Cardiac iron overload in sickle-cell disease

Multiparametric Cardiac Magnetic Resonance Assessment in Sickle Beta Thalassemia

Cardiac involvement in sickle beta thalassemia (Sβ-thal) patients has been poorly investigated. We aimed to evaluate cardiac function and myocardial iron overload by cardiovascular magnetic resonance (CMR) in patients with Sβ-thal. One-hundred and eleven Sβ-thal patients consecutively enrolled in the Myocardial Iron Overload in Thalassemia (MIOT) network were studied and compared with 46 sickle cell anemia (SCA) patients and with 111 gender- and age- matched healthy volunteers. Cine images were acquired to quantify biventricular function. Myocardial iron overload (MIO) was assessed by the T2* technique, while macroscopic myocardial fibrosis was evaluated by the late gadolinium enhancement (LGE) technique. In Sβ-thal and SCA patients, the morphological and functional CMR parameters were not significantly different, except for the left atrial area and left ventricular (LV) stroke volume, indexed by body surface area (p = 0.023 and p = 0.048, respectively), which were significantly higher in SCA patients. No significant differences between the two groups were found in terms of myocardial iron overload and macroscopic myocardial fibrosis. When compared to healthy subjects, Sβ-thal patients showed significantly higher bi-atrial and biventricular parameters, except for LV ejection fraction, which was significantly lower. The CMR analysis confirmed that Sβ-thal and SCA patients are phenotypically similar. Since Sβ-thal patients showed markedly different morphological and functional indices from healthy subjects, it would be useful to identify Sβ-thal/SCA-specific bi-atrial and biventricular reference values.

CHMMOTv1 - cardiac and hepatic multi-echo (T2*) MRI images and clinical dataset for Iron overload on thalassemia patients

INTRODUCTION

Regarding deep learning networks in medical sciences for improving diagnosis and treatment purposes and the existence of minimal resources for them, we decided to provide a set of magnetic resonance images of the cardiac and hepatic organs.

DATABASE DESCRIPTION

The dataset included 124 patients (67 women and 57 men) with thalassemia (THM), the age range of (5-52) years. Patients were divided into two groups: with follow-up (1-5 times) at time intervals of about (5-6) months and without follow-up. T2* and, R2* values, the results of the Cardiac and Hepatic overload report (normal, mild, moderate, severe), and laboratory tests including Ferritin, Bilirubin (D, and T), AST, ALT, and ALP levels were provided as an Excel file. Also, the details of the patients' Echocardiogram data have been made available. This dataset CHMMOTv1) has been published in Mendeley Dataverse and also is accessible through the web at: http://databiox.com .

The Role of Inflammation in The Cellular and Molecular Mechanisms of Cardiopulmonary Complications of Sickle Cell Disease

Cardiopulmonary complications remain the major cause of mortality despite newer therapies and improvements in the lifespan of patients with sickle cell disease (SCD). Inflammation has been identified as a major risk modifier in the pathogenesis of SCD-associated cardiopulmonary complications in recent mechanistic and observational studies. In this review, we discuss recent cellular and molecular mechanisms of cardiopulmonary complications in SCD and summarize the most recent evidence from clinical and laboratory studies. We emphasize the role of inflammation in the onset and progression of these complications to better understand the underlying pathobiological processes. We also discuss future basic and translational research in addressing questions about the complex role of inflammation in the development of SCD cardiopulmonary complications, which may lead to promising therapies and reduce morbidity and mortality in this vulnerable population.

Prognostic value of multiparametric cardiac magnetic resonance in sickle cell patients

The aim of this multicenter study was to prospectively assess the predictive value of multiparametric cardiac magnetic resonance (CMR) for cardiovascular complications in sickle cell disease (SCD) patients. Among all patients with hemoglobinopathies consecutively enrolled in the Myocardial Iron Overload in Thalassemia (MIOT) Network, we selected 102 SCD patients (34.38 ± 12.67 years, 49 females). Myocardial iron overload (MIO) was measured by the multislice multiecho T2* technique. Atrial dimensions and biventricular function parameters were quantified by cine images. Late gadolinium enhancement (LGE) images were acquired to detect focal myocardial fibrosis. At baseline CMR, only two patients had significant MIO (global heart T2* < 20 ms). During a mean follow-up of 63.01 ± 24.95 months, 11 cardiovascular events (10.8%) were registered: 3 pulmonary hypertension, 2 supraventricular arrhythmias, 1 heart failure, 1 death for heart failure, 1 pulmonary embolism, 1 peripheral vascular disease, 1 transient ischemic attack, and 1 death after acute chest syndrome. In the multivariate analysis, the independent CMR predictors of cardiovascular events were left ventricular (LV) ejection fraction (hazard ratio-HR = 0.88; p = 0.025) and right ventricular (RV) mass index (HR = 1.09; p = 0.047). According to the receiver-operating characteristic curve analysis for adverse events, an LV ejection fraction < 58.9% and an RV mass index > 31 g/m² were optimal cut-off values. Reduced left ventricular ejection fraction and increased right ventricular mass index showed a significant prognostic value in patients with SCD. Our data seem to suggest that CMR may be added as a screening tool for identifying SCD patients at high risk for cardiopulmonary and vascular diseases.

Adverse events of red blood cell transfusions in patients with sickle cell disease

Blood transfusion is a common medical intervention for patients with sickle cell disease (SCD) and disease related complications. While patients with SCD are at risk for all transfusion related adverse events defined by the National Healthcare Safety Network (NHSN) Biovigilance Component Hemovigilance Module Surveillance Protocol, they are uniquely susceptible to certain adverse events. This review discusses risk factors, mitigation strategies, and management recommendations for alloimmunization, hemolytic transfusion reactions, hyperviscosity and transfusion-associated iron overload in the context of SCD.

The role of MRI-R2* in the detection of subclinical pancreatic iron loading among transfusion-dependent sickle cell disease patients and correlation with hepatic and cardiac iron loading

Objectives

Pancreatic reserve could be preserved by early assessment of pancreatic iron overload among transfusion-dependent sickle cell disease (SCD) patients. This study aimed to measure pancreatic iron load and correlate its value with patients’ laboratory and radiological markers of iron overload.

Materials and methods

Sixty-six SCD children and young adults underwent MRI T2* relaxometry using a simple mathematical spreadsheet and laboratory assessment.

Results

The results indicated moderate-to-severe hepatic iron overload among 65.2% of studied cases. None had cardiac iron overload. Normal-to-mild iron overload was present in the pancreas in 86% of cases, and 50% had elevated serum ferritin > 2500 ug/L. There was no significant correlation between pancreatic R2* level, serum ferritin, and hepatic iron overload. Patients with higher levels of hemolysis markers and lower pre-transfusion hemoglobin levels showed moderate-to-severe pancreatic iron overload.

