Iron Overload Cardiomyopathy in Clinical Practice

Short communication: high cellular iron levels are associated with increased HIV infection and replication

HIV is a pandemic disease, and many cellular and systemic factors are known to alter its infectivity and replication. Earlier studies had suggested that anemia is common in HIV-infected patients; however, higher iron was also observed in AIDS patients prior to the introduction of antiretroviral therapy (ART). Therefore, the relationship between iron and viral infection is not well delineated. To address this issue, we altered the levels of cellular iron in primary CD4(+) T cells and showed that higher iron is associated with increased HIV infection and replication. In addition, HIV infection alone leads to increased cellular iron, and several ART drugs increase cellular iron independent of HIV infection. Finally, HIV infection is associated with increased serum iron in HIV-positive patients regardless of treatment with ART. These results establish a relationship between iron and HIV infection and suggest that iron homeostasis may be a viable therapeutic target for HIV.

Increasing prevalence of thalassemia in America: Implications for primary care

Thalassemia, once a rarity in the United States, is increasingly encountered in clinical practice due to shifts in immigration. Early carrier screening in at-risk populations can help clinicians implement genetic counseling and prevent new cases. Chronic transfusions are the mainstay of therapy for patients with severe thalassemia (beta thalassemia major), and are used intermittently in individuals with milder forms of thalassemia (Hb H/H Constant Spring disease and beta thalassemia intermedia). Iron overload is a major source of morbidity and mortality in individuals with transfusion and non-transfusion-dependent thalassemia, necessitating iron chelation therapy. Iron overload contributes to increased risk of cirrhosis, heart failure, and endocrinopathies, while ineffective erythropoiesis and hemolysis contribute to multiple complications, including splenomegaly, extramedullary hematopoiesis, pulmonary hypertension, and thrombosis. An understanding of the importance of carrier screening, complications, monitoring, and management strategies, coupled with collaboration with a hematologist with thalassemia expertise, is essential to reduce the morbidity and mortality in patients with thalassemia.

Appraising cardiac dysfunction in liver transplantation: an ongoing challenge

End-stage liver disease (ESLD) is a multisystemic disease that adversely and mutually aggravates other organs such as the heart. Cardiac dysfunction in ESLD encompasses a spectrum of disease that could be aggravated, precipitated or be occurring hand-in-hand with coexisting aetiological factors precipitating cirrhosis. Additionally and more complexly, liver transplantation, the curative modality of ESLD, is responsible for additional intra- and postoperative short- and long-term cardiac morbidity. The phenotypic distinction of the different forms of cardiac dysfunction in ESLD albeit important prognostically and therapeutically is not allowed by the current societal recommendations, due to conceptual, and methodological limitations in the appraisal of cardiac function and structure in ESLD and in designing studies that are based on this appraisal. This review comprehensively discusses the spectrum of cardiac dysfunction in ESLD, discusses the limitations of the current appraisal of cardiac dysfunction in ESLD, and proposes a hypothetical approach for studying cardiac dysfunction in liver transplant candidates.

Cardiac failure after liver transplantation requiring a biventricular assist device

Increased hepatic iron load in extrahepatic organs of cirrhotic patients with and without hereditary hemochromatosis portends a poorer long term prognosis after liver transplant. Hepatic as well as nonhepatic iron overload is associated with increased infectious and postoperative complications, including cardiac dysfunction. In this case report, we describe a cirrhotic patient with alpha 1 antitrypsin deficiency and nonhereditary hemochromatosis (non-HFE) that developed cardiogenic shock requiring mechanical circulatory support for twenty days after liver transplant. Upon further investigation, she was found to have significant iron deposition in both the liver and heart biopsies. Her heart regained complete and sustained recovery following ten days of mechanical biventricular support. This case highlights the importance of preoperatively recognizing extrahepatic iron deposition in patients referred for liver transplantation irrespective of etiology of liver disease as this may prevent postoperative complications.

