Inappropriate ICD shocks in pediatrics and congenital heart disease patients: Risk factors and programming strategies

Prediction of Sudden Death Risk in Patients with Congenital Heart Diseases

Risk stratification for sudden death should be discussed with patients with congenital heart disease at each stage of personal and cardiac development. For most patients, risk is low through teenage years and the critical factors to consider are anatomy, ventricular function, and symptoms. By adulthood, these are supplemented by screening for atrial arrhythmias, ventricular arrhythmias, and pulmonary hypertension. Therapies include medication, ablation, and defibrillator placement.

Low Risk of Inappropriate Shock Among Pediatric Patients With an Implantable Cardioverter Defibrillator: A Single Center Experience

Implantable cardioverter-defibrillators (ICD) are increasingly being used among the pediatric population for indications of both primary and secondary prevention. There is limited long-term data on the outcomes of pediatric patients following ICD implantation. The aim of this study was to investigate the characteristics of this population, burden of appropriate and inappropriate shock and complication rate in a large tertiary pediatric medical center. Included were children under the age of 18 years who underwent ICD implantation and had clinical follow up at our center. Data were retrospectively collected between study period 2005-2020. Primary outcome was the incidence of ICD shock appropriate and inappropriate. Secondary outcome was defining our patient population characteristics. Our cohort included 51 patients who underwent ICD implantation. Mean age at implantation was 10.9 ± 4.7 years and average follow-up time was 67 months. Diagnoses of implanted patients were: 28 (55%) patients with syndromes with risk for sudden death, cardiomyopathy in 14 patients (27%) and congenital heart disease (CHD) in 9 patients (18%). Forty-two (82%) patients had an ICD implanted for secondary prevention after experiencing a life-threatening arrhythmia and 9 (18%) for primary prevention. An endocardial system was implanted in 39 (76%) patients and an epicardial systems in 12 (24%) patients. A total of 20 (39%) patients received appropriate shocks for ventricular fibrillation(VF). 5 patients received inappropriate shocks, 4 due to sinus tachycardia and 1 due to rapidly conducted atrial fibrillation. Those who received an inappropriate shock had a significantly shorter ICD-programmed VF detection cycle length compared to those who did not receive an inappropriate shock (320 ms versus 270 ms, p = 0.062). This single center study demonstrates a high rate of appropriate ICD shocks (39%) and a low rate of inappropriate ICD shocks. Accurate programming of ICD devices in the pediatric population is paramount to avoid inappropriate ICD shocks.

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.

The Case for Home AED in Children, Adolescents, and Young Adults Not Meeting Criteria for ICD

Children, adolescents, and young adults with conditions such as cardiomyopathies and channelopathies are at higher risk of sudden cardiac death caused by lethal arrhythmias, especially ventricular fibrillation. Timely defibrillation saves lives. Patients thought to be at significantly high risk of sudden death typically undergo placement of an implantable cardioverter-defibrillator. Patients thought to be at lower risk are typically followed medically but do not undergo implantable cardioverter-defibrillator placement. However, low risk does not equal no risk. Compared with the general population, many of these patients are at significantly higher risk for lethal arrhythmias. We make the case that such individuals and families will benefit from having an at-home automatic external defibrillator. Used in conjunction with conventional measures such as training on cardiopulmonary resuscitation, an at-home automatic external defibrillator could lead to significantly shortened time to defibrillation with better overall and neurological survival. We recommend that the cost of such home automatic external defibrillators should be covered by medical insurance.

Peak Oxygen Uptake on Cardiopulmonary Exercise Test Is a Predictor for Severe Arrhythmic Events during Three-Year Follow-Up in Patients with Complex Congenital Heart Disease

Patients with congenital heart disease (CHD) are at increased risk for severe arrhythmia and sudden cardiac death (SCD). Although implantable cardioverter defibrillators (ICD) effectively prevent SCD, risk stratification for primary prophylaxis in patients with CHD remains challenging. Patients with complex CHD undergoing CPET were included in this single-center study. Univariable and backwards stepwise multivariable logistic regression models were used to identify variables associated with the endpoint of severe arrhythmic event during three years of follow-up. Cut-off values were established with receiver operating characteristic (ROC) curve analysis. Survival analysis was conducted via Kaplan–Meier plots. Severe Arrhythmia was documented in 97 of 1194 patients (8.1%/3 years). Independent risk factors for severe arrhythmia during follow-up were old age and a low peak oxygen uptake (V.O2peak) on multivariable analysis. Patients with more advanced age and with V.O2peak values of less than 24.9 mL/min/kg were at significantly increased risk for the occurrence of severe arrhythmias during follow-up. The combined analysis of both risk factors yielded an additional benefit for risk assessment. Age at CPET and V.O2peak predict the risk for severe arrhythmic events and should be considered for risk stratification of SCD in patients with complex CHD.

