Duchenne muscular dystrophy (DMD), the most common muscular dystrophy, leads to skeletal and cardiac muscle damage. Treatment of pulmonary complications has improved survival; however, heart muscle disease or cardiomyopathy has emerged as a leading cause of death, typically by the third decade. Although myocardial changes begin early, clinically significant heart disease is rarely detected in the first decade of life. Consequently, DMD cardiomyopathy frequently goes unrecognized (and untreated) until advanced (and irreversible).