Iron metabolism in transplantation

Recipient's iron status is an important determinant of clinical outcome in transplantation medicine. This review addresses iron metabolism in solid organ transplantation, where the role of iron as a mediator of ischemia-reperfusion injury, as an immune-modulatory element, and as a determinant of organ and graft function is discussed. Although iron chelators reduce ischemia-reperfusion injury in cell and animal models, these benefits have not yet been implemented into clinical practice. Iron deficiency and iron overload are associated with reduced immune activation, whose molecular mechanisms are reviewed in detail. Furthermore, iron overload and hyperferritinemia are associated with poor prognosis in end-stage organ failure in patients awaiting kidney, or liver transplantation. This negative prognostic impact of iron overload appears to persist after transplantation, which highlights the need for optimizing iron management before and after solid organ transplantation. In contrast, iron deficiency and anemia are also associated with poor prognosis in patients with end-stage heart failure. Intravenous iron supplementation should be managed carefully because parenterally induced iron overload could persist after successful transplantation. In conclusion, current evidence shows that iron overload and iron deficiency are important risk factors before and after solid organ transplantation. Iron status should therefore be actively managed in patients on the waiting list and after transplantation.

Endothelial function, antioxidant status and vascular compliance in newly diagnosed HFE C282Y homozygotes

PURPOSE

This pilot study was aimed to establish techniques for assessing and observing trends in endothelial function, antioxidant status and vascular compliance in newly diagnosed HFE haemochromatosis during the first year of venesection.

PATIENTS/METHODS

Untreated newly diagnosed HFE haemochromatosis patients were tested for baseline liver function, iron indices, lipid profile, markers of endothelial function, anti-oxidant status and vascular compliance. Following baseline assessment, subjects attended at 6-weeks and at 3, 6, 9 and 12-months for follow-up studies.

RESULTS

Ten patients were recruited (M=8, F=2, mean age=51 years). Venesection significantly increased high density lipoproteins at 12-months (1.25 mmol/L vs. 1.37 mmol/L, p=0.01). However, venesection did not significantly affect lipid hydroperoxides, intracellular and vascular cell adhesion molecules or high sensitivity C-reactive protein (0.57 μmol/L vs. 0.51 μmol/L, p=0.45, 427.4 ng/ml vs. 307.22 ng/ml, p=0.54, 517.70 ng/ml vs. 377.50 ng/ml, p=0.51 and 290.75 μg/dL vs. 224.26 μg/dL, p=0.25). There was also no significant effect of venesection on anti-oxidant status or pulse wave velocity (9.65 m/s vs. 8.74 m/s, p=0.34).

CONCLUSIONS

Venesection significantly reduced high density lipoproteins but was not associated with significant changes in endothelial function, anti-oxidant status or vascular compliance. Larger studies using this established methodology are required to clarify this relationship further.

The relationship of initial transferrin saturation to cardiovascular parameters and outcomes in patients initiating dialysis

BACKGROUND

The prognostic importance of anemia for cardiovascular (CV) events and mortality has been extensively investigated. However, little is known about the impact of transferrin saturation (TSAT), a marker reflecting the availability of iron for erythropoiesis, on clinical outcome in dialysis patients.

METHODS

A total of 879 anemic incident dialysis patients were recruited from the Clinical Research Center for End-Stage Renal Disease in Korea and were divided into 3 groups according to baseline TSAT of ≤20%, 20-40%, and >40%.

RESULTS

There were no differences in hemoglobin levels and the proportion of patients on erythropoiesis-stimulating agents or iron supplements among the 3 groups. During a mean follow-up duration of 19.3 months, 51 (5.8%) patients died. CV composite (11.71 vs. 5.55 events/100 patient-years, P = 0.001) and all-cause mortality rates (5.38 vs. 2.31 events/100 patient-years, P = 0.016) were significantly higher in patients with TSAT ≤20% compared to those with TSAT 20-40% (reference group). Cox regression analysis revealed that patients with TSAT ≤20% had 1.62- and 2.19-fold higher risks for CV composite outcome (P = 0.046) and all-cause mortality (P = 0.030). Moreover, TSAT ≤20% was significantly associated with left ventricular hypertrophy [odds ratio (OR)  = 1.46], high-sensitivity C-reactive protein ≥3 mg/dL (OR = 2.09), N-terminal pro B-type natriuretic peptide ≥10000 pg/mL (OR  = 2.04), and troponin-T≥0.1 ng/mL (OR  = 2.02), on logistic regression analysis.

