2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Complications and inappropriate shocks in pediatric patients receiving a subcutaneous implantable cardioverter defibrilator

INTRODUCTION AND OBJECTIVES

There is limited evidence regarding the use of subcutaneous implantable cardioverter-defibrillators (S-ICD) in pediatric patients. The aim of this study was to determine the incidence of complications in these patients at our center, according to the type of ICD and patient size.

METHODS

We included all patients aged<18 years who received an S-ICD since 2016 at our center. As a control group, we also included contemporary patients (since 2014) who received a transvenous ICD (TV-ICD). The primary endpoint was a composite of complications and inappropriate shocks.

RESULTS

A total of 26 patients received an S-ICD (median age, 14 [5-17] years; body mass index [BMI], 20.2 kg/m2). Implantation was intermuscular in 23 patients (88%) and subserratus in the remainder. Two incisions were used in 24 patients (92%). In all patients, 2 zones were programmed: a conditional zone set at 230 (220-230) bpm, and a shock zone set at 250 bpm. Nineteen patients received a TV-ICD (median age, 11 [range, 5-16] years; BMI, 19.2 kg/m2, 79% single-chamber). Survival free from the primary endpoint at 5 years was 80% in the S-ICD group and 63% in the TV-ICD group (P=.54). Survival free from inappropriate shocks was similar (85% vs 89%, P=.86), while survival free from complications was higher in the S-ICD group (96% vs 57%, cloglog P=.016). There were no therapy failures in the S-ICD group, and no increased complication rates were observed in patients with BMI ≤20 kg/m2.

CONCLUSIONS

With contemporary implantation techniques and programming, S-ICD is a safe and effective therapy in pediatric patients. The number of inappropriate shocks is similar to TV-ICD, with fewer short- and mid-term complications.

New Guidelines of Pediatric Cardiac Implantable Electronic Devices: What Is Changing in Clinical Practice?

Guidelines are important tools to guide the diagnosis and treatment of patients to improve the decision-making process of health professionals. They are periodically updated according to new evidence. Four new Guidelines in 2021, 2022 and 2023 referred to pediatric pacing and defibrillation. There are some relevant changes in permanent pacing. In patients with atrioventricular block, the heart rate limit in which pacemaker implantation is recommended was decreased to reduce too-early device implantation. However, it was underlined that the heart rate criterion is not absolute, as signs or symptoms of hemodynamically not tolerated bradycardia may even occur at higher rates. In sinus node dysfunction, symptomatic bradycardia is the most relevant recommendation for pacing. Physiological pacing is increasingly used and recommended when the amount of ventricular pacing is presumed to be high. New recommendations suggest that loop recorders may guide the management of inherited arrhythmia syndromes and may be useful for severe but not frequent palpitations. Regarding defibrillator implantation, the main changes are in primary prevention recommendations. In hypertrophic cardiomyopathy, pediatric risk calculators have been included in the Guidelines. In dilated cardiomyopathy, due to the rarity of sudden cardiac death in pediatric age, low ejection fraction criteria were demoted to class II. In long QT syndrome, new criteria included severely prolonged QTc with different limits according to genotype, and some specific mutations. In arrhythmogenic cardiomyopathy, hemodynamically tolerated ventricular tachycardia and arrhythmic syncope were downgraded to class II recommendation. In conclusion, these new Guidelines aim to assess all aspects of cardiac implantable electronic devices and improve treatment strategies.

ICD outcome in pediatric arrhythmogenic cardiomyopathy

BACKGROUND

Arrhythmogenic cardiomyopathy (ACM) is a very rare condition among pediatric patients. Sudden cardiac death (SCD) is the main complication and often requires ICD implantation. Aim of the study is the evaluation of the outcomes of ICD implanted ACM pediatric patients in terms of safety, efficacy and complications.

METHODS

All pediatric patients (<18 y.o.) diagnosed with ACM and who were implanted with ICD since 2009 in Our Institution were collected. Implantation was decided according to current recommendations/ guidelines, and outcome was recorded during follow-up.

