The effect of levothyroxine treatment on left ventricular function in subclinical hypothyroidism

Abstract

Objective: Treatment of subclinical hypothyroidism (ScH), especially the mild form of ScH, is controversial because thyroid hormones influence cardiac function. We investigate left ventricular systolic and diastolic function in ScH and evaluate the effect of 5-month levothyroxine treatment. Subjects and methods: Fifty-four patients with newly diagnosed mild ScH (4.2 < TSH < 10.0 mU/L) and 30 euthyroid subjects matched by age were analysed. Laboratory analyses and an echocardiography study were done at the first visit and after 5 months in euthyroid stage in patients with ScH. Results: Compared to healthy controls, patients with ScH had a lower E/A ratio (1.03 ± 0.29 vs. 1.26 ± 0.36, p < 0.01), higher E/e' sep. ratio (7.62 ± 2.29 vs. 6.04 ± 1.64, p < 0.01), higher myocardial performance index (MPI) (0.47 ± 0.08 vs. 0.43 ± 0.07, p < 0.05), lower global longitudinal strain (GLS) (-19.5 ± 2.3 vs.-20.9 ± 1.7%, p < 0.05), and lower S wave derived by tissue Doppler imaging (0.077 ± 0.013 vs. 0.092 ± 0.011 m/s, p < 0.01). Levothyroxine treatment in patients with ScH contributed to higher EF (62.9 ± 3.9 vs. 61.6 ± 4.4%, p < 0.05), lower E/e' sep. ratio (6.60 ± 2.06 vs. 7.62 ± 2.29, p < 0.01), lower MPI (0.43 ± 0.07 vs. 0.47 ± 0.08%, p < 0.01), and improved GLS (-20.07 ± 2.7 vs.-19.55 ± 2.3%, p < 0.05) compared to values in ScH patients at baseline. Furthermore, in all study populations (ScH patients before and after levothyroxine therapy and controls), TSH levels significantly negatively correlated with EF (r =-0.15, p < 0.05), E/A (r =-0.14, p < 0.05), GLS (r =-0.26, p < 0.001), and S/TDI (r =-0.22, p < 0.01) and positively correlated with E/e' sep. (r = 0.14, p < 0.05). Conclusion: Patients with subclinical hypothyroidism versus healthy individuals had subtle changes in certain parameters that indicate involvement of systolic and diastolic function of the left ventricle. Although the values of the parameters were in normal range, they were significantly different compared to ScH and the control group at baseline, as well as to the ScH groups before and after treatment. The results of our study suggest that patients with ScH must be followed up during treatment to assess improvement of the disease. Some of the echocardiography obtained parameters were reversible after levothyroxine therapy.

Early L-T4 intervention improves fetal heart development in pregnant rats with subclinical hypothyroidism rats by activating BMP4/Smad4 signaling pathway

“…It was reported that compared with healthy people, the left ventricular systolic and diastolic function of SCH patients was slightly affected. Moreover, L-T4 treatment reversed the change of left ventricular systolic and diastolic function of SCH patients, but has no significant effect on systolic pressure [11]. A similar study also found that for children with hypothyroidism and ventricular diastolic dysfunction, L-T4 treatment can significantly improve left ventricular dysfunction [12].…”

Early L-T4 intervention improves fetal heart development in pregnant rats with subclinical hypothyroidism rats by activating BMP4/Smad4 signaling pathway

“…It was reported that compared with healthy people, the left ventricular systolic and diastolic function of SCH patients was slightly affected. Moreover, L-T4 treatment reversed the change of left ventricular systolic and diastolic function of SCH patients, but has no signi cant effect on systolic pressure [11]. A similar study also found that for children with hypothyroidism and ventricular diastolic dysfunction, L-T4 treatment can signi cantly improve left ventricular dysfunction [12].…”

Thyroid gland dysfunction and its effect on the cardiovascular system: a comprehensive review of the literature

“…Ozturk S. et al performed echocardiography in ScH patients and, using tissue Doppler imaging (TDI), measured the maximal systolic velocity of the mitral valve ring motion (S'), which is a parameter of LV systolic function. They showed a statistically significant reduction of S' in patients with ScH compared to the controlled group; however, levothyroxine treatment did not improve the S' [66].…”

“…Myocardial performance index (MPI), a parameter measuring global LV systolic function, is generally shown to be abnormal in ScH patients. MPI values can be reversed with levothyroxine treatment [66,67]. Global longitudinal strain (GLS) is a better parameter for measuring LV global systolic function, mainly when the ejection fraction (EF) is normal.…”