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Subcutaneous Defibrillator Implantation With or Without Defibrillation Test: The Primary Results of the Randomized PRAETORIAN-DFT Trial
Reinoud E. KnopsChristelle MarquiéPeter NordbeckRoland TilzLeonard A DijkshoornAnne‐Floor B.E. QuastTom F. BrouwerPier D. LambiaseChristopher CassidyL V A BoersmaMartin C. BurkeTim R BettsVincent ProbstHarish ManyamFrank A.L. E. BrackeHendrik BonnemeierJürgen KuschykGregory GolovchinerAnouk de WegerMarc A. MillerJonas S.S.G. de JongAbdul GhaniNigel LewisE MarijonNick R. BijsterveldP DefayeClaire MartinDuncan C. FieldJan EldersNaushad A. ShaikSerge BovedaWilleke van der StuijtJolien A. de VeldKirsten M. KooimanShari PepplinkhuizenLukas KaiserAnita AryaRaymond TukkieLéon J. P. M. van WoerkensMargriet W. Feenema‐AardemaMichael GliksonA H MaassAmir ZaidiArthur A.M. WildeLouise R.A. Olde NordkampLonneke SmedingMikhael F. El‐Chami
Key result
PRAETORIAN score-guided omission of defibrillation testing is non-inferior to routine testing for failed first shocks.
- Absolute difference -0.6%
- 95% CI -2.6 to 1.4
- P<0.001
- n=965
Figures
Why the study?
Defibrillation testing during subcutaneous ICD implantation is recommended but carries serious risks, and whether omission guided by the PRAETORIAN score is non-inferior for first-shock efficacy was unknown.
Does PRAETORIAN score-guided omission of defibrillation testing prevent failed first shocks for spontaneous ventricular arrhythmias compared to routine defibrillation testing in patients undergoing S-ICD implantation?
Key Points
- This trial aims to determine whether omitting defibrillation testing based on the PRAETORIAN score is non-inferior for first-shock efficacy in S-ICD patients.
- Multinational trial with 965 S-ICD patients from 37 centers, randomized to defibrillation testing or no testing.
- Primary endpoint was failed first shock for spontaneous ventricular arrhythmias, assessed for non-inferiority with a 3% margin.
- Follow-up duration averaged 41 months.
- Failed first shock for spontaneous ventricular arrhythmia was 1.7% in the No-DF testing group compared to 2.3% in the DF testing group (–0.6%, 95% CI [–2.6 to 1.4]; p<0.001).
- No significant differences in all-cause mortality (HR 0.9 [95% CI 0.6–1.4]) or arrhythmic death (HR 0.4 [95% CI 0.04–3.4]).
- 1.7% complications related to DF testing occurred in the DF testing group, with similar S-ICD revisions in both groups (2 each).
Study Design
Type
RCT (n=965)
Multicenter
Yes
Structured PICO
Does PRAETORIAN score-guided omission of defibrillation testing prevent failed first shocks for spontaneous ventricular arrhythmias compared to routine defibrillation testing in patients undergoing S-ICD implantation?
P
Population
965 patients undergoing subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation
I
Intervention
Omission of defibrillation (DF) testing guided by the PRAETORIAN score evaluated before discharge
C
Comparator
Routine defibrillation (DF) testing
O
Outcome
Failed first shock for spontaneous ventricular arrhythmias (tested for non-inferiority with a 3% absolute risk margin)surrogate
Main Result
Effect estimate: Absolute difference -0.6% (95% CI -2.6 to 1.4)
Absolute Event Rate: 1.7% vs 2.3%
p-value: p=<0.001
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Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“The risk-benefit ratio of routinely performing DT seems to favor not doing routine testing.”
Implication
Omission of defibrillation testing guided by the PRAETORIAN score is non-inferior to routine testing for first-shock efficacy in S-ICD patients, while avoiding testing-related complications.
Abstract
Background: To improve survival in patients at risk of sudden cardiac death, subcutaneous ICDs (S-ICDs) require optimal implant positioning for effective shocks. Defibrillation (DF) testing is recommended but carries serious risks. The PRAETORIAN score predicts defibrillation outcomes based on chest X-rays. The PRAETORIAN-DFT trial evaluated whether omission of DF testing guided by the PRAETORIAN score is non-inferior for first-shock efficacy. Methods: In this multinational trial, S-ICD patients from 37 centers were randomized to DF testing or no DF testing. In the No-DF testing group, the PRAETORIAN score was evaluated before discharge. The primary endpoint was failed first shock for spontaneous ventricular arrhythmias, as a surrogate for defibrillation success, tested for non-inferiority with a 3% absolute risk margin. Secondary endpoints included mortality, potential DF testing-related complications, and S-ICD revisions. Results: The included 965 patients (No-DF testing, n=483;DF testing, n=482) were followed for a median of 41 months. Failed first shock for spontaneous ventricular arrhythmia occurred in 1.7% of the No-DF testing group versus 2.3% of the DF testing group (–0.6%, 95% CI [ –2.6 to 1.4]; p<0.001). There were no significant differences in all-cause mortality (HR 0.9 [95% CI 0.6–1.4]) or arrhythmic death (HR 0.4 [95% CI 0.04–3.4]). Potential DF testing-related complications occurred in 1.7% in the DF testing group. Postoperative S-ICD revisions due to inadequate positioning were identical between groups (n=2 each). Conclusions: PRAETORIAN score–guided omission of DF testing- after S-ICD implantation did not increase the risk of failed first shocks for spontaneous ventricular arrhythmias and reduced procedural risk without increasing S-ICD revisions. (Funded by Boston Scientific; PRAETORIAN-DFT).
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Cite This Study
Knops et al. (2026) conducted an RCT in S-ICD patients at risk of sudden cardiac death (n=965). No defibrillation (DF) testing guided by the PRAETORIAN score vs. Defibrillation (DF) testing was evaluated on failed first shock for spontaneous ventricular arrhythmias (Absolute difference -0.6%, 95% CI -2.6 to 1.4, p=<0.001). PRAETORIAN score-guided omission of defibrillation testing was non-inferior to testing for failed first shocks (1.7% vs 2.3%; absolute difference -0.6%, 95% CI -2.6 to 1.4; p<0.001).