Restrictive cardiomyopathy

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.

Compound heterozygous loss-of-function mutations in KIF20A are associated with a novel lethal congenital cardiomyopathy in two siblings

Congenital or neonatal cardiomyopathies are commonly associated with a poor prognosis and have multiple etiologies. In two siblings, a male and female, we identified an undescribed type of lethal congenital restrictive cardiomyopathy affecting the right ventricle. We hypothesized a novel autosomal recessive condition. To identify the cause, we performed genetic, in vitro and in vivo studies. Genome-wide SNP typing and parametric linkage analysis was done in a recessive model to identify candidate regions. Exome sequencing analysis was done in unaffected and affected siblings. In the linkage regions, we selected candidate genes that harbor two rare variants with predicted functional effects in the patients and for which the unaffected sibling is either heterozygous or homozygous reference. We identified two compound heterozygous variants in KIF20A; a maternal missense variant (c.544C>T: p.R182W) and a paternal frameshift mutation (c.1905delT: p.S635Tfs*15). Functional studies confirmed that the R182W mutation creates an ATPase defective form of KIF20A which is not able to support efficient transport of Aurora B as part of the chromosomal passenger complex. Due to this, Aurora B remains trapped on chromatin in dividing cells and fails to translocate to the spindle midzone during cytokinesis. Translational blocking of KIF20A in a zebrafish model resulted in a cardiomyopathy phenotype. We identified a novel autosomal recessive congenital restrictive cardiomyopathy, caused by a near complete loss-of-function of KIF20A. This finding further illustrates the relationship of cytokinesis and congenital cardiomyopathy.

Peculiar Clinical Presentation of Coxsackievirus B4 Infection: Neonatal Restrictive Cardiomyopathy

Introduction  Restrictive cardiomyopathy in fetuses and neonates is extremely rare and has a poor outcome. Its etiology in neonates is elusive: metabolic diseases (e.g., Gaucher, Hurler syndrome), neuromuscular disorders (e.g., muscular dystrophies, myofibrillar myopathies), or rare presentation of genetic syndromes (e.g., Coffin-Lowry syndrome) account for a minority of the cases, the majority remaining idiopathic. Case Study  We report the case of a 17-day-old male infant presenting cardiogenic shock following a restrictive dysfunction of the left ventricle. Postmortem investigations revealed coxsackievirus B4 myocarditis with histological lesions limited to the left heart. However, polymerase chain reaction (PCR) for coxsackievirus B4 was positive in the left as well as in the right ventricular samples. Conclusion  In conclusion, coxsackievirus myocarditis is a cause of restrictive cardiomyopathy, and its diagnosis should involve PCR screening as a more sensitive technique.

Nomenclature and systems of classification for cardiomyopathy in children

There has been a progressive evolution in systems of classification for cardiomyopathy, driven by advances in imaging modalities, disease recognition, and genetics, following initial clinical descriptions in the 1960s. A pathophysiological classification emerged and was endorsed by World Health Organisation Task Forces in 1980 and 1995: dilated, hypertrophic, restrictive, and arrhythmogenic right ventricular cardiomyopathies; subdivided into idiopathic and disease-specific cardiomyopathies. Genetic advances have increasingly linked "idiopathic" phenotypes to specific mutations, although most linkages exhibit highly variable or little genotype-phenotype correlation, confounded by age-dependent changes and varying penetrance. The following two dominant classification systems are currently in use, with advocates in both continents. First, American Heart Association (2006): "A heterogeneous group of diseases of the myocardium associated with mechanical and/or electrical dysfunction that usually exhibit inappropriate ventricular hypertrophy or dilatation due to a variety of causes that frequently are genetic". These are subdivided to those predominantly involving the heart - primary - due to genetic mutation, including ion channelopathies, acquired disease, or mixed; and those with systemic involvement in other organ systems - secondary. Second, European Society of Cardiology (2008): "A myocardial disorder in which heart muscle is structurally and functionally abnormal… sufficient to cause the observed myocardial abnormality", with subdivision to familial and non-familial, excluding ion channelopathies, and split to specific disease subtypes and idiopathic. Further differences exist in the definitions for hypertrophic cardiomyopathy; however, whichever high-level classification is used, the clinical reality remains phenotype driven. Clinical evaluation and diagnostic imaging dominate initial patient contact, revealing diagnostic red flags that determine further specific tests. Genetic testing is undertaken early. A recent attempt to harmonise these competing systems named the MOGE(S) system, based on descriptive logical nosology, currently remains unproven as a fully practical solution.

