Familial restrictive cardiomyopathy with atrioventricular block and skeletal myopathy

Prevalence and Impact of Arrhythmia on Outcomes in Restrictive Cardiomyopathy-A Report from the Beijing Municipal Health Commission Information Center (BMHCIC) Database

BACKGROUND

Data on the outcomes of restrictive cardiomyopathy (RCM) are limited, when the condition is complicated with arrhythmia. This study was designed to investigate the prevalence of atrial fibrillation (AF), ventricular tachycardia (VT) and bradycardia (BC) and their impact on adverse outcomes (intra-cardiac thrombus, stroke and systematic embolism [SSE], heart failure and death) of RCM.

METHODS AND RESULTS

The retrospective cohort study used data collected from the Beijing Municipal Health Commission Information Center (BMHCIC) database from 1 January 2010 to 31 December 2020. There were 745 (64.9%) patients with AF, 117 (10.2%) patients with VT and 311 (27.1%) patients with bradycardia. The presence of AF was associated with an increased risk of SSE (adjusted HR:1.37, 95%CI:1.02-1.83, p = 0.04) and heart failure (aHR:1.36, 95%CI:1.17-1.58, p < 0.001). VT was associated with an increased risk of intracardiac thrombus (aHR:2.34, 95%CI:1.36-4.01, p = 0.002) and death (aHR:2.07, 95%CI:1.19-3.59, p = 0.01). Bradycardia did not increase the adverse outcomes in RCM. The results remained consistent and steady when AF, VT and bradycardia were adjusted as competing factors.

CONCLUSIONS

Cardiac arrhythmia are highly prevalent and associated with adverse outcomes in patients with RCM. AF and VT are more likely to be associated with intracardiac thrombosis, and the presence of AF increased the risk of SSE and HF. The presence of VT increased the risk of death.

Epidemiology of the inherited cardiomyopathies

In the absence of contemporary, population-based epidemiological studies, estimates of the incidence and prevalence of the inherited cardiomyopathies have been derived from screening studies, most often of young adult populations, to assess cardiovascular risk or to detect the presence of disease in athletes or military recruits. The global estimates for hypertrophic cardiomyopathy (1/500 individuals), dilated cardiomyopathy (1/250) and arrhythmogenic right ventricular cardiomyopathy (1/5,000) are probably conservative given that only individuals who fulfil diagnostic criteria would have been included. This caveat is highly relevant because a substantial minority or even a majority of individuals who carry disease-causing genetic variants and are at risk of disease complications have incomplete and/or late-onset disease expression. The genetic literature on cardiomyopathy, which is often focused on the identification of genetic variants, has been biased in favour of pedigrees with higher penetrance. In clinical practice, an abnormal electrocardiogram with normal or non-diagnostic imaging results is a common finding for the sarcomere variants that cause hypertrophic cardiomyopathy, the titin and sarcomere variants that cause dilated cardiomyopathy and the desmosomal variants that cause either arrhythmogenic right ventricular cardiomyopathy or dilated cardiomyopathy. Therefore, defining the genetic epidemiology is also challenging given the overlapping phenotypes, incomplete and age-related expression, and highly variable penetrance even within individual families carrying the same genetic variant.

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.

Precision medicine approach to genetic cardiomyopathy

Precision medicine aims to achieve improved survival by strategies that recognize the genetic and phenotypic individuality of patients and stratify treatment accordingly. Genetic cardiomyopathies represent an ideal disease group to fully embark on this concept: they are in total frequent diseases with a marked morbidity and mortality and there is ample knowledge about their predisposing genetic factors and associated functional mechanisms. The current review highlights the genetic etiology and gives examples of the diverse treatment strategies that are envisaged in the future.

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.

Sex differences in cardiomyopathies

Cardiomyopathies are a heterogeneous group of heart muscle diseases with a variety of specific phenotypes. According to the contemporary European Society of Cardiology classification, they are classified into hypertrophic (HCM), dilated (DCM), arrhythmogenic right ventricular (ARVC), restrictive (RCM), and unclassified cardiomyopathies. Each class is aetiologically further categorized into inherited (familial) and non-inherited (non-familial) forms. There is substantial evidence that biological sex is a strong modulator of the clinical manifestation of these cardiomyopathies, and sex-specific characteristics are detectable in all classes. For the clinician, it is important to know the sex-specific aspects of clinical disease expression and the potential modes of inheritance or the hereditary influences underlying the development of cardiomyopathies, since these may aid in diagnosing such diseases in both sexes.

