Evaluation of left ventricular diastolic function using tissue Doppler echocardiography and conventional doppler echocardiography in patients with subclinical hypothyroidism aged <60 years: a meta-analysis.

Studies have suggested that subclinical hypothyroidism (SCH) may have detrimental effects on left ventricular (LV) diastolic function. Whether SCH is a risk factor for LV diastolic dysfunction is controversial. Databases (MEDLINE, PubMed, EMBASE) were searched for cross-sectional studies evaluating LV diastolic function in SCH patients aged <60 years using tissue Doppler echocardiography (TDE) and conventional two-dimensional Doppler echocardiography (2D-DECG) published in the past 12 years. The weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using fixed or random-effects models. We summarized the results of 14 cross-sectional studies with 675 participants. SCH patients had a significantly lower LV mitral annular E(a) peak velocity (WMD=-1.71 cm/s; 95%CI: -3.02 to -0.40; p<0.05), E(a)/A(a) ratio (WMD=-0.22; 95%CI: -0.40 to -0.05; p<0.05), and significantly higher mitral annular A(a) peak velocity (WMD=0.47 cm/s; 95%CI: 0.10-0.85; p<0.05) than euthyroid subjects using TDE. Subgroup analyses showed that statistical significance existed only in E(a) and E(a)/A(a) parameters when data from "women ≥ 90%" were used, and in the A(a) parameter when data from "women<90%" were used. No matter which subgroup of females was used, there were significant differences in LV peak transmitral A velocity (WMD=7.64 cm/s; 95%CI: 4.55-10.73; p<0.05), and E/A ratio (WMD=-0.22; 95%CI: -0.31 to -0.21; p<0.05) but no significant difference in peak transmitral E velocity (p>0.05) between SCH patients and euthyroid controls using 2D-DECG. Therefore, for those aged <60 years, SCH patients had significantly worse parameters of LV diastolic function than euthyroid controls.