B-po03-050 validation of a modified praetorian score in patients undergoing subcutaneous defibrillator implantation

The PRAETORIAN score (PS) is a 4-step non-invasive tool developed to predict successful defibrillation in patients undergoing subcutaneous defibrillator (S-ICD) implantation, but it has not been validated in a modern, unselected cohort of patients. PS can be difficult to calculate in cases where the S-ICD coil has an irregular course superficial to the sternum. This may lead to discrepancies in PS calculation. Provide a consistent, objective way to calculate the number of coil widths between the S-ICD coil and the sternum. We devised a modified PS where the length of the S-ICD coil was divided into thirds. The distance to the sternum for all thirds was then averaged. The remaining 3 steps in the PS were not changed. The modified PS was assessed in patients undergoing de-novo S-ICD implantation who underwent conversion testing for ventricular fibrillation (CTVF). CTVF success was defined as successful termination of VF with an initial 65J shock. Sensitivity, specificity and positive and negative predictive values were calculated. A modified PS ≥ 150 was considered high risk of CTVF failure. From March 2010 to May 2020, 233 patients underwent de-novo S-ICD implantation. CTVF was performed in 175 (75%). Mean age = 52±16 years, 149 males, mean EF = 28% (24-33), 66% primary prevention, 43% non-ischemic cardiomyopathy. CTVF success in 168 (96%). Sensitivity, specificity, positive and negative predictive values for the modified PS were 57%, 80%, 11% and 98% respectively. In a modern cohort of patients undergoing S-ICD implantation, the modified PS has high negative predictive value meaning a low modified PS score was associated with CTVF success.