Structural and functional abnormalities in iron-depleted heart

Clinical Update in Heart Failure with Preserved Ejection Fraction

PURPOSE OF REVIEW

To review the most recent clinical trials and data regarding epidemiology, pathophysiology, diagnosis, and treatment of heart failure with preserved ejection fraction with an emphasis on the recent trends in cardiometabolic interventions.

RECENT FINDINGS

Heart failure with preserved ejection fraction makes up approximately half of overall heart failure and is associated with significant morbidity, mortality, and overall burden on the healthcare system. It is a complex, heterogenous syndrome and clinical trials, to this point, have not revealed quite as many effective treatment options when compared to heart failure with reduced ejection fraction. Nevertheless, there is an expanding amount of data insight into the pathogenesis of this disease and the potential for newer therapies and management strategies. Heart failure with preserved ejection fraction pathology has been found to be linked to abnormal energetics, myocyte hypertrophy, cell signaling, inflammation, ischemia, and fibrosis. These mechanisms also intricately overlap with the significant comorbidities often associated with heart failure with preserved ejection fraction including, but not limited to, atrial fibrillation, chronic kidney disease, hypertension, obesity and coronary artery disease. Treatment of this disease, therefore, should focus on the management and strict regulation of these comorbidities by pharmacologic and nonpharmacologic means. In this review, a clinical update is provided reviewing the most recent clinical trials and data regarding epidemiology, pathophysiology, diagnosis, and treatment of heart failure with preserved ejection fraction with an emphasis on the recent trend in cardiometabolic interventions.

Maternal hemoglobin and iron status in early pregnancy and childhood cardiac outcomes

BACKGROUND & AIMS

Dysregulation of iron homeostasis is associated with cardiac alterations in a sex-dependent manner in adults. It is unknown whether iron status during pregnancy has long-term impact on cardiovascular health, and if this association is influenced by sex. Therefore, this study aimed to evaluate sex-specific association between maternal iron status during early pregnancy and cardiac outcomes in children aged 10 years.

METHODS

In a population-based cohort study among 1972 mother-child pairs, hemoglobin and ferritin were measured in early pregnancy (<18 weeks) and categorized into anemia (hemoglobin<11 g/dL), elevated hemoglobin (hemoglobin≥13.2 g/dL), iron deficiency (ferritin<15 μg/L), and iron overload (ferritin>150 μg/L). At 10 years of age, cardiac MRI was performed to measure right and left cardiac outcomes of function (ventricular end-diastolic volume (RVEDV and LVEDV) and ejection fraction (RVEF and LVEF)), and structure (left ventricular mass (LVM), and left ventricular mass-to-volume ratio (LMVR)). Results are presented for boys and girls separately and models were adjusted for confounders and multiple testing.

RESULTS

In boys, one standard deviation score (SDS) increase in maternal hemoglobin was associated with lower RVEDV and LVEDV (difference (95%CI) -0.10 (-0.17, -0.03) SDS and -0.09 (-0.16, -0.03) SDS, respectively). In boys, maternal anemia, as compared to normal hemoglobin levels, was associated with higher LVEDV (difference 0.34 (0.10, 0.59) SDS). No associations were observed for other cardiac outcomes and for ferritin in boys. No associations were observed in girls.

CONCLUSION

In boys, dysregulated iron status during early pregnancy might permanently alter cardiovascular RVEDV and LVEDV function. Underlying mechanisms need further study.

Identification of TFRC as a biomarker for pulmonary arterial hypertension based on bioinformatics and experimental verification

BACKGROUND

Pulmonary arterial hypertension (PAH) is a life-threatening chronic cardiopulmonary disease. However, there is a paucity of studies that reflect the available biomarkers from separate gene expression profiles in PAH.

METHODS

The GSE131793 and GSE113439 datasets were combined for subsequent analyses, and batch effects were removed. Bioinformatic analysis was then performed to identify differentially expressed genes (DEGs). Weighted gene co-expression network analysis (WGCNA) and a protein-protein interaction (PPI) network analysis were then used to further filter the hub genes. Functional enrichment analysis of the intersection genes was performed using Gene Ontology (GO), Disease Ontology (DO), Kyoto encyclopedia of genes and genomes (KEGG) and gene set enrichment analysis (GSEA). The expression level and diagnostic value of hub gene expression in pulmonary arterial hypertension (PAH) patients were also analyzed in the validation datasets GSE53408 and GSE22356. In addition, target gene expression was validated in the lungs of a monocrotaline (MCT)-induced pulmonary hypertension (PH) rat model and in the serum of PAH patients.

RESULTS

A total of 914 differentially expressed genes (DEGs) were identified, with 722 upregulated and 192 downregulated genes. The key module relevant to PAH was selected using WGCNA. By combining the DEGs and the key module of WGCNA, 807 genes were selected. Furthermore, protein-protein interaction (PPI) network analysis identified HSP90AA1, CD8A, HIF1A, CXCL8, EPRS1, POLR2B, TFRC, and PTGS2 as hub genes. The GSE53408 and GSE22356 datasets were used to evaluate the expression of TFRC, which also showed robust diagnostic value. According to GSEA enrichment analysis, PAH-relevant biological functions and pathways were enriched in patients with high TFRC levels. Furthermore, TFRC expression was found to be upregulated in the lung tissues of our experimental PH rat model compared to those of the controls, and the same conclusion was reached in the serum of the PAH patients.

CONCLUSIONS

According to our bioinformatics analysis, the observed increase of TFRC in the lung tissue of human PAH patients, as indicated by transcriptomic data, is consistent with the alterations observed in PAH patients and rodent models. These data suggest that TFRC may serve as a potential biomarker for PAH.

Iron parameters analysis in dogs with myxomatous mitral valve disease

BACKGROUND

Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in small breed dogs. In contrast to human patients with heart failure (HF), iron deficiency (ID) prevalence in dogs with MMVD is weakly known. The study aimed to assess the usability of ID markers in serum and reticulocyte parameters from whole blood of dogs with MMVD to evaluate early ID symptoms.

