Conduction abnormalities in pediatric patients with restrictive cardiomyopathy

Diagnosis and Management of Rare Cardiomyopathies in Adult and Paediatric Patients. A Position Paper of the Italian Society of Cardiology (SIC) and Italian Society of Paediatric Cardiology (SICP)

Cardiomyopathies (CMPs) are myocardial diseases in which the heart muscle is structurally and functionally abnormal in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality. Thought for a long time to be rare diseases, it is now clear that most of the CMPs can be easily observed in clinical practice. However, there is a group of specific heart muscle diseases that are rare in nature whose clinical/echocardiographic phenotypes resemble those of the four classical morphological subgroups of hypertrophic, dilated, restrictive, arrhythmogenic CMPs. These rare CMPs, often but not solely diagnosed in infants and paediatric patients, should be more properly labelled as specific CMPs. Emerging consensus exists that these conditions require tailored investigation and management. Indeed, an appropriate understanding of these conditions is mandatory for early treatment and counselling. At present, however, the multisystemic and heterogeneous presentation of these entities is a challenge for clinicians, and time delay in diagnosis is a significant concern. The aim of this paper is to define practical recommendations for diagnosis and management of the rare CMPs in paediatric or adult age. A modified Delphi method was adopted to grade the recommendations proposed by each member of the writing committee.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients: Developed in collaboration with and endorsed by the Heart Rhythm Society (HRS), the American College of Cardiology (ACC), the American Heart Association (AHA), and the Association for European Paediatric and Congenital Cardiology (AEPC) Endorsed by the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS)

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consenus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology, (ACC) and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate follow-up in pediatric patients.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

Pediatric Restrictive Cardiomyopathies

Restrictive cardiomyopathy (RCM) is the least frequent phenotype among pediatric heart muscle diseases, representing only 2.5-3% of all cardiomyopathies diagnosed during childhood. Pediatric RCM has a poor prognosis, high incidence of pulmonary hypertension (PH), thromboembolic events, and sudden death, is less amenable to medical or surgical treatment with high mortality rates. In this scenario, heart transplantation remains the only successful therapeutic option. Despite a shared hemodynamic profile, characterized by severe diastolic dysfunction and restrictive ventricular filling, with normal ventricle ejection fraction and wall thickness, RCM recognizes a broad etiological spectrum, consisting of genetic/familial and acquired causes, each of which has a distinct pathophysiology and natural course. Hence, the aim of this review is to cover the causes, clinical presentation, diagnostic evaluation, treatment, and prognosis of pediatric RCM.

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.

Cardiomyopathies in children: classification, diagnosis and treatment

PURPOSE OF REVIEW

Cardiomyopathies are rare in the pediatric population, but significantly impact on morbidity and mortality. The present review aims to provide an overview of cardiomyopathies in children and some practical guidelines for their prognostic stratification and management.

RECENT FINDINGS

Pediatric cardiomyopathies may present as isolated cardiac muscle disease or in the context of complex clinical syndromes. The etiologic characterization represents an important step in the diagnosis and treatment of cardiomyopathies because of its impact on prognosis and on therapeutic measures. Indeed, replacement therapy is nowadays widely available and changes the natural history of the disease. More complex is the management of isolated cardiomyopathies, which lack specific therapies, mainly aimed at symptomatic relief. In this context, heart transplantation shows excellent outcomes in children, but wait-list mortality is still very high. Device therapy for sudden cardiac death prevention and the use of mechanical assist devices are becoming more common in the clinical practice and may help to reduce mortality.

SUMMARY

Providing insight into pediatric cardiomyopathies classification helps in the prognostication and management of such diseases. Recent years witnessed a significant improvement in mortality, but future research is still needed to improve quality of life and life expectations in the pediatric population.

