Cardiac iron measurement and iron chelation therapy in patients with β thalassaemia major: experience from Taiwan

The role of iron overload and ferroptosis in arrhythmia pathogenesis

Ferroptosis is a newly discovered form of programmed cell death triggered by intracellular iron overload, which leads to the accumulation of lipid peroxides in various cells. It has been implicated in the pathogenesis and progression of various diseases, including tumors, neurological disorders, and cardiovascular diseases. The intricate mechanism underlying ferroptosis involves an imbalance between the oxidation and antioxidant systems, disturbances in iron metabolism, membrane lipid peroxidation, and dysregulation of amino acid metabolism. We highlight the key molecular mechanisms governing iron overload and ferroptosis, and discuss potential molecular pathways linking ferroptosis with arrhythmias.

Ferroptosis mechanisms and regulations in cardiovascular diseases in the past, present, and future

Cardiovascular diseases (CVDs) are the main diseases that endanger human health, and their risk factors contribute to high morbidity and a high rate of hospitalization. Cell death is the most important pathophysiology in CVDs. As one of the cell death mechanisms, ferroptosis is a new form of regulated cell death (RCD) that broadly participates in CVDs (such as myocardial infarction, heart transplantation, atherosclerosis, heart failure, ischaemia/reperfusion (I/R) injury, atrial fibrillation, cardiomyopathy (radiation-induced cardiomyopathy, diabetes cardiomyopathy, sepsis-induced cardiac injury, doxorubicin-induced cardiac injury, iron overload cardiomyopathy, and hypertrophic cardiomyopathy), and pulmonary arterial hypertension), involving in iron regulation, metabolic mechanism and lipid peroxidation. This article reviews recent research on the mechanism and regulation of ferroptosis and its relationship with the occurrence and treatment of CVDs, aiming to provide new ideas and treatment targets for the clinical diagnosis and treatment of CVDs by clarifying the latest progress in CVDs research.

Ferroptosis in cardiovascular disease

In the 21st century, cardiovascular disease (CVD) has become one of the leading causes of death worldwide. The prevention and treatment of CVD remain pressing scientific issues. Several recent studies have suggested that ferroptosis may play a key role in CVD. Most studies conducted thus far on ferroptosis and CVD have supported the link. Ferroptosis mediated by different signaling and metabolic pathways can lead to ischemic heart disease, myocarditis, heart failure, ischemia-reperfusion injury, and cardiomyopathy. Still, the specific mechanism of ferroptosis in CVD, the particular organ areas affected, and the stage of disease involved need to be further studied. Therefore, understanding the mechanisms regulating ferroptosis in CVD may improve disease management. Throughout this review, we summarized the mechanism of ferroptosis and its effect on the pathogenesis of CVD. We also predicted and discussed future research directions, aiming to provide new ideas and strategies for preventing and treating CVD.

Serum Ferritin Levels and Other Associated Parameters with Diabetes Mellitus in Adult Patients Suffering from Beta Thalassemia Major

Background

Although beta thalassemia major (BTM) patients are properly treated with blood transfusions in accompany with iron chelation therapy, they suffer from complications, such as diabetes mellitus (DM).

Purpose

The purpose was to detect the critical serum ferritin level and other parameters correlated with DM among adult BTM patients. Also, it was to study whether each of these parameters is associated with a certain period of age.

Patients and Methods

This study included 200 adult BTM patients. A cross-sectional study was carried out. Patients clinical and laboratory variables, such as ferritin levels, and fasting blood glucose (FBS) were extracted from medical records at Zagazig University Hospital, Egypt. Liver and cardiac iron contents were assessed using MRI T2* methods. Statistical analysis was performed using IBM SPSS V26.0 software package.

