Thyroid replacement therapy effects on cardiac function in patients with hypothyroidism

Abstract

Introduction/Objective. Hypothyroidism is a hypometabolic syndrome with insufficient production or inadequate action of thyroid hormones. It is characterized by hypercholesterolemia, elevated LDL-C. The most common echocardiographic changes are in left ventricular (LV) diastolic function. The aim of this study was to investigate the effects of achieving adequate thyroid hormone replacement therapy in hypothyroid patients on improving systolic and diastolic cardiac function and correcting serum lipid profile. Methods. Prospective study was conducted on 42 patients with newly diagnosed hypothyroidism, both sexes, aged 18?60 years, without comorbidity. The determined blood tests before, six, 12, and 24 weeks after starting the therapy with L-thyroxine were: FT4, TSH, total cholesterol, HDL-C, LDL-C and triglycerides. The effects of thyroid hormone replacement therapy on systolic and diastolic cardiac function were assessed by echocardiography. Results. It was concluded that 25 (59.5%) patients had subclinical and 17 (40.5%) overt hypothyroidism. The LV end-systolic diameter decreased statistically highly significant (p < 0.01) after 12 weeks and enddiastolic diameter of the right ventricle after six months of therapy. There was no significant decrease in LV end-diastolic diameter after six months of thyroid hormone replacement therapy. Mitral annular plane systolic excursion (MAPSE), left ventricular ejection fraction (LVEF), and tricuspid annular plane systolic excursion (TAPSE) values increased significantly (p < 0.01) after six weeks of therapy. Total cholesterol and LDL-C significantly decreased, HDL-C increased (p < 0.01) and there was no change in triglyceride concentrations after 24 weeks of therapy. Conclusions. Thyroid replacement therapy in hypothyroid subjects statistically significantly improves echocardiographic parameters of diastolic and systolic left and right ventricular function, reduces total serum cholesterol and LDL-C, and increases HDL-C.