Pediatric Cardiomyopathy Patients Research Articles

Intrinsic cardiomyopathy in pediatric Marfan syndrome: predictive factors and risk assessments.

Marfan syndrome (MFS) is associated with cardiovascular complications, particularly valvulopathies; however, its association with primary cardiomyopathy remains unclear. This retrospective cohort study examined the cardiomyopathy characteristics (CMCs) in pediatric patients with MFS. CMCs were defined as meeting at least one of the following echocardiography or clinical parameters: (1) cardiac index (CI) too low for patient's age, (2) ejection fraction (EF) <50%, and (3) diastolic dysfunction. The predictive factors for CMCs were determined using a multivariable logistic regression model. Among 83 patients with MFS (age, median [range], 12.5 [0.4-22.3] years), 39.8% exhibited CMCs. Only 4 patients (5%) showed heart failure symptoms (NYHA > 1). Independent predictors for CMCs included a systemic score of ≥7 (revised Ghent criteria) and likely pathogenic or pathogenic variants in FBN1, including variants that introduce a premature stop codon, splice site variants, and missense variants involving cysteine. A multivariable score was constructed with an AUC of 0.733. This study offers valuable insights into the prevalence and predictors of CMC in pediatric patients with MFS and presents potential strategies for risk assessment of cardiomyopathy. The objective of this study was to elucidate the contentious issue of intrinsic cardiomyopathy in Marfan syndrome and demonstrate its notable occurrence even in pediatric patients who do not exhibit heart failure symptoms or valvular complications. We highlighted the importance of specific FBN1 variants and higher systemic scores in identifying the potential for intrinsic cardiomyopathy in pediatric patients with Marfan syndrome.

(1330) - Practice Variation in Anticoagulation Management of Outpatient Pediatric Cardiomyopathy Patients: Survey of ACTION Providers

(1330) - Practice Variation in Anticoagulation Management of Outpatient Pediatric Cardiomyopathy Patients: Survey of ACTION Providers

Abstract 18860: Molecular Pathways Altered in Pediatric Dilated Cardiomyopathy Hearts Are Dependent on Disease Etiology

Introduction: Dilated cardiomyopathy presents a significant clinical burden in pediatric patients due to limited effective treatment options. This study hypothesizes molecular alterations in the heart of pediatric dilated cardiomyopathy (DCM) patients are dependent on specific etiologies. By understanding the molecular mechanisms underlying different etiologies, we aim to enhance diagnostics and guide future targeted therapies. An advanced understanding of the molecular mechanisms of DCM holds potential to transform pediatric cardiovascular care. Methods: RNA was extracted from the IRB approved University of Colorado's pediatric cardiac tissue bank. Samples included non-failing (NF), idiopathic dilated cardiomyopathy (IDCM), myocarditis, and left-ventricle non-compaction (LVNC) hearts. RNA-seq was performed using the Illumina HiSeq 4000 platform, and aligned using the TOPmed RNA-seq pipeline. Statistical analysis between NF and each etiology was performed to identify fold changes and q-values. Gene expression analysis was further examined using Ingenuity Pathway Analysis (Qiagen). Results: Demographics of patient samples were as follows: NF (N=23, % male=61%, Median age=13.65 years, Interquartile range (IQR)=8.6), IDCM (N=20, % male=55%, Median age=9.83 years, IQR=8.98), myocarditis (N=4, % male=75%, Median age=0.35 years, IQR=0.1), LVNC (N=3, % male=33.3%, Median age=0.27 years, IQR= Undetermined). Comparisons between NF versus IDCM, NF versus myocarditis, and NF versus LVNC hearts revealed noteworthy differences in gene expression patterns. Pathways associated with IDCM related to inflammation and immune response trends, whereas DNA repair and cellular damage were strongly associated with myocarditis. Lastly, analysis of LVNC hearts suggest pathways associated with ischemic remodeling. Conclusions: In conclusion, our study provides insights into gene expression patterns associated with different etiologies of DCM in pediatric patients. Distinct patterns were observed between non-failing and IDCM, myocarditis, or LVNC hearts. These findings have implications for improving diagnostics and guiding targeted therapies in pediatric DCM management.

