Noninvasive Impedance Analysis During S-ICD Insertion Provides Justification for Defibrillation Based Testing...

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• Subcutaneous implantable cardioverter-defibrillator (S-ICD) insertion typically includes defibrillation threshold testing (DFT).
• Transvenous ICD (T-ICD) systems do not routinely undergo DFT due to clinical concerns and reliable noninvasive predictors.
• Limited data exists on low voltage (LV) impedance trends and its relation to high voltage (HV) impedance in S-ICD patients.

Purpose of the Study:

• To characterize the trend of LV impedance from S-ICD connection (T0) to final intraprocedural measurement (T4).
• To compare LV impedance with HV impedance during DFT or 10J testing.

Main Methods:

• Analysis of S-ICD implantation data from July 2022 to March 2024.
• Collection of LV impedance during implant and HV impedance during testing (65J DFT or 10J).
• Paired t-tests used to evaluate impedance differences at various time points.

Main Results:

• LV impedance decreased by 18.3% (p <0.001) from T0 to T4 in 53 patients.
• LV impedance at T4 did not significantly differ from HV impedance in 35 patients who underwent testing (p = 0.116).

Conclusions:

• LV impedance predictably declines after S-ICD implantation.
• LV impedance measured 60 minutes post-implant (T4) reliably approximates HV impedance.
• Further evaluation is warranted on how LV impedance influences DFT decisions.