Arrhythmias & electrophysiology
The Predictive Value of Impedance for Defibrillation Success After S-ICD Implantation: A Reliable Indicator?
Authors' conclusion
Impedance <90 ohms predicts DFT success with a NPV of 98% but misses 50% of DFT failures and is therefore an insufficient surrogate for DFT. Impedance might serve as an intraoperative tool to estimate correct implant position, but this should always be confirmed with imaging to ensure effective shock delivery. (A Randomised Trial of S-ICD Implantation With and Without Defibrillation Testing [PRAETORIAN-DFT]; NCT03495297).
Study context
- Population
- Patients undergoing subcutaneous implantable cardioverter-defibrillator implantationrandomized, 457 underwent defibrillation testing (DFT) according to protocol
- Participants
- 965 patients
- Comparison
- Predictive values of impedance and the PRAETORIAN score for DFT success, using a cutoff of 90 for both values
- Successful DFTn = 445
- Failed DFTn = 12
Methodological detailsmulticenter
- Multicenter
Primary result
As reported in the abstract
Impedance
Failed DFT
87
median · IQR 63–108
Successful DFT
68
median · IQR 57–78
P = 0.014
Further findings
Impedance <90 ohms for predicting successful DFT
- NPV
- 98%
- Sensitivity (one-half of failed DFTs had impedance ≥90 ohms)
- 50%
PRAETORIAN score <90 for predicting successful DFT
- NPV
- 99%
- Sensitivity
- 70%
- Higher positive likelihood ratio and lower negative likelihood ratio than impedance
Original publication
The Predictive Value of Impedance for Defibrillation Success After S-ICD Implantation: A Reliable Indicator? JACC Clin Electrophysiol. Published 11 June 2026. doi:10.
Summarised from the published abstract; every number is checked against it