The Cardiomyopathy of Progressive Muscular Dystrophy

A prospective study was undertaken in order to examine the histories, physical signs, phonocardiograms, electrocardiograms, vectorcardiograms, X-rays, serum enzymes, pulmonary ventilatory findings, and hemodynamics in a group of 55 patients selected solely on the basis of one of the major types of progressive muscular dystrophy (table 9). The classification included: (1) the classic Duchenne type, (2) the limb girdle type, (3) the facioscapulohumeral type, and (4) a group of patients in whom clinical distinction between benign Duchenne dystrophy and limb girdle dystrophy with pseudohypertrophy could not be made. No patient had recognized heart disease prior to selection. Follow-up periods ranged from a few months to 5 years. The pertinent literature was extensively reviewed. In all groups clinical evidence of heart disease had to be interpreted in the context of the influence of the somatic musculoskeletal defects on "cardiac" symptoms, cardiovascular physical signs, and radiological appearance of the heart. On the other hand, convincing evidence of intrinsic heart disease-subtle to overt-was found in each of the major categories of progressive muscular dystrophy. Detection of cardiomyopathy was simplest and most frequent in the classic Duchenne group because of the highly characteristic features of the scalar electrocardiogram which might direct attention to the systemic myopathy prior to its clinical recognition. However, the presence of heart disease in patients with forms of dystrophy other than the classic Duchenne deserves particular emphasis. Evidence of cardiomyopathy in these latter forms varied from subtle quadruple gallop rhythms in the limb girdle and facioscapulohumeral groups to cardiomyopathic death in the benign Duchenne and limb girdle-pseudohypertrophic group. Currently available information on the heart in muscular dystrophy has as a rule depended upon retrospective studies, upon reviews of published reports of incompletely classified cases, upon discussions of individual cardiovascular features, or upon observations of individual types of dystrophy. The present prospective study was undertaken to obviate some of these shortcomings. Comprehensive assessment of a large and carefully classified group of dystrophic subjects has provided additional information regarding the clinical spectrum of dystrophic cardiomyopathy.