Intraoperative Application of the PRAETORIAN Score to Predict Optimal Subcutaneous Implantable Cardioverter‐Defibrillator Placement

Background The PRAETORIAN score (PS) estimates the risk of defibrillation failure after subcutaneous implantable cardioverter‐defibrillator (S‐ICD) implantation based on postoperative chest radiography in the standing position. However, the usefulness of assessing the PS in the supine position intraoperatively has not yet been established. Methods We evaluated conventional (standing) and intraoperative supine PS in 124 consecutive Japanese patients undergoing S‐ICD implantation. Changes between conventional and supine PS values were analyzed in two ways: (1) the presence of any difference in the absolute PS values regardless of the risk category, and (2) changes in clinically relevant risk categories for conversion failure (low, intermediate, or high risk). Predictors of discordance between the two assessments were also investigated. Results The median conventional PS was 30; 116 and 8 patients were classified as having low and intermediate risk of conversion failure, respectively. Numerical differences between the conventional and supine PS values were observed in 13 patients. However, clinically meaningful risk reclassification occurred in only two patients, suggesting that intraoperative supine PS assessment may underestimate PRAETORIAN score–based risk classification in a small subset of patients. Among patients with numerical PS changes, supine PS was significantly lower than conventional PS. An elevated BMI was strongly associated with PS discordance. Exploratory receiver operating characteristic curve analysis identified a BMI cutoff of 25.6 kg/m 2 for discriminating patients with numerical PS discordance. Conclusions Intraoperative supine PS assessment shows excellent concordance with conventional standing PS and may provide a practical tool for confirming appropriate system positioning in most Japanese patients.