Clinical profile and outcome of restrictive cardiomyopathy in children

Exploring TTN variants as genetic insights into cardiomyopathy pathogenesis and potential emerging clues to molecular mechanisms in cardiomyopathies

The giant protein titin (TTN) is a sarcomeric protein that forms the myofibrillar backbone for the components of the contractile machinery which plays a crucial role in muscle disorders and cardiomyopathies. Diagnosing TTN pathogenic variants has important implications for patient management and genetic counseling. Genetic testing for TTN variants can help identify individuals at risk for developing cardiomyopathies, allowing for early intervention and personalized treatment strategies. Furthermore, identifying TTN variants can inform prognosis and guide therapeutic decisions. Deciphering the intricate genotype-phenotype correlations between TTN variants and their pathologic traits in cardiomyopathies is imperative for gene-based diagnosis, risk assessment, and personalized clinical management. With the increasing use of next-generation sequencing (NGS), a high number of variants in the TTN gene have been detected in patients with cardiomyopathies. However, not all TTN variants detected in cardiomyopathy cohorts can be assumed to be disease-causing. The interpretation of TTN variants remains challenging due to high background population variation. This narrative review aimed to comprehensively summarize current evidence on TTN variants identified in published cardiomyopathy studies and determine which specific variants are likely pathogenic contributors to cardiomyopathy development.

Symptomatic presentation influences outcomes in pediatric restrictive cardiomyopathy

Introduction

Children with restrictive cardiomyopathy (RCM) traditionally have a poor prognosis, with most patients either dying or requiring heart transplantation within 2 years of diagnosis. The development of symptoms in RCM suggests advanced disease. However, as screening practices evolve and lead to diagnosis of early disease, identifying appropriate timing of transplant listing becomes increasingly important. In this context we compared outcomes of children with RCM presenting with clinical symptoms to those asymptomatic at initial presentation.

Methods

This retrospective cohort study included 25 patients with RCM presenting to a quaternary care center between 2001 and 2018. Times to transplantation, death, and a composite outcome of adverse cardiac events (CPR, cardioversion, inotropic support, mechanical ventilation, mechanical support, or heart transplant) were compared between those symptomatic and asymptomatic at presentation.

Results

At 2 years following diagnosis, patients asymptomatic at presentation had a significantly better transplant-free survival at 57% compared to 17% for symptomatic patients (p = 0.03). Those asymptomatic at diagnosis also had significantly improved cardiac event-free survival at 71% compared to symptomatic patients at 25% (p = 0.01). In multivariable analysis, cardiac symptoms at presentation remained an independent risk factor for heart-transplant or death [hazard ratio 5.17 (1.28-20.85), p = 0.02].

Conclusion

Patients with RCM who are symptomatic at time of diagnosis have significantly worse transplant-free survival and cardiac event-free survival. Given current practice variability in timing of transplant listing, the presence of any cardiac symptoms is an important negative prognostic marker and should prompt urgent transplant listing.

Outcomes of Restrictive Cardiomyopathy in Japanese Children - A Retrospective Cohort Study

BACKGROUND

There has been no nationwide survey on the prognosis of pediatric restrictive cardiomyopathy (RCM) in Japan; therefore, this retrospective multicentered study was designed to investigate the long-term survival rate of pediatric patients with RCM in Japan.Methods and Results:A multicentered, retrospective observational study was performed between 1990 and 2014 and included patients diagnosed with RCM who were aged <18 years from 18 Japanese institutions. A total of 54 patients were diagnosed with RCM. The median age at diagnosis was 4.4 years, and the median duration of observation was 2.2 years at the time of this study. Of these patients, 54% had symptoms, including heart failure. Twelve patients died without heart transplantation, mostly due to heart failure. The median time to death from diagnosis was 2.5 years. Freedom from death at 1, 5, and 10 years was 91%, 68%, and 62%, respectively. Death occurred within 5 years of diagnosis in most patients. Twenty-two patients underwent heart transplantation. Freedom from heart transplantation at 1, 5, and 10 years was 77%, 58%, and 53%, respectively. Freedom from death or heart transplantation at 1, 5, and 10 years was 72%, 40%, and 34%, respectively. The presence of symptoms was a risk factor for death or transplantation.

CONCLUSIONS

The prognosis of pediatric RCM is poor, and the heart transplantation rate is low in Japan.

Cardiomyocyte Dysfunction in Inherited Cardiomyopathies

Inherited cardiomyopathies form a heterogenous group of disorders that affect the structure and function of the heart. Defects in the genes encoding sarcomeric proteins are associated with various perturbations that induce contractile dysfunction and promote disease development. In this review we aimed to outline the functional consequences of the major inherited cardiomyopathies in terms of myocardial contraction and kinetics, and to highlight the structural and functional alterations in some sarcomeric variants that have been demonstrated to be involved in the pathogenesis of the inherited cardiomyopathies. A particular focus was made on mutation-induced alterations in cardiomyocyte mechanics. Since no disease-specific treatments for familial cardiomyopathies exist, several novel agents have been developed to modulate sarcomere contractility. Understanding the molecular basis of the disease opens new avenues for the development of new therapies. Furthermore, the earlier the awareness of the genetic defect, the better the clinical prognostication would be for patients and the better the prevention of development of the disease.

