Abstract
Vitamin D deficiency is a recognized complication of β-thalassemia major (β-TM), impacting cardiac function. Speckle tracking echocardiography (STE) offers a sensitive assessment of myocardial deformation, particularly global longitudinal strain (GLS). This study aimed to assess the association between vitamin D levels and LV function in β-TM children and to evaluate the impact of vitamin D supplementation on cardiac parameters. Seventy-five β-TM children underwent vitamin D level assessment, conventional echocardiography, and STE. Patients with vitamin D deficiency/insufficiency (25-OHD3 < 30 ng/ml) received vitamin D supplementation (4000-5000 IU/day). Follow-up assessments were conducted after vitamin D normalization. Vitamin D insufficiency (81.3%) and deficiency (18.7%) were prevalent. Vitamin D levels were inversely correlated with age and disease duration (p < 0.001) and positively correlated with transfusion/chelation therapy onset. Conventional echocardiography showed an inverse correlation between vitamin D level and left ventricular end diastolic diameter (p < 0.001) and deceleration time (p = 0.003). STE revealed a positive correlation between vitamin D and GLS (p < 0.001). Vitamin D supplementation significantly increased median vitamin D levels (from 16.0 to 39.0 ng/ml, p < 0.001) and improved STE parameters, including AP4L, AP3L, AP2L, and GLS (p < 0.001), indicating enhanced myocardial function. CONCLUSION: Vitamin D deficiency in β-TM children was correlated with impaired cardiac function. Vitamin D supplementation significantly improved cardiac function. Regular monitoring and maintenance of adequate vitamin D levels are crucial for preventing adverse cardiac effects. WHAT IS KNOWN: • β-Thalassemia major is frequently complicated by cardiac dysfunction, a major contributor to mortality. • Cardiac iron overload is a primary driver of cardiac dysfunction in β-TM. WHAT IS NEW: • Vitamin D deficiency leads to impaired cardiac function, beyond iron overload, in β-TM children. • Vitamin D supplementation could improve cardiac function in β-thalassemia major patients.