CONCLUSIONS

Low TSAT was a significant independent risk factor for adverse clinical outcome in incident dialysis patients with anemia, which may be partly attributed to cardiac dysfunction and inflammation.

The pathophysiological relationship and clinical significance of left atrial function and left ventricular diastolic dysfunction in β-thalassemia major

Iron deposition in combination with inflammatory and immunogenetic factors is involved in the pathophysiology of cardiac dysfunction in β-thalassemia major. We investigated the mechanical and endocrine function of the left atrium and ventricle to identify early signs of dysfunction. We studied 90 patients (mean age: 29 ± 11 years) with β-thalassemia and normal left ventricular function and 90 age and sex-matched healthy controls. Patients and controls underwent a thorough cardiac echocardiographic study and measurements of the b-type (NT-proBNP) and atrial natriuretic peptides (proANP). Patients underwent 24-hr Holter recordings for arrhythmia monitoring. In the patient group, atria were affected early during the course of the disease, prior to diastolic and systolic left ventricular dysfunction. The E/E'ratio (E Doppler mitral fast inflow to the corresponding tissue Doppler E) continually increased with age (P < 0.05) and reached levels indicating left ventricular diastolic dysfunction (E/E' > 15) in the third decade whereas indexes of active and passive atrial function decreased gradually throughout life. In controls, the E/E' ratio continually increased with age but with later (fifth decade) appearance of diastolic dysfunction and a compensatory increase in atrial active function. Both natriuretic peptides were significantly increased in patients compared to controls (558 ± 141 and 2,580 ± 1,830 fmol/mL for NT-proBNP and proANP versus 332 ± 106 and 1,331 ± 1,134 fmol/mL, respectively). Atrial fibrillation was found in a subgroup of 23 (26%) patients, older in age with mild diastolic function and enlarged, depressed atria. In conclusion, atrial mechanical depression seems to be a very early sign of cardiac damage. It may become echocardiographically evident even before diastolic and systolic dysfunction and is associated to supraventricular arrhythmias.

Monogenic diseases that can be cured by liver transplantation

While the prevalence of most diseases caused by single-gene mutations is low and defines them as rare conditions, all together, monogenic diseases account for approximately 10 in every 1000 births according to the World Health Organisation. Orthotopic liver transplantation (LT) could offer a therapeutic option in monogenic diseases in two ways: by substituting for an injured liver or by supplying a tissue that can replace a mutant protein. In this respect, LT may be regarded as the correction of a disease at the level of the dysfunctional protein. Monogenic diseases that involve the liver represent a heterogeneous group of disorders. In conditions associated with predominant liver parenchymal damage (i.e., genetic cholestatic disorders, Wilson's disease, hereditary hemochromatosis, tyrosinemia, α1 antitrypsin deficiency), hepatic complications are the major source of morbidity and LT not only replaces a dysfunctional liver but also corrects the genetic defect and effectively cures the disease. A second group includes liver-based genetic disorders characterised by an architecturally near-normal liver (urea cycle disorders, Crigler-Najjar syndrome, familial amyloid polyneuropathy, primary hyperoxaluria type 1, atypical haemolytic uremic syndrome-1). In these defects, extrahepatic complications are the main source of morbidity and mortality while liver function is relatively preserved. Combined transplantation of other organs may be required, and other surgical techniques, such as domino and auxiliary liver transplantation, have been attempted. In a third group of monogenic diseases, the underlying genetic defect is expressed at a systemic level and liver involvement is just one of the clinical manifestations. In these conditions, LT might only be partially curative since the abnormal phenotype is maintained by extrahepatic synthesis of the toxic metabolites (i.e., methylmalonic acidemia, propionic acidemia). This review focuses on principles of diagnosis, management and LT results in both paediatric and adult populations of selected liver-based monogenic diseases, which represent examples of different transplantation strategies, driven by the understanding of the expression of the underlying genetic defect.

