Focus Issue: DevicesClinicalThe need for a subsequent transvenous system in patients implanted with subcutaneous implantable cardioverter-defibrillator
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,
References (30)
- et al.
Long-term clinical outcomes of subcutaneous versus transvenous implantable defibrillator therapy
J Am Coll Cardiol
(2016) - et al.
Subcutaneous versus transvenous implantable defibrillator therapy: a meta-analysis of case-control studies
JACC Clin Electrophysiol
(2017) - et al.
Subcutaneous versus transvenous implantable defibrillator: an updated meta-analysis
Heart Rhythm
(2021) - et al.
Subcutaneous implantable cardioverter-defibrillator lead extraction
JACC Clin Electrophysiol
(2020) - et al.
Device-related infection in de novo transvenous implantable cardioverter-defibrillator Medicare patients
Heart Rhythm
(2021) - et al.
Long term complications in patients implanted with subcutaneous implantable defibrillators: real-world data from the Extended ELISIR experience
Heart Rhythm
(2021) - et al.
Safety and efficacy of the totally subcutaneous implantable defibrillator
J Am Coll Cardiol
(2015) - et al.
Low inappropriate shock rates in patients with single- and dual/triple-chamber implantable cardioverter-defibrillators using a novel suite of detection algorithms: PainFree SST trial primary results
Heart Rhythm
(2015) - et al.
Reduced risk for inappropriate implantable cardioverter-defibrillator shocks with dual-chamber therapy compared with single-chamber therapy
JACC Heart Fail
(2014) - et al.
Subcutaneous implantable cardioverter defibrillator and defibrillation testing: a propensity-matched pilot study
Heart Rhythm
(2021)
A novel tool to evaluate the implant position and predict defibrillation success of the subcutaneous implantable cardioverter-defibrillator: the PRAETORIAN score
Heart Rhythm
Long-term outcomes of implantable cardioverter-defibrillator therapy in the SCD-HeFT
J Am Coll Cardiol
Implantable cardioverter defibrillators and chronic kidney disease
Curr Probl Cardiol
An entirely subcutaneous implantable cardioverter–defibrillator
N Engl J Med
Subcutaneous or transvenous defibrillator therapy
N Engl J Med
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.
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Dr Mauro Biffi and Dr Giovanni B. Forleo share senior co-authorship.