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. 2024 Sep;47(9):1185-1191.
doi: 10.1111/pace.15055. Epub 2024 Aug 5.

A manual synchronous low energy shock impedance as a predictor of successful defibrillation testing during subcutaneous ICD implantation

Naiara Calvo  1   2   3 , Carlos Rubén López-Perales  1   2 , Teresa Olóriz  1   2 , Francisco Díaz-Cortegana  1 , Beatriz Jáuregui  1   2 , Nina Soto  1 , Pilar Rodríguez  1 , Eva Santamaría  1   2 , M Rosario Ortas  1   2 , Antonio Asso  1   2
Affiliations

A manual synchronous low energy shock impedance as a predictor of successful defibrillation testing during subcutaneous ICD implantation

Naiara Calvo et al. Pacing Clin Electrophysiol. 2024 Sep.

Abstract

Background: Guidelines recommend defibrillation testing (DFT) during subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Implant position, patient characteristics and device factors, such as shock impedance, influence defibrillation success. To evaluate the shock impedance, a manual synchronous 10J shock (low energy synchronous shock [LESS]) can be delivered, without the need to induce ventricular fibrillation (VF).

Objective: To compare LESS and DFT impedance values and to evaluate the diagnostic accuracy of LESS impedance for predicting a successful DFT during S-ICD implantation.

Methods: Consecutive S-ICD implantations were included. Shock impedances were compared by paired t-tests. Univariate analysis was performed to investigate factors associated with successful DFT. A prediction model of successful DFT based on LESS impedance was assessed by logistic regression. Receiver operating characteristic (ROC) curve, area under the ROC curve and the Hosmer-Lemeshow tests were used to evaluate the accuracy of LESS impedance.

Results: Sixty patients were included (52 ± 14 years; 69% male). LESS and DFT impedance values were highly correlated (r2 = 0.97, p < .01). Patients with a failed first shock had higher body mass index (BMI) (30 ± 3 vs. 25.7 ± 4.3, p = .014), higher mean LESS (120 ± 35Ω vs. 86. ± 23Ω, p = .0013) and DFT impedance (122 ± 33Ω vs. 87 ± 24Ω, p = .0013). ROC analysis showed that LESS impedance had a good diagnostic performance in predicting a successful conversion test (AUC 84% [95% CI: 0.72-0.92]) with a cutoff value of <94Ω to identify a successful DFT (sensitivity 71%, specificity 73%).

Conclusion: LESS impedance values without the need to induce VF can intraoperatively predict a successful DFT.

Keywords: defibrillation testing; shock impedance; subcutaneous implantable cardioverter defibrillator; ventricular fibrillation.

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References

REFERENCES

    1. Bardy GH, Smith WM, Hood MA, et al. An entirely subcutaneous implantable cardioverter‐defibrillator. N Engl J Med. 2010;363:36‐44.
    1. Weiss R, Knight BP, Gold MR, et al. Safety and efficacy of a totally subcutaneous implantable cardioverter defibrillator. Circulation. 2013;128:944‐953.
    1. US Food and Drug Administration. News & Events. FDA approves first subcutaneous heart defibrillator. Published September 28, 2012. Accessed October 13, 2017. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm321755.htm
    1. Healey JS, Hohnloser SH, Glikson M, et al. Shockless IMPLant Evaluation [SIMPLE] Investigators. Cardioverter defibrillator implantation without induction of ventricular fibrillation: a single‐blind, non‐inferiority, randomised controlled trial (SIMPLE). Lancet. 2015;385:785‐791.
    1. Bänsch D, Bonnemeier H, Brandt J, et al. NORDIC ICD Trial Investigators. Intra‐operative defibrillation testing and clinical shock efficacy in patients with implantable cardiovert‐ er‐defibrillators: the NORDIC ICD randomized clinical trial. Eur Heart J. 2015;36:2500‐2507.

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