Main image of with a Heart surrounded by an EMBLEM and a EMPOWER devices

EMBLEM™ S-ICD PRAETORIAN Trial

Proven Protection. Personalised Care.

Decades of data. Emerging clinical evidence.

PRAETORIAN DFT: Primary endpoint met

The primary objective of the PRAETORIAN DFT trial is to determine whether omitting ventricular fibrillation (VF) conversion testing during S-ICD implantation is non-inferior to performing VF conversion testing, when post operative position of the system is confirmed by assessment of the PRAETORIAN score.28

The trial met the primary endpoint and demonstrated non-inferiority (p = 0.0002) of omitting VF conversion testing in EMBLEM S-ICD implants when guided by the PRAETORIAN score.29,**

There was no difference between the two arms with respect to the cumulative incidence of appropriate shocks (p = 0.22).30 Both arms experienced very low first failed shock conversion of spontaneous arrhythmias.29

Simple diagram for first failed shock conversion from the PRAETORIAN DFT Trial. It shows 1.7% in the no-DFT arm versus 2.3% in the DFT arm.

Complication rates were lower in the no-DFT arm compared to the DFT arm.

  • Within 24 hours, the potentially DFT-related complication rate in the DFT arm was 1.7% compared to zero in the no-DFT arm (difference -1.7%, 95% CI -2.8% to -0.5%).29
  • Within 30 days of S-ICD implant, the composite complication rate was significantly higher in the DFT arm compared to the no-DFT arm (difference -3.1%, 95% CI -5.3% to -0.09%).29
Bar charts comparing potential DFT-related complications within both arms of the trial. Within 24 hours, complication rate in the DFT arm was 1.7% compared to zero in the no-DFT arm. And within 30 days, composite complication rate was 4.8% in the DFT arm compared to 1.7% in the no-DFT arm.

Comparable high first and final shock efficacy of spontaneous arrhythmias in both arms. In the no-DFT arm, first and final shock efficacy was 92.1% and 97.9%, respectively.30 In the DFT arm, first and final shock efficacy was 91.5% and 97.5%, respectively.30

A stacked bar chart showing first and final shock efficacy of spontaneous arrythmias in both arms. No-DFT arm, 92.1% and 97.9% respectively. DFT arm 91.5% and 97.5%.

Trial investigators found that omitting VF conversion testing, when the S-ICD system position is confirmed using the PRAETORIAN score, simplifies the procedure, reduces complications and found no increase in first failed shocks or S-ICD revisions post implant.29,**

Note: In this trial, DFT testing is synonymous with VF conversion testing during implant.

PRAETORIAN DFT: Primary endpoint met

The primary objective of the PRAETORIAN DFT trial is to determine whether omitting ventricular fibrillation (VF) conversion testing during S-ICD implantation is non-inferior to performing VF conversion testing, when post operative position of the system is confirmed by assessment of the PRAETORIAN score.28

The trial met the primary endpoint and demonstrated non-inferiority (p < 0.001) of omitting VF conversion testing in EMBLEM S-ICD implants when guided by the PRAETORIAN score.29,**

Both arms experienced very low first failed shock conversion of spontaneous arrhythmias.29

Simple diagram for first failed shock conversion from the PRAETORIAN DFT Trial. It shows 1.7% in the no-DFT arm versus 2.3% in the DFT arm.

Complication rates were lower in the no-DFT arm compared to the DFT arm.

  • After DFT testing, the potentially DFT-related complication rate in the DFT arm was 1.7% compared to zero in the no-DFT arm (p < 0.01).29
  • Within 30 days of S-ICD implant, the composite complication rate was significantly higher in the DFT arm compared to the no-DFT arm (p < 0.01).29
Bar charts comparing potential DFT-related complications within both arms of the trial. Within 24 hours, complication rate in the DFT arm was 1.7% compared to zero in the no-DFT arm. And within 30 days, composite complication rate was 4.8% in the DFT arm compared to 1.7% in the no-DFT arm.
While numerically lower in the no-DFT arm, there was no statistically significant difference in all-cause mortality and arrhythmic death.29
  No-DFT (n = 483)DFT (n = 482)HR (95% CI)
All-cause mortality35 (7.2%)39 (8.1%)0.9 (0.6-1.4)
Arrhythmic death1 (0.2%)3 (0.6%)0.4 (0.04-3.4) 

Intraoperative repositions were higher in the no-DFT arm compared to the DFT arm and the differences were not statistically significant.29
 No-DFT (n = 483)DFT (n = 482)HR (95% CI)
Intraoperative repositioning23 (4.8%)15 (3.1%)1.55 (0.80-3.08)

 

Trial investigators found that omitting VF conversion testing, when the S-ICD system position is confirmed using the PRAETORIAN score, simplified the procedure, reduced complications and found no increase in first failed shocks or S-ICD revisions post implant.29,**

Note: In this trial, DFT testing is synonymous with VF conversion testing during implant.

