Iron chelation therapy in the management of transfusion-related cardiac iron overload

Deferoxamine B: A Natural, Excellent and Versatile Metal Chelator

Deferoxamine B is an outstanding molecule which has been widely studied in the past decade for its ability to bind iron and many other metal ions. The versatility of this metal chelator makes it suitable for a number of medicinal and analytical applications, from the well-known iron chelation therapy to the most recent use in sensor devices. The three bidentate hydroxamic functional groups of deferoxamine B are the centerpiece of its metal binding ability, which allows the formation of stable complexes with many transition, lanthanoid and actinoid metal ions. In addition to the ferric ion, in fact, more than 20 different metal complexes of deferoxamine b have been characterized in terms of their chemical speciation in solution. In addition, the availability of a terminal amino group, most often not involved in complexation, opens the way to deferoxamine B modification and functionalization. This review aims to collect and summarize the available data concerning the complex-formation equilibria in solutions of deferoxamine B with different metal ions. A general overview of the progress of its applications over the past decade is also discussed, including the treatment of iron overload-associated diseases, its clinical use against cancer and neurodegenerative disorders and its role as a diagnostic tool.

Carvedilol improves left ventricular diastolic dysfunction in patients with transfusion-dependent thalassemia

Background:

Iron overload cardiomyopathy is the most common cause of death in patients with transfusion-dependent thalassemia.

Aim:

The aim of this study was to determine the efficacy of carvedilol treatment in patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction.

Methods:

Eighteen patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction were enrolled. All patients had normal left ventricular systolic function and were given carvedilol with the target dose of 0.8 mg/kg/day. Ventricular function and the level of cardiac iron were assessed by echocardiography and magnetic resonance imaging at 0, 3, and 6 months.

Results:

The median age of the patients was 19 years (range 13–25 years). Four patients had severe left ventricular Grade III diastolic dysfunction and fourteen patients had Grade II diastolic dysfunction. The grade of left ventricular diastolic dysfunction was improved at 3 months after the carvedilol treatment. The Doppler parameters, including pulmonary vein atrial reversal velocity, pulmonary vein atrial reversal duration, and the difference of pulmonary vein atrial reversal and the mitral valve atrial contraction wave duration at 3 months after the carvedilol treatment, were significantly lower than these parameters before the treatment.

Conclusions:

Among patients with transfusion-dependent thalassemia who had left ventricular diastolic dysfunction without systolic dysfunction, treatment with carvedilol for 3 months was associated with improvement in Doppler parameters of left ventricular diastolic function. However, this finding and its clinical significance need to be confirmed in further double-blind controlled studies.

Glycosylated ferritin as an improved marker for post-transfusion iron overload

Red blood cell (RBC) transfusion is an effective therapy for anemia, but repeated transfusions may cause iron overload-related damage to various organs. Iron chelation therapy, now widely available for patients who have received transfusions, is expected to reduce organ damage even in patients who received many transfusions. Therefore, determining when to start iron chelation therapy is important. In guidelines for iron chelation therapy, the serum ferritin level has been widely accepted as a practical marker for estimating iron overload. However, guidelines recommend multiple measurements of serum ferritin, because levels often fluctuate. Here, we investigated the usefulness of glycosylated ferritin as a marker of iron overload using a cohort consisted of 103 patients who had a total ferritin value over 1000 ng/mL. We found that the volume of RBCs transfused was clearly associated with the glycosylated ferritin level. We also found that acute inflammation, as represented by C-reactive protein values, was associated with increased non-glycosylated ferritin and that patients with hematopoietic diseases had higher glycosylated ferritin levels, possibly because of repeated RBC transfusions. We thus conclude that glycosylated ferritin may be an improved marker for predicting iron overload status.

Early detection of ventricular dysfunction by tissue Doppler echocardiography related to cardiac iron overload in patients with thalassemia

Cardiac T2* MRI is used as a gold standard for cardiac iron quantification in patients with transfusion-dependent thalassemia (TDT). We hypothesized that left ventricular (LV) diastolic dysfunction would reflect the severity of iron overload and can serve as an early detection of cardiac iron deposits. A study was conducted on all patients with TDT. Hemoglobin, serum ferritin and non-transferrin bound iron, together with a complete echocardiography and cardiac T2* MRI, were performed on all patients. Seventy-seven patients with TDT were enrolled (median age 14 years). In the patient group with a mean serum ferritin of > 2500 ng/mL during the past 12 months, there were more patients with severe cardiac iron deposits than in the group with a mean serum ferritin of ≤ 2500 ng/mL. Diastolic dysfunction was absent in all patients with a serum ferritin of < 1000 ng/mL. All patients with cardiac T2* ≤ 20 ms had grade III LV diastolic dysfunction. However, twenty-one percent of patients with cardiac T2* > 20 ms had LV diastolic dysfunction. The differences observed in pulmonary vein atrial reversal duration and mitral A-wave (PVAR-MVA) duration ≥ - 1 ms and an E/E' ratio ≥ 11 were proven to be the associated factors with the cardiac T2* ≤ 20 ms. Increased PVAR-MVA duration and increased E/E' ratio reliably reflected a severe iron overload, according to a cardiac T2* in patients with TDT. LV diastolic dysfunction can occur prior to severe cardiac iron deposition. Tissue Doppler echocardiography has the potential for the early detection of cardiac involvement in patients with TDT .

