At 4 years old, a male infant was diagnosed with progressive muscular dystrophy. His heart functions, however, were not examined. Although he had general fatigue and limb weakness at the time of entry to a junior high school, there were no major problems in daily life. At 12 years old nine months, liver dysfunction became evident, which led to diagnosis of dilated cardiomyopathy complicated by liver dysfunction. He was transferred to the ICU of our hospital due to deteriorating heart failure. Because the heart failure was intractable to medication after ICU admission, we implanted ventricular assist devices. However, subsequent to infection, the patient died from multiple organ failure 33 days after ICU admission. To enable the earliest detection and treatment of cardiomyopathy, for patients who present symptoms of myopathy, it is important to specify the type of myopathy and to periodically evaluate cardiac function. As long as there are no apparent contraindications, such as respiratory muscle paralysis, it is possible to apply ventricular assist devices or cardiac transplantation to these patients.