An update on recent studies of extracellular vesicles and their role in hypercoagulability in thalassemia (Review)

Thromboembolic events are a significant clinical concern in thalassemia and hemoglobinopathies, highlighting the need for new strategies to treat and detect these specific hematologic complications. In recent years, extracellular vesicles (EVs) have garnered interest due to their role in cell-to-cell communication, including angiogenesis, immune responses and coagulation activation. Their multifaceted role depends on the cellular origin and cargo, making them potential diagnostic biomarkers and therapeutic agents. The present review highlights recent advances in understanding the involvement of EVs in hypercoagulability in thalassemia, the characterization of circulating EVs and the potential for using EVs as predictive biomarkers. β-Thalassemia intermedia exhibits a high incidence of thromboembolic events, contributing to significant morbidity and mortality. Advanced technologies have enabled the profiling and characterization of circulating EVs in patients with β-thalassemia through various techniques, including flow cytometry, proteomic studies, reverse transcription-quantitative PCR, transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. Microparticles from splenectomized β-thalassemia/hemoglobin E patients induce platelet activation and aggregation, potentially contributing to thrombus formation. The abundance of these microparticles, primarily released from platelets and damaged red cells, may have a role in thromboembolic events and other clinical complications in thalassemia. This suggests a promising future for EVs as diagnostic and predictive biomarkers in thalassemia management.

Evaluating von Willebrand factor and ADAMTS13 levels in thalassemia major patients and assessing a possible association with Thrombospondin-1

INTRODUCTION

Alterations in the endothelium and endothelial adhesion proteins such as von Willebrand factor (vWF) play major roles in hypercoagulability in thalassemia. vWF protein release leads to platelet aggregation and thrombi formation at the site of vascular injury. It is then degraded by the proteolytic enzyme ADAMTS13. Thrombospondin-1 is a multifactorial glycoprotein, which was reported to compete with ADAMTS13 for sites of vWF proteolysis. In this study, levels of vWF, ADAMTS13, and TSP-1 proteins were determined in β-thalassemia major patients. A possible association between TSP-1 and vWF and ADAMTS-13 was also evaluated.

METHODS

The study was conducted on 80 β-thalassemia major patients and 80 age and sex matched healthy controls. The 80 patients were sub-divided into two groups; splenectomised and non-splenectomised. vWF, ADAMTS13 and TSP-1 plasma level were measured using ELISA technique.

RESULTS

There was no significant difference in vWF and TSP-1 levels between patients and controls (p > 0.05). However, ADAMTS13 levels and ADAMTS13 activity/vWF antigen ratio were significantly higher in patients compared to controls (p < 0.05). VWF antigen and TSP-1 level were significantly higher in splenectomised patients (p = 0.025 and p < 0.001, respectively). We also observed a significant decrease in ADAMTS13 activity/vWF antigen ratio among splenectomised compared to non- splenectomised patients (p = 0.019). Correlation analysis showed a significant negative correlation between TSP-1 and vWF Collagen Binding Activity (r = -0.394, p = 0.021) and a positive correlation with ADAMTS13 activity/vWF antigen ratio (r = 0.356, p = 0.039) in splenectomised compared to non- splenectomised patients.

CONCLUSION

Our findings highlight the adequacy of patient management protocols for β-TM in Kuwait as patients presented with comparable levels of platelets, vWF and TSP-1 compared to normal controls. The reported increase in ADAMTS13 in patients may be required to maintain normal levels of vWF. Although no active thrombotic episodes were reported at the time of the study, the significant rise in platelets, vWF:Ag and TSP-1 levels in splenectomised patients may indicate a tendency towards hypercoagulability. Monitoring of splenectomised patients is recommended.

