Thyroid hormone levels and echocardiographic changes in subclinical hypothyroidism: a correlation study

Objective Overt hypothyroidism has been linked to alterations in cardiac output and diastolic dysfunction. Moreover, subclinical hypothyroidism (SCH) exhibits changes in echocardiographic parameters when compared to healthy individuals. This study investigates the correlation between thyroid hormone values and echocardiographic parameters in patients diagnosed with SCH. Methods In fifty-four patients with newly diagnosed ScH who met the criteria for levothyroxine treatment, blood tests and echocardiographic studies were conducted at enrollment and again after five months of maintaining a euthyroid state. Results TSH negatively correlated with EF, E/A, GLS, S/TDI (r=-0.15, r=-0.14, r=-0.26, r=-0.22, P<0.05, respectively), and positively correlated with E/e ’sep. (r= 0.14, P <0.05). FT4 negatively correlated with F/f’sep., IVRT, MPI (r=-0.17, r=-0.21, r=-0.19, P <0.05, respectively), and positively correlated with F/A, GLS, S/TDI (r = 0.18, r=-0.18, r=0.19, P < 0.05, respectively). FT3 negatively correlated with A dur (r=-0.39, P < 0.01), and positively correlated with EF and s/d (r=0.18, r=0.22, P<0.05). Using a general linear model with univariate analysis, we found that TSH had a statistically significant independent influence on EF, LVEDd, IVRT, MPI, GLS, and S/TDI. FT4 significantly influenced EF, LVEDd, LVEDvol, E/A, A dur, Ar dur, MPI, GLS, s/d, and S/TDI, while FT3 had a significant impact on EF, LVEDd, IVCT, MPI, and GLS (P <0.05). After substitution therapy, there was a statistically significant improvement in parameters indicating diastolic dysfunction (A dur: 112.18G17.2 vs. 107.25G 14.4 msec and E/e’ sep.: 7.62G2.29 vs. 6.60G2.06, P ! 0.01), as well as in global and longitudinal left ventricular function (MPI: 0.47G0.08 vs. 0.43G0.07 and GLS: -19.55G2.3 vs. -20.07G2.7, P ! 0.05). Conclusion Thyroid hormones directly influence specific parameters used to assess global and longitudinal systolic and diastolic left ventricular function in patients with ScH, and the most of them are reversible with levothyroxine treatment. Keywords subclinical hypothyroidism, echocardiography, left ventricular function.