Conclusion

Chronically transfused patients with SCD have a high frequency of iron overload complications including pancreatic iron deposition, thereby necessitating proper monitoring of the body’s overall iron balance as well as detection of extrahepatic iron depositions.

Relationship between pancreatic iron overload, glucose metabolism and cardiac complications in sickle cell disease: An Italian multicentre study

OBJECTIVES

Evidence about the cross-talk between iron, glucose metabolism, and cardiac disease is increasing. We aimed to explore the link of pancreatic iron by Magnetic Resonance Imaging (MRI) with glucose metabolism and cardiac complications (CC) in sickle cell disease (SCD) patients.

METHODS

We considered 70 SCD patients consecutively enrolled in the Extension-Myocardial Iron Overload in Thalassemia Network. Iron overload was quantified by R2* technique and biventricular function by cine images. Macroscopic myocardial fibrosis was evaluated by late gadolinium enhancement technique. Glucose metabolism was assessed by the oral glucose tolerance test.

RESULTS

Patients with an altered glucose metabolism showed a significantly higher pancreas R2* than patients with normal glucose metabolism. Pancreatic siderosis emerged as a risk factor for the development of metabolic alterations (OddsRatio 8.25, 95%confidence intervals 1.51-45.1; p = .015). Global pancreas R2* values were directly correlated with mean serum ferritin levels and liver iron concentration. Global pancreas R2* was not significantly associated with global heart R2* and macroscopic myocardial fibrosis. Patients with history of CC showed a significantly higher global pancreas R2* than patients with no CC.

CONCLUSIONS

Our findings support the evaluation of pancreatic R2* by MRI in SCD patients to prevent the development of metabolic and cardiac disorders.

Cardiovascular consequences of sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder caused by a single point mutation within the beta globin gene. As a result of this mutation, hemoglobin polymerizes under low oxygen conditions causing red blood cells to deform, become more adhesive, and increase in rigidity, which affects blood flow dynamics. This process leads to enhanced red blood cell interactions with the endothelium and contributes to vaso-occlusion formation. Although traditionally defined as a red blood cell disorder, individuals with SCD are affected by numerous clinical consequences including stroke, painful crisis episodes, bone infarctions, and several organ-specific complications. Elevated cardiac output, endothelium activation along with the sickling process, and the vaso-occlusion events pose strains on the cardiovascular system. We will present a review of the cardiovascular consequences of sickle cell disease and show connections with the vasculopathy related to SCD. We will also highlight biophysical properties and engineering tools that have been used to characterize the disease. Finally, we will discuss therapies for SCD and potential implications on SCD cardiomyopathy.

Quantitative susceptibility mapping (QSM) of the cardiovascular system: challenges and perspectives

Quantitative susceptibility mapping (QSM) is a powerful, non-invasive, magnetic resonance imaging (MRI) technique that relies on measurement of magnetic susceptibility. So far, QSM has been employed mostly to study neurological disorders characterized by iron accumulation, such as Parkinson's and Alzheimer's diseases. Nonetheless, QSM allows mapping key indicators of cardiac disease such as blood oxygenation and myocardial iron content. For this reason, the application of QSM offers an unprecedented opportunity to gain a better understanding of the pathophysiological changes associated with cardiovascular disease and to monitor their evolution and response to treatment. Recent studies on cardiovascular QSM have shown the feasibility of a non-invasive assessment of blood oxygenation, myocardial iron content and myocardial fibre orientation, as well as carotid plaque composition. Significant technical challenges remain, the most evident of which are related to cardiac and respiratory motion, blood flow, chemical shift effects and susceptibility artefacts. Significant work is ongoing to overcome these challenges and integrate the QSM technique into clinical practice in the cardiovascular field.

Medical and Non-medical Costs of Sickle Cell Disease and Treatments from a US Perspective: A Systematic Review and Landscape Analysis

BACKGROUND

Sickle cell disease (SCD) is a complex genetic disorder that manifests in infancy and progresses throughout life in the form of acute and chronic complications. As the upfront costs of potentially curative, genetic therapies will likely be high, an assessment and comprehensive characterization of the medical and non-medical cost burden will inform future decision making.

OBJECTIVE

We sought to systematically summarize the existing literature surrounding SCD medical and non-medical costs.

METHODS

We searched MEDLINE and EMBASE (2008-2020) and identified US-based studies that detailed medical or non-medical costs. Eligible studies provided empirical estimates about any aspect of cost or SCD individuals of all ages and their caregivers. Study quality was assessed using the Newcastle-Ottawa Scale, and costs were adjusted to 2019 US$.

RESULTS

Search queries returned 479 studies, with 342 from medical burden searches and 137 from non-medical burden searches, respectively. Herein, we report the results of the 40 studies that contained relevant cost information: 39 detailed medical costs and 1 detailed non-medical costs. Costs were higher for SCD patients when compared with non-SCD individuals (cost difference range: $6636-$63,436 annually). The highest medical cost component for SCD patients was inpatient ($11,978-$59,851 annually), followed by outpatient and then pharmacy. No studies characterized the cost burden throughout the lifetime disease trajectory of an SCD individual, and no studies captured caregiver or productivity costs.

CONCLUSION

Our results reveal an incomplete characterization of medical and non-medical costs within SCD. A deeper understanding of the medical and non-medical cost burden requires completion of additional studies that capture the burden across the patient's lifetime, in addition to expression of the impact of existing and emergent health technologies on disease trajectory.

T2* assessment of the three coronary artery territories of the left ventricular wall by different monoexponential truncation methods

Objectives

This study aimed at evaluating left ventricular myocardial pixel-wise T2* using two truncation methods for different iron deposition T2* ranges and comparison of segmental T2* in different coronary artery territories.

Material and methods

Bright blood multi-gradient echo data of 30 patients were quantified by pixel-wise monoexponential T2* fitting with its R2 and SNR truncation. T2* was analyzed at different iron classifications. At low iron classification, T2* values were also analyzed by coronary artery territories.

Results

The right coronary artery has a significantly higher T2* value than the other coronary artery territories. No significant difference was found in classifying severe iron by the two truncation methods in any myocardial region, whereas in moderate iron, it is only apparent at septal segments. The R2 truncation produces a significantly higher T2* value than the SNR method when low iron is indicated.

Conclusion

Clear T2* differentiation between the three coronary territories by the two truncation methods is demonstrated. The two truncation methods can be used interchangeably in classifying severe and moderate iron deposition at the recommended septal region. However, in patients with low iron indication, different results by the two truncation methods can mislead the investigation of early iron level progression.

