Recovery of echocardiographic function in children with idiopathic dilated cardiomyopathy: results from the pediatric cardiomyopathy registry

Pediatric dilated cardiomyopathy: a review of current clinical approaches and pathogenesis

Pediatric dilated cardiomyopathy (DCM) is a rare, yet life-threatening cardiovascular condition characterized by systolic dysfunction with biventricular dilatation and reduced myocardial contractility. Therapeutic options are limited with nearly 40% of children undergoing heart transplant or death within 2 years of diagnosis. Pediatric patients are currently diagnosed based on correlating the clinical picture with echocardiographic findings. Patient age, etiology of disease, and parameters of cardiac function significantly impact prognosis. Treatments for pediatric DCM aim to ameliorate symptoms, reduce progression of disease, and prevent life-threatening arrhythmias. Many therapeutic agents with known efficacy in adults lack the same evidence in children. Unlike adult DCM, the pathogenesis of pediatric DCM is not well understood as approximately two thirds of cases are classified as idiopathic disease. Children experience unique gene expression changes and molecular pathway activation in response to DCM. Studies have pointed to a significant genetic component in pediatric DCM, with variants in genes related to sarcomere and cytoskeleton structure implicated. In this regard, pediatric DCM can be considered pediatric manifestations of inherited cardiomyopathy syndromes. Yet exciting recent studies in infantile DCM suggest that this subset has a distinct etiology involving defective postnatal cardiac maturation, such as the failure of programmed centrosome breakdown in cardiomyocytes. Improved knowledge of pathogenesis is central to developing child-specific treatment approaches. This review aims to discuss the established biological pathogenesis of pediatric DCM, current clinical guidelines, and promising therapeutic avenues, highlighting differences from adult disease. The overarching goal is to unravel the complexities surrounding this condition to facilitate the advancement of novel therapeutic interventions and improve prognosis and overall quality of life for pediatric patients affected by DCM.

A Review of Pediatric Cardiomyopathy

Though pediatric cardiomyopathy is rare in children, there is significant associated morbidity and mortality. Etiology varies from inborn errors of metabolism to familial genetic mutations and myocyte injury. Major classes include dilated, hypertrophic, restrictive, and non-compaction. Diagnosis generally involves a combination of clinical history and echocardiography. The use of cross-sectional imaging is gaining popularity. Management varies between subtype and may involve a combination of medical and surgical interventions depending on clinical status.

The outcome of genetic and non-genetic pediatric cardiomyopathies

BACKGROUND

Pediatric cardiomyopathies (CMP) can be familial or idiopathic with increasing detection of genetic mutations. The study is a retrospective single-center review of cardiomyopathy patients from January 2011 to May 2020. Results of the genetic study, as well as the outcome, were reported. Patients were divided according to the type of CMP, age of presentation, and EF at presentation. Univariate and multivariate analysis and ROC and survival curves were done.

RESULTS

We reported 229 patients under 14 years of age with a diagnosis of cardiomyopathy, most commonly DCM (160 patients (70%)) followed by HCM (26.2%). 52% presented at 6 months of age or less and 119 (52%) required ICU admission at presentation. The genetic and or metabolic disorder was confirmed in 21.4% of patients, most commonly VLCAD defect (16, 7%) and ELAC2 gene defect (10, 4.4%). During the disease course, 88 patients (38.4%) died (48 with DCM, 39 with HCM, and 1 with RCM). An EF of 20% or less at presentation and presentation at 6 months of age or less carries a risk for mortality in patients with DCM and HCM, respectively (RR 3.88 and 2.06 and OR of 11.09 and 4.35, respectively). Death was more common among HCM patients especially patients with positive genetic abnormality compared with patients with DCM.

CONCLUSIONS

The mortality for CMP in children reaches up to 40%, (30% in DCM and 65% in HCM patients). Mortality was higher in those with HCM, DCM with EF of 20% or less, and HCM presented at 6 months of age or less. Whole-exome and/or whole-genome sequencing is advised for all patients of CMP and at-risk family members.

Progressive Left Ventricular Remodeling for Predicting Mortality in Children With Dilated Cardiomyopathy: The Pediatric Cardiomyopathy Registry

BACKGROUND

Pediatric dilated cardiomyopathy often leads to death or cardiac transplantation. We sought to determine whether changes in left ventricular (LV) end-diastolic dimension (LVEDD), LV end-diastolic posterior wall thickness, and LV fractional shortening (LVFS) over time may help predict adverse outcomes.

METHODS AND RESULTS

We studied children up to 18 years old with dilated cardiomyopathy, enrolled between 1990 and 2009 in the Pediatric Cardiomyopathy Registry. Changes in LVFS, LVEDD, LV end-diastolic posterior wall thickness, and the LV end-diastolic posterior wall thickness:LVEDD ratio between baseline and follow-up echocardiograms acquired ≈1 year after diagnosis were determined for children who, at the 1-year follow-up had died, received a heart transplant, or were alive and transplant-free. Within 1 year after diagnosis, 40 (5.0%) of the 794 eligible children had died, 117 (14.7%) had undergone cardiac transplantation, and 585 (73.7%) had survived without transplantation. At diagnosis, survivors had higher median LVFS and lower median LVEDD Z scores. Median LVFS and LVEDD Z scores improved among survivors (Z score changes of +2.6 and -1.1, respectively) but remained stable or worsened in the other 2 groups. The LV end-diastolic posterior wall thickness:LVEDD ratio increased in survivors only, suggesting beneficial reverse LV remodeling. The risk for death or cardiac transplantation up to 7 years later was lower when LVFS was improved at 1 year (hazard ratio [HR], 0.83; P=0.004) but was higher in those with progressive LV dilation (HR, 1.45; P<0.001).

CONCLUSIONS

Progressive deterioration in LV contractile function and increasing LV dilation are associated with both early and continuing mortality in children with dilated cardiomyopathy. Serial echocardiographic monitoring of these children is therefore indicated.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT00005391.

Inherited Arrhythmias in the Pediatric Population: An Updated Overview

Pediatric cardiomyopathies (CMs) and electrical diseases constitute a heterogeneous spectrum of disorders distinguished by structural and electrical abnormalities in the heart muscle, attributed to a genetic variant. They rank among the main causes of morbidity and mortality in the pediatric population, with an annual incidence of 1.1-1.5 per 100,000 in children under the age of 18. The most common conditions are dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Despite great enthusiasm for research in this field, studies in this population are still limited, and the management and treatment often follow adult recommendations, which have significantly more data on treatment benefits. Although adult and pediatric cardiac diseases share similar morphological and clinical manifestations, their outcomes significantly differ. This review summarizes the latest evidence on genetics, clinical characteristics, management, and updated outcomes of primary pediatric CMs and electrical diseases, including DCM, HCM, arrhythmogenic right ventricular cardiomyopathy (ARVC), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS), and short QT syndrome (SQTS).

Research Gaps in Pediatric Heart Failure: Defining the Gaps and Then Closing Them Over the Next Decade

Given the numerous opportunities and the wide knowledge gaps in pediatric heart failure, an international group of pediatric heart failure experts with diverse backgrounds were invited and tasked with identifying research gaps in each pediatric heart failure domain that scientists and funding agencies need to focus on over the next decade.

Heart Failure with Recovered Ejection Fraction in Patients with Vinculin Loss-of-function Variants

Predictors of myocardial recovery in heart failure (HF) are poorly understood. We explored if vinculin (VCL) variants are associated with myocardial recovery in dilated cardiomyopathy (DCM). Six infants with DCM with a VCL loss-of-function (LOF) variant were identified. Median age at diagnosis was 2 months, median LV ejection fraction was 24%, and median LV end-diastolic diameter z-score was 10.8. All patients received HF medications. Five patients (83%) showed normalization of LV function at a median age of 2.7 years. One patient progressed to end-stage HF requiring heart transplant. This case series identified a unique phenotype of HF with reduced ejection fraction at presentation that evolved to HF with recovered EF in over 80% of infant DCM cases with LOF VCL variants. These findings have prognostic implications for counseling and management of VCL-associated DCM and highlight a possible genetic basis for HF with recovered ejection fraction.