RESULTS

Sixty-eight dogs (43 male and 25 female) were included in the study. MMVD dogs were assigned according to the 2019 ACVIM guidelines for groups B1 (n = 9), B2 (n = 10), C (n = 27) and D (n = 10). Groups were also combined into B1 and B2 as non-symptomatic HF and C with D as symptomatic HF. Healthy controls were 12 dogs. Serum iron concentration below the reference range in dogs with MMVD was 12.5%. Other ID indices, such as %SAT, UIBC, and TIBC were similar in the MMVD groups and healthy controls (p > 0.05 for all parameters). Statistical comparison between control group and 4 groups of different stages of MMVD showed that significant differences occur only in serum transferrin. The assessment of ferritin and soluble transferrin receptors using Western Blotting did not show differences between control (n = 7) and MMVD (n = 33) dogs. Study has shown positive correlation between ID parameters and echocardiographic indices such as LA/Ao and LVIDdN, and some biochemical parameters. A significant increase in reticulocytes percentage, assessed manually, was observed in the HF group of animals (p = 0.027) compared to the control group.

CONCLUSIONS

Studies have shown that ID parameters in serum are not significantly different in dogs with MMVD compared to healthy dogs. However, there is a clear correlation between atrial size and normalised left ventricular size to body size and some biochemical parameters, including ID parameters and therefore the severity of MMVD.

Role of Erythropoiesis-Stimulating Agents in Cardiovascular Protection in CKD Patients: Reappraisal of Their Impact and Mechanisms

Erythropoiesis-stimulating agents (ESAs) have markedly reduced the need for blood transfusion for renal anemia and are included in standard therapies for patients with chronic kidney disease (CKD). Various protective effects of ESAs on the cardiovascular system have been discovered through basic research, and the effects have received much attention because the rates of cardiovascular events and mortality are high in CKD patients. However, randomized clinical trials did not provide strong evidence that ESAs exert cardioprotection in humans, including CKD patients. It is difficult to assess the cardioprotective effects of ESAs in CKD patients through the clinical data that has been reported to date because the relationship between hemoglobin level rather than ESA dose and cardiovascular event rates was examined in most studies. Interestingly, recent studies using a rat model of CKD showed that the infarct size-limiting effect of an ESA was lost when its dose was increased to a level that normalized blood hemoglobin levels, suggesting that the optimal dose of an ESA for myocardial protection is less than the dose required to normalize hemoglobin levels. Furthermore, animal models of traditional coronary risk factors or comorbidities were resistant to the cardioprotective effects of ESAs because of interruptions in signal-mediated mechanisms downstream of erythropoietin receptors. In this review, we briefly discuss basic and clinical data on the impact of anemia on coronary and systemic circulation, the effects of CKD on the cardiovascular system, and the multiple pharmacological actions of ESAs to examine whether the ESAs that are prescribed for renal anemia exert any cardioprotection in patients with CKD.

Empagliflozin effects on iron metabolism as a possible mechanism for improved clinical outcomes in non-diabetic patients with systolic heart failure

Sodium-glucose co-transporter-2 (SGLT2) inhibitors improve clinical outcomes in patients with heart failure (HF), but mechanisms of action are incompletely understood. In the EMPA-TROPISM trial, empagliflozin reversed cardiac remodeling and increased physical capacity in stable non-diabetic patients with systolic HF. Here we explore, post hoc, whether treatment effects in this cohort, comprising patients who had a high prevalence of iron deficiency, were related to iron metabolism. Myocardial iron content estimated by cardiac magnetic resonance T2* quantification increased after initiation of empagliflozin but not placebo (treatment effect: P = 0.01). T2* changes significantly correlated with changes in left ventricular volumes, mass and ejection fraction, peak oxygen consumption and 6-minute walking distance; concomitant changes in red blood cell indices were consistent with augmented hematopoiesis. Exploratory causal mediation analysis findings indicated that changes in myocardial iron content after treatment with empagliflozin may be an important mechanism to explain its beneficial clinical effects in patients with HF.ClinicalTrials.gov: NCT03485222 .

Intravenous iron supplementation improves energy metabolism of exercising skeletal muscles without effect on either oxidative stress or inflammation in male patients with heart failure with reduced ejection fraction

BACKGROUND

Skeletal muscle dysfunction is a feature of heart failure (HF). Iron deficiency (ID) is prevalent in patients with HF associated with exercise intolerance and poor quality of life. Intravenous iron in iron deficient patients with HF has attenuated HF symptoms, however the pathomechanisms remain unclear. The aim of study was to assess whether intravenous iron supplementation as compared to placebo improves energy metabolism of skeletal muscles in patients with HF.

METHODS

Men with heart failure with reduced ejection fraction (HFrEF) and ID were randomised in 1:1 ratio to either intravenous ferric carboxymaltose (IV FCM) or placebo. In vivo reduction of lactates by exercising skeletal muscles of forearm was analyzed. A change in lactate production between week 0 and 24 was considered as a primary endpoint of the study.

RESULTS

There were two study arms: the placebo and the IV FCM (12 and 11 male patients with HFrEF). At baseline, there were no differences between these two study arms. IV FCM therapy as compared to placebo reduced the exertional production of lactates in exercising skeletal muscles. These effects were accompanied by a significant increase in both serum ferritin and transferrin saturation in the IV FCM arm which was not demonstrated in the placebo arm.

CONCLUSIONS

Intravenous iron supplementation in iron deficient men with HFrEF improves the functioning of skeletal muscles via an improvement in energy metabolism in exercising skeletal muscles, limiting the contribution of anaerobic reactions generating ATP as reflected by a lower in vivo lactate production in exercising muscles in patients with repleted iron stores.

