Elevated Myocardial Extracellular Volume Fraction in Duchenne Muscular Dystrophy

Abstract

Duchenne muscular dystrophy (DMD) is a genetic, X-linked recessive disease with an associated cardiomyopathy characterized by myocardial fibrosis leading to heart failure, arrhythmias, and death. Earlier detection and treatment of cardiac involvement in DMD hold potential to improve outcomes. Cardiovascular magnetic resonance (CMR) extracellular volume (ECV) quantification using T1 mapping is a histologically validated, non-invasive marker of diffuse fibrosis. This study aims to determine the ECV in a pediatric DMD population, and correlate it with metrics of left ventricular function. A retrospective review of pediatric DMD subjects who underwent CMR at a single institution. A total of 47 DMD patients (mean age 14 ± 2 years) were included for analysis. Global myocardial ECV was significantly higher in the DMD group (29 ± 6%) compared with published normal values (24 ± 2%, p = 0.0001). Higher ECV values correlate with indices of left ventricular function, including decreased left ventricular ejection fraction (r = -0.46, p = 0.001) and indexed left ventricular end diastolic volume (r = 0.41, p = 0.004). ECV was not significantly higher in DMD patients with late gadolinium enhancement (LGE) (30 ± 7%) compared to DMD patients without LGE (27 ± 5%, p = 0.0717). CMR T1 mapping is a feasible method for quantification of ECV in patients with DMD. Global myocardial ECV is significantly higher in the DMD population compared to healthy controls and correlates with other metrics of myocardial function. Global myocardial ECV may serve as an important tool to determine cardiac involvement in DMD population and help guide medical management.

Keywords: Duchenne muscular dystrophy cardiomyopathy; Heart failure; Late gadolinium enhancement; Magnetic resonance imaging; Myocardial fibrosis.