Titin mutation in familial restrictive cardiomyopathy

BACKGROUND

Familial restrictive cardiomyopathy (RCM) caused by a single gene mutation is the least common of the inherited cardiomyopathies. Only a few RCM-causing mutations have been described. Most mutations causing RCM are located in sarcomere protein genes which also cause hypertrophic cardiomyopathy (HCM). Other genes associated with RCM include the desmin and familial amyloidosis genes. In the present study we describe familial RCM with severe heart failure triggered by a de novo mutation in TTN, encoding the huge muscle filament protein titin.

METHODS AND RESULTS

Family members underwent physical examination, ECG and Doppler echocardiogram studies. The family comprised 6 affected individuals aged 12-35 years. Linkage to candidate loci was performed, followed by gene sequencing. Candidate loci/gene analysis excluded 18 candidate genes but showed segregation with a common haplotype surrounding the TTN locus. Sequence analysis identified a de novo mutation within exon 266 of the TTN gene, resulting in the replacement of tyrosine by cysteine. p.Y7621C affects a highly conserved region in the protein within a fibronectin-3 domain, belonging to the A/I junction region of titin. No other disease-causing mutation was identified in cardiomyopathy genes by whole exome sequencing.

CONCLUSIONS

Our study shows, for the first time, that mutations in TTN can cause restrictive cardiomyopathy. The giant filament titin is considered to be a determinant of a resting tension of the sarcomere and this report provides genetic evidence of its crucial role in diastolic function.

Genetic testing in the contemporary diagnosis of cardiomyopathy

The heritable cardiomyopathies are relatively common conditions that can lead to heart failure and sudden cardiac death. Family history collection, genetic testing and genetic counseling are recommended for these patients and families in multiple practice guidelines and consensus statements. Research discoveries and rapidly dropping costs of DNA sequencing technologies have resulted in the availability of multiple cardiomyopathy genetic testing panels. Genetic testing not only helps in determining the underlying etiology of idiopathic and familial cardiomyopathies, but is also a powerful tool in the determination of which relatives are at-risk and which are not. Both pre- and post-test genetic counseling is an imperative component of genetic testing, as there are many benefits and limitations of genetic testing that need discussed with each patient undergoing this process.

Cardiomyopathy in neurological disorders

According to the American Heart Association, cardiomyopathies are classified as primary (solely or predominantly confined to heart muscle), secondary (those showing pathological myocardial involvement as part of a neuromuscular disorder) and those in which cardiomyopathy is the first/predominant manifestation of a neuromuscular disorder. Cardiomyopathies may be further classified as hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, or unclassified cardiomyopathy (noncompaction, Takotsubo-cardiomyopathy). This review focuses on secondary cardiomyopathies and those in which cardiomyopathy is the predominant manifestation of a myopathy. Any of them may cause neurological disease, and any of them may be a manifestation of a neurological disorder. Neurological disease most frequently caused by cardiomyopathies is ischemic stroke, followed by transitory ischemic attack, syncope, or vertigo. Neurological disease, which most frequently manifests with cardiomyopathies are the neuromuscular disorders. Most commonly associated with cardiomyopathies are muscular dystrophies, myofibrillar myopathies, congenital myopathies and metabolic myopathies. Management of neurological disease caused by cardiomyopathies is not at variance from the same neurological disorders due to other causes. Management of secondary cardiomyopathies is not different from that of cardiomyopathies due to other causes either. Patients with neuromuscular disorders require early cardiologic investigations and close follow-ups, patients with cardiomyopathies require neurological investigation and avoidance of muscle toxic medication if a neuromuscular disorder is diagnosed. Which patients with cardiomyopathy profit most from primary stroke prevention is unsolved and requires further investigations.

Cardiomyopathy classification: ongoing debate in the genomics era

Cardiomyopathies represent a group of diseases of the myocardium of the heart and include diseases both primarily of the cardiac muscle and systemic diseases leading to adverse effects on the heart muscle size, shape, and function. Traditionally cardiomyopathies were defined according to phenotypical appearance. Now, as our understanding of the pathophysiology of the different entities classified under each of the different phenotypes improves and our knowledge of the molecular and genetic basis for these entities progresses, the traditional classifications seem oversimplistic and do not reflect current understanding of this myriad of diseases and disease processes. Although our knowledge of the exact basis of many of the disease processes of cardiomyopathies is still in its infancy, it is important to have a classification system that has the ability to incorporate the coming tide of molecular and genetic information. This paper discusses how the traditional classification of cardiomyopathies based on morphology has evolved due to rapid advances in our understanding of the genetic and molecular basis for many of these clinical entities.