Accelerated atherosclerosis in beta-thalassemia

Children with beta-thalassemia (BT) present with an increase in carotid intima-medial thickness, an early sign suggestive of premature atherosclerosis. However, it is unknown if there is a direct relationship between BT and atherosclerotic disease. To evaluate this, wild-type (WT, littermates) and BT (Hbbth3/+) mice, both male and female, were placed on a 3-mo high-fat diet with low-density lipoprotein receptor suppression via overexpression of proprotein convertase subtilisin/kexin type 9 (PCSK9) gain-of-function mutation (D377Y). Mechanistically, we hypothesize that heme-mediated oxidative stress creates a proatherogenic environment in BT because BT is a hemolytic anemia that has increased free heme and exhausted hemopexin, heme's endogenous scavenger, in the vasculature. We evaluated the effect of hemopexin (HPX) therapy, mediated via an adeno-associated virus, to the progression of atherosclerosis in BT and a phenylhydrazine-induced model of intravascular hemolysis. In addition, we evaluated the effect of deferiprone (DFP)-mediated iron chelation in the progression of atherosclerosis in BT mice. Aortic en face and aortic root lesion area analysis revealed elevated plaque accumulation in both male and female BT mice compared with WT mice. Hemopexin therapy was able to decrease plaque accumulation in both BT mice and mice on our phenylhydrazine (PHZ)-induced model of hemolysis. DFP decreased atherosclerosis in BT mice but did not provide an additive benefit to HPX therapy. Our data demonstrate for the first time that the underlying pathophysiology of BT leads to accelerated atherosclerosis and shows that heme contributes to atherosclerotic plaque development in BT.NEW & NOTEWORTHY This work definitively shows for the first time that beta-thalassemia leads to accelerated atherosclerosis. We demonstrated that intravascular hemolysis is a prominent feature in beta-thalassemia and the resulting increases in free heme are mechanistically relevant. Adeno-associated virus (AAV)-hemopexin therapy led to decreased free heme and atherosclerotic plaque area in both beta-thalassemia and phenylhydrazine-treated mice. Deferiprone-mediated iron chelation led to deceased plaque accumulation in beta-thalassemia mice but provided no additive benefit to hemopexin therapy.

Cardiovascular Complications in β-Thalassemia: Getting to the Heart of It

Beta thalassemia is an inherited disorder resulting in abnormal or decreased production of hemoglobin, leading to hemolysis and chronic anemia. The long-term complications can affect multiple organ systems, namely the liver, heart, and endocrine. Myocardial iron overload is a common finding in β-thalassemia. As a result, different cardiovascular complications in the form of cardiomyopathy, pulmonary hypertension, arrhythmias, and vasculopathies can occur, and in extreme cases, sudden cardiac death. Each of these complications pertains to underlying etiologies and risk factors, which highlights the importance of early diagnosis and prevention. In this review, we will discuss different types of cardiovascular complications that can manifest in patients with β-thalassemia, in addition to the current diagnostic modalities, preventive and treatment modalities for these complications.

Endothelin-1 gene polymorphism (G8002A) and endothelial monocyte-activating polypeptide II: Role in vascular dysfunction in pediatric patients with β-thalassemia major

BACKGROUND

Endothelin-1 (ET-1), a potent endogenous vasoconstrictor, stimulates production of reactive oxygen species. Endothelial monocyte-activating polypeptide-II (EMAP-II) is a multifunctional polypeptide.

AIM

To assess ET-1 gene polymorphism (G8002A) in pediatric patients with β-thalassemia major (β-TM) as a potential genetic marker for vascular dysfunction and its possible relation to EMAP II, oxidative stress and vascular complications.

METHODS

β-TM patients (n = 95) without symptomatic cardiac or renal disease were compared with 95 healthy controls. Markers of hemolysis, serum ferritin, urinary albumin-to-creatinine ratio, serum EMAP II, malondialdehyde (MDA) and antioxidant enzymes; superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH), glutathione reductase and catalase were measured. ET-1 gene polymorphism (G8002A) was determined using polymerase chain reaction‑restriction fragment length polymorphism.

