A Case of Muscular Dystrophy with Dilated Cardiomyopathy: Do Not Forget Your Basics

Abstract

<h3>Introduction</h3> Becker muscular dystrophy (BMD) is an X-linked recessive disorder with dystrophin mutation. Dilated Cardiomyopathy (DCM) is a leading cause of death in BMD patients. Herein, we are presenting a patient with BMD that initially sought medical attention for acute onset of systolic heart failure that highlights the importance of careful clinical assessment and appropriate work up. <h3>Case Report</h3> A 29-year-old male with medical history of asthma presented to the hospital with progressive dyspnea and leg swelling. He was diagnosed with DCM with an LVIDD of 6.5 cm and LV ejection fraction of 20-25% by echocardiogram. Coronary angiogram revealed no coronary artery disease. Initial blood work and electrocardiogram are below (Figure). Cardiac MRI showed severely reduced biventricular systolic function with near circumferential, sub-epicardial to mid-myocardial delayed gadolinium enhancement (Figure). Initial differential diagnosis included prior myocarditis vs. burnt out sarcoidosis. It was subsequently noted that patient began recurrently falling with muscle weakness from age 20 years with chronically elevated AST and CK. His exam was notable for atrophy of the bilateral quadriceps muscles, decreased muscular strength and bilateral calves hypertrophy. Electromyography showed evidence of chronic proximal and distal myopathy, predominantly affecting the lower extremity. Skeletal muscle biopsy showed fascicular atrophy and hypertrophy, focal endomyosial fibrosis and an increase of central nuclei without evidence of inflammation or granuloma which was most suggestive of a muscular dystrophy. Genetic testing was then completed and showed hemizygous dystrophin mutation confirming diagnosis of BMD. <h3>Summary</h3> BMD has a diffuse phenotype and should be considered in young patients with cardiomyopathy and chronically elevated CK and AST. A thorough clinical history, exam, and CMR can assist in directing need for skeletal muscle biopsy and subsequent genetic testing.