Effect of Iron Chelators on Cardiac Iron Assessed by MR T2* in Thalassemia Major

Introduction: Cardiac iron overload secondary to red blood cell transfusion is a common complication of thalassemia major despite the wide use of chelation therapy and cardiac disease still account for up to 70% of deaths in these patients. Furthermore, myocardial siderosis can be accurately assessed by cardiovascular magnetic resonance (CMR) using T2* sequence. Available chelators seem to have unique profiles of organ iron removal. We report a retrospective analysis of the effect of three available chelators on cardiac iron in patients with thalassemia major.

Methods: Fifty-two patients on subcutaneous desferrioxamine (DFO), 28 on deferiprone (DFP) and 28 on deferasirox (DFX) are included in the study. DFO was administered at a mean dosage of 36 ± 8 mg/kg/d for 10 to 14 hours per day for 21 ± 13 months, DFP at 86 ± 10 mg/kg/d for 23 ± 12 months and DFX at 27 ± 6mg/kg/d for 15 ± 5 months. T2* was measured according to Westwood et al (2005). Entry criteria included in each patient a value of T2* lower than 20 ms at baseline or at final assessment. Left ventricular ejection fraction (LVEF) was measured by echocardiography.

Results: At baseline, the 3 treatment groups did not show any significant difference in age blood consumption and cardiac T2* (DFO group: 13.4 ± 4.5 ms, DFP 13.9 ± 3.7 and DFX 12.8 ± 3.7; p=0.573).. At the last evaluation mean cardiac T2* was slightly increased in patients on DFO (13.9 ± 8.6 ms, p=0.8) and in those on DFX (13.8 ± 4.4 ms, p=0.04), while was substantially increased in patients on DFP (21.7 ± 9.2 ms, p=0.001). To correct for the different duration of treatment we calculated the percentage monthly cardiac T2* changes that were significantly higher in patients on DFP (1,84 ± 1.94), as compared to patients on DFO (0.2 3 ± 2.15) or DFX (0.45 ± 1.49) (p<0.001). No differences were detected between mean LVEF at baseline and at last assessment in all 3 groups.

Conclusions: In this retrospective study monotherapy with deferiprone was significantly more effective than desferrioxamine and deferasirox in alleviating myocardial siderosis in patients with beta-thalassemia major. Further studies are needed to understand if the cardiac T2* changes are influenced by the chelator dosages.