Cardiomyopathy is a chronic disease in which the heart muscle (myocardium) becomes abnormally enlarged, thickened and/or stiffened. As a result, the heart cannot contract or relax normally, and its ability to pump oxygenated blood to the body is insufficient to keep up with the body’s needs. In advanced stages of the disease, irregular heartbeats (arrhythmia) and heart failure may occur.
Cardiomyopathy is not a single, isolated disease; it is a term used to classify several separate diseases that affect the heart muscle. Cardiomyopathy is classified according to several criteria:
Primary or Secondary Cardiomyopathy
Primary cardiomyopathy refers to cases in which the disease is isolated to the heart. The disease occurs by itself or for unknown reasons (known as idiopathic cardiomyopathy).
Secondary cardiomyopathy refers to cases in which the disease occurs secondary to another known cause such as inflammation of the heart muscle (myocarditis) caused by a viral infection; exposure to certain toxins or chemotherapy drugs; or certain systemic disorders that affect the heart and other organs. These system-wide disorders include muscular dystrophies, lysosomal storage diseases, metabolic disorders and autoimmune diseases to name a few.
Ischemic or Non-Ischemic Cardiomyopathy
Ischemic cardiomyopathy is caused by lack of blood supply to the heart, usually resulting from coronary artery disease (hardening of the arteries). Ischemic cardiomyopathy most often occurs in adults.
Non-ischemic cardiomyopathy results from the abnormal structure and function of the heart muscle itself. Most cardiomyopathy in children is classified as non-ischemic.
Subtypes of Non-Ischemic Cardiomyopathy
Cardiomyopathy found in children and teens is divided into five types: dilated, hypertrophic, restrictive, arrhythmogenic right ventricular and left ventricular non-compaction cardiomyopathy.
Each type refers to the form of damage to the heart muscle. Some patients may be diagnosed with more than one type of cardiomyopathy or the diagnosis may even change from one type to another over time; this is called an undulating phenotype.
Dilated and hypertrophic cardiomyopathies are the most common forms, with restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and left ventricular non-compaction cardiomyopathy occurring less frequently in children.
For a good overview, CCF’s Understanding Pediatric Cardiomyopathy booklet and accompanying inserts provide basic information on causes, diagnosis, symptoms and treatment on the various forms of cardiomyopathy. In addition, the Pediatric Cardiomyopathy FAQ sheet can be downloaded for answers to frequently asked questions about the disease.