Treatment Strategies for Cardiomyopathy in Children: A Scientific Statement From the American Heart Association

This scientific statement from the American Heart Association focuses on treatment strategies and modalities for cardiomyopathy (heart muscle disease) in children and serves as a companion scientific statement for the recent statement on the classification and diagnosis of cardiomyopathy in children. We propose that the foundation of treatment of pediatric cardiomyopathies is based on these principles applied as personalized therapy for children with cardiomyopathy: (1) identification of the specific cardiac pathophysiology; (2) determination of the root cause of the cardiomyopathy so that, if applicable, cause-specific treatment can occur (precision medicine); and (3) application of therapies based on the associated clinical milieu of the patient. These clinical milieus include patients at risk for developing cardiomyopathy (cardiomyopathy phenotype negative), asymptomatic patients with cardiomyopathy (phenotype positive), patients with symptomatic cardiomyopathy, and patients with end-stage cardiomyopathy. This scientific statement focuses primarily on the most frequent phenotypes, dilated and hypertrophic, that occur in children. Other less frequent cardiomyopathies, including left ventricular noncompaction, restrictive cardiomyopathy, and arrhythmogenic cardiomyopathy, are discussed in less detail. Suggestions are based on previous clinical and investigational experience, extrapolating therapies for cardiomyopathies in adults to children and noting the problems and challenges that have arisen in this experience. These likely underscore the increasingly apparent differences in pathogenesis and even pathophysiology in childhood cardiomyopathies compared with adult disease. These differences will likely affect the utility of some adult therapy strategies. Therefore, special emphasis has been placed on cause-specific therapies in children for prevention and attenuation of their cardiomyopathy in addition to symptomatic treatments. Current investigational strategies and treatments not in wide clinical practice, including future direction for investigational management strategies, trial designs, and collaborative networks, are also discussed because they have the potential to further refine and improve the health and outcomes of children with cardiomyopathy in the future.

Cardiomyopathies in children: An overview

Paediatric cardiomyopathies form a heterogeneous group of disorders characterized by structural and electrical abnormalities of the heart muscle, commonly due to a gene variant of the myocardial cell structure. Mostly inherited as a dominant or occasionally recessive trait, they might be part of a syndromic disorder of underlying metabolic or neuromuscular defects or combine early developing extracardiac abnormalities (i.e., Naxos disease). The annual incidence of 1 per 100,000 children appears higher during the first two years of life. Dilated and hypertrophic cardiomyopathy phenotypes share an incidence of 60% and 25%, respectively. Arrhythmogenic right ventricular cardiomyopathy (ARVC), restrictive cardiomyopathy, and left ventricular noncompaction are less commonly diagnosed. Adverse events such as severe heart failure, heart transplantation, or death usually appear early after the initial presentation. In ARVC patients, high-intensity aerobic exercise has been associated with worse clinical outcomes and increased penetrance in at-risk genotype-positive relatives. Acute myocarditis in children has an incidence of 1.4-2.1 cases/per 100,000 children per year, with a 6-14% mortality rate during the acute phase. A genetic defect is considered responsible for the progression to dilated cardiomyopathy phenotype. Similarly, a dilated or arrhythmogenic cardiomyopathy phenotype might emerge with an episode of acute myocarditis in childhood or adolescence. This review provides an overview of childhood cardiomyopathies focusing on clinical presentation, outcome, and pathology.

Exploring the Possible Impact of Echocardiographic Diastolic Function Parameters on Outcome in Paediatric Dilated Cardiomyopathy

Diastolic dysfunction is an important determinant for prognosis and survival in several paediatric heart diseases. We aimed to explore its possible impact on outcome in children with dilated cardiomyopathy. From 2006 to 2016, children less than 18 years old with dilated cardiomyopathy were retrospectively enrolled. Echocardiographic diastolic function parameters and child outcomes were analysed. Of 43 children aged 0.2 to 16.1 years old referred with dilated cardiomyopathy, 8 patients required cardiac transplant or mechanical assist devices (18%), 24 had persistently abnormal left ventricular function and/or dilatation (56%) and 11 patients recovered (26%). There was no significant difference in mitral velocities on Tissue Doppler Imaging, mitral valve inflow velocities, isovolumic relaxation time, left atrial area z-score and mitral lateral E/e' ratios between patients with recovery and patients with disease progression or persistently abnormal ventricular function and/or dilation. This is the first study on childhood dilated cardiomyopathy to address individual echocardiographic diastolic function parameters and their association to recovery. In this study, echocardiographic parameters for diastolic function did not predict recovery.

Pediatric and adult dilated cardiomyopathy are distinguished by distinct biomarker profiles

BACKGROUND

Emerging evidence suggests that pediatric and adult dilated cardiomyopathy (DCM) represent distinct diseases. Few diagnostic tools exist for pediatric cardiologists to assess clinical status and prognosis. We hypothesized that pediatric DCM would have a unique biomarker profile compared to adult DCM and controls.

METHODS

We utilized a DNA aptamer array (SOMAScan) to compare biomarker profiles between pediatric and adult DCM. We simultaneously measured 1310 plasma proteins and peptides from 39 healthy children (mean age 3 years, interquartile range (IQR) 1-14), 39 ambulatory subjects with pediatric DCM (mean age 2.7 years, IQR 1-13), and 40 ambulatory adults with DCM (mean age 53 years, IQR 46-63).

RESULTS

Pediatric and adult DCM patients displayed distinct biomarker profiles, despite similar clinical characteristics. We identified 20 plasma peptides and proteins that were increased in pediatric DCM compared to age- and sex-matched controls. Unbiased multidimensionality reduction analysis suggested previously unrecognized heterogeneity among pediatric DCM subjects. Biomarker profile analysis identified four subgroups of pediatric DCM with distinguishing clinical characteristics.

CONCLUSIONS

These findings support the emerging concept that pediatric and adult DCM are distinct disease entities, signify the need to develop pediatric-specific biomarkers for disease prognostication, and challenge the paradigm that pediatric DCM should be viewed as a single disease.

IMPACT

Pediatric and adult DCM patients displayed distinct biomarker profiles, despite similar clinical characteristics and outcomes. Our findings suggest that pediatric DCM may be a heterogeneous disease with various sub-phenotypes, including differing biomarker profiles and clinical findings. These data provide prerequisite information for future prospective studies that validate the identified pediatric DCM biomarkers, address their diagnostic accuracy and prognostic significance, and explore the full extent of heterogeneity amongst pediatric DCM patients.

Clinical Profile and Risk Factors for Cardiac Death in Pediatric Patients With Primary Dilated Cardiomyopathy at a Tertiary Medical Center in China

AIM

We sought to identify the clinical characteristics and risk factors for cardiac mortality in pediatric patients with primary dilated cardiomyopathy (DCM) in China.

METHODS

A total of 138 pediatric patients who were consecutively diagnosed with primary DCM from January 2011 to December 2020 were included. We assessed patients' clinical symptoms and performed laboratory examinations, electrocardiography, and echocardiography.

RESULTS

Of these patients, 79 (57%) had severe systolic dysfunction (left ventricular ejection fraction of < 30%), 79 (57.2%) developed DCM before 12 months of age, 62 (45%) were male, 121 (87.7%) presented with advanced heart failure (cardiac functional class III/IV), and 54 (39.1%) presented with arrhythmia. At a median follow-up of 12 months, the overall cardiac mortality rate was 33%, and 40 of 46 deaths occurred within 6 months following DCM diagnosis. A multivariate Cox regression analysis identified several independent cardiac death predictors, including an age of 12 months to 5 years [hazard ratio (HR) 2.799; 95% confidence interval (CI) 1.160-6.758; P = 0.022] or 10-15 years (HR 3.617; 95% CI 1.336-9.788; P = 0.011) at diagnosis, an elevated serum alanine aminotransferase (ALT) concentration (≥ 51.5 U/L) (HR 2.219; 95% CI 1.06-4.574; P = 0.031), and use of mechanical ventilation (HR 4.223; 95% CI 1.763-10.114; P = 0.001).

