Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial
Authors: Knops Reinoud E. , van der Stuijt Willeke , Delnoy Peter Paul H.M. , Boersma Lucas V.A. , Kuschyk Juergen , El-Chami Mikhael F. , Bonnemeier Hendrik , Behr Elijah R. , Brouwer Tom F. , Kääb Stefan , Mittal Suneet , Quast Anne-Floor B.E. , Smeding Lonneke , Tijssen Jan G.P. , Bijsterveld Nick R. , Richter Sergio , Brouwer Marc A. , de Groot Joris R. , Kooiman Kirsten M. , Lambiase Pier D. , Neuzil Petr , Vernooy Kevin , Alings Marco , Betts Timothy R. , Bracke Frank A.L.E. , Burke Martin C. , de Jong Jonas S.S.G. , Wright David J. , Jansen Ward P.J. , Whinnet Zachary I. , Nordbeck Peter , Knaut Michael , Philbert Berit T. , van Opstal Jurren M. , Chicos Alexandru B. , Allaart Cornelis P. , Borger van der Burg Alida E. , Clancy Jude F. , Dizon Jose M. , Miller Marc A. , Nemirovsky Dmitry , Surber Ralf , Upadhyay Gaurav A. , Weiss Raul , de Weger Anouk , Wilde Arthur A.M. , Olde Nordkamp Louise R.A. , Alings Marco , Allaart Cornelis P. , Behr Elijah R. , Betts Timothy R. , Bijsterveld Nick R. , Boersma Lucas V.A. , Bonnemeier Hendrik , Borger van der Burg Alida E. , Bracke Frank A.L.E. , Brouwer Marc A. , Brouwer Tom F. , Burke Martin C. , Cheung Jim W. , Chicos Alexandru B. , Clancy Jude F. , Delnoy Peter Paul H.M. , Dizon Jose M. , El-Chami Mikhael F. , Germans Tjeerd , de Groot Joris R. , Jansen Ward P.J. , de Jong Jonas S.S.G. , Kaab Stefan , Knaut Michael , Knops Reinoud E. , Kooiman Kirsten M. , Kuschyk Juergen , Lambiase Pier D. , Leyva Francisco , Miller Marc A. , Mittal Suneet , Nemirovsky Dmitry , Neuzil Petr , Nordbeck Peter , Olde Nordkamp Louise R.A. , van Opstal Jurren M. , Philbert Berit T. , Quast Anne-Floor B.E. , Richter Sergio , Smeding Lonneke , van der Stuijt Willeke , Surber Ralf , Theuns Dominic A.M.J. , Tijssen Jan G.P. , Upadhyay Gaurav A. , Vernooy Kevin , de Weger Anouk , Weiss Raul , Whinnet Zachary I. , Wilde Arthur A.M. , Wright David J. 
Published: November 2021

Background:
The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks.

Methods:
The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population.

Results:

In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%;
P
=0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%;
P
=0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group (
P
=0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group (
P
=0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group (
P
=0.05).

Conclusions:
In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups.

Registration:

URL:
https://www.clinicaltrials.gov
; Unique identifier: NCT01296022.