RESULTS

β-TM patients had significantly higher EMAP II than healthy controls. EMAP II was significantly higher among patients with cardiac disease, pulmonary hypertension (PH) risk, nephropathy, poor compliance to therapy and ferritin ≥ 2500 μg/L. There were significant correlations between EMAP II and transfusion index, LDH, ferritin and oxidative stress markers. The AA genotype of ET-1 gene polymorphism (G8002A) was significantly higher among β-TM patients than controls. The number of patients with cardiac disease, PH risk or nephropathy was significantly higher among AA genotype compared with GG and GA genotypes. Lactate dehydrogenase (LDH), serum ferritin, EMAP II, MDA, SOD and GPx were significantly higher in AA genotype.

CONCLUSION

ET-1 gene polymorphism (G8002A) could be a possible genetic marker for prediction of increased susceptibility to cardiopulmonary and renal complications among pediatric patients with β-TM.

Elevated circulating endothelial microparticles (EMPs) in prepubertal children born preterm

BACKGROUND

Endothelial microparticles (EMPs) act as early biomarkers of endothelial activation and damage. No studies have investigated EMPs in preterm-born individuals.

METHODS

Sixty-three preterm-born children and 52 children born full-term (controls) were studied. Circulating CD62E(+), CD144(+), and CD31(+)/CD42b(-) EMPs were measured in preterm-born children compared to controls; possible associations with cardiovascular risk factors and endothelial function parameters were also assessed.

RESULTS

Circulating CD62E(+), CD144(+), and CD31(+)/CD42b(-) EMPs were significantly higher in preterm-born children compared to controls (p = 0.003, p < 0.001, and p < 0.001, respectively). Preterm birth was recognized as an independent predictor of each EMP subpopulation studied; moreover, the mean pressure and velocity of pulmonary artery were independently correlated with CD62E(+) (β = 0.20, p = 0.04) and CD144(+) EMPs (β = 0.22, p = 0.02), respectively, whereas age (β = 0.21, p = 0.03) and being born SGA (β = 0.26, p = 0.01) correlated independently with CD31(+)/CD42b(-) EMPs in the study population. Furthermore, diastolic blood pressure (β = 0.24, p = 0.04), being born SGA (β = 0.24, p = 0.04) and the hyperemic peak velocity of the brachial artery (β = -0.65, p = 0.02) were independently associated with CD31(+)/CD42b(-) EMPs in the preterm-born group.

CONCLUSION

Circulating EMPs were higher in preterm-born children compared to children born full-term. Whether EMPs could act, in clinical practice, as a complementary tool for non-invasive evaluation of endothelium in preterm-born children, remains under investigation.

IMPACT

Circulating endothelial microparticles (EMPs) are small membrane vesicles released from endothelial cells and they act as novel biomarkers of endothelial activation and damage. No studies have investigated circulating EMPs in preterm-born individuals. Circulating EMPs were significantly higher in prepubertal preterm-born children compared to children born at term. In the preterm-born group, the hyperemic peak velocity of the brachial artery was independently associated with CD31(+)/CD42b(-) EMPs. Whether assessment of circulating EMPs could act, in clinical practice, as a complementary tool for non-invasive evaluation of endothelium in preterm-born children, remains to be defined in future investigations.

Iron overload, oxidative stress and vascular dysfunction: Evidences from clinical studies and animal models

Although iron is a metal involved in many in vital processes due to its redox capacity, body iron overloads lead to tissue damage, including the cardiovascular system. While cardiomyopathy was the focus since the 1960s, the impact on the vasculature was comparatively neglected for about 40 years, when clinical studies correlating iron overload, oxidative stress, endothelial dysfunction, arterial stiffness and atherosclerosis reinforced an "iron hypothesis". Due to controversial results from some epidemiological studies investigating atherosclerotic events and iron levels, well-controlled trials and animal studies provided essential data about the influence of iron, per se, on the vasculature. As a result, the pathophysiology of vascular dysfunction in iron overload have been revisited. This review summarizes the knowledge obtained from epidemiological studies, animal models and "in vitro" cellular systems in recent decades, highlighting a more harmful than innocent role of iron excess for the vascular homeostasis, which supports our proposal to hereafter denominate "iron overload vasculopathy". Additionally, evidence-based therapeutic targets are pointed out to be tested in pre-clinical research that may be useful in cardiovascular protection for patients with iron overload syndromes.

