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McMaster Textbook of Internal Medicine

Cardiomyopathies

How to Cite This Chapter: Da C.Z. Borjaille C, Demers C, Connolly K, Wodniecki J, Leśniak W. Cardiomyopathies. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. https://empendium.com/mcmtextbook/chapter/B31.II.2.16. Accessed December 05, 2025.
Last Reviewed: June 3, 2025
Last Updated: June 3, 2025
Chapter Information

Definition and ClassificationTop

Cardiomyopathies are myocardial disorders in which the myocardium is structurally and functionally abnormal in the absence of significant coronary artery disease, hypertension, valvular heart disease, or congenital heart disease. These 4 conditions can cause left ventricular (LV) dysfunction from ischemia, infarction, volume overload, or pressure overload and are excluded from the classification scheme of cardiomyopathies by the European Society of Cardiology and the American Heart Association.

While classification schemes vary, cardiomyopathies are typically classified according to morphologic phenotypes, which can be further divided into familial or nonfamilial forms:

1) Dilated cardiomyopathy (DCM).

2) Hypertrophic cardiomyopathy (HCM).

3) Restrictive cardiomyopathy (RCM).

4) Arrhythmogenic right ventricular cardiomyopathy (ARVC).

5) Nondilated left ventricular cardiomyopathy (NDLVC).

6) Unclassified cardiomyopathy.

The diagnosis of cardiomyopathies has several limitations. For this reason the European Society of Cardiology described a new category of cardiomyopathies characterized by the presence of nonischemic LV scarring or fatty replacement, regardless of the LV function and without LV dilatation. Such patients should now be classified as having NDLVC.

Each of the above 6 types of cardiomyopathies can be further classified as:

1) Familial (genetic) cardiomyopathy: Occurrence in ≥1 family member of a phenotype caused by the same genetic mutation or a de novo mutation in an index patient that can be transmitted to offspring, which is seen in Mendelian inheritance. There is also evidence of polygenic inheritance, where multiple genetic variants can determine susceptibility to a phenotype.

2) Nonfamilial (nongenetic) cardiomyopathy: Either idiopathic (of an unknown cause) or acquired (associated with toxins, infections, other diseases).

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