Comparison of global strain values of myocardium in beta-thalassemia major patients with iron load using specific feature tracking in cardiac magnetic resonance imaging

Thalassemia defined a spectrum of diseases characterized by reduced or absent production of one of the globin chains of hemoglobin. High iron deposition in the myocardium may cause functional impairment even before any changes in left ventricular (LV) ejection fraction. These impairments may appear as changes in strain values. Early detection of myocardial dysfunction is essential for improving survival and preventing further complications. Therefore, this study aims to evaluate the cardiac strain patterns by Feature Tracking -Cardiac Magnetic Resonance Imaging (FT-CMR) method and their correlation with T2* values as a new parameter in determining myocardial iron overload (MIO). In this retrospective investigation, ninety-one patients with B-thalassemia major included from May 2016 to July 2019. Twenty-three healthy subjects, also incorporated as a control group. CMR used to evaluate ventricular volumes, LVEF, and the amount of myocardial T2*. Moreover, Global Longitudinal Strain (GLS), Global Circumferential Strain (GCS), and Global Radial Strain (GRS) were measured and analyzed in both rights and left ventricles. Correlations of cardiac T2* with GLS, GCS, and GRS were evaluated. The optimal cutoff value of GLS for prediction of cardiac T2* < 20 ms (as an indicator of inadequate chelation) calculated as well. There were significant correlations between cardiac T2* with LV GLS, LV GCS, and right ventricular GLS (p < 0.05 for each one). Moreover, a significant difference detected between the group of TM - MIO and TM + MIO and control group in terms of GLS (p < 0.001). The optimal cutoff value of GLS for prediction of cardiac T2* < 20 ms was at - 16.5% with sensitivity and specificity of 73% and 63%, respectively. Our study demonstrates that strain values measured by FT and myocardial T2* values are correlated. FT-CMR can be considered as an efficient tool for early detection of iron deposition and its effects on cardiac tissue so that proper and timely modification could have applied to chelation therapy.

A novel coumarin-chitosan fluorescent hydrogel for the selective identification of Fe2+ in aqueous systems

Functional fluorescent hydrogels were synthesized, and they can detect and adsorb Fe²⁺ in aqueous solution.

[Rare diseases recognizable from blood smears]

The examination of peripheral blood smears is not only essential for the differential diagnostics of hematological diseases but can also provide important indications for general internal diseases, infections, hereditary diseases and poisoning. By the systematic analysis of a blood smear for alterations to thrombocytes, erythrocytes and leukocytes, a blood smear investigation can make a decisive contribution to the formulation of a diagnosis. In this way evidence of rare diseases can also be gained when taking the corresponding clinical findings into consideration.

Fatal Cardiac Hemochromatosis in a Patient with Hereditary Spherocytosis

A 31-year-old man was admitted to our hospital with atrial tachycardia and cardiogenic shock. He had been diagnosed with hereditary spherocytosis (HS) during childhood, but he never received any red blood cell transfusions. Right ventricular endomyocardial biopsy revealed multiple myocardial hemosiderin deposits, and he was diagnosed with cardiac hemochromatosis. In addition to the iron deposition in the heart, the loss of myocyte and severe interstitial fibrosis were present. His cardiac function did not improve even after the cardioversion for atrial tachycardia, and he suffered from recurrent heart failure. Despite intensive medical treatment for heart failure and arrhythmias in combination with iron chelation therapy, he eventually died of progressive and refractory heart failure. Hemochromatosis is a systemic disorder characterized by the excessive deposition of iron in multiple organs. The occurrence of hemochromatosis in HS is extremely rare, and previous reports have shown that the coexistence of heterozygosity for the HFE gene mutation in HS patients causes excess iron storage. The prognosis is poor due to progressive congestive heart failure and refractory arrhythmias. Here we report a rare case of fatal cardiac hemochromatosis associated with HS. The possibility of cardiac hemochromatosis needs to be considered in cases of heart failure or arrhythmia in patients with HS.

