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Cardiomyopathy in Duchenne Muscular Dystrophy

Cardiac abnormalities are a significant cause of death and morbidity in patients with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), especially as boys with DMD are now living through their twenties. The clinical course of cardiomyopathy is usually prolonged (progressive decline in left ventricular function resulting in cardiac failure) although sudden death from an arrhthymia also occurs. Many patients do not show symptoms of cardiomyopathy due to their lack of physical activity, but early changes in cardiac function are apparent on cardiac imaging studies, such as an echocardiogram or cardiac magnetic resonance imaging study (MRI). Because changes in cardiac function are uncommon before the second decade of life, the Treat-NMD standards recommend a cardiology evaluation with an echocardiogram and electrocardiogram (ECG) at the time of diagnosis, then biannually until age 10 years, and annually thereafter unless progressive problems suggest the need for more frequent exams. Standards of Care for Duchenne Muscular Dystrophy (TREAT-NMD) A cardiology referral is also recommended before any major surgery. Clinical symptoms, when present, may include symptoms of congestive heart failure (edema, shortness of breath, orthopnea) and/or reduced cardiac output (especially fatigue) and/or arrhythmias. However symptoms might not be present due to decreased skeletal muscle strength and subsequent decreased physical activity until very late in the course of the disease. With severe cardiomyopathy, thromboembolic events are sometimes observed.
Of note, the mothers of boys with DMD/BMD may also be at risk for cardiac problems and should be evaluated by genetic testing to confirm carrier status, and an ECG and echocardiogram should be performed by an adult cardiologist.
An ECG and echocardiogram will usually be performed at cardiology evaluations. Some cardiologists may perform a cardiac MRI instead of or in addition to an echocardiogram for better visualization of the heart in patients with poor echocardiographic images. Cardiac MRI also allows assessment of the extent of scarring of the heart muscle, which cannot be done with an echocardiogram. Decreased left ventricular ejection fraction on echocardiogram is the most common early finding and signals the onset of dilated cardiomyopathy.
Management involves diagnosis and treatment as early as possible based on echocardiographic findings and not clinical deterioration. Initial medications used include angiotensin converting enzyme (ACE) inhibitors such as enalapril or lisinopril, and angiotensin receptor blockers (ARBs), such as losartan. These medications are also commonly used to treat high blood pressure that may be associated with steroid therapy in boys with DMD. Other agents, such as beta-blockers, may be added with progression of dilated cardiomyopathy depending on cardiology preference and disease manifestations. Other medications, such as diuretics, may be added when the patient has evidence of congestive heart failure. Anti-arrhthymic therapy is sometimes needed. Left ventricular assist devices (LVADs) may increasingly be offered to boys in heart failure and in some, transplantation may be a possibility. There is also recent evidence suggesting that prolonged steroid therapy may be helpful in delaying the onset of cardiomyopathy. [Schram: 2013]

Resources

Practice Guidelines

TREAT-NMD, a neuromuscular network, has published a list of expert guidelines, including cardiology recommendations. See Standards of Care for Duchenne Muscular Dystrophy (TREAT-NMD)

Bushby K, Bourke J, Bullock R, Eagle M, Gibson M, and Quinby J.
The multidisciplinary management of Duchenne muscular dystrophy.
Current Paediatrics. 2005;15:292-300. / Full Text

Helpful Articles

PubMed search on Duchenne muscular dystrophy: review articles over the last 5 years

Jefferies JL, Eidem BW, Belmont JW, Craigen WJ, Ware SM, Fernbach SD, Neish SR, Smith EO, Towbin JA.
Genetic predictors and remodeling of dilated cardiomyopathy in muscular dystrophy.
Circulation. 2005;112(18):2799-804. PubMed abstract

Ramaciotti C, Heistein LC, Coursey M, Lemler MS, Eapen RS, Iannaccone ST, Scott WA.
Left ventricular function and response to enalapril in patients with duchenne muscular dystrophy during the second decade of life.
Am J Cardiol. 2006;98(6):825-7. PubMed abstract

Duboc D, Meune C, Pierre B, Wahbi K, Eymard B, Toutain A, Berard C, Vaksmann G, Weber S, Bécane HM.
Perindopril preventive treatment on mortality in Duchenne muscular dystrophy: 10 years' follow-up.
Am Heart J. 2007;154(3):596-602. PubMed abstract

Authors

Authors: Richard Williams, MD - 9/2013
Lynne M Kerr, MD, PhD - 9/2013
Content Last Updated: 8/2009

Page Bibliography

Schram G, Fournier A, Leduc H, Dahdah N, Therien J, Vanasse M, Khairy P.
All-cause mortality and cardiovascular outcomes with prophylactic steroid therapy in Duchenne muscular dystrophy.
J Am Coll Cardiol. 2013;61(9):948-54. PubMed abstract