The impact of damaging epilepsy and cardiac genetic variant burden in sudden death in the young

BACKGROUND

Sudden unexpected death in children is a tragic event. Understanding the genetics of sudden death in the young (SDY) enables family counseling and cascade screening. The objective of this study was to characterize genetic variation in an SDY cohort using whole genome sequencing.

METHODS

The SDY Case Registry is a National Institutes of Health/Centers for Disease Control and Prevention surveillance effort to discern the prevalence, causes, and risk factors for SDY. The SDY Case Registry prospectively collected clinical data and DNA biospecimens from SDY cases < 20 years of age. SDY cases were collected from medical examiner and coroner offices spanning 13 US jurisdictions from 2015 to 2019. The cohort included 211 children (median age 0.33 year; range 0-20 years), determined to have died suddenly and unexpectedly and from whom DNA biospecimens for DNA extractions and next-of-kin consent were ascertained. A control cohort consisted of 211 randomly sampled, sex- and ancestry-matched individuals from the 1000 Genomes Project. Genetic variation was evaluated in epilepsy, cardiomyopathy, and arrhythmia genes in the SDY and control cohorts. American College of Medical Genetics/Genomics guidelines were used to classify variants as pathogenic or likely pathogenic. Additionally, pathogenic and likely pathogenic genetic variation was identified using a Bayesian-based artificial intelligence (AI) tool.

RESULTS

The SDY cohort was 43% European, 29% African, 3% Asian, 16% Hispanic, and 9% with mixed ancestries and 39% female. Six percent of the cohort was found to harbor a pathogenic or likely pathogenic genetic variant in an epilepsy, cardiomyopathy, or arrhythmia gene. The genomes of SDY cases, but not controls, were enriched for rare, potentially damaging variants in epilepsy, cardiomyopathy, and arrhythmia-related genes. A greater number of rare epilepsy genetic variants correlated with younger age at death.

CONCLUSIONS

While damaging cardiomyopathy and arrhythmia genes are recognized contributors to SDY, we also observed an enrichment in epilepsy-related genes in the SDY cohort and a correlation between rare epilepsy variation and younger age at death. These findings emphasize the importance of considering epilepsy genes when evaluating SDY.

SCMR expert consensus statement for cardiovascular magnetic resonance of patients with a cardiac implantable electronic device

Cardiovascular magnetic resonance (CMR) is a proven imaging modality for informing diagnosis and prognosis, guiding therapeutic decisions, and risk stratifying surgical intervention. Patients with a cardiac implantable electronic device (CIED) would be expected to derive particular benefit from CMR given high prevalence of cardiomyopathy and arrhythmia. While several guidelines have been published over the last 16 years, it is important to recognize that both the CIED and CMR technologies, as well as our knowledge in MR safety, have evolved rapidly during that period. Given increasing utilization of CIED over the past decades, there is an unmet need to establish a consensus statement that integrates latest evidence concerning MR safety and CIED and CMR technologies. While experienced centers currently perform CMR in CIED patients, broad availability of CMR in this population is lacking, partially due to limited availability of resources for programming devices and appropriate monitoring, but also related to knowledge gaps regarding the risk-benefit ratio of CMR in this growing population. To address the knowledge gaps, this SCMR Expert Consensus Statement integrates consensus guidelines, primary data, and opinions from experts across disparate fields towards the shared goal of informing evidenced-based decision-making regarding the risk-benefit ratio of CMR for patients with CIEDs.

Similar success rate in proximal and distal colonic stent placement: a retrospective multi-center study

OBJECTIVES

Stenting of malignant colon obstruction is used as a bridge to surgery or as an alternative to surgical colostomy in a palliative setting. Current guidelines recommend stent placement as the first line of treatment in colonic obstruction in both curative and palliative settings. However, it is unclear whether the location of the malignant obstruction influences the outcome of the stenting procedure. The goal of this study was to compare the outcomes of colonic stents between proximal and distal colonic strictures with regard to technical and clinical success and the risk of adverse events.

METHODS

A multi-center retrospective cohort was composed of patients who underwent a colonic stent placement at two tertiary hospitals between 2013 and 2021. The technical and clinical outcome, stent type used, duration of post-procedural hospital stay and complications were noted.

RESULTS

A total of 148 patients who underwent colonic stenting were identified. 41 patients underwent stent placement in the proximal colon and 107 patients underwent a distal stent placement. There was no difference in technical success (100% vs 96.3%, p = 0.209), clinical success (97.0% vs 89.6%, p = 0.199) or complications (24.4% vs 37.4%, p = 0,135).