Cardiomyopathies: An Overview

Background: Cardiomyopathies are a heterogeneous group of pathologies characterized by structural and functional alterations of the heart. Aims: The purpose of this narrative review is to focus on the most important cardiomyopathies and their epidemiology, diagnosis, and management. Methods: Clinical trials were identified by Pubmed until 30 March 2021. The search keywords were “cardiomyopathies, sudden cardiac arrest, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy, arrhythmogenic cardiomyopathy (ARCV), takotsubo syndrome”. Results: Hypertrophic cardiomyopathy (HCM) is the most common primary cardiomyopathy, with a prevalence of 1:500 persons. Dilated cardiomyopathy (DCM) has a prevalence of 1:2500 and is the leading indication for heart transplantation. Restrictive cardiomyopathy (RCM) is the least common of the major cardiomyopathies, representing 2% to 5% of cases. Arrhythmogenic cardiomyopathy (ARCV) is a pathology characterized by the substitution of the myocardium by fibrofatty tissue. Takotsubo cardiomyopathy is defined as an abrupt onset of left ventricular dysfunction in response to severe emotional or physiologic stress. Conclusion: In particular, it has been reported that HCM is the most important cause of sudden death on the athletic field in the United States. It is needless to say how important it is to know which changes in the heart due to physical activity are normal, and when they are pathological.

Diagnostic value of P-waves in children with idiopathic restrictive cardiomyopathy

Restrictive cardiomyopathy (RCM) is a rare myocardial disease with an impaired diastolic function and poor prognosis. Almost all RCM patients are reported to have abnormal P-waves due to atrial overloading. This study aimed to reveal the characteristics of the P-waves in RCM patients and to suggest the diagnostic index of RCM in children with a 12-lead electrocardiogram (ECG). We retrospectively investigated 17 ECGs of children with idiopathic RCM during the initial visit at 15 institutes in Japan between 1979 and 2013. The RCM group was divided into four groups based on the age (elementary school [ES] and junior high school [JHS] students) and inception of the diagnosis (abnormal ECG on school-heart-screening [e-RCM] and some cardiovascular symptoms [s-RCM]), the ES/e-RCM (n = 5), ES/s-RCM (n = 4), JHS/e-RCM (n = 4), and JHS/s-RCM (n = 4) groups. As an aged-match control group, school-heart-screening ECGs of 1st-grade ES students (16,770 students) and 1st-grade JHS students (18,126 students) from Kagoshima in 2016 were adopted. For a comparison between the groups, we used the effect size "Hedge's g" by calculating the mean and standard deviation of the two groups. An effect size of 0.8 (or above) had an overlap of 53% (or less). The effect sizes of the sum of the absolute values of the forward and backward amplitudes in lead V1 (P1 + P2 V1) was the largest, and the ES/e-RCM, ES/s-RCM, JHS/e-RCM, and JHS/s-RCM were 15.8, 22.1, 9.4, and 10.3, respectively. A P1 + P2 V1 > 200 μV was able to rule in all RCM patients, thus, we proposed 200 µV as the cutoff value for screening purposes. In conclusion, the P1 + P2 V1 in the school-heart-screening may be useful for detecting asymptomatic or early-stage RCM in school-age children.

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.

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.

Idiopathic Restrictive Cardiomyopathy in Children and Young Adults

Idiopathic restrictive cardiomyopathy (IRC) is a rare condition characterized by reduced ventricular compliance. Children with IRC have poor outcomes with most patients proceeding to cardiac transplantation. We sought to analyze our institutional experience and assess contemporary outcomes for children with IRC. We reviewed the medical record for patients (<21 years old) evaluated for a primary diagnosis of IRC between 1975 and 2013 at our institution. Demographic, clinical, echocardiographic, and catheterization data were abstracted. The patients were divided into 2 groups comprising a historical cohort (HC) (diagnosis: 1975 to 1993, n = 8) and a contemporary cohort (CC) (diagnosis: 1994 to 2013, n = 12). Twenty children were identified with IRC (mean age at presentation 9.7 ± 6.5 years, 55% female). Mean length of follow-up was 6.5 ± 8.4 years (range 0.1 to 35.6 years). In the CC, 7 of 12 patients (58%) progressed to cardiac transplantation (mean age of 9 ± 4 years at transplant, mean interval from diagnosis of IRC: 1.5 ± 0.9 years). Overall survival was improved significantly in the CC compared with the HC (80% vs. 38%, p = 0.02), but transplantation free survival was no different between the CC and HC over 5 years (38% vs 38%, p = 0.65). In the CC, elevation of mitral valve Doppler E/e' ratio on echocardiography was associated with increased mortality (p = 0.01). In conclusion, IRC continues has a poor prognosis. Early referral for transplantation was associated with improved overall survival in the modern era. Patients with markedly elevated E/e' ratio may have increased risk of death.

Cardiomyopathy in the pediatric patients

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

Acute Ischemic Pediatric Stroke Management: An Extended Window for Mechanical Thrombectomy?

