Influence of the Subclinical Hypothyroidism on the Left Ventricular Systolic and Diastolic Function (pilot study)

Abstract

Introduction: The clinically manifested hypothyroidism is associated with systolic and diastolic dysfunction. Studies investigating the left ventricular function in subclinical hypothyroidism (ScH) have shown controversial results. The aim of the study was to assess whether ScH is associated with the left ventricular systolic and diastolic dysfunction. Material and methods: Seventeen consecutive patients with newly diagnosed ScH and 20 healthy euthyroid patients as controls were analyzed. The two groups were appropriate by: age, sex, and body mass index. Laboratory analyses were performed in all patients - determination of TSH, free thyroxin (FT4), free triijodothyronine (FT3), antibodies directed to thyroid peroxidase (TPOAb) and antitiroglobulin antibodies (TgAb), and the assessment of left ventricular systolic and diastolic function by M-mode, two-dimensional echocardiography, pulse, continuous and color-Doppler, advanced echocardiographic modalities Tissue Doppler (TDI) and two-dimensional speckle tracking. Results: ScH patients had statistically significant lower ejection fraction, smaller ratio s/d (where s is the systolic velocity and d is the diastolic velocity through the pulmonary veins) and lower negative longitudinal global strain compared with the control group (62.1 ± 2.1 vs. 58.7 ± 6.2%, p<0.05, 1.27 ± 0.12 vs. 1.06 ± 0.20, p<0.001, -0.21 ± 0.01 versus -0.19 ± 0.01%, p<0.05, respectively). There was a statistically significant negative correlation of TSH with s/d and S/ TDI (r = 0.43 and r = 0.26, p<0.05, respectively). There was a statistically significant negative correlation of free thyroxine with myocardial performance index (r = -0.17, p<0.05), and a positive correlatin with s/d (r =0.48, p<0.05). Conclusion: ScH was associated with a statistically significant reduction in global systolic and global longitudinal systolic function of the left ventricle.