Soluble Transferrin Receptor as Iron Deficiency Biomarker: Impact on Exercise Capacity in Heart Failure Patients

The soluble transferrin receptor (sTfR) is a marker of tissue iron status, which could indicate an increased iron demand at the tissue level. The impact of sTfR levels on functional capacity and quality of life (QoL) in non-anemic heart failure (HF) patients with otherwise normal systemic iron status has not been evaluated. We conducted an observational, prospective, cohort study of 1236 patients with chronic HF. We selected patients with normal hemoglobin levels and normal systemic iron status. Tissue iron deficiency (ID) was defined as levels of sTfR > 75th percentile (1.63 mg per L). The primary endpoints were the distance walked in the 6 min walking test (6MWT) and the overall summary score (OSS) of the Minnesota Living with Heart Failure Questionnaire (MLHFQ). The final study cohort consisted of 215 patients. Overall QoL was significantly worse (51 ± 27 vs. 39 ± 20, p-value = 0.006, respectively), and the 6 MWT distance was significantly worse in patients with tissue ID when compared to patients without tissue ID (206 ± 179 m vs. 314 ± 155, p-value < 0.0001, respectively). Higher sTfR levels, indicating increased iron demand, were associated with a shorter distance in the 6 MWT (standardized β = -0.249, p < 0.001) and a higher MLHFQ OSS (standardized β = 0.183, p-value = 0.008). In this study, we show that in patients with normal systemic iron parameters, higher levels of sTfR are strongly associated with an impaired submaximal exercise capacity and with worse QoL.

Pathophysiology and Treatment Opportunities of Iron Deficiency in Heart Failure: Is There a Need for Further Trials?

PURPOSE OF REVIEW

Iron deficiency (ID) complicates heart failure (HF) at different stages of the natural history of the disease; however, this frequent comorbidity is still not comprehensively understood and investigated in terms of pathophysiology. Intravenous iron therapy with ferric carboxymaltose (FCM) should be considered to improve the quality of life, exercise capacity, and symptoms in stable HF with ID, as well as to reduce HF hospitalizations in iron-deficient patients stabilized after an episode of acute HF. The therapy with intravenous iron, however, continues to generate important clinical questions for cardiologists.

RECENT FINDINGS

In the current paper, we discuss the class effect concept for intravenous iron formulations beyond FCM, based on the experiences of nephrologists who administer different intravenous iron formulations in advanced chronic kidney disease complicated with ID and anemia. Furthermore, we discuss the neutral effects of oral iron therapy in patients with HF, because there are still some reasons to further explore this route of supplementation. The different definitions of ID applied in HF studies and new doubts regarding possible interactions of intravenous iron with sodium-glucose co-transporter type 2 inhibitors are also emphasized. The experiences of other medical specializations may provide new information on how to optimally replenish iron in patients with HF and ID.

Iron Deficiency and Deranged Myocardial Energetics in Heart Failure

Among different pathomechanisms involved in the development of heart failure, adverse metabolic myocardial remodeling closely related to ineffective energy production, constitutes the fundamental feature of the disease and translates into further progression of both cardiac dysfunction and maladaptations occurring within other organs. Being the component of key enzymatic machineries, iron plays a vital role in energy generation and utilization, hence the interest in whether, by correcting systemic and/or cellular deficiency of this micronutrient, we can influence the energetic efficiency of tissues, including the heart. In this review we summarize current knowledge on disturbed energy metabolism in failing hearts as well as we analyze experimental evidence linking iron deficiency with deranged myocardial energetics.

Anemia and iron in internal medicine: an Italian survey and a review on iron intravenous therapy in medical patients

In Italy, Internal Medicine Units hospitalize approximately 1,300,000 patients, often elderly and comorbid. The prevalent diagnoses are respiratory diseases, heart failure, or pneumonia. As a matter of fact, anemia is probably underestimated in the compilation of the official discharge forms (SDO) according to ICD-9 diagnostic codes. We promoted a survey among the Members the Italian Scientific Society of Internal Medicine (FADOI) with the aim to investigate the prevalence of anemia and iron deficiency, over than certain aspects related to the therapeutic management of patients with anemia. Furthermore, we performed a review summarizing current evidence for iron intravenous therapy in these patients. According to the survey, anemia is present in around half of the patients hospitalized in Internal Medicine, and about a quarter of them shows iron metabolism alterations. In the evaluation of iron metabolism, the dosage of ferritin is the most requested exam, whereas transferrin saturation is less considered. By focusing on some categories of patients, the awareness of the usefulness of intravenous iron therapy in patients with heart failure seems to be sufficiently common (76% of physicians), while it seems lower (60%) in the management of patients with chronic kidney disease (CKD) and anemia. Finally, more than 75% of the physicians answered that, in their hospital, there are few outpatients’ offices or diagnostic pathways dedicated to patients with anemia. Anemia due to absolute or functional iron deficiency is particularly prevalent in Internal Medicine inpatients. For this reason, an accurate evaluation of iron profile and an adequate iron therapy is mandatory in these patients. Recent studies show that, in patients with heart failure, intravenous iron therapy is an effective way of improving patients’ health, regardless of the presence of anemia. Similarly, iron therapy results fundamental to optimize erythropoiesis-stimulating agent efficacy in patients with chronic renal failure. In the next future, other therapeutic aspects of intravenous iron therapy will be probably clarified by several interesting ongoing studies focused on these patients.

Myocardial Iron Deficiency and Mitochondrial Dysfunction in Advanced Heart Failure in Humans

Background

Myocardial iron deficiency (MID) in heart failure (HF) remains largely unexplored. We aim to establish defining criterion for MID, evaluate its pathophysiological role, and evaluate the applicability of monitoring it non‐invasively in human explanted hearts.

