Abstract 9370: Myocardial Tissue Characterization of Pediatric Patients With Duchenne Muscular Dystrophy

Abstract

Introduction: Cardiomyopathy (CM) is the leading cause of death in Duchenne muscular dystrophy (DMD). Cardiac magnetic resonance (CMR) parametric mapping sequences, Native T1, T2, and extracellular volume (ECV), can offer insights into disease pathophysiology. The objective of this abstract was to leverage parametric mapping sequences to define the tissue characteristics of DMD CM progression. We hypothesized DMD subjects could be categorized based on fibrosis, myocardial edema, and fat infiltration. Methods: DMD patients (n=52; median 12.1 years) underwent CMR including T1, T2, and ECV at the base, mid, and apex. Categories were defined as normal, early fibrosis (normal ECV, high T1, normal T2), fibrosis (high ECV, normal or high T1, normal T2), edema (normal or high ECV, normal or high T1, high T2), fat (normal ECV, low T1, high T2) or fibrofatty (high ECV, normal or low T1, high T2). Statistical analysis included Chi-square, Wilcoxon rank sum, Wilcoxon signed rank, and Spearman’s rho. Results: Median left ventricular ejection fraction (LVEF) was 59% and 15 (29%) had LVEF < 55%; 18 subjects (35%) had normal LVEF and no late gadolinium enhancement. These subjects were younger (10.2 years [8.4,11.6] vs 14.7 [11.5,17.8], p<0.001). Native T1 was elevated in at least one slice in 42 (81%). Patients with high T2 at any slice (n=13) were older (p=0.009) and had lower LVEF (p=0.009) compared with normal T2 (n=39). The most common stratifications (Figure 1) were early fibrosis (n=14) and fibrosis (n=21). Of the 13 with high T2, 9 were categorized as edema, 2 as fibrofatty, and 2 as fat. T2 at the base, mid, and apex increased from first to second CMR (all p<0.05) and T2 at mid and apex correlated with age (rho=0.2 and rho=0.38, p<0.05). Conclusion: Myocardial fibrosis is common in DMD. CM progresses with age and higher T2 suggesting fatty/fibrofatty infiltration. CMR parametric mapping sequences offer insights into disease pathophysiology, which should drive therapeutic innovation.