COVID-19 and Hemoglobinopathies: A Systematic Review of Clinical Presentations, Investigations, and Outcomes

This systematic review aimed to provide an overview of the clinical profile and outcome of COVID-19 infection in patients with hemoglobinopathy. The rate of COVID-19 mortality and its predictors were also identified. A systematic search was conducted in accordance with PRISMA guidelines in five electronic databases (PubMed, Scopus, Web of Science, Embase, WHO COVID-19 database) for articles published between 1st December 2019 to 31st October 2020. All articles with laboratory-confirmed COVID-19 cases with underlying hemoglobinopathy were included. Methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklists. Thirty-one articles with data on 246 patients with hemoglobinopathy were included in this review. In general, clinical manifestations of COVID-19 infection among patients with hemoglobinopathy were similar to the general population. Vaso-occlusive crisis occurred in 55.6% of sickle cell disease patients with COVID-19 infection. Mortality from COVID-19 infection among patients with hemoglobinopathy was 6.9%. After adjusting for age, gender, types of hemoglobinopathy and oxygen supplementation, respiratory (adj OR = 89.63, 95% CI 2.514-3195.537, p = 0.014) and cardiovascular (adj OR = 35.20, 95% CI 1.291-959.526, p = 0.035) comorbidities were significant predictors of mortality. Patients with hemoglobinopathy had a higher mortality rate from COVID-19 infection compared to the general population. Those with coexisting cardiovascular or respiratory comorbidities require closer monitoring during the course of illness. More data are needed to allow a better understanding on the clinical impact of COVID-19 infections among patients with hemoglobinopathy. Clinical Trial Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020218200.

Reproducibility of liver R2* quantification for liver iron quantification from cardiac R2* acquisitions

OBJECTIVES

To evaluate the reproducibility of liver R2* measurements between a 2D cardiac ECG-gated and a 3D breath-hold liver CSE-MRI acquisition for liver iron quantification.

METHODS

A total of 54 1.5 T MRI exams from 51 subjects (18 women, 36 men, age 35.2 ± 21.8) were included. These included two sub-studies with 23 clinical MRI exams from 19 patients identified retrospectively, 24 participants with known or suspected iron overload, and 7 healthy volunteers acquired prospectively. The 2D cardiac and the 3D liver R2* maps were acquired in the same exam. Either acquisitions were reconstructed using a complex R2* algorithm that accounts for the presence of fat and residual phase errors due to eddy currents. Data were analyzed using colocalized ROIs in the liver.

RESULTS

Linear regression analysis demonstrated high Pearson's correlation and Lin's concordance coefficient for the overall study and both sub-studies. Bland-Altman analysis also showed good agreement, except for a slight increase of the mean R2* value above ~ 400 s^-1. The Kolmogorow-Smirnow test revealed a non-normal distribution for (R2* 3D-R2* 2D) values from 0 to 600 s^-1 in contrast to the 0-200 s^-1 and 0-400 s^-1 subpopulations. Linear regression analysis showed no relevant differences other than the intercept, likely due to only 7 measurements above 400 s^-1.

CONCLUSIONS

The results demonstrate that R2*-measurements in the liver are feasible using 2D cardiac R2* maps compared to 3D liver R2* maps as the reference. Liver R2* may be underestimated for R2* > 400 s^-1 using the 2D cardiac R2* mapping method.

Red cell transfusion and alloimmunization in sickle cell disease

Red cell transfusion remains a critical component of care for acute and chronic complications of sickle cell disease. Randomized clinical trials demonstrated the benefits of transfusion therapy for prevention of primary and secondary strokes and postoperative acute chest syndrome. Transfusion for splenic sequestration, acute chest syndrome, and acute stroke are guided by expert consensus recommendations. Despite overall improvements in blood inventory safety, adverse effects of transfusion are prevalent among patients with sickle cell disease and include alloimmunization, acute and delayed hemolytic transfusion reactions, and iron overload. Judicious use of red cell transfusions, optimization of red cell antigen matching, and the use of erythrocytapheresis and iron chelation can minimize adverse effects. Early recognition and management of hemolytic transfusion reactions can avert poor clinical outcomes. In this review, we discuss transfusion methods, indications, and complications in sickle cell disease with an emphasis on alloimmunization.

Transfusion and Cellular Therapy in Pediatric Sickle Cell Disease

Red blood cell (RBC) transfusion is critical in managing acute and chronic complications of sickle cell disease. Alloimmunization and iron overload remain significant complications of transfusion therapy and are minimized with prophylactic Rh and K antigen RBC matching and iron chelation. Matched sibling donor hematopoietic stem cell transplant (HSCT) is a curative therapeutic option. Autologous hematopoietic stem cell (HSC)-based gene therapy has recently shown great promise, for which obtaining sufficient HSCs is essential for success. This article discusses RBC transfusion indications and complications, transfusion support during HSCT, and HSC mobilization and collection for autologous HSCT with gene therapy.

Kidney iron deposition by R2* is associated with haemolysis and urinary iron

Kidney iron deposition measured by R2* (magnetic resonance imaging) MRI is posited to result from tubular reabsorption of filtered haemoglobin due to intravascular haemolysis. In chronically transfused sickle cell disease (SCD), R2* is elevated and positively correlated with lactate dehydrogenase (LDH). To account for contributions to renal iron from systemic iron overload, we evaluated kidney R2*, urinary iron and haemolysis markers in 62 non-transfused SCD patients. On multivariate analysis, kidney R2* was associated with urinary iron and LDH (R²  = 0·55, P < 0·0001). Our study confirms that kidney R2* is associated with intravascular haemolysis and raises important questions regarding the role of iron in SCD nephropathy.

Hyperferritinemia and acute kidney injury in pediatric patients receiving allogeneic hematopoietic cell transplantation

BACKGROUND

Acute kidney injury (AKI) often occurs in pediatric patients who received allogeneic hematopoietic cell transplantation (HCT). We evaluated the risk and effect of HCT-related AKI in pediatric patients.

METHODS

We retrospectively studied the survival and renal outcome of 69 children 100 days and 1-year posttransplant in our institution in 2004-2016. Stage-3 AKI developed in 34 patients (49%) until 100 days posttransplant.