Diagnostic Yield of Exome Sequencing in Pediatric Cardiomyopathy

To assess the diagnostic yield of exome sequencing (ES) in pediatric cardiomyopathy. A single-institution, retrospective chart review of 91 patients with pediatric cardiomyopathy was performed. While pediatric cardiomyopathy is often genetic in nature, no genetic test is recommended as standard of care. All our patients were diagnosed with cardiomyopathy and evaluated by a medical geneticist between January 2010 through September 2022. Demographic information and clinical data were abstracted. Of 91 patients with pediatric cardiomyopathy, 36 (39.6%) received a diagnosis by ES. Twenty-two (61.1%) of these diagnoses would have been missed on cardiac multigene panel testing. The diagnostic yield for cardiomyopathy presenting under 1year of age was 38.3%, while the yield for patients over 1year of age was 41.9%. ES has a high diagnostic yield in pediatric cardiomyopathy compared with a gene panel. Over 60% of patients with diagnosis by ES would not have received their molecular genetic diagnosis if only multigene panel testing was sent. Diagnostic yield did not vary significantly between the subtypes of cardiomyopathy and patient age groups, highlighting the likely clinical utility of ES for all pediatric cardiomyopathy patients.

Evaluating the Utility of a New Pathogenicity Predictor for Pediatric Cardiomyopathy

Pediatric cardiomyopathy (CM) has significant childhood morbidity and mortality which is caused by both genetic and environmental factors. Previous research has focused on identifying genetic variants in pediatric CM for diagnostic purposes, but not for risk stratification. The current study was modeled after previous work which showed an association between CardioBoost-classified disease-causing variants and an increased risk for severe clinical outcomes in adults with CM to assess if the same association is true in pediatric CM. This was a retrospective, single-center cohort study that evaluated outcomes in pediatric CM patients who were evaluated by the Children’s Hospital of Philadelphia (CHOP). CardioBoost (CB) scores were generated for these patients, and scores were categorized as ≤0.1, 0.1-0.9, and ≥0.9. Composite endpoint was freedom from a major adverse cardiac event (MACE). 104 patients were included in the final analysis. 32 (31%) had DCM, 45 (43%) had HCM, and 27 (26%) had other CM. There was no significant association between CB score and clinical outcome in pediatric CM patients. Overall, this study highlights the continued deficits in variant interpretation for pediatric CM. We recommend using caution when applying this tool to stratify clinical outcomes in the pediatric population.

Age and Sex Differences in the Genetics of Cardiomyopathy

Cardiomyopathy has variable penetrance. We analyzed age and sex-related genetic differences in 1,397 cardiomyopathy patients (Ontario, UK) with whole genome sequencing. Pediatric cases (n = 471) harbored more deleterious protein-coding variants in Tier 1 cardiomyopathy genes compared to adults (n = 926) (34.6% vs 25.9% respectively, p = 0.0015), with variant enrichment in constrained coding regions. Pediatric patients had a higher burden of sarcomere and lower burden of channelopathy gene variants compared to adults. Specifically, pediatric patients had more MYH7 and MYL3 variants in hypertrophic cardiomyopathy, and fewer TTN truncating variants in dilated cardiomyopathy. MYH7 variants clustered in the myosin head and neck domains in children. OBSCN was a top mutated gene in adults, enriched for protein-truncating variants. In dilated cardiomyopathy, female patients had a higher burden of z-disc gene variants compared to males. Genetic differences may explain age and sex-related variability in cardiomyopathy penetrance. Genotype-guided predictions of age of onset can inform pre-test genetic counseling.Graphical Pediatric cardiomyopathy patients were more likely to be genotype-positive than adults with a higher burden of variants in MYH7, MYL3, TNNT2, VCL. Adults had a higher burden of OBSCN and TTN variants. Females with dilated cardiomyopathy (DCM) had a higher burden of z-disc gene variants compared to males.

