Onset of Cardiac Iron Loading in a Large and Homogeneous Cohort of Thalassemia Major Paediatric Patients

Magnetic Resonance Imaging (MRI) by the T2* technique allows highly reproducible and non invasive quantifications of myocardial iron burden and it is the gold standard for quantifying biventricular function parameters. It is important to determine the appropriate age to start MRI screening, because its high cost. Few data are available in the literature and they are contrasting. So the aim of this study was to address this issue in our paediatric patients with thalassemia major (TM).

We studied retrospectively 72 patients (47 males, 4.2–17.9 years old, mean age 13.03 ± 3.70 years), enrolled in the MIOT (Myocardial Iron Overload in Thalassemia) network. Myocardial iron overload was measured by T2* multislice multiecho technique. Biventricular function parameters were quantitatively evaluated by cine images.

The global heart T2* value was 29.7 ± 11.2 ms (range 6.2 – 48.0 ms). No significant correlation was found between global heart T2* value and age (see figure). The global heart T2* value did not show significant differences according to the sex (male 30.2 ± 11.0 ms versus female 28.7 ± 11.8 ms, P=0.568). Sixteen patients (22%) showed an abnormal global heart T2* value (<20 ms) and none of them was under 8 years of age. Global heart T2* value was negatively correlated with mean serum ferritin levels. Odds Ratio for high serum ferritin levels (≥ 1500 ng/ml) was 8.4 (1.01–69.37, OR 95%CI) for abnormal global heart T2* values (< 20 ms). The global heart T2* value did not show a significant difference with respect to the chelation therapy (P=0.322). No significant correlations were found between the global heart T2* values and the bi-atrial areas or the LV and RV morphological and functional parameters. Eight patients showed a left ventricular (LV) ejection fraction (EF) < 57% and none of them was under 7 years of age. Two patients showed a right ventricular (RV) EF < 52% and none of them was under 14 years of age.

The MRI screening for both cardiac iron overload and function assessment can be started for TM patients at the age of 7 years. At this age not sedation is generally needed. If the availability of cardiac MRI is low, the serum ferritin levels could be used as a discriminating factor.

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No relevant conflicts of interest to declare.