RESULTS

The 100-day overall survival (OS) rates of patients with stage-3 AKI were lower than those without it (76.5% vs. 94.3%, P = 0.035). The 1-year OS rates did not differ markedly between 21 post-100-day survivors with stage-3 AKI and 29 without it (80.8% vs. 87.9%, P = 0.444). The causes of 19 deaths included the relapse of underlying disease or graft failure (n = 11), treatment-related events (4), and second HCT-related events (4). Underlying disease of malignancy (crude hazard ratio (HR) 5.7; 95% confidence interval (CI), 2.20 to 14.96), > 1000 ng/mL ferritinemia (crude HR 4.29; 95% CI, 2.11 to 8.71), stem cell source of peripheral (crude HR 2.96; 95% CI, 1.22 to 7.20) or cord blood (crude HR 2.29; 95% CI, 1.03 to 5.06), and myeloablative regimen (crude HR 2.56; 95% CI, 1.24 to 5.26), were identified as risk factors for stage-3 AKI until 100 days posttransplant. Hyperferritinemia alone was significant (adjusted HR 5.52; 95% CI, 2.21 to 13.76) on multivariable analyses.

CONCLUSIONS

Hyperferritinemia was associated with stage-3 AKI and early mortality posttransplant. Pretransplant iron control may protect the kidney of pediatric HCT survivors.

Automated exchange compared to manual and simple blood transfusion attenuates rise in ferritin level after 1 year of regular blood transfusion therapy in chronically transfused children with sickle cell disease

BACKGROUND

Optimal strategies for regular blood transfusion therapy are not well defined in sickle cell disease (SCD). This analysis tested the hypothesis that in the first of year of regular transfusions, when chelation therapy use is minimal, automated exchange transfusion would be the superior method for attenuating the rise in ferritin levels compared to simple and manual exchange transfusions.

STUDY DESIGN AND METHODS

The Silent Cerebral Infarct Multi-Center Clinical Trial randomly allocated children with SCD and silent cerebral infarcts to receive standard care or regular transfusions with a target pre-transfusion HbS concentration ≤ 30% and minimum hemoglobin level > 9.0 g/dL. Participants with at least nine transfusions and sufficient ferritin testing in the first year of the trial were included in a planned secondary analysis. Ferritin levels by the end of the first study year were compared between participants receiving automatic exchange transfusion, manual exchange transfusion, and simple transfusion.

RESULTS

A total of 83 participants were analyzed. During the first year of the study, 75.9% of the participants had >80% of transfusions via one transfusion method. At baseline no significant differences in ferritin levels were observed in the three transfusion groups (p = 0.1). After 1 year of transfusions the median (interquartile range) ferritin levels in the simple transfusion (n = 40), manual exchange transfusion (n = 34) and automatic exchange transfusion (n = 9) groups were 1800 ng/mL (1426-2204 ng/mL), 1530 ng/mL (1205-1805 ng/mL), and 355 ng/mL (179-579 ng/mL), respectively (p < 0.001).

CONCLUSION

Automated exchange transfusion, when compared to other transfusion methods, is the optimal transfusion strategy for attenuating increase in ferritin levels in children with SCD.

Cardiomyopathy in Sickle Cell Disease

Sickle cell disease (SCD) is an inherited disorder that occurs due to point mutation in the beta-globin chain resulting in the production of hemoglobin S that tends to become rigid and sickle-shaped under low oxygen concentration. These sickle-shaped red blood cells (RBCs) obstruct the blood vessels leading to reduced blood flow to the organs, causing ischemia and tissue fibrosis. These sickle RBCs being abnormal in shape are frequently sequestered by the spleen, creating a state of chronic anemia in the body. This chronic anemia leads to a high cardiac output state causing cardiac remodeling. To tackle chronic anemia, patients are frequently treated with blood transfusions that makes them more prone to the risk of iron overload (from newly transfused RBCs and iron release from the RBCs that just got sequestered as well as from volume overload) and volume overload causing left ventricular (LV) dilation. The above-mentioned mechanism of cardiac hypertrophy, along with LV dilation together, makes SCD-related cardiomyopathy unique cardiomyopathy with features of restrictive cardiomyopathy with LV dilation. It is interesting to note here that even though there is a presence of LV dilatation, Systolic dysfunction is very uncommon in SCD-related cardiomyopathy.

Blood utilization and characteristics of patients treated with chronic transfusion therapy in a large cohort of Brazilian patients with sickle cell disease

BACKGROUND

Red blood cell (RBC) transfusions are used in sickle cell disease (SCD) to treat acute complications or as chronic transfusion therapy (CTT) to prevent severe manifestations. The objectives of this study were to describe blood utilization and adverse events (AEs) associated with RBCs in the Brazilian SCD population and compare characteristics of patients treated or not with CTT.

STUDY DESIGN AND METHODS

A SCD cohort was established at six Brazilian centers. Medical and blood bank records were abstracted for clinical and transfusion history. Two controls not treated with CTT matched on center, SCD genotype, sex, and age were selected for each CTT case within the cohort to compare characteristics between the two groups.

RESULTS

Most of the 2794-member cohort had received a transfusion (75.0% of children and 89.2% of adults) with 29.2% of patients receiving transfusion in the prior year. There were 170 (10.6%) children and 115 (9.2%) adults treated with CTT. Children not treated with CTT were more likely to have pain and acute chest hospitalizations in the prior year (25.3% vs. 11.9%, p = 0.0003; and 22.0% vs. 10.7%, p = 0.002, respectively). Both iron overload and alloimmunization were more common in CTT cases compared to controls (65.6% vs. 17.0% and 36.2% vs. 15.9%, respectively). A higher proportion of adults treated with CTT demonstrated oxygen saturation of greater than 95% compared to controls not treated (51.1% vs. 39.2%), while there was no difference in oxygenation between children treated or not. Of 4501 transfusion episodes, 28 (0.62%) AEs were reported. There was no difference in AEs associated with transfusions for acute indications versus CTT.

CONCLUSION

Red blood cell transfusion was common in Brazilian SCD patients, with utilization driven by CTT. Transfusion reactions were not common; however, alloimmunization and iron overload were frequent among those on CTT, highlighting the need for novel clinical strategies to mitigate these risks.

Cardiovascular complications of sickle cell disease

Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, and a global health problem. Pathological features of the abnormal hemoglobin (HbS) result in 2 hallmarks of the disease - recurrent episodes of acute microvascular occlusion and chronic hemolytic anemia - that inflict continuous and insidious damage to multiple organs. With improved childhood survival, SCD in adults has evolved into a chronic degenerative disease with underlying damage to multiple organs including the heart and lungs. Cardiopulmonary complications, including cardiomyopathy, diastolic dysfunction, pulmonary hypertension (PH), and sudden cardiac death are the most common causes of morbidity and mortality. Awareness of the sickle-related cardiovascular phenotypes is important for screening, early diagnosis, and intervention of cardiac complications in this disorder.