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.

Clinical screening and genetic testing

Clinical screening is most effective in diseases in which the disease is in its earliest form and may not have symptoms or signs but can be readily diagnosed with an inexpensive, noninvasive test. This article discusses the general principles of genetic disease architecture that can guide screening and diagnostic approaches for all of the cardiomyopathies and inherited diseases. It addresses how the genetic architecture of the trait guides, and how clinical characteristics of the disease influence, a clinical screening approach.

Genetics of restrictive cardiomyopathy

Restrictive physiology, a severe form of diastolic dysfunction, is characteristically observed in the setting of constrictive pericarditis and myocardial restriction. The latter is commonly due to systemic diseases, some of which are inherited as mendelian traits (eg, hereditary amyloidosis), while others are multifactorial (eg, sarcoidosis). When restrictive physiology occurs as an early and dominant feature of a primary myocardial disorder, it may be termed restrictive cardiomyopathy. In the past decade, clinical and genetic studies have demonstrated that restrictive cardiomyopathy as such is part of the spectrum of sarcomeric disease and frequently coexists with hypertrophic cardiomyopathy in affected families.

Clinical screening and genetic testing

Clinical screening is most effective in diseases in which the disease in its earliest form and may not have symptoms or signs but can be readily diagnosed with an inexpensive, noninvasive test. This article discusses the general principles of genetic disease architecture that can guide screening and diagnostic approaches for all of the cardiomyopathies and inherited diseases. It addresses how the genetic architecture of the trait guides, and how clinical characteristics of the disease influence, a clinical screening approach.

Extracardiac medical and neuromuscular implications in restrictive cardiomyopathy

Restrictive cardiomyopathy (RCMP) is characterized by restrictive filling and reduced diastolic volume of either or both ventricles with normal or near-normal systolic function and wall thickness. It may occur idiopathically or as a cardiac manifestation of systemic diseases such as scleroderma, amyloidosis, Churg-Strauss syndrome, cystinosis, sarcoidosis, lymphoma, Gaucher's disease, hemochromatosis, Fabry's disease, pseudoxanthoma elasticum, hypereosinophilic syndrome, carcinoid, Noonan's syndrome, reactive arthritis, or Werner's syndrome and various neuromuscular disorders. Whereas in idiopathic RCMP the therapeutic options are only treatment of cardiac congestion, in cases with an underlying disorder, a causal therapy may be available. Patients with RCMP should be investigated as soon as the cardiac diagnosis is established for extracardiac diseases to detect a possibly treatable cause of RCMP before the disease becomes intractable. These investigations include a diligent clinical history and examination, blood tests, and ophthalmologic, otologic, dermatologic, gastroenterologic, nephrologic, hematologic, and neurologic examinations. If extracardiac examinations do not reveal a plausible cause for RCMP, endomyocardial biopsy is indicated.

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.

Familial restrictive cardiomyopathy with atrioventricular block without skeletal myopathy

Familial restrictive cardiomyopathy is an autosomal dominant cardiomyopathy histologically characterized by myocyte hypertrophy and interstitial fibrosis. The case of a 54-year-old man diagnosed with restrictive cardiomyopathy is reported. The patient had been implanted with a two-chambered pacemaker for a complete atrioventricular block 12 years before. The family history was positive with several affected members, none of whom had findings of skeletal myopathy. Genetic analysis of the index patient revealed no troponin I mutations.

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.