CONCLUSION

Technical success and clinical success rates are high and do not differ between stent locations. There is no significant difference in complication rates between proximal and distal colonic stents.

Multicenter retrospective evaluation of magnetic resonance imaging in pediatric and congenital heart disease patients with cardiac implantable electronic devices

BACKGROUND

Guidelines addressing magnetic resonance imaging (MRI) in patients with cardiac implantable electronic devices (CIEDs) provide algorithms for imaging pediatric and congenital heart disease (CHD) patients. Guideline acceptance varies by institution. Guidelines also do not support routine MRI scans in patients with epicardial or abandoned leads, common in pediatric and CHD patients.

OBJECTIVE

The purpose of this study was to determine the incidence of MRI-related complications in pediatric and CHD patients with CIEDs, including epicardial and/or abandoned leads.

METHODS

A multicenter retrospective review included patients with CIEDs who underwent any MRI between 2007 and 2022 at congenital cardiac centers. The primary outcome was any patient adverse event or clinically significant CIED change after MRI, defined as pacing lead capture threshold increase >0.5 V with output change, P- or R- wave amplitude decrease >50% with sensitivity change, or impedance change >50%.

RESULTS

Across 14 institutions, 314 patients (median age 18.8 [1.3; 31.4] years) underwent 389 MRIs. There were 288 pacemakers (74%) and 87 implantable cardioverter-defibrillators (22%); 52% contained epicardial leads, and 14 (4%) were abandoned leads only. Symptoms or CIED changes occurred in 4.9% of MRI scans (6.1% of patients). On 9 occasions (2%), warmth or pain occurred. Pacing capture threshold or lead impedance changes occurred in 1.4% and 2.0% of CIEDs post-MRI and at follow-up.

CONCLUSION

Our data provide evidence that MRIs can be performed in pediatric and CHD patients with CIEDs, including non-MRI-conditional CIEDs and epicardial and/or abandoned leads, with rare minor symptoms or CIED changes but no other complications.

Modifying the trajectory of epicardial leads can substantially reduce MRI-induced RF heating in pediatric patients with a cardiac implantable electronic device at 1.5T

PURPOSE

After epicardial cardiac implantable electronic devices are implanted in pediatric patients, they become ineligible to receive MRI exams due to an elevated risk of RF heating. We investigated whether simple modifications in the trajectories of epicardial leads could substantially and reliably reduce RF heating during MRI at 1.5 T, with benefits extending to abandoned leads.

METHODS

Electromagnetic simulations were performed to assess RF heating of two common 35-cm epicardial lead trajectories exhibiting different degrees of coupling with MRI incident electric fields. Experiments in anthropomorphic phantoms implanted with commercial cardiac implantable electronic devices confirmed the findings. Both electromagnetic simulations and experimental measurements were performed using head-first and feet-first positioning and various landmarks. Transfer function approach was used to assess the performance of suggested modifications in realistic body models.

RESULTS

Simulations (head-first, chest landmark) of a 35-cm epicardial lead with a trajectory where the excess length of the lead was looped and placed on the inferior surface of the heart showed an 87-fold reduction in the 0.1 g-averaged specific absorption rate compared with the lead where the excess length was looped on the anterior surface. Repeated experiments with a commercial epicardial device confirmed this. For fully implanted systems following low-specific absorption rate trajectories, there was a 16-fold reduction in the average temperature rise and a 28-fold reduction for abandoned leads. The transfer function method predicted a 7-fold reduction in the RF heating in 336 realistic scenarios.

CONCLUSION

Surgical modification of epicardial lead trajectory can substantially reduce RF heating at 1.5 T, with benefits extending to abandoned leads.

Prediction of Sudden Death Risk in Patients with Congenital Heart Diseases

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

Clinical presentation of calmodulin mutations: the International Calmodulinopathy Registry

AIMS

Calmodulinopathy due to mutations in any of the three CALM genes (CALM1-3) causes life-threatening arrhythmia syndromes, especially in young individuals. The International Calmodulinopathy Registry (ICalmR) aims to define and link the increasing complexity of the clinical presentation to the underlying molecular mechanisms.