Cardiovascular function and treatment in β-thalassemia major: a consensus statement from the American Heart Association

This aim of this statement is to report an expert consensus on the diagnosis and treatment of cardiac dysfunction in β-thalassemia major (TM). This consensus statement does not cover other hemoglobinopathies, including thalassemia intermedia and sickle cell anemia, in which a different spectrum of cardiovascular complications is typical. There are considerable uncertainties in this field, with a few randomized controlled trials relating to treatment of chronic myocardial siderosis but none relating to treatment of acute heart failure. The principles of diagnosis and treatment of cardiac iron loading in TM are directly relevant to other iron-overload conditions, including in particular Diamond-Blackfan anemia, sideroblastic anemia, and hereditary hemochromatosis. Heart failure is the most common cause of death in TM and primarily results from cardiac iron accumulation. The diagnosis of ventricular dysfunction in TM patients differs from that in nonanemic patients because of the cardiovascular adaptation to chronic anemia in non-cardiac-loaded TM patients, which includes resting tachycardia, low blood pressure, enlarged end-diastolic volume, high ejection fraction, and high cardiac output. Chronic anemia also leads to background symptomatology such as dyspnea, which can mask the clinical diagnosis of cardiac dysfunction. Central to early identification of cardiac iron overload in TM is the estimation of cardiac iron by cardiac T2* magnetic resonance. Cardiac T2* <10 ms is the most important predictor of development of heart failure. Serum ferritin and liver iron concentration are not adequate surrogates for cardiac iron measurement. Assessment of cardiac function by noninvasive techniques can also be valuable clinically, but serial measurements to establish trends are usually required because interpretation of single absolute values is complicated by the abnormal cardiovascular hemodynamics in TM and measurement imprecision. Acute decompensated heart failure is a medical emergency and requires urgent consultation with a center with expertise in its management. The first principle of management of acute heart failure is control of cardiac toxicity related to free iron by urgent commencement of a continuous, uninterrupted infusion of high-dose intravenous deferoxamine, augmented by oral deferiprone. Considerable care is required to not exacerbate cardiovascular problems from overuse of diuretics or inotropes because of the unusual loading conditions in TM. The current knowledge on the efficacy of removal of cardiac iron by the 3 commercially available iron chelators is summarized for cardiac iron overload without overt cardiac dysfunction. Evidence from well-conducted randomized controlled trials shows superior efficacy of deferiprone versus deferoxamine, the superiority of combined deferiprone with deferoxamine versus deferoxamine alone, and the equivalence of deferasirox versus deferoxamine.

Serum ferritin in thalassemia intermedia

Serum ferritin is a useful monitoring tool for iron overload in thalassemia major. In resource poor settings access to modalities for assessment of iron overload are limited. This study was undertaken to assess the efficiency and usefulness of serum ferritin level in thalassemia intermedia (TI) patients. This was a cross sectional observational study. Seventy seven TI patients attending the pediatric hematology clinic were included. Fasting blood sample was taken from each patient in iron free vials for iron studies. Serum ferritin was estimated by immunometric enzyme immunoassay using Orgentec GmbH kits. Mean age of patients evaluated was 10.9 ± 5.03 (3-26) years. The mean age at diagnosis was 4.21 ± 2.3 (0.8-11) years. Mean serum ferritin was 486.54 ± 640.0 ng/ml (15-4,554). Thirty two (41.5 %) patients had a ferritin value of ≥500 ng/ml. Nine patients had a serum ferritin of ≥1,000 ng/ml. Three of the subjects with a ferritin >1,000 ng/ml had never received a blood transfusion (BT) and in the other six, the number of BTs ranged from 1 to 8. Serum ferritin did not correlate with age, total number of BTs splenectomy status or BT in last one year (p > 0.05). In 41.5 % of TI patients, serum ferritin was ≥500 ng/ml. Age, BT and splenectomized status did not affect ferritin level. We postulate interplay of other biological factors like HFE gene mutation, ferroportin, etc. to contribute to ferritin level and hence iron load in TI patients. Ferritin can possibly be used as screening and monitoring tool for iron load in TI patients when other modalities to assess iron overload are not easily available.