American Society of Hematology 2020 guidelines for sickle cell disease: transfusion support

BACKGROUND

Red cell transfusions remain a mainstay of therapy for patients with sickle cell disease (SCD), but pose significant clinical challenges. Guidance for specific indications and administration of transfusion, as well as screening, prevention, and management of alloimmunization, delayed hemolytic transfusion reactions (DHTRs), and iron overload may improve outcomes.

OBJECTIVE

Our objective was to develop evidence-based guidelines to support patients, clinicians, and other healthcare professionals in their decisions about transfusion support for SCD and the management of transfusion-related complications.

METHODS

The American Society of Hematology formed a multidisciplinary panel that was balanced to minimize bias from conflicts of interest and that included a patient representative. The panel prioritized clinical questions and outcomes. The Mayo Clinic Evidence-Based Practice Research Program supported the guideline development process. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to form recommendations, which were subject to public comment.

RESULTS

The panel developed 10 recommendations focused on red cell antigen typing and matching, indications, and mode of administration (simple vs red cell exchange), as well as screening, prevention, and management of alloimmunization, DHTRs, and iron overload.

CONCLUSIONS

The majority of panel recommendations were conditional due to the paucity of direct, high-certainty evidence for outcomes of interest. Research priorities were identified, including prospective studies to understand the role of serologic vs genotypic red cell matching, the mechanism of HTRs resulting from specific alloantigens to inform therapy, the role and timing of regular transfusions during pregnancy for women, and the optimal treatment of transfusional iron overload in SCD.

Cardiac T2 * mapping: Techniques and clinical applications

Cardiac T₂* mapping is a noninvasive MRI method that is used to identify myocardial iron accumulation in several iron storage diseases such as hereditary hemochromatosis, sickle cell disease, and β‐thalassemia major. The method has improved over the years in terms of MR acquisition, focus on relative artifact‐free myocardium regions, and T₂* quantification. Several improvement factors involved include blood pool signal suppression, the reproducibility of T₂* measurement as affected by scanner hardware, and acquisition software. Regarding the T₂* quantification, improvement factors include the applied curve‐fitting method with or without truncation of the signals acquired at longer echo times and whether or not T₂* measurement focuses on multiple segmental regions or the midventricular septum only. Although already widely applied in clinical practice, data processing still differs between centers, contributing to measurement outcome variations. State of the art T₂* measurement involves pixelwise quantification providing better spatial iron loading information than region of interest‐based quantification. Improvements have been proposed, such as on MR acquisition for free‐breathing mapping, the generation of fast mapping, noise reduction, automatic myocardial contour delineation, and different T₂* quantification methods. This review deals with the pro and cons of different methods used to quantify T₂* and generate T₂* maps. The purpose is to recommend a combination of MR acquisition and T₂* mapping quantification techniques for reliable outcomes in measuring and follow‐up of myocardial iron overload. The clinical application of cardiac T₂* mapping for iron overload's early detection, monitoring, and treatment is addressed. The prospects of T₂* mapping combined with different MR acquisition methods, such as cardiac T₁ mapping, are also described.

Level of Evidence: 4

Technical Efficacy Stage: 5

J. Magn. Reson. Imaging 2019.

Can molecular markers of oxygen homeostasis and the measurement of tissue oxygen be leveraged to optimize red blood cell transfusions?

PURPOSE OF REVIEW

The clinical indication for transfusing red blood cells (RBCs) is to restore or maintain adequate oxygenation of respiring tissue. Oxygen (O2) transport, delivery, and utilization following transfusion are impacted by perfusion, hemoglobin (Hb) allosteric saturation/desaturation, and the concentration of tissue O2. Bioavailable O2 maintains tissue utilization and homeostasis; therefore, measuring imbalances in supply and demand could be valuable to assessing blood quality and transfusion effectiveness. O2 homeostasis is critically intertwined with erythropoietic response in blood loss and anemia and the hormones that modulate iron mobilization and RBC production (e.g., erythropoietin, erythroferrone, and hepcidin) are intriguing markers for the monitoring of transfusion effectiveness in acute and chronic settings. The evaluation of RBC donor unit quality and the determination of RBC transfusion needs are emerging areas for biomarker development and minimally invasive O2 measurements.

RECENT FINDINGS

Novel methods for assessing circulatory and tissue compartment biomarkers of transfusion effectiveness are suggested. In addition, monitoring of tissue oxygenation by indirect and direct measurements of O2 is available and applied in experimental settings.

SUMMARY

Herein, we discuss tissue O2 homeostasis, related aspects of erythropoiesis, molecular markers and measurements of tissue oxygenation, all aimed at optimizing transfusion and assessing blood quality.

Myocardial Iron Overload in Sickle Cell Disease: A Rare But Potentially Fatal Complication of Transfusion

Sickle cell disease (SCD) is a frequent indication for chronic transfusion, which can cause iron overload. Excess iron often affects the liver, but not the heart in SCD. Magnetic resonance (MR) is recommended to detect myocardial iron overload (MIO) but its elevated cost requires optimized indication. We aimed to compile all published data on MIO in SCD upon the description of a fatal case of severe MIO in our institution, and to determine associated risk factors. We performed a systematic review using the PRISMA guidelines in two databases (PubMed and Web of Science). Inclusion criteria were publication in English, patients diagnosed with SCD, and reporting ferritin and MIO by MR. Twenty publications reported on 865 SCD adult and pediatric patients, with at least 10 other cases of MIO. The prevalence of MIO in chronically transfused SCD patients can be estimated to be 3% or less, and is associated with high transfusion burden, top-up transfusions, and low adherence to iron chelation. Cardiac siderosis in SCD is rarely reported, and increased awareness with better use of the available screening tools are necessary. Prospective studies should define the recommended chelation regimens depending on the severity of MIO.

Recommendations for the use of red blood cell exchange in sickle cell disease

Sickle cell disease (SCD) is a genetic disorder characterised by a single mutation of the beta globin gene, causing the production of an abnormal haemoglobin called sickle haemoglobin (HbS). In its deoxygenated form, HbS polymerises, causing major rheological disorders, which presents clinically as periodic vaso-occlusive crises, chronic haemolysis and chronic vascular dysfunction. Patients often resort to a background treatment, and transfusion remains the cornerstone in the management of the disease, significantly reducing morbidity and mortality. The aim of red blood cell exchange (RBCX) is to improve tissue oxygenation by increasing haemoglobin levels while lowering HbS levels. RBCX can be performed by manual or automated exchange, and each technique has its own set of advantages and disadvantages. This article will outline the transfusion indications for the main complications of SCD, as well as the most appropriate strategy to use.

