Cardiac magnetic resonance in transfusion dependent thalassaemia: assessment of iron load and relationship to left ventricular ejection fraction.

Cardiac Magnetic Resonance (CMR) has replaced all other surrogate measurements in the determination of transfusional cardiac iron overload in patients with thalassaemia major. We aimed to determine the diagnostic value of CMR T2* with respect to cardiac dysfunction (CD) as determined by CMR-derived left ventricular ejection fraction (LVEF). Cardiac T2* values and LVEF measured by CMR were recorded in 303 patients with thalassaemia major, at the time of their first CMR. T2* was correlated with LVEF (regression coefficient: 0·57, P<0·001). The prevalence of CD was 32·9% in patients with T2*≤8 ms, 12·5% in patients with T2*>8 ms and ≤14 ms and reduced to 9·1% in patients with T2* between 14-20 ms. As the probability of CD is progressively, and not suddenly, reduced with increasing values of T2*, CMR has a limited diagnostic value for CD (Receiver operating characteristic analysis, area under the curve = 0·68). Patients with cardiac T2*≤8 ms require careful and intensive management. This risk decreases with increasing values of T2* but even in mildly loaded patients the probability of impaired LVEF is not negligible.