Duchenne Muscular Dystrophy: Cardiac Management

Introduction Aim: early detection and treatment of deterioration in heart muscle function Cardiac disease most often manifests as – Cardiomyopathy and/or – Cardiac arrhythmia Progressive cardiomyopathy a major source of DMD/BMD morbidity – warrants further study – Clear onset of disease in myocardium before clinical symptoms – Surveillance and proactive management are key: a cardiologist must be in the care team Family should have a copy of the latest assessments to show attending doctors

Surveillance: Baselines Baseline evaluation of cardiac function at diagnosis or by 6 years at the latest, especially if possible without sedation – Clinical judgement should be used for patients under 6 requiring sedation – Incidence of echocardiograph abnormalities is low in children under 8-10 years, but where they do exist can affect clinical decision-making – Baseline echocardiogram also allows for screening for anatomical abnormalities(e.g. atrial/ventricular septal defects, patent ductus arteriosis) which may affect long-term cardiovascular function Minimal evaluation should include, but is not limited to, and electrocardiogram (ECG) and echocardiogram

Surveillance: Annual Evaluation Evaluation at least once every 2 years to the age of 10. Annual complete cardiac assessments should begin at 10, or at onset of cardiac signs or symptoms if these occur earlier Increased surveillance (at least every 6 months) required if non-invasive cardiac tests show abnormalities of ventricular function. – Drug treatment should be initiated, irrespective of the age at which they are detected

Treatment First-line therapy: angiotension converting enzyme (ACE) inhibitors Beta-blockers and diuretics also appropriate, and should follow published guidelines for management of heart failure Recent clinical trial evidence supports the prophylactic treatment of cardiomyopathy with ACE inhibitors prior to signs of abnormal functioning: further studies awaited to allow firm recommendations.

Abnormalities (1) Abnormalities of cardiac rhythm should be promptly investigated with Holder or event monitor recording, and should be treated Sinus tachycardia is common in DMD, but also noted in systolic dysfunction. – New onset in absence of clear cause should prompt assessment including that of left-ventricular function Those on steroids need additional cardiovascular attention, especially for hypertension which may necessitate an adjustment of steroid dose [TLN table 2 part 1]

Abnormalities (2) Systemic arterial hypertension should be treated Prevention of systemic thromboembolic events by anticoagulation therapy can be considered in severe cardiac dysfunction, but inappropriate in earlier cardiac dysfunction Usefulness of internal cardiac defibrillator not established With generally improved fitness of DMD patients, cardiac transplants may require consideration in future

References & Resources The Diagnosis and Management of Duchenne Muscular Dystrophy, Bushby K et al, Lancet Neurology (1) & Lancet Neurology (2) – Particularly references, p The Diagnosis and Management of Duchenne Muscular Dystrophy: A Guide for Families TREAT-NMD website: CARE-NMD website: