Heart & vascular pathology


Primary and secondary dilated cardiomyopathy

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Last staff update: 31 December 2020

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PubMed Search: Dilated cardiomyopathy [title] primary secondary

R. Amita, M.D.
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Cite this page: Amita R. Primary and secondary dilated cardiomyopathy. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/heartdilated.html. Accessed September 26th, 2023.
Definition / general
  • Dilated cardiomyopathy (DCM) is characterized by a poorly contracting dilated left ventricle with a normal or reduced left ventricular wall thickness
  • DCM is the most common cause of congestive cardiac failure (CCF), with an estimated prevalence of at least 36.5 per 100,000 persons in the USA
  • It occurs more frequently in men than women and is most common between ages 20 and 60 years
  • In most cases, no definite cause is identifiable
  • Most prevalent toxic cause is alcohol
  • Single gene mutations involve:
    • Structural proteins: dystrophin, metavinculin, lamin
    • Mitochondrial DNA
  • Coronary artery disease
  • Infections: coxsackievirus, adenovirus, parvovirus, HIV, bacterial, fungal rickettsial, myobacterial and parasitic (Chagas disease)
  • Nutritional deficiency: carnitine selenium deficiencies
  • Cardiotoxins (anthracycline)
  • Puerperium
  • Metals (cobalt, lead, mercury, arsenic)
  • Autoimmune and systemic disorders
  • Pheochromocytoma
Clinical features
  • Shortness of breath, syncope, angina
  • Complete blood count
  • Metabolic panel
  • Thyroid function tests
  • Cardiac biomarkers
  • B type natriuretic peptide assay
  • Chest radiography
  • Echocardiography
  • Cardiac magnetic resonance imaging (MRI)
  • Electrocardiography (ECG)
Case reports
  • Essentially the same as treatment of chronic heart failure (CHF)
Gross description
  • The heart assumes a globular shape and there is pronounced ventricular chamber dilatation, diffuse endocardial thickening and atrial enlargement, often with thrombi in the appendages
Gross images

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Ventricles dilated more than atria

Microscopic (histologic) description
  • Increase in myocyte nuclear size
  • Myofibrillary loss within myocyte
  • Focal myocyte death
  • Increase in interstitial T lymphocytes / macrophages
  • Interstitial fibrosis
  • The individual myocytes are increased in length rather than in width, lose the normal number of intracellular contractile myofibrils and appear empty and vacuolated
  • The myocyte nuclei increase in size because of the synthesis of DNA and become polyploid
  • Death of individual myocytes occurs both by apoptosis and necrosis
  • Fibrosis characteristically is interstitial and begins to surround and isolate individual myocytes
  • The number of macrophages and T lymphocytes in the interstitial spaces is often increased compared with normal hearts
Microscopic (histologic) images

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Cardiomyocyte multinucleation

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Adenomatous hyperplasia

Molecular / cytogenetics description
  • The pattern of inheritance of familial DCM (FDCM) is variable and includes autosomal dominant, X linked, autosomal recessive and mitochondrial
  • Autosomal forms of FDCM are the most frequent
    • Pure DCM phenotype: mutations of genes encoding cardiac actin, desmin, d-sarcoglycan, b-sarcoglycan, cardiac troponin T, tropomyosin
    • DCM with cardiac conduction system disease: lamin A/C gene
    • Autosomal dominant Emery-Dreifuss muscular dystrophy
  • The X linked forms of DCM includes X linked dilated cardiomyopathy and Barth syndrome
    • Caused by mutations in the dystrophin gene
    • X linked dilated cardiomyopathy (XLCM) occurs in males during adolescence or early adulthood and has a rapidly progressive clinical course
    • Female carriers develop a mild form of DCM with onset in middle age
    • Creatine kinase levels are elevated but without clinical signs of skeletal myopathy
  • The infantile form of X linked DCM or Barth syndrome typically presents in male infants
    • It is characterised by neutropenia, 3-methylglutaconic aciduria, growth retardation and mitochondrial dysfunction
    • The cardiac manifestations include left ventricular dilatation, endocardial fibroelastosis or a dilated hypertrophied left ventricle
    • Mutations in the gene G4.5, which encodes the protein tafazzin, cause Barth syndrome
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