RESULTS

Nineteen consecutive ACM patients were implanted with ICD. Subcutaneous ICDs (S-ICD) were implanted in 15 patients (79%) while transvenous ICDs (TV-ICD) in 4 patients (21%). Mean age at implantation was 14.3 ± 2.1 y.o. ICDs were implanted for secondary prevention in 4 (21%) patients, and for primary prevention in 15 (79%). During the follow-up (5.59 ± 3.4 years), appropriate ICD interventions were delivered in 4 (21%) patients for sustained VTs, [2 implanted in primary prevention (13%) and 2 in secondary prevention (50%)]. No defibrillation failures occurred. Inappropriate shocks occurred in 2 cases (10.5%). Device-related complications requiring device revision occurred in 3 (16%): lead dislodgement, surgical skin erosion and sensing defect.

CONCLUSIONS

In a pediatric ACM cohort, appropriate ICD therapies occurred in a minority of primary prevention patients and frequently in secondary prevention patients. The rate of inappropriate shocks and device-related complications were even more rare and mostly wound related. Therefore, ICD therapy in pediatric ACM is effective and safe.

Combined subcutaneous implantable cardioverter defibrillator and pacemaker devices in complex congenital heart disease: a single-center experienced based study

BACKGROUND

Subcutaneous implantable cardioverter defibrillators (S-ICD) are widely accepted therapy in congenital heart disease (CHD) patients at risk of life-threatening ventricular arrhythmias or sudden cardiac death (SCD) when pacing is not required. Occasionally, pacemaker (PM)-dependent CHD patients will subsequently develop an indication for a cardioverter defibrillator. The use of S-ICD in complex CHD patients who have had already PM devices implanted implies some specific considerations, as the safety for these patients in unknown and recommendations among physicians may vary widely.

METHODS

We review the data and studied the indications for S-ICD in complex CHD with previous PM and discuss its usefulness in clinical practice.

RESULTS

From a large cohort of 345 patients enrolled in the S-ICD Monaldi care registry, which encompass all the patients implanted in the Monaldi Hospital of Naples, we considered 11 consecutive complex CHD patients (10M/1F aged 40.4 ±18.4 years) who underwent S-ICD implant after a previous PM implant, from February 2015 to October 2022. Mean follow-up was 25.5 ± 22 months. All the patients showed a good compliance to the device system with no complications (infections or skin erosions).

CONCLUSIONS

In complex CHD with already implanted PM devices, S-ICD implant appears to be a safe alternative to PM upgrading to transvenous ICD system, avoiding abandoned leads or life-threatening lead extraction. However, there are important issues with regard to testing and programming that need to be addressed at the time of implantation.

Analysis of risk stratification and prevention of sudden death in pediatric patients with hypertrophic cardiomyopathy: Dilemmas and clarity

Hypertrophic cardiomyopathy (HCM) has been considered the most common cause of sudden death (SD) in the young. However, introduction of implantable cardioverter-defibrillators (ICDs) in HCM has proved highly effective and the mainstay of preventing SD in children, adolescents, and adults by terminating malignant ventricular tachyarrhythmias. Nevertheless, ICD decision making is generally regarded as more difficult in pediatrics, and the strategy for selecting ICD patients from this population remains without consensus. Prospective studies in HCM children and adolescents have shown the American Heart Association/American College of Cardiology traditional major risk marker strategy to be reliable with >90% sensitivity in selecting patients for SD prevention. International data in >2000 young HCM patients assembled over 20 years who were stratified by major risk markers showed ICDs effectively prevented SD in 20%. Alternatively, novel quantitative risk scoring initiatives provide 5-year risk estimates that are potentially useful as adjunctive tools to facilitate discussion of prophylactic ICD risks vs benefit but are as yet unsupported by prospective outcome studies. Risk scoring strategies are characterized by reasonable discriminatory statistical power (C-statistic 0.69-0.76) for identifying patients with SD events but with relatively low sensitivity, albeit with specificity comparable with the risk marker strategy. While some reticence for obligating healthy-appearing young patients to lifelong device implants is understandable, underutilization of the ICD in high-risk children and adolescents can represent a lost opportunity for fulfilling the long-standing aspiration of SD prevention. This review provides a critical assessment of the current strengths and weaknesses of SD risk stratification strategies in young HCM patients in an effort to clarify clinical decision making in this challenging subpopulation.