Heart Rate Variability for Early Detection of Cardiac Iron Deposition in Patients with Transfusion-Dependent Thalassemia

Background

Iron overload cardiomyopathy remains the major cause of death in patients with transfusion-dependent thalassemia. Cardiac T2* magnetic resonance imaging is costly yet effective in detecting cardiac iron accumulation in the heart. Heart rate variability (HRV) has been used to evaluate cardiac autonomic function and is depressed in cases of thalassemia. We evaluated whether HRV could be used as an indicator for early identification of cardiac iron deposition.

Methods

One hundred and one patients with transfusion-dependent thalassemia were enrolled in this study. The correlation between recorded HRV and hemoglobin, non-transferrin bound iron (NTBI), serum ferritin and cardiac T2* were evaluated.

Results

The median age was 18 years (range 8–59 years). The patient group with a 5-year mean serum ferritin >5,000 ng/mL included significantly more homozygous β-thalassemia and splenectomized patients, had lower hemoglobin levels, and had more cardiac iron deposit than all other groups. Anemia strongly influenced all domains of HRV. After adjusting for anemia, neither serum ferritin nor NTBI impacted the HRV. However cardiac T2* was an independent predictor of HRV, even after adjusting for anemia. For receiver operative characteristic (ROC) curve analysis of cardiac T2* ≤20 ms, only mean ferritin in the last 12 months and the average of the standard deviation of all R-R intervals for all five-minute segments in the 24-hour recording were predictors for cardiac T2* ≤20 ms, with area under the ROC curve of 0.961 (p<0.0001) and 0.701 (p = 0.05), respectively.

Conclusions

Hemoglobin and cardiac T2* as significant predictors for HRV indicate that anemia and cardiac iron deposition result in cardiac autonomic imbalance. The mean ferritin in the last 12 months could be useful as the best indicator for further evaluation of cardiac risk. The ability of serum ferritin to predict cardiac risk is stronger than observed in other thalassemia cohorts. HRV might be a stronger predictor of cardiac iron in study populations with lower somatic iron burdens and greater prevalence of cardiac iron deposition.

The deferiprone and deferasirox combination is efficacious in iron overloaded patients with β-thalassemia major: A prospective, single center, open-label study

BACKGROUND

The high cost, coupled with the need for continuous infusion, renders Desferrioxamine (DFO), a non-feasible option for iron-chelation in a large majority of patients with β-thalassemia major in developing countries. Monotherapy with deferiprone (DFP) or deferasirox (DFX) may not always attain optimal control, particularly in heavily iron-loaded patients. Combination of DFP and DFX is a potential alternative.

PROCEDURE

A prospective, single-center, open-label, uncontrolled study was conducted to evaluate the safety and efficacy of the combination in patients with β-thalassemia major. Patients who had received either DFP or DFX for >1 year and a serum ferritin >2,000 μg/L were enrolled. Blood counts, liver/renal functions, and serum ferritin were monitored during the 1-year study period. Facilities for cardiac T2*-MRI were unavailable.

RESULTS

Thirty-six patients with a mean age of 13 ± 6.9 years (range: 4-29) and a ferritin of 6,768 ± 4,145 μg/L formed the study cohort. Eight (22%) patients had transient gastrointestinal adverse effects. DFX was discontinued in one patient for persistent abdominal pain/diarrhea. Eight (22%) had joint symptoms; DFP was discontinued in two. Four (11%) patients had elevation in AST/ALT levels, managed with temporary interruption of DFX. Nine (25%) had an inconsistent elevation of creatinine to >33% of baseline; no intervention was done. One had transient proteinuria. None had neutropenia. At the end of 1 year, the serum ferritin reduced by a mean value of 3,275.3 ± 618.2 μg/L (P < 0.001).

CONCLUSIONS

The oral combination was found to be safe, efficacious, and a feasible option in patients with suboptimal response to monotherapy.

Toward resolving the unsettled role of iron chelation therapy in myelodysplastic syndromes

Transfusion dependent low risk myelodysplastic syndromes (MDS) patients, eventually develop iron overload. Iron toxicity, via oxidative stress, can damage cellular components and impact organ function. In thalassemia major patients, iron chelation therapy lowered iron levels with recovery of cardiac and liver functions and significant improvement in survival. Several noncontrolled studies show inferior survival in MDS patients with iron overload, including an increase in transplant-related mortality and infection risk while iron chelation appears to improve survival in both lower risk MDS patients and in stem cell transplant settings. Collated data are presented on the pathophysiological impact of iron overload; measuring techniques and chelating agents' therapy positive impact on hematological status and overall survival are discussed. Although suggested by retrospective analyses, the lack of clear prospective data of the beneficial effects of iron chelation on morbidity and survival, the role of iron chelation therapy in MDS patients remains controversial.

Iron chelation and multiple sclerosis

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.