Implantable Cardioverter Defibrillators in Infants and Toddlers: Indications, Placement, Programming, and Outcomes

BACKGROUND

Limited data exist regarding implantable cardioverter defibrillator (ICD) usage in infants and toddlers. This study evaluates ICD placement indications, procedural techniques, programming strategies, and outcomes of ICDs in infants and toddlers.

METHODS

This is a single-center retrospective review of all patients ≤3 years old who received an ICD from 2009 to 2021.

RESULTS

Fifteen patients received an ICD at an age of 1.2 years (interquartile range [IQR], 0.1-2.4; 12 [80%] women; weight, 8.2 kg [IQR, 4.2-12.6]) and were followed for a median of 4.28 years (IQR, 1.40-5.53) or 64.2 patient-years. ICDs were placed for secondary prevention in 12 patients (80%). Diagnoses included 8 long-QT syndromes (53%), 4 idiopathic ventricular tachycardias/ventricular fibrillations (VFs; 27%), 1 recurrent ventricular tachycardia with cardiomyopathy (7%), 1 VF with left ventricular noncompaction (7%), and 1 catecholaminergic polymorphic ventricular tachycardia (7%). All implants were epicardial, with a coil in the pericardial space. Intraoperative defibrillation safety testing was attempted in 11 patients (73%), with VF induced in 8 (53%). Successful restoration of sinus rhythm was achieved in all tested patients with a median of 9 (IQR, 7.3-11.3) J or 0.90 (IQR, 0.68-1.04) J/kg. Complications consisted of 1 postoperative chylothorax and 3 episodes of feeding intolerance. VF detection was programmed to 250 (IQR, 240-250) ms with first shock delivering 10 (IQR, 5-15) J or 1.1 (IQR, 0.8-1.4) J/kg. Three patients (20%) received appropriate shocks for ventricular tachycardia/VF. No patient received an inappropriate shock. There were 2 (13%) ventricular lead fractures (at 2.6 and 4.2 years post-implant), 1 (7%) pocket-site infection, and 2 (13%) generator exchanges. All patients were alive, and 1 patient (7%) received a heart transplant.

CONCLUSIONS

ICDs can be safely and effectively placed for sudden death prevention in infants and toddlers with good midterm outcomes.

Hypoplastic coronary artery disease and hypertension in a child: a case report

Background

Hypoplastic coronary artery disease (HCAD) is an extremely rare disease associated with a risk of sudden cardiac death. It is rarely recognized in a live paediatric patient.

Case summary

We report a case of HCAD in a patient who first presented with vomiting and poor feeding, suggestive of acute heart failure due to cardiomyopathy or acute myocarditis in infancy. Hypertension and signs of ischaemia became evident on electrocardiography and scintigraphy after his cardiac function fully recovered, and he was diagnosed with HCAD by angiography performed at the age of 8 years. He has remained under close observation with anti-hypertensives, aspirin, and exercise restriction.

Discussion

Although HCAD is a rare disease, it may not only cause ischaemia but may also result in heart failure and sudden cardiac death. It should be considered in any paediatric patient with heart failure. Mid-term follow-up visits might be necessary to detect signs of ischaemia in paediatric patients presenting with features of heart failure.

Inappropriate shock delivery by an implantable cardioverter-defibrillator due to electrical interference with a refrigerator in a 4-year-old child

We report a patient with long QT syndrome who received an inappropriate implantable cardioverter-defibrillator shock due to electrical interference from a refrigerator. This electrical interference was mistakenly detected as an episode of ventricular fibrillation and ended with an inappropriate delivery of shock without any warning symptoms before.

Clinical outcomes and programming strategies of implantable cardioverter-defibrillator devices in paediatric hypertrophic cardiomyopathy: a UK National Cohort Study

AIMS

Sudden cardiac death (SCD) is the most common mode of death in paediatric hypertrophic cardiomyopathy (HCM). This study describes the implant and programming strategies with clinical outcomes following implantable cardioverter-defibrillator (ICD) insertion in a well-characterized national paediatric HCM cohort.