Indications and management of implantable cardioverter-defibrillator therapy in childhood hypertrophic cardiomyopathy

Sudden cardiac death is the most common mode of death during childhood and adolescence in hypertrophic cardiomyopathy, and identifying those individuals at highest risk is a major aspect of clinical care. The mainstay of preventative therapy is the implantable cardioverter-defibrillator, which has been shown to be effective at terminating malignant ventricular arrhythmias in children with hypertrophic cardiomyopathy but can be associated with substantial morbidity. Accurate identification of those children at highest risk who would benefit most from implantable cardioverter-defibrillator implantation while minimising the risk of complications is, therefore, essential. This position statement, on behalf of the Association for European Paediatric and Congenital Cardiology (AEPC), reviews the currently available data on established and proposed risk factors for sudden cardiac death in childhood-onset hypertrophic cardiomyopathy and current approaches for risk stratification in this population. It also provides guidance on identification of individuals at risk of sudden cardiac death and optimal management of implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.

Opportunities and drawbacks of the subcutaneous defibrillator across different clinical settings

INTRODUCTION

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an established therapy for the prevention of sudden cardiac death (SCD) and an alternative to a transvenous implantable cardioverter-defibrillator system in selected patients. Beyond randomized clinical trials, many observational studies have described the clinical performance of S-ICD across different subgroups of patients.

AREAS COVERED

Our review aimed to describe the opportunities and drawbacks of the S-ICD, focusing on their use in special populations and across different clinical settings.

EXPERT OPINION

The choice to implant S-ICD should be based on the patient's tailored approach, which takes into account the adequate S-ICD screening at rest or during stress, the infective risk, the ventricular arrhythmia susceptibility, the progressive nature of the underlying disease, the work or sports activity, and the risk of lead-related complications.

Epicardial vs. transvenous implantable cardioverter defibrillators in children

AIMS

The implantable cardioverter defibrillator (ICD) has been increasingly used in children. Both epicardial and transvenous approaches are used, with controversy regarding the best option with no specific recommendations. We aimed to compare outcomes associated with epicardial vs. transvenous ICDs in children.

METHODS AND RESULTS

Data were analysed from a retrospective study including all patients <18-year-old implanted with an ICD in a tertiary centre from 2003 to 2021. Outcomes were compared between epicardial and transvenous ICDs. A total of 122 children with an ICD (mean age 11.5 ± 3.8 years, 57.4% males) were enrolled, with 84 (64.1%) epicardial ICDs and 38 (29.0%) transvenous ICDs. Early (<30 days) ICD-related complications were reported in 17 (20.2%) patients with an epicardial ICD vs. 0 (0.0%) with a transvenous ICD (P = 0.002). Over a mean follow-up of 4.8 ± 4.0 years, 25 (29.8%) patients with an epicardial ICD and 9 (23.7%) patients with a transvenous ICD experienced at least one late ICD-related complication [hazard ratio (HR) 1.8, 95% confidence interval (CI) 0.8-4.0]. Implantable cardioverter defibrillator lead dysfunction occurred in 19 (22.6%) patients with an epicardial ICD vs. 3 (7.9%) with a transvenous ICD (HR 5.7, 95% CI 1.3-24.5) and was associated with a higher incidence of ICD-related reintervention (HR 3.0, 95% CI 1.3-7.0). After considering potential confounders, especially age and weight at implantation, this association was no longer significant (P = 0.112). The freedom from ICD lead dysfunction was greater in patients with pleural coils than in those with epicardial coils (HR 0.38, 95% CI 0.15-0.96).