Clinical Outcomes and Genetic Analyses of Restrictive Cardiomyopathy in Children.

Restrictive cardiomyopathy in children is rare and outcomes are very poor. However, little information is available concerning genotype-outcome correlations. We analyzed the clinical characteristics and genetic testing, including whole exome sequencing, of 28 pediatric restrictive cardiomyopathy patients who were diagnosed from 1998 to 2021 at Osaka University Hospital in Japan. The median age at diagnosis (interquartile range) was 6 (2.25-8.5) years. Eighteen patients received heart transplantations and 5 patients were on the waiting list. One patient died while waiting for transplantation. Pathologic or likely-pathogenic variants were identified in 14 of the 28 (50%) patients, including heterozygous TNNI3 missense variants in 8 patients. TNNT2, MYL2, and FLNC missense variants were also identified. No significant differences in clinical manifestations and hemodynamic parameters between positive and negative pathogenic variants were detected. However, 2- and 5-year survival rates were significantly lower in patients with pathogenic variants (50% and 22%) compared with survival in patients without pathogenic variants (62% and 54%; P=0.0496, log-rank test). No significant differences were detected in the ratio of patients diagnosed at nationwide school heart disease screening program between positive and negative pathogenic variants. Patients diagnosed by school screening showed better transplant-free survival compared with patients diagnosed by heart failure symptoms (P=0.0027 in log-rank test). In this study, 50% of pediatric restrictive cardiomyopathy patients had pathogenic or likely-pathogenic gene variants, and TNNI3 missense variants were the most frequent. Patients with pathogenic variants showed significantly lower transplant-free survival compared with patients without pathogenic variants.

Serum from pediatric dilated cardiomyopathy patients promotes dysregulation of cardiolipin biosynthesis and mitochondrial dysfunction in primary cardiomyocytes

Pediatric dilated cardiomyopathy (DCM) is a devastating and poorly understood disease with most clinical treatment paradigms extrapolated from the adult population. Our studies showed that aspects of metabolism and mitochondrial function are dysregulated in pediatric hearts. Cardiolipin (CL), a unique phospholipid in the inner mitochondrial membrane, is essential for optimal mitochondrial function and was shown to be dysregulated in failing adult and pediatric human heart.

Human versus machine: does artificial intelligence add value to identification of hypertrophic cardiomyopathy in pediatric patients?

Abstract Introduction An abnormal increase in left ventricular thickness is a hallmark of hypertrophic cardiomyopathy (HCM). Although standard measures of left ventricular voltage abnormalities on electrocardiograms (ECGs) have high false positive rates and poor correlation to left ventricular thickness, ECGs continue to be part of most screening programs. We developed a machine learning model for HCM classification from ECG in a pediatric cohort and compared its efficacy to that of clinician specialists. Purpose To compare clinician-based predictions of HCM to a machine learning model trained to classify pediatric patients with HCM utilizing 12-lead ECG. Methods ECGs from patients &amp;lt;19 years with HCM, including those with HCM gene mutations, were compared to those from age- and sex-matched controls with normal heart structure and function on echocardiogram. Patients with a known history of primary causes of left ventricular hypertrophy such as aortic stenosis or glycogen storage disease were excluded. A cascaded convolutional neural network was developed combining a residual neural network with a 2-layer dense neural network with 10-fold cross validation. The performance of the machine learning based HCM classification was compared to that of two independent clinicians. Results Analytic sample included data from 82 patients with clinical HCM compared to 91 healthy control subjects. The machine model AUC was 0.89 (0.84–0.94). Clinician inter-rater reliability was 0.8. The clinicians had a higher specificity (97% vs 82%) but lower sensitivity (50% vs 78%) than the machine learning model. Compared to clinician-classification, the positive predictive value was lower in the machine model (82% vs 93%). Conclusion In this preliminary study, machine learning classification of HCM utilizing 12-lead ECG had greater sensitivity than that of clinician interpretation. Machine learning may play a role in screening and diagnosis, including in subjects with normal-appearing ECG. Evaluation of its utility in a larger cohort is needed. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Le Bonheur Children's Hospital