CONCLUSION

The mortality rate of primary DCM without transplantation is high. Age, an elevated serum ALT concentration, and the need for mechanical ventilation predict mortality in patients with primary DCM, providing new insights into DCM risk stratification.

Extended recovery of cardiac function after severe infantile cardiomyopathy presentation of Barth syndrome

Cardiomyopathy is the most common presenting feature of Barth syndrome, often presenting in infancy with severe heart failure and cardiac dysfunction. Historically, affected infants commonly died early after presentation, sometimes before a diagnosis of Barth syndrome was made. With increases in awareness of Barth syndrome and in the care of infants with severe heart failure, survival of children with Barth syndrome and severe heart failure has improved. We describe our experience caring for five unrelated boys with Barth syndrome who presented with severe cardiomyopathy and heart failure prior to age 2 who have had marked improvement with long‐term response to medical heart failure therapy.

Cardiac response to adrenergic stress differs by sex and across the lifespan

The aging heart is well-characterized by a diminished responsiveness to adrenergic activation. However, the precise mechanisms by which age and sex impact adrenergic-mediated cardiac function remain poorly described. In the current investigation, we compared the cardiac response to adrenergic stress to gain mechanistic understanding of how the response to an adrenergic challenge differs by sex and age. Juvenile (4 weeks), adult (4-6 months), and aged (18-20 months) male and female mice were treated with the β-agonist isoproterenol (ISO) for 1 week. ISO-induced morphometric changes were age- and sex-dependent as juvenile and adult mice of both sexes had higher left ventricle weights while aged mice did not increase cardiac mass. Adults increased myocyte cell size and deposited fibrotic matrix in response to ISO, while juvenile and aged animals did not show evidence of hypertrophy or fibrosis. Juvenile females and adults underwent expected changes in systolic function with higher heart rate, ejection fraction, and fractional shortening. However, cardiac function in aged animals was not altered in response to ISO. Transcriptomic analysis identified significant differences in gene expression by age and sex, with few overlapping genes and pathways between groups. Fibrotic and adrenergic signaling pathways were upregulated in adult hearts. Juvenile hearts upregulated genes in the adrenergic pathway with few changes in fibrosis, while aged mice robustly upregulated fibrotic gene expression without changes in adrenergic genes. We suggest that the response to adrenergic stress significantly differs across the lifespan and by sex. Mechanistic definition of these age-related pathways by sex is critical for future research aimed at treating age-related cardiac adrenergic desensitization.

Differential Expression Profiles and Functional Prediction of Circular RNAs in Pediatric Dilated Cardiomyopathy

Circular RNAs (circRNAs) have emerged as essential regulators and biomarkers in various diseases. To assess the different expression levels of circRNAs in pediatric dilated cardiomyopathy (PDCM) and explore their biological and mechanistic significance, we used RNA microarrays to identify differentially expressed circRNAs between three children diagnosed with PDCM and three healthy age-matched volunteers. The biological function of circRNAs was assessed with a circRNA–microRNA (miRNA)–mRNA interaction network constructed from Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes. Differentially expressed circRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR) in 25 children with PDCM and 25 healthy volunteers. We identified 257 up-regulated (fold change ≤ 0.5, P < 0.05) and 899 down-regulated (fold change ≥2, P < 0.05) circRNAs in PDCM patients when compared to healthy volunteers. The qRT-PCR experiments confirmed has_circ_0067735 down-regulation (0.45-fold, P < 0.001), has_circ_0070186 up-regulation (2.82-fold, P < 0.001), and has_circ_0069972 down-regulation (0.50-fold, P < 0.05). A functional analysis of these differentially expressed circRNAs suggests that they are associated with hypertrophy, remodeling, fibrosis, and autoimmunity. CircRNAs have been implicated in PDCM through largely unknown mechanisms. Here we report differentially expressed circRNAs in PDCM patients that may illuminate the mechanistic roles in the etiology of PDCM that could serve as non-invasive diagnostic biomarkers.

Review of Insulin Resistance in Dilated Cardiomyopathy and Implications for the Pediatric Patient Short Title: Insulin Resistance DCM and Pediatrics

Energy metabolism in the heart is affected during states of dysfunction. Understanding how the heart utilizes substrates in cardiomyopathy may be key to the development of alternative treatment modalities. Myocardial insulin resistance has been proposed as a possible barrier to effective glucose metabolism in the heart. Extensive literature on the topic in adult individuals exists; however, review in the pediatric population is sparse. The pathophysiology of disease in children and adolescents is unique. The aim of this paper is to review the current knowledge on insulin resistance in dilated cardiomyopathy while also filling the gap when considering care in the pediatric population.

Long-Term Outcomes and Prognosticators of Pediatric Primary Dilated Cardiomyopathy in an Asian Cohort

Background: Dilated cardiomyopathy (DCM) is the most common childhood cardiomyopathy. The epidemiological profiles and prognosticators of clinical outcomes in Asian populations are not well elucidated. Methods: Data of 104 children aged <18 years with a diagnosis of primary DCM from January 1990 to December 2019 in our institutional database were retrospectively investigated. Relevant demographic, echocardiographic, and clinical variables were recorded for analysis. A P <0.05 was considered statistically significant. Results: The median age at diagnosis was 1.4 years (interquartile range = 0.3-9.1 years), and 52.9% were males. During a median follow-up duration of 4.8 years, 48 patients (46.2%) were placed on the transplantation waitlist, and 52.1% of them eventually received heart transplants. An exceptionally high overall waitlist mortality rate was noted (27.1%), which was even higher (43.5%) if the diagnostic age was <3 years. The 1-, 5-, and 10-year transplant-free were 61.1, 48.0, and 42.8%. Age at diagnosis >3 years and severe mitral regurgitation at initial diagnosis were independent risk factors for death or transplantation (hazard ratios = 2.93 and 3.31, respectively; for both, P <0.001). In total, 11 patients (10.6%) experienced ventricular function recovery after a median follow-up of 2.5 (interquartile range = 1.65-5) years. Younger age at diagnosis was associated a higher probability of ventricular function recovery. Conclusions: Despite donor shortage for heart transplantation and subsequently high waitlist mortality, our data from an Asian cohort indicated that transplant-free long-term survival was comparable with that noted in reports from Western populations. Although younger patients had exceptionally higher waitlist mortality, lower diagnostic age was associated with better long-term survival and higher likelihood of ventricular function recovery.

Development of Cardiac Events and Functional Recovery Prediction Models for Pediatric Dilated Cardiomyopathy

Background: Since both the risk of death and the probability of spontaneous functional recovery (FR) coexist in association with pediatric dilated cardiomyopathy (DCMP), management should be based on individualized outcome predictions. Methods: A single-center retrospective review of 105 pediatric patients (age at presentation ≤ 18 years) with DCMP, managed between 1994 and 2017, was performed. Logistic regression was conducted to identify variables associated with FR and cardiac events (CEs), i.e., death or heart transplantation (HTPL), within 2 years after initial presentation. Two outcome prediction models were formulated using these variables. Results: Twenty-six (24.8%) and 51 patients (48.6%) experienced FR and CE, respectively, within 2 years after initial presentation. Predictors of mortality without HTPL were earlier era at presentation (HR: 4.13; 95% CI: 1.88-9.06; p < 0.001) and significant TR (≥moderate; HR: 4.31; 95% CI: 1.26-14.77; p = 0.020) in multivariable Cox regression model. Predictors of FR were recent era (HR: 4.49; 95% CI: 1.40-14.44; p = 0.0012), younger age at initial presentation (HR: 0.98 per 1 month increase; 95% CI: 0.97-0.99, p < 0.001), post-myocarditis DCMP (HR: 4.29; 95% CI: 1.32-13.93; p = 0.015), and arrhythmia-mediated DCMP (HR: 26.88; 95% CI: 2.61-276.70; p = 0.006). Risk factors for CEs was idiopathic DCMP (HR: 2.95; 95% CI: 1.32-6.56, p = 0.008). The low-risk group who had higher probability of FR than CE in prediction model had a slightly higher overall survival rate (71.4 vs. 52.2% at 10 years after presentation; log-rank p = 0.09) and a significantly higher HTPL-free survival rate (67.5 vs. 24.9% at 10 years after presentation; log-rank p < 0.001) than the high-risk group. Conclusions: Prognostication and management strategies for pediatric DCMP may be enhanced by risk stratification using outcome prediction modeling.

