MRI-Based Circumferential Strain in Boys with Early Duchenne Muscular Dystrophy Cardiomyopathy

<b>Background:</b> In boys with Duchenne muscular dystrophy (DMD), cardiomyopathy has become the primary cause of death. Although both positive late gadolinium enhancement (LGE) and reduced left ventricular ejection fraction (LVEF) are late findings in a DMD cohort, LV end-systolic circumferential strain at middle wall (E_cc) serves as a biomarker for detecting early impairment in cardiac function associated with DMD. However, E_cc derived from cine Displacement Encoding with Stimulated Echoes (DENSE) has not been quantified in boys with DMD. We aim to: (1) use cine DENSE to quantify regional E_cc in LGE negative (-) boys with DMD and healthy controls; and (2) compare E_cc with LVEF in terms of differentiating DMD boys with LGE (-) from healthy boys. <b>Methods:</b> 10 LGE (-) boys with DMD and 12 healthy boys were enrolled prospectively in an IRB-approved study for CMR at 3T. Navigator-gated cine DENSE was used to obtain short-axis mid-ventricular data and estimate global and regional E_cc. Group-wise differences were tested via a Wilcoxon rank-sum test. Within-group differences were tested via a Skillings-Mack test followed by pairwise Wilcoxon signed-rank tests. A binomial logistic regression model was adopted to differentiate between DMD boys with LGE (-) and healthy boys. <b>Results:</b> When compared to healthy boys, LGE (-) boys with DMD demonstrated significantly impaired septal E_cc [-0.13 (0.01) vs. -0.16 (0.03), <i>p</i> = 0.019]. In comparison to the E_cc in other segments, both groups of boys exhibited significantly reduced septal E_cc and significantly elevated lateral E_cc. Septal E_cc outperformed LVEF in distinguishing DMD boys with LGE (-) from healthy boys. <b>Conclusions:</b> Reduced septal E_cc may serve as an early indicator of cardiac involvement in LGE (-) DMD boys prior to reduced LVEF and a positive LGE finding.