Ischemic stroke is a rare condition to afflict the pediatric population. Congenital cardiomyopathy represents one of several possible etiologies in children. We report a 9-year-old boy who developed right middle cerebral artery stroke secondary to primary restrictive cardiomyopathy. In the absence of pediatric guidelines, the child met adult criteria for mechanical thrombectomy given the small core infarct and large penumbra. The literature suggests children may benefit from mechanical thrombectomy in carefully selected cases. Our patient exemplifies specific circumstances in which acute stroke therapy with thrombolysis and thrombectomy may be safe.

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.

Successful Heart Transplantation Following Decompressive Craniectomy in a Patient with Restrictive Cardiomyopathy and Extensive Stroke in the Region of the Right Middle Cerebral Artery

Restrictive cardiomyopathy (RCM) in children is associated with a greater risk of embolic stroke than are other congenital heart diseases. After diagnosis, 50% of children with RCM die within 2 years without heart transplantation. As such, all RCM patients are placed on the heart transplantation list and must wait for an appropriate heart for transplantation. Every type of embolic stroke can occur while waiting for a donor heart; therefore, the cardiovascular team must initiate antithrombotic therapy at time RCM is diagnosed. Some pediatric RCM patients experience embolic stroke (50% are the cerebral type) despite antithrombotic therapy, including acetylsalicylic acid, warfarin, and heparine. Neurosurgeons working in hospitals that perform organ transplantation expect to see RCM cases with restrictive large cerebral infarct. We think that decompressive craniectomy should be performed as soon as possible after determining the clinical condition of any patient with RCM and a large right middle cerebral artery (MCA) infarct.

Spontaneously occurring restrictive nonhypertrophied cardiomyopathy in domestic cats: a new animal model of human disease

BACKGROUND

Spontaneously occurring small animal models of myocardial disease, closely resembling the human condition, have been reported for hypertrophic cardiomyopathy (in cats) and arrhythmogenic right ventricular cardiomyopathy (in cats and boxer dogs). Nonhypertrophied restrictive cardiomyopathy (RCM) is a well-recognized but relatively uncommon primary heart muscle disease causing substantial morbidity in humans. We describe RCM occurring in felines here as a potential model of human disease.

METHODS

We used two-dimensional and Doppler echocardiography to define morphologic and functional features of RCM in 35 domestic cats (25 male; 10±4 years old) presenting to a subspecialty veterinary clinic. Ten underwent complete necropsy examination. Echocardiographic parameters of diastolic filling were compared to those in 41 normal controls.

RESULTS

The 35 cats presented with congestive heart failure (n=32), lethargy (n=2), or syncope (n=1), associated with thromboembolism in 5 and supraventricular tachyarrhythmias in 8. During an average 4.4-year follow-up period, 18 died or were euthanized due to profound heart failure, and 3 died suddenly; survival from clinical presentation to death was 0.1 to 52 months. Echocardiographic and necropsy examination showed biatrial enlargement, nondilated ventricular chambers, and normal wall thicknesses and atrioventricular valves. Histopathology demonstrated disorganized myocyte architecture and patchy replacement myocardial fibrosis. Pulsed Doppler demonstrated restrictive physiology with increased early (E) mitral filling velocity (1.1±0.3 m/s) and peak E to peak late (A) flow ratios (4.3±1.2), reduced A filling velocity (0.3±0.1 m/s), and shortened mitral deceleration time (40.7±9.3 ms; all P<.001 vs. controls), with preserved left ventricular systolic function.

CONCLUSIONS

A primary myocardial disease occurring spontaneously in domestic cats is remarkably similar to restrictive nondilated and nonhypertrophied cardiomyopathy in man and represents another potential animal model for human disease.

Insights into restrictive cardiomyopathy from clinical and animal studies

Cardiomyopathies are diseases that primarily affect the myocardium, leading to serious cardiac dysfunction and heart failure. Out of the three major categories of cardiomyopathies (hypertrophic, dilated and restrictive), restrictive cardiomyopathy (RCM) is less common and also the least studied. However, the prognosis for RCM is poor as some patients dying in their childhood. The molecular mechanisms behind the disease development and progression are not very clear and the treatment of RCM is very difficult and often ineffective. In this article, we reviewed the recent progress in RCM research from the clinical studies and the translational studies done on diseased transgenic animal models. This will help for a better understanding of the mechanisms underlying the etiology and development of RCM and for the design of better treatments for the disease.

Clinicopathological features of fatal cardiomyopathy in childhood: an autopsy series

AIM

  Cardiomyopathy, a group of primary myocardial disorders, is an uncommon, but important, cause of death in childhood. This study examines the demographic, clinical and pathological features of fatal cardiomyopathy in childhood with particular reference to its classification and autopsy findings.

METHOD

  The method of this study was a retrospective structured review of all paediatric autopsies performed at a single specialist centre from 1995 to 2009 inclusive, in order to determine the demographic, clinical and pathological features of fatal cardiomyopathy.

RESULTS

  From a total of 2229 autopsies performed at the centre during the study period on live-born infants and children, 34 confirmed cases of cardiomyopathy were identified (1.5%). More than half (59%) of these cases occurred in infants (less than 1 year of age). Heart weight of cardiomyopathy cases was significantly greater than those with normal hearts (P < 0.001), and 77% had heart weights above the 95th percentile of the normal expected range for age, including all of those over 1 year age. Of cardiomyopathy cases, 50% were primary dilated cardiomyopathy and 27% were primary hypertrophic cardiomyopathy. Twelve of 34 cases (35%) presented as sudden unexpected death, the diagnosis of cardiomyopathy being only made at autopsy.