Current status of beta-thalassemia and its treatment strategies

Background

Thalassemia is an inherited hematological disorder categorized by a decrease or absence of one or more of the globin chains synthesis. Beta‐thalassemia is caused by one or more mutations in the beta‐globin gene. The absence or reduced amount of beta‐globin chains causes ineffective erythropoiesis which leads to anemia.

Methods

Beta‐thalassemia has been further divided into three main forms: thalassemia major, intermedia, and minor/silent carrier. A more severe form among these is thalassemia major in which individuals depend upon blood transfusion for survival. The high level of iron deposition occurs due to regular blood transfusion therapy.

Results

Overloaded iron raises the synthesis of reactive oxygen species (ROS) that are noxious and prompting the injury to the hepatic, endocrine, and vascular system. Thalassemia can be analyzed and diagnosed via prenatal testing (genetic testing of amniotic fluid), blood smear, complete blood count, and DNA analysis (genetic testing). Treatment of thalassemia intermediate is symptomatic; however; it can also be accomplished by folic supplementation and splenectomy.

Conclusion

Thalassemia major can be cured through regular transfusion of blood, transplantation of bone marrow, iron chelation management, hematopoietic stem cell transplantation, stimulation of fetal hemoglobin production, and gene therapy.

Assessment of cystatin C in pediatric sickle cell disease and β-thalassemia as a marker of subclinical cardiovascular dysfunction: a case-control study

Cardiovascular complications represent the main determinant of survival in patients with hemoglobinopathies. Serum cystatin C is a well-known marker of nephropathy in sickle cell disease (SCD) and β-thalassemia patients that has recently emerged as a strong predictor of cardiovascular dysfunction in patients with and without kidney disease. We performed a case control study to determine the role of cystatin C as a predictor of subclinical cardiovascular dysfunction in SCD and β-thalassemia patients. We enrolled 40 SCD patients with a mean age of 12.4 years, 40 β-thalassemia patients with a mean age of 11.4 years and 40 age and sex-matched controls. We assessed hematological profile, serum ferritin, urinary albumin-creatinine ratio (UACR), serum cystatin C, echocardiography and carotid intima media thickness (CIMT). UACR, cystatin C and CIMT were higher in SCD and β-thalassemia patients compared to controls (p < .001). Significantly higher cystatin C levels were observed in SCD and β-thalassemia patients with nephropathy or left ventricular systolic dysfunction (shortening fraction <30%, or ejection fraction <55%; p < .001). Moreover, SCD patients with pulmonary hypertension had significantly higher cystatin C levels. Cystatin C levels were positively correlated with CIMT in SCD (p = .02) and β-thalassemia patients (p < .001) while negatively correlated with ejection fraction and shortening fraction (p < .001). The cutoff values of cystatin C ≥ 16.03 and ≥ 13.2 (ng/mL) could detect subclinical cardiac dysfunction risk among SCD and β-thalassemia patients respectively. Cystatin C appears to be a promising marker for subclinical cardiovascular dysfunction in SCD and β-thalassemia patients.

Subclinical atherosclerotic predictive value of inflammatory markers in thalassemia intermedia patients

BACKGROUND

A high incidence of thromboembolic events is observed in thalassemia patients. This study investigated the relationship between carotid intima-media thickness (CIMT) and lipid profile, iron metabolic indices (IMI), and inflammatory markers in β-thalassemia intermedia (β- TI) patients.