METHODS AND RESULTS

The ICalmR is an international, collaborative, observational study, assembling and analysing clinical and genetic data on CALM-positive patients. The ICalmR has enrolled 140 subjects (median age 10.8 years [interquartile range 5-19]), 97 index cases and 43 family members. CALM-LQTS and CALM-CPVT are the prevalent phenotypes. Primary neurological manifestations, unrelated to post-anoxic sequelae, manifested in 20 patients. Calmodulinopathy remains associated with a high arrhythmic event rate (symptomatic patients, n = 103, 74%). However, compared with the original 2019 cohort, there was a reduced frequency and severity of all cardiac events (61% vs. 85%; P = .001) and sudden death (9% vs. 27%; P = .008). Data on therapy do not allow definitive recommendations. Cardiac structural abnormalities, either cardiomyopathy or congenital heart defects, are present in 30% of patients, mainly CALM-LQTS, and lethal cases of heart failure have occurred. The number of familial cases and of families with strikingly different phenotypes is increasing.

CONCLUSION

Calmodulinopathy has pleiotropic presentations, from channelopathy to syndromic forms. Clinical severity ranges from the early onset of life-threatening arrhythmias to the absence of symptoms, and the percentage of milder and familial forms is increasing. There are no hard data to guide therapy, and current management includes pharmacological and surgical antiadrenergic interventions with sodium channel blockers often accompanied by an implantable cardioverter-defibrillator.

Age Matters: A Comparative Study of RF Heating of Epicardial and Endocardial Electronic Devices in Pediatric and Adult Phantoms during Cardiothoracic MRI

This study focused on the potential risks of radiofrequency-induced heating of cardiac implantable electronic devices (CIEDs) in children and adults with epicardial and endocardial leads of varying lengths during cardiothoracic MRI scans. Infants and young children are the primary recipients of epicardial CIEDs, though the devices have not been approved as MR conditional by the FDA due to limited data, leading to pediatric hospitals either refusing the MRI service to most pediatric CIED patients or adopting a scan-all strategy based on results from adult studies. The study argues that risk-benefit decisions should be made on an individual basis. We used 120 clinically relevant epicardial and endocardial device configurations in adult and pediatric anthropomorphic phantoms to determine the temperature rise during RF exposure at 1.5 T. The results showed that there was significantly higher RF heating of epicardial leads than endocardial leads in the pediatric phantom, but not in the adult phantom. Additionally, body size and lead length significantly affected RF heating, with RF heating up to 12 °C observed in models based on younger children with short epicardial leads. The study provides evidence-based knowledge on RF-induced heating of CIEDs and highlights the importance of making individual risk-benefit decisions when assessing the potential risks of MRI scans in pediatric CIED patients.

Trans-2,3-enoyl-CoA reductase-like-related catecholaminergic polymorphic ventricular tachycardia with regular ventricular tachycardia and response to flecainide

INTRODUCTION

We describe a unique case of TECRL-CPVT presented with cardiac arrest.

METHODS

Post resuscitation, the patient developed regular ventricular tachycardia featuring a left purkinje system morphology.

RESULTS

There was clear suppression of arrhythmia with the addition of flecainide and isolated ventricular ectopy causing secondary T-wave changes.

CONCLUSION

A high index of suspicion was required to eventually make the diagnosis through whole exome sequencing.

RF-induced heating of capped and uncapped abandoned epicardial leads during MRI at 1.5 T and 3 T

There is a paucity of data regarding the safety of magnetic resonance imaging (MRI) in patients with abandoned epicardial leads. Few studies have reported temperature rises up to 76 °C during MRI at 1.5 T in gel phantoms implanted with epicardial leads; however, lead trajectories used in these experiments were not clinically relevant. This work reports patient-specific RF heating of both capped and uncapped abandoned epicardial lead configurations during MRI at both 1.5 T and 3 T field strengths. We found that leads routed along realistic, patient-derived trajectories generated substantially lower RF heating than the previously reported worst-case phantom experiments. We also found that MRI at the head imaging landmark leads to substantially lower RF heating compared to MRI at the chest or abdomen landmarks at both 1.5 T and 3 T. Our results suggest that patients with abandoned epicardial leads may safely undergo MRI for head imaging, but caution is warranted during chest and abdominal imaging.Clinical Relevance- Patients with abandoned epicardial leads may safely undergo MRI for head imaging, but caution is warranted during chest and abdominal imaging.

Natural history of TANGO2 deficiency disorder: Baseline assessment of 73 patients

PURPOSE

TANGO2 deficiency disorder (TDD), an autosomal recessive disease first reported in 2016, is characterized by neurodevelopmental delay, seizures, intermittent ataxia, hypothyroidism, and life-threatening metabolic and cardiac crises. The purpose of this study was to define the natural history of TDD.