Higher Serum Lysophosphatidic Acids Predict Left Ventricular Reverse Remodeling in Pediatric Dilated Cardiomyopathy

Background: The prognosis of pediatric dilated cardiomyopathy (PDCM) is highly variable, ranging from death to cardiac function recovery. Left ventricular reverse remodeling (LVRR) represents a favorable prognosis in PDCM. Disturbance of lipid metabolism is associated with the change of cardiac function, but no studies have examined lipidomics data and LVRR. Methods: Discovery analyses were based on 540 targeted lipids in an observational, prospective China-AOCC (An Integrative-Omics Study of Cardiomyopathy Patients for Diagnosis and Prognosis in China) study. The OPLS-DA and random forest (RF) analysis were used to screen the candidate lipids. Associations of the candidate lipids were examined in Cox proportional hazards regression models. Furthermore, we developed a risk score comprising the significant lipids, with each attributed a score of 1 when the concentration was above the median. All significant findings were replicated in a validation set of the China-AOCC study. Results: There were 59 patients in the discovery set and 24 patients in the validation set. LVRR was observed in 27 patients (32.5%). After adjusting for age, left ventricular ejection fraction (LVEF), and left ventricular end-diastolic dimension (LVEDD) z-score, lysophosphatidic acids (LysoPA) 16:0, LysoPA 18:2, LysoPA 18:1, and LysoPA 18:0 were significantly associated with LVRR in the discovery set, and hazard ratios (HRs) were 2.793 (95% CI, 1.545-5.048), 2.812 (95% CI, 1.542-5.128), 2.831 (95% CI, 1.555-5.154), and 2.782 (95% CI, 1.548-5.002), respectively. We developed a LysoPA score comprising the four LysoPA. When the LysoPA score reached 4, LVRR was more likely to be observed in both sets. The AUC increased with the addition of the LysoPA score to the LVEDD z-score (from 0.693 to 0.875 in the discovery set, from 0.708 to 0.854 in the validation set) for prediction of LVRR. Conclusions: Serum LysoPA can predict LVRR in PDCM patients. When the LysoPA score was combined with the LVEDD z-score, it may help in ascertaining the prognosis and monitoring effects of anti-heart failure pharmacotherapy.

Overview of Cardiomyopathies in Childhood

Paediatric cardiomyopathies are a heterogenous group of rare disorders, characterised by mechanical and electrical abnormalities of the heart muscle. The overall annual incidence of childhood cardiomyopathies is estimated at about 1 per 100,000 children and is significantly higher during the first 2 years of life. Dilated cardiomyopathies account for approximately half of the cases. Hypertrophic cardiomyopathies form the second largest group, followed by the less common left ventricular non-compaction and restrictive phenotypes. Infectious, metabolic, genetic, and syndromic conditions account for the majority of cases. Congestive heart failure is the typical manifestation in children with dilated cardiomyopathy, whereas presenting symptoms are more variable in other phenotypes. The natural history is largely influenced by the type of cardiomyopathy and its underlying aetiology. Results from a national population-based study revealed 10-year transplant-free survival rates of 80, 62, and 48% for hypertrophic, dilated and left ventricular non-compaction cardiomyopathies, respectively. Long-term survival rates of children with a restrictive phenotype have largely been obscured by early listing for heart transplantation. In general, the majority of adverse events, including death and heart transplantation, occur during the first 2 years after the initial presentation. This review provides an overview of childhood cardiomyopathies with a focus on epidemiology, natural history, and outcomes.

Longitudinal Prediction of Transplant-Free Survival by Echocardiography in Pediatric Dilated Cardiomyopathy

BACKGROUND

The prognostic significance of serial echocardiography and its rate of change in children with dilated cardiomyopathy (DCM) is incompletely defined.

METHODS

We retrospectively analysed up to 4 serial echocardiograms. Associations between mortality/transplant and echocardiographic parameters over time and between outcomes and the rate of change of echocardiographic parameters were analysed. Estimation of patient-specific intercepts and slopes was done using linear regression models.

RESULTS

Fifty-seven DCM children were studied (50% male; median age, 0.6 year; average follow-up, 2.1 ± 2.4 years). The median time to transplant or death was 2.0 years. Increased left ventricular (LV) diastolic (LVEDD) and systolic (LVESD) dimensions and myocardial performance index (MPI) were associated with increased mortality and transplant risk. Increased LV ejection fraction, mitral E-deceleration time, right ventricular (RV) fractional area change, and tricuspid annular plane systolic excursion were associated with reduced mortality and transplant risk. Transplant/mortality likelihood increased by 41.6% and 19.8% for each unit increase in LVEDD and LVESD z scores, respectively (LVEDD: hazard ratio [HR], 1.416; 95% confidence interval [CI], 1.285-1.560; P < 0.001; LVESD: HR, 1.198; 95% CI, 1.147-1.251; P < 0.001). A higher monthly change in LVESD z score increased transplant/mortality likelihood by 85.6% (HR, 1.856; 95% CI, 1.572-2.191; P = 0.015). Greater changes in mitral E/e' (HR, 0.707; 95% CI, 0.636-0.786; P < 0.001) and RV MPI (HR, 0.412; 95% CI, 0.277-0.613; P < 0.001) were associated with reduced mortality and transplant risk.

CONCLUSIONS

LV and RV systolic and diastolic dimensions and function over time and their rate of change are associated with risk for transplant and mortality in childhood DCM. Serial changes in these parameters may be useful to predict clinical outcomes.

Important Considerations in Pediatric Heart Failure

PURPOSE OF REVIEW

The goal of this paper is to provide an overview of contemporary knowledge specific to the causes, management, and outcome of heart failure in children.

RECENT FINDINGS

While recently there have been subtle improvements in heart failure outcomes in children, these improvements lag significantly behind that of adults. There is a growing body of literature suggesting that pediatric heart failure is a unique disease process with age- and disease-specific myocardial adaptations. In addition, the heterogenous etiologies of heart failure in children contribute to differential response to therapies and challenge the ability to obtain meaningful results from prospective clinical trials. Consideration of novel clinical trial designs with achievable but clinically relevant endpoints and focused study of the mechanisms underlying pediatric heart failure secondary to cardiomyopathies and structural heart disease are essential if we hope to advance care and identify targeted and effective therapies.

Beyond genomics-technological advances improving the molecular characterization and precision treatment of heart failure

Dilated cardiomyopathy (DCM) is a major cause of heart failure and cardiovascular mortality. In the past 20 years, there has been an overwhelming focus on developing therapeutics that target common downstream disease pathways thought to be involved in all forms of heart failure independent of the initial etiology. While this strategy is effective at the population level, individual responses vary tremendously and only approximately one third of patients receive benefit from modern heart failure treatments. In this perspective, we propose that DCM should be considered as a collection of diseases with a common phenotype of left ventricular dilation and systolic dysfunction rather than a single disease entity, and that mechanism-based classification of disease subtypes will revolutionize our understanding and clinical approach towards DCM. We discuss how these efforts are central to realizing the potential of precision medicine and how they are empowered by the development of new tools that allow investigators to strategically employ genomic and transcriptomic information. Finally, we outline an investigational strategy to (1) define DCM at the patient level, (2) develop new tools to model and mechanistically dissect subtypes of human heart failure, and (3) harness these insights for the development of precision therapeutics.

