Thyroid Function Status and Echocardiographic Abnormalities in Patients with Beta Thalassemia Major in Bahrain

Background: Thyroid gland dysfunction and echocardiographic cardiac abnormalities are well-documented in patients with transfusion dependent beta-thalassemia major (beta-TM). Aim: This cross-sectional analytic study was conducted to investigate left ventricle (LV) diastolic and systolic function using pulsed Doppler (PD) and tissue Doppler (TD) echocardiography and correlate that with serum level thyroid stimulating hormone in patients with beta-TM. Methods: The study was conducted on patients with beta-TM (n = 110, age 15.9 +/- 8.9 years) and compared with a control group (n = 109, age 15.8 +/- 8.9 years). In all participants, echocardiographic indices of PD and TD were performed and blood samples were withdrawn for measuring the serum level of TSH, free T4, and ferritin. A linear regression analysis was performed on TSH level as the dependent variable and serum ferritin as independent. Stepwise multiple regression analysis was used to determine the odds ratio of different biochemical and echo variables on the risk of developing hypothyroidism. Results: Patients with beta-TM compared with controls had thicker LV septal wall index (0.65 +/- 0.26 vs. 0.44 +/- 0.21cm/M-2, P < 0.001), posterior wall index (0.65 +/- 0.23 vs. 0.43 +/- 0.21cm/m(2), P < 0.01) and larger LVEDD index (4.35 +/- 0.69 vs. 3.88 +/- 0.153mm/m(2), P < 0.001). In addition, beta-TM patients had higher transmitral E wave velocity (E) (70.81 +/- 10.13 vs. 57.53 +/- 10.13cm/s, P = 0.02) and E/A ratio (1.54 +/- 0.18 vs. 1.23 +/- 0.17, P < 0.01) and shorter deceleration time (DT) (170.53 +/- 13.3 vs. 210.50 +/- 19.20m sec, P < 0.01). Furthermore, the ratio of transmitral E wave velocity to the tissue Doppler E wave at the basal septal mitral annulus (E/Em) was significantly higher in the beta-TM group (19.68 +/- 2.81 vs. 13.86 +/- 1.41, P < 0.05). The tissue Doppler systolic wave (Sm) velocity and the early diastolic wave (Em) were significantly lower in the beta-TM group compared with controls with Sm, 4.82 +/- 1.2 vs. 6.22 +/- 2.1mm/sec, P < 0.05 and (Em), 3.51 +/- 2.7 vs. 4.12 +/- 2.5mm/sec. P, 0.05, respectively). The tricuspid valve velocity was significantly higher in beta-TM patients compared with controls 2.85 +/- 0.56 vs. 1.743 +/- 0.47 msec, respectively, P < 0.01). The prevalence of subclinical hypothyroidism in patients with beta-TM was 15.4%, with significantly higher mean serum TSH compared with controls (6.78 +/- 1.5 vs. 3.10 +/- 1.02 mu IU/mL, P < 0.01) and positively correlated with the serum ferritin level (r = 0.34, P = 0.014). On multiple regression analysis, the LV mass, LVEF%, and E/A ratio were not positive predictors of hypothyroidism in patients with beta-TM. Conclusion: We conclude that patients with beta-TM had a high prevalence of subclinical hypothyroidism of 15.4%. Thyroid stimulating hormone was significantly high and positively correlated with the serum ferritin level. Echo cardiographic pulsed Doppler showed a restrictive LV diastolic pattern suggestive of severe diastolic dysfunction with preserved left ventricle systolic function.