Idiopathic restrictive cardiomyopathy is part of the clinical expression of cardiac troponin I mutations

Restrictive cardiomyopathy (RCM) is an uncommon heart muscle disorder characterized by impaired filling of the ventricles with reduced volume in the presence of normal or near normal wall thickness and systolic function. The disease may be associated with systemic disease but is most often idiopathic. We recognized a large family in which individuals were affected by either idiopathic RCM or hypertrophic cardiomyopathy (HCM). Linkage analysis to selected sarcomeric contractile protein genes identified cardiac troponin I (TNNI3) as the likely disease gene. Subsequent mutation analysis revealed a novel missense mutation, which cosegregated with the disease in the family (lod score: 4.8). To determine if idiopathic RCM is part of the clinical expression of TNNI3 mutations, genetic investigations of the gene were performed in an additional nine unrelated RCM patients with restrictive filling patterns, bi-atrial dilatation, normal systolic function, and normal wall thickness. TNNI3 mutations were identified in six of these nine RCM patients. Two of the mutations identified in young individuals were de novo mutations. All mutations appeared in conserved and functionally important domains of the gene. This article was published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org.

Clinical and molecular studies of a large family with desmin-associated restrictive cardiomyopathy

Patients with restrictive cardiomyopathy (RC) have impaired diastolic function, but intact systolic function until later stages of the disease, ultimately leading to heart failure. Primary RC is often sporadic, but also may be inherited in an autosomal dominant fashion, particularly the idiopathic forms. Recently there has been great interest in inherited cardiomyopathy associated with myocyte desmin deposition ('desminopathies'). In some such families, desmin or alpha-B crystallin gene mutation is the underlying cause, and the desmin accumulation affects skeletal muscle as well, usually causing skeletal myopathy. We describe a large family with apparent autosomal dominant inheritance of desmin-associated RC spanning four generations, with the age of onset and severity/rate of progression being highly variable. This family is relatively unique in that there is no symptom-based evidence of skeletal muscle involvement, and the known desminopathy and cardiomyopathy genes/loci have been ruled out. These data support literature suggesting that desmin deposition may be associated with different underlying gene defects, and that a novel desminopathy gene is responsible for the condition in this family.

Cardiomyopathy in childhood, mitochondrial dysfunction, and the role of L-carnitine

Cardiomyopathy in childhood is associated with high morbidity and mortality rates. Many metabolic causes have been identified, including genetic or acquired defects in mitochondrial energy production affecting beta-oxidation, carnitine transport, and the electron transport chain. Combining conventional inotropic and antiarrhythmic therapy with metabolic interventions has improved overall outcome. L-carnitine, a natural substance involved in mitochondrial transport of fatty acids, is one such therapy and plays a central role in the regulation of the inner mitochondrial supply of free coenzyme A. Carnitine deficiency can be caused by both genetic and environmental causes with resultant signs and symptoms of metabolic disease, including cardiomyopathy. Administration of L-carnitine can result in improvement or resolution of the cardiomyopathy.

A distinctive autosomal dominant vacuolar neuromyopathy linked to 19p13

OBJECTIVE

To characterize a kindred with a distinctive autosomal dominant neuromuscular disorder.

BACKGROUND

The authors studied a large Italian family affected by a progressive neuromyopathy. Ten individuals over three generations were affected. The disease was characterized by onset from the late teens to early 50s with distal leg weakness and atrophy, development of generalized muscle weakness with distal-to-proximal progression sparing facial and ocular muscles, dysphonia and dysphagia, pes cavus and areflexia, variable clinical expression ranging from subclinical myopathy to severely disabling weakness, and mixed neurogenic and myopathic abnormalities on electromyography.

METHODS

Morphologic, immunocytochemical, and ultrastructural studies were performed in muscle biopsies from three affected patients. A genomewide linkage analysis through the genotyping of 292 microsatellite markers spanning the 22 autosomes was undertaken to map the disorder segregating in this family.

RESULTS

All muscle biopsies showed variation of fiber size, panesterase-positive angular fibers, mild to severe fibrosis, and numerous "rimmed vacuoles." Electron microscopy failed to demonstrate the nuclear or cytoplasmic filamentous inclusions specific of inclusion-body myopathies and, accordingly, immunohistochemistry did not show any positivity with SMI-31 antibodies detecting hyperphosphorylated tau. Preliminary analysis of 292 microsatellite markers provided evidence for linkage to chromosome 19p13.

CONCLUSIONS

This distinctive autosomal dominant disorder is characterized by a vacuolar neuromyopathy. Localization to chromosome 19p13 will allow the genetic relationship between this disease and inherited myopathies with rimmed vacuoles, in particular autosomal dominant inclusion-body myopathies, to be defined.

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.

