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

Abstract

Thalassaemia major patients usually die from cardiac haemosiderosis. Improved strategies are required to modify this risk. To assess the significance of cardiac iron overload in patients with beta thalassaemia. Observational study of cardiac iron overload as assessed by magnetic resonance imaging (MRI) cardiac T2* relaxometry in 30 adult patients with transfusion-dependent beta thalassaemia. 11/30 patients (37%) had cardiac T2* < 10 ms, 8/30 (27%) in range 10-20 ms and 11/30 (37%) > 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 and 58% in patients with T2* > 10 ms (P = 0.02). Very low T2* values <10 ms were strongly associated with the occurrence of cardiac events (congestive heart failure, arrhythmia, cardiac death): occurring in 5/11 patients with T2* < l0 ms and in 0/19 in patients with T2* > 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* < 10 ms or cardiac events and traditional measures of iron overload, such as SF levels >2500 mg/L and LIC (evaluated at thresholds of >7 or >15 mg/g dry weight). Very low cardiac T2* values <10 ms are common in adults with beta 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.