The PRAETORIAN Trial is an investigator-sponsored study (ISR)* initiated, designed and led by Academic Medical Center in Amsterdam (AMC) and Reinoud E. Knops, MD, PhD. It is the first prospective randomized head-to-head trial comparing the performance of S-ICD and TV-ICD.

The trial hypothesis was that the S-ICD is non-inferior to the TV-ICD with respect to major ICD-related adverse events, including:

  • Inappropriate shocks
  • ICD-related complications that require intervention
  • Lead-related complications

The trial enrolled 849 patients between March 2011 and January 2017 within the EU and US.



Data from the PRAETORIAN trial confirmed that the S-ICD can be the preferred therapy choice over the TV-ICD for protection from sudden cardiac death. The S-ICD offers comparable performance for the majority of ICD-indicated patients who do not have a need for pacing, while avoiding the serious complications associated with TV-ICDs such as serious infections and lead-related complications.

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Primary and Secondary Endpoints**


Mortality Rates

  • No significant difference in overall and arrhythmic mortality rates between the two groups.
  • Mortality rate was low in both groups, even though:
    • Over 90% had ischemic (>68%) or non-ischemic heart failure
    • Secondary prevention for 19% of S-ICD patients and 20% of TV-ICD patients
    • Median EF was 30%
    • Median age was 63 years
  • Arrhythmic deaths were identical in both groups.
  • Numerically, more deaths occurred in the S-ICD group; this difference was due to non-cardiac causes including cancer and gastrointestinal disease.


Lead-Related Complications

  • Data showed a statistical difference in lead-related complications, with TV-ICD patients experiencing more than 4 times as many as S-ICD patients did.1
  • The S-ICD leaves the vasculature untouched, thereby reducing the risk of acute and future complications associated with transvenous leads.
  • Eliminating device leads within the vasculature is particularly important for ICD-indicated patients with co-morbidities such as diabetes and renal disease who often are at an increased risk of infection and may have vascular access issues.2

Infections Requiring Device Extraction

  • Numerically, TV-ICD patients experienced twice as many infections that required device extraction as S-ICD patients did.
  • Data in >91,000 transvenous lead extractions demonstrated that those extracted for infection had significantly higher rates of complications and mortality.3

Device-Related Complications

  • No statistical difference in device-related complications at the median 4-year follow-up.
  • The trial authors have initiated an extended follow-up, PRAETORIAN XL, and anticipate that at 8 years the S-ICD will demonstrate superiority to TV-ICD for all device-related complications.1

Inappropriate Shock Rates

  • No significant difference in inappropriate shock rates between the two groups.
  • The PRAETORIAN trial used mainly devices available prior to 2016. Studies using modern S-ICDs like the EMBLEMTM S-ICD have demonstrated even lower rates of IAS.5

S-ICD: A Smart Alternative to TV-ICD

Because it avoids some of the more major complications associated with the TV-ICD, including serious infection and lead-related complications, data shows that the S-ICD is an appropriate and potentially desirable alternative for primary and secondary ICD-indicated patients who do not require pacing. 

Additional Trial Results9

  • Mean implant time for S-ICD was only 5 minutes more than TV-ICD (55 min vs 50 min implant time).
  • 2-incision technique was utilized in 70% of all S-ICD implants.
  • Appropriate shock rates for the S-ICD group were higher than the TV-ICD group; only one patient with an S-ICD was converted to a CRT-D at two years for slow VT where ATP could potentially benefit.
    • Higher rates in S-ICD group likely due to: (1) devices used prior to 2016 without SMART Pass, (2) conditional programming zone of 180 bpm.4-5***
    • Other contemporary S-ICD studies featured appropriate shock rates of 5.3%4,5 [1 yr.] in patients with a SMART Pass enabled S-ICD (comparable to 6.5% and 5.9% rates for single chamber TV-ICDs in the PainFree SST and ADVANCE III trials6, 10).

Reducing TV-ICD Infections Can Lower Mortality Rates

When it comes to reducing complications, lowering mortality rates and cutting costs, avoiding infected TV-ICD leads can go a long way.

  • Data in >91,000 transvenous lead extractions found that those extracted for infection had a higher overall complication rate and a higher in-hospital mortality rate compared to those without infection.3
  • In this same study, the median cost of lead extraction was $39,308 for infected devices and $14,916 for non-infected devices.

Contemporary S-ICDs Further Reduce Rates of Inappropriate Shock

SMART PassTM, included in the EMBLEM MRI S-ICD, has been shown to reduce IAS rates by 68%.4

  • In the more recent UNTOUCHED study, the 1-year IAS rate was 3.1%,5 which is comparable to or lower than the rates observed with TV-ICDs in other studies, including the PRAETORIAN trial.1, 6-8
  • In addition, the 1-year IAS rate was 2.4% for those who received an EMBLEM MRI with SMART Pass.5, 9

S-ICD Procedures Are Becoming More Common Than Ever

Optimized implant techniques (such the intermuscular technique) and implant best practices have emerged as experience with S-ICD has increased to over 79,000 patients worldwide—and counting.



The PRAETORIAN trial is being extended to an 8-year follow-up, PRAETORIAN XL, that is due to complete in 2023. PRAETORIAN XL will be completed with the primary objective of establishing superiority of S-ICDs to TV-ICDs for acute and chronic complications.