The impact of overt hypothyroidism on left ventricular mechanical synchrony: speckle tracking echocardiography study

Abstract

Objective To explore the impact of hypothyroidism on left ventricular (LV) mechanics using two-dimensional speckle tracking imaging (2D-STI). Methods Forty-two patients with newly diagnosed overt hypothyroidism (HT) were prospectively collected as the case group and 47 subjects matching by age, gender and hypertension history were enrolled as control group. All participants received comprehensive echocardiography examination, and 2D-STI was used to assess LV global longitudinal strain (GLS) and mechanical dispersion (MD). The inter-group difference in GLS and MD, correlations with thyroid hormones and reproducibility were evaluated. Results LV GLS at both sectional (apical 4-, 3-, 2-chamber views) and global levels were significantly impaired in the HT group than the control group[(-21.3±3.2)% vs (-23.9±2.9)%, (-20.4±3.8)% vs (-22.7±2.9)%, (-21.2±3.9)% vs (-23.9±2.5)%, (-20.9±3.4)% vs (-23.5±2.3)%; all P<0.01]. Similarly, MD at both sectional (apical 4-, 3-, 2-chamber views) and global levels were significantly prolonged in the HT group than the control group[3.4 ms vs 0.9 ms, 2.2 ms vs 0.7 ms, 2.3 ms vs 1.7 ms and 12.2 ms vs (5.9±2.6)ms; all P<0.01]. No significant correlation was found between MD and GLS, left ventricular ejection fraction (LVEF)(r=0.12, P=0.27; r=-0.17, P=0.10). Weak correlations were found between MD and FT3, FT4, TSH(r=-0.34, P=0.01; r=-0.38, P=0.005; r=0.31, P=0.02). Conclusions Primary overt HT is associated with impaired LV deformation and increased systolic dyssynchrony. LV MD is a promising parameter for assessment of myocardial impairment in HT. Key words: Echocardiography; Hypothyroidism; Ventricular function, left; Strain; Mechanical Dispersion; Two-dimensional speckle tracking imaging