The role of echocardiography in monitoring the therapeutic effect of levothyroxine replacement therapy in subclinical hypothyroidism

Abstract

Current controversies related to the treatment of subclinical hypothyroidism (SCH) with thyrotropin (TSH) < than 10 mU/L are based on the lack of evidence that levothyroxine therapy has beneficial effects. The aim of our study is to estimate the effect of levothyroxine treatment on cardiac morphology and function in subclinical hypothyroidism. Body mass index, waist circumference, blood pressure, electrocardiographic and standard echocardiographic parameters were measured before levothyroxine therapy and 3 months after TSH normalization. Significant reduction in systolic and diastolic blood pressure, PR, QT and QT corrected intervals, as well as increase in heart rate were recorded in the group on levothyroxine therapy. The following parameters of the left and right ventricle were significantly decreased in the treatment group: left ventricular mass index and volume, systolic and diastolic time intervals, and mitral annular plane systolic excursion (MAPSE). The increase was recorded as fractional shortening and pressure rise in early systole (dP/dt), right atrial wall thickness and diameters. Our study did not confirm differences in basic echocardiographic parameters between the treated and control groups, apart from an echocardiographic improvement of cardiac structure and function in treated individuals. The findings suggest electrocardiographic and echocardiographic screening in monitoring the therapeutic effect.

Calculation of left ventricular volumes and systolic indices in monitoring the therapeutic effect of levothyroxine replacement therapy in subclinical hypothyroidism

“…The insufficiency of thyroid hormones may cause a prolongation of the QT interval and predisposition to ventricular irritability. 20,27,28 Observed prolongation of the QT interval in our patients was reversible on LT4 treatment, as it was previously noted. 20,28 Thyroid hormones deficiency also leads to increased venous resistance and diastolic hypertension.…”

“…Treatment outcome in patients with subclinical hypothyroidism; endsystolic volume (mean ± SD ESV) before and after levothyroxine therapy indicates that the improvement of cardiac contractility should not be attributed to heart rate increase per se. 20 Also, there was no significant correlation between heart rate change and cardiac contractility and myocardial deformation strain measures changes, which support the influence of thyroxine replacement as a predominant cause of their improvements.…”

“…Additional data, especially related to the ECG parameters, are presented elsewhere. 20 In order to eliminate a potential effect of heart rate improvement on cardiac contractility and myocardial strain measures changes, we correlated heart rate change with dP/dt and strain values (GLS, GCS, GRS). There were no statistically significant correlations among those changes (r = −0.207, P = .233; r = −0.217, P = .210; r = 0.230, P = .184; r = −0,153, P = .379; respectively).…”

Correlation between echocardiographic findings and biochemical markers in term newborns with moderate to severe perinatal asphyxia

“…We found that a mild negative correlation existed between troponins and FS in all patients, while a significant negative correlation between serum cTnI and FS among asphyxiated neonates was previously described [19]. Some studies showed that cTnT levels correlated with echocardiographic findings of myocardial dysfunction, meaning it correlated positively with the left and right ventricle Tei index, stroke volume and left ventricular output, and negatively with mitral and tricuspid systolic velocity [19,20].…”

Thyroid replacement therapy effects on cardiac function in patients with hypothyroidism

“…There is a milder degree of left ventricular hypertrophy in the overt hypothyroidism with an increase in posterior wall thickness more than the interventricular septum, suggesting that concentric remodeling of the left ventricle is developed during thyroid dysfunction, which is reversible by L-thyroxine administration [15,16]. The LVEF is usually normal or slightly reduced in thyroid dysfunction, with a slight increase during therapy, mainly during exercise and less at rest [17].…”