Cardiac T2* magnetic resonance imaging (MRI) is the gold standard to determine myocardial iron overload. As availability of Cardiac T2* is not uniform across developing nations, our strategy was to identify a more accessible and cost effective tool to assess myocardial iron accumulation. As children with transfusion-dependent thalassemia also experience various electrocardiographic abnormalities, we performed electrocardiography (ECG) as well as Cardiac T2* MRI on all children registered in our thalassemia unit.
Forty-eight transfusion-dependent thalassemia children with transfusion burden ≥12 times/y (6 to 19 y) in the Thalassemia Unit of the Division of Hematology Oncology, Department of Pediatrics were enrolled. Patients were divided into 3 groups based on severity of T2* value, that is group I (T2*<10), group II (T2* 10 to 20), group III (T2*>20). A T2* value >20 was taken as normal. ECG and serum ferritin was also performed on the day of MRI.
Among the various ECG parameters, QRS duration, and QTc interval were significantly increased if cardiac iron overload was high with a P-value of 0.036 and 0.000, respectively. Also, high serum ferritin predicted a decline in T2* value with a P-value of 0.001. QT interval and QTc interval significantly correlated inversely with T2* (P=0.042, r=-0.295 and P=0.002, r=-0.446, respectively) but not QRS duration (P=0.05, r=-0.282). Serum ferritin also was found to have a significant inverse correlation with T2* value (P=0.000, r=-0.497).
Abnormalities on ECG, that is prolongation of QRS duration, QT interval, and QTc interval were significantly associated with cardiac iron overload, that is decrease in the value of Cardiac T2* in our study.