Genetics of inherited cardiomyopathies in Africa

In sub-Saharan Africa (SSA), the burden of noncommunicable diseases (NCDs) is rising disproportionately in comparison to the rest of the world, affecting urban, semi-urban and rural dwellers alike. NCDs are predicted to surpass infections like human immunodeficiency virus, tuberculosis and malaria as the leading cause of mortality in SSA over the next decade. Heart failure (HF) is the dominant form of cardiovascular disease (CVD), and a leading cause of NCD in SSA. The main causes of HF in SSA are hypertension, cardiomyopathies, rheumatic heart disease, pericardial disease, and to a lesser extent, coronary heart disease. Of these, the cardiomyopathies deserve greater attention because of the relatively poor understanding of mechanisms of disease, poor outcomes and the disproportionate impact they have on young, economically active individuals. Morphofunctionally, cardiomyopathies are classified as dilated, hypertrophic, restrictive and arrhythmogenic; regardless of classification, at least half of these are inherited forms of CVD. In this review, we summarise all studies that have investigated the incidence of cardiomyopathy across Africa, with a focus on the inherited cardiomyopathies. We also review data on the molecular genetic underpinnings of cardiomyopathy in Africa, where there is a striking lack of studies reporting on the genetics of cardiomyopathy. We highlight the impact that genetic testing, through candidate gene screening, association studies and next generation sequencing technologies such as whole exome sequencing and targeted resequencing has had on the understanding of cardiomyopathy in Africa. Finally, we emphasise the need for future studies to fill large gaps in our knowledge in relation to the genetics of inherited cardiomyopathies in Africa.

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.

Double missense mutations in cardiac myosin-binding protein C and myopalladin genes: A case report with diffuse coronary disease, complete atrioventricular block, and progression to dilated cardiomyopathy

Cardiomyopathies caused by double gene mutations are rare but conferred a remarkably increased risk of end-stage progression, arrhythmias, and poor outcome. Compound genetic mutations leading to complex phenotype in the setting of cardiomyopathies represent an important challenge in clinical practice, and genetic tests allow risk stratification and personalized clinical management of patients. We report a case of a 50-year-old woman with congestive heart failure characterized by dilated cardiomyopathy, diffuse coronary disease, complete atrioventricular block, and missense mutations in cardiac myosin-binding protein C (MYBPC3) and myopalladin (MYPN). We discuss the plausible role of genetic profile in phenotype determination.

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.

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

Background

Our 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.

Methods

Twelve 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.

Results

A 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.

Conclusions

This study indicates that Ca²⁺ desensitizing green tea extract catechin, is helpful in correcting the impaired relaxation in pediatric cardiomyopathy patients with diastolic dysfunction.

Electronic supplementary material

The online version of this article (10.1186/s12929-019-0528-7) contains supplementary material, which is available to authorized users.

Contemporary Outcomes of Pediatric Restrictive Cardiomyopathy: A Single-Center Experience

BACKGROUND

Pediatric restrictive cardiomyopathy (RCM) has high mortality in historical cohorts, and traditional management often involves early referral for heart transplantation (HTx). This study sought to determine outcomes of pediatric RCM at a center that has favored medical management over early listing for HTx.

METHODS

All patients (N = 43) with pure RCM phenotype (RCM, N = 26) and hypertrophic cardiomyopathy with restrictive physiology (RCM/HCM, N = 17) managed at our center over a 15-year period were investigated. Outcomes of those listed for HTx (N = 18) were compared to a benchmark of contemporaneous pediatric RCM patients in the UNOS database (N = 377). Proportional hazards models were used to determine predictors of adverse outcomes.

RESULTS

The mean age was 11 ± 9 years and 49% were male. 14 of 18 patients listed received HTx. Overall mortality (12%) was identical between the phenotypes; however, RCM patients were more likely to be listed (P = 0.001) and receive HTx (P = 0.02) compared to RCM/HCM. Prior to HTx, 60% had documented arrhythmia, 16% had cardiac arrest, and 7% required mechanical circulatory support. 4 of 17 patients with an ICD/PM received device therapies (four of five shocks appropriate for VT/VF, and two effective anti-tachycardia pacing interventions). Outcomes of those listed for HTx at our center were similar to the UNOS benchmark. In multivariate analysis, markers of congestive heart failure were associated with adverse outcomes.