CONCLUSION

In children, after a consideration of patient characteristics at implantation, the burden of complications and ICD lead dysfunction appears to be similar in patients with epicardial and transvenous devices. Pleural coils seem to be associated with better outcomes than epicardial coils in this population.

CLINICAL TRIAL REGISTRATION

NCT05349162.

Subcutaneous versus transvenous implantable cardioverter defibrillators in children and young adults: A meta-analysis

INTRODUCTION

The implantable cardioverter defibrillator (ICD) has been demonstrated to successfully prevent sudden cardiac death (SCD) in children and young adults. A wide range of device-related complications/malfunctions have been described, which depend on the intrinsic design of the defibrillation system (transvenous-implantable cardioverter defibrillator [TV-ICD] vs. subcutaneous-implantable cardioverter defibrillator [S-ICD]).

OBJECTIVE

To compare the device-related complications and inappropriate shocks with TV-ICD versus S-ICD.

METHODS AND RESULTS

Electronic databases were queried for studies focusing on the prevention of SCD in children and young adults with TV-ICD or S-ICD. The effect size was estimated using a random-effect model as odds ratio (OR) and relative 95% confidence interval (CI). The primary endpoint was a composite of any device-related complications and inappropriate shocks. We identified a total of five studies including 236 patients (Group S-ICD: 76 patients; Group TV-ICD: 160 patients) with a mean follow-up time of 54.2 ± 24.9 months. S-ICD implantation contributed to a significant reduction in the risk of the primary endpoint of any device-related complications and inappropriate shocks (OR: 0.18; 95% CI: 0.05-0.73; p = .02). S-ICD was also associated with a significantly lower incidence of inappropriate shocks (OR: 0.28; 95% CI: 0.11-0.74; p = .01) and lead-related complications (OR: 0.18; 95% CI: 0.05-0.66; p = .01). A trend toward a higher risk of pocket complications (OR: 5.91; 95% CI: 0.98-35.63; p = .05) was recorded in patients with S-ICD.

CONCLUSION

Children and young adults undergoing S-ICD implantation may have a lower risk of a composite of device-related complications and inappropriate shocks, compared to TV-ICD patients.

Subcutaneous Implantable Cardioverter Defibrillators for the Prevention of Sudden Cardiac Death: Pediatric Single-Center Experience

BACKGROUND

The subcutaneous implantable cardioverter defibrillator (S-ICD) was developed as an alternative to the transvenous ICD, to prevent lead-related complications associated with the latter. The absence of intravascular or intracardiac components offers potential advantages to pediatric patients.

AIMS

The aim of the study is to present an overview of our experience with S-ICDs in the pediatric center that, currently, has performed the largest number of implantations in children in Poland.

METHODS

Retrospective analysis of data from medical history, qualification, implantation procedure, and S-ICD post-implantation observations in 11 pediatric patients were performed.

RESULTS

S-ICDs were implanted in 11 patients, 8 boys and 3 girls, aged 12-17 years. The S-ICD was implanted for primary prevention in seven patients: four with hypertrophic cardiomyopathy (HCM), two with dilated cardiomyopathy (DCM), and one with arrhythmogenic right ventricular cardiomyopathy (ARVC). It was implanted for secondary prevention in four patients: two with sudden cardiac arrest (SCA) in the course of idiopathic ventricular fibrillation (IVF), one with long QT syndrome (LQTS) after probable SCA, and one with Brugada syndrome after SCA. In all patients, the device was implanted intramuscularly. One patient did not have a defibrillation test performed due to the presence of an intracardiac thrombus. In one patient, during screening, it was decided to implant an electrode on the right side of the sternum. There were no early or late complications with any of the procedures. So far, no inadequate discharges have been observed.

