QT Dispersion and QTc Interval in Patients with Adult Sickle Cell Disease: Electrocardiographic (EKG) and Echocardiographic Evaluation

Abstract

Background: QT dispersion (QTd) varies according to heterogeneity of recovery time in the myocardium, and the impact of iron overload on the QTd in adult patients with Sickle Cell Disease (SCD) is not clear. Aim: This cross-sectional study was designed to evaluate corrected QTc interval and QTd on 12 leads ECG in patients with SCD, and assess the LV systolic and diastolic function using Pulsed Doppler Echocardiogram. Method: All patients were evaluated clinically with pulse Doppler echocardiography. Twelve leads ECG were taken to measure QTd and QTc. Blood samples withdrawn to assess the blood level of ferritin and hemoglobin. Pearson correlation coefficient was used to measure the linear relationship between serum ferritin and QTd. Results: The study included patients with SCD (n = 70, age 15.7 ± 8.9 years), compared with age-matched healthy control group (n = 70, age 15.9 ± 8.9 years). In patients with SCD compared with healthy control group the QTc (msec) 416 ± 23.21 ms vs. 401 ± 24.12 (p = 0.75), and the QTd were slightly longer in SCD compared with the control of 43 ± 22.1 vs. 38 ± 20.16 msec, (p = 0.071) with no significant difference. M mode echo showed that SCD patients compared with control had higher LVMI gm/M2 of 105 ± 10.3 vs. 83 ± 7.1, P = 0.001, larger LV end diastolic dimension (cm) of 5.5 ± 0.32 vs. 4.72 ± 0.35, p = 0.03, RV diameter (cm) of 2.8 ± 0.42 vs. 2.4 ± 0.31, (p = 0.041) and RV wall thickness (mm) of 0.31 ± 0.06 vs. 0.28 ± 0.03, (p = 0.024). Pulsed Doppler showed high LV transmitral E wave velocity of 85.23 ± 1.92 vs. 62.43 ± 1.67 m/s (p = 0.001), A wave (msec) 46.26 ± 4.7 vs. 56.24 ± 3.2 m/s, p = 0.032, with E/A ratio of 1.86 ± 0.01 vs. 1.10 ± 0.03, (p = 0.024) and DT of E wave (msec) of 156.43 ± 23.5 vs. 189.87 ± 19.5, (p = 0.031). Left ventricle ejection fraction percentage was similar between both groups, but SCD had significantly higher right ventricle tricuspid annular plane systolic excursion TAPSE (cm) of 1.23 ± 0.21 vs. 1.11 ± 0.23 cm (p = 0.02), and the tricuspid valve velocity showed significant higher velocity (m/s) in the SCD patients of 2.9 ± 0.14 vs. 1.7 ± 0.09, p = 0.004 indicating higher pulmonary artery pressure with calculated right ventricle systolic pressure of 38.64 vs. 16.56 mmHg. Conclusion: SCD patients compared with control have higher but not significant QT dispersion and corrected QT interval with a significantly larger LV mass and LV diastolic filling indices suggestive of restrictive diastolic pattern. These data indicate that LV diastolic abnormalities compromised initially in patients with SCD.