Observational study of iron overload as assessed by magnetic resonance imaging in an adult population of transfusion-dependent patients with beta thalassaemia: significant association between low cardiac T2*< 10 ms and cardiac events

Background: Thalassaemia major patients usually die from cardiac haemosiderosis. Improved strategies are required to modify this risk. Aims: To assess the significance of cardiac iron overload in patients with β thalassaemia. Method: Observational study of cardiac iron overload as assessed by magnetic resonance imaging (MRI) cardiac T2* relaxometry in 30 adult patients with transfusion-dependent β thalassaemia. Results: 11/30 patients (37%) had cardiac T2* 20 ms. There was significant inverse correlation between T2* values and values for serum ferritin (SF) and liver iron concentration (LIC) and positive correlation with left ventricular ejection fraction (LVEF). Median LVEF values were 49% in patients with T2* 10 ms (P= 0.02). Very low T2* values 10 ms (P= 0.003 Fisher's exact test; P= 0.002 log rank Kaplan-Meier time to event analysis). There was no significant association between T2* 2500 µg/L and LIC (evaluated at thresholds of >7 or >15 mg/g dry weight). Conclusion: Very low cardiac T2* values <10 ms are common in adults with β thalassaemia and are significantly associated with risk of cardiac events. This permits the use of individually targeted chelation strategies which are more effective in removing cardiac iron.