Morphologic spectrum of primary restrictive cardiomyopathy

A restrictive hemodynamic profile with left ventricular (LV) end-diastolic volume < 100 ml/m2 and LV end-diastolic pressure > 18 mm Hg, in the absence of endomyocardial, pericardial, and specific cardiomyopathy, is a peculiar feature of primary restrictive cardiomyopathy. From 1985 to 1994, 7 hearts of patients who met the above hemodynamic criteria and underwent endomyocardial biopsy because of heart failure, were studied through gross (5 cardiectomies and 2 autopsies), histologic, and electron microscopic investigations. Ages ranged from 9 to 48 years (mean age 29 +/- 13). Four patients (57%) had a positive family history: 2 for hypertrophic and 2 for restrictive cardiomyopathy. Three patterns were identified in the 7 hearts: (1) pure restrictive form in 4 cases with mass/volume ratio 1.2 +/- 0.5 g/ml, ejection fraction 58 +/- 5%, LV end-diastolic volume 67.5 +/- 12.6 ml/m2, LV end-diastolic pressure 26.7 +/- 3.5 mm Hg; (2) hypertrophic-restrictive form in 2 cases with mass/volume ratio 1.5 +/- 0.07 g/ml, ejection fraction 62 +/- 1%, LV end-diastolic volume 69 +/- 10 ml/m2, LV end-diastolic pressure 30 +/- 7 mm Hg; and (3) mildly dilated restrictive form in 1 case with mass/volume ratio 0.9 g/ml, ejection fraction 25%, LV end-diastolic volume 98 ml/m2, LV end-diastolic pressure 40 mm Hg. Histology and electron microscopy disclosed myocardial and myofibrillar disarray and endoperimysial interstitial fibrosis in each pattern. The familial forms suggest the presence of a genetic abnormality. Primary restrictive cardiomyopathy may present with or without hypertrophy and shares similar microscopic pictures with hypertrophic cardiomyopathy. The 2 entities may represent a different phenotypic expression of the same genetic disease.

Restrictive cardiomyopathies in childhood. Etiologies and natural history

Restrictive cardiomyopathy is rare in childhood and little is known about the causes and outcome. This lack of information results in extrapolation of adult data to the care and management of children, who might require different treatment from that of adults. This study was undertaken retrospectively to evaluate the causes and natural history of restrictive cardiomyopathy in childhood. Twelve cases of restrictive cardiomyopathy were identified by database review of patient records from 1967 to 1994. The cases were selected on the basis of echocardiographic and cardiac catheterization criteria. Charts were reviewed for the following variables: age, sex, cause, right-and left-sided hemodynamics, pulmonary vascular resistance index, shortening fraction, therapy, and outcome. There were 6 males and 6 females with a mean age of 4.6 years at presentation (median, 3.4 yr; range, 0.9 to 12.3 yr). Etiologies included hypertrophic cardiomyopathy in 3 patients, cardiac hypertrophy with restrictive physiology in 3, idiopathic in 2, familial in 2 (twins), "chronic eosinophilia" in 1, and "post inflammatory" with no definitive causes in 1. At presentation the mean shortening fraction was 33% +/- 2% (mean +/- SEM), average right ventricular pressures were 44/13 +/- 3/1, average left ventricular pressures were 88/25 +/- 4/3, and the mean pulmonary vascular resistance index was 3.4 +/- 1.3 U.m2 (n = 9), but increased to 9.9 +/- 3.1 U.m2 (n = 5, p = 0.04) by 1 to 4 years after diagnosis. Four of the 12 patients had embolic events (1, recurrent pulmonary emboli; 1, saddle femoral embolus; 2, cerebrovascular accidents) and 9 of 12 died within 6.3 years despite medical therapies, which included diuretics, verapamil, propranolol, digoxin, and captopril. In conclusion, restrictive cardiomyopathy in childhood is commonly idiopathic or associated with cardiac hypertrophy, and the prognosis is poor. Embolic events occurred in 33% of our patients, and 9 of 12 patients died within 6.3 years. Within 1 to 4 years of diagnosis, patients may develop a markedly elevated pulmonary vascular resistance index; therefore, transplantation should be considered early.

Familial cardiomyopathy underlies syndrome of right bundle branch block, ST segment elevation and sudden death

OBJECTIVES

We sought to assess whether structural heart disease underlies the syndrome of right bundle branch block, persistent ST segment elevation and sudden death.

