Pediatric Cardiomyopathies

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.

ITPase deficiency causes a Martsolf-like syndrome with a lethal infantile dilated cardiomyopathy

Typical Martsolf syndrome is characterized by congenital cataracts, postnatal microcephaly, developmental delay, hypotonia, short stature and biallelic hypomorphic mutations in either RAB3GAP1 or RAB3GAP2. Genetic analysis of 85 unrelated "mutation negative" probands with Martsolf or Martsolf-like syndromes identified two individuals with different homozygous null mutations in ITPA, the gene encoding inosine triphosphate pyrophosphatase (ITPase). Both probands were from multiplex families with a consistent, lethal and highly distinctive disorder; a Martsolf-like syndrome with infantile-onset dilated cardiomyopathy. Severe ITPase-deficiency has been previously reported with infantile epileptic encephalopathy (MIM 616647). ITPase acts to prevent incorporation of inosine bases (rI/dI) into RNA and DNA. In Itpa-null cells dI was undetectable in genomic DNA. dI could be identified at a low level in mtDNA without detectable mitochondrial genome instability, mtDNA depletion or biochemical dysfunction of the mitochondria. rI accumulation was detectable in proband-derived lymphoblastoid RNA. In Itpa-null mouse embryos rI was detectable in the brain and kidney with the highest level seen in the embryonic heart (rI at 1 in 385 bases). Transcriptome and proteome analysis in mutant cells revealed no major differences with controls. The rate of transcription and the total amount of cellular RNA also appeared normal. rI accumulation in RNA-and by implication rI production-correlates with the severity of organ dysfunction in ITPase deficiency but the basis of the cellulopathy remains cryptic. While we cannot exclude cumulative minor effects, there are no major anomalies in the production, processing, stability and/or translation of mRNA.

Association of Soluble ST2 Serum Levels With Outcomes in Pediatric Dilated Cardiomyopathy

BACKGROUND

Prognosis in patients with pediatric dilated cardiomyopathy (PDCM) is urgently required to identify high-risk patients. Elevated soluble ST2 (sST2) is associated with prognosis in adult patients with heart failure. This study aimed to assess the prognostic value of sST2 in PDCM.

METHODS

Ninety-four patients with PDCM were enrolled after admission from 2 centres in China and followed up for adverse events (death, cardiac transplantation, and heart-failure-related rehospitalization). B-type natriuretic peptide (BNP) and sST2 levels were measured.

RESULTS

Over a median of 678 (interquartile range [IQR]: 533-785) days, 28 (29.8%) adverse events occurred. Patients in the highest tertile of sST2 levels had increased risk of short-term (< 6 months) (adjusted hazard ratio [HR]: 8.36, 95% confidence interval [CI], 1.02-73.52; P < 0.05) and long-term adverse events (2 years) (adjusted HR: 4.23; 95% CI, 1.32-13.60; P < 0.01) than those in lower tertiles. The C-statistic was increased with addition of sST2 to BNP from 0.697 (95% CI, 0.541-0.852) to 0.812 (95% CI, 0.697-0.939) for short-term and from 0.712 (95% CI, 0.604-0.819) to 0.798 (95% CI, 0.697-0.899) for prediction of long-term adverse events. An intermediate-risk subgroup was identified, and 24% had adverse events. When serial measurements were taken in a nested case-control subgroup, sST2 levels were constantly high in patients with late adverse events (> 6 months) but gradually decreased in nonadverse-event controls compared with 3-month and 6-month baseline levels.

CONCLUSIONS

In patients with PDCM, serum sST2 levels are associated with adverse events and have robust prognostic value. Serial measurements of sST2 could help in managing patients for monitoring outcomes of treatment.

