International survey of T2* cardiovascular magnetic resonance in β-thalassemia major

Accumulation of myocardial iron is the cause of heart failure and early death in most transfused thalassemia major patients. T2* cardiovascular magnetic resonance provides calibrated, reproducible measurements of myocardial iron. However, there are few data regarding myocardial iron loading and its relation to outcome across the world. A survey is reported of 3,095 patients in 27 worldwide centers using T2* cardiovascular magnetic resonance. Data on baseline T2* and numbers of patients with symptoms of heart failure at first scan (defined as symptoms and signs of heart failure with objective evidence of left ventricular dysfunction) were requested together with more detailed information about patients who subsequently developed heart failure or died. At first scan, 20.6% had severe myocardial iron (T2*≤ 10 ms), 22.8% had moderate myocardial iron (T2* 10-20 ms) and 56.6% of patients had no iron loading (T2*>20 ms). There was significant geographical variation in myocardial iron loading (24.8-52.6%; P<0.001). At first scan, 85 (2.9%) of 2,915 patients were reported to have heart failure (81.2% had T2* <10 ms; 98.8% had T2*