Chelation therapy reduces cardiac iron overload earlier than liver iron overload in patients with thalassemia major, according to research published in Hematology, Transfusion and Cell Therapy.
Despite advances in transfusions and iron chelation, heart disease is still the leading cause of death in patients with thalassemia major. Serum ferritin is a sensitive tool to detect iron overload, but it doesn’t reflect iron concentrations within each organ. Magnetic resonance imaging (MRI) T2 is a way to measure the iron concentration in the heart, as well as the liver and pancreas to monitor for iron overload.
The study analyzed chelation protocols in a prospective, observational, real-world study of 136 patients with thalassemia in Brazil being treated with iron chelation. The researchers measured serum ferritin and iron concentrations in the heart, liver, and pancreas with MRI T2.
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A total of 126 patients had thalassemia major, and 10 had intermedia thalassemia. The median age of patients was 18 years, and the study included a median follow-up of 1.2 years.
Patients on regular transfusion regimens often have some level of iron overload. At baseline, the liver was most commonly affected by iron overload (99.3% of patients), followed by pancreas (74.3%), and the heart (36%).
Ferritin levels decreased during the study period with chelation therapy. Ferritin was moderately correlated with liver iron concentrations (r = 0.527). The authors suggested cutoff values for referring patients for cardiac T2 MRI in lower-income countries. R2 pancreas of ≤50 hertz and ferritin ≤1222 ng/ml had a negative predictive value of 98% for cardiac siderosis.
The real-world nature of this study suggested compliance problems, as some patients had new cases of pancreatic and myocardium siderosis.
Improvements in liver siderosis were slower than in the myocardium. Iron improvement was seen only in the subgroup with cardiac siderosis in this study. This may be because patients with cardiac iron overload may be more compliant with therapy, although this is only a hypothesis by the study authors.
The study’s short-term follow-up period limits conclusions that can be drawn about compliance and long-term reductions in iron.
The authors suggested that MRI T2 is useful to guide chelation therapy, but is limited in the liver and pancreas because of interference of fat tissue.
Reference
Chapchap EC, Silva MMA, de Assis RA, et al. Cardiac iron overload evaluation in thalassaemic patients using T2* magnetic resonance imaging following chelation therapy: a multicentre cross-sectional study. Hematol Transfus Cell Ther. 2021;S2531-1379(21)00043-2. doi:10.1016/j.htct.2021.01.014
