The Correlation Between Myocardial Dysfunction and Age in Duchenne Muscular Dystrophy: Assessed by Cardiac Magnetic Resonance Tissue Tracking

Backgro und: Duchenne muscular dystrophy (DMD) is a progressive disorder affecting skeletal muscles, the heart, the respiratory system, and the nervous system, with cardiovascular complications emerging as the primary cause of mortality in DMD patients. Objectives: This study aims to quantitatively assess myocardial strain in patients with DMD using cardiac magnetic resonance (CMR) tissue tracking technology. The study seeks to evaluate subclinical cardiac dysfunction and investigate variations in myocardial dysfunction across different age groups. Additionally, it aims to explore the correlation between myocardial strain parameters and myocardial fibrosis. Methods : Between August 2018 and January 2020, 110 DMD patients diagnosed at a pediatric neurology outpatient department were included in the study. The patients were categorized into three age groups: 1-6 years, 7-10 years, and 11-14 years. Based on left ventricular ejection fraction (LVEF), the patients were further divided into a normal LVEF group (LVEF ≥ 55%) and a decreased LVEF group (LVEF < 55%). Furthermore, based on the presence of delayed enhancement, patients were classified into late gadolinium enhancement (LGE) positive and LGE negative groups. Additionally, 69 healthy volunteers were recruited for comparison. In conclusion, parameters of left ventricular (LV) function, along with global and local myocardial strain parameters of the left ventricle, were assessed. These included radial, circumferential, and longitudinal peak strains at the base, middle, and apex of the left ventricle. Statistical analyses were conducted using the T-test. Results: In comparison to the control group (n = 21), the cardiac function and myocardial strain of patients aged 3-6 years (n = 15) did not exhibit any decline. LVEF (59.58 ± 7.09 vs 63.39 ± 5.27), left ventricular global radial (37.34 ± 9.78 vs 42.95 ± 9.22), circumferential (- 20.75 ± 3.77 vs -22.09 ± 2.46) and longitudinal (- 13.91 ± 2.81 vs -15.69 ± 2.52) strain and local strain parameters of DMD patients (n = 63) at the age of 7-10 years were lower than that of normal volunteers(n = 18) . With the increase of age, compared with normal volunteers(n = 22), patients with DMD at the age of 11-14 years old(n = 21) further expanded the range of local strain reduction in the left ventricle than those in the age group of 7-10 years, except for the reduction of LVEF (59.61 ± 9.27 vs 62.22 ± 3.93), left ventricular global radial (36.48 ± 10.22 vs 41.82 ± 8.38), circumferential (- 19.49 ± 4.13 vs -21.97 ± 2.37) and longitudinal (- 12.59 ± 2.38 vs -14.51 ± 2.16) were all decreased. The number of the decreased local strain parameters were more than 7-10 years patients. For patients in LVEF preserved group(n = 77), even if there was no significant difference in cardiac function between LVEF preserved group and normal control group (61.37 ± 6.06 vs 62.74 ± 4.48), the global and local myocardial strain of left ventricle had decreased in different degree. LGE negative patients (n = 51)showed a decrease in global and local myocardial strain without a decrease in cardiac function (60.89 ± 6.42 vs 62.74 ± 4.48). Conclusions: In patients with DMD, myocardial dysfunction predominantly manifests in children older than seven years, exhibiting a subtle progression that exacerbates with advancing age. The myocardial injury tends to develop from the basal epicardium towards the apical and endocardial regions. CMR tissue tracking offers an earlier assessment of cardiac dysfunction in DMD patients compared to traditional parameters such as LVEF and LGE.