Skipping Defibrillation Testing at S-ICD Implant Is Safe When Guided by PRAETORIAN Score
A 965-patient RCT shows omitting defibrillation testing during subcutaneous ICD implantation is non-inferior to routine testing when device position is scored by chest X-ray.
Summary
Subcutaneous implantable cardioverter-defibrillators (S-ICDs) protect against sudden cardiac death, but confirming they work requires a defibrillation test — essentially inducing cardiac arrest in the operating room, which carries real risks. The PRAETORIAN-DFT trial randomized 965 patients across 37 centers to either receive or skip this test, using a chest X-ray scoring tool called the PRAETORIAN score to verify device positioning in the no-test group. After nearly three and a half years of follow-up, patients who skipped testing had a slightly lower rate of failed first shocks (1.7% vs. 2.3%) and avoided the 1.7% complication rate tied to the test itself. The findings suggest that for appropriately positioned S-ICDs, routine defibrillation testing can be safely omitted, simplifying the procedure without compromising patient safety.
Detailed Summary
Sudden cardiac death remains one of the leading causes of cardiovascular mortality, and subcutaneous implantable cardioverter-defibrillators (S-ICDs) are a key tool for high-risk patients who do not require pacing. Unlike traditional transvenous ICDs, S-ICDs avoid leads inside the heart, reducing infection risk — but optimal device positioning is critical for effective shock delivery. Historically, surgeons have confirmed this by performing a defibrillation test at implant, deliberately inducing ventricular fibrillation to verify the device can terminate it. This test, however, carries its own serious risks including hemodynamic compromise and death.
The PRAETORIAN-DFT trial asked a straightforward clinical question: can a validated chest X-ray scoring tool — the PRAETORIAN score — replace routine defibrillation testing by predicting whether device positioning is adequate? The multinational randomized trial enrolled 965 patients across 37 centers, assigning them to either standard defibrillation testing or no testing guided by the PRAETORIAN score before hospital discharge.
After a median follow-up of 41 months, the primary endpoint — failed first shock for spontaneous ventricular arrhythmia — occurred in 1.7% of the no-test group versus 2.3% in the tested group, a difference of -0.6 percentage points (95% CI -2.6 to 1.4), meeting the pre-specified non-inferiority margin of 3%. All-cause mortality and arrhythmic death were statistically similar between groups. Critically, 1.7% of patients in the defibrillation testing group experienced potential testing-related complications, a risk entirely avoided in the no-test group. Rates of postoperative device revision were identical.
For clinicians, these results support a meaningful practice change: PRAETORIAN score-guided implantation without routine defibrillation testing is non-inferior in efficacy and reduces procedural risk. This could simplify S-ICD implantation workflows and improve patient safety.
Caveats include that this summary is based on the abstract only, the trial was funded by Boston Scientific (device manufacturer), and generalizability depends on centers' ability to accurately apply the PRAETORIAN scoring system.
Key Findings
- Failed first shock occurred in 1.7% (no test) vs. 2.3% (tested), meeting non-inferiority with a 3% margin.
- Skipping defibrillation testing eliminated a 1.7% procedural complication rate seen in the testing group.
- All-cause mortality and arrhythmic death were statistically equivalent between groups over 41 months.
- Postoperative S-ICD revisions due to poor positioning were identical (n=2 each), confirming PRAETORIAN score reliability.
- PRAETORIAN score-guided implantation can safely replace routine defibrillation testing in S-ICD patients.
Methodology
Multinational randomized controlled trial across 37 centers enrolling 965 S-ICD patients, randomized to defibrillation testing or no testing guided by the PRAETORIAN chest X-ray score. Primary endpoint was failed first shock for spontaneous ventricular arrhythmia, tested for non-inferiority with a 3% absolute risk margin over a median 41-month follow-up.
Study Limitations
This summary is based on the abstract only, as the full text was not accessible, limiting assessment of subgroup analyses and protocol details. The trial was industry-funded by Boston Scientific, introducing potential sponsorship bias. Applicability depends on accurate PRAETORIAN score assessment, which requires training and standardized chest X-ray interpretation.
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