Iron overload is a well known complication in multitransfused patients with MDS, contributing to morbidity and mortality. The presence of non transferrin bound iron (NTBI), a catalyst in generation of reactive oxygen species, has also been documented (

Winder et al, Blood 2003;102:916a
), resulting in impaired function of the mitochondria in the heart. The technology of T2* MRI allows accurate measurements of iron in different body organs. Studies in thalassemia demonstrated there was no direct correlation between the amount of iron deposited in liver and heart. The purpose of the present study was to measure by T2* the degree of iron overload in the heart and liver of transfused patients with the sideroblastic form of MDS.

Methods: MRI measurements were performed using 1.5T GE MRI systems. Scans included left ventricular volumetric and function measurements, and a breath-hold multi echo gradient echo T2* sequence. T2* values across regions of interest located at the cardiac septum and at the subphrenic part of liver were evaluated (

Anderson et al, Eur Heart J 22:2171,2001
).

Results: Reported myocardial and liver T2* values for healthy volunteers are 52 ± 16 ms and 33 ± 7 ms, respectively, where cardiac iron overload is below 20 ms. The present results in the controls are in concordance with those values and displayed in the table:

DiagnosisAge/ GenderNo. of PC unitsFerritin (ng/ml)LVEF (%)T2* liver (ms)T2* myocard (ms)
RARS 75/M 67 3920 70 3–5 42–46 
RARS 87/M 50 1853 63 <2 15–20 
RARS 84/F 58 1790 59 <2 33–40 
RARS 80/M 30 NA 15 18–21 47–50 
RARS 69/M 43 1930 70 25–35 35–50 
HEMPAS 52/F 0 1280 46 <2 3–5 
Controls (4) 34–68/ 3F,1M 0 82–196  27–37 41–47 
DiagnosisAge/ GenderNo. of PC unitsFerritin (ng/ml)LVEF (%)T2* liver (ms)T2* myocard (ms)
RARS 75/M 67 3920 70 3–5 42–46 
RARS 87/M 50 1853 63 <2 15–20 
RARS 84/F 58 1790 59 <2 33–40 
RARS 80/M 30 NA 15 18–21 47–50 
RARS 69/M 43 1930 70 25–35 35–50 
HEMPAS 52/F 0 1280 46 <2 3–5 
Controls (4) 34–68/ 3F,1M 0 82–196  27–37 41–47 
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In 4 out of 5 MDS patients who received up to 67 transfusions throughout a period of 1 to 5 years, there was no evidence of iron accumulation in the heart, while in one untransfused patient with congenital dyserythropoietic anemia type II (HEMPAS) despite chelation with Desferrioxamine and Deferiprone there was a lot of iron in the heart. Moreover, in spite their advanced age, 4 out of 5 patients had normal left ventricular ejection fraction. The one exception (LVEF-15%) had severe atherosclerotic heart disease. On the other hand, 4 of 5 patients had a lot of iron in their liver. There was no correlation between serum ferritin levels and the T2* values in the heart.

Conclusions: These preliminary results suggest that iron accumulation in elderly patients with refractory anemia with ringed sideroblasts (RARS) who received more than 30 blood units is primarily in the liver and not in the heart. In order for the heart to be involved higher number of transfusions and/or a longer duration of the disease may be required. Moreover, the mechanism of iron deposition in the heart seems to be different in congenital anemias, where intravascular premature hemolysis results in release of iron, and accumulation in the heart even without transfusions. The present findings indicate that there is a rationale for iron chelation in RARS patients at least from the liver and possibly, with longer duration of the disease, also from the heart. The mode of chelation will have to be designed accordingly, since the efficacy of the available chelators is not the same on the liver and heart.

Topics:
anemia, sideroblastic, heart, iron overload, magnetic resonance imaging, older adult, refractory anemia with sideroblasts, transverse spin relaxation time, iron, blood transfusion, congenital dyserythropoietic anemia, type ii

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Corresponding author

2005, The American Society of Hematology
2005
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