Abstract 2549: Abnormal Myocardial Circumferential Strain Precedes Global Functional Decline in Duchenne Muscular Dystrophy: A Cardiac Magnetic Resonance Tagging Study Using HARP Analysis
BACKGROUND: Duchenne Muscular Dystrophy (DMD), an x-linked myopathy, is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (ϵcc) abnormalities would exist in DMD prior to global systolic functional abnormalities regardless of age or left ventricular ejection fraction (EF).
METHODS: We evaluated 33 DMD males undergoing clinical cardiac MRI. Comparison was made to 13 age-matched healthy volunteers. Standard imaging included short-axis cine stack, cine myocardial tagging and myocardial delayed enhancement (MDE). Cardiac functional analysis was performed using Medis MASS software. Tagged images of only the mid-LV were analyzed using HARP software. For analysis, DMD males were subdivided by age: < or > 10 years. All subjects < 10 years had normal EF (>55%); none exhibited MDE. Subjects >10 years were divided by MDE status and EF (>55% or <55%). Student’s t-test was used to test for differences between groups.
RESULTS: DMD subjects with normal EF had abnormal ϵcc at an early age (<10 years) compared to control subjects (p< 0.05). DMD subjects >10 years with normal EF had further decline in =cc compared to younger DMD boys (p<0.05). There was further decline with age in =cc in subjects with lower EF (p<0.05) without MDE. In the oldest males studied with MDE and reduced EF, ϵcc was even lower (figure⇓).
CONCLUSIONS: Myocardial strain abnormalities are prevalent in the early stages of DMD existing in the setting of normal EF and progressing with advances in age. Such strain analysis may provide an early marker to guide the efficacy of preventive or gene therapy in DMD.