Methods and Results

Biventricular tissue iron levels were measured in both failing (n=138) and non‐failing control (NFC, n=46) explanted human hearts. Clinical phenotyping was complemented with comprehensive assessment of myocardial remodeling and mitochondrial functional profiles, including metabolic and oxidative stress. Myocardial iron status was further investigated by cardiac magnetic resonance imaging. Myocardial iron content in the left ventricle was lower in HF versus NFC (121.4 [88.1–150.3] versus 137.4 [109.2–165.9] μg/g dry weight), which was absent in the right ventricle. With a priori cutoff of 86.1 μg/g d.w. in left ventricle, we identified 23% of HF patients with MID (HF‐MID) associated with higher NYHA class and worsened left ventricle function. Respiratory chain and Krebs cycle enzymatic activities were suppressed and strongly correlated with depleted iron stores in HF‐MID hearts. Defenses against oxidative stress were severely impaired in association with worsened adverse remodeling in iron‐deficient hearts. Mechanistically, iron uptake pathways were impeded in HF‐MID including decreased translocation to the sarcolemma, while transmembrane fraction of ferroportin positively correlated with MID. Cardiac magnetic resonance with T2* effectively captured myocardial iron levels in failing hearts.

Conclusions

MID is highly prevalent in advanced human HF and exacerbates pathological remodeling in HF driven primarily by dysfunctional mitochondria and increased oxidative stress in the left ventricle. Cardiac magnetic resonance demonstrates clinical potential to non‐invasively monitor MID.

Identification of differentially expressed genes and pathways in diquat and paraquat poisoning using bioinformatics analysis

[Objective] In this study, differentially expressed genes (DEGs) and signaling pathways involved in diquat (DQ) and paraquat (PQ) poisoning were identified via bioinformatics analysis, in order to inform the development of novel clinical treatments. [Methods] Raw data from GSE153959 were downloaded from the Gene Expression Omnibus database. DEGs of the DQ vs. control (CON) and PQ vs. CON comparison groups were identified using R, and DEGs shared by the two groups were identified using TBtools. Subsequently, the shared DEGs were searched in the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, using the Database for Annotation, Visualization, and Integrated Discovery. A protein-protein interaction (PPI) network was constructed, and hub genes were identified using the cytoHubba plug-in in Cytoscape software. Finally, Circos and contrast plots showing the DEGs shared between mouse and human chromosomes were constructed using TBtools. [Results] Thirty- one DEGs shared by the DQ and PQ groups were identified. Enriched biological process terms included positive regulation of cell proliferation and translation. Enriched cellular component terms included extracellular region, intracellular membrane- bounded organelle and mitochondrion. Enriched molecular function terms included transcription factor activity and sequence-specific double-stranded DNA binding. Enriched KEGG pathways included the interleukin- 17 signaling pathway, tumor necrosis factor signaling pathway, and human T- cell leukemia virus 1 infection. The top ten hub genes in the PPI network were Ptgs2, Cxcl2, Csf2, Mmp13, Areg, Plaur, Fosl1, Ereg, Atf3, and Tfrc. Cxcl2, Csf2, and Atf3 played important roles in the mitogen- activated protein kinase signaling pathway. [Conclusions] These pathways and DEGs may serve as targets for gene therapy.

Short-Term Changes in Left and Right Ventricular Cardiac Magnetic Resonance Feature Tracking Strain Following Ferric Carboxymaltose in Patients With Heart Failure: A Substudy of the Myocardial-IRON Trial

Background

The mechanisms explaining the clinical benefits of ferric carboximaltose (FCM) in patients with heart failure, reduced or intermediate left ventricular ejection fraction, and iron deficiency remain not fully clarified. The Myocardial‐IRON trial showed short‐term cardiac magnetic resonance (CMR) changes suggesting myocardial iron repletion following administration of FCM but failed to find a significant increase in left ventricular ejection fraction in the whole sample. Conversely, the strain assessment could evaluate more specifically subtle changes in contractility. In this subanalysis, we aimed to evaluate the effect of FCM on the short‐term left and right ventricular CMR feature tracking derived strain.

Methods and Results

This is a post hoc subanalysis of the double‐blind, placebo‐controlled, randomized clinical trial that enrolled 53 ambulatory patients with heart failure and left ventricular ejection fraction <50%, and iron deficiency [Myocardial‐IRON trial (NCT03398681)]. Three‐dimensional left and 2‐dimensional right ventricular CMR tracking strain (longitudinal, circumferential, and radial) changes were evaluated before, 7 and 30 days after randomization using linear mixed‐effect analysis. The median (interquartile range) age of the sample was 73 years (65–78), and 40 (75.5%) were men. At baseline, there were no significant differences in CMR feature tracking strain parameters across both treatment arms. At 7 days, the only global 3‐dimensional left ventricular circumferential strain was significantly higher in the FCM treatment‐arm (difference: −1.6%, P=0.001). At 30 days, and compared with placebo, global 3‐dimensional left ventricular strain parameters significantly improved in those allocated to FCM treatment‐arm [longitudinal (difference: −2.3%, P<0.001), circumferential (difference: −2.5%, P<0.001), and radial (difference: 4.2%, P=0.002)]. Likewise, significant improvements in global right ventricular strain parameters were found in the active arm at 30 days (longitudinal [difference: −3.3%, P=0.010], circumferential [difference: −4.5%, P<0.001], and radial [difference: 4.5%, P=0.027]).

Conclusions

In patients with stable heart failure, left ventricular ejection fraction <50%, and iron deficiency, treatment with FCM was associated with short‐term improvements in left and right ventricular function assessed by CMR feature tracking derived strain parameters.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03398681.

Hemosiderin Accumulation in Liver Decreases Iron Availability in Tachycardia-Induced Porcine Congestive Heart Failure Model

Despite advances in the management of iron deficiency in heart failure (HF), the mechanisms underlying the effects of treatment remain to be established. Iron distribution and metabolism in HF pathogenesis need to be clarified. We used a porcine tachycardia-induced cardiomyopathy model to find out how HF development influences hepatic and myocardial iron storing, focusing on ferritin, the main iron storage protein. We found that cumulative liver congestion (due to the decrease of heart function) overwhelms its capacity to recycle iron from erythrocytes. As a consequence, iron is trapped in the liver as poorly mobilized hemosiderin. What is more, the ferritin-bound Fe³⁺ (reflecting bioavailable iron stores), and assembled ferritin (reflecting ability to store iron) are decreased in HF progression in the liver. We demonstrate that while HF pigs show iron deficiency indices, erythropoiesis is enhanced. Renin–angiotensin–aldosterone system activation and hepatic hepcidin suppression might indicate stress erythropoiesisinduced in HF. Furthermore, assembled ferritin increases but ferritin-bound Fe³⁺ is reduced in myocardium, indicating that a failing heart increases the iron storage reserve but iron deficiency leads to a drop in myocardial iron stores. Together, HF in pigs leads to down-regulated iron bioavailability and reduced hepatic iron storage making iron unavailable for systemic/cardiac needs.

Relationship between the Amount of Menstrual Flow and Cardiac Status in Women with Fontan Circulation

A high prevalence of heavy menstrual bleeding (HMB) has been reported in women with Fontan circulation. Cyanosis has been reported to contribute to HMB, and menstruation has been suggested to affect cardiac status in women with congenital heart disease. This study aimed to evaluate the relationship between the amount of menstrual flow and cardiac status in women with Fontan circulation.Twenty women who had undergone the Fontan procedure were prospectively investigated and the amount of their menstrual flow was evaluated using a questionnaire. Participants were divided into two groups-small and large menstrual bleeding groups-and their clinical data, including the results of hematological tests and echocardiographic findings, were evaluated.One (5%) woman showed primary amenorrhea. Eight of the remaining 19 (42%) women were included in the large menstrual bleeding group. Women with large menstrual bleeding showed a significantly higher hematocrit level (47.1% [36.2%-50.3%] versus 42.1% [35.3%-44.9%], P = 0.006) and longer QRS duration (106 [92-172] ms versus 88 [78-140] ms, P = 0.008), as well as a lower fractional area change (37.4% [35.6%-47.2%] versus 47.0% [38.2%-55.7%], P = 0.010) and global longitudinal strain (-10.5% [-14.9% to -6.6%] versus -13.9% [-20.5% to -7.8%], P = 0.041) of the dominant ventricle on echocardiography, than women with small bleeding.Erythrocytosis, longer QRS duration, and reduced ventricular function were related to increased menstrual bleeding in women with Fontan circulation. These functions may be interrelated with the amount of menstrual flow in such women.

Impact of intravenous ferric carboxymaltose on heart failure with preserved and reduced ejection fraction

AIMS

Heart failure (HF) is a proinflammatory disease often associated with the onset of iron deficiency (ID). ID alters mitochondrial function, reducing the generation of cellular energy in skeletal muscle and cardiomyocytes. This study aimed to analyse the response of patients with HF to intravenous iron administration according to the type of HF: preserved ejection fraction (HFpEF) or reduced ejection fraction (HFrEF).

METHODS AND RESULTS

We conducted a retrospective, single-centre study of 565 consecutive outpatients diagnosed with HF, recruited over 5 years, who were given intravenous ferric carboxymaltose (FCM) for the treatment of ID [defined as ferritin < 100 μg/L or ferritin 100-300 μg/L with transferrin saturation (TSAT) < 20%]. Clinical, laboratory, and echocardiographic parameters were analysed before and after administration. After FCM administration, overall ferritin, TSAT, and haemoglobin levels increased up to 5-fold, 1.6-fold, and 1.1-fold, respectively, relative to baseline values in HF patients with reduced and preserved ejection fraction (P < 0.0001), with a greater increase in ferritin and TSAT in HFpEF patients. The left ventricular ejection fraction of the overall series improved by 8 percentage points in both types of HF (from 40% to 48%, P < 0.0001). The percentage of patients with normalization of right ventricular function increased by 6.9 points (from 74.1% to 81%) in HFpEF patients and by 6.4 points (from 53% to 59.4%) in the HFrEF subgroup (P < 0.0001). New York Heart Association functional status slightly improved, from a median of 2.4 (interquartile range, IQR: 2-2.7) to 1.9 (IQR: 1.5-2.5; P < 0.0001) after FCM in both types of HF. No changes were noted in plasma levels of liver enzymes, creatinine, or natriuretic peptide (P > 0.05).

CONCLUSIONS

Intravenous iron administration appeared to improve ejection fraction and cardiac functional status in outpatients with ID and HF with both preserved and reduced ejection fraction.

Iron Deficiency in Heart Failure: Mechanisms and Pathophysiology

Iron is an essential micronutrient for a myriad of physiological processes in the body beyond erythropoiesis. Iron deficiency (ID) is a common comorbidity in patients with heart failure (HF), with a prevalence reaching up to 59% even in non-anaemic patients. ID impairs exercise capacity, reduces the quality of life, increases hospitalisation rate and mortality risk regardless of anaemia. Intravenously correcting ID has emerged as a promising treatment in HF as it has been shown to alleviate symptoms, improve quality of life and exercise capacity and reduce hospitalisations. However, the pathophysiology of ID in HF remains poorly characterised. Recognition of ID in HF triggered more research with the aim to explain how correcting ID improves HF status as well as the underlying causes of ID in the first place. In the past few years, significant progress has been made in understanding iron homeostasis by characterising the role of the iron-regulating hormone hepcidin, the effects of ID on skeletal and cardiac myocytes, kidneys and the immune system. In this review, we summarise the current knowledge and recent advances in the pathophysiology of ID in heart failure, the deleterious systemic and cellular consequences of ID.

Anemia: A Connection Between Heart Failure and Kidney Failure

Erythropoiesis-stimulating agents (ESAs) have improved the quality of life and reduced the need for transfusions in patients with chronic kidney disease. However, randomized trials showed no benefit but possible safety issues following high doses of ESAs given to reach normal hemoglobin levels. Iron therapy is used together with ESA; when given proactively, it may reduce the risk of mortality and cardiovascular events in hemodialysis patients. Recent trials also showed benefits of intravenous iron therapy in patients with heart failure. New drugs for correcting anemia may retain the present efficacy of ESAs as antianemic drugs and reduce cardiovascular risks.

