Effectiveness of subcutaneous implantable cardioverter-defibrillator testing in patients with hypertrophic cardiomyopathy

doi:10.1016/j.ijcard.2016.12.187

International Journal of Cardiology

Volume 231, 15 March 2017, Pages 115-119

https://doi.org/10.1016/j.ijcard.2016.12.187 Get rights and content

Abstract

Background

Subcutaneous ICD (S-ICD) is a promising option for Hypertrophic Cardiomyopathy (HCM) patients at risk of Sudden Cardiac Death (SCD). However, its effectiveness in terminating ventricular arrhythmias in HCM is yet unresolved.

Methods

Consecutive HCM patients referred for S-ICD implantation were prospectively enrolled. Patients underwent one or two attempts of VF induction by the programmer. Successful conversion was defined as any 65 J shock that terminated VF (not requiring rescue shocks). Clinical and instrumental parameters were analyzed to study predictors of conversion failure.

Results

Fifty HCM patients (34 males, 40 ± 16 years) with a mean BMI of 25.2 ± 4.4 kg/m2 were evaluated. Mean ESC SCD risk of was 6.5 ± 3.9% and maximal LV wall thickness (LVMWT) was 26 ± 6 mm. In 2/50 patients no arrhythmias were inducible, while in 7 (14%) only sustained ventricular tachycardia was induced and cardioverted. In the remaining 41 (82%) patients, 73 VF episodes were induced (1 episode in 14 and > 1 in 27 patients). Of these, 4 (6%) spontaneously converted. In 68/69 (98%) the S-ICD successfully cardioverted, but failed in 1 (2%) patient, who needed rescue defibrillation. This patient was severely obese (BMI 36) and LVMWT of 25 mm. VF was re-induced and successfully converted by the 80 J reversed polarity S-ICD.

Conclusions

Acute DT at 65 J at the implant showed the effectiveness of S-ICD in the recognition and termination of VT/VF in all HCM patients except one. Extreme LVH did not affect the performance of the device, whereas severe obesity was likely responsible for the single 65 J failure.

Introduction

Hypertrophic Cardiomyopathy (HCM) is the most common inherited heart muscle disorder and a leading cause of sudden cardiac death (SCD) in young adults [1], [2]. Patients at high risk of SCD benefit from primary prophylaxis with an implantable cardioverter defibrillator (ICD). However, because of their young mean age at implantation, HCM patients are more likely to suffer device-related complications and up to 4% intravascular lead related complications [3], [4], [5], [6]. The subcutaneous ICD (S-ICD) [7] eliminates the need for lead placement in the heart and is expected to eliminate intravascular lead-related complications and lead malfunctioning at follow up [8], [9].

However, compared with other arrhythmogenic conditions, HCM possesses unique features that might influence the efficacy of the device, such as increased left ventricular (LV) mass and unpredictable electrical substrate [10]. Some clinicians express concerns that the defibrillation threshold (DFT) in HCM may be higher than in other cardiomyopathies, and may increase over time in relation to LV mass and extent of myocardial fibrosis [11]. Furthermore, because of the subcutaneous parasternal placement of the leads, the S-ICD requires greater shock energy compared to transvenous ICDs, in order to convert potentially lethal arrhythmias [3]. This uncertainty is similar to the debate that occurred in the early transvenous ICD days, and threatens to hinder the clinical use of S-ICD in HCM patients, in the absence of convincing evidence supporting its effectiveness in this particular population. Thus, we felt it timely to assess post-implantation DFT testing in a cohort of HCM patients, in order to evaluate S-ICD effectiveness in the detection and termination of induced ventricular fibrillation (VF) and assess potential predictors of failure.

Section snippets

Study population

Consecutive HCM patients referred for S-ICD implantation for both primary and secondary prevention at seven Italian Centers from June 2014 to May 2016 were prospectively enrolled. The diagnosis of HCM was based on ultrasound characteristics: a hypertrophied, non-dilated left ventricle (wall thickness of at least 15 mm) in the absence of another cardiac or systemic disease capable of producing a similar degree of hypertrophy [1]. For all patients, informed consent to participate in the study was

