Abstract
Prognosis of Duchenne muscular dystrophy (DMD) is related to cardiac dysfunction. Two dimensional-speckle tracking echocardiography (2D-STE) has recently emerged as a non-invasive functional biomarker for early detection of DMD-related cardiomyopathy. This study aimed to determine, in DMD children, the existence of a left ventricle (LV) dyssynchrony using 2D-STE analysis. This prospective controlled study enrolled 25 boys with DMD (mean age 11.0 ± 3.5 years) with normal LV ejection fraction and 50 age-matched controls. Three measures were performed to assess LV mechanical dyssynchrony: the opposing-wall delays (longitudinal and radial analyses), the modified Yu index, and the time-to-peak delays of each segment. Feasibility and reproducibility of 2D-STE dyssynchrony were evaluated. All three mechanical dyssynchrony criteria were significantly higher in the DMD group than in healthy subjects: – opposing-wall delays in basal inferoseptal to basal anterolateral segments (61.4 ± 45.3 msec vs. 18.3 ± 50.4 msec, P < 0.001, respectively) and in mid inferoseptal to mid anterolateral segments (58.6 ± 35.3 msec vs. 42.4 ± 36.4 msec, P < 0.05, respectively); – modified Yu index (33.3 ± 10.1 msec vs. 28.5 ± 8.1 msec, P < 0.05, respectively); – most of time-to-peak values, especially in basal and mid anterolateral segments. Feasibility was excellent and reliability was moderate to excellent, with ICC values ranging from 0.49 to 0.97 ( Fig. 1 ). Detection of LV mechanical dyssynchrony using 2D-STE analysis is an easily and reproducible method in pediatrics. The existence of an early LV mechanical dyssynchrony visualized using 2D-STE analysis in children with DMD before the onset of cardiomyopathy represents a perspective for future pediatric drug trials in the DMD-related cardiomyopathy prevention.
Highlights
Duchenne muscular dystrophy (DMD) is an X-linked recessive myopathy leading to loss of dystrophin, a constitutive protein of muscle architecture
The existence of an early left ventricle (LV) mechanical dyssynchrony visualized using 2D-STE analysis in children with DMD before the onset of cardiomyopathy represents a perspective for future pediatric drug trials in the DMD-related cardiomyopathy prevention
In accordance with recommendations published in Shrout and Fleiss [31], we evaluated the reproducibility of the performed measurements by calculating intraclass correlation coefficients (ICC) of type (2,1) for interobserver and intraobserver reliability, as only one investigator was responsible for the double analysis to assess intraobserver reliability, and a single pair of investigators produced the two analyses to assess interobserver reliability
Summary
Duchenne muscular dystrophy (DMD) is an X-linked recessive myopathy leading to loss of dystrophin, a constitutive protein of muscle architecture. Heart failure due to progressive dilated cardiomyopathy usually occurs at the end of adolescence, and represents the main cause of death in this population [2]. Clinical presentation of DMD-related cardiomyopathy is often misleading, with poor symptomatology, less marked left ventricle (LV) dilatation, and worse prognosis than other etiologies of heart failure [3, 4]. Cardiac screening is usually based on noninvasive echocardiography standard parameters, such as left ventricle ejection fraction (LVEF) and LV diameter, which are reliable and reproducible measures in pediatrics. Alteration of those parameters appears at a late stage in DMDrelated cardiomyopathy natural history. From a prospective controlled study, we recently reported the existence of 2D-STE anomalies in children with DMD, before the onset of cardiomyopathy, especially in the longitudinal strain of basal inferolateral and anterolateral segments [6]
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