Evaluation of ventricular functions using tissue Doppler echocardiography in patients with subclinical hypothyroidism

OBJECTIVES
We evaluated right (RV) and left (LV) ventricle functions by tissue Doppler imaging (TDI) in patients with subclinical hypothyroidism (SH).

STUDY DESIGN
Twenty-seven patients (24 women, 3 men; mean age 35.4±11.4 years) with newly diagnosed SH and 22 age- and sex-matched healthy subjects (20 women, 2 men; mean age 34.8±8.6 years) were evaluated by standard echocardiography and TDI. The diagnosis of SH was based on increased serum thyrotropin (TSH) level in the presence of normal free T3 and free T4 levels. The following TDI-derived parameters were measured: isovolumic myocardial acceleration (IVA), peak myocardial velocity during isovolumic contraction (IVV), peak systolic velocity during ejection period (S), and diastolic indices including peak early (E’) and late (A’) diastolic velocities, E’/A’ and E/E’ ratios, and myocardial performance index.

RESULTS
Compared to healthy controls, patients with SH had higher LV mitral A velocity (p=0.022), lower E/A ratio (p=0.021), lower E’ velocity (p=0.019), and higher E/E’ ratio (p=0.017), suggesting significant LV diastolic dysfunction. The patient group also had lower IVV (p=0.004) and IVA (p<0.001), and higher isovolumic contraction time (p=0.012), suggesting LV subclinical systolic dysfunction. For RV parameters, decreased E/A ratio (p=0.014) and E’ velocity (p=0.028) and increased isovolumic relaxation time (p=0.003) in SH patients were consistent with RV diastolic dysfunction, whereas parameters of RV systolic function were similar in the two groups. Myocardial performance indices of both ventricles were also significantly higher in the patient group (p<0.05).

CONCLUSION
Our data suggest that SH is associated with biventricular systolic and diastolic dysfunction.