Assessment and management of iron overload in β-thalassaemia major patients during the 21st century: a real-life experience from the Italian WEBTHAL project

We conducted a cross-sectional study on 924 β-thalassaemia major patients (mean age 30·1 years) treated at nine Italian centres using the WEBTHAL software, to evaluate real-life application of iron overload assessment and management standards. Serum ferritin <2500 ng/ml was a risk factor for never having liver iron concentration (LIC) measurement, while absence of cardiac disease and siderosis were risk factors for a delay in LIC measurement >2 years. Patients who never had a cardiac MRI (CMR) T2* measurement were <18 years, had iron intake ≤0·4 mg/kg per day, or a serum ferritin <2500 ng/ml. A history of normal CMR T2* was the main risk factor for a delay in subsequent assessment of >2 years. Deferoxamine (22·8%) was more commonly used in patients with Hepatitis C Virus or high serum creatinine. Deferiprone (20·6%) was less commonly prescribed in patients with elevated alanine aminotransferase; while a deferoxamine + deferiprone combination (17·9%) was more commonly used in patients with serum ferritin >2500 ng/ml or CMR T2* <20 ms. Deferasirox (38·3%) was more commonly prescribed in patients <18 years, but less commonly used in those with heart disease or high iron intake. These observations largely echoed guidelines at the time, although some practices are expected to change in light of evolving evidence.

Prevalence of iron overload complications among patients with b-thalassemia major treated at Dubai Thalassemia Centre

BACKGROUND AND OBJECTIVES

Authors and team members of the Dubai Thalassemia Centre obtained data on the prevalence of iron overload complications among patients with b-thalassemia major (b-TM) and compared it to international data to improve patient care and evaluate the effectiveness of earlier used treatment modalities. The information obtained is also expected to be useful in genetic counseling.

DESIGN AND SETTING

Cross-sectional study of all living transfusion-dependent b-TM patients registered at the Thalassemia Centre in Dubai, United Arab Emirates, until the end of 2007 (n=382).

PATIENTS AND METHODS

Diagnosis of TM was based on clinical history and laboratory confirmation by hemoglobin electrophoresis and DNA testing. All were uniformly treated with desferrioxamine and monitored by serial serum ferritin. results: The mean (SD) age of patients was 15.4 (7.6) years, with 50.5% males. Mean (SD) serum ferritin was 2597.2 (1976.8) micro g/L. The frequency of iron overload complications were as follows: hypogonadism (n=99, 52.7%), hypoparathyroidism (n=40, 10.5%), diabetes mellitus (n=40, 10.5%), hypothyroidism (n=24, 6.5%) and cardiomyopathies (n=7, 1.8%). Hypogonadism was the most common endocrine abnormality in our study and other reported series. However, cardiomyopathies were less prevalent among our patients with higher rates of diabetes and hypoparathyroidism compared to rates reported internationally. Females had statistically significant lower serum ferritin (2530.8 (1931.2), P < .05) with a lower cardiomyopathies rate.

CONCLUSION

Iron overload related complications among our patients with thalassemia major were different from those reported internationally. Studying the genetic status of patients from our area may uncover the underlying genetic modifiers of iron overload mediated organs injury.

An autopsy case of secondary iron-overload cardiomyopathy

A woman over 70 years of age presented with anemia and appetite loss. She had no history of blood transfusions, although she had been receiving iron infusions for anemia for seven years. She had an elevated serum ferritin level (7,951 ng/mL) one month before admission. Abdominal computed tomography showed increased hepatic density and echocardiography showed normal heart valves and heart-wall motion. The patient eventually experienced atrial tachycardia and atrial fibrillation and died of heart failure. An autopsy revealed iron deposits in the liver, pancreas, adrenal glands, thyroid gland, gastric mucosa and myocardium. Iron-overload cardiomyopathy was diagnosed based on the iron deposits, myocardial disarray and interstitial fibrosis.

Left ventricular noncompaction in patients with β-thalassemia: uncovering a previously unrecognized abnormality