PATIENTS AND METHODS

Forty-five β-TI patients at Assiut University Hospital and 34 healthy individuals were enrolled in the study. We measured Lipid profile, IMI, high sensitive CRP (Hs-CRP), and interleukin-6 (IL-6) and compared the results between both groups. We used CIMT measurement as a marker for subclinical atherosclerosis. We used both univariate and multivariate analyses to test relations and independent predictors of CIMT.

RESULTS

β-TI patients had higher CIMT (P = 0.000). CIMT was positively correlated with absolute neutrophil count (ANC) (r = 0.320, p = 0.032), ferritin (r = 0.544, p = 0.000), Hs-CRP (r = 0.603, p = 0.000), and IL-6 (r = 0.520, p = 0.000). Hs-CRP was an independent predictor of CIMT (p = 0.000). Hs-CRP cut off value of 60.4 ug/dl has sensitivity of 63.3% and specificity of 93.3% in predicting premature atherosclerosis.

CONCLUSION

β-TI patients had higher CIMT despite the protective lipid profile. Hs-CRP was an independent predictor of CIMT.

Increased circulating endothelial progenitor cells (EPCs) in prepubertal children born prematurely: a possible link between prematurity and cardiovascular risk

BACKGROUND

Endothelial progenitor cells (EPCs) ensure vascular integrity and neovascularization. No studies have investigated EPCs in preterm-born children beyond infancy.

METHODS

One hundred and thirty-six prepubertal children were enrolled: 63 preterm and 73 born at term (controls). Circulating CD34(+)/VEGFR-2(+)/CD45(-) and CD34(+)/VEGFR-2(+)/CD45dim EPCs were measured in preterm-born children compared to controls. Body mass index (BMI), waist-to-hip ratio (WHR), neck circumference, systolic and diastolic blood pressure (SBP and DBP, respectively), fasting glucose, insulin, lipid profile, common carotid and abdominal aortic intima-media thickness (cIMT and aIMT, respectively), endothelium-dependent brachial artery flow-mediated dilation (FMD), and echocardiographic parameters were also assessed.

RESULTS

Circulating CD34(+)/VEGFR-2(+)/CD45(-) and CD34(+)/VEGFR-2(+)/CD45dim EPCs were significantly higher in preterm-born children compared to controls (p < 0.001 and p < 0.001, respectively). In total study population and in the preterm-born group, EPCs were significantly lower in children born to mothers with gestational diabetes compared to non-diabetic mothers. Prematurity was associated with higher WHR, neck circumference, SBP, DBP, cIMT, aIMT, mean pressure, and velocity of pulmonary artery; the peak velocity of the brachial artery was significantly lower in children born prematurely. In multiple regression analysis, preterm birth and maternal gestational diabetes were recognized as independent predictors of EPCs.

CONCLUSIONS

Circulating EPCs were increased in prepubertal preterm-born children in comparison with peers born full-term. Maternal gestational diabetes was associated with a decrease in EPCs.

IMPACT

Mounting evidence supports the adverse effect of prematurity on cardiovascular health. However, the underlying mechanisms that could lead to endothelial dysfunction in preterm-born individuals are not fully understood. Endothelial progenitor cells (EPCs) ensure vascular integrity, normal endothelial function and neovascularization. No studies have investigated the EPCs counts in peripheral blood beyond infancy in children born prematurely. Circulating EPCs were significantly higher in preterm-born prepubertal children compared to controls, thus indicating that prematurity is possibly associated with endothelial damage. In total study population and in the preterm-born group, maternal gestational diabetes was associated with decreased EPCs concentrations.

