Cardiac affliction in hereditary muscle diseases

The clinical picture of a number of heredofamilial neuromuscular diseases includes also cardiac affliction. In relation to the site of pathological changes the cardiac affection may be manifested as a cardiomyopathy, depending on the severity of the disorder, progressing to congestive heart failure, or conduction disorders and arrhythmias which may lead to sudden cardiac death. In some heredofamilial muscular diseases there is a combination of both types of cardiac affection. In the second part of the summary we shall focus attention on the nature of the cardiac affection in myotonic dystrophy, sarcoglycanopathies and Emery-Dreifuss muscular dystrophy. Myotonic dystrophy is the most frequent muscular dystrophy of adult age and cardiac affection is often part of this multiorgan disease which has a marked impact on the mortality and morbidity of the patients. Most frequently conduction disorders and atrial arrhythmias are encountered, less frequently fatal ventricular tachyarrhythmias and cardiomyopathies are described. The severity of cardiac, similarly as neuromuscular affection, correlates according to some studies significantly with the extent of the molecular genetic defect. Accurate data on the extent and nature of cardiac affection in sarcoglycanopathies have not been defined exactly so far. The association of alpha-sarcoglycan deficiency and dilatation cardiomyopathy seems important. Emery-Dreifuss muscular dystrophy holds a special position among muscular dystrophies due to its dominant cardiac affection which dominates over myopathy and contractures, two other basic symptoms of this syndrome. Cardiac affection has most frequently the character of atrial dysrrhythmias and conduction disorders, the most serious clinical manifestation being complete atrioventricular block. The high frequency of sudden cardiac death emphasizes the necessity of correct and early diagnosis of this disease.