Elsevier

Heart Rhythm

Volume 19, Issue 12, December 2022, Pages 1958-1964
Heart Rhythm

Focus Issue: Devices
Clinical
The need for a subsequent transvenous system in patients implanted with subcutaneous implantable cardioverter-defibrillator

https://doi.org/10.1016/j.hrthm.2022.06.030Get rights and content

Background

The absence of pacing capabilities may reduce the appeal of subcutaneous implantable cardioverter-defibrillator (S-ICD) devices for patients at risk for conduction disorders or with antitachycardia pacing (ATP)/cardiac resynchronization (CRT) requirements. Reports of rates of S-ICD to transvenous implantable cardioverter-defibrillator (TV-ICD) system switch in real-world scenarios are limited.

Objective

The purpose of this study was to investigate the need for a subsequent transvenous (TV) device in patients implanted with an S-ICD and its predictors.

Methods

All patients implanted with an S-ICD were enrolled from the multicenter, real-world iSUSI (International SUbcutaneouS Implantable cardioverter defibrillator) Registry. The need for a TV device and its clinical reason, and appropriate and inappropriate device therapies were assessed. Logistic regression with Firth penalization was used to assess the association between baseline and procedural characteristics and the overall need for a subsequent TV device.

Results

A total of 1509 patients were enrolled (age 50.8 ± 15.8 years; 76.9% male; 32.0% ischemic; left ventricular ejection fraction 38% [30%–60%]). Over 26.5 [13.4–42.9] months, 155 (10.3%) and 144 (9.3%) patients experienced appropriate and inappropriate device therapies, respectively. Forty-one patients (2.7%) required a TV device (13 bradycardia; 10 need for CRT; 10 inappropriate shocks). Body mass index (BMI) >30 kg/m2 and chronic kidney disease (CKD) were associated with need for a TV device (odds ratio [OR] 2.57 [1.37–4.81], P = .003; and OR 2.67 [1.29–5.54], P = .008, respectively).

Conclusion

A low rate (2.7%) of conversion from S-ICD to a TV device was observed at follow-up, with need for antibradycardia pacing, ATP, or CRT being the main reasons. BMI >30 kg/m2 and CKD predicted all-cause need for a TV device.

Introduction

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is currently considered a valid alternative to the transvenous implantable cardioverter-defibrillator (TV-ICD) for the prevention of sudden cardiac death.1, 2, 3 The main advantage of the S-ICD is its extravascular design, which is associated with low rates of surgical, lead, and infective complications that can be managed easily and with a virtually zero mortality in the event of system infection.4, 5, 6, 7, 8 Although representing its most appealing feature, the absence of an endocardial lead burdens the S-ICD system with potential weaknesses. Despite the modern SMART-Pass algorithms, significant rates of inappropriate shocks (IAS) have been reported by several studies, with the lack of a ventricular and atrial endocavitary signal possibly representing an important caveat.9, 10, 11, 12, 13 At the same time, the absence of pacing capabilities severely reduces the appeal of the S-ICD for patients at high risk for developing future conduction disorders or with antitachycardia pacing (ATP) requirements. Finally, although a TV-ICD can be easily upgraded to a cardiac resynchronization therapy (CRT) device in heart failure (HF) patients, the addition of a transvenous (TV) device is instead required in S-ICD recipients.

Adequate patient selection, therefore, is the key to maximize the benefits of the S-ICD system.14 To date, however, reports addressing the rates of S-ICD to TV-ICD switch at long-term follow-up in S-ICD recipients are limited, and no predictors for TV-ICD upgrade have been identified. The aim of this study was to assess the rate of conversion from an S-ICD to a transvenous (TV) device in a large, multicenter, real-world patient cohort implanted with an S-ICD and to identify clinical predictors possibly associated with switching to TV systems.

Section snippets

Methods

The iSUSI (International SUbcutaneouS Implantable cardioverter defibrillator) Registry—former ELISIR project—is a multicenter, open-label, independent, and physician-initiated observational registry, whose composition and characteristics have been previously presented.9,15 This registry was approved by the local institutional review board and the analysis drafted in accordance with the tenets of the Helsinki Declaration.

Baseline characteristics

A total of 1509 patients were enrolled in the study. Mean patient age at S-ICD implant was 50.8 ± 15.8 years, and 76.9% of the patients (n = 1161) were male. Cardiovascular risk factors were not uncommon, with 563 (41.3%) diagnosed with hypertension, 221 (15.5%) with diabetes, and 233 (15.3%) with CKD. The most common underlying arrhythmic substrate was ischemic cardiomyopathy (32.0%), followed by dilatative cardiomyopathy (20.7%) and Brugada syndrome (11.4%). On baseline electrocardiogram

Discussion

This analysis is the first, large, multicenter, cohort study assessing the need for a TV-ICD in real-world S-ICD recipients. The main results from our study can be summarized as follows. (1) In a population of 1509 S-ICD recipients, over median follow-up time of 26.5 months, only 2.7% of patients required a TV device system, resulting in a need for TV rate of 1.1% per patient-year. (2) Median time to TV device implantation was 15.8 months, with high BMI (>30 kg/m2) and CKD being associated with

Conclusion

In a large, real-world cohort of S-ICD recipients, a low overall rate (2.7%; 1.1% per patient-year) of conversion to a TV device was observed at follow-up. Antibradycardia pacing, ATP, or CRT indications were the main reasons for switch to a TV device (63% of patients). A higher BMI (>30 kg/m2) and CKD predict all-cause conversion to a TV device. IHD, older age, and CKD were significantly associated with TV device switching because of the development of pacing/CRT indications at follow-up,

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  • Cited by (0)

    Funding Sources: The authors have no funding sources to disclose.

    Disclosures: Dr Santini is a consultant for Boston Scientific and a member of Boston Scientific Advisory Board. Dr Dello Russo is a consultant for Abbott. Dr Casella has received speaker honoraria from Abbott and Biosense Webster. Dr Kaiser worked as a proctor for Boston Scientific. Dr Tilz is a consultant for Boston Scientific. Dr Tondo serves on the advisory board for Medtronic and Boston Scientific. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

    1

    Dr Alessio Gasperetti and Dr Marco Schiavone share first co-authorship.

    2

    Dr Mauro Biffi and Dr Giovanni B. Forleo share senior co-authorship.

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