Association of iron overload based quantitative T2* MRI technique and carotid intima-media thickness in patients with beta-thalassemia: a cross-sectional study

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.

Surrogate Markers of Subclinical Atherosclerosis and Its Associated Factors in Patients with β-Thalassemia Major

β-Thalassemia major (β-TM) is a severe genetic hemoglobin (Hb) disorder with cardiovascular complications such as atherosclerosis due to transfusion-dependent iron overload. We aimed to determine the associated factors with surrogate markers of subclinical atherosclerosis in these patients. Sixty subjects with β-TM referred to the Thalassemia Clinic of the Iranian Blood Transfusion Organization (IBTO) were included in our study. The blood samples were collected for laboratory measurements. The carotid intima-media thickness (CIMT), was measured by ultrasonography, and ankle-brachial index (ABI) was calculated. The multivariate linear analysis was performed to determine the appropriate indicators of subclinical atherosclerosis in β-TM. There was no significant difference in baseline characteristics between the study groups. In multivariate linear analysis, age and systolic blood pressure (SBP) were negatively associated with inverse-transformed CIMT [unstandardized β coefficient (B): -0.024, 95% confidence interval (95% CI): -0.032- -0.010, p < 0.001; B: -0.009, 95% CI: -0.017- -0.001, p 0.031, respectively]. There was also a significant correlation between the serum level of high-density lipoprotein cholesterol (HDL-C) and insulin with higher ABI, after adjustment for confounding variables (B: 0.003; 95% CI: 0.000-0.005; p = 0.030, and B: 0.004, 95% CI: 0.000-0.009, p = 0.037, respectively). Our results show that advancing age and increased SBP, HDL-C and insulin, associated with higher CIMT or ABI, are appropriate indicators of subclinical atherosclerosis in β-TM patients.

The relationship between myocardial and hepatic T2 and T2* at 1.5T and 3T MRI in normal and iron-overloaded patients

Background Cardiac and liver iron assessment using magnetic resonance imaging (MRI) is non-invasive and used as a preclinical "endpoint" in asymptomatic patients and for serial iron measurements in iron-overloaded patients. Purpose To compare iron measurements between hepatic and myocardial T2* and T2 at 1.5T and 3T MRI in normal and iron-overloaded patients. Material and Methods The T2 and T2* values from the regions of interest (ROIs) at mid-left ventricle and mid-hepatic slices were evaluated by 1.5T and 3T MRI scans for healthy and iron-overloaded patients. Results For iron-overloaded patients, the myocardial T2 (1.5T) and myocardial T2 (3T) values were 60.3 ms (range = 56.2-64.8 ms) and 55 ms (range = 51.6-60.1 ms) (ρ = 0.3679) while the myocardial T2* (3T) 20.5 ms (range = 18.4-25.9 ms) was shorter than the myocardial T2* (1.5T) 35.9 ms (range = 31.4-39.5 ms) (ρ = 0.6454). The hepatic T2 at 1.5T and 3T were 19.1 ms (range = 14.8-27.9 ms) and 15.5 ms (14.6-20.4 ms) (ρ = 0.9444) and the hepatic T2* at 1.5T and 3T were 2.7 ms (range = 1.8-5.6 ms) and 1.8 ms (range = 1.1-2.9 ms) (ρ = 0.9826). The line of best fit exhibiting the linearity of the hepatic T2* (1.5T) and hepatic T2* (3T) had a slope of 2 and an intercept of -0.387 ms (R = 0.984). Conclusion Our study found myocardial T2 (1.5T) nearly equal to T2 (3T) with myocardial T2* (3T) 1.75 shorter than myocardial T2* (1.5T). The relationship of hepatic T2* (1.5T) and hepatic T2* (3T) was linear with T2* (1.5T) approximately double to T2* (3T) in iron-overloaded patients. This linear relationship between hepatic T2* (1.5T) and hepatic T2 (3T) could be an alternative method for estimating liver iron concentration (LIC) from 3T.

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.

Evaluation of carotid artery dynamics & correlation with cardiac & hepatic iron in β-thalassaemia patients

Background & objectives:

Early atherosclerosis and vascular complication have been described in thalassaemia patients. There is lack of data or guidelines regarding monitoring of vascular health in thalassaemia. This study was conducted to compare carotid artery structural and functional indices such as carotid artery intima-media thickness (CIMT), stiffness index (SI) and Young's elastic modulus (YEM) in β-thalassemia patients with age and sex matched controls, and to correlate these parameters with serum ferritin, cardiac iron, and hepatic iron.

Methods:

This cross-sectional study included 53 β-thalassaemia patients receiving regular blood transfusions. Carotid artery indices such as CIMT, SI, and YEM were calculated by duplex ultrasound and colour Doppler. Serum ferritin levels were measured by chemiluminescence. Cardiac and hepatic iron estimation were done using MRI T2* sequences analyzed by a special thalassaemia software.

Results:

Mean CIMT of cases and controls were 0.48 ± 0.04 and 0.44±0.02 mm, respectively and these were significantly different (P<0.001). Similarly significant differences were noted in SI and YEM of cases (2.45±0.79 and 96.12±34.85, respectively) as compared to controls (1.98±0.54 and 68.60±24.29, respectively) (P<0.001). There was significant inverse correlation between stiffness index and cardiac iron overload assessed by MRI cardiac T2* (P=0.03). Mean SI and YEM of cases were (2.1736 ± 0.2986 and 107.3± 41.6, respectively) significantly higher among non-splenectomized patients compared to splenectomized patients (2.0136 ± 0.263 and 86.9 ± 25.2, respectively) (P<0.05).

Interpretation & conclusions:

CIMT and arterial stiffness indices were significantly increased in β-thalassaemia patients compared to controls which was indicative of early atherogenic changes. This study supports the hypothesis that iron overload is a risk factor for early atherosclerosis and cardiovascular disease.

Low Dose Iron Treatments Induce a DNA Damage Response in Human Endothelial Cells within Minutes

BACKGROUND

Spontaneous reports from patients able to report vascular sequelae in real time, and recognition that serum non transferrin bound iron may reach or exceed 10μmol/L in the blood stream after iron tablets or infusions, led us to hypothesize that conventional iron treatments may provoke acute vascular injury. This prompted us to examine whether a phenotype could be observed in normal human endothelial cells treated with low dose iron.

METHODOLOGY

Confluent primary human endothelial cells (EC) were treated with filter-sterilized iron (II) citrate or fresh media for RNA sequencing and validation studies. RNA transcript profiles were evaluated using directional RNA sequencing with no pre-specification of target sequences. Alignments were counted for exons and junctions of the gene strand only, blinded to treatment types.

PRINCIPAL FINDINGS

Rapid changes in RNA transcript profiles were observed in endothelial cells treated with 10μmol/L iron (II) citrate, compared to media-treated cells. Clustering for Gene Ontology (GO) performed on all differentially expressed genes revealed significant differences in biological process terms between iron and media-treated EC, whereas 10 sets of an equivalent number of randomly selected genes from the respective EC gene datasets showed no significant differences in any GO terms. After 1 hour, differentially expressed genes clustered to vesicle mediated transport, protein catabolism, and cell cycle (Benjamini p = 0.0016, 0.0024 and 0.0032 respectively), and by 6 hours, to cellular response to DNA damage stimulus most significantly through DNA repair genes FANCG, BLM, and H2AFX. Comet assays demonstrated that 10μM iron treatment elicited DNA damage within 1 hour. This was accompanied by a brisk DNA damage response pulse, as ascertained by the development of DNA damage response (DDR) foci, and p53 stabilization.

SIGNIFICANCE

These data suggest that low dose iron treatments are sufficient to modify the vascular endothelium, and induce a DNA damage response.

Assessment of Myocardial Performance Index and Aortic Elasticity in Patients With Beta-Thalassemia Major

BACKGROUND

This study aimed to assess myocardial performance index (MPI) and arterial elasticity indices in asymptomatic patients with beta-thalassemia major without known heart disease and to determine relationship between these indices and parameters indicating iron load of body.