CONCLUSIONS

Our results prove the efficacy of the S-ICD treatment option along with technically simple surgery, which supports its further and more widespread application in children.

The SIDECAR project: S-IcD registry in European paediatriC and young Adult patients with congenital heaRt defects

AIMS

Subcutaneous-implantable cardiac defibrillators (S-ICDs) are used increasingly to prevent sudden cardiac death in young patients. This study was set up to gain insight in the indications for S-ICD, possible complications, and their predictors and follow-up results.

METHODS AND RESULTS

A multicentre, observational, retrospective, non-randomized, standard-of-care registry on S-ICD outcome in young patients with congenital heart diseases (CHDs), inherited arrhythmias (IAs), idiopathic ventricular fibrillation (IVF), and cardiomyopathies (CMPs). Anthropometry was registered as well as implantation technique, mid-term device-related complications, and incidence of appropriate/inappropriate shocks (IASs). Data are reported as median (interquartile range) or mean ± standard deviation. Eighty-one patients (47% CMPs, 20% CHD, 21% IVF, and 12% IA), aged 15 (14-17) years, with body mass index (BMI) 21.8 ± 3.8 kg/m2, underwent S-ICD implantation (primary prevention in 59%). This was performed with two-incision technique in 81% and with a subcutaneous pocket in 59%. Shock and conditional zones were programmed at 250 (200-250) and 210 (180-240) b.p.m., respectively. No intraoperative complications occurred. Follow up was 19 (6-35) months: no defibrillation failure occurred, 17% of patients received appropriate shocks, 13% of patients received IAS (supraventricular tachycardias 40%, T-wave oversensing 40%, and non-cardiac oversensing 20%). Reprogramming, proper drug therapy, and surgical revision avoided further IAS. Complications requiring surgical revision occurred in 9% of patients, with higher risks in patients with three-incision procedures [hazard ratio (HR) 4.3, 95% confidence interval (95% CI) 0.5-34, P = 0.038] and BMI < 20 (HR 5.1, 95% CI 1-24, P = 0.031).

CONCLUSION

This multicentre European paediatric registry showed good S-ICD efficacy and safety in young patients. Newer implantation techniques and BMI > 20 showed better outcome.

S-ICDs: advantages and opportunities for improvement

INTRODUCTION

The subcutaneous implantable cardioverter defibrillator (S-ICD) is currently in its third generation and has been adopted in guidelines and in mainstream clinical practice. Considerable improvements have been made since the introduction of this device over a decade ago.

AREAS COVERED

A literature search was undertaken in Pubmed on articles relating to the S-ICD.

EXPERT OPINION

The therapy has been proven to be safe and effective and is a valuable option in selected patients. Nevertheless, there remain many shortcomings of the S-ICD which are discussed in this review, and which hopefully will be addressed by future generations of the device.

ICD Outcome in Pediatric Cardiomyopathies

Background: Pediatric patients with cardiomyopathies are at risk of malignant arrhythmias and sudden cardiac death (SCD). An ICD may prevent SCD. The aim of this study was to evaluate ICD implantation outcomes, and to compare transvenous and subcutaneous ICDs (S-ICDs) implanted in pediatric patients with cardiomyopathies. Methods: The study is single center and retrospective, and includes pediatric patients with cardiomyopathies who required ICD implantation (2010–2021). Outcomes were recorded for appropriate/inappropriate ICD therapy and surgical complications. Transvenous ICD and S-ICD were compared. Data are presented as median values (25th–75th centiles). Results: Forty-four patients with cardiomyopathies (hypertrophic 39%, arrhythmogenic 32%, dilated 27%, and restrictive 2%) underwent transvenous (52%) and S-ICD (48%) implantation at 14 (12–17) years of age, mostly for primary prevention (73%). The follow-up period was 29 (14–60) months. Appropriate ICD therapies were delivered in 25% of patients, without defibrillation failures. Lower age at implantation and secondary prevention were significant risk factors for malignant ventricular arrhythmias that required appropriate ICD therapies. ICD-related complications were surgical complications (18%) and inappropriate shocks (7%). No significant differences in outcomes were recorded, either when comparing transvenous and S-ICD or comparing the different cardiomyopathies. Conclusions: In pediatric patients with cardiomyopathy, ICD therapy is effective, with a low rate of inappropriate shocks. Neither ICD type (transvenous and S-ICDs) nor the cardiomyopathies subgroup revealed divergent outcomes.

