QTc Interval and QT Dispersion in Patients with Thalassemia Major: Electrocardiographic (EKG) and Echocardiographic Evaluation

BACKGROUND Doppler echocardiographic studies in patients with beta-Thalassemia Major (beta-TM) had shown different patterns of left ventricle (LV) systolic and diastolic dysfunctions. AIM This cross-sectional study was designed to study the LV systolic and diastolic function in patients with beta-TM using Pulsed Doppler (PD) Echocardiogram and assess the QTc interval and QT dispersion (QTd) on 12 leads ECG. METHOD All patients were evaluated clinically as well as by echocardiography and 12 leads ECG. The study included patients with beta-TM (n = 38, age 15.7 +/- 8.9 years), compared with an age-matched healthy control group (n = 38, age 15.9 +/- 8.9 years). RESULTS In 38 patients with beta-TM Compared with healthy control group, The QTc interval and the QTd dispersion on ECG were increased with no significant difference mode echo showed that beta-TM patients have thicker LV septal wall index (0.659 +/- 0.23 vs. 0.446 +/- 0.219 cm/M(2), P < 0.001), posterior wall index (0.659 +/- 0.235 vs. 0.437 +/- 0.214 cm/M(2), P < 0.01), and larger LVEDD index is (3.99 +/- 0.48 vs. 2.170 +/- 0.57 cm/M(2). P < 0.05). Pulsed Doppler showed high LV trans-mitral E wave velocity index (70.818 +/- 10.139 vs. 57.532 +/- 10.139, P < 0.05) and E/A ratio (1.54 vs.1.23, P < 0.01). The duration of deceleration time index (DT) and isovolumic relaxation time index (IVRT) were significantly shorter in patients with beta-TM (150.234 +/- 20.0.23 vs. 167.123 +/- 167.123 +/- 19.143 msec/M(2), P < 0.01) and (60.647 +/- 6.77 vs. 75.474 +/- 5.83 msec/M(2), P < 0.001), respectively. The tricuspid valve velocity in patients with beta-TM was significantly higher than controls (2.993 +/- 0.569 vs. 1.93 +/- 0.471 m/sec, respectively, P < 0.01), with calculated pulmonary artery pressure of 2.4 times the control (36.0 vs. 14.8 mmHg). However, the LVEF% or fractional shortening were not significantly different. CONCLUSION In this study, beta-thalassemia major patients compared with controls have differences of QT dispersion and corrected QT interval that is of no statistical significance. A significantly thicker LV wall and LV diastolic filling indices are suggestive of restrictive diastolic pattern. These data indicate that LV diastolic abnormalities compromised initially in patients with beta-thalassemia major.