Abstract 2498: Minor Myocardial Damage and LV Dysfunction in Patients with Duchenne Muscular Dystrophy-The Preventive Efficacy of Carvedilol on Plasma Cardiac Troponin I-
Background: Cardiac dysfunction is one of the major prognostic factors in patients with Duchenne muscular dystrophy (DMD). Minor myocardial damage assessed by plasma cardiac troponin I (cTnI) is often observed in patients with DMD. However, it is unclear that how the minor myocardial damage occurs to which patient with DMD and how it relates to LV dysfunction. Therefore, we assessed the hypothesis that minor myocardial damage is associated with LV dysfunction, the evaluation of plasma cTnI helps the prediction of LV functional deterioration, and carvedilol prevents elevation of plasma cTnI in patients with DMD.
Methods: Plasma cTnI were repeatedly (every 3 months) measured for 2 years and LV function was assessed by echocardiography in 58 patients with DMD. Carvedilol (2.5–5 mg/day) was orally administered for a year to the patients who have shown plasma cTnI elevation (positive cTnI, cut off 0.06ng/mL).
Results: There were 3 differential groups regarding the progression rate of LV systolic dysfunction, i.e. rapid (19% of total, LVEF < 50% in their 10th), slow (50% of total, LVEF > 50% in their 20 –30th), and unchanged group (31% of total, LVEF < 50% in their 20 –30th). The episode of positive cTnI was observed in 27 (46%) of total patients with DMD. LVEF was lower in patients with positive cTnI than that with negative cTnI (42 ± 2 vs. 52 ± 2%, p < 0.05). Positive cTnI was observed in all patients in rapid group, 84% of patients in slow group, and only 6% of patients in unchanged group. Fourteen differential dystrophin gene mutations were recognized in 48 patients but they were not associated with those 3 differential groups or patients with positive cTnI. Administration of carvedilol in 13 patients (LVEF 40 ± 3) decreased the cTnI detection rate (from 44 ± 5% to 26 ± 10%, p < 0.05), while it was unchanged in 14 patients (LVEF 41 ± 3) without carvedilol treatment (from 44 ± 7% to 39 ± 6%) during same observation period.
Conclusions: The elevation of plasma cTnI was associated with LV systolic dysfunction in patients with DMD. The prediction of LV dysfunction in patients with DMD may be feasible with combinations of age, LVEF, and plasma cTnI elevation. Carvedilol could be a new therapeutic strategy to prevent minor myocardial damage in patients with DMD.