Implantable cardioverter-defibrillators for hypertrophic cardiomyopathy: The Times They Are a-Changin'

The implantable cardioverter-defibrillator (ICD) is a life-saving therapy in patients with hypertrophic cardiomyopathy (HCM) at high risk of sudden cardiac death. The heterogeneity of clinical scenarios in HCM and the availability of ICDs with distinct characteristics emphasizes the need for selecting the right device for the right patient. There is growing awareness that unnecessarily complex devices can lead to short- and long-term complications without adding significant clinical benefits. Young patients have the greatest potential years of life gained from the ICD but are also most exposed to device-related complications. This increases the complexity of decision-making of ICD prescription in these often otherwise well patients in whom device selection should be tailored to preserve survival benefit without introducing morbidity. In the light of the multiple clinical phenotypes characterizing HCM, the present article offers evidence-based perspectives helpful in predicting the individual impact of the ICD and choosing the most appropriate device.

Efficacy of a Subcutaneous Implantable Cardioverter Defibrillator in a Child with Early Repolarization Syndrome

An early repolarization (ER) pattern or J waves are considered to be a benign finding observed in the healthy population, however, it has been pointed out that the ER pattern seen in the inferolateral leads could be an independent risk factor for fatal arrhythmias. We present a pediatric case in which early repolarization syndrome (ERS) was suspected due to the presence of ER or J waves in the inferior leads, which eventually disappeared after the administration of pilsicainide. During the follow-up period, several fatal ventricular arrhythmias were recorded after implantation of a subcutaneous implantable cardiac defibrillator (S-ICD). This report describes the efficacy of S-ICDs in a child with an ER pattern after aborted sudden cardiac death.

Subcutaneous implantable cardioverter defibrillator in children and adolescents: results from the S-ICD "Monaldi care" registry

BACKGROUND

Implantable cardioverter defibrillators (ICD) are widely accepted therapy in children and adolescents who are survivors of cardiac arrest or for high-risk patients with inheritable channelopathies, cardiomyopathies, or congenital heart disease. Initial experience with subcutaneous ICD (S-ICD) systems has shown a high efficacy in adults. However, the use of S-ICD in children and adolescents implies some specific considerations, as the safety for these patients is unknown and recommendations among physicians may vary widely.

METHODS

We reviewed the data and studied the indications for S-ICD in children and adolescents and discuss the preliminary clinical experience.

RESULTS

From a cohort of 297 patients enrolled in the S-ICD "Monaldi care" registry that encompass all the patients implanted in the Monaldi Hospital of Naples, we considered 21 consecutive children and adolescents (mean age 13.9 years, range 8-18 years, mean body weight 59.3 kg, range 38-100 kg) who underwent S-ICD implant from April 2014 to June 2020. Mean follow-up was 41.9±21.9 months. Only one patient presented, 6 weeks after implantation, skin erosion at the inferior parasternal incision that resolved after antibiotic therapy, without the necessity of any system revision. Two patients experienced appropriate shocks and four inappropriate shocks, due to T wave oversensing or atrial arrhythmia. Only one patient, with arrhythmogenic right ventricular dysplasia, required a system revision after 36 months of the first implantation and then a reintervention with a replacement of the S-ICD by a conventional ICD system.

CONCLUSIONS

Our experience suggests that the S-ICD device can be used in some children over the age of 8 as well as adults, with a similar rate of unwanted side effects, and early evidence of apparent efficacy.