Elevated Heart Rate and Survival in Children With Dilated Cardiomyopathy: A Multicenter Study From the Pediatric Cardiomyopathy Registry

Background In adults with heart failure, elevated heart rate is associated with lower survival. We determined whether an elevated heart rate was associated with an increased risk of death or heart transplant in children with dilated cardiomyopathy. Methods and Results The study is an analysis of the Pediatric Cardiomyopathy Registry and includes baseline data, annual follow-up, and censoring events (transplant or death) in 557 children (51% male, median age 1.8 years) with dilated cardiomyopathy diagnosed between 1994 and 2011. An elevated heart rate was defined as 2 or more SDs above the mean heart rate of children, adjusted for age. The primary outcomes were heart transplant and death. Heart rate was elevated in 192 children (34%), who were older (median age, 2.3 versus 0.9 years; P<0.001), more likely to have heart failure symptoms (83% versus 67%; P<0.001), had worse ventricular function (median fractional shortening z score, -9.7 versus -9.1; P=0.02), and were more often receiving anticongestive therapies (96% versus 86%; P<0.001) than were children with a normal heart rate. Controlling for age, ventricular function, and cardiac medications, an elevated heart rate was independently associated with death (adjusted hazard ratio [HR] 2.6; P<0.001) and with death or transplant (adjusted HR 1.5; P=0.01). Conclusions In children with dilated cardiomyopathy, elevated heart rate was associated with an increased risk of death and cardiac transplant. Further study is warranted into the association of elevated heart rate and disease severity in children with dilated cardiomyopathy and as a potential target of therapy.

The relationship between electrocardiographic data and mortality in children diagnosed with dilated cardiomyopathy

The mortality causes of patients followed up due to dilated cardiomyopathy (DCM) include complications related to heart failure, ventricular arrhythmia, and transplantation. This study aims to evaluate the electrocardiographic findings of patients diagnosed with dilated cardiomyopathy and determine its relationship with mortality. The electrocardiographic, clinical, and laboratory findings of patients diagnosed with dilated cardiomyopathy between January 1, 2012, and September 1, 2018, in our university's pediatric cardiology department were retrospectively evaluated. The electrocardiographic findings of surviving and exitus dilated cardiomyopathy patients were compared and their effect on mortality was investigated. Twelve of the total 85 patients diagnosed with dilated cardiomyopathy were deceased. According to the electrocardiographic findings of surviving and exitus patients, there was a statistically significant difference in terms of P maximum (Pmax), P dispersion (Pdis), QT dispersion (QTdis), QTc maximum (QTcmax), QTc dispersion (QTcdis), Tp-e maximum (Tp-emax), Tp-e dispersion (Tp-edis), and QRS time. Hypertrophy and ischemia findings of electrocardiography were also statistically significant. There was a statistically significant difference between the two groups according to the echocardiographic findings of left ventricular ejection fraction (LVEF), left ventricular shortening fraction (LVSF), left ventricular end-diastolic diameter (LVEDd), and left ventricular end-systolic diameter (LVESd) measurements. It is well known that children diagnosed with dilated cardiomyopathy are at greater risk of arrhythmia compared with normal children. Although previous studies have determined the relationship between mortality and a limited number of electrocardiographic findings, especially in adults, the relationship between electrocardiography findings of children diagnosed with DCM and mortality has not been investigated before in such detail, as in our study.Conclusion: In this study, the significant difference between the electrocardiographic data of deceased and surviving dilated cardiomyopathy patients suggests that electrocardiographic data should be evaluated in detail in order to determine the low and high risk of mortality in patients with dilated cardiomyopathy.What is Known:• Previous studies on the relationship between limited electrocardiography data of adult patients diagnosed with DCM and mortality have been determinedWhat is New:• ECG data has not been investigated in such detail in child DCM patients, as in our study.

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.

[Association of T-wave amplitude on electrocardiogram with left ventricular ejection fraction in children with dilated cardiomyopathy]

OBJECTIVE

To study the association of T-wave amplitude on electrocardiogram (ECG) with left ventricular ejection fraction (LVEF) in children with dilated cardiomyopathy.

METHODS

A retrospective analysis was performed for the clinical data of 44 children who were diagnosed with dilated cardiomyopathy from May 2009 to June 2018. According to LVEF, they were divided into two groups: LVEF ≥50% group (n=26) and LVEF <50% group (n=18). After treatment, 25 children were followed up for 3-42 months (mean 14±9 months). The Guangdong Zhongshan SR-1000A ECG Automatic Analyzer was used to obtain the 12-lead body surface ECG results in the supine position. T-wave amplitude on ECG was evaluated by software and manual measurement.

RESULTS

Compared with the LVEF ≥50% group, the LVEF <50% group had a significant reduction in the T-wave amplitude in leads II, V4, V5 and V6 (P<0.05). The increased-LVEF group (an increase in LVEF > 5% after treatment) had a significant increase in the T-wave amplitude in leads aVR, V5, and V6 after treatment (P<0.05), while the unchanged-LVEF group (an increase in LVEF ≤ 5% after treatment) had a significant reduction in the T-wave amplitude in lead aVR after treatment (P<0.05). The receiver operating characteristic curve analysis showed that the T-wave amplitude in leads II, V4, V5 and V6 had a certain value in predicting LVEF <50% in children with dilated cardiomyopathy (P<0.05). A combination of T-wave amplitude of ≤0.20 mV in lead II, ≤0.40 mV in lead V4, and ≤0.30 mV in leads V5 and V6 had a sensitivity of 88.2% and specificity of 76.0% in the predication of LVEF <50% in children with dilated cardiomyopathy.

CONCLUSIONS

T-wave amplitude on ECG can be used as the indexes for the evaluation of the left ventricular systolic function in children with dilated cardiomyopathy.

Emotional and behavioral problems in children with dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) in children is an important cause of severe heart failure and carries a poor prognosis. Adults with heart failure are at increased risk of anxiety and depression and such symptoms predict adverse clinical outcomes such as mortality. In children with DCM, studies examining these associations are scarce.

AIMS

We studied whether in children with DCM: (1) the level of emotional and behavioral problems was increased as compared to normative data, and (2) depressive and anxiety problems were associated with the combined risk of death or cardiac transplantation.

METHODS

To assess emotional and behavioral problems in children with DCM, parents of 68 children, aged 1.5-18 years (6.9±5.7 years), completed the Child Behavior Checklist.

RESULTS

Compared to normative data, more young children (1.5-5 years) with DCM had somatic complaints (24.3% vs. 8.0%; p < .001), but fewer had externalizing problems (5.4% vs. 17.0%; p = .049). Overall internalizing problems did not reach significance. Compared to normative data, more older children (6-18 years) showed internalizing problems (38.7% vs. 17.0%; p = .001), including depressive (29.0% vs. 8.0%; p < .001) and anxiety problems (19.4% vs. 8.0%; p = .023), and somatic complaints (29.0% vs. 8.0%; p < .001). Anxiety and depressive problems, corrected for heart failure severity, did not predict the risk of death or cardiac transplantation.

CONCLUSION

Children of 6 years and older showed more depressive and anxiety problems than the normative population. Moreover, in both age groups, somatic problems were common. No association with outcome could be demonstrated.

Prognostic significance of tissue Doppler imaging-derived myocardial performance index in pediatric patients with dilated cardiomyopathy

TDI-MPI has been shown to predict cardiovascular mortality in adults; there are a paucity of data on its use in children. We sought to determine the prognostic significance of TDI-MPI at time of DCM diagnosis in children. Patients aged ≤18 years diagnosed with DCM were included along with age- and sex-matched controls. Echo at diagnosis was analyzed to obtain standard measures of LV function, PW-MPI, and septal and LV free wall TDI-MPI. Survival analysis was used to assess the time to composite outcome of death, VAD, or transplant, stratified by TDI-MPI z-score. The study included 79 patients with DCM and 79 controls. During a median follow-up of 182 days (IQR 41-815 days), 16 underwent VAD placement, 21 underwent cardiac transplant, 6 died, and 36 had event-free survival. The median septal TDI-MPI for cases was 0.70 for patients with DCM vs 0.45 for controls (P < .001). Those with septal TDI-MPI z-scores ≥2 develop events significantly earlier than those with z-score <2 (P = .014). In multivariable analysis, TDI-MPI z-score ≥2 was significantly associated with poor outcomes (HR 2.12, 95% CI 1.06-4.23). TDI-MPI can be reliably performed in pediatric patients with DCM. A TDI-MPI z-score ≥2 at diagnosis may be associated with earlier poor outcome. Further studies evaluating the use of TDI-MPI in longitudinal follow-up of patients with DCM may be helpful in refining its clinical use.

