Preoperative Prediction of Shock Impedance for Subcutaneous Implantable Cardioverter Defibrillator Using Chest Computed Tomography

BACKGROUND: High shock impedance is associated with conversion failure among patients with subcutaneous implantable cardioverter defibrillators (S-ICD). Currently, there is no preoperative assessment method for predicting high shock impedance. This study examined the efficacy of chest computed tomography (CT) as a preoperative evaluation tool to assess the shock impedance of S-ICDs. METHODS AND RESULTS: ), who underwent intraoperative conversion tests by inducing ventricular fibrillation, which was terminated with a 65-J shock. A sufficient concordance correlation coefficient was observed between the shock impedance and the amount of adipose tissue (r=0.616, P<0.01) and anteroposterior diameter (r=0.645, P<0.01). In multiple regression analysis, the amount of adipose tissue (β=0.439, P=0.009) and anteroposterior diameter (β=0.344, P=0.038) were identified as independent predictive factors of shock impedance. CONCLUSIONS: The preoperative CT-measured amount of adipose tissue and basal heart anteroposterior diameter are independent predictors of shock impedance. These parameters may be more accurate in identifying higher shock impedance in patients with S-ICDs.