Effect of Average Annual Mean Serum Ferritin Levels on QTc Interval and QTc Dispersion in Beta-Thalassemia Major

Abstract

Background There is evidence indicating impaired cardiomyocytic contractility, delayed electrical conduction and increased electrophysiological heterogeneities due to iron toxicity in beta-thalassemia major patients. In the present study, we compared the electrocardiographic and echocardiographic features of beta-thalassemia major patients with a healthy control group. Materials and Methods The average annual serum ferritin levels of fifty beta-thalassemia major patients were assessed. For each patient, corrected QT (QTc) intervals and QTc dispersions (QTcd) were calculated and V1S and V5R were measured. All subjects underwent two-dimensional M-mode echocardiography and Doppler study and were compared with 50 healthy subjects as a control group. Results QTc interval and dispersion were significantly higher in beta-thalassemia major patients (P= 0.001). The mean V5R (20.04 ± 4.34 vs. 17.14 ± 2.55 mm) and V1S (10.24 ± 2.62 vs. 7.83 ± 0.38 mm) showed considerably higher mean values in patients in comparison with control group.Peak mitral inflow velocity at early diastole and early to late ratio in the case- group was markedly higher(P<0.001), whereas, early deceleration time (P=0.01) and Isovolumic relaxation time (IVRT) (P=0.001), were meaningfully lower than the control group. There was positive correlation between age and QTc (r= 0.831, P=0.001) and QTc dispersion (r= 0.710, P=0.001) and negative correlation between serum level of ferritin and V5R (r= -0.271, P= 0.05). Conclusion Measurement of the QTc interval and dispersion can be used for early detection of cardiac involvement, especially in asymptomatic beta-thalassemia patients with ferritin levels higher than 2,500 ng/dl.