CONCLUSION

Heart failure and arrhythmia treatments can delay or possibly prevent the need for HTx in some cases of pediatric RCM. Survival post-HTx is not compromised using this approach.

Cardiopulmonary Resuscitation in Infants and Children With Cardiac Disease: A Scientific Statement From the American Heart Association

Cardiac arrest occurs at a higher rate in children with heart disease than in healthy children. Pediatric basic life support and advanced life support guidelines focus on delivering high-quality resuscitation in children with normal hearts. The complexity and variability in pediatric heart disease pose unique challenges during resuscitation. A writing group appointed by the American Heart Association reviewed the literature addressing resuscitation in children with heart disease. MEDLINE and Google Scholar databases were searched from 1966 to 2015, cross-referencing pediatric heart disease with pertinent resuscitation search terms. The American College of Cardiology/American Heart Association classification of recommendations and levels of evidence for practice guidelines were used. The recommendations in this statement concur with the critical components of the 2015 American Heart Association pediatric basic life support and pediatric advanced life support guidelines and are meant to serve as a resuscitation supplement. This statement is meant for caregivers of children with heart disease in the prehospital and in-hospital settings. Understanding the anatomy and physiology of the high-risk pediatric cardiac population will promote early recognition and treatment of decompensation to prevent cardiac arrest, increase survival from cardiac arrest by providing high-quality resuscitations, and improve outcomes with postresuscitation care.

A reappraisal of the mechanisms underlying the cardiac complications of sickle cell anemia

Anemia, hemolysis-driven vasculopathy, and intrinsic myocardial injury have been proposed as predisposing factors to cardiac disease in sickle cell anemia (SCA). The individual impact of these mechanisms on the cardiac features of SCA and the way they influence complications such as sudden death and dysrhythmias have been unclear. Recent findings of an acquired restrictive SCA-related cardiomyopathy, driven by myocardial fibrosis, may explain some of these cardiac features. Given the complexity of cardiac pathology in SCA, using additional parameters to tricuspid regurgitant jet velocity (left atrial volume, diastolic parameters, NT-proBNP) may improve the accuracy of noninvasive screening for cardiopulmonary complications in SCA.

Pediatric Cardiomyopathies

Pediatric cardiomyopathies are rare diseases with an annual incidence of 1.1 to 1.5 per 100 000. Dilated and hypertrophic cardiomyopathies are the most common; restrictive, noncompaction, and mixed cardiomyopathies occur infrequently; and arrhythmogenic right ventricular cardiomyopathy is rare. Pediatric cardiomyopathies can result from coronary artery abnormalities, tachyarrhythmias, exposure to infection or toxins, or secondary to other underlying disorders. Increasingly, the importance of genetic mutations in the pathogenesis of isolated or syndromic pediatric cardiomyopathies is becoming apparent. Pediatric cardiomyopathies often occur in the absence of comorbidities, such as atherosclerosis, hypertension, renal dysfunction, and diabetes mellitus; as a result, they offer insights into the primary pathogenesis of myocardial dysfunction. Large international registries have characterized the epidemiology, cause, and outcomes of pediatric cardiomyopathies. Although adult and pediatric cardiomyopathies have similar morphological and clinical manifestations, their outcomes differ significantly. Within 2 years of presentation, normalization of function occurs in 20% of children with dilated cardiomyopathy, and 40% die or undergo transplantation. Infants with hypertrophic cardiomyopathy have a 2-year mortality of 30%, whereas death is rare in older children. Sudden death is rare. Molecular evidence indicates that gene expression differs between adult and pediatric cardiomyopathies, suggesting that treatment response may differ as well. Clinical trials to support evidence-based treatments and the development of disease-specific therapies for pediatric cardiomyopathies are in their infancy. This compendium summarizes current knowledge of the genetic and molecular origins, clinical course, and outcomes of the most common phenotypic presentations of pediatric cardiomyopathies and highlights key areas where additional research is required.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT02549664 and NCT01912534.