METHODS

Data were collected from an ongoing natural history study of patients with TDD enrolled between February 2019 and May 2022. Data were obtained through phone or video based parent interviews and medical record review.

RESULTS

Data were collected from 73 patients (59% male) from 57 unrelated families living in 16 different countries. The median age of participants at the time of data collection was 9.0 years (interquartile range = 5.3-15.9 years, range = fetal to 31.8 years). A total of 24 different TANGO2 alleles were observed. Patients showed normal development in early infancy, with progressive delay in developmental milestones thereafter. Symptoms included ataxia, dystonia, and speech difficulties, typically starting between the ages of 1 to 3 years. A total of 46/71 (65%) patients suffered metabolic crises, and of those, 30 (65%) developed cardiac crises. Metabolic crises were significantly decreased after the initiation of B-complex or multivitamin supplementation.

CONCLUSION

We provide the most comprehensive review of natural history of TDD and important observational data suggesting that B-complex or multivitamins may prevent metabolic crises.

The impact of damaging epilepsy and cardiac genetic variant burden in sudden death in the young

Background

Sudden unexpected death in children is a tragic event. Understanding the genetics of sudden death in the young (SDY) enables family counseling and cascade screening. The objective of this study was to characterize genetic variation in an SDY cohort using whole genome sequencing.

Methods

The SDY Case Registry is a National Institutes of Health/Centers for Disease Control surveillance effort to discern the prevalence, causes, and risk factors for SDY. The SDY Case Registry prospectively collected clinical data and DNA biospecimens from SDY cases <20 years of age. SDY cases were collected from medical examiner and coroner offices spanning 13 US jurisdictions from 2015-2019. The cohort included 211 children (mean age 1 year; range 0-20 years), determined to have died suddenly and unexpectedly and in whom DNA biospecimens and next-of-kin consent were ascertained. A control cohort consisted of 211 randomly sampled, sex-and ancestry-matched individuals from the 1000 Genomes Project. Genetic variation was evaluated in epilepsy, cardiomyopathy and arrhythmia genes in the SDY and control cohorts. American College of Medical Genetics/Genomics guidelines were used to classify variants as pathogenic or likely pathogenic. Additionally, genetic variation predicted to be damaging was identified using a Bayesian-based artificial intelligence (AI) tool.

Results

The SDY cohort was 42% European, 30% African, 17% Hispanic, and 11% with mixed ancestries, and 39% female. Six percent of the cohort was found to harbor a pathogenic or likely pathogenic genetic variant in an epilepsy, cardiomyopathy or arrhythmia gene. The genomes of SDY cases, but not controls, were enriched for rare, damaging variants in epilepsy, cardiomyopathy and arrhythmia-related genes. A greater number of rare epilepsy genetic variants correlated with younger age at death.

Conclusions

While damaging cardiomyopathy and arrhythmia genes are recognized contributors to SDY, we also observed an enrichment in epilepsy-related genes in the SDY cohort, and a correlation between rare epilepsy variation and younger age at death. These findings emphasize the importance of considering epilepsy genes when evaluating SDY.

Biventricular Assist Device Support for Intractable Arrhythmias From Histiocytoid Cardiomyopathy

Histiocytoid cardiomyopathy (HICMP) is a rare mitochondrial cardiomyopathy associated with recurrent life-threatening arrhythmias and variable degrees of systolic dysfunction. Successful heart transplantation for HICMP has been described, but there has been no published experience with biventricular assist device (BiVAD) support for intractable arrhythmias in HICMP. We report a 13 month old girl with left ventricular noncompaction and preserved systolic function who presented in cardiogenic shock secondary to incessant ventricular arrhythmias. After failed attempts at chemical and electrical cardioversion, she underwent BiVAD implantation as bridge to transplantation. Her BiVAD course was complicated by mechanical inflow obstruction during sinus rhythm, necessitating left-sided cannulation revision from an apical to atrial inflow cannula. This maneuver resolved the obstruction and the patient was transitioned to Berlin EXCOR (Berlin Heart Inc, The Woodlands, TX) BiVADs. On Berlin pumps, she had intermittent pauses (no fill/no eject) while in sinus rhythm, felt to be due to competition from intrinsic ejection. Despite these pauses, the patient experienced an uneventful remainder of her BiVAD course (205 days total) with minimal fibrin deposition and no device-related complications. BiVAD can support pediatric patients with hemodynamically significant arrhythmias to transplantation. Atrial cannulation strategy may be preferred in cases of preserved systolic function, ventricular noncompaction, and frequent rhythm changes.

