Left ventricular strain and strain rate by two-dimensional speckle tracking echocardiography in patients with subclinical hypothyroidism.

AIM: Subclinical hypothyroidism (SH) is an asymptomatic condition defined by increased serum thyroid-stimulating hormone (TSH) with normal free thyroid hormone levels. Heart is a major target organ for thyroid hormone action. The aim of this study was to evaluate cardiac functions in patients with SH by speckle tracking imaging.

PATIENTS AND METHODS: We included 23 consecutive patients with untreated SH (Group A; 7 male, mean age: 40.9±1.6 years) and 21 patients with treated SH (Group B; 6 male, mean age: 40.2±2.1 years). The control group included 25 healthy volunteers (8 male, mean age: 39.9±2.8 years). Left ventricular (LV) functions were assessed with speckle tracking imaging.

RESULTS: Age and sex distributions were similar among the groups. Mean serum TSH and free T4 levels were 11.7±2.9 µIU/mL, 1.16±0.06 ng/dL for group A; 2.6±0.3 µIU/mL, 1.35±0.09 ng/dL for group B; 1.4±0.3 µIU/mL, 1.31±0.09 ng/dL for controls, respectively (p = 0.001, p = 0.122). The untreated SH patients had significantly lower LV strain and strain rate values compared to controls. The treated SH patients had higher LV strain and strain rate values compared to untreated SH patients although the difference was not statistically significant. The treated SH patients had lower LV strain and strain rate values compared to controls but the difference was not statistically significant.

CONCLUSIONS: Untreated SH is associated with impairment in LV longitudinal myocardial function. Speckle tracking echocardiography appears to be useful both for early detection of LV impairment in patients with SH and documentation of improvement in myocardial deformation parameters with treatment.