Elsevier

International Journal of Cardiology

Volume 323, 15 January 2021, Pages 100-105
International Journal of Cardiology

Comparison of transvenous vs subcutaneous defibrillator therapy in patients with cardiac arrhythmia syndromes and genetic cardiomyopathies

https://doi.org/10.1016/j.ijcard.2020.08.089Get rights and content

Highlights

  • High rates of appropriate shocks were observed in patients with inherited arrythmia syndromes and genetic cardiomyopathies.

  • Appropriate therapies were mainly offset by inappropriate therapies and lead failures in transvenous ICDs.

  • Subcutaneous ICD may help lowering the rate of appropriate and inappropriate shocks and thereby improve patient outcomes.

Abstract

Background

Inherited arrhythmia syndromes and genetic cardiomyopathies attribute in a significant proportion to sudden cardiac death. Implantable cardioverter defibrillators (ICDs) are the cornerstone in the prevention of sudden death in high-risk patients. However, ICD therapy is also associated with high rates of inappropriate shocks and/or device-related complications especially in young patients.

Objective

To determine the outcome of high-risk patients with inherited arrhythmia syndromes and genetic cardiomyopathies comparing two defibrillator technologies.

Method

Between 2010 and 2018, 183 consecutive patients from two large German tertiary care centers were enrolled in the study. The majority of patients (83%) had either cardiac channelopathies or idiopathic ventricular fibrillation without cardiac structural abnormalities, while the remaining 17% had a genetic cardiomyopathy (HCM/ARVC). Eighty-six patients (47%) received a transvenous ICD (TV-ICD), while a subcutaneous ICD (S-ICD) was implanted in another 97 patients (53%).

Results

During a mean follow-up of 4.3 years, 30 patients had an appropriate ICD therapy (annual rate 3.8%). Fifteen patients experienced an inappropriate shock (annual rate 1.9%). Lead failure occurred in 17 (9%) patients and was less frequent in the S-ICD group (OR 0.48, 95%CI 0.38–0.62). Adverse defibrillator events, defined as a composite of inappropriate shocks and lead failure requiring surgical revision were significantly lower in the S-ICD group as compared to the TV-ICD group (OR 0.55, 95%CI 0.41–0.72). There was a non-significant trend towards lower appropriate shocks in the S-ICD group, that in combination with all-cause shocks yielded in a significantly higher freedom of any shock in the S-ICD group (RR 39%, p = 0.003). No deaths occurred during follow-up.

Conclusion

The present data favor the use of the subcutaneous ICD for patients with inherited arrhythmia syndromes and genetic cardiomyopathies who do not need anti-bradycardia pacing.

Introduction

Implantable cardioverter defibrillators (ICDs) are widely used in primary and secondary prevention of sudden cardiac death [1]. Conventional transvenous ICDs (TV-ICDs) rely on leads placed over venous vessels and anchored in the endocardium of the heart. Apart from short-term complications such as pneumothorax or cardiac tamponade, long-term complications may play a far more critical role. Over time, these leads become encapsulated with fibrous tissue, complicating replacement or removal. There is good evidence that transvenous ICD leads lose their long-term functionality in up to 20% and that mechanical lead fractures precipitate inappropriate shocks or even impede delivery of appropriate therapy for ventricular tachyarrhythmias [2,3]. In addition, lead-associated complications significantly increase morbidity and mortality of patients [4,5]. Patients with inherited cardiac arrhythmia syndromes and patients with genetic cardiomyopathies are usually at young age when defibrillator therapy is indicated and mostly have a normal life-expectancy. Together with their often active life-style, this imposes a predicament for ICD therapy.

The subcutaneous ICD (S-ICD) was developed to ameliorate long-term complications related to conventional endocardial leads, such as lead fracture or lead infection [6]. Its advantages are offset by its inability of pacing in terms of anti-tachycardia therapy (ATP) or for anti-bradycardia pacing. Despite the perception that the S-ICD is similarly useful as the TV-ICD, a considerable disparity in the usage of the S-ICD remains and decisions for a specific defibrillator type are often made based on experience and anticipation [7]. Randomized trials that compare the TV-ICD with the S-ICD are lacking and the approval of the S-ICD was based on prospective trials in the absence of control groups [6]. Few case-control and retrospective studies have compared the two in terms of efficacy and complications with limited follow-up data [[8], [9], [10]]. Moreover, data regarding outcomes of patients with arrhythmogenic cardiomyopathies and S-ICD are very limited, with only two systematic analyses addressing this topic [11,12].

The current study aimed to assess the long-term outcome of S-ICD patients compared to TV-ICD patients in a selected cohort of patients with either cardiac arrhythmia syndromes or genetic cardiomyopathies. We hypothesized that S-ICD therapy in these patients will display lower rates of lead-related complications and therefore less adverse events during long-term follow-up compared to the TV-ICD.

Section snippets

Patient selection

Patients with cardiac arrhythmia syndromes or genetic cardiomyopathies implanted with an ICD from 2010 until 2018 at the Hannover Medical School and the University Medical Centre Mannheim were included in the study. Cardiac arrhythmia syndromes were defined as either Brugada syndrome, long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia (CPVT) or idiopathic ventricular fibrillation with onset <45 years of age. Patients with genetic cardiomyopathies had

Patient population

A total of 183 consecutive patients with either cardiac arrhythmia syndromes or genetic cardiomyopathies were implanted at two large German tertiary care centers and were included in this analysis. A cumulative follow-up of 782 patient years was available. Only 3 (2%) patients were lost to follow-up after a median uneventful follow-up of 18 months.

Baseline characteristics are provided in Table 1. The mean age at implantation was 40 ± 15 years, 78 patients (43%) were female. Secondary prevention

Main findings

We report the outcome of a large cohort of patients at high risk for ventricular tachyarrhythmias who were implanted with a transvenous ICD vs subcutaneous ICD for primary or secondary prevention. In this multicenter study we compared the outcome of 86 patients implanted with a TV-ICD to 97 patients who received an S-ICD. The total cohort comprised patients diagnosed with either cardiac arrhythmia syndromes or genetic cardiomyopathies. The main findings of the present study are: 1) appropriate

Conclusion

In comparison with the TV-ICD, the present data favor the use of the S-ICD for patients with inherited arrhythmia syndromes and genetic cardiomyopathies who do not need anti-bradycardia pacing.

Funding

None.

Declaration of competing interest

None declared.

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JK and JML contributed equally

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