BACKGROUND

Ventricular fibrillation and sudden death may occur in patients with a distinctive electrocardiographic (ECG) pattern of right bundle branch block and persistent ST segment elevation in the right precordial leads.

METHODS

Sixteen members of a family affected by this syndrome underwent noninvasive cardiac evaluation, including electrocardiography, Holter ambulatory ECG monitoring, stress testing, echocardiography and signal-averaged electrocardiography; two patients had electrophysiologic and angiographic study. Endomyocardial biopsy was performed in one living patient, and postmortem examination, including study of the specialized conduction system, was performed in one victim of sudden death.

RESULTS

Five years before a fatal cardiac arrest, the proband had been resuscitated from sudden cardiac arrest due to recorded ventricular fibrillation. Serial ECGs showed a prolonged PR interval, right bundle branch block, left-axis deviation and persistent ST segment elevation in the right precordial leads, in the absence of clinical heart disease. Postmortem investigation disclosed right ventricular dilation and myocardial atrophy with adipose replacement of the right ventricular free wall as well as sclerotic interruption of the right bundle branch. A variable degree of right bundle branch block and upsloping right precordial ST segment was observed in seven family members; four of the seven had structural right ventricular abnormalities on echocardiography and late potentials on signal-averaged electrocardiography. A sib of the proband also had a prolonged HV interval, inducible ventricular tachycardia and fibrofatty replacement on endomyocardial biopsy.

CONCLUSIONS

An autosomal dominant familial cardiomyopathy, mainly involving the right ventricle and the conduction system, accounted for the ECG changes and the electrical instability of the syndrome.

Restrictive and hypertrophic cardiomyopathies in Noonan syndrome: the overlap syndromes

A woman with Noonan syndrome had clinical and haemodynamic features of restrictive cardiomyopathy. There was no ventricular hypertrophy on echocardiography but myocardial biopsies showed myocyte hypertrophy without pathological disarray. This case illustrates the overlap of the cardiac phenotypes of Noonan syndrome, restrictive cardiomyopathy, and hypertrophic cardiomyopathy.

Probable right ventricular dysplasia and patent foramen ovale presenting with cyanosis and clubbing in a patient with characteristics of Noonan syndrome

Probable right ventricular dysplasia and a patent foramen ovale resulted in cyanotic heart disease in a patient with some characteristics of Noonan syndrome.

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.

Noonan's cardiomyopathy: a non-hypertrophic variant

OBJECTIVE

To describe the association of the Noonan's phenotype and a primary, familial non-hypertrophic cardiomyopathy with restrictive pathophysiology.

DESIGN

Observational study.

SETTING

Tertiary cardiac referral centre.

PATIENTS

Affected family members.

METHODS

Two generations of a single family were examined and a description of the clinical characteristics and electrocardiographic, echocardiographic, and haemodynamic data of those affected is given.

RESULTS

Three family members have classic Noonan's phenotype and all have a non-dilated, non-hypertrophic cardiomyopathy. Inheritance is autosomal dominant but with variable penetrance. The electrocardiograms show increased left ventricular voltages in two patients. On echocardiography left ventricular wall and internal end diastolic dimensions are normal, and there is considerable bilateral atrial enlargement. Systolic function is moderately impaired in one patient and mildly impaired in another. Doppler echocardiography showed restrictive pathophysiology as an early end of left ventricular filling and considerable reversal of flow in the superior vena cava during atrial systole.

CONCLUSION

Hypertrophic cardiomyopathy is well described in Noonan's syndrome. This is the first report of a non-hypertrophic cardiomyopathy with echocardiographic and haemodynamic features of restrictive pathophysiology.

Assignment of patients into the classification of cardiomyopathies

The original classifications of the cardiomyopathies based on anatomic criteria from radiographic and necropsy studies, as well as hemodynamic criteria from clinical and catheterization data, have been supplemented in recent years by information from noninvasive techniques. Echocardiography, radionuclide methods, and ambulatory ECG, in particular, have facilitated the ethical screening of family members and those less symptomatic than patients on whom the original classification was based. These powerful methods show a broad spectrum of anatomy and ventricular physiology along the natural history of and within the traditional categories of the cardiomyopathies. They also provide data on the effect of ventricular loading conditions affecting a range of diastolic filling patterns. This review has attempted to point out the areas of overlap among and/or controversy about the categories that have led us to a feeling of frustration when trying to neatly classify individual patients. The addition of filling patterns from Doppler echocardiography and nuclear angiography to the standard methods has been reviewed and hopefully will lend more perspective to the range of physiology seen in these conditions. The categories of cardiomyopathy should not be seen as excluding patients with the newly recognized variations in anatomy and ventricular filling patterns. Rather, the classification provides a framework on which to build and expand our understanding of these important conditions.