Left Ventricular Layer-Specific Myocardial Strains in Children with Recovered Primary Dilated Cardiomyopathy: What Lies Beneath the Iceberg?

We aimed to detect residual cardiac dysfunction-if any-in children with recovered primary dilated cardiomyopathy (DCM) by using the left ventricular (LV) layer-specific myocardial strains. Fifty children with recovered primary DCM both clinically and echocardiographically were included as the patient group. Fifty healthy children of matched age and sex served as the control group. Echocardiographic evaluation was performed for all included children in the form of conventional echocardiography, tissue Doppler imaging (TDI), two-dimensional speckle tracking echocardiography (2D-STE), and LV layer-specific myocardial strain. Both LV systolic and diastolic functions measured by conventional echocardiography were similar in children with recovered DCM and the control group. There was a significant reduction in LV systolic and diastolic functions measured by TDI in the patient group. Moreover, there was a significant reduction of LV global longitudinal systolic strain (GLSS) by 2D-STE in children with recovered DCM. Interestingly, there was a significant reduction of LV layer-specific myocardial strain from endocardium to epicardium in children with recovered DCM compared to the healthy control. There was a significant positive correlation between different layer-specific myocardial strains and LV GLSS, LV ejection fraction, and LV peak systolic velocity. Left ventricular layer-specific myocardial strain can be a promising tool for early identifications of LV dysfunction in children with DCM. Subtle cardiac dysfunction is present in patients with recovered DCM, so long-term follow-up is recommended in these patients.

Does Repeated Measurement of a 6-Min Walk Test Contribute to Risk Prediction in Children with Dilated Cardiomyopathy?

A single 6-min walk test (6MWT) can be used to identify children with dilated cardiomyopathy (DCM) with a high risk of death or heart transplantation. To determine if repeated 6MWT has added value in addition to a single 6MWT in predicting death or heart transplantation in children with DCM. Prospective multicenter cohort study including ambulatory DCM patients ≥ 6 years. A 6MWT was performed 1 to 4 times per year. The distance walked was expressed as percentage of predicted (6MWD%). We compared the temporal evolution of 6MWD% in patients with and without the study endpoint (SE: all-cause death or heart transplantation), using a linear mixed effects model. In 57 patients, we obtained a median of 4 (IQR 2-6) 6MWTs per patient during a median of 3.0 years of observation (IQR 1.5-5.1). Fourteen patients reached a SE (3 deaths, 11 heart transplantations). At any time during follow-up, the average estimate of 6MWD% was significantly lower in patients with a SE compared to patients without a SE. In both patients groups, 6MWD% remained constant over time. An absolute 1% lower 6MWD% was associated with an 11% higher risk (hazard) of the SE (HR 0.90, 95% CI 0.86-0.95 p < 0.001). Children with DCM who died or underwent heart transplantation had systematically reduced 6MWD%. The performance of all patients was stable over time, so repeated measurement of 6MWT within this time frame had little added value over a single test.

Cardiac Biomarkers in Pediatric Cardiomyopathy: Study Design and Recruitment Results from the Pediatric Cardiomyopathy Registry

Background

Cardiomyopathies are a rare cause of pediatric heart disease, but they are one of the leading causes of heart failure admissions, sudden death, and need for heart transplant in childhood. Reports from the Pediatric Cardiomyopathy Registry (PCMR) have shown that almost 40% of children presenting with symptomatic cardiomyopathy either die or undergo heart transplant within 2 years of presentation. Little is known regarding circulating biomarkers as predictors of outcome in pediatric cardiomyopathy.

Study Design

The Cardiac Biomarkers in Pediatric Cardiomyopathy (PCM Biomarkers) study is a multi-center prospective study conducted by the PCMR investigators to identify serum biomarkers for predicting outcome in children with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM). Patients less than 21 years of age with either DCM or HCM were eligible. Those with DCM were enrolled into cohorts based on time from cardiomyopathy diagnosis: categorized as new onset or chronic. Clinical endpoints included sudden death and progressive heart failure.

Results

There were 288 children diagnosed at a mean age of 7.2±6.3 years who enrolled in the PCM Biomarkers Study at a median time from diagnosis to enrollment of 1.9 years. There were 80 children enrolled in the new onset DCM cohort, defined as diagnosis at or 12 months prior to enrollment. The median age at diagnosis for the new onset DCM was 1.7 years and median time from diagnosis to enrollment was 0.1 years. There were 141 children enrolled with either chronic DCM or chronic HCM, defined as children ≥2 years from diagnosis to enrollment. Among children with chronic cardiomyopathy, median age at diagnosis was 3.4 years and median time from diagnosis to enrollment was 4.8 years.

Conclusion

The PCM Biomarkers study is evaluating the predictive value of serum biomarkers to aid in the prognosis and management of children with DCM and HCM. The results will provide valuable information where data are lacking in children.

Clinical Trial Registration NCT01873976

https://clinicaltrials.gov/ct2/show/NCT01873976?term=PCM+Biomarker&rank=1.

Disparate Remodeling of the Extracellular Matrix and Proteoglycans in Failing Pediatric Versus Adult Hearts

Background

Dilated cardiomyopathy (DCM) is a common cause of heart failure in adult and pediatric patients, but the underlying mechanism may vary in adults and children, with few studies conducted to date. The objective of the present study was to determine whether differential remodeling of the extracellular matrix contributes to the differences between pediatric and adult DCM hearts.

Methods and Results

Explanted hearts were procured from adult (age, 46–61 years) and pediatric (age, 2–8) patients with DCM‐related heart failure and nonfailing control hearts. Fibrillar and nonfibrillar extracellular matrix (proteoglycans, glycosaminoglycans, glycoprotein), their regulatory enzymes (matrix metalloproteinases, disintegrin and metalloproteinases, and disintegrin and metalloproteinases with a thrombospondin domain), and their inhibitors (tissue inhibitor of metalloproteinases) were assessed. Pediatric DCM hearts exhibited less fibrosis compared with adult DCMs. Total glycosaminoglycans increased similarly in both DCM groups but exhibited a significantly lower affinity for transforming growth factor‐β in adult DCMs versus pediatric DCMs, resulting in increased bioavailability of transforming growth factor‐β1 and a significantly higher activity of the Smad2/3 pathway in adult DCMs. Glycosylated biglycan and versican, and cleaved thrombospondin‐1 increased in both DCMs. Protein expression of disintegrin and metalloproteinases with thrombospondin domains (‐1, ‐2, ‐4, ‐7) and disintegrin and metalloproteinases (‐12, ‐15, ‐17, ‐19) were altered differently in pediatric and adult control and failing hearts. Total matrix metalloproteinase activity increased in both DCMs. Tissue inhibitor of metalloproteinase levels were altered similarly with heart failure in both age groups, and only tissue inhibitor of metalloproteinase 3 decreased in both DCM groups.

Conclusions

Differential remodeling of glycosaminoglycans in pediatric DCMs versus adult DCMs could underlie the enhanced activation of the transforming growth factor‐β pathway, leading to more fibrosis in adult DCM hearts. The distinct remodeling of the fibrillar and nonfibrillar extracellular matrix between pediatric and adult DCM hearts highlights a distinct pathophysiological basis for these cohorts.