Serum from pediatric dilated cardiomyopathy patients promotes dysregulation of cardiolipin biosynthesis and mitochondrial dysfunction in primary cardiomyocytes

Pediatric dilated cardiomyopathy (DCM) is a devastating and poorly understood disease with most clinical treatment paradigms extrapolated from the adult population. Our studies showed that aspects of metabolism and mitochondrial function are dysregulated in pediatric hearts. Cardiolipin (CL), a unique phospholipid in the inner mitochondrial membrane, is essential for optimal mitochondrial function and was shown to be dysregulated in failing adult and pediatric human heart. Our objective is to investigate if serum circulating factors from pediatric DCM patients can remodel CL resulting in mitochondrial dysfunction in vitro, similar to what is observed in the failing pediatric heart. Using a novel in vitro model that consists of treating neonatal rat ventricular myocytes (NRVMs) with serum from pediatric DCM patients or from non-failing (NF) healthy controls, mitochondrial respiration was assessed using the Agilent Seahorse, and reactive oxygen species (ROS) was assessed using Electron Paramagnetic Resonance Spectroscopy. Relative mtDNA copy number was determined by qPCR and expression of enzymes involved in CL biosynthesis were analyzed using RT-qPCR. Mass-spectrometry was used to quantitate total and specific CL species and to investigate the metabolite composition of NRVMs treated with NF or DCM serum. While mitochondrial ROS and mtDNA copy number were not significantly altered, we show that DCM serum decreases mitochondrial function, which is associated with alterations in CL content and composition and the downregulation of enzymes implicated in CL biosynthesis. Analysis of metabolite content showed an alteration of pathways involved in fatty acid metabolism, mitochondrial biogenesis and regulation of β-oxidation by PPARα. In conclusion, pediatric DCM serum circulating factors can promote CL remodeling resulting in mitochondrial dysfunction in primary cardiomyocytes. These findings suggest that CL could be a novel therapeutic target for this particular population.

Machine learning can identify hypertrophic cardiomyopathy in pediatric patients using electrocardiogram

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Le Bonheur Children’s Hospital Background Hypertrophic cardiomyopathy (HCM) is the most common genetic based heart disease and is associated with sudden cardiac death, particularly in young athletes. Standard measures of voltage abnormalities on electrocardiograms (ECGs) have demonstrated high false positive rates and poor correlation of LV thickness. Despite poor testing characteristics, ECGs continue to be part of most adolescent and family screening programs. While recent studies suggest that machine learning based analysis of ECGs may have utility in the identification of HCM in adult patients, there are limited data regarding its effectiveness in the pediatric population. Purpose The purpose of this study was to develop a deep learning model utilizing raw digital ECG data to accurately distinguish healthy pediatric patients from those with HCM. Methods ECGs from patients &amp;lt; 19 years with HCM were compared to ECGs from age- and sex-matched patients that underwent evaluation with ECG and echocardiogram for chest pain, sports clearance, syncope, or abnormal ECG between January 2011 and March 2021. Patients with a known clinical history of primary causes of left ventricular hypertrophy such as aortic stenosis, systemic hypertension, and glycogen storage disease were excluded from the study. Unsupervised signal processing tools including descriptive statistics and wavelet transformation were used to extract features from 12-lead ECG signals. A cascaded convolutional neural network was developed combining a residual neural network to extract features from waveform 12-lead ECG signals with a 2-layer dense neural network to embed features from signal processing tools. Model performance was evaluated by 10-fold stratified cross validation. Results The analytic sample included 181 patients (72% male; 63% Caucasian). Mean age was 12.3 ± 5.8 years. A cascaded deep learning model classified patients into healthy or HCM categories with a cross validation sensitivity of 77.7% and specificity of 81.6%. The positive predictive value was 82% and AUC of 0.89 (0.84-0.94). Conclusion This CNN trained with a relatively small number of images was able to accurately identify HCM in pediatric patients from standard 12-lead ECG. Evaluation of its potential utility in larger populations is needed.