CONCLUSION

  Cardiomyopathy is an uncommon cause of death in infancy and childhood. It can present as sudden unexpected death and encompasses a range of aetiologies. Heart weight above the 95th percentile at autopsy is present in most cases but heart weight may be within the normal range in infants.

Outcomes of restrictive cardiomyopathy in childhood and the influence of phenotype: a report from the Pediatric Cardiomyopathy Registry

BACKGROUND

Restrictive cardiomyopathy (RCM) has been associated with poor prognosis in childhood. The goal of the present analysis was to use the Pediatric Cardiomyopathy Registry to analyze outcomes of childhood RCM, with a focus on the impact of phenotype comparing pure RCM with cases that have additional features of hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

We analyzed the Pediatric Cardiomyopathy Registry database (1990-2008; N=3375) for cases of RCM. Cases were defined as pure when RCM was the only assigned diagnosis. Additional documentation of HCM at any time was used as the criterion for RCM/HCM phenotype. RCM accounted for 4.5% of cases of cardiomyopathy. In 101 (66%), pure RCM was diagnosed; in 51 (34%), there was a mixed phenotype. Age at diagnosis was not different between groups, but 10% of the pure RCM group was diagnosed in infancy versus 24% of the RCM/HCM group. Freedom from death was comparable between groups with 1-, 2-, and 5-year survival of RCM 82%, 80%, and 68% versus RCM/HCM 77%, 74%, and 68%. Transplant-free survival was 48%, 34%, and 22% and 65%, 53%, and 43%, respectively (P=0.011). Independent risk factors at diagnosis for lower transplant-free survival were heart failure (hazard ratio 2.20, P=0.005), lower fractional shortening z score (hazard ratio 1.12 per 1 SD decrease in z score, P=0.014), and higher posterior wall thickness in the RCM/HCM group only (hazard ratio 1.32, P<0.001). Overall, outcomes were worse than for all other forms of cardiomyopathy.

CONCLUSIONS

Transplant-free survival is poor for RCM in childhood. Survival is independent of phenotype; however, the RCM/HCM phenotype has significantly better transplant-free survival.

CLINICAL TRIALS REGISTRATION

URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00005391.

Conduction abnormalities in pediatric patients with restrictive cardiomyopathy

BACKGROUND

Pediatric restrictive cardiomyopathy carries a poor prognosis secondary to a high risk of sudden death previously attributed to ventricular tachyarrhythmias. The extent of conduction abnormalities in this population and their relationship to life-threatening events has not been previously reported.

METHODS AND RESULTS

A retrospective study of pediatric patients with restrictive cardiomyopathy diagnosed between April 1994 and May 2011 was performed. Demographic, cardiac, and ECG characteristics and the mechanisms of serious arrhythmic events (death or episode of acute hemodynamic compromise thought to be secondary to arrhythmia) were evaluated. Sixteen patients (1-17 years of age) were reviewed, with 5 sudden cardiac events noted, including 4 deaths. Two deaths were caused by development of acute heart block; another patient with syncope had intermittent heart block and survived as the result of pacing features of an implanted defibrillator system. The median PR interval (222 versus 144 ms; P<0.01) and the QRS duration (111 versus 74; P=0.01) were significantly longer in those who had an acute cardiac event. Older age at presentation was associated with sudden cardiac events (P<0.01). No other functional or echocardiographic variables were associated with a sudden cardiac event.

CONCLUSIONS

Pediatric patients with restrictive cardiomyopathy are at risk for acute high-grade heart block, and, in this cohort, bradycardic events represented a significant portion of all arrhythmic events. Aggressive ECG monitoring strategies looking for conduction system disease should be ongoing in all patients with restrictive cardiomyopathy. Implantation of a defibrillator/pacemaker should be considered as prophylactic management.

Utility of Doppler tissue imaging-derived indices in identifying subclinical systolic ventricular dysfunction in children with restrictive cardiomyopathy

Restrictive cardiomyopathy (RCM) is characterized by irreversible diastolic dysfunction with preserved systolic function. The aim of this study was to investigate the presence of impaired ventricular contractility even in the presence of normal ejection fraction (EF) in children with RCM. Longitudinal Doppler tissue velocities were obtained from apical 4-chamber view at three locations--the left-ventricular (LV) lateral wall, the septum, and the right ventricle--in 8 children age 3-17 years old with RCM who had LV EF >55%. Peak systolic velocity (S'), acceleration during isovolumic contraction (IVA), and myocardial performance index (MPI) were measured. Data from the RCM group were compared with those from 24 age- and sex-matched controls. Both S' and IVA were markedly lower at the septum (S' 6.2 ± 1.7 vs. 9.2 ± 1.6, P < 0.001; IVA 1.8 ± 0.5 vs. 3.9 ± 1.5, P < 0.001). MPI, a measure of both diastolic and systolic function, was statistically significantly greater in the RCM group at all 3 locations (P < 0.005). S' and IVA identify global subclinical systolic dysfunction in RCM with normal EF. These findings suggest that pre-ejection abnormality and subclinical systolic dysfunction coexist with diastolic dysfunction in children with RCM.

