most common atrial arrhythmia and is subcategorized into numerous clinical phenotypes. Given its heterogeneity, investigations into the genetic mechanisms underlying AF have been pursued in recent decades, with predominant analyses focusing on early onset or lone AF. Linkage analyses, genome wide association studies (GWAS), and single gene analyses have led to the identification of rare and common genetic variants associated with AF risk. Significant overlap with genetic variants implicated in dilated cardiomyopathy syndromes, including truncating variants of the sarcomere protein titin, have been identified through these analyses, in addition to other genes associated with cardiac structure and function. Despite this, widespread utilization of genetic testing in AF remains hindered by the unclear impact of genetic risk identification on clinical outcomes and the high prevalence of variants of unknown significance (VUS). However, genetic testing is a reasonable option for patients with early onset AF and in those with significant family history of arrhythmia. While many knowledge gaps remain, emerging data support genotyping to inform selection of AF therapeutics. In this review we highlight the current understanding of the complex genetic basis of AF and explore the overlap of AF with inherited cardiomyopathy syndromes. We propose a set of criteria for clinical genetic testing in AF patients and outline future steps for the integration of genetics into AF care.