METHODS AND RESULTS

Data from 90 patients undergoing ICD insertion at a median age 13 (±3.5) for primary (n = 67, 74%) or secondary prevention (n = 23, 26%) were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM from the UK. Seventy-six (84%) had an endovascular system [14 (18%) dual coil], 3 (3%) epicardial, and 11 (12%) subcutaneous system. Defibrillation threshold (DFT) testing was performed at implant in 68 (76%). Inadequate DFT in four led to implant adjustment in three patients. Over a median follow-up of 54 months (interquartile range 28-111), 25 (28%) patients had 53 appropriate therapies [ICD shock n = 45, anti-tachycardia pacing (ATP) n = 8], incidence rate 4.7 per 100 patient years (95% CI 2.9-7.6). Eight inappropriate therapies occurred in 7 (8%) patients (ICD shock n = 4, ATP n = 4), incidence rate 1.1/100 patient years (95% CI 0.4-2.5). Three patients (3%) died following arrhythmic events, despite a functioning device. Other device complications were seen in 28 patients (31%), including lead-related complications (n = 15) and infection (n = 10). No clinical, device, or programming characteristics predicted time to inappropriate therapy or lead complication.

CONCLUSION

In a large national cohort of paediatric HCM patients with an ICD, device and programming strategies varied widely. No particular strategy was associated with inappropriate therapies, missed/delayed therapies, or lead complications.

Implantable cardioverter-defibrillator therapy to reduce sudden cardiac death in adults with congenital heart disease: A registry study

INTRODUCTION

The adult congenital heart disease (ACHD) population is rapidly expanding. However, a significant proportion of these patients suffer sudden cardiac death. Recommending implantable cardioverter-defibrillator (ICD) insertion requires balancing the need for appropriate therapy in malignant arrhythmia against the consequences of inappropriate therapy and procedural complications. Here we present long-term follow-up data for ICD insertion in patients with ACHD from a large Level 1 congenital cardiac center.

METHODS AND RESULTS

All patients with ACHD undergoing ICD insertion over an 18-year period were identified. Data were extracted for baseline characteristics including demographics, initial diagnosis, ventricular function, relevant medication, and indication for ICD insertion. Details regarding device insertion were gathered along with follow-up data including appropriate and inappropriate therapy and complications. A total of 136 ICDs were implanted during this period: 79 for primary and 57 for secondary prevention. The most common congenital cardiac conditions in both groups were tetralogy of Fallot and transposition of the great arteries. Twenty-two individuals in the primary prevention group received appropriate antitachycardia pacing (ATP), 14 underwent appropriate cardioversion, 17 received inappropriate ATP, and 15 received inappropriate cardioversion. In the secondary prevention group, 18 individuals received appropriate ATP, 8 underwent appropriate cardioversion, 8 received inappropriate ATP, and 7 were inappropriately cardioverted. Our data demonstrate low complication rates, particularly with leads without advisories.

CONCLUSION

ICD insertion in the ACHD population involves a careful balance of the risks and benefits. Our data show a significant proportion of patients receiving appropriate therapy indicating that ICDs were inserted appropriately.

Defibrillators in adult congenital heart disease: Long-term risk of appropriate shocks, inappropriate shocks, and complications

AIMS

Sudden cardiac death (SCD) accounts for up to 25% of deaths in the adult congenital heart disease (ACHD) population. Current guidelines for defibrillator implantation are either extrapolated from acquired cardiac disease or are based upon single lesion studies, predominantly Tetralogy of Fallot (TOF). Defibrillator-related morbidity appears to be substantially higher in ACHD patients.

METHODS

We retrospectively evaluated all patients in our ACHD database who received an implantable cardioverter-defibrillator (ICD) between 2000 and 2019, and who were ≥16 years old at time of implant. Patients were followed for appropriate shocks, inappropriate shocks, and complications.

RESULTS

Of 4748 patients in our database, 59 patients (1.2%) underwent ICD implantation. ICDs were for primary prevention in 63% and secondary prevention in 37%. Over a median follow-up of 6.6 years, 24% received an appropriate shock, 27% an inappropriate shock, and 42% suffered a device-related complication (annualized risks of 3.2%, 3.6%, and 5.7%, respectively). There were no significant predictors of appropriate shocks or inappropriate shocks. All appropriate shocks in primary prevention patients occurred in TOF or transposition of the great arteries (TGA) with atrial switch, typically in the presence of multiple SCD risk factors. The majority of inappropriate shocks were due to supraventricular arrhythmias. Device-related mortality was 1.7% (0.3% per annum).

