[A case of Becker muscular dystrophy presenting cardiac failure as an initial symptom].

Was reported a 23-year-old man with Becker muscular dystrophy (BMD), manifesting heart failure as an initial symptom. He had admitted to a hospital because of his sudden exertional dyspnea due to dilated cardiomyopathy. Because of elevated serum CK level, he had admitted to our hospital for further clinical evaluation. His uncle and male cousin were affected by a mild progressive muscle weakness since second decades. Physically, his intelligence was slightly below the average (WAIS total IQ 71). There was a slight weakness in his pelvic and shoulder girdle muscles. Pseudohypertrophy was observed in calves and tongue. Serum CK level was markedly elevated to ten times of the upper normal limits. Both EMG and muscle biopsy examinations revealed mild myopathic changes. Electrocardiogram showed tall R waves in leads V1 and V2, abnormal Q waves in I, aVL, V5 and V6 and flattened T waves in V5 and V6. On immunostaining of the biopsied skeletal muscle, patchy appearance of dystrophin on the surface membrane of the fiber was detected, which is consistent with BMD. Myocardiac damages in BMD are not always related either to the duration or the severity of the skeletal muscle weakness, as shown in our present case. The possibility that subclinical BMD is one of causes for dilated cardiomyopathy always must be considered.