Abstract 13862: Appropriate Therapy in the Subcutaneous and Transvenous ICD: A Secondary Analysis of the PRAETORIAN Trial

Introduction: The randomized PRAETORIAN trial demonstrated non-inferiority of the subcutaneous implantable cardioverter-defibrillator (S-ICD) compared to the transvenous ICD (TV-ICD) with regard to inappropriate shocks and complications. Due to its extrathoracic position, the S-ICD lacks the possibility to provide antitachycardia pacing (ATP) which might result in more appropriate shock therapy. In this pre-specified secondary analysis, we aim to compare first occurrence of appropriate therapy in the S-ICD and TV-ICD. Methods: The PRAETORIAN trial is an international, multicenter, randomized trial (NCT01296022) in which 849 patients with a class I or IIa indication for ICD therapy and without the need for pacing were randomized in a 1:1 ratio to receive either an S-ICD (n = 426) or a TV-ICD (n = 423). Analyses were performed in the modified intention-to-treat population, which included patients according to the group to which they had been randomly assigned regardless of the device they received, but excluded patients who did not receive any ICD. Results: At a median follow-up of 49.1 months, 164 patients received appropriate therapy, of whom 86 in the S-ICD group and 78 in the TV-ICD group (48-month Kaplan-Meier estimated cumulative incidence 19.4% and 17.5%, respectively; hazard ratio 1.12; 95%CI, 0.83 to 1.53; p=0.45). In 83 patients (97%) in the S-ICD group the first arrhythmia was treated with a shock and in 3 patients (3%) with ATP. In 25 patients (32%) in the TV-ICD group the first arrhythmia was treated with a shock, in 31 patients (40%) solely with ATP and in 22 patients (28%) with ATP followed by a shock. Conclusions: In this secondary analysis of the PRAETORIAN trial, we found no statistical difference in first occurrence of appropriate therapy in the S-ICD group and TV-ICD group. Due to ATP, patients were less often treated with shocks in the TV-ICD group. A further analysis of all appropriate therapy in the PRAETORIAN trial could reveal the true benefit of ATP.