Cardiac disease is the major cause of mortality in patients with muscular dystrophy and is present in most boys with Duchenne muscular dystrophy and approximately 70 % of those with Becker muscular dystrophy. These are the two common forms of muscular dystrophy caused by defects in a gene called dystrophin. Both are frequently associated with dilated cardiomyopathy (DCM), heart failure and premature death.
Cardiac symptoms typically appear late in the course of cardiomyopathy, in part because affected individuals are usually wheelchairchair bound and often physically inactive. Heart disease progresses quickly, leading to premature death, often before 25 years of age.
According to new research published online (October 24, 2005) in the journal Circulation, early diagnosis and treatment of DCM in DMD/BMD patients may lead to ventricular remodeling and that specific dystrophin gene mutations may predict cardiac involvement, while other mutations may protect against or inhibit development of DCM.
For the study, 69 boys, 62 with DMD and 7 with BMD were referred to the Cardiovascular Genetics Clinic for evaluation, including echocardiography and DNA analysis. Follow-up evaluations were scheduled yearly until the first abnormal echocardiogram indicative of DCM and quarterly thereafter. After the first abnormal echocardiogram, which occurred at 14-15 years, 31 boys were started on ACE inhibitor or beta blocker therapy. During the follow-up two patients remained stable with their dilated cardiomyopathy, eight showed improvement and 19 normalized both heart size and function.
The authors, from the Baylor College of Medicine (BCM) and Texas Children's Hospital in Houston add that further studies evaluating the impact of early intervention strategies on left ventricular geometry and function in muscular dystrophy patients seem warranted.