Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial

BackgroundThe PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter defibrillator (S-ICD) therapy, using generator and lead positioning on bidirectional chest radiographs. The PRAETORIAN-DFT trial investigates whether PRAETORIAN score calculation is non-inferior to defibrillation testing (DFT), with regard to first shock efficacy in spontaneous events.ObjectiveThis pre-specified sub-analysis assesses the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias.MethodsThis multicenter investigator initiated trial randomized 965 patients between DFT or PRAETORIAN score calculation after de novo S-ICD implant. Successful DFT was defined as conversion of an induced ventricular arrhythmia in less than five seconds from shock delivery, within two attempts. Bidirectional chest radiographs were obtained after implantation. Predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm.ResultsIn total, 482 patients were randomized to undergo DFT. Of these patients, 457 underwent DFT according to protocol, of whom 445 had a successful DFT and 12 had a failed DFT. A PRAETORIAN score ≥ 90 had a positive predictive value of 25% for failed DFT and a PRAETORIAN score < 90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score ≥ 90 was the strongest independent predictor for failed DFT (OR 33.77; CI 6.13-279.95, p<0.001).ConclusionA PRAETORIAN score <90 serves as a reliable indicator for DFT success in S-ICD patients and a PRAETORIAN score ≥90 is a strong predictor for DFT failure.