Cardiac involvement in hereditary muscle diseases

The clinical picture of a number of hereditary familial neuromuscular diseases includes cardiac affections. Depending on the type of muscular dystrophy the pathological changes may dominantly affect the cardiac musculature or the specialized tissue of the cardiac conduction system. If the cardiac chambers are affected cardiac disease is manifested as a cardiomyopathy, depending on the severity of the disorder progressing to congestive heart failure. If the maximum of pathological changes is present in tissues of the cardiac conduction system, in the clinical picture dominate conduction disorders and arrhythmias which may lead to sudden cardiac death. In some heredofamilial muscular diseases we find a combination of both types of cardiac affection. Heredofamilial muscular diseases which are characterized in addition to affection of skeletal muscles also by cardiac affection include muscular dystrophies with defective synthesis of dystrophin and dystrophin associated glycoproteins, myotonic dystrophies, Emery-Dreifuss muscular dystrophy and some mitochondrial diseases. In Emery-Dreifuss muscular dystrophy, myotonic dystrophy and some types of dystrophinopaties the cardiac affection may be the first and/or dominant manifestation of the disease. In the first part of the review the authors describe the affection of the heart in dystrophinopathies, where the cardiac disease is a uniform part of all basic types of the disease. Dilating cardiomyopathy predominantes, the hypertrophic form and cardiac dysrhythmia are found less frequently. An exception are female carriers where the prevalence of hypertrophic cardiomyopathy is three times as frequent as the prevalence of the dilating form. The incidence of preclinical and clinical cardiac affection progresses with the duration of the disease and correlates indirectly with the functional demands on cardiac musculature which depends on the severity of affection of the skeletal musculature, Therefore the prevalence of clinically severe cardiomyopathies is higher in mobile patients (Becker's form of dystrophinopathy) than in patients confined to a wheelchair already in the early stages of the disease (Duchenne's form). A special form is X-linked dilating cardiomyopathy: it is mostly an isolated affection of the heart with no or minor affection of the skeletal muscles. The patients with all types of dystrophinopathiess should have regular cardiological check-ups. Conversely examination for dystrophinopathies should be in young patients of both sexes with idiopathic cardiopathies (dilatation and hypertrophy) a standard part of the diagnostic algorithm.