Left ventricular noncompaction (LVNC) is a rare cardiomyopathy with potentially serious outcomes. It results in multiple and excessive trabeculations, deep intertrabecular recesses, and a thickened ventricular myocardium with two distinct layers, compacted and noncompacted. The condition is most commonly congenital; however, acquired forms have also been described. A recent report of LVNC detected in a β-thalassemia twin suggested an association with cardiac siderosis. In a cross-sectional study of 135 transfusion-dependent patients with β-thalassemia (130 major and 5 intermedia, mean age 29.6 ± 7.7 years, 49.6% males) presenting for cardiac iron assessment by magnetic resonance imaging (MRI), we evaluated the prevalence and risk factors for LVNC. None of the patients had neuromuscular or congenital heart disease. Eighteen patients (13.3%; 95% confidence interval [CI] = 8.6-20.1) fulfilled the preassigned strict criteria for LVNC on cardiac MRI. There were no statistically significant differences between patients with and without LVNC with respect to demographics; hemoglobin levels; splenectomy status; systemic, hepatic, and cardiac iron overload indices; hepatic disease and infection studies; or iron chelator type. Patients with LVNC were more likely to have heart failure (adjusted odds ratio = 1.77; 95% CI = 0.29-10.89); although with high uncertainty. Patients with β-thalassemia have a higher prevalence of LVNC than normal individuals. As this finding could not be explained by conventional risk factors in this patient population, further investigation of the underlying mechanisms of LVNC is warranted. This remains crucial for an entity with adverse cardiac outcomes, especially in patients with β-thalassemia where cardiac disease remains a primary cause of mortality.

Fe²⁺ block and permeation of CaV3.1 (α1G) T-type calcium channels: candidate mechanism for non-transferrin-mediated Fe²⁺ influx

Iron is a biologically essential metal, but excess iron can cause damage to the cardiovascular and nervous systems. We examined the effects of extracellular Fe²⁺ on permeation and gating of Ca(V)3.1 channels stably transfected in HEK293 cells, by using whole-cell recording. Precautions were taken to maintain iron in the Fe²⁺ state (e.g., use of extracellular ascorbate). With the use of instantaneous I-V currents (measured after strong depolarization) to isolate the effects on permeation, extracellular Fe²⁺ rapidly blocked currents with 2 mM extracellular Ca²⁺ in a voltage-dependent manner, as described by a Woodhull model with K(D) = 2.5 mM at 0 mV and apparent electrical distance δ = 0.17. Extracellular Fe²⁺ also shifted activation to more-depolarized voltages (by ∼10 mV with 1.8 mM extracellular Fe²⁺) somewhat more strongly than did extracellular Ca²⁺ or Mg²⁺, which is consistent with a Gouy-Chapman-Stern model with surface charge density σ = 1 e(-)/98 Ų and K(Fe) = 4.5 M⁻¹ for extracellular Fe²⁺. In the absence of extracellular Ca²⁺ (and with extracellular Na⁺ replaced by TEA), Fe²⁺ carried detectable, whole-cell, inward currents at millimolar concentrations (73 ± 7 pA at -60 mV with 10 mM extracellular Fe²⁺). With a two-site/three-barrier Eyring model for permeation of Ca(V)3.1 channels, we estimated a transport rate for Fe²⁺ of ∼20 ions/s for each open channel at -60 mV and pH 7.2, with 1 μM extracellular Fe²⁺ (with 2 mM extracellular Ca²⁺). Because Ca(V)3.1 channels exhibit a significant "window current" at that voltage (open probability, ∼1%), Ca(V)3.1 channels represent a likely pathway for Fe²⁺ entry into cells with clinically relevant concentrations of extracellular Fe²⁺.

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

Iron overload is one of the major causes of morbidity and death in patients undergoing chronic transfusion therapy. Furthermore, excessive iron accumulation in the heart may result in impaired left ventricular dysfunction. With accurate monitoring techniques and treatment regimens, progression of heart complications can be followed, and their natural history changed. Iron chelation therapy is the mainstay of prevention and reversal of myocardial iron overload. Despite recent appraisals of general chelating strategies, the management of iron chelation in chronically transfused patients with a focus on the heart has not been extensively assessed. New studies published in the past couple of years have provided important new data in this topic and therefore this review summarizes the major studies that examined the removal of iron from the heart with the iron chelators: deferoxamine, deferiprone, and deferasirox. Since chronically transfused patients and their cardiac clinical presentations vary widely, this review tries to identify--with each drug--the precise scenarios evaluated, linking patients' baseline characteristics, clinical setting, and drug intake and dosing. Ultimately, by stratifying patients according to their cardiac iron overload status and ventricular function, this review identifies possible approaches for the initial treatment and follow-up of transfusion-related cardiac iron overload.