METHODS

The study included 55 asymptomatic beta-thalassemia patients (median age: 20 years (10 - 48 years)) without known history of heart disease and 40 age- and sex-matched healthy controls. MPI and arterial elasticity indices were determined by using standard two-dimensional and Doppler echocardiography. Data were analyzed by SPSS for Windows version 20.0 (SPSS Inc., Chicago, IL, USA).

RESULTS

Left ventricular mass index (83.917 (50.62 - 144) and 68.37 (41.9 - 113.3)) and MPI (0.464 (0.33 - 0.68) and 0.431 (0.31 - 0.51)) were significantly higher in patients with beta-thalassemia when compared to control group (P < 0.001 and P = 0.006). Aortic elasticity indices were significantly higher while aortic strain and distensibility values were significantly lower in patients with beta-thalassemia compared to controls (all P values < 0.001). Positive correlations were detected between aortic stiffness index and platelet (r = 0.235; P = 0.019) and ferritin values (r = 0.328; P = 0.008). Presence of thalassemia (β = -0.729; P = 0.041) and higher platelet value (β = 0.235; P = 0.019) were significant determinants for increased aortic stiffness in linear regression analysis.

CONCLUSION

Arterial elasticity indices and MPI are impaired in patients with beta-thalassemia major and these parameters may be used to predict cardiovascular complications in asymptomatic patients with beta-thalassemia major.

Carotid endarterectomy in a young symptomatic patient with B-thalassemia major

β-Thalassemia major promotes atherosclerotic process, although the debating literature concerning the lipidic profile of young patients; it is well accepted that there is early vascular destruction in these homozygous patients either as a direct consequence of the genetic disorder per se or because of the repeated transfusions and the iron overload. Despite the potential of the disease for local brain thrombotic events, accelerated atheromatosis can lead to early thromboembolic events. We present an interesting case of a 36-year-old man with unilateral embolic infarcts (repeated transient ischemic attacks) originated from a near occlusion right carotid stenosis with additional peripheral thrombus. The patient underwent a successful carotid endarterectomy with primary arterial closure with uneventful postoperative course, confirmed by a clear postoperative angiography; he remains asymptomatic 18 months later. To the best of our knowledge, this is the first case of a young symptomatic patient with β-thalassemia major who underwent carotid repair.

Haptoglobin genotypes polymorphism as a risk factor for subclinical atherosclerosis in beta-thalassemia major children; a single center Egyptian study

Background/Objectives Haptoglobin (Hp) is an antioxidant protein. Its genotypic polymorphism had been proposed to influence vascular complications among diabetics, but no data are available about this association among thalassemia patients so far. We have investigated the assumption of an association between Hp genotypes and subclinical atherosclerosis among beta-thalassemia major (TM) children. Methods One hundred beta-TM children and 70 matched healthy controls were included. Serum ferritin level and fasting lipid profile were assayed. Haptoglobin genotyping was determined by amplification gel electrophoresis. Carotid intima media thickness (cIMT) was measured using high resolution ultrasound. Results The relative distribution of the three Hp genotypes among thalassemia group and the control group were 18 and 14.3% for Hp1-1; 38 and 37.1% for Hp2-1; and 44 and 48.6% for Hp2-2 respectively. There was no significant difference between patients and controls regarding Hp genotypes distribution. Hp2-2 genotype TM children had significantly higher cIMT compared to other genotypes (P < 0.0001). Elevated cIMT was significantly represented in Hp2-2 genotype patients (P < 0.0001) who had higher serum ferritin compared to their counterparts (P < 0.05). Hp2-2 patients were five times more likely to suffer from subclinical atherosclerosis than Hp1-1 and six times than Hp2-1 genotype patients (P = 0.008 and 0.001, respectively); a difference that persisted significant after adjustment for some risk factors compared to Hp2-1 patients (OR 3.96; P = 0.02). Conclusions Hp2-2 genotype is a significant predictor for premature atherosclerosis in TM children and confers them an increased risk for iron overload.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) and tumor necrosis factor-alpha (TNF-α) and their relation to premature atherosclerosis in β-thalassemia children