Interaction of Transfusion and Iron Chelation in Thalassemias

The relationship between blood transfusion intensity, chelatable iron pools, and extrahepatic iron distribution is described in thalassemia. Risk factors for cardiosiderosis are discussed with particular reference to the balance of transfusional iron loading rate and transferrin-iron utilization rate as marked by plasma levels of soluble transferrin receptors. Low transfusion regimens increase residual erythropoiesis allowing for apotransferrin-dependent clearance of non-transferrin-bound iron species otherwise destined for myocardium. The impact of transfusion rates on chelation dosing required for iron balance is also shown.

Measuring liver T2* and cardiac T2* in a single acquisition

PURPOSE

The purpose of this study is determine if both liver T2* and cardiac T2* can be measured on a single breath-hold acquisition.

MATERIALS AND METHODS

For this IRB-approved retrospective study, 137 patients with dedicated Cardiac MRI and Liver MRI examinations obtained sequentially on 1.5T scanners and on the same day were included for analysis. Both the cardiac and liver MRI examinations utilized GRE sequences for quantification of tissue iron. Specifically, T2* was measured using an 8-echo, multi-echo gradient echo single breath-hold sequence. Liver T2* was measured in a blinded manner on images from each of the cardiac and dedicated liver MRI examinations and were correlated. Bland-Altman difference plot was used to assess mean bias.

RESULTS

137 examinations from 93 subjects met inclusion criteria. 10 examination pairs were excluded because the first echo time (TE) on the cardiac MRI was insufficiently short for the very high liver iron content. After exclusion, 127 studies from 89 subjects (67.4% males) were included in the final analysis. The mean subject age (± standard deviation) was 11.5 ± 7.5 years (range 0-29.3 years; median 10.5 years). Mean liver T2* measured on cardiac MRI was 8.3 ± 7.7 ms and mean liver T2* measured on dedicated liver MRI was 7.8 ± 7.4 ms (p < 0.001). There was strong positive correlation between the two liver T2* measurements (r = 0.989, p < 0.0001; 95% CI 0.985-0.992). With the exception of borderline outliers, all values fell within two standard deviations on the Bland-Altman difference plots, with a mean bias of 0.5 ms (range - 1.8 to + 2.7 ms).

CONCLUSION

In most patients with suspected or known iron overload, a single breath-hold GRE sequence may be sufficient to evaluate the iron concentration (T2*) of both the myocardium and the liver.

Estimation of pancreatic R2* for iron overload assessment in the presence of fat: a comparison of different approaches

OBJECTIVES

To propose a method for estimating pancreatic relaxation rate, R2*, from conventional multi-echo MRI, based on the nonlinear fitting of the acquired magnitude signal decay to MR signal models that take into account both the signal oscillations induced by fat and the different R2* values of pancreatic parenchyma and fat.

MATERIALS AND METHODS

Single-peak fat (SPF) and multi-peak fat (MPF) models were introduced. Single-R2* and dual-R2* assumptions were considered as well. Analyses were conducted on simulated data and 20 thalassemia major patients.

RESULTS

Simulations revealed the ability of the MPF model to correctly estimate the R2* value in a large range of fat fractions and R2* values. From the comparison between the results obtained with a single R2* value for water and fat and the dual-R2* approach, the latter is more accurate in both water R2* and fat fraction estimation. In patient's data analysis, a strong concordance was found between SPF and MPF estimated data with measurements done with manual signal correction and from fat-saturated images. The MPF method showed better reproducibility.

CONCLUSION

The MPF dual-R2* approach improves reproducibility and reduces image analysis time in the assessment of pancreatic R2* value in patients with iron overload.

The effect of iron chelation therapy on overall survival in sickle cell disease and β-thalassemia: A systematic review

Red blood cell transfusions have become standard of care for the prevention of life-threatening anemia in patients with β-thalassemia and sickle cell disease (SCD). However, frequent transfusions can lead to accumulation of iron that can result in liver cirrhosis, diabetes mellitus, arthritis, arrhythmias, cardiomyopathy, heart failure, and hypogonadotropic hypogonadism. Iron chelation therapy has been shown to reduce serum ferritin levels and liver iron content, but limitations of trial design have prevented any demonstration of improved survival. The objective of this systematic review was to investigate the impact of iron chelation therapy on overall and event-free survival in patients with β-thalassemia and SCD. Eighteen articles discussing survival in β-thalassemia and 3 in SCD were identified. Overall iron chelation therapy resulted in better overall survival, especially if it is instituted early and compliance is maintained. Comparative studies did not show any significant differences between available iron chelation agents, although there is evidence that deferiprone is better tolerated than deferoxamine and that compliance is more readily maintained with the newer oral drugs, deferiprone and deferasirox. Iron chelation therapy, particularly the second-generation oral agents, appears to be associated with improved overall and event-free survival in transfusion-dependent patients with β-thalassemia and patients with SCD.

The correlation between cardiac magnetic resonance T2* and left ventricular global longitudinal strain in people with β-thalassemia

BACKGROUND

Heart failure is the biggest cause of mortality and morbidity in people with thalassemia, and iron deposition in cardiac tissue impairs cardiovascular function. Therefore, early detection of cardiac involvement is important to improve the prognosis in these individuals.

METHOD

Two- and three-dimensional echocardiography was performed to evaluate left ventricular ejection fraction (LVEF), left ventricular volumes and diameters, and global longitudinal strain (GLS) in 130 individuals with β-thalassemia using the speckle tracking method. Magnetic resonance imaging (MRI) was carried out on both the heart and liver. The participants were divided into 2 groups based on cardiac T2* values (normal and abnormal cardiac iron load), and the correlation between cardiac T2* MRI and GLS was evaluated.

RESULTS

The statistical analysis showed a significant correlation between cardiac T2* MRI and left ventricular global longitudinal strain. There was a significant difference in global longitudinal strain (P < .0001), liver MRI T2*( P < .0001), and left ventricular ejection fraction (P < .001) between the 2 groups. The optimal cutoff value for GLS was -18.5% with sensitivity and specificity 73.0% and 63.0%, respectively (postitive predictive value = 50%, negative predictive value = 82.3%, AUC = 0.742, std. error = 0.046) which predicts T2* value of <20 ms, according to cardiac MRI.

CONCLUSIONS

The participants with cardiac iron overload had a lower GLS than those without one. This suggests that GLS may be a useful method to predict myocardial iron overload particularly in β-thalassemia patients with subclinical cardiac involvement.

