Discrepancy in patterns of myocardial involvement in beta-thalassaemia vs. sickle cell anaemia.

Different mechanisms contribute to myocardial dysfunction in sickle cell disease [SCD] and beta thalassaemia major [TM]. TM mainly involves the highly vascular subepicardium by iron load and SCD mainly operates by inducing ischaemia in the relatively ischaemic subendocardium. The aim of this article was to determine if pattern of left ventricular [LV] dysfunction differ among the two groups of patients. Forty TM and 40 SCD patients and 40 age- and surface area-matched controls were subjected to conventional echocardiography, 2D Speckle tracking myocardial layer strain discriminating echocardiography (MLSD-STE) which is able to discriminate if myocardial dysfunction is predominantly subepicardial or subendocardial and 3D echocardiography for ejection fraction assessment as well as haemoglobin, ferritin, and lactate dehydrogenase levels. TM patients had a deeper subepicardial dysfunction while SCD had prevalent subendocardial dysfunction, epicardial GLS (TM: -10.9 ± 2 vs. SCD: 19.9 ± 1.7; value < 0.01); endocardial GLS (TM: -19.9 ± 1.7 vs. SCD: -10.6 ± 1.6, value < 0.01). This study points towards divergent microcirculatory mechanisms in the pathogenesis of myocardial dysfunction in haemoglobinopathies. It shows predominant subendocardial dysfunction with underlying ischaemia of SCD and prevalent subepicardial iron-induced injury in cases of TM.