Neurohormonal activation induces intracellular iron deficiency and mitochondrial dysfunction in cardiac cells

Background

Iron deficiency (ID) is common in patients with heart failure (HF) and is associated with poor outcomes, yet its role in the pathophysiology of HF is not well-defined. We sought to determine the consequences of HF neurohormonal activation in iron homeostasis and mitochondrial function in cardiac cells.

Methods

HF was induced in C57BL/6 mice by using isoproterenol osmotic pumps and embryonic rat heart-derived H9c2 cells were subsequently challenged with Angiotensin II and/or Norepinephrine. The expression of several genes and proteins related to intracellular iron metabolism were assessed by Real time-PCR and immunoblotting, respectively. The intracellular iron levels were also determined. Mitochondrial function was analyzed by studying the mitochondrial membrane potential, the accumulation of radical oxygen species (ROS) and the adenosine triphosphate (ATP) production.

Results

Hearts from isoproterenol-stimulated mice showed a decreased in both mRNA and protein levels of iron regulatory proteins, transferrin receptor 1, ferroportin 1 and hepcidin compared to control mice. Furthermore, mitoferrin 2 and mitochondrial ferritin were also downregulated in the hearts from HF mice. Similar data regarding these key iron regulatory molecules were found in the H9c2 cells challenged with neurohormonal stimuli. Accordingly, a depletion of intracellular iron levels was found in the stimulated cells compared to non-stimulated cells, as well as in the hearts from the isoproterenol-induced HF mice. Finally, neurohormonal activation impaired mitochondrial function as indicated by the accumulation of ROS, the impaired mitochondrial membrane potential and the decrease in the ATP levels in the cardiac cells.

Conclusions

HF characteristic neurohormonal activation induced changes in the regulation of key molecules involved in iron homeostasis, reduced intracellular iron levels and impaired mitochondrial function. The current results suggest that iron could be involved in the pathophysiology of HF.

Role of iron homeostasis in the heart : Heart failure, cardiomyopathy, and ischemia-reperfusion injury

As an essential trace mineral in mammals and the second most abundant metal in the Earth's crust, iron acts as a double-edged sword in humans. Iron plays important beneficial roles in numerous biological processes ranging from deoxyribonucleic acid biosynthesis and protein function to cell cycle progression. However, iron metabolism disruption leads to widespread tissue degeneration and organ dysfunction. An increasing number of studies have focused on iron regulation pathways and have explored the relationship between iron and cardiovascular diseases. Ferroptosis, an iron-dependent form of programmed cell death, was first described in cancer cells and has recently been linked to heart diseases, including cardiac ischemia-reperfusion injury and doxorubicin-induced myocardiopathy. Here, we summarize recent advances in our understanding of iron homeostasis and heart diseases and discuss potential relationships between ferroptosis and cardiac ischemia-reperfusion injury and cardiomyopathy.

Primary Human Cardiomyocytes and Cardiofibroblasts Treated with Sera from Myocarditis Patients Exhibit an Increased Iron Demand and Complex Changes in the Gene Expression

Cardiac fibroblasts and cardiomyocytes are the main cells involved in the pathophysiology of myocarditis (MCD). These cells are especially sensitive to changes in iron homeostasis, which is extremely important for the optimal maintenance of crucial cellular processes. However, the exact role of iron status in the pathophysiology of MCD remains unknown. We cultured primary human cardiomyocytes (hCM) and cardiofibroblasts (hCF) with sera from acute MCD patients and healthy controls to mimic the effects of systemic inflammation on these cells. Next, we performed an initial small-scale (n = 3 per group) RNA sequencing experiment to investigate the global cellular response to the exposure on sera. In both cell lines, transcriptomic data analysis revealed many alterations in gene expression, which are related to disturbed canonical pathways and the progression of cardiac diseases. Moreover, hCM exhibited changes in the iron homeostasis pathway. To further investigate these alterations in sera-treated cells, we performed a larger-scale (n = 10 for controls, n = 18 for MCD) follow-up study and evaluated the expression of genes involved in iron metabolism. In both cell lines, we demonstrated an increased expression of transferrin receptor 1 (TFR1) and ferritin in MCD serum-treated cells as compared to controls, suggesting increased iron demand. Furthermore, we related TFR1 expression with the clinical profile of patients and showed that greater iron demand in sera-treated cells was associated with higher inflammation score (interleukin 6 (IL-6), C-reactive protein (CRP)) and advanced neurohormonal activation (NT-proBNP) in patients. Collectively, our data suggest that the malfunctioning of cardiomyocytes and cardiofibroblasts in the course of MCD might be related to alterations in the iron homeostasis.

Iron deficiency as therapeutic target in heart failure: a translational approach

Heart failure (HF) is a potentially debilitating condition, with a prognosis comparable to many forms of cancer. It is often complicated by anemia and iron deficiency (ID), which have been shown to even further harm patients' functional status and hospitalization risk. Iron is a cellular micronutrient that is essential for oxygen uptake and transportation, as well as mitochondrial energy production. Iron is crucially involved in electrochemical stability, maintenance of structure, and contractility of cardiomyocytes. There is mounting evidence that ID indeed hampers the homeostasis of these properties. Animal model and stem cell research has verified these findings on the cellular level, while clinical trials that treat ID in HF patients have shown promising results in improving real patient outcomes, as electromechanically compromised cardiomyocytes translate to HF exacerbations and arrhythmias in patients. In this article, we review our current knowledge on the role of iron in cardiac muscle cells, the contribution of ID to anemia and HF pathophysiology and the capacity of IV iron therapy to ameliorate the patients' arrhythmogenic profile, quality of life, and prognosis.

