Myocardial iron load measured by cardiac magnetic resonance imaging to evaluate cardiac systolic function in thalassemia

BACKGROUND: The assessment of cardiac iron overload in thalassemia major has been considered as an important predictive factor of heart injury. The magnetic resonance imaging (MRI)-derived relaxation time parameter (T۲*) varies inversely with iron level, and elevated myocardial iron levels by T۲* are associated with depressed left ventricular (LV) ejection fraction (EF). We compared echocardiographic (ECHO) indices of systolic function to myocardial T۲* in these patients. METHODS: A cross-sectional database review identified ۲۰۰ consecutive patients with thalassemia who underwent both ECHO and MRI T۲* assessment. RESULTS: There was a negative correlation between T۲* measurement and ECHO EF (r = −۰.۳۸۹, P < ۰.۰۰۱). Using a cutoff value of ۵۰% for differentiating LV normal and abnormal function by ECHO, T۲* MRI had a sensitivity of ۵۷.۱%, a specificity of ۸۹.۹%, and an accuracy of ۸۶.۵% for predicting LV dysfunction. Receiver operating characteristic analysis showed that cardiac iron measurement had an acceptable value for discriminating normal and abnormal LV function (area under the curve = ۰.۷۶۹, ۹۵% confidence interval: ۰.۶۵۳-۰.۸۸۵). With respect to the relationship between serum ferritin level and cardiac iron value, the level of serum ferritin was positively correlated with the level of cardiac iron load (r = ۰.۲۵۷, P < ۰.۰۰۱). Conclusion: Myocardial iron load assessed by MRI T۲* is associated with deterioration of the LV function assessed by ECHO with a high specificity and moderate sensitivity. It is important to identify the thalassemic patients with a risk of iron overloaded cardiomyopathy and heart failure.  

Keywords:

Thalassemia , Iron Overload , Magnetic Resonance Imaging , Ferritin , Accuracy