Cardiac involvement by CMR in different genotypic groups of thalassemia major patients.

Beta thalassemia major (β-TM) displays a great deal of phenotypic heterogeneity, not fully investigated in terms of cause-effect. We aimed to detect if different genotypic groups could be related to different levels of cardiac impairment, evaluated by cardiovascular magnetic resonance (CMR). We considered 671 β-TM patients (age 30.1 years, 52.9% females) consecutively enrolled in the Myocardial Iron Overload (MIO) in Thalassemia network. MIO was assessed by T2* technique. Biventricular function was quantified by cine images. Myocardial fibrosis was evaluated by late gadolinium enhancement (LGE) technique. Three groups of patients were identified: heterozygotes β/β° (N = 279), homozygotes β  (N = 154), homozygotes β° (N = 238). Transfusional needs resulted significantly lower in homozygous β  TM patients when compared to the other groups. The homozygous β  group versus the heterozygous and homozygous β° groups showed higher global heart T2* values (P < 0.0001) and a lower number of patients with a global heart T2* value<20 ms (P < 0.001). The homozygotes β  showed a lower number of patients with a pathological left ventricular ejection fraction (LVEF) than the other two groups (P < 0.05). The β/β  TM patients showed less MIO and a concordant better systolic heart function. These data support the knowledge of different genotypic groups in the management of β-TM patients.