Clinical profile and outcome of restrictive cardiomyopathy in children

The clinical profile and outcome of idiopathic restrictive cardiomyopathy in a group of eight children are reviewed. There were six girls and two boys. Age at presentation was 4.0 +/- 2.6 years (range 1.3 to 9.5 years). All patients had evidence of congestive heart failure with systemic venous congestion. Right or left atrial enlargement was the most consistent ECG finding and was present in all patients. Left ventricular shortening fraction was normal in five patients, increased in two, and mildly reduced in one. The most striking echocardiographic feature was severe biatrial dilatation in the presence of normal or near-normal ventricular cavity dimensions. Marked elevation of left ventricular end-diastolic pressure was noted in all seven patients undergoing cardiac catheterization (34 +/- 7 torr; range 24 to 40 torr). Right ventricular end-diastolic pressure was elevated but significantly different from left ventricular pressure (18 +/- 7 torr; p less than 0.01). A characteristic early diastolic dip with a rapid rise to an elevated plateau (square root sign) was present in five of seven patients. Median survival was 1.4 years. Six patients died 0.2 to 7.0 years after they were initially seen. The actuarial survival rate 1.5 years after presentation was 44%, decreasing to 29% at 4 years. Restrictive cardiomyopathy has a worse prognosis in children than in adults. In part this may reflect the more advanced symptoms of congestive failure at initial presentation. Pediatric patients should be considered for early cardiac transplantation.

Primary restrictive cardiomyopathy: clinical and pathologic characteristics

Twenty-four patients with restrictive cardiomyopathy were identified at St. Thomas' Hospital during a 17-year period. All had endomyocardial biopsy, but in two patients the biopsy specimens were small and nondiagnostic. Seven patients had amyloidosis and five had other specific heart muscle diseases. The remaining 10 patients with primary restrictive cardiomyopathy had myocyte hypertrophy or interstitial fibrosis, or both. Patients with primary restrictive cardiomyopathy presented earlier but survived longer after presentation than did those with amyloidosis. In each group, survival after cardiac catheterization was related to cardiac index but not to filling pressures. Primary restrictive cardiomyopathy was associated with complete heart block in four patients, two of whom had skeletal myopathy. One had a family history of dominantly inherited skeletal myopathy. Primary restrictive cardiomyopathy was present in a mother and daughter. Two other patients had a family history of heart failure, sudden death or complete heart block, alone or in combination, at a young age. Restrictive hemodynamics and complete heart block were present in patients even in the absence of significant fibrosis. The data suggest that primary restrictive cardiomyopathy may be a distinct myopathy with dominant inheritance and incomplete penetrance that is expressed morphologically as myocyte hypertrophy and interstitial fibrosis. Skeletal myopathy may be associated with the cardiomyopathy.

Cardiomyopathy: a necessary revision of the WHO classification

The classification of myocardial disease proposed by the WHO/ISFC task force in 1980 distinguishes specific heart muscle diseases from myocardial diseases of unknown origin, termed cardiomyopathies, and differentiated into the dilated, hypertrophic and restrictive forms. This last group includes endomyocardiofibrosis and fibroblastic parietal endocarditis. In more recent years, two new forms of heart muscle disease have been recognized: so-called "primary" restrictive cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Primary restrictive cardiomyopathy is characterized anatomically by normally sized, non-hypertrophic ventricles with dilated atria, and functionally by impaired diastolic compliance due to myocardial stiffness. The clinical picture is that of chronic congestive heart failure; histology shows interstitial fibrosis and myocardial disarray, but not hypereosinophilia. In arrhythmogenic right ventricular cardiomyopathy, the myocardium of the right ventricular free wall is substituted by fibrous and/or adipose tissue, which results in regional dynamic alterations and ominous ventricular arrhythmias. The left ventricle is usually spared. Both forms should be classified as heart muscle diseases of unknown origin, and kept clearly distinct from the other cardiomyopathies listed in the WHO classification.