Cardiac crises: Cardiac arrhythmias and cardiomyopathy during TANGO2 deficiency related metabolic crises

BACKGROUND

TANGO2 deficiency disorder (TDD) is an autosomal recessive disease associated with metabolic crisis, lethal cardiac arrhythmias, and cardiomyopathy. Data regarding treatment, management, and outcomes of cardiac manifestations of TDD are lacking.

OBJECTIVE

The purpose of this study was to describe TDD-related cardiac crises.

METHODS

Retrospective multicenter chart review was made of TDD patients admitted with cardiac crises, defined as development of ventricular tachycardia (VT), cardiomyopathy, or cardiac arrest during metabolic crises.

RESULTS

Twenty-seven children were admitted for 43 cardiac crises (median age 6.4 years; interquartile range [IQR] 2.4-9.8 years) at 14 centers. During crisis, QTc prolongation occurred in all (median 547 ms; IQR 504-600 ms) and a type I Brugada pattern in 8 (26%). Arrhythmias included VT in 21 (78%), supraventricular tachycardia in 3 (11%), and heart block in 1 (4%). Nineteen patients (70%) developed cardiomyopathy, and 20 (74%) experienced a cardiac arrest. There were 10 deaths (37%), 6 related to arrhythmias. In 5 patients, recalcitrant VT occurred despite use of antiarrhythmic drugs. In 6 patients, arrhythmias were controlled after extracorporeal membrane oxygenation (ECMO) support; 5 of these patients survived. Among 10 patients who survived VT without ECMO, successful treatment included intravenous magnesium, isoproterenol, and atrial pacing in multiple cases and verapamil in 1 patient. Initiation of feeds seemed to decrease VT events.

CONCLUSION

TDD-related cardiac crises are associated with a high risk of arrhythmias, cardiomyopathy, cardiac arrest, and death. Although further studies are needed, early recognition and appropriate treatment are critical. Acutely, intravenous magnesium, isoproterenol, atrial pacing, and ECMO as a last resort seem to be the best current treatment options, and early initiation of feeds may prevent VT events.

Interpersonal comparison among caregivers of children with asthma

Objective: We examined the extent to which caregivers of children with asthma used interpersonal comparisons-a novel comparison process that parallels social comparison and temporal comparison-to form judgments about their child. Methods & Measures: Using semi-structured interviews adapted from the McGill Illness Narrative Interview, we examined the interpersonal comparisons that caregivers of a child with asthma (n = 41) made regarding their child. Results: Interpersonal comparisons influenced caregiver thoughts, feelings, and behavior. They helped caregivers distinguish asthma from other breathing problems, evaluate the severity of the asthma, and understand their child's experience. However, they also created uncertainty by highlighting the complex, unpredictable nature of asthma. Interpersonal comparisons were a source of gratitude and hope, but also worry and frustration. Finally, interpersonal comparisons influenced caregivers' decisions and actions, resulting in decisions that aligned with and, at times, ran counter to biomedical models of asthma care. In some instances, caregivers used interpersonal comparisons to motivate their child's behavior. Conclusion: The interpersonal comparisons served as a source of information for caregivers trying to understand and manage their child's asthma. Investigating these comparisons also expands how we think about other comparison theories.

A comparative study of MRI-induced RF heating in pediatric and adult populations with epicardial and endocardial implantable electronic devices

Patients with congenital heart defects, inherited arrhythmia syndromes, and congenital disorders of cardiac conduction often receive a cardiac implantable electronic device (CIED). At least 75% of patients with CIEDs will need magnetic resonance imaging (MRI) during their lifetime. In 2011, the US Food and Drug Administration approved the first MR-conditional CIEDs for patients with endocardial systems, in which leads are passed through the vein and affixed to the endocardium. The majority of children, however, receive an epicardial CIED, where leads are directly sewn to the epicardium. Unfortunately, an epicardial CIED is a relative contraindication to MRI due to the unknown risk of RF heating. In this work, we performed anthropomorphic phantom experiments to investigate differences in RF heating between endocardial and epicardial leads in both pediatric and adult-sized phantoms, where adult endocardial CIED was the control. Clinical Relevance-This work provides a quantitative comparison of MRI RF heating of epicardial and endocardial leads in pediatric and adult populations.