Low mutation rate in the TTN gene in paediatric patients with dilated cardiomyopathy - a pilot study

Idiopathic dilated cardiomyopathy (DCM) is a common cardiomyopathy with the prevalence of 1:250, and at least one-third of all the cases are inherited. Mutations in the TTN gene are considered as the most frequent cause of inherited DCM and cover 10–30% of the cases. The studies were mainly focused on the adult or mixed age group of patients with DCM. The mutation rate in the TTN gene, the characteristics of manifestations and their prognostic significance in childhood have not been studied. To determine TTN mutation rate in children with DCM and the relevance of including this gene in the DNA diagnostic protocol for paediatric DCM, complete clinical and instrumental examination of 36 DCM patients (up to 18 years) with the manifestation of the disease was conducted in specialised cardiology centres. Molecular genetic testing included sequencing of coding and adjacent regulatory regions of the major cardiac TTN isoform N2BA using IonTorrent ™ semiconductor sequencing (for 25 isolated cases) and trio whole exome sequencing (trio WES)on the Illumina platform (for 11 family cases). Our pilot group included 36 probands with DCM diagnosis first established on the basis of the generally accepted criteria at the age of 5 days to 18 years(average age: 6.5 years). The sex ratio (M:F) was 23: 8. There were 25 sporadic DCM cases and 11 cases of familial DCM (at least one of the parents and/or siblings were also diagnosed with DCM). The only likely pathogenic truncating variant p.Arg33703*in the TTN gene (TTNtv) was found in a 16-year-oldmale proband out of 36 (3%). Apparently, TTN-dependent forms of DCMs manifest later at a young (but older than 18 years) or more mature age, and TTN gene cannot be considered as the first-line genetic testing for DCM in the paediatric group, despite several studies have reported a generally high mutation rate in this gene with DCM. Further research is needed to compare the representation of mutations in the TTN gene in different age groups of DCM patients.

Wearable cardioverter-defibrillators in pediatric cardiomyopathy: A cost-utility analysis

BACKGROUND

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy in children. Patients with severe cardiac dysfunction are thought to be at risk of sudden cardiac arrest (SCA). After diagnosis, a period of medical optimization is recommended before permanent implantable cardioverter-defibrillator (ICD) implantation. Wearable cardioverter-defibrillators (WCDs) provide an option for arrhythmia protection as an outpatient during this optimization.

OBJECTIVE

The purpose of this study was to determine the strategy that optimizes cost and survival during medical optimization of a patient with DCM before ICD placement.

METHODS

A Markov state transition model was constructed for the 3 clinical approaches to compare costs, clinical outcomes, and quality of life: (1) "Inpatient," (2) "Home-WCD," and (3) "Home-No WCD." Transitional probabilities, costs, and utility metrics were extracted from the existing literature. Cost-effectiveness was assessed comparing each paradigm's incremental cost-effectiveness ratio against a societal willingness-to-pay threshold of $50,000 per quality-adjusted life year.

RESULTS

The cost-utility analysis illustrated that Home-WCD met the willingness-to-pay threshold with an incremental cost-effectiveness ratio of $20,103 per quality-adjusted life year and 4 mortalities prevented per 100 patients as compared with Home-No WCD. One-way sensitivity analyses demonstrated that Home-No WCD became the most cost-effective solution when the probability of SCA fell below 0.2% per week, the probability of SCA survival with a WCD fell below 9.8%, or the probability of SCA survival with Home-No WCD quadrupled from base-case assumptions.

CONCLUSION

Based on the existing literature probabilities of SCA in pediatric patients with DCM undergoing medical optimization before ICD implantation, sending a patient home with a WCD may be a cost-effective strategy.

Improved Left Ventricular Strain and Dyssynchrony After Pulmonary Artery Banding in an Infant with End-Stage Dilated Cardiomyopathy: Insights from Three-Dimensional Speckle Tracking

Pulmonary artery banding may benefit infants with dilated cardiomyopathy. We present the case of an infant with end-stage dilated cardiomyopathy and intractable heart failure who received pulmonary artery banding. Serial follow-up through two-dimensional and three-dimensional echocardiography revealed gradual improvement in the left ventricular ejection fraction and favorable remodeling. The result of three-dimensional speckle tracking suggested that this benefit is associated with improvements in global strain and intraventricular dyssynchrony.

Outcome for children following admission to hospital with a first episode of heart failure, due to heart muscle disease, in the ventricular assist device (VAD) era

AIMS

Most reports on the outcome of children who present with heart failure, due to heart muscle disease, are from an era when ventricular assist devices were not available. This study provides outcome data for the current era where prolonged circulatory support can be considered for most children.

METHODS & RESULTS

Data was retrieved on 100 consecutive children, who presented between 2010 - 2016, with a first diagnosis of unexplained heart failure. Hospital outcome was classified as either death, transplantation, recovery of function or persistent heart failure. Median age at presentation was 24 months and 58% were < 5 years old. Hospital mortality was 12% and 59% received a heart transplant. Most, 79%, of the transplants were carried out on patients with a device. Recovery of function was observed in 18% and 10% stabilised on oral therapy. Eighty-four percent of the deaths occurred in the <5 year old group. Shorter duration of support was associated with survival (34 days in survivors versus 106 in non-survivors, p = 0.01) and 72% were on an assist device at time of death.

CONCLUSION

Heart failure in children who require referral to a transplant unit is a serious illness with a high chance of either transplantation or death. Modifications in assist devices will be required to improve safety, especially for children < 5 years old where the donor wait may be prolonged. The identification of children who may recover function requires further study.

Left ventricular remodelling in long-term survivors after the arterial switch operation for transposition of the great arteries

Aims

The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO).

Methods and results

Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort.

Conclusion

Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.

Cardiomyopathy in Children: Classification and Diagnosis: A Scientific Statement From the American Heart Association

In this scientific statement from the American Heart Association, experts in the field of cardiomyopathy (heart muscle disease) in children address 2 issues: the most current understanding of the causes of cardiomyopathy in children and the optimal approaches to diagnosis cardiomyopathy in children. Cardiomyopathies result in some of the worst pediatric cardiology outcomes; nearly 40% of children who present with symptomatic cardiomyopathy undergo a heart transplantation or die within the first 2 years after diagnosis. The percentage of children with cardiomyopathy who underwent a heart transplantation has not declined over the past 10 years, and cardiomyopathy remains the leading cause of transplantation for children >1 year of age. Studies from the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry have shown that causes are established in very few children with cardiomyopathy, yet genetic causes are likely to be present in most. The incidence of pediatric cardiomyopathy is ≈1 per 100 000 children. This is comparable to the incidence of such childhood cancers as lymphoma, Wilms tumor, and neuroblastoma. However, the published research and scientific conferences focused on pediatric cardiomyopathy are sparcer than for those cancers. The aim of the statement is to focus on the diagnosis and classification of cardiomyopathy. We anticipate that this report will help shape the future research priorities in this set of diseases to achieve earlier diagnosis, improved clinical outcomes, and better quality of life for these children and their families.

Dilated cardiomyopathy in a pediatric population: etiology and outcome predictors - a single-center experience

AIM

The aim of the study was to assess predictors of outcome in patients hospitalized for dilated cardiomyopathy (DCM) and severe left ventricular dysfunction. Patients & methods: 83 pediatric patients hospitalized for heart failure due to DCM with coexistent left ventricular dysfunction were enrolled.

RESULTS

Overall, 5-year survival free from heart transplantation was 69.8%. Normalization of left ventricular function was achieved in 39.8% of patients during follow-up: younger age, less necessity of inotropic support and other than idiopathic DCM predicted left ventricular function, while familial history for cardiac disease or sudden death and inotropic support during hospitalization were associated with poorer outcome.

CONCLUSION

Almost 40% of patients with DCM experienced a complete normalization of cardiac function. Outcome was extremely variable according to the type of DCM.