2020 MR Safety for Cardiac Devices: An Update for Radiologists

Magnetic resonance imaging (MRI) is a unique and powerful diagnostic tool that provides images without ionizing radiation and, at times, can be the only modality to properly assess and diagnose some pathologies. Although many patients will need an MRI in their lifetime, many of them are still being unjustly denied access to it due to what were once considered absolute contraindications, including MR nonconditional pacemakers and implantable cardioverter-defibrillators. However, there are a number of large studies that have recently demonstrated that MRI can safely be performed in these patients under certain conditions. In addition, there are an increasing number of novel cardiac devices implanted in patients who may require an MRI. Radiologists need to familiarize themselves with these devices, identify which patients with these devices can safely undergo MRI, and under which conditions. In this article, we will review the current literature on MR safety and cardiac devices, elaborate on how to safely image patients with cardiac devices, and share the expertise of our tertiary cardiac institute.

Pediatric SubQ-ICD implantation, a single center review of the inter-muscular technique

INTRODUCTION

Pediatric patients with cardiomyopathies are at risk for sudden death and may need implantable cardioverter defibrillators (ICD's), but given their small size and duration of use, children are at increased risk for complications associated with ICD use. The subcutaneous ICD presents a favorable option for children without pacing indications. Unfortunately, initial pediatric studies have demonstrated a high complication rate, likely due to the 3-incision technique employed.

MATERIAL AND METHODS

Patients with ICD but no pacing indication were retrospectively reviewed after implantation of subcutaneous ICD via the two-incision technique. In half of the patients, 10-J impedance test was also performed to compare with impedance obtained after defibrillation threshold testing with 65-J.

RESULTS

Twelve patients were included. The median age was 14 years (range 10-16 years) with eight males included (72.7%). The median weight was 55 kg (range 29 kg-75.1 kg). Follow-up had a median of 11.5 months (range 2-27 months). The median body mass index was 18.4 kg/m squared (range 15.5-27.9 kg/m squared). One patient suffered a minor complication after tearing off the incisional adhesive strips early and required a non-invasive repair in clinic. Shock impedance had a median of 55 J (range 48-68 J). There was one appropriate shock/charge and no inappropriate shocks during follow-up.

CONCLUSION

The two-incision, intermuscular technique appears to have a lower acute complication rate than prior reports, in our cohort of 12 pediatric patients.

A Numerical Evaluation of Multi-Lead Subcutaneous Implantable Cardioverter Defibrillator for Low Energy and Less Damage in Swine

In the rescue of patients with sudden cardiac death, cardiac electric defibrillation is usually implemented, but the myocardial damage caused by exceeding defibrillation shock is irreversible. The aim of this study is to provide a numerically implanted optimization of a subcutaneous implantable cardioverter defibrillator (S-ICD) for low shock energy and less myocardial damage. In this paper, three anatomically realistic finite element models of swine were constructed for the evaluation study of six Can-Lead configurations with various number of leads at different placements. For each Can-Lead configuration, corresponding numerical modeling and simulation with the finite element method (FEM) were performed to pre-surgically assess quantitatively the efficiency of a certain defibrillation shock, besed on our previously reported multi-criteria evaluation of cardiac defibrillation. The results show that the outcome of an S-ICD shock depends on numbers of the implanted leads as well as the location of Can-Lead, and suggest that an S-ICD implantation with a left pectoral Can and two leads (located at the midline and at the left last ribs oblique upward) would possess the best efficiency of defibrillation, which could offer another option in clinical practice. In conclusion, on basis of the pre-surgical simulation of an S-ICD configuration, an individual optimization of cardiac defibrillation would be potentially useful for a lower energy and a less myocardial damage compared with current implantations with only the knowledge of clinical practices.