Iron Deficiency in Pulmonary Arterial Hypertension: A Deep Dive into the Mechanisms

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease that is caused by the progressive occlusion of the distal pulmonary arteries, eventually leading to right heart failure and death. Almost 40% of patients with PAH are iron deficient. Although widely studied, the mechanisms linking between PAH and iron deficiency remain unclear. Here we review the mechanisms regulating iron homeostasis and the preclinical and clinical data available on iron deficiency in PAH. Then we discuss the potential implications of iron deficiency on the development and management of PAH.

ESA, Iron Therapy and New Drugs: Are There New Perspectives in the Treatment of Anaemia?

Anemia is a well-known consequence of chronic kidney disease (CKD); it is mainly due to a relative insufficiency of erythropoietin synthesis by the failing kidneys. Over the years, the combination of erythropoiesis stimulating agents (ESA) and iron has become the standard of care of anemia. All ESAs effectively increase hemoglobin (Hb) levels in a substantial percentage of patients. However, in the last decade, their use has been surrounded by safety issues in increased cardiovascular risk, especially when used at high doses in inflamed and hyporesponsive patients. This has led to the definition of a more cautious Hb target. Iron deficiency is very frequent in CKD patients, with a higher frequency in non-dialysis patients. Traditionally, iron supplementation is mostly used as supportive therapy for anemia control. However, the concept is growing that intravenous iron therapy per se could be beneficial in the presence of heart failure. A new class of drugs, prolyl hydroxylase domain (PHD) inhibitors (PHD inhibitors) is becoming available for the treatment of anemia in CKD patients. Theoretically, these agents have a number of advantages, the main ones being that of stimulating the synthesis of endogenous erythropoietin and increasing iron availability. The impact of their future use in clinical practice is still to be defined. Another possible strategy could be targeting serum hepcidin and its related pathways. This possibility is fascinating from the scientific point of view, but at present its development phase is still far from clinical application.

High soluble transferrin receptor in patients with heart failure: a measure of iron deficiency and a strong predictor of mortality

AIMS

Iron deficiency (ID) is frequent in heart failure (HF), linked with exercise intolerance and poor prognosis. Intravenous iron repletion improves clinical status in HF patients with left ventricular ejection fraction (LVEF) ≤45%. However, uncertainty exists about the accuracy of serum biomarkers in diagnosing ID. The aims of this study were (i) to identify the iron biomarker with the greatest accuracy for the diagnosis of ID in bone marrow in patients with ischaemic HF, and (ii) to establish the prevalence of ID using this biomarker and its prognostic value in HF patients.

METHODS AND RESULTS

Bone marrow was stained for iron in 30 patients with ischaemic HF with LVEF ≤45% and 10 healthy controls, and ID was diagnosed for 0-1 grades (Gale scale). A total of 791 patients with HF with LVEF ≤45% were prospectively followed up for 3 years. Serum ferritin, transferrin saturation, soluble transferrin receptor (sTfR) were assessed as iron biomarkers. Most patients with HF (n = 25, 83%) had ID in bone marrow, but none of the controls (P < 0.001). Serum sTfR had the best accuracy in predicting ID in bone marrow (area under the curve 0.920, 95% confidence interval 0.761-0.987, for cut-off 1.25 mg/L sensitivity 84%, specificity 100%). Serum sTfR was ≥1.25 mg/L in 47% of HF patients, in 56% and 46% of anaemics and non-anaemics, respectively (P < 0.05). The reclassification methods revealed that serum sTfR significantly added the prognostic value to the baseline prognostic model, and to the greater extent than plasma N-terminal pro B-type natriuretic peptide. Based on internal derivation and validation procedures, serum sTfR ≥1.41 mg/L was the optimal threshold for predicting 3-year mortality, independent of other established variables.

CONCLUSIONS

High serum sTfR accurately reflects depleted iron stores in bone marrow in patients with HF, and identifies those with a high 3-year mortality.

Short-term changes in left and right systolic function following ferric carboxymaltose: a substudy of the Myocardial-IRON trial

AIMS

The mechanisms underlying the beneficial effect of ferric carboxymaltose (FCM) in patients with heart failure (HF) and iron deficiency (ID) have not been completely characterized. The Myocardial-IRON trial was a double-blind, randomized trial that evaluated myocardial iron repletion following FCM vs. placebo in 53 patients with HF and ID. In this post hoc analysis, we evaluated whether treatment with FCM was associated with cardiac magnetic resonance changes in left and right ventricular function (LVEF and RVEF, respectively) at different points of systolic dysfunction.

METHODS AND RESULTS

We included patients from the Myocardial-IRON trial with left and right ventricular systolic dysfunction (LVSD and RVSD, respectively) at enrolment. Linear mixed regression models were used to evaluate changes at 7 and 30 days on LVEF and RVEF at cardiac magnetic resonance. At enrolment, 27 (50.9%) and 38 (71.7%) patients had LVEF < 40% (LVSD1 ) or <45% (LVSD2 ), respectively, and 10 (18.9%) and 17 (32.1%) patients had RVEF < 45% (RVSD1 ) or <51% in women and <52% in men (RVSD2) , respectively. Treatment with FCM was associated with a significant improvement in LVEF at 30 days (LVSD1 : Δ2.3%, P < 0.001; LVSD2 : Δ4.1, P = 0.014). FCM was also associated with a significant and early improvement in RVEF at 7 days (RVSD1 : Δ6.9%, P = 0.003; RVSD2 : Δ3.2%, P = 0.003) that persisted at 30 days (RVSD1 : Δ8.1%, P < 0.001; RVSD2 : Δ4.7%, P < 0.001).

CONCLUSIONS

In patients with HF and systolic dysfunction with ID, FCM was associated with short-term improvement in LVEF and, especially, in RVEF.

Effects of a Cumulative, Suboptimal Supply of Multiple Trace Elements in Mice: Trace Element Status, Genomic Stability, Inflammation, and Epigenetics

SCOPE

Trace element (TE) deficiencies often occur accumulated, as nutritional intake is inadequate for several TEs, concurrently. Therefore, the impact of a suboptimal supply of iron, zinc, copper, iodine, and selenium on the TE status, health parameters, epigenetics, and genomic stability in mice are studied.