Whole genome sequencing delineates regulatory, copy number, and cryptic splice variants in early onset cardiomyopathy

Cardiomyopathy (CMP) is a heritable disorder. Over 50% of cases are gene-elusive on clinical gene panel testing. The contribution of variants in non-coding DNA elements that result in cryptic splicing and regulate gene expression has not been explored. We analyzed whole-genome sequencing (WGS) data in a discovery cohort of 209 pediatric CMP patients and 1953 independent replication genomes and exomes. We searched for protein-coding variants, and non-coding variants predicted to affect the function or expression of genes. Thirty-nine percent of cases harbored pathogenic coding variants in known CMP genes, and 5% harbored high-risk loss-of-function (LoF) variants in additional candidate CMP genes. Fifteen percent harbored high-risk regulatory variants in promoters and enhancers of CMP genes (odds ratio 2.25, p = 6.70 × 10−7 versus controls). Genes involved in α-dystroglycan glycosylation (FKTN, DTNA) and desmosomal signaling (DSC2, DSG2) were most highly enriched for regulatory variants (odds ratio 6.7–58.1). Functional effects were confirmed in patient myocardium and reporter assays in human cardiomyocytes, and in zebrafish CRISPR knockouts. We provide strong evidence for the genomic contribution of functionally active variants in new genes and in regulatory elements of known CMP genes to early onset CMP.

Serum from pediatric dilated cardiomyopathy patients promotes dysregulation of cardiolipin biosynthesis and mitochondrial dysfunction

Pediatric dilated cardiomyopathy (DCM) is a devastating and poorly understood disease with most clinical treatment paradigms extrapolated from the adult population. Our studies showed that aspects of metabolism and mitochondria function are dysregulated in pediatric hearts. Cardiolipin (CL), a unique phospholipid in the inner mitochondrial membrane, is essential for optimal mitochondrial function and was shown to be dysregulated in failing adult hearts. We investigate if serum circulating factors from pediatric DCM patients can remodel CL resulting in mitochondrial dysfunction similar to what is observed in the failing pediatric heart. Using a novel in vitro model that consists of treating neonatal rat ventricular myocytes (NRVMs) with serum from pediatric DCM patients or from non-failing (NF) healthy controls, mitochondrial respiration was assessed using Seahorse assay, and reactive oxygen species (ROS) was assessed using Electron Paramagnetic Resonance Spectroscopy. Expression of enzymes involved in CL biosynthesis and remodeling were analyzed using RT-qPCR and relative mtDNA copy number determined by qPCR. Mass spectroscopy was used to quantitate total and specific CL species and to investigate the metabolite composition of NRVMs treated with NF or DCM serum. While mitochondrial ROS and copy number were not significantly altered, we showed that DCM serum decreases mitochondrial function, which is associated with alterations in CL content and composition and gene expression of enzymes implicated in CL biosynthesis and remodeling. Analysis of metabolite content showed an alteration of pathways involved in fatty acid metabolism, mitochondrial biogenesis and regulation of β-oxidation by PPARα. Pediatric DCM serum circulating factors can promote CL remodeling resulting in mitochondrial dysfunction in cardiomyocytes. These findings suggest that CL could be a therapeutic target for this particular population.

Racial Disparities in Hospital Mortality Among Pediatric Cardiomyopathy and Myocarditis Patients.