Restrictive cardiomyopathy in childhood

Depending on the part of the world one lives in, restrictive cardiomyopathy is either one of the rarest forms of cardiomyopathy in childhood, with no cause usually identified, or it is secondary to a poorly understood disease, endomyocardial fibrosis, that is endemic in some populations. Regardless of the underlying cause, the outcome is poor once symptoms develop. This article reviews the definitions, epidemiology, etiologies, genetics, "overlap" phenotypes, clinical presentation, diagnostic evaluation, outcome, and management of pediatric patients with restrictive cardiomyopathy.

A case of restrictive cardiomyopathy presenting in fetal life with an isolated pericardial effusion

We describe the evolution during pregnancy of a case of restrictive cardiomyopathy which first presented at 22 weeks' gestation with a large pericardial effusion. Measurements of cardiac function were normal and remained near normal until late in the third trimester, when pulsed and tissue Doppler data suggested impairment in ventricular relaxation. This disease progressed in postnatal life to symptomatic restrictive cardiomyopathy by 2 years of age necessitating cardiac transplant. To our knowledge, this is the first time this unusual association has been reported.

Restrictive cardiomyopathy

BACKGROUND

Restrictive cardiomyopathy is characterized by ventricular diastolic dysfunction with a clinical course in childhood that is often progressive despite medical therapy.

METHODS

A review of the literature and clinical experience was used to summarize the natural history of this oftentimes devastating disease with a focus on diagnostic tools and therapeutic options.

RESULTS

The clinical presentation of restrictive cardiomyopathy can be highly variable, ranging from asymptomatic to overt signs of heart failure with pulmonary hypertension. Emerging noninvasive diagnostic tools are increasingly helpful yet there remains a role for invasive studies including cardiac catheterization with or without endomyocardial biopsy. A significant risk of sudden death exists and may not be limited to those with more pronounced symptoms.

CONCLUSIONS

Children with restrictive cardiomyopathy require comprehensive evaluation with careful surveillance. Early listing for cardiac transplantation should be considered.

Restrictive cardiomyopathy in a child

Restrictive cardiomyopathy in young children is rare and carries a poor prognosis. We report an 18-month-old girl with poor feeding and abdominal distension. Except for hepatomegaly, no other gastrointestinal abnormalities were found. She had normal-sized ventricles but biatrial enlargement. Echocardiography demonstrated normal systolic but impaired diastolic function. Cardiac catheterization revealed a characteristic dip-and-plateau configuration of the right ventricular pressure tracing. The diagnosis turned out to be typical restrictive cardiomyopathy. The patient was maintained on aspirin while awaiting cardiac transplant.

Pediatric restrictive cardiomyopathy associated with a mutation in beta-myosin heavy chain

Most children do not have a known cause of cardiomyopathy which limits the potential for disease-specific therapies. Of the different phenotypic presentations of cardiomyopathy, the restrictive form carries the poorest prognosis and has the lowest rate of identification of etiology. We present the first description of a beta-myosin heavy chain gene mutation in an infant with restrictive cardiomyopathy requiring cardiac transplantation. As demonstrated by three-dimensional protein structure modeling, the missense mutation is in a highly conserved amino acid at the critical binding region for the essential light chain. This case emphasizes that mutations in sarcomeric proteins, which are known to cause hypertrophic cardiomyopathy in adults, may be associated with the development of restrictive physiology in childhood. Identification of the genetic basis of pediatric cardiomyopathy has important implications for management and genetic counseling.

Fetal cardiomyopathy--in utero evaluation and clinical significance

OBJECTIVE

To describe the prenatal diagnosis and outcome of fetal cardiomyopathy (CM).

METHODS

The charts, photographs and videotapes of all fetuses with CM, who were assessed during pregnancy at two referral centers, were reviewed.

RESULTS

The diagnosis of CM was established in 12 fetuses. All had structurally normal hearts, and all cases were diagnosed after 23 weeks of gestation, following normal early fetal echocardiogram. Three clusters of fetal CM appeared: Familial--two sib fetuses of a mother, who is a second generation of CM. Both had dilated CM and pathological findings were consistent with the diagnosis of endocardial fibroelastosis. Secondary--CM that was induced by another factor. Idiopathic--six cases of CM without an underlying specific etiology. Three women elected to terminate their pregnancy. Among the nine who delivered, four had a favorable outcome with normal cardiac function at the age of 1 month, in which three belonged to the secondary category, and five cases were complicated by fetal/infant death.

CONCLUSIONS

CM may develop during fetal life and might be diagnosed by prenatal echocardiography. Normal cardiac findings in a midtrimester fetus do not exclude subsequent development of CM. Detailed prenatal sonographic examination may aid in determining the neonatal outcome.

Electrocardiographic and Clinical Characteristics of Idiopathic Restrictive Cardiomyopathy in Children

BACKGROUND

Idiopathic restrictive cardiomyopathy (RCM) is not a single disease and is rare.