Demographics and clinical profile

We evaluated 50 consecutive HCM patients with a mean age of 40 ± 16 years (Table 1). Fifteen were females (30%), 22 (42%) were < 40 years and 28 (58%) were ≥ 40 years. Mean BMI was 25.2 ± 4.4 kg/m² [18.1–36], with 4 obese (BMI ≥ 30) patients. Eight patients (16%) were in NYHA class > I, mean LV ejection fraction was 62 ± 8% and 8 patients had history of Atrial Fibrillation. Seven (14%) patients had basal Left Ventricular Outflow Tract Obstruction (LVOTO) of at least 30 mm Hg and 1 patient (2%) had a prior

Discussion

The entirely subcutaneous ICD represents an appealing alternative to a transvenous device in HCM patients, who are often young, do not require pacing, and face considerable device-related complications over their lifetime, including those related to lead substitutions and infections [3], [4], [5]. However, a perception persists among some clinicians that the unique features of HCM, such as extreme increase in LV wall thickness and mass and unpredictable electrical substrate, may affect the

Conclusions

Acute defibrillation testing at 65 J at the implant showed the effectiveness of S-ICD in the recognition and termination of VT/VF in all HCM patients except one. Extreme LVH did not affect the performance of the device, whereas severe obesity was likely responsible for the single 65 J direct polarity failure observed in our series. Actually HCM patients, who do not require pacing, or those who are at higher risk for transvenous ICD related complications, may benefit from long-term protection

Conflict of interest

The authors report no relationships that could be construed as a conflict of interest.

Acknowledgments

Dr. I. Olivotto is supported by the Italian Ministry of Health: RF-2013-02356787 (Left ventricular hypertrophy in aortic valve disease and hypertrophic cardiomyopathy: genetic basis, biophysical correlates and viral therapy models), NET-2011-02347173 (Mechanisms and treatment of coronary microvascular dysfunction in patients with genetic or secondary left ventricular hypertrophy) and “Monitoraggio e prevenzione delle morti improvvise cardiache giovanili in Regione Toscana” Acronimo ToRSADE -

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Cited by (24)

