TY - JOUR
T1 - Defibrillation threshold in elective subcutaneous implantable defibrillator generator replacements
T2 - Time to reduce the size of the pulse generator?
AU - van der Stuijt, W.
AU - Pepplinkhuizen, S.
AU - de Veld, J. A.
AU - Quast, A. B. E.
AU - van Halm, V. P.
AU - Bijsterveld, N. R.
AU - Olde Nordkamp, L. R. A.
AU - Wilde, A. A. M.
AU - Smeding, L.
AU - Knops, R. E.
N1 - Publisher Copyright: © 2023 The Author(s)
PY - 2024/3/1
Y1 - 2024/3/1
N2 - Introduction: The first step-down defibrillation studies in the subcutaneous implantable cardioverter-defibrillator (S-ICD) described a defibrillation threshold (DFT) of 32.5 ± 17.0 J and 36.6 ± 19.8 J. Therefore, the default shock output of the S-ICD was set at 80 J. In de novo implants, the DFT is lower in optimally positioned S-ICDs. However, a retrospective analysis raised concerns about a high DFT in S-ICD replacements, possibly related to fibrosis. Objective: We aimed to find the DFT in patients undergoing S-ICD generator replacement. Methods: This prospective study enrolled patients who underwent S-ICD generator replacement with subsequent defibrillation testing. A pre-specified defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that effectively terminated the induced ventricular arrhythmia. Results: A total of 45 patients were enrolled, 6.0 ± 2.1 years after initial implant. Mean DFT during replacement in the total cohort was 27.4 ± 14.3 J. In patients with a body mass index (BMI) 18.5–25 kg/m2 (N = 22, BMI 22.5 ± 1.6), median DFT was 20 J (IQR 17.5–30). In 18/22 patients, the DFT was ≤30 J and 5/22 patients were successfully defibrillated at 10 J. One patient with hypertrophic cardiomyopathy had a DFT of 65 J. In patients with a BMI >25 kg/m2 (N = 23, BMI 29.5 ± 4.2), median DFT was 30 J (IQR 20–40). In 15/23 patients, the DFT was ≤30 J and 4/23 patients had a successful defibrillation test at 10 J. Conclusions: This study eases concerns about a high DFT after S-ICD generator replacement. The majority of patients had a DFT ≤30 J, regardless of BMI, suggesting that the shock output of the S-ICD could be safely reduced.
AB - Introduction: The first step-down defibrillation studies in the subcutaneous implantable cardioverter-defibrillator (S-ICD) described a defibrillation threshold (DFT) of 32.5 ± 17.0 J and 36.6 ± 19.8 J. Therefore, the default shock output of the S-ICD was set at 80 J. In de novo implants, the DFT is lower in optimally positioned S-ICDs. However, a retrospective analysis raised concerns about a high DFT in S-ICD replacements, possibly related to fibrosis. Objective: We aimed to find the DFT in patients undergoing S-ICD generator replacement. Methods: This prospective study enrolled patients who underwent S-ICD generator replacement with subsequent defibrillation testing. A pre-specified defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that effectively terminated the induced ventricular arrhythmia. Results: A total of 45 patients were enrolled, 6.0 ± 2.1 years after initial implant. Mean DFT during replacement in the total cohort was 27.4 ± 14.3 J. In patients with a body mass index (BMI) 18.5–25 kg/m2 (N = 22, BMI 22.5 ± 1.6), median DFT was 20 J (IQR 17.5–30). In 18/22 patients, the DFT was ≤30 J and 5/22 patients were successfully defibrillated at 10 J. One patient with hypertrophic cardiomyopathy had a DFT of 65 J. In patients with a BMI >25 kg/m2 (N = 23, BMI 29.5 ± 4.2), median DFT was 30 J (IQR 20–40). In 15/23 patients, the DFT was ≤30 J and 4/23 patients had a successful defibrillation test at 10 J. Conclusions: This study eases concerns about a high DFT after S-ICD generator replacement. The majority of patients had a DFT ≤30 J, regardless of BMI, suggesting that the shock output of the S-ICD could be safely reduced.
KW - Defibrillation threshold
KW - Impedance
KW - Pulse generator
KW - Subcutaneous ICD
UR - http://www.scopus.com/inward/record.url?scp=85179829910&partnerID=8YFLogxK
U2 - 10.1016/j.ijcard.2023.131639
DO - 10.1016/j.ijcard.2023.131639
M3 - Article
C2 - 38065323
SN - 0167-5273
VL - 398
JO - International journal of cardiology
JF - International journal of cardiology
M1 - 131639
ER -