Impairment of Left Ventricular Function in Hyperthyroidism Caused by Graves' Disease: An Echocardiographic Study

The thyroid gland has an important influence on the heart. Long-term exposure to high levels of thyroid hormones may lead to cardiac hypertrophy and dysfunction. The aim of the study was to evaluate the morphological and functional changes in the left ventricle in patients with hyperthyroidism caused by Graves' disease (GD) in comparison with healthy individuals, as well as to investigate potential differences in these parameters in GD patients in relation to the presence of orbitopathy. The prospective study included 39 patients with clinical manifestations and laboratory confirmation of GD and 35 healthy controls. All participants underwent a detailed echocardiographic examination. The groups were compared according to demographic characteristics (age and gender), heart rate and echocardiographic characteristics. The patients with hyperthyroidism caused by GD had significantly higher values of left ventricular diameter, left ventricular volume and left ventricular mass compared to the healthy controls. In addition, hyperthyroidism significantly influenced the left ventricular contractility and led to the deterioration of the systolic and diastolic function, as shown together by longitudinal strain, color Doppler and tissue Doppler imaging. However, the patients with GD and orbitopathy showed better left ventricular function than those without orbitopathy. Besides the confirmation of previously known findings, our study indicates possible differences in echocardiographic parameters in GD patients in relation to the presence of orbitopathy. Further investigation with larger samples and meta-analyses of data focused on the evaluation of echocardiographic findings in the context of detailed biochemical and molecular analyses is required to confirm our preliminary results and their clinical significance.