Steroid therapy effectively delays Duchenne's cardiomyopathy.

Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is caused by a defective gene located on the X chromosome responsible for dystrophin production. The vast majority (70% to 85%) of dystrophin mutations are deletions; point mutations in the coding sequence or the splicing site account for the remainder (1). Significant associations between dilated cardiomyopathy and dystrophin mutations in exons 12 and 14 and possible protection against dilated cardiomyopathy by exon 51 and 52 mutations have been reported (2). Cardiac involvement is universally present in the disorder and typically manifests itself in the form of dilated cardiomyopathy or arrhythmias. Dystrophin normally provides mechanical reinforcement to the sarcolemma and stabilizes the glycoprotein complex by linking actin at the aminoterminus to the dystrophin-associated protein complex and sarcolemma at the carboxyl-terminus. Its absence results in a fragile cellular membrane that is more easily damaged during repetitive muscle contractions. This results in the development of myocyte necrosis and subsequent fibrosis leading to progressive ventricular dilation and failure (1). ystrophin is also an important component of the memrane in Purkinje fibers; thus, conduction disease and rrhythmias are not uncommon in the condition (1). Alhough progressive respiratory failure is the most common ause of mortality in DMD, heart failure accounts for 25% of all deaths (1). DMD cardiomyopathy is characerized by extensive fibrosis and thinning of the ventricular all. Disproportionate scarring occurs early in the posteroateral left ventricular wall. As the disease progresses, yocardial fibrosis also spreads to the remaining walls. Left ventricular dysfunction is usually present by 10 to 12 ears of age and nearly universal by the late teenage years. chocardiography, particularly using tissue characterization,