Cardiovascular Implantable Electronic Devices -> Tachycardia Devices: -> Clinical Trials D-PO06 - Poster Session VI (ID 26) Poster

D-PO06-027 - The Defibrillation Threshold In Patients Undergoing Subcutaneous Implantable Cardioverter-defibrillator Replacement (ID 1345)

 W. Van Der Stuijt: Nothing relevant to disclose.


Background: The extracardiac position of the subcutaneous implantable cardioverter (S-ICD) results in a higher defibrillation threshold (DFT) compared to the transvenous ICD. Implanters can decrease the DFT of S-ICD patients by implanting the device in an optimal position, as demonstrated in de novo implants. However, a recent study described a high proportion of patients with DFT failure after S-ICD generator replacement in patients with a successful DFT during implant.
Objective: This study sought to find the DFT in patients undergoing S-ICD generator replacement.
Methods: This prospective study enrolled patients who underwent S-ICD generator replacement and consecutive defibrillation testing. A binary search defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that terminated the ventricular arrhythmia. Device positioning was assessed by the PRAETORIAN score.
Results: A total of 15 patients were enrolled (age 44 ± 16 years, LVEF 54 ± 7%, BMI 26.1 ± 3.9 kg/m2). All patients had a PRAETORIAN score of ≤ 60, assuring good device positioning. Median DFT was 30J (IQR 20-50) and median impedance 75Ω (IQR 66-94), as shown in Table 1. Out of the 15 patients, 14 (93%) had a successful defibrillation test at a shock output ≤ 50J. One patient showed a DFT of 65J, possibly related to his hypertrophic cardiomyopathy. There was no significant difference between patients with a BMI ≤ 25 kg/m2 and BMI > 25 kg/m2 (p = 0.58).
Conclusion: These results show that the DFT in S-ICD replacements is comparable to the DFT in de novo implants when implanted optimally. This study emphasizes the importance of optimal device positioning of the S-ICD to ensure device functionality.