Extramedullary hematopoiesis is associated with lower cardiac iron loading in chronically transfused thalassemia patients

Abstract

The aim of this study was to evaluate, in a large cohort of chronically transfused patients, whether the presence of extramedullary hematopoiesis (EMH) accounts for the typical patterns of cardiac iron distribution and/or cardiac function parameters. We retrospectively selected 1,266 thalassemia major patients who had undergone regular transfusions (611 men and 655 women; mean age: 31.3 6 8.9 years, range: 4.2-66.6 years) and were consecutively enrolled within the Myocardial Iron Overload in Thalassemia network. The presence of EMH was evaluated based on steady-state free precession sequences; cardiac and liver iron overloads were quantified using a multiecho T2* approach; cardiac function parameters and pulmonary diameter were quantified using the steady-state free precession sequences; and myocardial fibrosis was evaluated using the late gadolinium enhancement technique. EMH was detected in 167 (13.2%) patients. The EMH1 patients had significantly lower cardiac iron overload than that of the EMH2 patients (P 5 0.003). The patterns of cardiac iron distribution were significantly different in the EMH1 and EMH2 patients (P < 0.0001), with a higher prevalence of patients with no myocardial iron overload and heterogeneous myocardial iron overload and no significant global heart iron in the EMH1 group EMH1 patients had a significantly higher left ventricle mass index (P 5 0.001) and a significantly higher pulmonary artery diameter (P 5 0.002). In conclusion, in regularly transfused thalassemia patients, EMH was common and was associated with a thalassemia intermedia-like pattern of cardiac iron deposition despite regular transfusion therapy.

Presence of the IVS-I-6-Mutated Allele in Beta-Thalassemia Major Patients Correlates with Extramedullary Hematopoiesis Incidence

“…At the same time, in a retrospective study in a large cohort by Ricchi et al [34], EMH was detected in 13.2% of regularly transfused TM patients, in accordance with the prevalence calculated in the present study. Besides, in a previous study, Ricchi et al [78] estimated an even higher prevalence of EMH among a cohort of polytransfused thalassemic patients.…”

“…Furthermore, neither sex was correlated with EMH although, according to the pertinent literature, EMH predominates in males with a male:female ratio of 2.5:1 [35] to 6:1 [24]. Last, EMH was not correlated with cardiac iron accumulation, which is in contrast to the results by Ricchi et al [34] where EMH was associated with lower cardiac iron loading.…”

“…The present study aims to record the incidence of EMH in chronically transfused TM patients followed at our institution and to investigate possible risk factors associated with its occurrence. To our knowledge, aside from a recent publication by Ricchi et al [34], this is the sole study that stresses a profound incidence of asymptomatic EMH in a solid group of well-transfused TM patients. Moreover, the reported prevalence may slightly underestimate the real burden of EMH as it was estimated on the basis of regular routine hepatic and cardiac imaging.…”

Extramedullary Haematopoiesis in Patients with Thalassaemia Major: Should We Search for It Regularly?

“…Nevertheless, 2 recent Italian papers highlighted that EMH could be detected more frequently among patients who regularly undergo transfusion [2,3]; cases with spinal-cord compression were also described [3,4]. In a retrospective study, EMH was detected incidentally because most of the patients underwent computed tomography or magnetic resonance imaging (MRI) scanning for a variety of clinical indications [3].…”

“…In a retrospective study, EMH was detected incidentally because most of the patients underwent computed tomography or magnetic resonance imaging (MRI) scanning for a variety of clinical indications [3]. In the MIOT (Myocardial Iron Overload Thalassaemia) study, EMH was detected following the use of MRI to estimate iron overload [2]. In these studies, the presence of EMH was associated with splenectomy, a higher nucleated red blood cell count, higher levels of soluble transferrin receptor, and older age at the first transfusion.…”