Dilated cardiomyopathy with endocardial fibroelastosis in a juvenile Pallas cat

Dilated cardiomyopathy (DCM) is a myocardial disease characterized by ventricular chamber dilation associated with systolic myocardial dysfunction in the absence of other cardiac lesions. DCM occasionally develops in conjunction with proliferation of fibroelastic fibers in the endocardium, producing endocardial fibroelastosis (EFE). Although early reports describe EFE as a primary disease, evidence now suggests that EFE may develop as a response to myocardial dysfunction. Echocardiographic evaluation of a 4-wk-old Pallas cat ( Otocolobus manul) with respiratory distress revealed enlargement of both atria, enlarged end-systolic left ventricular dimension, and left ventricular dilation. DCM was diagnosed, and the cat was euthanized, given the poor prognosis. Postmortem examination revealed pericardial effusion and biventricular and biatrial enlargement. The interventricular septum and free walls of ventricles were thin. Histologically, the endocardium of the left and right ventricles was diffusely thickened; Verhoeff-Van Gieson staining of the left ventricular endocardium revealed a moderate amount of endocardial accumulation of elastin and collagen. These fibers were more prominent in papillary muscles and around coronary blood vessels. Based on these findings, we diagnosed DCM with EFE. Cardiac diseases are rarely diagnosed in wild felids.

Sudden Cardiac Arrest in a Young Population: Not So Unpredictable

See Article by Allan et al

A 14-year-old in heart failure with multiple cardiomyopathy variants illustrates a role for signal-to-noise analysis in gene test re-interpretation

Variants of unknown significance in cardiomyopathic disease should be analyzed systematically based on the prevalence of the variant in the population compared to prevalence of disease, evidence that other variants in the gene are pathologic, consistency of prediction software on pathogenicity, and the current clinical consensus.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

Complex roads from genotype to phenotype in dilated cardiomyopathy: scientific update from the Working Group of Myocardial Function of the European Society of Cardiology

Dilated cardiomyopathy (DCM) frequently affects relatively young, economically, and socially active adults, and is an important cause of heart failure and transplantation. DCM is a complex disease and its pathological architecture encounters many genetic determinants interacting with environmental factors. The old perspective that every pathogenic gene mutation would lead to a diseased heart, is now being replaced by the novel observation that the phenotype depends not only on the penetrance-malignancy of the mutated gene-but also on epigenetics, age, toxic factors, pregnancy, and a diversity of acquired diseases. This review discusses how gene mutations will result in mutation-specific molecular alterations in the heart including increased mitochondrial oxidation (sarcomeric gene e.g. TTN), decreased calcium sensitivity (sarcomeric genes), fibrosis (e.g. LMNA and TTN), or inflammation. Therefore, getting a complete picture of the DCM patient will include genomic data, molecular assessment by preference from cardiac samples, stratification according to co-morbidities, and phenotypic description. Those data will help to better guide the heart failure and anti-arrhythmic treatment, predict response to therapy, develop novel siRNA-based gene silencing for malignant gene mutations, or intervene with mutation-specific altered gene pathways in the heart.This article is part of the Mini Review Series from the Varenna 2017 meeting of the Working Group of Myocardial Function of the European Society of Cardiology.

Potential Common Pathogenic Pathways for the Left Ventricular Noncompaction Cardiomyopathy (LVNC)

Ventricular trabeculation and compaction are two essential morphogenetic events for generating a functionally competent ventricular wall. A significant reduction in trabeculation is usually associated with hypoplastic wall and ventricular compact zone deficiencies, which commonly leads to embryonic heart failure and early embryonic lethality. In contrast, the arrest of ventricular wall compaction (noncompaction) is believed to be causative to the left ventricular noncompaction (LVNC), a genetically heterogeneous disorder and the third most common cardiomyopathy among pediatric patients. After critically reviewing recent findings from genetically engineered mouse models, we suggest a model which proposes that defects in myofibrillogenesis and polarization in trabecular cardiomyocytes underly the common pathogenic mechanism for ventricular noncompaction.

Functional limitations and educational needs among children and adolescents with heart disease

OBJECTIVE

To examine how cognitive and motor limitations in children with heart disease are associated with education and participation in extracurricular activities.

DESIGN

Using 2009-2010 parent-reported data from the National Survey of Children with Special Health Care Needs (NS-CSHCN), we examined prevalence of five functional limitations (learning/concentration, communication, self-care, gross motor skills, and fine motor skills) by diagnosed heart disease status using chi-square tests and multivariable logistic regression. Among CSHCN with heart disease, we examined the associations between severity of each functional limitation and missing ≥11 days of school in the past year, receiving special education services, and interference with extracurricular activities.

