Purpose: The main cause of death in beta-thalassemia major patients is congestive heart failure which is traditionally referred to myocardial iron overload. Recently, some investigators have found that cardiac failure is not caused by the iron overload. In their opinion, left-sided heart failure develops years after the onset of acute myocarditis and might be related to a late autoimmune process. Right-sided heart failure is related to the combination of left ventricular diastolic restriction and pulmonary hypertension. The aim of this work is to study myocardial iron overload by MRI and to correlate the signal intensity changes of the myocardium with cardiac function.
Material and methods: Sixteen patients with beta-thalassemia major were examined with a .5 super-conducting unit. SE and cine-GE sequences were used in the 4 chamber and 2 chamber views. Left ventirclar ejection fraction (EF) was calculated by using the biplane area-length method. Right ventricular size was assessed by measuring the end-diastolic anteroposterior diameter (APD). Myocardial signal intensity was evaluated qualitatively and quantitatively (myocardium/subcutaneous fat) in all the beta-thalassemia patients and in 10 normal volunteers.
Results: Left ventricular function was decreased (EF < 55%) in 2/16 patients. The right ventricle was dilated in 5/16 patients (APD > 42 mm). The myocardium had a lower signal intensity than that of normal volunteers in 15/16 patients. No statistical correlation was found between myocardial signal intensity and serum ferritine levels or cardiac function.
Conclusions: The small number of patients in our series does not allow any definitive statements. However, our results show that cardiac function is not influenced by myocardial iron overload.