Results

The overall frequency of DM over the total sample equals 6.5%. There were no impaired fasting glucose (IFG) in the medical records. Statistical significance between serum ferritin and DM was (P = 0.014). The serum ferritin 2500 ng/mL with age group (27-<32) years-old were risk factors. The distributions of DM according to BMI were (3.5%) of class overweight. Significant association between DM and BMI was (r = 0.357, P < 0.001). Liver MRI T2* has significant correlation with serum ferritin, but cardiac MRI T2* was poorly correlated. Association between liver and cardiac MRI T2* was not found.

Conclusion

Age group (27-<32) years-old and ferritin >2500 ng/mL should be properly treated immediately. The serum ferritin and BMI of class "overweight" were risk factors for DM. Factors such as diet should be followed. Serum ferritin can be used for estimating liver iron content for economic factors. But cardiac MRI T2* must be performed for evaluating cardiac iron accurately.

Iron in Cardiovascular Disease: Challenges and Potentials

Iron is essential for many biological processes. Inadequate or excess amount of body iron can result in various pathological consequences. The pathological roles of iron in cardiovascular disease (CVD) have been intensively studied for decades. Convincing data demonstrated a detrimental effect of iron deficiency in patients with heart failure and pulmonary arterial hypertension, but it remains unclear for the pathological roles of iron in other cardiovascular diseases. Meanwhile, ferroptosis is an iron-dependent cell death that is distinct from apoptosis, necroptosis, and other types of cell death. Ferroptosis has been reported in several CVDs, namely, cardiomyopathy, atherosclerotic cardiovascular disease, and myocardial ischemia/reperfusion injury. Iron chelation therapy seems to be an available strategy to ameliorate iron overload-related disorders. It is still a challenge to accurately clarify the pathological roles of iron in CVD and search for effective medical intervention. In this review, we aim to summarize the pathological roles of iron in CVD, and especially highlight the potential mechanism of ferroptosis in these diseases.

Cardiomyopathy in Thalassemia: Quick Review from Cellular Aspects to Diagnosis and Current Treatments

BACKGROUND

Cardiomyopathic manifestations induced by continuous blood transfusion are the leading cause of death among patients with thalassemia major (TM). Despite introduction of chelation therapy, heart failure after cardiomyopathic manifestations is still a major threat to patients.

METHODS

We performed a search of relevant English-language literature, retrieving publications from the PubMed database and the Google Scholar search engine (2005-2018). We used "thalassemia major", "cardiomyopathy", "iron overload", "cardiac magnetic resonance T2" "chelation therapy", and "iron burden" as keywords.

RESULTS

The results of the studies we found suggest that cardiac hepcidin is a major regulator of iron homeostasis in cardiac tissue. Unlike previous assumptions, the heart appears to have a limited regeneration capability, originating from a small population of hypoxic cardiomyocytes.

CONCLUSIONS

Oxygen levels determine cardiomyocyte gene-expression patterns. Upregulation of cardiac hepcidin in hypoxia preserves cardiomyocytes from forming out of reactive oxygen species catalyzed by free cellular iron in cardiomyocytes. Using the limited regeneration capacity of cardiac cells and gaining further understanding of the cellular aspects of cardiomyopathic manifestations may help health care professionals to develop new therapeutic strategies.

Iron overload and arrhythmias: Influence of confounding factors

Arrhythmias as a cardiac complication of iron overload (IO) have been well described for decades in the clinical literature. They are assumed to be directly associated with the myocardial accumulation of iron. However, the influence of heart failure and elevated oxidative stress, which are major arrhythmogenic confounding factors associated with IO on arrhythmias, has not been critically reviewed in the published literature. A comprehensive narrative review of published articles in PubMed was conducted to address the influence of confounding factors of IO on arrhythmias. The previous data may have been largely confounded by the other cardiac complications of IO, particularly heart failure. The previous studies on IO-related arrhythmias lack proper age-gender-matched control subjects and/or comparison groups with properly controlled confounding factors to assess accurately their etiology and clinical significance. Given the above considerations, further mechanistic investigations to clarify the etiology and clinical relevance of IO-induced arrhythmias are needed. In addition, investigations to develop arrhythmia management strategy specific to IO, are warranted.