Utility of Echocardiography in the Assessment of Left Ventricular Diastolic Function and Restrictive Physiology in Children and Young Adults with Restrictive Cardiomyopathy: A Comparative Echocardiography-Catheterization Study

The aim of the study is to determine the utility of echocardiography in the assessment of diastolic function in children and young adults with restrictive cardiomyopathy (RCM). RCM is a rare disease with high mortality requiring frequent surveillance. Accurate, noninvasive echocardiographic measures of diastolic function may reduce the need for invasive catheterization. Single-center, prospective, observational study of pediatric and young adult RCM patients undergoing assessment of diastolic parameters by simultaneous transthoracic echocardiogram (TTE) and invasive catheterization. Twenty-one studies in 15 subjects [median (IQR) = 13.8 years (7.0-19.2), 60% female] were acquired with median left ventricular end-diastolic pressure (LVEDP) 21 (IQR 18-25) mmHg. TTE parameters of diastolic function, including pulmonary vein A wave duration (r _s  = 0.79) and indexed left atrial volume (r _s  = 0.49), demonstrated significant positive correlation, while mitral valve A (r _s  = -0.44), lateral e' (r _s  = -0.61) and lateral a' (r _s  = -0.61) velocities showed significant negative correlation with LVEDP. Lateral a' velocity (≤0.042 m/s) and pulmonary vein A wave duration (≥156 m/s) both had sensitivity and specificity ≥80% for LVEDP ≥ 20 mmHg. In pediatric and young adult patients with RCM, lateral a' velocity and pulmonary vein A wave duration predicted elevated LVEDP with high sensitivity and specificity; however, due to technical limitations the latter was reliably measured in 12/21 patients. These noninvasive parameters may have utility in identifying patients that require further assessment with invasive testing. These findings require validation in a multicenter prospective cohort prior to widespread clinical implementation.

Cardiomyopathy With Restrictive Physiology in Sickle Cell Disease

OBJECTIVES

The aim of this study was to identify a unifying cardiac pathophysiology that explains the cardiac pathological features in sickle cell disease (SCD).

BACKGROUND

Cardiopulmonary complications, the leading cause of adult death in SCD, are associated with heart chamber dilation, diastolic dysfunction, elevated tricuspid regurgitant jet velocity (TRV), and pulmonary hypertension. However, no unifying cardiac pathophysiology has been identified to explain these findings.

METHODS

In a 2-part study, we first examined patients with SCD who underwent screening echocardiography during steady state at our institution. We then conducted a meta-analysis of cardiac studies in SCD.

RESULTS

In the 134 patients with SCD studied (median age 11 years), significant enlargement of the left atrial volume was present (z-score 3.1, p = 0.002), shortening fraction was normal (37.6 ± 4.7%), and lateral and septal ratios of mitral velocity to early diastolic velocity of the mitral annulus (E/e') were severely abnormal in 8% and 14% of patients, respectively, indicating impaired diastolic function. Both TRV and lateral E/e' correlated with enlarged left atrial volume in SCD (p = 0.003 and p = 0.006, respectively). Meta-analysis of 68 studies confirmed significant left atrial diameter enlargement in patients with SCD compared with controls, evidence of diastolic dysfunction and enlarged left ventricular end-diastolic dimension with normal shortening fraction. The majority of patients with catheter-confirmed pulmonary hypertension had mild pulmonary venous hypertension consistent with restrictive cardiac physiology.

CONCLUSIONS

Patients with SCD have a unique form of cardiomyopathy with restrictive physiology that is superimposed on hyperdynamic physiology and is characterized by diastolic dysfunction, left atrial dilation, and normal systolic function. This combination results in mild, secondary, pulmonary venous hypertension and elevated TRV. Sudden death is common in other forms of restrictive cardiomyopathy. Our finding of this unique restrictive cardiomyopathy may explain the increased mortality rates and sudden death seen in patients with SCD with mildly elevated TRV.