METHODS AND RESULTS

The clinical features and clinical course of 12 pediatric patients with RCM seen between 1978 and 2005 were retrospectively analyzed. The age at diagnosis ranged from 4 months to 12 years (median 4 years). The age of 7 patients diagnosed because of an abnormal electrocardiogram (ECG) ranged from 4 to 12 years. Three infants less than 2 years old presented with cardiomegaly. Obliquely elevated ST-T segments and the late peak T waves on 12-lead ECG were present in 8 patients (67%). Three patients with ST depression during exercise had no perfusion defects on radioisotope myocardial perfusion imaging. Two patients underwent orthotopic heart transplantation. Of the remaining 10 patients, 7 have died: 4 died suddenly and 3 died of right heart failure. Three patients with a hypertrophic left ventricular wall had a prolonged survival. The probability of survival at 1, 2 and 3 years was 78%, 52% and 26%, respectively.

CONCLUSIONS

Obliquely elevated ST-T segments and the late peak T wave on ECG are characteristic, and reflect the restrictive physiology, which may indicate abnormalities of repolarization of ventricular muscle. The mode of death was either heart failure from pulmonary hypertension or sudden death from presumed ventricular arrhythmia.

Cardiac function assessment in patients with family history of nonhypertrophic cardiomyopathy: a prenatal and postnatal study

Nonobstructive cardiomyopathies (CMs) may be familial in 20â<euro>"55% of cases. Little is known about the role of fetal echocardiography in such cases. We evaluated the cardiac function serially pre- and postnatally in cases with a family history of nonobstructive CM. The fetal and postnatal studies were performed in the echocardiogarphy laboratory at a tertiary institution. Twenty-six cases from 16 families with a family history of CM were studied. Three fetal echocardiograms were performed at or near 18, 25, and 32 weeks of gestation for complete cardiac functional assessment. Postnatally clinical evaluation, electrocardiogram, and an echocardiogram were performed within the first 3 months, with serial reevaluation for those identified with CM. The mean follow-up was 46 +/- 9 months. Abnormal cardiac function was observed in 8 cases (30%). Six had a previously affected sibling, 1 had other family members affected, and 1 had both antecedents. Four had dilated CM diagnosed prenatally of which 1 recovered, 2 died in utero, and 1 died soon after birth. The remaining 4 had normal fetal echoes and were diagnosed with CM in the first 3 months of life. Three had dilated CM with recovery, and 1 had restrictive CM requiring cardiac transplantation. This study demonstrates a high familial recurrence rate of CM. Fetal echo is useful for early diagnosis, although a normal study does not preclude ventricular dysfunction at a later stage, justifying serial prenatal and postnatal evaluation. Early identification may expedite listing for transplantation.

Familial restrictive cardiomyopathy with skeletal abnormalities

A family is described in which 5 of 9 living children were found to have restrictive cardiomyopathy associated with skeletal muscle and orthopedic abnormalities. In the absence of another identifiable etiology, a genetic cause for restrictive cardiomyopathy in this family is probable. Consistent with the poor prognosis encountered for children with restrictive cardiomyopathy, 2 children in this family died, whereas a third was symptomatic by age 3 years.

Outcome of idiopathic restrictive cardiomyopathy in children

Eighteen children with idiopathic restrictive cardiomyopathy (IRC) were studied in an attempt to identify potential predictors of poor outcome. Four patients presented with low cardiac output (CO) syndrome. Fourteen remaining patients were minimally symptomatic at presentation but developed a low CO syndrome at a mean of 2.8 +/- 2.3 years after diagnosis. At the time of development of low CO in the 18 patients, mean left ventricular end-diastolic pressure was 27 mm Hg, right ventricular end-diastolic pressure was 18 mm Hg, cardiac index was 2.5 L/min/m(2), and pulmonary vascular resistance index (PVRI) was 8.8 U-m(2). Eleven of the 18 patients underwent cardiac transplantation. One died perioperatively from donor right-sided cardiac failure and 10 survived. Six were not transplanted and died, including 3 in whom transplantation was precluded secondary to extremely elevated PVRI. One patient is alive with right-sided cardiac failure. Ten of our 18 patients had pulmonary hypertension (PVRI >6 U-m(2)) at the time of referral for cardiac transplant and/or development of low CO syndrome. In comparison, children with dilated cardiomyopathy who were referred for heart transplant during the same time period had a PVRI that was significantly lower (5.2 U-m(2)). Elevated PVRI was associated with death (p <0.01) and 40% of our children with pulmonary hypertension were precluded from receiving an orthotopic heart transplant because their pulmonary hypertension was so severe. No risk factors for the development of pulmonary hypertension were identified; therefore, all children with IRC should undergo serial monitoring of their PVRI, and any increase should prompt a transplant evaluation.

Cardiomyopathy and heart transplantation in children

Cardiac transplantation has become a standard therapeutic option for certain disorders in which poor cardiac output without other surgical options exists in the face of maximized medical therapy. The most common disorder requiring transplantation is dilated cardiomyopathy, although other forms of cardiomyopathy (ie, restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia/cardiomyopathy, and hypertrophic cardiomyopathy with poor ventricular function) may require transplantation as well. In this review, the current indications and outcomes of heart transplantation in patients with cardiomyopathy are discussed.

Cardiac transplantation for pediatric restrictive cardiomyopathy: presentation, evaluation, and short-term outcome

BACKGROUND

Because of the poor prognosis of pediatric restrictive cardiomyopathy, transplantation has been proposed as the treatment of choice for this disease.

