The Preventive Efficacy of Carvedilol on Cardiac Dysfunction in Duchenne Muscular Dystrophy

Carvedilol for the Prevention of Minor Cardiac Damage and Cardiac Function in Duchenne Muscular Dystrophy

Purpose This cardiac dysfunction in patients with Duchenne muscular dystrophy is associated with minor cardiac damage as indicated by elevation of plasma cardiac troponin I (cTnI). The purpose of this study is to investigate whether the administration of Carvedilol can suppress the minor cardiac damage and prevent deterioration of cardiac function.

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.

Inclusion Criteria:

Male patients with Duchenne muscular dystrophy are required to meet the following criteria:

1. Aged ８ to 45 years
2. Positive plasma cardiac troponin I (0.06ng/mL) at least 4 blood measurement in every 3 month.
3. Left ventricular ejection fraction >30% by echocardiography assessment
4. Written informed consent

Exclusion Criteria:

Patients with the following conditions will be excluded from the study:

1. Left ventricular ejection fraction <30%
2. No plasma cTnI elevation
3. beta-blocker is already administered without measurement of plasma cTnI
4. Contraindication against treatment with β blockers
5. Any other serious disease that could potentially complicate the management and follow-up protocols