Sudden death possibly related to lenalidomide given for cardiac and muscle AL amyloidosis secondary to light chain deposition disease

OBJECTIVES

Restrictive cardiomyopathy due to AL amyloidosis has not been reported as the cause of sudden death. The risk of sudden death in AL amyloidosis may be further increased by potentially cardiotoxic medication, as in the following case.

CASE REPORT

In a 69-year-old female, AL amyloidosis from light-chain deposition disease manifested as gastrointestinal pseudo-obstruction, restrictive cardiomyopathy, and secondary myopathy. AL amyloidosis was histologically confirmed by endomyocardial biopsy and muscle biopsy. One month after initiation of steroids and lenalidomide the patient suddenly died during sleep. It is speculated that sudden death was due to restrictive cardiomyopathy, cardiotoxicity of lenalidomide, pulmonary embolism, sudden unexplained death in epilepsy syndrome or stroke. The possible causes of sudden death are discussed.

CONCLUSIONS

This case shows that AL amyloidosis from light-chain deposition disease may predominantly affect the intestines, myocardium and the skeletal muscle and that lenalidomide may have a beneficial effect on the amyloidosis but should be given with caution for its potential arrhythmogenic and thrombogenic side-effects.

Therapeutic potential of c-Myc inhibition in the treatment of hypertrophic cardiomyopathy

Investigating the pathophysiological importance of the molecular and mechanical development of cardiomyopathy is critical to find new and broader means of protection against this disease that is increasing in prevalence and impact. The current available treatment options for cardiomyopathy mainly focus on treating symptoms and strive to make the patient more comfortable while preventing progression of disease and sudden death. The proto-oncogene c-Myc (Myc) has been shown to be increased in many different types of heart disease, including hypertrophic cardiomyopathy, before any signs of the disease are present. As the mechanisms of action and multiple pathways of dependent actions of Myc are being dissected by many research groups, inhibition of Myc is becoming an attractive paradigm for prevention and treatment of cardiomyopathy and heart failure. Elucidating the role Myc plays in the development, propagation and perpetuation of cardiomyopathy and heart failure will one day translate into potential therapeutics for cardiomyopathy.

[Arrhytmogenic right ventricle--prognostic significance of exercise test]

The authors summarize the present knowledge on arrhythmogenic right ventricular cardiomyopathy/dysplasia. Limited data are available about natural history of asymptomatic patients with arrhythmogenic right ventricle cardiomyopathy/dysplasia, who have a ventricular tachycardia during exercise test. A 25-year old female patient was treated with osteosynthesis because of ankle injury. Cardiology consultation was performed because of an abnormal ECG. Physical examination was normal. ECG showed a normal sinus rhythm, left axis deviation, negative T waves in leads II, III, aVF and V2-V6. Chest X-ray and laboratory findings were normal. Echocardiography showed normal left ventricular ejection fraction along with inferior akinesis and dilated right ventricle. Bicycle exercise test revealed a good exercise tolerability (9 MET), and after sporadic ventricular extra systoles ventricular tachycardia developed lasting for 3 minutes, which spontaneously stopped after aborting the test and performed abdominal strain. MRI was performed which has shown normal left ventricular size, wall motion and ejection fraction and depressed right ventricle function (ejection fraction 31.6%) enlarged right ventricular end-systolic and diastolic volumes, hypo-akinetic regions without aneurysm and bulging. No contrast enhancement was seen in the thin right ventricular wall. According to abnormal ECG and MRI findings arrhythmogenic right ventricle cardiomyopathy/dysplasia was diagnosed. No ICD implantation was indicated because the patient was asymptomatic, and no sudden cardiac death occurred in the family. Three month later the patient was found dead. At autopsy the right ventricular chamber was markedly enlarged, with multiple translucent areas of fatty accumulation accompanied with extended myocytes loss. There was a characteristic triangle dysplasia: the inflow, outflow tracts and apical areas. The coronaries were free of atherosclerosis. Mallory's phosphotungstic acid-hematoxilin stain demonstrated the presence of fibrosis within the scattered myocardium.

CONCLUSION

malignant ventricular arrhythmia provoked by exercise test in an asymptomatic arrhythmogenic right ventricle cardiomyopathy/dysplasia patient with negative family history should be an indication for ICD implantation.