Dispersion of repolarization and beta‐thalassemia major: the prognostic role of QT and JT dispersion for identifying the high‐risk patients for sudden death

V Russo, A Rago, B Pannone, AA Papa… - European Journal of …, 2011 - Wiley Online Library
V Russo, A Rago, B Pannone, AA Papa, F Di Meo, MC Mayer, A Spasiano, MG Russo…
European Journal of Haematology, 2011Wiley Online Library
Background: Patients with beta‐thalassemia major (β‐TM) are at increased risk for sudden
cardiac death (SCD). Heterogeneity of ventricular repolarization is considered to provide an
electrophysiological substrate for malignant arrhythmias. QT dispersion (QTc‐D) and JT
dispersion (JTc‐D) are electrocardiographic parameters indicative of heterogeneity of
ventricular repolarization. The aim of our study was to evaluate the heterogeneity of
ventricular repolarization in patients with beta‐thalassemia and to test the hypothesis that an …
Abstract
Background:  Patients with beta‐thalassemia major (β‐TM) are at increased risk for sudden cardiac death (SCD). Heterogeneity of ventricular repolarization is considered to provide an electrophysiological substrate for malignant arrhythmias. QT dispersion (QTc‐D) and JT dispersion (JTc‐D) are electrocardiographic parameters indicative of heterogeneity of ventricular repolarization. The aim of our study was to evaluate the heterogeneity of ventricular repolarization in patients with beta‐thalassemia and to test the hypothesis that an abnormal QTc and JTc dispersion may predict SCD in this population.
Materials and Methods:  The study involved 51 patients with β‐TM (age 33.9 ± 8.4; 33 M) and 51 healthy subjects used as controls, matched for age, gender, and body mass index (BMI). Among the β‐TM group, 14 patients with β‐TM (age 27 ± 6.64; 11 M) died from SCD during follow‐up. For each patient, QTD and JTD intervals were calculated.
Results:  Compared to the healthy control group, β‐TM group presented increased values of the QTc‐D (65.36 ± 33.95 vs. 37, 62 ± 17.65; P < 0.003) and JTc‐D (74.64 ± 33.27 vs. 40.32 ± 12.45; P < 0.001). In the β‐TM sudden death group, QTc‐D and JTc‐D were significantly greater than in survived β‐TM group (92.70 ± 44.24 vs. 56.14 ± 23.80, P = 0.0001; 101.54 ± 47.93 vs. 64.47 ± 17.90, P = 0.0001). A cutoff value of 70 ms for QTc‐D had a sensitivity and specificity of 77% in identifying patients at risk for SCD. A cutoff value of 100 ms for JTc‐D had a sensitivity of 65% and a specificity of 94% in identifying this category of patients.
Conclusion:  β‐TM is associated with significant changes in heterogeneity of ventricular repolarization. QTc and JTc dispersion are useful markers of risk of SCD in patients with β‐TM.
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