Heart Muscle Diseases (Cardiomyopathies): Classification

In addition to mixed and transitional forms, five main forms of cardiomyopathy are distinguished – classification according to WHO (World Health Organization):

• Dilated (dilated) cardiomyopathy (DCM; ICD-10 I42.0) – Systolic pump dysfunction with cardiomegaly (enlargement of the myocardium (heart muscle)) and impaired ejection fraction (EF; ejection fraction).
  • Only the right ventricle or the left ventricle may be affected, but both ventricles may be affected.
  • In addition, disorders of diastolic function are present, i.e. delayed and incomplete relaxation of the myocardium and stiffening of it.
  • Effects: Due to the dilation of the ventricles, the heart can not adequately contract and transport blood to the systemic circulation.
• Hypertrophic (enlarged) cardiomyopathy (HCM; ICD-10 I42.2: Other hypertrophic cardiomyopathy) – The thickness of the heart muscle, especially the left ventricular wall, increases.
  • Diastolic distensibility disorder of the thickened myocardium.
  • The left ventricle is affected, occasionally also the right ventricle
  • With and without obstruction (narrowing) of the left ventricular outflow tract:
    • Hypertrophic nonobstructive cardiomyopathy (HNCM; ICD-10 I42.2) – approximately one-third of cases.
    • Hypertrophic obstructive cardiomyopathy (HOCM; synonym: Idiopathic hypertrophic subaortic stenosis (IHSS); ICD-10 I42.1) – approximately two-thirds of cases; the muscles of the left ventricle, particularly the ventricular septum (ventricular partition), thicken.
    • Note: Since approximately 30-40% of patients without obstruction at rest develop obstruction under stress, provocation tests are required to distinguish the two subtypes HNCM and HOCM!
• Restrictive (restricted) cardiomyopathy (RCM; ICD-10 I42.5) – stiffening of the ventricular walls due to scarring of muscle tissue or deposition of amyloids (proteins/proteins)
  • Decrease in diastolic distensibility, mostly of the left ventricle.
  • In the relaxation phase, the heart can not fill with enough blood.
  • The pumping function is not disturbed.
  • Normal or only slightly thickened wall thickness of the myocardium (differentiation from HCM!).
  • Early stage: often unexplained heart failure (cardiac insufficiency)-symptomatic with large atria and largely preserved systolic ventricular function (demarcation from DCM!).
  • In advanced stages, the walls of the endocardium (inner lining of the heart) are thickened and covered with thrombi (blood clots).
  • Very rare disease
  • Forms of restrictive cardiomyopathy:
    • Myocardial forms
      • Noninfiltrative RCM
        • Idiopathic (with no identifiable cause).
        • Familial
        • RCM in scleroderma (group of rare diseases associated with leathery connective tissue hardening of the skin).
      • Infiltrative RCM – e.g., in amyloidosis (accumulation of abnormally altered proteins outside cells), sarcoidosis (systemic disease of connective tissue with granuloma formation (skin, lungs, and lymph nodes)).
      • RCM in storage diseases – hemochromatosis (iron storage disease), Fabry disease (X-linked recessive inherited metabolic disease belonging to the group of lysosomal storage diseases; is based on a defect in the gene for the enzyme alpha-galactosidase A; untreated, it comes in the further course to heart and kidney damage; prevalence (disease frequency): 1:117,000).
    • Endomyocardial forms
      • Endomyocardial fibrosis (in Africa).
      • Hypereosinophilia (Löffler endocarditis).
      • Carcinoid (endocardial fibrosis, especially of the right heart (Hedinger syndrome)).
• Arrhythmogenic right ventricular cardiomyopathy (ARVCM; synonyms: Arrhythmogenic right ventricular dysplasia cardiomyopathy; ARVD; ARVC ; ICD-10 I42.80) – the musculature of the right ventricle is altered
  • Breakdown of myocytes (muscle cells) in the right ventricle and replacement of these with lipocytes (fat cells) and/or fibroblasts (connective tissue cells)
  • The result is dysfunction or dilatation.
  • Right ventricular combined pumping defect may cause ventricular tachycardia (heartbeat too fast; > 100 beats per minute).
• Nonclassifiable cardiomyopathy (NKCM).
  • Collection of various disorders, e.g.:
    • Isolated (ventricular) noncompaction cardiomyopathy (NCCM).
      • Congenital (congenital) disease of the left ventricular myocardium.
      • Occurs sporadically or familially
      • May be associated with other cardiac abnormalities