The long-term efficacy and tolerability of oral deferasirox for patients with transfusion-dependent β-thalassemia in Taiwan

Deferasirox is a novel once-daily, oral iron chelator. The aim of this study was to evaluate the long-term efficacy and tolerability of deferasirox in Taiwanese patients with transfusion-dependent β-thalassemia who have been treated with deferasirox for 7 years. Taiwanese patients aged ≥2 years with transfusion-dependent β-thalassemia whose serum ferritin levels were ≥1000 ng/mL and had started deferasirox treatment since December 2005 at the National Taiwan University Hospital were enrolled. Sixty patients were recruited for analysis, and 11 (18.3 %) patients discontinued deferasirox during the study. In the 42 patients included in the efficacy analysis, the mean serum ferritin levels decreased significantly by 2566 ng/mL after 7 years of treatment (P < 0.001). Forty-one of these patients received a cardiac T2* evaluation after 3 years of deferasirox treatment, and the mean cardiac T2* value increased significantly from 30.6 ± 16.6 to 45.9 ± 22.6 ms after 7 years of deferasirox treatment (P < 0.001). Deferasirox-related adverse events assessed by investigators were reported in 46 (76.7 %) patients. The most common adverse events related to deferasirox were skin rashes (n = 29, 48.3 %), followed by abdominal pain (n = 23, 38.3 %) and diarrhea (n = 16, 26.7 %). Most adverse events were manageable. This study demonstrated that long-term treatment with deferasirox was effective in improving iron overload, including cardiac iron overload, in patients with transfusion-dependent β-thalassemia. Deferasirox was well tolerated; however, the incidences of common adverse events related to deferasirox appeared higher in our Taiwanese patients than other studies.

Glutathione S-transferase gene polymorphism: Relation to cardiac iron overload in Egyptian patients with Beta Thalassemia Major

OBJECTIVES

Estimating the prevalence of glutathione S-transferase gene polymorphism (GSTM1) null genotype among patients with beta thalassemia major (β-TM) in relation to myocardial status assessed by tissue Doppler and cardiac siderosis assessed by cardiac magnetic resonance imaging (MRI) T2*.

METHODS

Hundred patients with β-TM and 100 healthy controls were enrolled. Complete blood count (CBC), mean serum ferritin and GSTM1 genotyping, echocardiography, tissue Doppler, and cardiac MRI T2* were done.

RESULTS

Serum ferritin ranged from 1200 to 8000 ng/ml, and mean T2* value was 27.10 ± 11.20 ms. Of patients, 68 (68%) had no cardiac siderosis, while 24 (24%) with mild to moderate, and 8 (8%) with sever cardiac siderosis. T2* values were not correlated with serum ferritin (r = -0.09, P = 0.50). GSTM1 null genotype was prevalent in 46% of patients and 40% of controls (P = 0.69). Patients with null genotype had significantly shorter T2* (P = 0.001), higher left ventricular end-diastolic diameter (P = 0.002), and shorter ejection time (P = 0.005) with no significant relation to serum ferritin (P = 0.122). GSTM1 null genotype was the only predictor for cardiac iron overload (P = 0.002).

DISCUSSION

Serum ferritin concentrations have been shown to correlate poorly with all stages of cardiac dysfunction. Low cardiac MRI T2* values occur in patients with β-TM despite good chelation therapy, suggesting a possible role of genetic factors in cardiac siderosis.

CONCLUSION

GSTM1 null genotype is significantly associated with cardiac iron overload independent of serum ferritin in Egyptian patients with β-TM.

