Imaging the heart to detect cardiomyopathy in Duchenne muscular dystrophy: A review

Duchenne Muscular Dystrophy is the most common paediatric neuromuscular disorder. Mutations in the DMD gene on the X-chromosome result in progressive skeletal muscle weakness as the main clinical manifestation. However, cardiac muscle is also affected, with cardiomyopathy becoming an increasingly recognised cause of morbidity, and now the leading cause of mortality in this group. The diagnosis of cardiomyopathy has often been made late due to technical limitations in transthoracic echocardiograms and delayed symptomatology in less mobile patients. Increasingly, evidence supports earlier pharmacological intervention in cardiomyopathy to improve outcomes. However, the optimal timing of initiation remains uncertain, and the benefits of prophylactic therapy are unproven. Current treatment guidelines suggest initiation of therapy once cardiac dysfunction is detected. This review focuses on new and evolving techniques for earlier detection of Duchenne muscular dystrophy-associated cardiomyopathy. Transthoracic echocardiography or cardiac magnetic resonance imaging performed under physiological stress (dobutamine or exercise), can unmask early cardiac dysfunction. Cardiac magnetic resonance imaging can define cardiac function with greater accuracy and reliability than an echocardiogram, and is not limited by body habitus. Improved imaging techniques, used in a timely fashion, offer the potential for early detection of cardiomyopathy and improved long-term outcomes.