CONCLUSIONS

Appropriate shocks were relatively common in an ACHD ICD population followed in the long term. Device-related morbidity was significant. Although risk factors have been established for TOF, and to a lesser extent TGA, risk stratification for ICD implantation in ACHD remains challenging.

Cardiac resynchronization and implantable defibrillators in adults with congenital heart disease

Cardiac resynchronization therapy (CRT) and implantable cardioverter defibrillators (ICDs) are well-established therapies for adult patients with heart failure that have been shown to improve morbidity and mortality. However, the benefits and indications for use in adults with congenital heart disease (ACHD) are less defined with no significant large prospective studies in this population. There are, however, multiple retrospective studies that demonstrate the efficacy of these devices in the ACHD population. These indicate a role for both CRT and ICDs in select patients with ACHD. The clinician and patient must balance the risks and benefits, summarized in complex evidence that reflects the heterogeneity of the ACHD patient group, and apply them in a patient-specific manner to optimize the utility of CRT and ICDs.

Modern Technology for Prevention of Sudden Cardiac Death – a Clinical Update on Device Therapy in Children with Congenital Heart Diseases

Sudden cardiac death in children is one of the most devastating conditions that can be encountered in acute cardiac care. Intracardiac device therapy, providing prompt and effective treatment in malignant ventricular arrhythmia or in severe conduction abnormalities, is a promising tool to reduce the incidence of this fatal condition. However, the implementation of device-based therapy in the pediatric population is currently limited by the lack of clinical studies on large number of subjects. As a result, indications for device therapy in pediatric patients are still unclear in many circumstances. There are also several particularities related to device implantation in pediatric age, such as the somatic growth leading to a mismatch between chamber size and lead length, or the difficulties of implantation technique in children with small body weight. This study aims to present an update on the current advantages and limitations of device-based therapy for treating severe malignant arrhythmia or conduction disorders in children at risk for sudden cardiac death.

Long-term single-center experience of defibrillator therapy in children and adolescents

BACKGROUND

Implantable cardioverter-defibrillator (ICD) systems are established therapy for prevention of sudden cardiac death. Long-term data on ICD systems in children and adolescents is rare. The present study displays a long-term single-center follow-up of children and adolescents with ICD systems.

METHODS AND RESULTS

The present study represents a single-center experience of patients younger than 18 years who received an ICD (n = 58). Follow-up data included in-house follow-up as well as examinations of collaborating specialists. Mean age at implantation was 14.0 ± 3.3 years and 33 patients (56.9%) were male. A transvenous ICD system was implanted in 54 patients (93.1%). In 33 patients (56.9%) electrical heart disease or idiopathic ventricular fibrillation represented the underlying condition of ICD implantation. Median follow-up duration was 70 months (45; 94). 3 patients (5.2%) died during the observation period. None of these deaths was associated with ICD failure. Appropriate shocks occurred in 32 patients (55.2%). Inappropriate shock delivery was recorded in 17 patients (29.3%). Supraventricular tachycardia represented the most frequent cause of inappropriate shock delivery (9 patients, 52.9%). T-wave oversensing led to inappropriate shock delivery in 3 patients (17.6%). In 5 patients (29.4%), lead failure caused inappropriate shock delivery. Of note, during follow-up lead failure was reported in 15 patients (25.9%) leading to surgical revision.

CONCLUSION

ICD therapy in children and adolescents is effective for prevention of sudden cardiac death. The rate of appropriate shock deliveries was significantly higher as compared with large ICD trials. Inappropriate therapies occurred frequently. In particular supraventricular tachycardia, T-wave oversensing and lead failures were responsible for these episodes.

The Capture Gap: Implantable Cardioverter-Defibrillator Quality of Life

We aimed to compare salient characteristics and antecedents of quality of life (QOL) in adolescents and young adults with implantable cardioverter-defibrillators (ICDs) from qualitative methods with quantitative measurement of QOL and correlations between QOL (PedsQL) and measured participant characteristics. Concurrent parallel mixed methods design was used to collect survey data from the PedsQL electronic health record, demographic questionnaire, and semistructured interview data. A convenience sample of 16 individuals with ICDs, aged 13 to 25 years, was obtained from a tertiary pediatric facility. Overall QOL and subdomains of physical, psychosocial, and academic/work were examined by PedsQL and visual analog scale. Select demographics were collected to develop a participant profile. Females with ICDs appear to be at risk of poor QOL given some unknown factors. Financial status of the individual and the family was positively related to QOL. For new ICD persons involved in physical activities that must be stopped, peer support appears to improve QOL.

