Evaluation of left atrial mechanical functions and atrial conduction abnormalities in patients with clinical hypothyroid.

Background: The aim of this study was to investigate left atrial (LA) mechanical functions, atrial electromechanical delay and P wave dispersion in hypothyroid patients.

Methods: Thirty-four patients with overt hypothyroid and thirty controls were included. A diagnosis of overt hypothyroid was reached with increased serum TSH and decreased free T4 (fT4) levels. LA volumes were measured using the biplane area length method and LA active and passive emptying volumes and fraction were calculated. Intra- and interatrial electromechanical delay (EMD) were measured by tissue Doppler imaging (TDI). P wave dispersion was calculated by 12 lead electrocardiograms.

Results: LA diameter were significantly higher in patients with overt hypothyroid (p = 0.021). LA passive emptying volume and LA passive emptying fraction were significantly decreased with hypothyroid patients (p = 0.002 and p < 0.001). LA active emptying volume and LA active emptying fraction were significantly increased with hypothyroid patients (p < 0.001 and p < 0.001). Intra- and interatrial EMD, were measured significantly higher in hypothyroid patients (30.6 ± 6.1 vs 18.0 ± 2.7, p< 0.001; and 10.6 ± 3.4 vs 6.9 ± 1.4, p < 0.001, respectively). P wave dispersion were significantly higher in hypothyroid patients (48.8 ± 6.2 vs 44.3 ± 7.2, p = 0.022). In stepwise regression analysis demonstrated that, interatrial EMD and LA active emptying fraction related with TSH and fT4.

Conclusions: This study showed that impaired LA mechanical and electromechanical function in hypothyroid patients. TSH and T4 were independent determinant of interatrial EMD and LA active emptying fraction.