Validation of the PRAETORIAN score in a large subcutaneous implantable cardioverter-defibrillator collective: Usefulness in clinical routine
2024, Heart Rhythm
To assess the risk of unsuccessful conversion of ventricular fibrillation during defibrillation testing (DFT) with the subcutaneous implantable cardioverter-defibrillator (S-ICD), the PRAETORIAN score has been proposed.
The purpose of this study was to validate the PRAETORIAN score in a large S-ICD collective.
A retrospective single-center analysis of S-ICD patients receiving intraoperative DFT was performed. DFT was performed using a stepwise protocol with 65-J standard polarity, change of polarity, increase to 80 J, and repositioning if necessary. If all DFTs failed, we switched to a transvenous ICD.
Overall, 398 patients were analyzed (268 male [67.3%]; mean age 42.4 ± 15.9 years; mean body mass index [BMI] 25.9 ± 4.8 kg/m²). Successful DFT with the first ICD shock was observed in 264 patients (66.3%). One hundred fourteen patients were defibrillated with the second (n = 104) or third (n = 10) DFT after changing shock polarity and/or shock energy. Overall, 20 patients needed at least 3 DFT (ie, 80 J and/or re-positioning). The majority (n = 88 [65.7%]) of DFT failures occurred before 2015 with the first-generation S-ICD. PRAETORIAN score was an independent predictor of DFT failure (odds ratio [OR] 1.007; 95% confidence interval [CI] 1.003–1.011 P ≤.001), while whereas BMI alone was not (P = .31). Presence of hypertrophic cardiomyopathy (HCM) (OR 2.6; 95% CI 1.3–4.4; P = .004) was predictive for at least 1 unsuccessful DFT in our multivariate regression analysis.
PRAETORIAN score proved to be a useful and valid predictive tool for successful DFT, whereas BMI only had a limited role. Patients with HCM were at increased risk for DFT failure or needed higher DFT energy.
Subcutaneous Implantable Cardioverter Defibrillators in Pediatrics and Congenital Heart Disease
2023, Cardiac Electrophysiology Clinics
Subcutaneous Implantable Cardioverter-Defibrillators in Pediatrics and Congenital Heart Disease: A Pediatric and Congenital Electrophysiology Society Multicenter Review
2020, JACC: Clinical Electrophysiology
Citation Excerpt :
The etiology of this failure remains unclear as the sensing vector, shock impedance, and repeat defibrillation testing were all unchanged/successful. Several reviews have suggested that, particularly in patients at risk for failed successful defibrillation, the S-ICD has advantages that improve its conversion ability (17–19). These include the ability to deliver larger clinical energy and the generator location in a postero-lateral position with a corresponding shock vector that incorporates more left ventricular mass.
The primary goal of this study was to evaluate the implant experience and midterm results of subcutaneous implantable cardioverter-defibrillators (S-ICDs) in pediatric patients and those with congenital heart disease.
The S-ICD was developed to avoid the lead-related complications associated with transvenous systems. The absence of intravascular or intracardiac components offers potential advantages to pediatric patients and those with congenital heart disease.
This international, multicenter, retrospective, standard-of-care study was conducted through the Pediatric & Congenital Electrophysiology Society. Complications at 30 and 360 days, inappropriate shocks, and delivery of appropriate therapy were assessed.
The study included 115 patients with a median follow-up of 32 (19 to 52) months. Median age was 16.7 years (14.8 to 19.3 years), 29% were female, and 55% had a primary prevention indication. Underlying disease substrate was cardiomyopathy (40%), structural heart disease (32%), idiopathic ventricular fibrillation (16%), and channelopathy (13%). The complication rate was 7.8% at 30 days and 14.7% at 360 days. Overall, inappropriate shocks occurred in 15.6% of patients, with no single clinical characteristic reaching statistical significance. At implant, 97.9% of patients had successful first shock conversion with 96% requiring ≤65 J. Appropriate therapy was delivered to 11.2% of patients with an annual incidence of 3.9% and an acute first shock conversion success rate of 92.5%.
This study found that in a heterogeneous population of pediatric patients and those with congenital heart disease, the S-ICD had comparable rates of complications, inappropriate shocks, and conversion efficacy compared with previously published studies on transvenous systems in similar populations.
Subcutaneous implantable cardioverter defibrillator indication in prevention of sudden cardiac death in difficult clinical situations: A French expert position paper
2020, Archives of Cardiovascular Diseases
Citation Excerpt :
Because of the hypertrophy, some concern exists about the ability of an S-ICD to accurately convert VF. Reassuring data came from Maurizi et al., who reported successful termination of VF by a 65 J shock during acute implantation in all but one of 50 patients with HCM [22]. Lambiase et al. demonstrated that acute VF termination was identical in 99 patients with HCM and 773 without HCM who were implanted with an S-ICD and enrolled in the EFFORTLESS study (successful defibrillation at 80 J achieved in 98.9% of patients with HCM and in 98.5% of patients without HCM) [23].
