Cardiomyopathy in Muscular Dystrophy Workshop 28–30 September 2003, Tucson, Arizona

Neuroscience Letters, 2004

Clinical Recomendations:

The European Neuromuscular Centre convened a meeting in 2002 on Cardiomyopathy and Muscular Dystrophy. Kate Bushby presented the findings and recommendations from that gathering. At the 2002 meeting and the present meeting, it was agreed that clinical studies were not available to provide specific recommendations regarding the management of cardiomyopathy in muscular dystrophy. The rare nature of these disorders leads to difficulty in assembling sufficient numbers of subjects for controlled clinical trials. As such, multicenter-based trials are needed, and multicenter trials are just beginning. The complexity in conducting these trials also includes the determination of adequate endpoints and uniformity in performance and interpretation of noninvasive studies. Carolyn Spencer reviewed the use of echocardiography as a tool to predict outcome in subjects with cardiomyopathy. In some studies, left ventricular function has been used as an endpoint for studies of heart failure, and it may be useful for studies of the heart failure that accompanies muscle disease. Paula Clemons is working with Cooperative International Neuromuscular Research Group (CINRG) to begin a study of the efficacy of Co enzyme Q10 and prednisone in children with DMD. An arm of this study will evaluate the effect of these medications on cardiac function including wall stress, shortening fraction, and tissue Doppler imaging. Valerie Cwik discussed the ongoing MD STARNet study sponsored by the Centers for Disease Control. Its goals are to determine whether there has been a change in the prevalence of DMD and to determine what treatment is being offered to children with DMD. Until controlled clinical trials are available for cardiomyopathy with muscular dystrophy, recommendations for clinical care should rely on controlled clinical trials of heart failure and cardiomyopathy. The mainstay of pharmacologic treatment for left ventricular dysfunction for adults with cardiomyopathy and CHF relies on (1) afterload reduction with ACE inhibitors as a first line option and angiotensin receptor blockade if ACE inhibitors cannot be used, (2) beta adrenergic receptor blockade, (3) spironolactone, (4) diuretics as needed to manage fluid overload, and (5) aggressive surveillance for cardiac arrhythmias. The role of additional pharmacologic agents such as digoxin is not clear. Arrhythmias, if detected or suspected, can be treated by device implantation and/or pharmacologic therapy with antiarrhythmic agents. Surveillance should include regular EKGs, Holter monitoring and/or event monitoring. Syncope, if noted, may warrant treatment for presumed arrhythmias. Similar therapies in children, with the use of ACE inhibitors and b-blockers with or without diuretics and digoxin, are first line approaches. The specific recommendations may be modified with regard to the precise gene defect. In DMD, heart involvement generally occurs later than skeletal muscle involvement and may not be present until the late second decade. It is not known at this time whether early treatment, before the visible onset of left ventricular dysfunction may slow the course of cardiomyopathy. Future clinical trials should be designed to determine at what age and at what stage therapy to prevent cardiomyopathy should be initiated. As these problems can become evident in the early second decade, monitoring should begin at that time. Cardiologists, whether specialized in the care of adult or pediatric patients, should be experienced in caring for subjects with muscular dystrophy. The Muscular Dystrophy Association may wish to identify a referral base of cardiologists who work with the MDA clinics throughout the country. In BMD, cardiac involvement may occur later but may eventually become a prominent feature. Cardiac transplantation can be offered if pharmacologic therapy fails. Monitoring should begin in the late second decade for BMD. Finally, female carriers of dystrophin mutations should be evaluated beginning in their late 3rd to 4th decade since cardiomyopathy may develop in these subjects.