Applications of cardiac magnetic resonance imaging in sickle cell disease

Cardiac magnetic resonance imaging (CMR) has evolved from an effective research tool to a non-invasive clinical modality with versatile applications. The accuracy of volume measurements and functional assessment and the ability to identify unique myocardial tissue characteristics non-invasively are the primary advantages of CMR. The use of CMR in sickle cell disease (SCD) has been limited clinically to myocardial iron assessment. The use of other CMR applications to characterize the cardiac pathology in SCD is slowly emerging but remains limited to research level. In this review, we discuss some of the applications of CMR in studying cardiovascular diseases and its potential uses in SCD for research and clinical purposes.

Prevalence and predictors of cardiac and liver iron overload in patients with thalassemia: A multicenter study based on real-world data

Prevalence of cardiac and liver iron overload in patients with thalassemia in real-world practice may vary among different regions especially in the era of widely-used iron chelation therapy. The aim of this study was to determine the prevalence of cardiac and liver iron overload in and the management patterns of patients with thalassemia in real-world practice in Thailand. We established a multicenter registry for patients with thalassemia who underwent magnetic resonance imaging (MRI) as part of their clinical evaluation. All enrolled patients underwent cardiac and liver MRI for assessment of iron overload. There were a total of 405 patients enrolled in this study. The mean age of patients was 18.8±12.5years and 46.7% were male. Two hundred ninety-six (73.1%) of patients received regular blood transfusion. Prevalence of cardiac iron overload (CIO) and liver iron overload (LIO) was 5.2% and 56.8%, respectively. Independent predictors for iron overload from laboratory information were serum ferritin and transaminase for both CIO and LIO. Serum ferritin can be used as a screening tool to rule-out CIO and to diagnose LIO. Iron chelation therapy was given in 74.6%; 15.3% as a combination therapy.

The hepatocyte-specific HNF4α/miR-122 pathway contributes to iron overload-mediated hepatic inflammation

Hepatic iron overload (IO) is a major complication of transfusional therapy. It was generally thought that IO triggers substantial inflammatory responses by producing reactive oxygen species in hepatic macrophages. Recently, a decrease in microRNA-122 (miR-122) expression was observed in a genetic knockout (Hfe^-/-) mouse model of IO. Because hepatocyte-enriched miR-122 is a key regulator of multiple hepatic pathways, including inflammation, it is of interest whether hepatocyte directly contributes to IO-mediated hepatic inflammation. Here, we report that IO induced similar inflammatory responses in human primary hepatocytes and Thp-1-derived macrophages. In the mouse liver, IO resulted in altered expression of not only inflammatory genes but also >230 genes that are known targets of miR-122. In addition, both iron-dextran injection and a 3% carbonyl iron-containing diet led to upregulation of hepatic inflammation, which was associated with a significant reduction in HNF4α expression and its downstream target, miR-122. Interestingly, the same signaling pathway was changed in macrophage-deficient mice, suggesting that macrophages are not the only target of IO. Most importantly, hepatocyte-specific overexpression of miR-122 rescued IO-mediated hepatic inflammation. Our findings indicate the direct involvement of hepatocytes in IO-induced hepatic inflammation and are informative for developing new molecular targets and preventative therapies for patients with major hemoglobinopathy.

Residual erythropoiesis protects against myocardial hemosiderosis in transfusion-dependent thalassemia by lowering labile plasma iron via transient generation of apotransferrin

Cardiosiderosis is a leading cause of mortality in transfusion-dependent thalassemias. Plasma non-transferrin-bound iron and its redox-active component, labile plasma iron, are key sources of iron loading in cardiosiderosis. Risk factors were identified in 73 patients with or without cardiosiderosis. Soluble transferrin receptor-1 levels were significantly lower in patients with cardiosiderosis (odds ratio 21). This risk increased when transfusion-iron loading rates exceeded the erythroid transferrin uptake rate (derived from soluble transferrin receptor-1) by >0.21 mg/kg/day (odds ratio 48). Labile plasma iron was >3-fold higher when this uptake rate threshold was exceeded, but non-transferrin-bound iron and transferrin saturation were comparable. The risk of cardiosiderosis was decreased in patients with low liver iron, ferritin and labile plasma iron, or high bilirubin, reticulocyte counts or hepcidin. We hypothesized that high erythroid transferrin uptake rate decreases cardiosiderosis through increased erythroid re-generation of apotransferrin. To test this, iron uptake and intracellular reactive oxygen species were examined in HL-1 cardiomyocytes under conditions modeling transferrin effects on non-transferrin-bound iron speciation with ferric citrate. Intracellular iron and reactive oxygen species increased with ferric citrate concentrations especially when iron-to-citrate ratios exceeded 1:100, i.e. conditions favoring kinetically labile monoferric rather than oligomer species. Excess iron-binding equivalents of apotransferrin inhibited iron uptake and decreased both intracellular reactive oxygen species and labile plasma iron under conditions favoring monoferric species. In conclusion, high transferrin iron utilization, relative to the transfusion-iron load rate, decreases the risk of cardiosiderosis. A putative mechanism is the transient re-generation of apotransferrin by an active erythron, rapidly binding labile plasma iron-detectable ferric monocitrate species.

How we manage iron overload in sickle cell patients

Blood transfusion plays a prominent role in the management of patients with sickle cell disease (SCD), but causes significant iron overload. As transfusions are used to treat the severe complications of SCD, it remains difficult to distinguish whether organ damage is a consequence of iron overload or is due to the complications treated by transfusion. Better management has resulted in increased survival, but prolonged exposure to iron puts SCD patients at greater risk for iron-related complications that should be treated. The success of chelation therapy is dominated by patient adherence to prescribed treatment; thus, adjustment of drug regimens to increase adherence to treatment is critical. This review will discuss the current biology of iron homeostasis in patients with SCD and how this informs our clinical approach to treatment. We will present the clinical approach to treatment of iron overload at our centre using serial assessment of organ iron by magnetic resonance imaging.