Racially disparate health outcomes exist for a multitude of populations and illnesses. It is unknown how race and ethnicity impact mortality for children with cardiomyopathy or myocarditis. This retrospective cross-sectional study employed the Kids' Inpatient Database to analyze 34,617 hospital admissions for patients ≤ 18years old with cardiomyopathy, myocarditis, or both, without concomitant congenital heart disease. Multivariate logistic regression models investigated the impact of race/ethnicity on in-hospital mortality adjusting for age, calendar year, sex, insurance type, diagnostic category, treatment at a pediatric hospital, and non-cardiac organ dysfunction. African American race and Hispanic ethnicity were independent risk factors for mortality (African American: odds ratio (OR) 1.25, 95% confidence interval (CI) 1.01-1.53 and Hispanic: OR 1.29, 95% CI 1.03-1.60). African American race was also found to be significantly associated with the use of extracorporeal membrane oxygenation (ECMO), mortality while on ECMO, and cardiac arrest. Adjusting the regression model for ECMO and arrest attenuated the impact of African American race on mortality, suggesting that these variables may indeed play a role in explaining the impact of race on mortality for African American patients with myocardial disease. Hispanic ethnicity remained associated with higher risk of mortality despite controlling for all mechanical circulatory support and transplant (OR 1.30, 95% CI 1.04-1.63). Children of racial and ethnic minorities hospitalized with cardiomyopathy or myocarditis are more likely to die than their white counterparts, a trend that may be due at least in part to in-hospital differences in care or response to therapy.

Waitlist and Post–Heart Transplant Outcomes for Children With Nondilated Cardiomyopathy

Although outcomes for pediatric cardiomyopathy (CMP) patients have improved, an understanding of outcomes by CMP phenotype is essential. This study assessed changes in waitlist and post-transplant survival in nondilated cardiomyopathy (DCM) patients over 2 decades, explored ventricular assist device (VAD) utilization in this cohort, and identified risk factors for waitlist and posttransplant mortality in the current era. Pediatric patients with a diagnosis of CMP listed for heart transplantation during three eras: Era 1: March 5, 1999 to December 31, 2004; Era 2: January 1, 2005 to December 15, 2011; and Era 3 (current era): December 16, 2011 to February 28, 2018 were included. Multivariable Cox proportional hazards regression was performed to assess waitlist and posttransplant survival. Compared with patients with DCM, those with hypertrophic and restrictive cardiomyopathy in the current era are less likely to be on VAD (23.4% vs 2.7% vs 4.5%); listed United Network for Organ Sharing Status 1A (75.6% vs 39.8% vs 34.8%), and more likely to have longer waitlist times (P < .01 for all). Only 3.3% hypertrophic and 2.4% restrictive cardiomyopathy patients had VAD implantation, although VAD use did not adversely impact waitlist survival in weighted non-DCM patients. Significant improvements have occurred in waitlist survival of hypertrophic and posttransplant survival of both types of non-DCM patients. Currently, waitlist and posttransplant survival is similar for all CMP phenotypes. VAD use is low in patients with non-DCM, although this did not increase waitlist mortality in adjusted analysis. Further studies in patients with non-DCM are needed to determine optimal timing and anatomic characteristics most likely to benefit from VAD implantation during the waitlist period.

Retrospective Analysis of Clinical Genetic Testing in Pediatric Primary Dilated Cardiomyopathy: Testing Outcomes and the Effects of Variant Reclassification.

BackgroundGenetic testing in pediatric primary dilated cardiomyopathy (DCM) patients has identified numerous disease‐causing variants, but few studies have evaluated genetic testing outcomes in this population in the context of patient and familial clinical data or assessed the clinical implications of temporal changes in genetic testing results.Methods and ResultsWe performed a retrospective analysis of all patients with primary DCM who presented to our institution between 2008 and 2018. Variants identified by genetic testing were reevaluated for pathogenicity on the basis of current guidelines for variant classification. A total of 73 patients with primary DCM presented to our institution and 63 (86%) were probands that underwent cardiomyopathy‐specific gene testing. A disease‐causing variant was identified in 19 of 63 (30%) of cases, with at least 9/19 (47%) variants occurring de novo. Positive family history was not associated with identification of a causal variant. Reclassification of variants resulted in the downgrading of a large proportion of variants of uncertain significance and did not identify any new disease‐causing variants.ConclusionsClinical genetic testing identifies a causal variant in one third of pediatric patients with primary DCM. Variant reevaluation significantly decreased the number of variants of uncertain significance, but a large burden of variants of uncertain significance remain. These results highlight the need for periodic reanalysis of genetic testing results, additional investigation of genotype‐phenotype correlations in DCM through large, multicenter genetic studies, and development of improved tools for functional characterization of variants of uncertain significance.

