Abstract 14112: Outcomes of Subcutaneous Implantable Cardioverter-Defibrillator Procedures in Obese versus Non-Obese Patients: A Retrospective Cohort Study

Abstract

Introduction: Obesity has been proposed as a risk factor for failed subcutaneous implantable cardioverter-defibrillator (S-ICD) shocks due to increased impedance associated with subcutaneous fat. Optimal implant technique, consisting of limiting subcutaneous fat underneath the coil and generator as well as posterior positioning of the generator, may overcome this barrier to successful conversion of ventricular fibrillation (VF) in obese patients. Hypothesis: Optimal S-ICD implant technique can result in successful defibrillation testing regardless of body mass index (BMI). Methods: Consecutive patients who underwent S-ICD placement and defibrillation testing at Rush University Medical Center between 2015-2021 were included. Defibrillation testing consisted of a 65 J shock after closure of the deep layer of the incision. Baseline demographics, procedural data, and chest radiographs were examined. A PRAETORIAN score was calculated based on distance between the coil and sternum, pulse generator to ribs, and posterior generator position. A PRAETORIAN < 90 has been associated with low risk of conversion failure in prior studies. The primary endpoint was the rate of successful first conversion of VF in obese versus non-obese patients. Results: The study included 35 patients. Mean age was 44 ± 13 years, 60% were male, and 51.4% were obese (BMI ≥ 30). Mean PRAETORIAN scores for obese and non-obese patients were 84.7 ± 65.8 and 49.3 ± 31.3, respectively (p=0.067). There were 7 obese and 1 non-obese patients with a score ≥ 90 (p=0.041). Mean shock impedance was 69.3 ± 22.2 Ω and 60.9 ± 20.7 Ω, respectively (p=0.259). There were 3 (16.7%) failed initial shocks in obese patients, and 0 failed initial shocks in non-obese patients (p=0.23). All three obese patients with failed initial shocks had scores ≥ 90 (90, 150, 225). A second 65 J defibrillation test was successful in each of these cases with shock polarity reversal. Conclusions: In this single center study, a PRAETORIAN score < 90 was associated with successful initial conversion from ventricular fibrillation in all obese and non-obese patients. The findings suggest that using optimal technique, a successful implant can be achieved regardless of BMI. Additional multi-center data collection is ongoing.