METHODS

We reviewed our experience with the presentation, evaluation, and short-term outcome in 8 pediatric patients with restrictive cardiomyopathy referred for transplantation. Potential reversibility of elevation in pulmonary vascular resistance was tested before transplantation with nitroprusside and nitric oxide, with follow-up cardiac catheterization performed 6 to 12 months after transplantation.

RESULTS

The mean age of diagnosis of restrictive cardiomyopathy was 6.3 years and the mean interval from diagnosis to referral for transplantation was 3.6 years. Elevation of pulmonary vascular resistance was common and tended to progress with longer follow-up. Three of the 8 patients had pulmonary vascular resistance indices greater than 10 Woods unit/m(2) and transpulmonary gradients greater than 20 mm Hg. The administration of nitroprusside and nitric oxide reversed elevated pulmonary resistance and transpulmonary gradients in all patients. Nitric oxide successfully reversed pulmonary vascular resistance in patients unresponsive to nitroprusside. All patients underwent successful transplantation and follow-up catheterization revealed normal pulmonary hemodynamics in each patient.

CONCLUSIONS

Pediatric restrictive cardiomyopathy can be associated with marked elevation in the pulmonary vascular resistance, which may contribute to the poor prognosis in these patients and potentially make cardiac transplantation problematic. Orthotopic cardiac transplantation can be successfully performed in patients who demonstrate reversibility of pulmonary vascular resistance. Nitric oxide appears to be the best agent to demonstrate reversibility of pulmonary resistance in these patients.

Outcomes for children with cardiomyopathy awaiting transplantation

OBJECTIVE

To determine factors associated with outcomes after listing for transplantation in children with cardiomyopathies.

BACKGROUND

Childhood cardiomyopathies form a heterogeneous group of diseases, and in many, the prognosis is poor, irrespective of the etiology. When profound heart failure develops, cardiac transplantation can be the only viable option for survival.

METHODS

We included all children with cardiomyopathy listed for transplantation between 12/89 and 4/98 in this historical cohort study.

RESULTS

We listed 31 patients, 15 male and 16 female, 27 with dilated and 4 with restrictive cardiomyopathy, for transplantation. The median age at listing was 5.7 years, with a range from fetal life to 17.8 years. Transplantation was achieved in 23 (74%), with a median interval from listing of 54 days, and a range from zero to 11.4 years. Of the patients, 14 were transplanted within 30 days of listing. Five patients (16%) died before transplantation. Within the Canadian algorithm, one of these was in the third state, and four in the fourth state. One patient was removed from the list after 12 days, having recovered from myocarditis, and two remain waiting transplantation after intervals of 121 and 476 days, respectively. Patients who died were more likely to be female (5/5 vs. 11/26; p=0.04) and to have been in the third or fourth states at listing (5/5 vs. 15/26; p=0.04). The use of mechanical ventricular assistance, in 10 patients, was not a predictor of an adverse outcome. While not statistically significant, survival to transplantation was associated with treatment using inhibitors of angiotensin converting enzyme, less mitral regurgitation, a higher mean ejection fraction and cardiac index, and lower right ventricular systolic pressure.

CONCLUSIONS

Children with cardiomyopathy awaiting transplantation have a mortality of 16% related to their clinical state at the time of listing.

Sudden death and cardiovascular collapse in children with restrictive cardiomyopathy

BACKGROUND

Restrictive cardiomyopathy (RCM) is rare in children, and the prognosis is poor. In the present study, we evaluated all pediatric patients with RCM who were at our institution during a 31-year period to determine the clinical outcome and cause of death. Those who sustained sudden, unanticipated cardiac arrests were evaluated for risk factors that are predictive of sudden death.

METHODS AND RESULTS

Eighteen consecutive patients were reviewed. Presentation, clinical course, laboratory data, and histopathological evidence of ischemia were compared between patients with and without sudden death events. The results demonstrated that patients who were at risk for sudden death were girls with chest pain, syncope, or both at presentation and without congestive heart failure. Although not statistically significant for sudden death, Holter monitor evidence of ischemia predicted death within months. Histopathological evidence of acute or chronic ischemia was found in the majority of patients, with acute ischemia more common among those who sustained sudden death events.

CONCLUSIONS

All children with RCM are at risk for ischemia-related complications and death, and some are at risk of sudden death. In the present study, patients at risk of sudden death appeared well and had no evidence of ongoing heart failure but often had signs or symptoms of ischemia characterized by chest pain, syncope, or both. ECGs and Holter monitors may be useful screening tools. The use of beta-blockade, the placement of an implantable cardioverter-defibrillator, and preferential status 1A or B listing for cardiac transplantation are proposed for pediatric patients with RCM and evidence of ongoing ischemia.

Clinical profile and outcome of idiopathic restrictive cardiomyopathy

BACKGROUND

Idiopathic restrictive cardiomyopathy is a poorly recognized entity of unknown cause characterized by nondilated, nonhypertrophied ventricles with diastolic dysfunction resulting in dilated atria and variable systolic function.

