Abstract 14890: Diagnosing Duchenne Muscular Dystrophy-Associated Cardiomyopathy: Echocardiogram Shoots, Cardiac Magnetic Resonance Imaging Scores

Background: Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disorder characterized by progressive muscle degeneration. The leading cause of death is complications from the development of DMD-associated cardiomyopathy. The majority of DMD patients have skeletal abnormalities that limit the quality of echocardiograms (ECHO). Although cardiac magnetic resonance imaging (cMRI) is the gold standard cardiac imaging tool, the vast majority of DMD patients are evaluated by ECHO rather than cMRI. We hypothesized that when compared to ECHO, cMRI more accurately assesses cardiac function and provides more valuable data for the diagnosis of DMD-associated cardiomyopathy. Methods: We undertook a retrospective study of 20 DMD patients referred to the UT Southwestern Adult Neuromuscular Cardiomyopathy Clinic who had undergone both an ECHO and cMRI within 15 months of each other. We assessed the proportion of studies demonstrating reduced left ventricular (LV) function [cMRI LVEF<62%, ECHO fractional shortening (FS)<25%] and that were technically difficult by both techniques. In addition, we assessed the proportion of cMRIs with late gadolinium enhancement (LGE), a marker of myocardial fibrosis and associated with increased mortality. Results: Amongst these patients, 10% of cMRIs and 85% of ECHOs were technically difficult. By cMRI, 30% of the studies were normal (LVEF 64±2 %), while 70% showed reduced function (LVEF: 44±12%). By ECHO, 75% of the studies were normal (FS 32±5), while 25% showed reduced function (FS: 15±8). Of the patients with truly reduced function by cMRI, 64% were considered normal by ECHO. Finally, 61% of cMRI studies showed LGE (50% with normal LVEF and 67% with reduced LVEF). Conclusions: In summary, cMRI is superior to ECHO in assessing cardiac function in DMD. ECHO underestimates left ventricular dysfunction, likely due to the poor quality of studies obtained in this patient population. In addition, cMRI identifies LGE, a marker associated with increased mortality, irrespective of cardiac function. Earlier utilization of cMRI will expedite the diagnosis of DMD-associated cardiomyopathy and enable the cardiologist to initiate aggressive guideline-directed medical therapy at an earlier age.