This single center open-label pilot study will enroll 15 non-ambulatory children with Duchenne muscular dystrophy at least 8 years of age and who demonstrate pre-clinical cardiomyopathy (defined as a cardiac ejection fraction \>55% with abnormal LV strain by cardiac MRI). They will receive (+)-epicatechin at one of three doses during an 8-week dose-ranging study with assessments at baseline, 2 Weeks, 4weeks, and 8 weeks. The study will determine optimal dosing for future cardiac efficacy studies based on serum / plasma biomarker response using follistatin: myostatin ratio, nitrite/nitrate ratio, cardiac troponins and cardiac BNP. Secondary endpoints will include additional biomarker assessments by SOMAscanTM, cardiac functional evaluations by cardiac MRI (LV strain), and echocardiogram (LV strain by speckle tracking) and measures of strength, range of motion and mobility, and clinical safety assessments. Results of secondary endpoint analysis will be used to refine design of subsequent clinical trials powered to detect changes in clinical outcomes.