METHODS AND RESULTS

Between 1979 and 1996, 94 patients (61% women) 10 to 90 years old (mean, 64 years) met strict morphological echocardiographic criteria for idiopathic restrictive cardiomyopathy, mainly dilated atria with nonhypertrophied, nondilated ventricles. None had known infiltrative disease, hypertension of >5 years' duration, or cardiac or systemic conditions associated with restrictive filling. Nineteen percent were in NYHA class I, 53% in class II, and 28% in class III or IV. Atrial fibrillation was noted in 74% of patients and systolic dysfunction in 16%. Follow-up (mean, 68 months) was complete for 93 patients (99%). At follow-up, 47 patients (50%) had died, 32 (68%) of cardiovascular causes. Four had heart transplantation. The death rate compared with actuarial statistics was significantly higher than expected (P<0.0001). Kaplan-Meier 5-year survival was 64%, compared with expected survival of 85%. Multivariate analysis using proportional hazards showed that the risk of death approximately doubles with male sex (hazard ratio [HR] = 2.1), left atrial dimension >60 mm (HR = 2.3), age >70 years (HR = 2.0), and each increment of NYHA class (HR = 2.0).

CONCLUSIONS

Idiopathic restrictive cardiomyopathy or nondilated, nonhypertrophic ventricles with marked biatrial dilatation, as defined morphologically by echocardiography, affects predominantly elderly patients but can occur in any age group. Patients present with systemic and pulmonary venous congestion and atrial fibrillation and have a poor prognosis, particularly men >70 years old with higher NYHA class and left atrial dimension >60 mm.

Heart transplantation in children: indications. Report of the Ad Hoc Subcommittee of the Pediatric Committee of the American Society of Transplantation (AST)

This review details the indications for heart transplantation in children. Contraindications have evolved from absolute to relative. Controversial issues remain and this paper represents a consensus of more than a dozen centers that have programs that remain active performing pediatric heart transplants.

Multicore myopathy with restrictive cardiomyopathy

A 10-y-old girl is presented who suffered mild muscular weakness and exercise intolerance from the age of 1 y onwards, with progression appearing from the age of about 8 y. Multicore myopathy and restrictive cardiomyopathy were diagnosed. Literature concerning the coexistence of multicore myopathy and cardiomyopathy is reviewed.

Clinical approach to genetic cardiomyopathy in children

BACKGROUND

Cardiomyopathy (CM) remains one of the leading cardiac causes of death in children, although in the majority of cases, the cause is unknown. To have an impact on morbidity and mortality, attention must shift to etiology-specific treatments. The diagnostic evaluation of children with CM of genetic origin is complicated by the large number of rare genetic causes, the broad range of clinical presentations, and the array of specialized diagnostic tests and biochemical assays.

METHODS AND RESULTS

We present a multidisciplinary diagnostic approach to pediatric CM of genetic etiology. We specify criteria for abnormal left ventricular systolic performance and structure that suggest CM based on established normal echocardiographic measurements and list other indications to consider an evaluation for CM. We provide a differential diagnosis of genetic conditions associated with CM, classified as inborn errors of metabolism, malformation syndromes, neuromuscular diseases, and familial isolated CM disorders. A diagnostic strategy is offered that is based on the clinical presentation: biochemical abnormalities, encephalopathy, dysmorphic features or multiple malformations, neuromuscular disease, apparently isolated CM, and pathological specimen findings. Adjunctive treatment measures are recommended for severely ill patients in whom a metabolic cause of CM is suspected. A protocol is provided for the evaluation of moribund patients.

CONCLUSIONS

In summary, we hope to assist pediatric cardiologists and other subspecialists in the evaluation of children with CM for a possible genetic cause using a presentation-based approach. This should increase the percentage of children with CM for whom a diagnosis can be established, with important implications for treatment, prognosis, and genetic counseling.

Idiopathic restrictive cardiomyopathy in childhood: diagnostic features and clinical course

OBJECTIVE

To describe the clinical course and outcome of children with idiopathic restrictive cardiomyopathy (IRCM) and to present the Doppler echocardiographic features of this disease in childhood.

DESIGN

We reviewed the Mayo Clinic patient database for the period from 1975 to 1993 to identify children who underwent assessment for IRCM.

MATERIAL AND METHODS

Clinical records and diagnostic studies, including two-dimensional (2-D), M-mode, and Doppler echocardiograms, were reviewed for each patient. Characteristics were analyzed statistically to determine potential predictors of outcome.

RESULTS

Eight children (five girls and three boys) were diagnosed with IRCM between 1975 and 1993 at our institution. The median age at diagnosis was 11 years, and the median duration of follow-up was 11.5 years. Of the eight patients, five died (the median time from initial examination to death was 1 year). All five of these patients had clinical and radiographic evidence of pulmonary venous congestion. In all patients, 2-D and M-mode echocardiography revealed atrial enlargement without ventricular dilatation or hypertrophy. The four patients who underwent detailed diastolic Doppler assessment had findings consistent with restrictive filling and increased left ventricular end-diastolic pressure: (1) short mitral deceleration time, (2) increased pulmonary vein atrial reversal velocity and duration, and (3) pulmonary vein atrial reversal duration greater than mitral A-wave duration.

CONCLUSION

The prognosis for children with IRCM is poor. In this small group of patients, absence of pulmonary venous congestion most consistently predicted extended survival. A combined 2-D and Doppler echocardiographic examination provides a reliable noninvasive means of assessing the physiologic and morphologic features of IRCM in children.