Early Cardiac Dysfunction in Pediatric Becker Muscular Dystrophy: A Prospective Cross-sectional Echocardiographic Study

Becker muscular dystrophy (BMD) is an X-linked disorder characterized by progressive muscle weakness and cardiac involvement, with cardiomyopathy being the leading cause of mortality. While cardiac dysfunction in adult BMD patients is well documented, the early cardiac phenotype in pediatric populations remains poorly understood. This prospective cross-sectional study aimed to characterize age-stratified differences in cardiac function among children with BMD, children with Duchenne muscular dystrophy (DMD), and healthy controls. This prospective cross-sectional study included male children aged 3-18 years who were enrolled from June 2020 to December 2023 and met strict inclusion criteria: genetically confirmed BMD or DMD diagnosis, no prior cardiac medications, and absence of comorbid conditions affecting cardiac function. Participants were stratified into three age-matched groups: 3 to under 7 years (youngest group), 7 to under 10 years (middle group), and 10 to under 18 years (oldest group), with comparable mean ages across BMD, DMD, and healthy controls within each age stratum. Comprehensive echocardiographic assessments were performed, including conventional parameters, tissue Doppler imaging, and speckle-tracking echocardiography. Statistical comparisons were made between groups within each age range. The study comprised 86 BMD patients, 86 DMD patients, and 74 controls across three age groups. After normality testing and Bonferroni-corrected post hoc comparisons, BMD patients showed early left ventricular involvement, including lower LVEF (60.54±8.09% vs 65.56±3.04%, p<0.01) and GLS (18.06±2.10 vs 20.66±1.42, p<0.01) than healthy controls from the Younger group onward. Right ventricular enlargement (RV GLS 22.99±3.26 vs 25.58±2.37, p<0.01) and reduced FAC (40.35±6.01% vs 47.8±17.08%, p<0.01) were also evident in BMD, with age-dependent RV strain abnormalities. Compared with DMD, BMD showed larger LVEDV across age groups and relatively preserved GCS, whereas GLS abnormalities (18.06±2.10 vs 20.66±1.42, p<0.01) were still present compared with healthy controls. Left atrial reservoir/conduit indices were better preserved in BMD than DMD in the Older group. In a short-term longitudinal subsample (16 BMD and 19 DMD patients; mean follow-up ∼0.9 years), BMD patients showed a modest decline in LVEF (annualized change 2.01%/year, P = 0.050), while LV-GLS remained stable in both groups. Pediatric BMD patients exhibit subclinical, age-associated cardiac dysfunction detectable across pediatric age groups. Because abnormalities in LVEF, LV GLS, RV FAC, and RV GLS were already present in the youngest group, the findings support early and regular cardiac surveillance incorporating advanced echocardiographic techniques from preschool age. Longitudinal studies are needed to determine whether these subclinical differences predict clinically overt cardiomyopathy or treatment response.