Clinical Characteristics and Treatment of Cardiomyopathies in Children

Cardiomyopathies are diseases of the heart muscle, a term introduced in 1957 to identify a group of myocardial diseases not attributable to coronary artery disease. The definition has since been modified to refer to structural and or functional abnormalities of the myocardium where other known causes of myocardial dysfunction, such as systemic hypertension, valvular disease and ischemic heart disease, have been excluded. In this review, we discuss the pathophysiology, clinical assessment and therapeutic strategies for hypertrophic, dilated and hypertrophic cardiomyopathies, with a particular focus on aspects unique to children.

Disturbance in Z-disk mechanosensitive proteins induced by a persistent mutant myopalladin causes familial restrictive cardiomyopathy

BACKGROUND

Familial restrictive cardiomyopathy (FRCM) has a poor prognosis due to diastolic dysfunction and restrictive physiology (RP). Myocardial stiffness, with or without fibrosis, underlie RP, but the mechanism(s) of restrictive remodeling is unclear. Myopalladin (MYPN) is a messenger molecule that links structural and gene regulatory molecules via translocation from the Z-disk and I-bands to the nucleus in cardiomyocytes. Expression of N-terminal MYPN peptide results in severe disruption of the sarcomere.

OBJECTIVES

The aim was to study a nonsense MYPN-Q529X mutation previously identified in the FRCM family in an animal model to explore the molecular and pathogenic mechanisms of FRCM.

METHODS

Functional (echocardiography, cardiac magnetic resonance [CMR] imaging, electrocardiography), morphohistological, gene expression, and molecular studies were performed in knock-in heterozygote (Mypn(WT/Q526X)) and homozygote mice harboring the human MYPN-Q529X mutation.

RESULTS

Echocardiographic and CMR imaging signs of diastolic dysfunction with preserved systolic function were identified in 12-week-old Mypn(WT/Q526X) mice. Histology revealed interstitial and perivascular fibrosis without overt hypertrophic remodeling. Truncated Mypn(Q526X) protein was found to translocate to the nucleus. Levels of total and nuclear cardiac ankyrin repeat protein (Carp/Ankrd1) and phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (Erk1/2), Erk1/2, Smad2, and Akt were reduced. Up-regulation was evident for muscle LIM protein (Mlp), desmin, and heart failure (natriuretic peptide A [Nppa], Nppb, and myosin heavy chain 6) and fibrosis (transforming growth factor beta 1, alpha-smooth muscle actin, osteopontin, and periostin) markers.

CONCLUSIONS

Heterozygote Mypn(WT/Q526X) knock-in mice develop RCM due to persistence of mutant Mypn(Q526X) protein in the nucleus. Down-regulation of Carp and up-regulation of Mlp and desmin appear to augment fibrotic restrictive remodeling, and reduced Erk1/2 levels blunt a hypertrophic response in Mypn(WT/Q526X) hearts.

Inherited cardiomyopathies

Cardiomyopathies (ie, diseases of the heart muscle) are major causes of morbidity and mortality. A significant percentage of patients with cardiomyopathies have genetic-based, inheritable disease and, over the past 2 decades the genetic causes of these disorders have been increasingly discovered. The genes causing these disorders when they are mutated appear to encode proteins that frame a "final common pathway" for that specific disorder, but the specifics of the phenotype, including age of onset, severity, and outcome is variable for reasons not yet understood. The "final common pathways" for the classified forms of cardiomyopathy include the sarcomere in the primarily diastolic dysfunction disorders hypertrophic cardiomyopathy and restrictive cardiomyopathy, the linkage of the sarcomere and sarcolemma in the systolic dysfunction disorder dilated cardiomyopathy, and the desmosome in arrhythmogenic cardiomyopathy. Left ventricular noncompaction cardiomyopathy (LVNC) is an overlap disorder and it appears that any of these "final common pathways" can be involved depending on the specific form of LVNC. The genetics and mechanisms responsible for these clinical phenotypes will be described.