Percutaneous excretion of iron and ferritin (through Al-hijamah) as a novel treatment for iron overload in beta-thalassemia major, hemochromatosis and sideroblastic anemia

Iron overload is a big challenge when treating thalassemia (TM), hemochromatosis and sideroblastic anemia. It persists even after cure of TM with bone marrow transplantation. Iron overload results from increased iron absorption and repeated blood transfusions causing increased iron in plasma and interstitial fluids. Iron deposition in tissues e.g. heart, liver, endocrine glands and others leads to tissue damage and organ dysfunction. Iron chelation therapy and phlebotomy for iron overload have treatment difficulties, side effects and contraindications. As mean iron level in skin of TM patients increases by more than 200%, percutaneous iron excretion may be beneficial. Wet cupping therapy (WCT) is a simple, safe and economic treatment. WCT is a familiar treatment modality in some European countries and in Chinese hospitals in treating different diseases. WCT was reported to clear both blood plasma and interstitial spaces from causative pathological substances (CPS). Standard WCT method is Al-hijamah (cupping, puncturing and cupping, CPC) method of WCT that was reported to clear blood and interstitial fluids better than the traditional WCT (puncturing and cupping method, PC method of WCT). In other word, traditional WCT may be described as scarification and suction method (double S technique), while Al-hijamah may be described as suction, scarification and suction method (triple S technique). Al-hijamah is a more comprehensive treatment modality that includes all steps and therapeutic benefits of traditional dry cupping therapy and WCT altogether according to the evidence-based Taibah mechanism (Taibah theory). During the first cupping step of Al-hijamah, a fluid mixture is collected inside skin uplifting due to the effect of negative pressure inside sucking cups. This fluid mixture contains collected interstitial fluids with CPS (iron, ferritin and hemolyzed RBCs in thalassemia), filtered fluids (from blood capillaries) with iron and hemolyzed blood cells (hemolyzed RBCs, WBCs and platelets). That fluid mixture does not contain intact blood cells (having diameters in microns) that are too big to pass through pores of skin capillaries (6-12nm in diameter) and cannot be filtered. Puncturing skin upliftings and applying second cupping step excrete collected fluids. Skin scarifications (shartat mihjam in Arabic) should be small, superficial (0.1mm in depth), short (1-2mm in length), multiple, evenly distributed and confined to skin upliftings. Sucking pressure inside cups (-150 to -420mmHg) applied to skin is transmitted to around skin capillaries to be added to capillary hydrostatic pressure (-33mmHg at arterial end of capillaries and -13mmHg at venous end of capillaries) against capillary osmotic pressure (+20mmHg). This creates a pressure gradient and a traction force across skin and capillaries and increases filtration at arterial end of capillaries at net pressure of -163 to -433mmHg and at venous end of capillaries at net pressure of -143 to -413mmHg resulting in clearance of blood from CPS (iron, ferritin and hemolyzed blood cells). Net filtration pressure at renal glomeruli is 10mmHg i.e. Al-hijamah exerts a more pressure-dependent filtration than renal glomeruli. Al-hijamah may benefit patients through inducing negative iron balance. Interestingly, Al-hijamah was reported to decrease serum ferritin significantly (by about 22%) in healthy subjects while excessive traditional WCT was reported to cause iron deficiency anemia. Al-hijamah is a highly recommended treatment in prophetic medicine. In conclusion, Al-hijamah may be a promising adjuvant treatment for iron overload in TM, hemochromatosis and sideroblastic anemia.

Spatial repolarization heterogeneity detected by magnetocardiography correlates with cardiac iron overload and adverse cardiac events in beta-thalassemia major

Background

Patients with transfusion-dependent beta-thalassemia major (TM) are at risk for myocardial iron overload and cardiac complications. Spatial repolarization heterogeneity is known to be elevated in patients with certain cardiac diseases, but little is known in TM patients. The purpose of this study was to evaluate spatial repolarization heterogeneity in patients with TM, and to investigate the relationships between spatial repolarization heterogeneity, cardiac iron load, and adverse cardiac events.