Impact of activated monocyte and endothelial dysfunction on coagulopathy in Egyptian adult beta thalassemic patients

The mechanism of the well observed hypercoagulability and high incidence of Thromboembolic Events (TE) in β- thalassemia patients has not been fully elucidated. This study aimed to evaluate evaluate the endothelial dysfunction and monocyte activation among adult Egyptian β-thalassemic patients and assess their role in the hypercoagulability and development of TE. A total of 40 adults patients with bthalassemics and 20 healthy age and sex-matched controls were assessed for endothelial dysfunction using serum Von Willebrand Factor Antigen (VWFAg) and for monocytic activation using flow cytometric assessment of CD14 monocyte microparticles and CD11b activated monocytes. The VWF:Ag level was significantly higher among thalassemic patients (P<0.001) and was positively correlated to development of TE (P<0.05). There was no significance difference for CD14 between patients and controls (P>0.5) and CD11b was higher in controls (P=0.004) with no significant correlation between both and TE development (P>0.05). VWF:Ag is increased in thalassemic patients and could be used as a risk factor for thrombosis in these patients, while no identified role of activated monocytes in thrombotic tendency in such patients.

Assessment of Atherosclerosis in Peripheral and Central Circulation in Adult β Thalassemia Intermedia Patients by Color Doppler Ultrasound: Egyptian Experience

BACKGROUND

Atherosclerosis has been extensively studied in thalassemia major (TM) and sickle cell disease but not yet in β thalassemia intermedia (TI). Previous studies concerned with TM were performed in children. TI patients usually live longer and, thus, are more prone to complications of atherosclerosis.

AIM

In our study, we applied color Doppler for the determination of arterial conduit and flow velocities in β TI patients.

METHODS

For central circulation, we measured right and left middle cerebral arteries (MCAs) and basilar artery (BA) mean flow velocity (MFV), pulsatility index (PI), and peak systolic velocity (PSV) as well as carotid intimal media thickness, and to assess peripheral circulation, we studied ankle/brachial index and posterior and anterior tibial arteries' (ATA, PTA) pressure and PSV. This was applied for 30 adult TI patients and 20 age-, sex-, and ethnic group-matched controls.

RESULTS

Transcranial Doppler findings among cases and controls showed that the MFV, PSV of MCAs, and PSV, PI, and MFV of the BA were statistically higher in cases than controls. A comparison between splenectomized and nonsplenectomized patients showed that total leukocyte count, platelet count, lactate dehydrogenase, ferritin, PSV and MFV of the left MCA were all statistically higher in splenectomized cases. Differences between males and females with TI with respect to laboratory and Doppler findings were all statistically insignificant except for intima media thickness, PTA pressure, ATA pressure, and PSV.

CONCLUSION

More than one parameter should be applied to assess atherosclerosis in TI. There is evidence of an increased risk of central ischemia rather than peripheral ischemia in these patients.

Carotid Doppler ultrasonography as a screening tool of early atherosclerotic changes in children and young adults with β-thalassemia major

PURPOSE

β-thalassemia major (β-TM) patients had an increased incidence of cardiovascular complications secondary to iron overload. They showed early carotid atherosclerosis as showed by increased carotid intima media thickness (CIMT) that may occur early even when significant iron overload is absent. We aimed to test the diagnostic performance of CIMT measurement by Doppler ultrasonography as a structural indicator for premature atherosclerosis in β-TM patients.

METHODS

Case-control study included 42 β-TM patients (24 males and 18 females) aged from 3 to 30 years and 36 age- and sex-matched healthy controls. Carotid Duplex was used for measurement of CIMT in all subjects.

RESULTS

The frequency of abnormal CIMT among patients was 19%. Mean CIMT of right anterior wall was 0.8 ± 0.16 (range 0.5-1.2) mm, of right posterior wall was 0.80 ± 0.17 (range 0.5-1.2), of right lateral wall was 0.8 ± 0.17 (range 0.5-1.1) mm. CIMT of left anterior wall ranged from 0.5 to 1.2 with mean 0.81 ± 0.17, CIMT of left posterior wall ranged from 0.5 to 1.1 with mean 0.80 ± 0.17 mm. Mean CIMT of left lateral wall was 0.81 ± 0.18 mm (range 0.5-1.2). CIMT of right anterior, right posterior and left anterior walls were thicker in patients compared to controls (P = 0.003, 0.015, < 0.001, respectively). There was no observable difference in CIMT between males and females, splenectomised and non-splenectomised, or well and poorly chelated subgroups (P > 0.05). CIMT of right lateral wall correlated with the disease duration (r = 0.3, P = 0.04).