Transcatheter left atrial decompression in patients with dilated cardiomyopathy: bridging to cardiac transplantation or recovery

BACKGROUND

Left atrial congestion results from backward failure in dilated cardiomyopathy. We aimed to evaluate feasibility and efficacy of percutaneous atrioseptostomy to create a restrictive atrial septum defect in management of dilated cardiomyopathy.Methods and resultsFrom June 2009 to December 2016, 27 interventions comprised left atria decompressions in 22 dilated cardiomyopathy patients; 9 females; age: 24 days to 36.9 years; weight: 3-50 kg; NYHA-/Ross class IV (n=16). Mean left ventricular ejection fraction was 21.5±9.7% and brain natriuretic peptide was 2291±1992 pg/ml. Dilated cardiomyopathy was classified as chronic (n=9); acute (n=1) myocarditis; idiopathic (n=5); left ventricular non-compaction (n=4); mitochondriopathy, pacemaker induced, and arrhythmogenic (n=3). Atrioseptostomy was concomitantly performed with myocardial biopsies 6.5 days (±11.7) after admission (n=11). Trans-septal puncture was used in 18 patients; foramen ovale dilatation was done in four patients. Mean balloon size was 11 mm (range 7-14 mm); total procedure time was 133±38 minutes. No procedural complications were observed. Mean left atrial pressure decreased from 15.8±6.8 to 12.2±4.8 mmHg (p=0.005), left/right atrial pressure gradient from 9.6±5.6 to 5±3.5 mmHg; brain natriuretic peptide (n=18) decreased from 1968±1606 to 830±1083 pg/ml (p=0.01). One patient unsuitable for heart transplantation died at home despite additionally performed pulmonary artery banding and three further left atrial decompressions; five patients were bridged to transplantation, two died afterwards. Functional recovery occurred in the remaining 14 patients and in six after additional pulmonary artery banding. No patient required assist device.

CONCLUSIONS

Percutaneous left atrial decompression is an age-independent, effective palliation treating patients with dilated cardiomyopathy.

From pediatrics to geriatrics: Mechanisms of heart failure across the life-course

Heart failure (HF) is a significant public health problem and a disease with high 5-year mortality. Although age is the primary risk factor for development of HF, it is a disease which impacts patients of all ages. Historically, HF has been studied as a one-size fits all strategy- with the majority of both clinical and basic science investigations employing adult male subjects or adult male pre-clinical animal models. We postulate that inclusion of biological variables in HF studies is necessary to improve our understanding of mechanisms of HF and improve outcomes. In this review, we will discuss age-specific differences in HF patients, particularly focusing on the pediatric and geriatric age groups. In addition, we will also discuss the biological variable of sex. Characterizing and understanding the mechanistic differences in these distinct HF populations can provide insights that will benefit and personalize therapeutic interventions. Further, we propose that future investigations into the cellular mechanisms involved in the developing and juvenile heart may provide valuable insights for targets that would be beneficial in aging patients.

Potential for and timing of recovery in children with dilated cardiomyopathy

OBJECTIVE

Understanding the clinical course and time-frame for recovery is helpful to guide management and counselling following a diagnosis of Dilated Cardiomyopathy (DCM). We aimed to document outcomes and time to recovery for a cohort of patients with a dilated cardiomyopathy phenotype.

METHODS

An observational cohort methodology was used to collect retrospective data from the departmental database for those identified with DCM. Data relating to mode of presentation, echocardiographic parameters, clinical management and outcome were collated and analysed. Predictors and time-scale for recovery were investigated and reported.

RESULTS

209 new referrals were included within the time frame. 82 children median age 1.0years (IQR 3.4) required intensive care (ICU) and their survival without death or transplant was 51% to one year and 45% to five years. 127 children presented to the pediatric heart failure clinic. Excluding 58 with neuromuscular disease, median age was 4.1years (IQR 11.3) & survival without death or transplant 85% to 1year and 50% to 5years. NT-proBNP normalized in survivors before echocardiographic parameters. Predictors of recovery included younger age, female sex and smaller left ventricular end diastolic Z score on echocardiogram at presentation.

CONCLUSION

Transplant-free survival to one year is significantly better for patients presenting to clinic, but longer-term survival is better amongst those presenting to ICU due to a late attrition in those with less severe heart failure at presentation. Falling NT-proBNP is the earliest marker of recovery. Recovery of cardiac function remains possible up to three years from presentation.

Bridge to recovery in children on ventricular assist devices-protocol, predictors of recovery, and long-term follow-up

BACKGROUND

The majority of children supported with ventricular assist devices (VADs) are bridged to heart transplantation. Although bridge to recovery has been reported, low recovery patient numbers has precluded systematic analysis. The aim of this study was to delineate recovery rates and predictors of recovery and to report on long-term follow-up after VAD explantation in children.

METHODS

Children bridged to recovery at our institution from January 1990 to May 2016 were compared with a non-recovery cohort. Clinical and echocardiographic data before and at pump stoppages and after VAD explantation were analyzed. Kaplan‒Meier estimates of event-free survival, defined as freedom from death or transplantation after VAD removal, were determined.

RESULTS

One hundred forty-nine children (median age 5.8 years) were identified. Of these, 65.2% had cardiomyopathy, 9.4% had myocarditis, and 24.8% had congenital heart disease. The overall recovery rate was 14.2%, and was 7.1% in patients with dilated cardiomyopathy. Predictors of recovery were age <2 years (recovery rate 27.8%, odds ratio [OR] 5.64, 95% confidence interval [CI] 2.0 to 16.6) and diagnosis of myocarditis (rate 57.1%; OR 17.56, 95% CI 4.6 to 67.4). After a median follow-up of 10.8 years, 15 patients (83.3%) were in Functional Class I and 3 (16.7%) in were in Class II. Mean left ventricular ejection fraction was 53% (range 28% to 64%). Ten- and 15-year event-free survival rates were both 84.1 ± 8.4%.

CONCLUSIONS

Children <2 years of age and those diagnosed with myocarditis have the highest probability of recovery. Long-term survival after weaning from the VAD was better than after heart transplantation, as demonstrated in the excellent long-term stability of ejection fraction and functional class.

Identifying Non-invasive Tools to Distinguish Acute Myocarditis from Dilated Cardiomyopathy in Children

There is often a diagnostic dilemma in pediatric patients presenting with depressed ventricular function, as myocarditis and dilated cardiomyopathy (DCM) of other etiologies can appear very similar. Accurate identification is critical to guide treatment and to provide families with the most accurate expectation of long-term outcomes. The objective of this study was to identify patterns of clinical presentation and to assess non-invasive measures to differentiate patients with acute myocarditis from other forms of DCM. We identified all children (< 18 years) from our institution with a diagnosis of idiopathic DCM or myocarditis based on endomyocardial biopsy or explant pathology (1996-2015). Characteristics at the time of presentation were compared between patients with a definite diagnosis of myocarditis and those with idiopathic DCM. Data collected included clinical and laboratory data, radiography, echocardiography, and cardiac catheterization data. A total of 58 patients were included in the study; 46 (79%) with idiopathic DCM and 12 (21%) with acute myocarditis. Findings favoring a diagnosis of myocarditis included a history of fever (58 vs. 15%, p = 0.002), arrhythmia (17 vs. 0%, p = 0.003), higher degree of cardiac enzyme elevation, absence of left ventricular dilation (42 vs. 7%, p = 0.002), segmental wall motion abnormalities (58 vs. 13%, p = 0.001), lower left ventricular dimension z-score (3.7 vs. 5.2, p = 0.031), and less severe depression of left ventricular systolic function. There are notable differences between patients with myocarditis and other forms of DCM that can be detected non-invasively at the time of presentation without the need for endomyocardial biopsy. These data suggest that it may be possible to develop a predictive model to differentiate myocarditis from other forms of DCM using non-invasive measures.

Cardiomyopathy in the pediatric patients

Pediatric cardiomyopathies are a group of myocardial diseases with complex taxonomies. Cardiomyopathy can occur in children at any age, and it is a common cause of heart failure and heart transplantation in children. The incidence of pediatric cardiomyopathy is increasing with time. They may be associated with variable comorbidities, which are most often arrhythmia, heart failure, and sudden death. Medical imaging technologies, including echocardiography, cardiac magnetic resonance, and nuclear cardiology, are helpful in reaching a diagnosis of cardiomyopathy. Nevertheless, endomyocardial biopsy is the final diagnostic method of diagnosis. Patients warrant surgical operations, such as palliative operations, bridging operations, ventricular septal maneuvers, and heart transplantation, if pharmaceutical therapies are ineffective. Individual therapeutic regimens due to pediatric characteristics, genetic factors, and pathogenesis may improve the effects of treatment and patients' survival.