• The suppression of minor cardiac damage indicated as elevation of plasma cTnI [ Time Frame: 2 years ] [ Designated as safety issue: Yes ]
  

• Left ventricular function deterioration assessed by echocardiography In-hospital mortality for cardiac dysfunction In-hospital mortality for any cause Overall mortality [ Time Frame: 5 years ] [ Designated as safety issue: No ]
  

The life span in patients with Duchenne muscular dystrophy has been extending due to the development of artificial respiratory devices. According to that, the ratio of cardiac dysfunction as a cause of death has been increasing. This cardiac dysfunction was associated with minor cardiac damage as indicated by elevation of plasma cardiac troponin I (cTnI). Furthermore, and the detection rate of cTnI plasma as revealed to be correlated with the deterioration speed of LV dysfunction assessed by serial echocardiography measurements. Accordingly, if this minor cardiac damage is suppressed, it is postulated that the progression of cardiac dysfunction can be stopped. In the cases with ventricular arrhythmia and tachycardia, we found plasma cTnI became undetectable after administration of beta-blocker. Accordingly, we investigate whether administration of beta-blocker, carvedilol can persistently suppress the minor cardiac damage and lead to suppress the deterioration of LV function. Note that his study preventive study for preserved to moderate LV dysfunction and is not intended to the beta-blocker treatment for severe LV dysfunction. Because we assume that the mechanism of elevation of cTnI is different; spontaneous in preserved to mild LV dysfunction in patients but LV wall stress in severe LV dysfunction in patients with Duchenne muscular dystrophy.