The Position and Orientation of the Pulse Generator Affects MRI RF Heating of Epicardial Leads in Children

Infants and children with congenital heart defects often receive a cardiac implantable electronic device (CIED). Because transvenous access to the heart is difficult in patients with small veins, the majority of young children receive epicardial CIEDs. Unfortunately, however, once an epicardial CIED is placed, patients are no longer eligible to receive magnetic resonance imaging (MRI) exams due to the unknown risk of MRI-induced radiofrequency (RF) heating of the device. Although many studies have assessed the role of device configuration in RF heating of endocardial CIEDs in adults, such case for epicardial devices in pediatric patients is relatively unexplored. In this study, we evaluated the variation in RF heating of an epicardial lead due to changes in the lateral position and orientation of the implantable pulse generator (IPG). We found that changing the orientation and position of the IPG resulted in a five-fold variation in the RF heating at the lead's tip. Maximum heating was observed when the IPG was moved to a left lateral abdominal position of patient, and minimum heating was observed when the IPG was positioned directly under the heart. Clinical Relevance- This study examines the role of device configuration on MRI-induced RF heating of an epicardial CIED in a pediatric phantom. Results could help pediatric cardiac surgeons to modify device implantation to reduce future risks of MRI in patients.

Family Screening After Sudden Death in a Population-Based Study of Children

In a US population-based registry of sudden death in the young, this study performed familial evaluation of surviving relatives.

Practitioners' Confidence and Desires for Education in Cardiovascular and Sudden Cardiac Death Genetics

Background

Educating cardiologists and health care professionals about cardiovascular genetics and genetic testing is essential to improving diagnosis and management of patients with inherited cardiomyopathies and arrhythmias and those at higher risk for sudden cardiac death. The aim of this study was to understand cardiology and electrophysiology practitioners’ current practices, confidence, and knowledge surrounding genetic testing in cardiology and desired topics for an educational program.

Methods and Results

A one‐time survey was administered through purposive email solicitation to 131 cardiology practitioners in the United States. Of these, 107 self‐identified as nongenetic practitioners. Over three quarters of nongenetic practitioners reported that they refer patients to genetic providers to discuss cardiovascular genetic tests (n=82; 76.6%). More than half of nongenetic practitioners reported that they were not confident about the types of cardiovascular genetic testing available (n=60; 56%) and/or in ordering appropriate cardiovascular genetic tests (n=66; 62%). In addition, 45% (n=22) of nongenetic practitioners did not feel confident making cardiology treatment recommendations based on genetic test results. Among all providers, the most desired topics for an educational program were risk assessment (94%) and management of inherited cardiac conditions based on guidelines (91%).

Conclusions

This study emphasizes the importance of access to genetics services in the cardiology field and the need for addressing the identified deficit in confidence and knowledge about cardiogenetics and genetic testing among nongenetic providers. Additional research is needed, including more practitioners from underserved areas.

Genotype and Cardiac Outcomes in Pediatric Dilated Cardiomyopathy

Background

Pediatric dilated cardiomyopathy (DCM) is a well‐known clinical entity; however, phenotype–genotype correlations are inadequately described. Our objective was to provide genotype associations with life‐threatening cardiac outcomes in pediatric DCM probands.

Methods and Results

We performed a retrospective review of children with DCM at a large pediatric referral center (2007–2016), excluding syndromic, chemotherapy‐induced, and congenital heart disease causes. Genetic variants were adjudicated by an expert panel and an independent clinical laboratory. In a cohort of 109 pediatric DCM cases with a mean age at diagnosis of 4.2 years (SD 5.9), life‐threatening cardiac outcomes occurred in 47% (42% heart transplant, 5% death). One or more pathogenic/likely pathogenic variants were present in 40/109 (37%), and 36/44 (82%) of pathogenic/likely pathogenic variants occurred in sarcomeric genes. The frequency of pathogenic/likely pathogenic variants was not different in patients with familial cardiomyopathy (15/33 with family history versus 25/76 with no family history, P=0.21). TTN truncating variants occurred in a higher percentage of children diagnosed as teenagers (26% teenagers versus 6% younger children, P=0.01), but life‐threatening cardiac outcomes occurred in both infants and teenagers with these TTN variants. DCM with left ventricular noncompaction features occurred in 6/6 patients with MYH7 variants between amino acids 1 and 600.

Conclusions

Sarcomeric variants were common in pediatric DCM. We demonstrated genotype‐specific associations with age of diagnosis and cardiac outcomes. In particular, MYH7 had domain‐specific association with DCM with left ventricular noncompaction features. Family history did not predict pathogenic/likely pathogenic variants, reinforcing that genetic testing should be considered in all children with idiopathic DCM.