Endocrine Abstracts

Introduction and aims: Autoimmune thyroiditis represent a state predisposed for the development of hypothyroidism. It is known that subclinical and overt hypothyroidism are important risk factors associated with the development and progression of heart failure. These effects are due to the changes in the structure and function of the cardiac muscle, as well as the overall cardiac mechanics. The aim of our study was to examine the influence of autoimmune thyroiditis (Hashimoto thyroiditis-HT) on the risk of developing a heart failure.

Methods: We analyzed 56 patients with HT, thereof 31 patients were considered sub-/clinically hypothyroid and on substitution therapy with l-thyroxine. Control group consisted of 25 sex-, age- and BMI- matched healthy individuals. We determined values of thyroid hormones (triiodothyronine T3 and thyroxine T4) and thyroid antibodies (anti-TPO and anti-Tg), as well as serum lipid levels [cholesterol, HDL, LDL and triglycerides (Tg)]. Ultrasonographic evaluation of cardiac cavities [left atrium (LA) area, LA volume, right ventricle (RV), end systolic diameter left ventricle (ESDLV), end diastolic diameter left ventricle (EDDLV), heart wall thickness (posterior left ventricle wall -PLVW, interventricular septum- IVS, systolic function (ejection fraction-EF), diastolic function (E/A) and decelerating time (DT) were evaluated. Statistical analysis was done using the SPSS software.

Results: Patients with HT had significantly higher values of TSH (P=0.002), cholesterol (P=0.02) and LDL (P=0.009). They also had significantly higher parameters of the size of the LA (P=0.005 for LP area, P=0.03 for LP vol) and DT (P=0.007), while the values of other cardiac parameters did not differ significantly among groups (P> 0.05 for all). Thyroid hormone and antibody values were not correlated with echocardiographic parameters in patient with HT (P> 0.05), except that T3 levels significantly correlated with DT (P=0.031). A significant correlation was confirmed between the values of cholesterol and RV (P=0.041), IVS (P=0.041), IVS (P=0.16), ESDLV (P=0.005), LAarea (P=0.025) and LAvol (P=0.013) in patients with HT. Also, the value of Tg was significantly correlated with RV (P=0.005), LAarea (P=0.002) and LAvol (P=0.008), and LDL with PLVW (P=0.047) and ESDLV (P=0.018). In patient with previous hypothyroidism duration of treatment was significantly correlated with IVS (P=0.05), LAarea (P=0.003) and LAvol (P=0.011) and the dose of l-thyroxine with IVS (0.039), ESDLV (P=0.002), LAarea (P=0.013) and LAvol (P=0.028).

Conclusion: Overt hypothyroidism leads to structural changes of the myocardium, which is only partially reversible after adequate substitution, indicating the need for timely diagnosis of hypothyroidism in patients with autoimmune thyroiditis.