The introduction of a new technology always raises questions about its place compared with the reference technology. The use of an implantable cardioverter defibrillator to prevent sudden cardiac death is now a widely proven technique, with a clear statement of its indication in the guidelines. More recently, a subcutaneous implantable cardioverter defibrillator has been introduced, and appears to be an attractive technique as it removes the need to implant a lead inside the right ventricle to treat the patient, which should dramatically decrease the risk of complications over time. Currently, only one model of subcutaneous implantable cardioverter defibrillator is available on the market; its indications are the same as for transvenous implantable cardioverter defibrillators, except for patients who need stimulation because of conduction disorders or ventricular tachycardias that can potentially be treated effectively by antitachycardia pacing. The different technical characteristics of transvenous versus subcutaneous implantable cardioverter defibrillators therefore raise the question of which to choose in different clinical settings. The experts who participated in the preparation of this manuscript had three meetings, organized by the company Boston Scientific. Each expert prepared the draft of a section corresponding to a clinical situation. The choice between transvenous versus subcutaneous implantable cardioverter defibrillator was then voted on by all the experts. The results of the votes are presented in this manuscript, as it seemed important to us to show the disparities of opinion that can exist in certain situations. The votes were cast independently and anonymously.
L’intérêt du défibrillateur dans la prévention de la mort subite n’est plus à démontrer. Jusqu’à présent, seul le défibrillateur endocavitaire était disponible. Si cette technique est efficace pour prévenir la mort subite, elle est également sujette à un risque de complications non négligeable (infection, rupture de sonde, choc inapproprié). Avec l’arrivée du défibrillateur sous-cutané, le choix sur la meilleure technique pour prévenir la mort subite est rendu plus complexe, car le défibrillateur sous-cutané a l’avantage de ne pas nécessiter l’implantation d’une sonde en intracardiaque limitant donc le risque de complications, mais par contre, il n’a pas la possibilité de stimuler le cœur ce qui en limite les fonctionnalités. Dans de nombreuses situations, le choix entre un défibrillateur sous-cutané et un défibrillateur endocavitaire n’est pas simple. Le but de cet article est de proposer aux lecteurs un avis d’expert dans ces différentes situations.
Rationale and design of the PRAETORIAN-DFT trial: A prospective randomized CompArative trial of SubcutanEous ImplanTable CardiOverter-DefibrillatoR ImplANtation with and without DeFibrillation testing
2019, American Heart Journal
In transvenous implantable cardioverter-defibrillator (TV-ICD) implants, routine defibrillation testing (DFT) does not improve shock efficacy or reduce arrhythmic death but patients are exposed to the risk of complications related to DFT. The conversion rate of DFT in subcutaneous ICD (S-ICD) is high and first shock efficacy is similar to TV-ICD efficacy rates.
The PRAETORIAN-DFT trial is an investigator-initiated, randomized, controlled, multicenter, prospective two-arm trial designed to demonstrate non-inferiority of omitting DFT in patients undergoing S-ICD implantation in which the S-ICD system components are optimally positioned. Positioning of the S-ICD will be assessed with the PRAETORIAN score. The PRAETORIAN score is developed to systematically evaluate implant position of the S-ICD system components which determine the defibrillation threshold on post-operative chest X-ray. A total of 965 patients, scheduled to undergo a de novo S-ICD implantation without contra-indications for either DFT strategy, will be randomized to either standard of care S-ICD implantation with DFT, or S-ICD implantation without DFT but with evaluation of the implant position using the PRAETORIAN score. The study is powered to claim non-inferiority of S-ICD implantation without DFT in de novo S-ICD patients in respect to the primary endpoint of first shock efficacy in spontaneous arrhythmia episodes. Patients with a high PRAETORIAN score (≥90) in the interventional arm of this study will undergo DFT according to the same DFT protocol as in the control arm.
The PRAETORIAN-DFT trial is a randomized trial that aims to gain scientific evidence to safely omit a routine DFT after S-ICD implantation in patients with correct device positioning.
The subcutaneous implantable cardioverter-defibrillator: Current trends in clinical practice between guidelines and technology progress
2019, European Journal of Internal Medicine
Citation Excerpt :
Of note, inappropriate shocks were mainly due to TWOS [31]. Careful screening for S-ICD compatibility [39,41,42], and improvements in S-ICD discrimination algorithms [43,44] may significantly reduce the incidence of inappropriate shocks. Fig. 2 shows examples of inappropriate and appropriate S-ICD shocks in two HCM patients.
The subcutaneous implantable cardioverter defibrillator (S-ICD) is a valuable alternative to the conventional trans-venous ICD (TV-ICD) for the prevention of sudden cardiac death (SCD). Prospective registries showed that the S-ICD is safe and effective in treating ventricular tachyarrhythmias in high-risk patients without pacing indications. While in earlier studies patients implanted with S-ICDs were young and mostly affected by channelopathies, contemporary S-ICD cohorts include patients with severely impaired left ventricular function and significant comorbidities. This review focuses on S-ICD evidence-based use and highlights current gaps between guidelines recommendations and real-world clinical practice.

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View full text

Effectiveness of subcutaneous implantable cardioverter-defibrillator testing in patients with hypertrophic cardiomyopathy

Abstract

Background

Methods

Results

Conclusions

Introduction

Section snippets

Study population

Demographics and clinical profile

Discussion

Conclusions

Conflict of interest

Acknowledgments

J. Am. Coll. Cardiol.

J. Am. Coll. Cardiol.

J. Am. Coll. Cardiol.

J. Am. Coll. Cardiol.

Heart Rhythm.

J. Am. Coll. Cardiol.

J. Arrhythm.

ESC guidelines on diagnosis and management of hypertrophic cardiomyopathy: the task force for the diagnosis and management of hypertrophic cardiomyopathy of the European Society of Cardiology (ESC)

Eur. Heart J.

2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: executive summary: a report of the American College of Cardiology Foundation/American Heart Association task force on practice guidelines

Circulation

Risk factors for implantable defibrillator lead fracture in a recalled and a nonrecalled lead

J. Cardiovasc. Electrophysiol.