Left Ventricular Twist and Circumferential Strain from MRI Tagging Predict Early Cardiovascular Disease in Duchenne Muscular Dystrophy.

Duchenne Muscular Dystrophy (DMD) is a prevalent fatal genetic disorder, and heart failure is the leading cause of mortality. Peak left ventricular (LV) circumferential strain (E), twist, and circumferential-longitudinal shear angle (θ) are promising biomarkers for the improved and early diagnosis of incipient heart failure. Our goals were as follows: 1) to characterize a spectrum of functional and rotational LV biomarkers in boys with DMD compared with healthy age-matched controls; and 2) to identify LV biomarkers of early cardiomyopathy in the absence of abnormal LVEF or LGE. Boys with DMD ( = 43) and age-matched healthy volunteers ( = 16) were prospectively enrolled and underwent a 3T CMR exam after obtaining informed consent. Breath-held MRI tagging was used to estimate left ventricular E at the mid-ventricular level as well as the twist, torsion, and θ between basal and apical LV short-axis slices. A two-tailed -test with unequal variance was used to test group-wise differences. Multiple comparisons were performed with Holm-Sidak post hoc correction. Multiple-regression analysis was used to test for correlations among biomarkers. A binomial logistic regression model assessed each biomarker's ability to distinguish the following: (1) healthy volunteers vs. DMD patients, (2) healthy volunteers vs. LGE(-) DMD patients, and (3) LGE(-) DMD patients vs. LGE(+) DMD patients. There was a significant impairment in the peak mid-wall E [-17.0 ± 4.2% vs. -19.5 ± 1.9%, < 7.8 × 10], peak LV twist (10.4 ± 4.3° vs. 15.6 ± 3.1°, < 8.1 × 10), and peak LV torsion (2.03 ± 0.82°/mm vs. 2.8 ± 0.5°/mm, < 2.6 × 10) of LGE(-) DMD patients when compared to healthy volunteers. There was a further significant reduction in the E, twist, torsion, and θ for LGE(+) DMD patients when compared to LGE(-) DMD patients. In the LGE(+) DMD patients, age significantly correlated with LVEF ( = 0.42, = 9 × 10), peak mid-wall E ( = 0.27, = 0.046), peak LV Twist ( = 0.24, = 0.06), peak LV torsion ( = 0.28, = 0.04), and peak LV θ ( = 0.23, = 0.07). In the LGE(-) DMD patients, only the peak mid-wall E was significantly correlated with age ( = 0.25, = 0.006). The peak LV twist outperformed the peak mid-wall LV E and EF in distinguishing DMD patients from healthy volunteer groups (AUC = 0.88, 0.80, and 0.72), as well as in distinguishing LGE(-) DMD patients from healthy volunteers (AUC = 0.83, 0.74, and 0.62). The peak LV twist and peak mid-wall LV E performed similarly in distinguishing the LGE(-) and LGE(+) DMD cohorts (AUC = 0.74, 0.77, and 0.79). The peak mid-wall LV E, peak LV twist, peak LV torsion, and peak LV θ were significantly impaired in advance of the decreased LVEF and the development of focal myocardial fibrosis in boys with DMD and therefore were apparent prior to significant irreversible injury.