Subclinical cardiovascular involvement in pediatric euthyroid Hashimoto's thyroiditis: the hidden burden of autoimmunity.

UNLABELLED: Hashimoto's thyroiditis (HT) is an autoimmune disorder that may influence cardiovascular health, even in euthyroid states. This study aimed to evaluate early cardiac and vascular changes in pediatric patients with euthyroid HT using advanced echocardiographic techniques. Thirty euthyroid female adolescents with newly diagnosed, untreated HT and 36 age-matched healthy controls underwent conventional and tissue Doppler echocardiography. Myocardial performance index (MPI), isovolumic contraction time (IVCT), and isovolumic relaxation time (IVRT) were measured. Aortic elasticity parameters including aortic stiffness index (ASI), strain, and distensibility were also evaluated. Compared to controls, the HT group showed significantly prolonged IVCT and IVRT and elevated MPI values, suggesting subclinical left ventricular dysfunction (p < 0.01). While standard M-mode measures were similar between groups, tissue Doppler detected subtle myocardial impairments. ASI was significantly increased in the HT group (p = 0.025), despite no differences in lipid or hs-CRP levels. Positive correlations were observed between anti-TPO and anti-Tg antibody levels and myocardial function indices.

CONCLUSION

Pediatric patients with euthyroid HT may exhibit early subclinical myocardial and vascular abnormalities. These findings emphasize the importance of early cardiovascular evaluation in this population, regardless of thyroid hormone levels, and support the role of autoimmunity in cardiac involvement.

WHAT IS KNOWN: • Hashimoto's thyroiditis is the most prevalent autoimmune thyroid disorder characterized by the presence of thyroid autoantibodies, including anti-TPO and anti-Tg. Patients with Hashimoto's thyroiditis may present in hypothyroid, hyperthyroid, or euthyroid states, and the cardiovascular implications of overt thyroid hormone abnormalities are well established. • Prior studies have established that thyroid hormones exert effects on cardiac function through genomic and nongenomic pathways. Nevertheless, the role of autoimmune processes in contributing to subclinical cardiovascular changes, even in patients who present with normal thyroid hormone levels, has garnered increasing attention in recent literature.

WHAT IS NEW: • In Hashimoto's thyroiditis, alterations in the cardiovascular system occur independently of thyroid hormone levels. Our findings suggest that subclinical myocardial dysfunction and increased arterial stiffness may manifest early in the disease progression, with a positive correlation observed between thyroid autoantibodies and markers indicative of cardiac dysfunction. • The correlation analysis demonstrated significant positive associations between thyroid autoantibody levels (anti-TPO and anti-Tg) and indices of myocardial performance, suggesting that a greater autoimmune burden might directly impact cardiac function.