The PRAETORIAN DFT trial is sponsored by Academic Medical Center (AMC) in Amsterdam. Funding for the trial is provided by Boston Scientific.

The manufacturer recommended VF conversion testing during EMBLEM S-ICD implant, replacement and concomitant device implants is being evaluated based on the PRAETORIAN DFT trial results and additional available data.

PRAETORIAN XL: Longest randomized trial of ICDs

The PRAETORIAN XL trial reconsented patients for a total follow-up of eight years to evaluate the superiority of the S-ICD to TV-ICD. Patients randomized to the S-ICD arm experienced a 42% lower risk of major complications compared to patients in the TV-ICD arm (HR: 0.58, 95% CI 0.36-0.95, P = 0.03).2

Read Circulation article on PRAETORIAN XL

PRAETORIAN: A smart alternative to TV-ICD

PRAETORIAN is the first prospective, randomized, head-to-head, non-inferiority clinical trial that compares S-ICD to TV-ICD. The trial followed 850 patients at 40 centers across Europe and the United States. Full results were published in 2020.9

Bar chart shows arrow down and 92% reduction in serious lead-related complications.
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ATLAS trial: S-ICD superior to TV-ICD

The ATLAS trial met its primary superiority endpoint demonstrating a highly significant 92% reduction in serious lead-related complications† at six months for the EMBLEM S-ICD compared to any manufacturers' single chamber TV-ICD devices. p = 0.0031

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Package showing components of the Lux-Dx myLUX app for heart patients

UNTOUCHED study: Inappropriate shocks lower than TV-ICD

The UNTOUCHED study evaluated inappropriate shock (IAS) rates from third-generation S-ICD devices among a conventional patient population. Using enhanced discrimination and standard programming, investigators achieved a lower IAS rate than recorded for most TV-ICDs. The IAS free rate achieved at 18 months was 95.9%.8

Circle filled in to 95.9% to designate the inappropriate shock free rate at 18 months.

Continued reduction in IAS rates‡ 

Updates to technology and new implant techniques are credited with a continued reduction of inappropriate shock rates. Recent S-ICD one-year inappropriate shock rates from the UNTOUCHED and RHYTHM DETECT studies were less than 2.0%.18,22 This is five times lower than substernal ICD and comparable to TV-ICD.1,31

Updates to technology and new implant techniques are credited with a continued reduction of inappropriate shock rates. Recent S-ICD one-year inappropriate shock rates from the UNTOUCHED and RHYTHM DETECT studies were less than 2.0%.18,22 This is five times lower than substernal ICD and comparable to TV-ICD.1,30

Bar chart shows arrow down and 92% reduction in serious lead-related complications.

APPRAISE ATP: Importance of shared decision making

The APPRAISE ATP trial demonstrated superiority with a 28% relative risk reduction in time to first all-cause shock for the ATP ON arm compared to the ATP OFF arm (Log-rank P-value = 0.005). This represents an absolute all-cause shock reduction in 1% of PP ICD indicated patients per year.32

The APPRAISE ATP trial demonstrated superiority with a 28% relative risk reduction in time to first all-cause shock for the ATP ON arm compared to the ATP OFF arm (Log-rank P-value = 0.005). This represents an absolute all-cause shock reduction in 1% of PP ICD indicated patients per year.31

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One percent absolute shock reduction per year versus lifetime risk of lead in the heart.

Circulation articles:

Device-related complications in transvenous versus subcutaneous defibrillator therapy during long-term follow-up: The PRAETORIAN-XL Trial

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Subcutaneous Defibrillator Implantation With or Without Defibrillation Test: The Primary Results of the Randomized PRAETORIAN-DFT Trial

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Explore more evidence:

MODULAR ATP
ATLAS

* Caution: Investigational Device. Limited by US law to investigational use only. Not available for sale.

** The manufacturer recommended VF conversion testing during EMBLEM S-ICD implant, replacement, and concomitant device implants is being evaluated based on the PRAETORIAN DFT trial results and additional available data.

† In the ATLAS trial, serious complications were defined as moderate-severe or severe tricuspid regurgitation, hemothorax/pneumothorax, cardiac perforation, tamponade, pericardial effusion or pericarditis, ipsilateral upper extremity deep vein thrombosis and lead dislodgement or loss of sensing or pacing requiring revision.