Expanding the clinical and genetic spectrum of ALPK3 variants: Phenotypes identified in pediatric cardiomyopathy patients and adults with heterozygous variants

Biallelic damaging variants in ALPK3, encoding alpha-protein kinase 3, cause pediatric-onset cardiomyopathy with manifestations that are incompletely defined. We analyzed clinical manifestations of damaging biallelic ALPK3 variants in 19 pediatric patients, including nine previously published cases. Among these, 11 loss-of-function (LoF) variants, seven compound LoF and deleterious missense variants, and one homozygous deleterious missense variant were identified. Among 18 live-born patients, 8 exhibited neonatal dilated cardiomyopathy (44.4%; 95% CI: 21.5%-69.2%) that subsequently transitioned into ventricular hypertrophy. The majority of patients had extracardiac phenotypes, including contractures, scoliosis, cleft palate, and facial dysmorphisms. We observed no association between variant type or location, disease severity, and/or extracardiac manifestations. Myocardial histopathology showed focal cardiomyocyte hypertrophy, subendocardial fibroelastosis in patients under 4 years of age, and myofibrillar disarray in adults. Rare heterozygous ALPK3 variants were also assessed in adult-onset cardiomyopathy patients. Among 1548 Dutch patients referred for initial genetic analyses, we identified 39 individuals with rare heterozygous ALPK3 variants (2.5%; 95% CI: 1.8%-3.4%), including 26 missense and 10 LoF variants. Among 149 U.S. patients without pathogenic variants in 83 cardiomyopathy-related genes, we identified six missense and nine LoF ALPK3 variants (10.1%; 95% CI: 5.7%-16.1%). LoF ALPK3 variants were increased in comparison to matched controls (Dutch cohort, P = 1.6×10-5; U.S. cohort, P = 2.2×10-13). Biallelic damaging ALPK3 variants cause pediatric cardiomyopathy manifested by DCM transitioning to hypertrophy, often with poor contractile function. Additional extracardiac features occur in most patients, including musculoskeletal abnormalities and cleft palate. Heterozygous LoF ALPK3 variants are enriched in adults with cardiomyopathy and may contribute to their cardiomyopathy. Adults with ALPK3 LoF variants therefore warrant evaluations for cardiomyopathy.

P4654Clinical and electrocardiographic features of restrictive cardiomyopathy in children