METHODS AND RESULTS

Male mice receive reduced or adequate amounts of TEs for 9 weeks. The TE status is analyzed mass-spectrometrically in serum and different tissues. Furthermore, gene and protein expression of TE biomarkers are assessed with focus on liver. Iron concentrations are most sensitive toward a reduced supply indicated by increased serum transferrin levels and altered hepatic expression of iron-related genes. Reduced TE supply results in smaller weight gain but higher spleen and heart weights. Additionally, inflammatory mediators in serum and liver are increased together with hepatic genomic instability. However, global DNA (hydroxy)methylation is unaffected by the TE modulation.

CONCLUSION

Despite homeostatic regulation of most TEs in response to a low intake, this condition still has substantial effects on health parameters. It appears that the liver and immune system react particularly sensitive toward changes in TE intake. The reduced Fe status might be the primary driver for the observed effects.

Noninvasive Imaging Estimation of Myocardial Iron Repletion Following Administration of Intravenous Iron: The Myocardial-IRON Trial

Background

Intravenous ferric carboxymaltose (FCM) improves symptoms, functional capacity, and quality of life in heart failure and iron deficiency. The mechanisms underlying these effects are not fully understood. The aim of this study was to examine changes in myocardial iron content after FCM administration in patients with heart failure and iron deficiency using cardiac magnetic resonance.

Methods and Results

Fifty‐three stable heart failure and iron deficiency patients were randomly assigned 1:1 to receive intravenous FCM or placebo in a multicenter, double‐blind study. T2* and T1 mapping cardiac magnetic resonance sequences, noninvasive surrogates of intramyocardial iron, were evaluated before and 7 and 30 days after randomization using linear mixed regression analysis. Results are presented as least‐square means with 95% CI. The primary end point was the change in T2* and T1 mapping at 7 and 30 days. Median age was 73 (65–78) years, with N‐terminal pro‐B‐type natriuretic peptide, ferritin, and transferrin saturation medians of 1690 pg/mL (1010–2828), 63 ng/mL (22–114), and 15.7% (11.0–19.2), respectively. Baseline T2* and T1 mapping values did not significantly differ across treatment arms. On day 7, both T2* and T1 mapping (ms) were significantly lower in the FCM arm (36.6 [34.6–38.7] versus 40 [38–42.1], P=0.025; 1061 [1051–1072] versus 1085 [1074–1095], P=0.001, respectively). A similar reduction was found at 30 days for T2* (36.3 [34.1–38.5] versus 41.1 [38.9–43.4], P=0.003), but not for T1 mapping (1075 [1065–1085] versus 1079 [1069–1089], P=0.577).

Conclusions

In patients with heart failure and iron deficiency, FCM administration was associated with changes in the T2* and T1 mapping cardiac magnetic resonance sequences, indicative of myocardial iron repletion.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT03398681.

Rationale and design of the AFFIRM-AHF trial: a randomised, double-blind, placebo-controlled trial comparing the effect of intravenous ferric carboxymaltose on hospitalisations and mortality in iron-deficient patients admitted for acute heart failure

AIMS

Iron deficiency (ID) is a common co-morbidity in heart failure (HF), associated with impaired functional capacity, poor quality of life and increased morbidity and mortality. Treatment with intravenous (i.v.) ferric carboxymaltose (FCM) has shown improvements in functional capacity, symptoms and quality of life in stable HF patients with reduced ejection fraction. The effect of i.v. iron supplementation on morbidity and mortality in patients hospitalised for acute HF (AHF) and who have ID has yet to be established. The objective of the present article is to present the rationale and design of the AFFIRM-AHF trial (ClinicalTrials.gov NCT02937454) which will investigate the effect of i.v. FCM (vs. placebo) on recurrent HF hospitalisations and cardiovascular (CV) mortality in iron-deficient patients hospitalised for AHF.

METHODS

AFFIRM-AHF is a multicentre, randomised (1:1), double-blind, placebo-controlled trial which recruited 1100 patients hospitalised for AHF and who had iron deficiency ID defined as serum ferritin <100 ng/mL or 100-299 ng/mL if transferrin saturation <20%. Eligible patients were randomised (1:1) to either i.v. FCM or placebo and received the first dose of study treatment just prior to discharge for the index hospitalisation. Patients will be followed for 52 weeks. The primary outcome is the composite of recurrent HF hospitalisations and CV mortality. The main secondary outcomes include the composite of recurrent CV hospitalisations and CV mortality, recurrent HF hospitalisations and safety-related outcomes.

CONCLUSION

The AFFIRM-AHF trial will evaluate, compared to placebo, the effect of i.v. FCM on morbidity and mortality in iron-deficient patients hospitalised for AHF.

[Anaemia and iron deficiency in chronic heart failure patients]

Tis review focused on prevalence of anemia and iron defciency (ID) in CHF and their effect on the course and prognosis of this condition. Based on evaluation of numerous laboratory data defnitions of anemia and ID were suggested. Specifcally, a diagnostic value of measuring serum iron, serum ferritin, transferrin saturation, total iron-binding capacity, and concentration of soluble transferrin receptors was discussed. Te review highlighted the importance of measuring bone marrow iron, which is rarely used in everyday clinical practice even though this test is considered a «gold standard» of ID diagnosis. Te review provided an insight into pathogenetic mechanisms of ID in CHF including insufcient iron supply, role of inflammation, erythropoietin, RAS, and effects of some pharmacological therapies. Te authors described physiological consequences of ID and anemia, activation of hemodynamic and non-hemodynamic compensatory mechanisms, which develop in response to anemia and not infrequently aggravate CHF. Special atention was paid to current approaches to treatment of anemia and ID in CHF, including a discussion of efcacy and safety of oral and intravenous dosage forms of iron and hemopoiesis stimulators.