Myocardial metabolism in progressive muscular dystrophy.

YOCARDIAL as well as skeletal muscle lvi involvement occurs in a high proportion of cases of human progressive muscular dystrophy. This cardiac involvement constitutes a specific cardiomyopathy. Clinical evidence of myocardial involvement by the dystrophic process includes labile tachycardia in over 50 per cent of cases, congestive heart failure, various arrhythmias, cardiac murmurs, and cardiomegaly.1-5 Electrocardiographic abnormalities occur in up to 80 per cent of patients.3 These changes include sinus tachyeardia, bundle-branch block, premature ventricular contractions, shortened P-R intervals, T-wave changes, elevation of S-T segments, and abnormal Q waves.2 8 Pathologically, the myocardium shows the characteristic gross and histopathologic changes of skeletal muscle as seen in progressive muscular dystrophy, except that the myocardium is usually not so severely involved.3 7 In addition, specific cardiac lesions include increased subepieardial fat and occasional epicardial thickening.7 Subendocardial fibroelastosis may also occur." 9 The clinical findings and the pathologic changes of the heart in progressive muscular dystrophy have recently been reviewed by Levin, Baens and Weinberg.1 Although the metabolic changes of skeletal muscle in human progressive muscular dystrophy have been studied extensively, the metabolism of the myocardium has not been investigated. It is the purpose of this commu-