CONCLUSIONS

Carotid ultrasound was a useful tool to detect subclinical atherosclerosis thorough CIMT evaluation in B-thalassemia major patients. B-thalassemia major children proved to have an increased CIMT regardless the state of iron overload.

Coronary atherosclerosis burden is not advanced in patients with β-thalassemia despite premature extracardiac atherosclerosis: a coronary artery calcium score and carotid intima-media thickness study

Background

Thalassemic patients demonstrate an increased rate of extracardiac vascular complications and increased carotid wall intima-media thickness (cIMT), but very low prevalence of coronary artery disease (CAD). We investigated the atheroma burden by assessing the coronary artery calcium (CAC) and cIMT in these patients.

Methods

We examined 37 patients with β-thalassemia and 150 healthy control volunteers with multi-detector computer tomography (CT) and ultrasonography to determine CAC score and cIMT, respectively.

Results

Propensity score matching (C-statistic: 0.88; 95% CI: 0.83–0.93) resulted in 27 pairs of patients; severe CAC was observed in 2 (7.4%) and 0 of β-thalassemia patients and healthy volunteers respectively (P = 0.5). Median calcium score was 0 (0–0) in β-thalassemia patients and 0 (0–4) in healthy volunteers (P = 0.8). Median intima-media thickness was higher in β-thalassemia patients compared to control group [0.45 (0.06–0.65) vs. 0.062 (0.054–0.086); P = 0.04].

Conclusions

Patients with β–thalassemia in comparison with healthy control subjects exhibit similar CAC score and increased cIMT. Our findings indicate a disparate rate of progression of atherosclerosis between coronary and extracardiac arteries in these patients lending support to the epidemiological evidence.

The Role of the Carotid Doppler Examination in the Evaluation of Atherosclerotic Changes in β-Thalassemia Patients

BACKGROUND

Iron overload in patients with beta-thalassemia major (BTM) lead to alterations in the arterial structures and the thickness of the carotid arteries. Doppler ultrasound scanning of extra-cranial internal carotid arteries is non-invasive and relatively quick to perform and may identify children at increased risk of stroke that would otherwise be missed. Increased carotid artery intima media thickness (CIMT) is a structural marker for early atherosclerosis and correlates with the vascular risk factors and to the severity and extent of coronary artery disease.

OBJECTIVE

To evaluate the role of carotid Doppler examination and CIMT measurement as a predictor of atherosclerotic changes in BTM children with iron overload.

PATIENTS AND METHODS

Sixty two children with BTM and, thirty age and sex matched normal controls were included. Complete blood count, ferritin, serum cholesterol were done, as well as carotid Doppler ultrasonography to measure the CIMT in both patients and controls.

RESULTS

CIMT of thalassemic patients was significantly increased compared to controls (p=0.001). There was a significant positive correlation between CIMT and patient's age, the duration from first blood transfusion, serum cholesterol and, iron overload parameters as serum ferritin, frequency of blood transfusion, iron chelation. The length of the transfusion period was the highest risk factor, and an inadequate iron chelation was a further risk factor. Significant negative correlation was found between CIMT and hematocrit value while no significant correlation was found between CIMT and weight, height, BMI centiles and Hb level.

CONCLUSION

Carotid Doppler is very useful in measurement of CIMT that increased in thalassemic patients that shows a strong relationship with features of iron overload. Routine Doppler measurement of CIMT in these patients is recommended to predict early atherosclerotic changes as well as in follow-up.