Peculiarities of myocardial diastolic function in patients with autoimmune thyroiditis divided according to the mild hypothyroidism range

The aim of the present study was to evaluate myocardial diastolic function in patients with autoimmune thyroiditis (AT) against the TSH level within the reference range and subclinical interval as well as to determine whether it is related to the thyroid function or other metabolic and functional indices. METHODS. We studied diastolic function of left and right ventricles by the ratio of mitral and tricuspid annular early and late diastolic velocities (em/am and et/at respectively) using tissue Doppler imaging; structural heart characteristics by echocardiography; lipid profile and peroxidation parameters; serum ferritin and iron concentrations in 132 middle-aged women. 36 of them were euthyroid controls, 96 had AT and were ranged according to their TSH value into 4 groups: women with “low- normal” (0.4–2.5 mU/L) and “upper-normal” (2.5–4.0 mU/L) TSH range; patients with subclinical hypothyroidism and TSH below and above 6 mU/L. RESULTS. The increase of TSH value within reference range and subclinical interval was associated with the parallel tendency to the em/am and et/at ratio decrease suggesting detrimental effect of the mildest thyroid failure on the left and right ventricles diastolic function. Thus, patients with TSH values >6 mU/L had significantly lower em/am and et/at ratio compared to the “low-normal” TSH group ( p < 0.05) and controls ( p < 0.01). Among them, the highest LDL cholesterol, myocardial mass index and oxidative stress rate were detected as well as lower iron and ferritin serum concentrations ( p < 0.05 compared to controls with regard to all the parameters listed above). Abnormalities in heart structure, lipid and iron metabolism correlated with alterations in ventricular relaxation suggesting that they can contribute, at least partly, to the diastolic dysfunction devel- opment CONCLUSION. The increase of TSH value within reference range and subclinical interval can affect diastolic function of the heart. Its detrimental effect may be mediated, at least partly, by ventricular mass changes, lipid profile and iron metabolism alterations.

diastolic function, autoimmune thyroiditis, TSH within the reference range and subclinical interval

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