Assessing Candidacy for Primary Preventative Implantable Cardioverter-defibrillators in Pediatric Patients with Ion Channelopathies: Weighing the Risks and Benefits

Inherited ion channelopathies have come to the forefront as a significant cause of sudden cardiac death (SCD) in pediatric patients with structurally normal hearts. Implantable cardioverter-defibrillator (ICD) placement can be a life-saving primary preventative therapy, but because of actors inherent in the pediatric population, careful thought must be given to the specific indications for placement in each patient. The most common inherited ion channelopathies are long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia. All have the potential to cause SCD. However, thanks to current research, more is now known about the range of phenotypes present within each disorder and also the benefits that medical therapy can provide. Risk stratification can allow clinicians to best predict which patients may most benefit from a primary preventative ICD while at the same time avoid placement in the larger group who may remain asymptomatic with the aid of medical therapy or even simply observation.

Decreased inappropriate shocks with new generation ICDs in children and patients with congenital heart disease

OBJECTIVE

Inappropriate implantable cardioverter defibrillator (ICD) shocks in children and patients with congenital heart disease (CHD) remain a major complication of device therapy, occurring in as many as 50% of children with ICDs. New generation devices include algorithms designed to minimize inappropriate shocks. This study aimed to evaluate the effect of new generation ICDs on the incidence of inappropriate shocks in the pediatric and CHD population.

DESIGN

Retrospective study of patients with CHD or under age 25 receiving ICDs between 2000 and 2015. New generation ICDs were defined as those with Medtronic "SmartShock" algorithms.

RESULTS

Two hundred eight devices were implanted in 146 patients. Rates of inappropriate shocks were similar between diagnoses (P = .71). The rate of inappropriate shock was 15% over median 5.8 years follow-up. In the 36 patients (25%) with new generation ICDs, the rate of inappropriate shock was 6.3% over 4 years. Comparing old to new generation ICDs, freedom from first inappropriate shock was 90.6% versus 97.1% at 1 year and 80.4% versus 97.1% at 3 years (P = .01). Lead fracture was associated with having inappropriate shock (hazard ratio 8.5, P < .0001), and there was no significant difference between the device groups when lead fractures were excluded. Clinical actions were taken in 69% of patients after initial inappropriate shock (such as medication or program change, system revision, or explant). When an action was taken, subsequent inappropriate shock was reduced (5.3% vs 49.2% at 1 year; P = .002).

CONCLUSIONS

Pediatric and CHD patients are experiencing reduced inappropriate shocks with new generation ICD systems, though reduced lead fracture may account for this improvement. Clinical interventions after inappropriate shock favorably impact the subsequent rate of shocks once an inappropriate shock occurs.

Inappropriate ICD Shocks in Pediatric and Congenital Heart Disease Patients

Although implantable cardioverter-defibrillators (ICDs) have proven to be life-saving devices, there are frequent complications associated with their use, especially in the pediatric and congenital heart disease populations. Inappropriate shocks are a particularly frequent complication in these groups. This review discusses the causes and implications of inappropriate ICD shocks, and presents potential interventions that may assist in safely reducing the rates of inappropriate shocks in pediatric and congenital heart disease patients with ICDs.

An Overview of Diagnosis and Management Strategies for Long QT Syndrome

Significant clinical, research, genetic, and therapeutic advances in the diagnosis and management of long QT syndrome (LQTS) have made the treatment of this channelopathy one of the most exciting and enlightening bench-to-bed success stories in the field of cardiology. Cascade screening identifies affected family members, and pre-symptomatic therapy saves lives. Here, we present a case of LQTS in a child and a review of the diagnostic and treatment strategies that have been introduced to date in the modern era.

Sudden Cardiac Death in Adult Congenital Heart Disease

Sudden death of presumed arrhythmic etiology is a leading cause of mortality in adults with congenital heart disease. Anticipated benefits of the implantable cardioverter-defibrillator (ICD) must be weighed against high complication rates. Without robust evidence from randomized trials, caregivers face difficult decisions in selecting appropriate candidates. Although secondary prevention indications are often clear-cut, risk stratification for primary prevention ICDs is more challenging. Factors associated with sudden death in patients with tetralogy of Fallot are reasonably consistent across studies. In contrast, identification of high-risk patients with systemic right ventricles or univentricular hearts remains controversial.