BACKGROUND/OBJECTIVES

Beta (β)-thalassemia adults are prone to premature atherosclerosis but data about this complication among thalassemia children are few. Lipoprotein-associated phospholipase A2 (Lp-PLA2) and tumor necrosis factor-α (TNF-α) are inflammatory markers that could be implicated in atherosclerotic process. We investigated Lp-PLA2 and TNF-α levels in β-thalassemia children and their relation to subclinical atherosclerosis.

METHODS

Twenty-two β-thalassemia major (TM), 20 β-thalassemia intermedia children, and 30 age- and sex-matched healthy controls were included. Lipid profile (by colorimetric assay), serum ferritin, TNF-α, and plasma Lp-PLA2 levels (by enzyme-linked immunosorbent assay technique) were estimated. Carotid intima-media thickness (cIMT) was measured by high-resolution ultrasound.

RESULTS

Both patient groups exhibited anti-atherogenic lipid profile except increased serum triglycerides. They had significantly higher plasma Lp-PLA2 and serum TNF-α compared to the controls (P < 0.001). Elevated cIMT was documented in 57% of the thalassemia children and was higher among hepatitis C (HCV) positive patients. Serum ferritin, TNF-α, and plasma Lp-PLA2 levels were significantly higher in patients with premature atherosclerosis. cIMT correlated significantly with serum ferritin, TNF-α, and plasma Lp-PLA2 in both patient groups. Among TM children, serum ferritin had significant positive correlation with serum TNF-α and plasma Lp-PLA2. The elevation of both markers was not related to HCV infection.

CONCLUSIONS

Premature atherosclerosis is common among young thalassemia children. Lp-PLA2 and TNF-α are significantly increased in thalassemia children and show strong correlations with cIMT, suggesting that both of them may be appreciated as modulating factors in carotid atherosclerosis pathophysiological process among these children.

Early identification of cardiovascular involvement in patients with β-thalassemia major

The aim of the present study was to evaluate left ventricular myocardial deformation and carotid arterial stiffness using 2-dimensional strain and echo-tracking in patients with asymptomatic β-thalassemia major (β-TM) without significant myocardial iron overload to determine whether early subclinical cardiovascular abnormalities would be detectable. We enrolled 32 patients with β-TM (23 women, mean age 35 ± 8 years) and 33 healthy volunteers (20 women, mean age 35 ± 6 years). All subjects underwent echocardiography with 2-dimensional strain analysis (XStrain) and ultrasonography of the carotid arteries with measurement of the stiffness parameters (ProSound Alpha 10). Cardiac magnetic resonance imaging using a T2* algorithm (37.7 ± 5.6 ms) for the assessment of myocardial iron overload was performed in each patient. The clinical and standard echocardiographic parameters were comparable between the patients and healthy subjects. The global left ventricular longitudinal strain was significantly impaired in the patients compared with the controls (-17.9 ± 3.5% vs -24.3 ± 3.4%, p = 0.002), although the radial and circumferential strain values were similar between the 2 groups (p = NS for both). The carotid intima-media thickness was comparable between the patients and healthy subjects (0.67 ± 0.20 mm vs 0.66 ± 0.15 mm, p = NS). In contrast, the arterial stiffness was significantly increased in the patients compared with the controls (stiffness index 6.16 ± 1.31 vs 4.65 ± 0.82, p <0.001; arterial compliance 1.10 ± 0.26 vs 1.28 ± 0.30 cm(2)/mm Hg, p = 0.027; elastic modulus 74.1 ± 19.5 vs 59.1 ± 12.1 mm Hg, p = 0.001). In conclusion, cardiovascular abnormalities, although often subclinical, occur at an early stage of β-TM and also in the absence of significant iron overload. Thus, 2-dimensional strain and echo-tracking might be more accurate than standard echocardiography and vascular parameters in the early identification of cardiovascular involvement.