Abstract Introduction Restrictive cardiomyopathy (RCM) is a rare myocardial disease with an impaired diastolic function and poor prognosis. The mean survival duration after a diagnosis of RCM is reported to be around 2 years in children and most need heart transplantations. Purpose This study aimed to determine the 12-lead electrocardiogram (ECG) diagnostic criteria of RCM based on the initial diagnostic electrocardiogram. Methods ECGs in pediatric cardiomyopathy patients were collected from 15 institutes in Japan between 1979 and 2013. We compared the ECG findings, especially of the P wave, in RCM patients between the cardiomyopathy group and healthy children group separately for each gender and the age. The ECGs in the healthy group were obtained from school heart screening in Japan of first-graders, and seventh-graders. Statistical significance was determined as p&lt;0.001. Results Among 376 registered cardiomyopathy patients, 63 had hypertrophic cardiomyopathy (HCM) (36%), 91 (24%) dilated cardiomyopathy (DCM), 106 (28%) a left ventricular myocardial noncompaction (LVNCs), 25 (7%) restrictive cardiomyopathy (RCM), 14 (4%) arrhythmogenic right ventricular cardiomyopathy (ARVC), and 5 (1%) other cardiomyopathies. Of the 25 RCM patients (9.9±3.4 years old, F:M=11:14), 36% were discovered during school heart screening. The first onset was an abnormal ECG in 9, symptoms of heart failure in 6, respiratory tract infections in 3, syncope in 1, and 6 with other. Of those patients, 2 (8%) had a family history of RCM, 24 (92%) no family history. A genetic diagnosis was performed in 5 of the 25 cases, and 3 had genetic abnormalities related to RCM. The mean follow-up period was 65±95 months (mean±standard deviation). During follow up, 19 patients (76%) survived, 6 (24%) died, 7 (28%) had heart transplantations, and 3 (12%) were waiting for heart transplantations with a left ventricular assist device. The P wave was bimodal in lead I or biphasic in lead V1 in 15 patients (93%), and 13 (81%) patients had both variations. We evaluated the duration and amplitude of the first and second component of the P wave as P1 and P2. The number of control and RCM patients (control/RCM), duration of P1+P2, and sum total absolute value of the amplitude of P1+P2 in lead V1 were 8350/5, 90±9/116±10ms, and 72±28/528±278μV in first grade boys, 8423/3, 91±10/120±22ms, and 66±28/326±229μV in first grade girls, 8943/1, 97±1/100ms, and 71±31/328μV in seventh grade boys, and 9183/5, 98±11/112±10ms, and 55±27/315±56μV in seventh grade girls. Although the number of patients in the RCM group was small, sum total absolute value of the amplitude of P1+P2 in lead V1 showed a significant difference in any group. Conclusion The ECG in children with RCM exhibits P wave abnormalities in almost all patients. In particular, not the P wave interval but P wave shape in I and V1 and the sum total absolute value of the amplitude of P1+P2 in lead V1 were observed differences.

Green tea extract catechin improves cardiac function in pediatric cardiomyopathy patients with diastolic dysfunction

BackgroundOur previous studies have demonstrated that Ca2+ desensitizing catechin could correct diastolic dysfunction in experimental animals with restrictive cardiomyopathy. In this study, it is aimed to assess the effects of green tea extract catechin on cardiac function and other clinical features in pediatric patients with cardiomyopathies.MethodsTwelve pediatric cardiomyopathy patients with diastolic dysfunction were enrolled for the study. Echocardiography, ECG, and laboratory tests were performed before and after the catechin administration for 12 months. Comparison has been made in these patients before and after the treatment with catechin. Next Generation Sequencing was conducted to find out the potential causative gene variants in all patients.ResultsA significant decrease of isovolumetric relaxation time (115 ± 46 vs 100 ± 42 ms, P = 0.047 at 6 months; 115 ± 46 vs 94 ± 30 ms, P = 0.033 at 12 months), an increase of left ventricle end diastolic volume (40 ± 28 vs 53 ± 28 ml, P = 0.028 at 6 months; 40 ± 28 vs 48 ± 33 ml, P = 0.011 at 12 months) and stroke volume (25 ± 16 vs 32 ± 17 ml, P = 0.022 at 6 months; 25 ± 16 vs 30 ± 17 ml, P = 0.021 at 12 months) were observed with echocardiography in these patients 6-month after the treatment with catechin. Ejection fraction, left ventricular wall thickness, biatrial dimension remained unchanged. No significant side effects were observed in the patients tested.ConclusionsThis study indicates that Ca2+ desensitizing green tea extract catechin, is helpful in correcting the impaired relaxation in pediatric cardiomyopathy patients with diastolic dysfunction.

CHARACTERISTICS AND LONGER-TERM OUTCOMES OF PEDIATRIC PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY: A TERTIARY CARE CENTER EXPERIENCE

We sought to describe outcomes of pediatric hypertrophic cardiomyopathy (PHCM) patients. We studied 398 consecutive PHCM patients (<18 years, 12±5 years, 65% males) seen at our center between 2002-2018. Baseline clinical & echo data was collected. Z-score for left ventricular (LV) wall thickness