‡ IAS graph references for S-ICD (see at bottom of Clinical data tab)

IDE study: Weiss R, Knight BP, Gold MR, et al. Safety and efficacy of a totally subcutaneous implantable-cardioverter defibrillator. Circulation. 2013;128(9):944-953. doi:10.1161/circulationaha.113.003042

Effortless Registry: Lambiase PD, Theuns DA, Murgatroyd F, et al. Subcutaneous implantable cardioverter-defibrillators: long-term results of the EFFORTLESS study. Eur Heart J. 2022;43(21):2037-2050. doi:10.1093/eurheartj/ehab921

PRAETORIAN: Knops RE, Olde Nordkamp LRA, Delnoy PHM, et al. Subcutaneous or transvenous defibrillator therapy. N Engl J Med. 2020;383(6):526-536. doi:10.1056/NEJMoa1915932

SMART Pass: Theuns D, Brouwer TF, Jones PW, et al. Prospective blinded evaluation of a novel sensing methodology designed to reduce inappropriate shocks by the subcutaneous implantable cardioverter-defibrillator. Heart Rhythm. 2018;15(10):1515-1522. doi:10.1016/j.hrthm.2018.05.011

UNTOUCHED Gen 3: Gold MR, Lambiase PD, El-Chami MF, et al. Primary results from the Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction (UNTOUCHED) trial. Circulation. 2021;143(1):7-17. doi:10.1161/CIRCULATIONAHA.120.048728

ATLAS S-ICD: Healey JS, Krahn AD, Bashir J, et al. Perioperative safety and early patient and device outcomes among subcutaneous versus transvenous implantable cardioverter defibrillator implantations: a randomized, multicenter trial. Ann Intern Med. 2022;175(12):1658-1665. doi:10.7326/M22-1566

UNTOUCHED SMART Pass: Boersma LVA, Aasbo J, Knops RE, et al. The impact of SMART pass algorithm status on inappropriate shock rates in the UNTOUCHED study. Europace. 2022;24(suppl 1):euac053.391. doi:10.1093/europace/euac053.391

RHYTHM DETECT: Botto GL, Ziacchi M, Nigro G, et al. Intermuscular technique for implantation of the subcutaneous implantable defibrillator: a propensity-matched case–control study. Europace. 2023;25(4):1423-1431. doi:10.1093/europace/euad028

§ Communication testing assessed a pass/fail of communication at the programmed S-ICD telemetry setting and was required at the 6-month visit in four body postures. The test had to pass in more than 88% of attempts, across all postures, to be defined as successful.

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REFERENCES:

  1. Healey JS, Krahn AD, Bashir J, et al. Perioperative safety and early patient and device outcomes among subcutaneous versus transvenous implantable cardioverter-defibrillator implantations: a randomized, multicenter trial. Ann Intern Med. 2022;175(12):1658-1665. doi:10.7326/M221-566.
  2. Olde Nordkamp LRA, de Veld JA, Ghani A, et al. Device-related complications in transvenous versus subcutaneous defibrillator therapy during long-term follow-up: the PRAETORIAN-XL trial. Circulation. 2025;0(0). doi:10.1161/CIRCULATIONAHA.125.074576.
  3. Leong DP, Dokainish H, Mondesert B, et al. Effects of implantable cardioverter-defibrillator leads on the tricuspid valve and right ventricle: a randomized trial. JACC Clin Electrophysiol. 2024;10(9):2088-2096. doi:10.1016/j.jacep.2024.04.034.
  4. Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: executive summary. Circulation. 2018;138(13):e210-e271. doi:10.1161/CIR.0000000000000548.
  5. Russo AM, Desai MY, Do MM, et al. ACC/AHA/ASE/HFSA/HRS/SCAI/SCCT/SCMR 2025 appropriate use criteria for implantable cardioverter-defibrillators, cardiac resynchronization therapy, and pacing. J Am Coll Cardiol. 2025;85(11):1213-1285. doi:10.1016/j.jacc.2024.11.023.
  6. Bardy G, Smith W, Hood M, et al. An entirely subcutaneous implantable cardioverter-defibrillator. N Engl J Med. 2010;363(1):36-44.
  7. Gold MR, El-Chami MF, Burke MC, et al. Postapproval study of a subcutaneous implantable cardioverter-defibrillator system. J Am Coll Cardiol. 2023;82(5):383-397. doi:10.1016/j.jacc.2023.05.034.
  8. Gold MR, Lambiase PD, El-Chami MF, et al. Primary results from the UNTOUCHED trial. Circulation. 2021;143(1):7-17. doi:10.1161/CIRCULATIONAHA.120.048728.
  9. Knops RE, Olde Nordkamp LRA, Delnoy PHM, et al. Subcutaneous or transvenous defibrillator therapy. N Engl J Med. 2020;383(6):526-536. doi:10.1056/NEJMoa1915932.
  10. Knops RE, van der Stuijt W, Delnoy P, et al. Efficacy and safety of appropriate shocks and antitachycardia pacing in transvenous and subcutaneous ICDs: PRAETORIAN analysis. Circulation. 2022;145(5):321-329. doi:10.1161/CIRCULATIONAHA.121.057816.
  11. Lambiase PD, Theuns DA, Murgatroyd F, et al. Long-term results of the EFFORTLESS study. Eur Heart J. 2022;43(21):2037-2050. doi:10.1093/eurheartj/ehab921.
  12. Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J. 2022;43(40):3997-4126. doi:10.1093/eurheartj/ehac262.
  13. Payne JE, Gold MR. A substernal defibrillator lead with pacing capability. JACC Clin Electrophysiol. 2019;5(2):197-198. doi:10.1016/j.jacep.2018.12.006.
  14. Romers H, van Dijk V, Boersma L. Evolution of extravascular ICD therapy. Heart Rhythm O2. 2023;4(1):59-64. doi:10.1016/j.hroo.2022.09.021.
  15. Boston Scientific. CRM Product Performance Report. Q3 2024.
  16. Knops RE, Lloyd MS, Roberts PR, et al. A modular communicative leadless pacing-defibrillator system. N Engl J Med. 2024;391(15):1402-1412. doi:10.1056/NEJMoa2401807.
  17. Lloyd MS, Brisben AJ, Reddy VY, et al. Design and rationale of the MODULAR ATP global clinical trial. Heart Rhythm O2. 2023;4(7):448-456. doi:10.1016/j.hroo.2023.05.004.
  18. Boersma LVA, Aasbo J, Knops RE, et al. SMART Pass algorithm status and inappropriate shocks in UNTOUCHED. Europace. 2022;24(Suppl 1):euac053.39. doi:10.1093/europace/euac053.391.
  19. Boston Scientific. EMBLEM S-ICD and EMBLEM MRI S-ICD User’s Manual. 2021.
  20. van der Stuijt W, Williams JL, Brisben AJ, et al. Battery longevity and its predictors in subcutaneous implantable cardioverter-defibrillators (S-ICDs): A mathematical analysis derived from a large dataset. Heart Rhythm. Mar 2025;22(3):868-870. doi:10.1016/j.hrthm.2024.09.009.​
  21. Akar J, et al. Use of remote monitoring and outcomes in ICD patients. Heart Rhythm Society Scientific Sessions. 2014;Abstract LB03-03.
  22. Botto GL, Ziacchi M, Nigro G, et al. Intermuscular S-ICD implantation: propensity-matched study. Europace. 2023;25(4):1423-1431. doi:10.1093/europace/euad028.
  23. Winter J, Siekiera M, Shin DI, et al. Long-term performance of intermuscular S-ICD implantation. Europace. 2017;19(12):2036-2041. doi:10.1093/europace/euw297.
  24. Brouwer TF, Miller MA, Quast ABE, et al. Evaluation of four S-ICD implantation techniques. Circ Arrhythm Electrophysiol. 2017;10:e004663. doi:10.1161/CIRCEP.116.004663.
  25. Droghetti A, Locatelli A, Casiraghi B, et al. Totally submuscular S-ICD implantation in obese patients. Clin Case Rep. 2016;4(10):1009-1011. doi:10.1002/ccr3.652.
  26. Migliore F, Allocca G, Calzolari V, et al. Intermuscular two-incision S-ICD technique: registry results. Pacing Clin Electrophysiol. 2017;40(3):278-285. doi:10.1111/pace.12987.
  27. Knops RE, Olde Nordkamp LR, de Groot JR, et al. Two-incision S-ICD implantation technique. Heart Rhythm. 2013;10:1240-1243. doi:10.1016/j.hrthm.2013.05.016.
  28. Quast ABE, Baalman SWE, Betts TR, et al. Rationale and design of the PRAETORIAN-DFT trial: A prospective randomized CompArative trial of SubcutanEous ImplanTable CardiOverter-DefibrillatoR ImplANtation with and without DeFibrillation testing. Am Heart J. 2019;214:167-174. doi:10.1016/j.ahj.2019.05.002.
  29. Knops R. A randomized comparison of subcutaneous implantable cardioverter defibrillator implantation with or without defibrillation testing: the primary results of the PRAETORIAN-DFT Trial. HRS 2026. LB-525395.
  30. Friedman P, Murgatroyd F, Boersma LVA, et al. Chronic safety and performance of the EV-ICD: pivotal study. Heart Rhythm. 2023;20(7):1091-1092. doi:10.1016/j.hrthm.2023.04.038.
  31. Schuger C, Joung B, Ando K, et al. APPRAISE ATP randomized clinical trial. JAMA. 2024;332(20):1723-1731. doi:10.1001/jama.2024.16531.
  32. Lloyd MS, Reddy VY, Roberts P, et al. One-year outcomes of the MODULAR ATP trial. Circ Arrhythm Electrophysiol. 2025. doi:10.1161/circep.125.014395.