RESULTS

CSHCN with heart disease (n = 1,416), compared to CSHCN without (n = 28,385), more commonly had "a lot" of difficulty in the five functional areas (P < .01; adjusted odds ratios: 1.8-3.3). Among CSHCN with heart disease, "a lot" of difficulty with learning/concentration was most common (35%), followed by communication (21%), self-care (14%), gross motor skills (12%), and fine motor skills (10%). Among CSHCN with heart disease, compared to those without, respectively, 27% and 15% missed ≥11 days of school, 45% and 29% received special education services, and 49% and 29% experienced interference with extracurricular activities (P < .01 for all). Level of difficulty with the five functional areas was associated with receipt of special education services and participation in extracurricular activities (P < .001).

CONCLUSION

These results support the American Heart Association recommendations to screen children with congenital heart disease for age-appropriate development and provide services when needed.

Initial presentation and management of pediatric heart failure

PURPOSE OF REVIEW

Heart failure is a rare but morbid diagnosis in the pediatric patient presenting to the emergency department (ED). Familiarity of the ED physician with the presentation, work-up, and management of pediatric heart failure is essential as accurate diagnosis is reliant on a high degree of suspicion.

RECENT FINDINGS

Studies evaluating pediatric heart failure are limited by its rarity and the heterogeneity of underlying conditions. However, recent reports have provided new data on the epidemiology, presentation, and outcomes of children with heart failure.

SUMMARY

The recent studies reviewed here highlight the significant diagnostic and management challenges that pediatric heart failure presents given the variety and lack of specificity of its presenting signs, symptoms, and diagnostic work-up. This review provides the ED physician with a framework for understanding of pediatric heart failure to allow for efficient diagnosis and management of these patients. The primary focus of this review is heart failure in structurally normal hearts.

Compound heterozygous loss-of-function mutations in KIF20A are associated with a novel lethal congenital cardiomyopathy in two siblings

Congenital or neonatal cardiomyopathies are commonly associated with a poor prognosis and have multiple etiologies. In two siblings, a male and female, we identified an undescribed type of lethal congenital restrictive cardiomyopathy affecting the right ventricle. We hypothesized a novel autosomal recessive condition. To identify the cause, we performed genetic, in vitro and in vivo studies. Genome-wide SNP typing and parametric linkage analysis was done in a recessive model to identify candidate regions. Exome sequencing analysis was done in unaffected and affected siblings. In the linkage regions, we selected candidate genes that harbor two rare variants with predicted functional effects in the patients and for which the unaffected sibling is either heterozygous or homozygous reference. We identified two compound heterozygous variants in KIF20A; a maternal missense variant (c.544C>T: p.R182W) and a paternal frameshift mutation (c.1905delT: p.S635Tfs*15). Functional studies confirmed that the R182W mutation creates an ATPase defective form of KIF20A which is not able to support efficient transport of Aurora B as part of the chromosomal passenger complex. Due to this, Aurora B remains trapped on chromatin in dividing cells and fails to translocate to the spindle midzone during cytokinesis. Translational blocking of KIF20A in a zebrafish model resulted in a cardiomyopathy phenotype. We identified a novel autosomal recessive congenital restrictive cardiomyopathy, caused by a near complete loss-of-function of KIF20A. This finding further illustrates the relationship of cytokinesis and congenital cardiomyopathy.

Cardiomyopathies: An Overview

The nonischemic cardiomyopathies are a diverse group of cardiac disorders that frequently cause heart failure and death and are now recognized with increasing frequency. There has been substantial progress in the clinical recognition and understanding of the natural history of these conditions. Well-established and new techniques of cardiac imaging are also helpful in this regard. Basic scientists are elucidating the pathogenesis and pathobiology of individual cardiomyopathies. In this compendium, some of the most important advances in this field are reviewed. Scientific opportunities to enhance further collaborative research to accelerate progress are identified.