Sudden Cardiac Death in Children Affected by Cardiomyopathies: An Update on Risk Factors and Indications at Transvenous or Subcutaneous Implantable Defibrillators

In the present paper, we will discuss the main cardiomyopathies affecting children with a specific focus on risk stratification and prevention of sudden cardiac death (SCD). We will discuss the main clinical features of hypertrophic cardiomyopathy (HCM), dilated and restrictive cardiomyopathies, left ventricular non-compaction (LVNC) and arrhythmogenic cardiomyopathy (AC), always highlighting their peculiarities in the pediatric age. Since sudden cardiac death may be the first manifestation of the disease, even in children, the identification of the specific underlying condition and of risk factors are pivotal to carry out the appropriate preventing strategies. ICD recommendations in children are similar to adults, but supporting evidences are not so solid, being based on registries or single center studies. Furthermore, children and young patients are most likely to manifest long term complications related to an implanted ICD, and this should be taken into account when evaluating the risk benefit ratio. In this perspective, subcutaneous ICDs (S-ICDs) could carry an advantage; however, they cannot be considered in small children for technical reasons. Data on effectiveness and safety of S-ICDs in a pediatric population is still lacking, although some limited experiences are reported and will be discussed in the current review.

Successful defibrillation verification in subcutaneous implantable cardioverter-defibrillator recipients by low-energy shocks

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an effective alternative to the transvenous one. Defibrillation efficacy depends on maximum device output and on the optimal device location at device implantation.

HYPOTHESIS

We sought to investigate the defibrillation safety margin in real life clinical practice.

METHODS

We sought to understand what is the efficacy of induced ventricular fibrillation (VF) termination at S-ICD implantation using lower energies than the recommended 65 J.

RESULTS

Sixty-four consecutive S-ICD recipients underwent VF termination attempts at implantation with energies ranging from 20 to 50 J. Overall, VF termination occurred in 84% of patients with ≤40 J, in 88% with 45 J, and in 100% with 60 J. Intermuscular S-ICD placement was associated with 94% VF termination at ≤40 J. An ejection fraction <35% was associated to higher energy requirement for defibrillation; however, an intermuscular S-ICD placement conferred 90% defibrillation efficacy at 31 ± 5 J in this patients subset.

CONCLUSIONS

This is a hypothesis-generating observation that prompts a methodologically correct investigation to prove that a 60 J output S-ICD can provide an adequate safety margin to terminate VF in clinical practice. This would enable superior device longevity and/or device downsizing for pediatric/small size patients.

Spotlight on S-ICD™ therapy: 10 years of clinical experience and innovation

Subcutaneous ICD (S-ICD™) therapy has been established in initial clinical trials and current international guideline recommendations for patients without demand for pacing, cardiac resynchronization, or antitachycardia pacing. The promising experience in ‘ideal’ S-ICD™ candidates increasingly encourages physicians to provide the benefits of S-ICD™ therapy to patients in clinical constellations beyond ‘classical’ indications of S-ICD™ therapy, which has led to a broadening of S-ICD™ indications in many centres. However, the decision for S-ICD™ implantation is still not covered by controlled randomized trials but rather relies on patient series or observational studies. Thus, this review intends to give a contemporary update on available empirical evidence data and technical advancements of S-ICD™ technology and sheds a spotlight on S-ICD™ therapy in recently discovered fields of indication beyond ideal preconditions. We discuss the eligibility for S-ICD™ therapy in Brugada syndrome as an example for an adverse and dynamic electrocardiographic pattern that challenges the S-ICD™ sensing and detection algorithms. Besides, the S-ICD™ performance and defibrillation efficacy in conditions of adverse structural remodelling as exemplified for hypertrophic cardiomyopathy is discussed. In addition, we review recent data on potential device interactions between S-ICD™ systems and other implantable cardio-active systems (e.g. pacemakers) including specific recommendations, how these could be prevented. Finally, we evaluate limitations of S-ICD™ therapy in adverse patient constitutions, like distinct obesity, and present contemporary strategies to assure proper S-ICD™ performance in these patients. Overall, the S-ICD™ performance is promising even for many patients, who may not be ‘classical’ candidates for this technology.