Lack of Heart Iron Overload in Patients with Thalassemia Intermedia.

Abstract

Iron loading in patients with thalassemia intermedia occurs slowly and is mainly due to increased gastrointestinal iron absorption secondary to chronic anemia, while in patients with thalassemia major iron overload is faster and secondary to the chronic transfusion therapy. Moreover, iron accumulation in thalassemia intermedia is prevalent in parenchymal cells, while in thalassemia major iron derived from red cell breakdown firstly accumulates in the reticulo-endothelial cells and subsequently in the parenchymal cells. Although heart disease represents the main determinant of survival in beta thalassemias, the cardiac complications are different in the two clinical forms, that are thalassemia major and thalassemia intermedia. In this study we evaluated liver and iron overload in patients with thalassemia intermedia.We have studied 8 patients with thalassemia intermedia with a mean age of 36 ± 12 years. All these patients were homozygotes for the beta zero 39 non-sense mutation (C→T) and were never transfused or had received only sporadic transfusions (less than 10 blood units throughout their life). Myocardial iron (heart T2*, Anderson et al 2001), echocardiographic left ventricular ejection fraction, serum ferritin (mean of the last 5 years) and hemoglobin (mean of the last 2 years) have been evaluated in each patient. Hepatic iron content was determined in 5 patients with atomic absorption after liver biopsy. Six patients were on chelation therapy with subcutaneous desferrioxamine (mean 2 ± 1 grams/week).Mean ferritin was 637 ± 497 ng/ml and mean hemoglobin 8.0 ± 1.0 g/dl. Heart T2* was normal in all patients (mean 46 ± 11 msec, range 36 – 62 msec). The mean left ventricle ejection fraction was 61 ± 6 % (range 51 – 70 %). Echocardiogram showed in all the patients a mild enlargement of both ventricles. Three patients had pulmonary hypertension and two had an extrasystolic arrhythmia. To our knowledge this is the first study reporting the results of heart T2* in thalassemia intermedia. As a consequence of the mechanism and rate of accumulation patients with thalassemia intermedia do not have heart iron overload, while liver iron concentration is quite relevant. Cardiac complications in thalassemia intermedia are mainly due to the hyperdynamic circulation associated with chronic anemia and to pulmonary hypertension.