Onset of cardiac iron loading in pediatric patients with thalassemia major.

We reviewed cardiac T2* assessments from 77 thalassemia major patients between the ages of 2.5 and 18 years to study optimal timing of cardiac iron screening by magnetic resonance imaging. No patient under 9.5 years of age showed detectable cardiac iron in contrast to 36% of patients between the ages of 15-18 years old, corresponding to an odds-ratio of 1.28 (28%) per year. All patients with cardiac iron had received at least 35 grams of transfusional iron. Liver iron and ferritin failed to predict cardiac iron loading. Initiation of cardiac magnetic resonance imaging assessment should be determined according to age and transfusional burden rather than indices of iron overload. When appropriate chelation therapy has been administered since birth, cardiac magnetic resonance imaging can be postponed until 8 years of age when anesthesia is not required. Patients with suboptimal chelation, increased transfusional requirements, or who have initiated transfusions later in life should be tested sooner.