Methods and Results

Fifty patients with TM and 55 control subjects received 64-channel magnetocardiography (MCG) to determine spatial repolarization heterogeneity, which was evaluated by a smoothness index of QT_c (SI-QT_c), a standard deviation of QT_c (SD-QT_c), and a QT_c dispersion. Left ventricular function and myocardial T2* values were assessed by cardiac magnetic resonance. Patients with TM had significantly greater SI-QT_c, SD-QT_c, and QT_c dispersion compared to the control subjects (all p values<0.001). Spatial repolarization heterogeneity was even more pronounced in patients with significant iron overload (T2*<20 ms, n = 20) compared to those with normal T2* (all p values<0.001). Log_e cardiac T2* correlated with SI-QT_c (r = −0.609, p<0.001), SD-QT_c (r = −0.572, p<0.001), and QT_c dispersion (r = −0.622, p<0.001), while all these indices had no relationship with measurements of the left ventricular geometry or function. At the time of study, 10 patients had either heart failure or arrhythmia. All 3 indices of repolarization heterogeneity were related to the presence of adverse cardiac events, with areas under the receiver operating characteristic curves (ranged between 0.79 and 0.86), similar to that of cardiac T2*.

Conclusions

Multichannel MCG demonstrated that patients with TM had increased spatial repolarization heterogeneity, which is related to myocardial iron load and adverse cardiac events.

Diabetes mellitus in patients with thalassemia major

BACKGROUND

Diabetes mellitus is a major endocrinopathy for patients with thalassemia major. Although diabetes mellitus is multifactorial, iron loading is its primary cause and its management poses a clinical challenge. Detecting the pre-diabetes stage is critical because clinical diabetes can potentially be reversed or prevented.

PROCEDURE

Patients with thalassemia major who received regular blood transfusion therapy from 1994 to 2010 were evaluated for the incidence of diabetes mellitus and glucose dysregulation. The association between patients' clinical, biochemical, and image parameters was also evaluated.

RESULTS

The patients with diabetes were significantly older, had higher ferritin levels, a smaller pancreas volume, and lower cardiac T2* magnetic resonance imaging (MRI) values than the patients without diabetes. The pancreas T2* MRI values were higher in the patients without diabetes, but the difference was not statistically significant. The liver iron concentration did not differ between the patients with and without diabetes. The prevalence of hepatitis C infection and hypogonadism was also higher in the patients with diabetes. In the patients without diabetes, the cardiac T2* MRI values were higher in patients with normal fasting glucose levels (P = 0.03), and the homeostasis model assessment of insulin resistance level was associated with hepatitis C infection (P = 0.024, r = 0.32) and hypogonadism (P = 0.034, r = 0.301).

CONCLUSIONS

Fasting glucose and insulin levels were appropriate screening tools for evaluating glucose dysregulation and complemented the MRI findings. The cardiac T2* and pancreas volumes were significant predictors of diabetes.

The Role of Cardiovascular Magnetic Resonance (CMR) and Computed Tomography (CCT) in Facilitating Heart Failure Management

OPINION STATEMENT

Cardiovascular magnetic resonance (CMR) and cardiac computed tomography (CCT) offer advantages for detecting left or right ventricular dysfunction in patients with or suspected of heart failure. CMR does not expose patients to ionizing radiation, and thus is well-suited for functional assessments and serial studies. CCT provides high spatial resolution, making it useful for the identification of coronary arteriosclerosis associated with ischemic cardiomyopathy. In this review, the clinical applications of CMR and CCT are individually discussed, with comparisons made between them to examine the strengths of each modality. The major techniques for each modality are outlined, as well as their uses for the evaluation of cardiomyopathy in heart failure patients with reduced left ventricular ejection fraction, preserved left ventricular ejection fraction, and valvular heart disease. Finally, we review the utility of CMR and CCT in determining which patients will benefit from cardiac resynchronization therapy.