Cardiac iron overload in chronically transfused patients with thalassemia, sickle cell anemia, or myelodysplastic syndrome

The risk and clinical significance of cardiac iron overload due to chronic transfusion varies with the underlying disease. Cardiac iron overload shortens the life expectancy of patients with thalassemia, whereas its effect is unclear in those with myelodysplastic syndromes (MDS). In patients with sickle cell anemia (SCA), iron does not seem to deposit quickly in the heart. Our primary objective was to assess through a multicentric study the prevalence of cardiac iron overload, defined as a cardiovascular magnetic resonance T2*<20 ms, in patients with thalassemia, SCA, or MDS. Patient inclusion criteria were an accurate record of erythrocyte concentrates (ECs) received, a transfusion history >8 ECs in the past year, and age older than 6 years. We included from 9 centers 20 patients with thalassemia, 41 with SCA, and 25 with MDS in 2012-2014. Erythrocytapharesis did not consistently prevent iron overload in patients with SCA. Cardiac iron overload was found in 3 (15%) patients with thalassemia, none with SCA, and 4 (16%) with MDS. The liver iron content (LIC) ranged from 10.4 to 15.2 mg/g dry weight, with no significant differences across groups (P = 0.29). Abnormal T2* was not significantly associated with any of the measures of transfusion or chelation. Ferritin levels showed a strong association with LIC. Non-transferrin-bound iron was high in the thalassemia and MDS groups but low in the SCA group (P<0.001). Hepcidin was low in thalassemia, normal in SCA, and markedly elevated in MDS (P<0.001). Two mechanisms may explain that iron deposition largely spares the heart in SCA: the high level of erythropoiesis recycles the iron and the chronic inflammation retains iron within the macrophages. Thalassemia, in contrast, is characterized by inefficient erythropoiesis, unable to handle free iron. Iron accumulation varies widely in MDS syndromes due to the competing influences of abnormal erythropoiesis, excess iron supply, and inflammation.

Severe cardiac iron toxicity in two adults with sickle cell disease

BACKGROUND

Use of chronic blood transfusions as a treatment modality in patients with blood disorders places them at risk for iron overload. Since patients with β-thalassemia major (TM) are transfusion-dependent, most studies on iron overload and chelation have been conducted in this population. While available data suggest that compared to TM, patients with sickle cell disease (SCD) have a lower risk of extrahepatic iron overload, significant iron overload can develop. Further, previous studies have demonstrated a direct relationship between iron overload and morbidity and mortality rates in SCD. However, reports describing the outcome for patients with SCD and cardiac iron overload are rare.

STUDY DESIGN AND METHODS

We performed a retrospective analysis and identified two SCD patients with cardiac iron overload. We provide detailed descriptions of both cases and their outcomes.

RESULTS

Serum ferritin levels ranged between 17,000 and 19,000 μg/L. Both had liver iron concentrations in excess of 35 mg of iron per gram of dried tissue as well as evidence of cardiac iron deposition on magnetic resonance imaging. One patient died of an arrhythmia and had evidence of severe multiorgan iron overload via autopsy. On the other hand, after appropriate therapy, a second patient had improvement in cardiac function.

CONCLUSION

Improper treatment of iron overload in SCD can lead to a fatal outcome. Alternatively, iron overload may potentially be prevented or reversed with judicious use of blood transfusions and early use of chelation therapy, respectively.

Semi-automated myocardial segmentation of bright blood multi-gradient echo images improves reproducibility of myocardial contours and T2* determination

Objectives

Early detection of iron loading is affected by the reproducibility of myocardial contour assessment. A novel semi-automatic myocardial segmentation method is presented on contrast-optimized composite images and compared to the results of manual drawing.

Materials and methods

Fifty-one short-axis slices at basal, mid-ventricular and apical locations from 17 patients were acquired by bright blood multi-gradient echo MRI. Four observers produced semi-automatic and manual myocardial contours on contrast-optimized composite images. The semi-automatic segmentation method relies on vector field convolution active contours to generate the endocardial contour. After creating radial pixel clusters on the myocardial wall, a combination of pixel-wise coefficient of variance (CoV) assessment and k-means clustering establishes the epicardial contour for each segment.

Results

Compared to manual drawing, semi-automatic myocardial segmentation lowers the variability of T2* quantification within and between observers (CoV of 12.05 vs. 13.86% and 14.43 vs. 16.01%) by improving contour reproducibility (P < 0.001). In the presence of iron loading, semi-automatic segmentation also lowers the T2* variability within and between observers (CoV of 13.14 vs. 15.19% and 15.91 vs. 17.28%).

Conclusion

Application of semi-automatic myocardial segmentation on contrast-optimized composite images improves the reproducibility of T2* quantification.

Iron mediated toxicity and programmed cell death: A review and a re-examination of existing paradigms

Iron is an essential micronutrient that is problematic for biological systems since it is toxic as it generates free radicals by interconverting between ferrous (Fe²⁺) and ferric (Fe³⁺) forms. Additionally, even though iron is abundant, it is largely insoluble so cells must treat biologically available iron as a valuable commodity. Thus elaborate mechanisms have evolved to absorb, re-cycle and store iron while minimizing toxicity. Focusing on rarely encountered situations, most of the existing literature suggests that iron toxicity is common. A more nuanced examination clearly demonstrates that existing regulatory processes are more than adequate to limit the toxicity of iron even in response to iron overload. Only under pathological or artificially harsh situations of exposure to excess iron does it become problematic. Here we review iron metabolism and its toxicity as well as the literature demonstrating that intracellular iron is not toxic but a stress responsive programmed cell death-inducing second messenger.

Longitudinal MRI and Ferritin Monitoring of Iron Overload in Chronically Transfused and Chelated Children With Sickle Cell Anemia and Thalassemia Major

Iron overload is an ineluctable complication in chronically transfused children warranting accurate assessment to avoid related morbidity. We investigated longitudinally the relationships between ferritin levels and hepatic and cardiac T2* magnetic resonance imaging (MRI) in a cohort of chronically transfused children receiving chelation therapy. Thirty children with sickle cell anemia (SCA) and 7 with thalassemia major (TM) chelated similarly by deferasirox were analyzed. Sex ratio, age, median duration of transfusion programs (5 y; range, 2 to 14 y), median transfusion iron intake 0.54 mg/kg/d (range, 0.27 to 0.74 mg/kg/d), and median ferritin level (1550 mg/L; range, 184 to 6204 mg/L) were comparable in TM and SCA. A significant relation was found between ferritin level and transfusion iron intake (P<0.001) despite chelation therapy. Analysis of 73 hepatic T2* MRI performed yearly demonstrated severe hepatic iron overload (≥14 mg/g) in 38.3% cases and a strong relationship between serum ferritin level and liver iron content both in SCA and TM (P<0.001). Analysis of 55 cardiac T2* MRI measurements found no cardiac overload in patients with SCA. Cardiac iron overload was moderate in 4 cases and severe in 1 case of TM. In almost half the cases, ferritin trend correctly predicted hepatic iron trend, both in patients with SCA and TM but failed to predict cardiac iron trend, notably in TM patients. Despite chelation therapy, iron burden in chronically transfused patients remains a threat. Ferritin levels are associated with liver iron overload in chelated children with SCA and TM, but iron burden should be best monitored with MRI whenever the setting allows it.