Role of Iron Deficiency in Heart Failure-Clinical and Treatment Approach: An Overview

BACKGROUND

The association of chronic heart failure (CHF) and iron deficiency (ID) with or without anemia is frequently encountered in current medical practice and has a negative prognostic impact, worsening patients' exercise capacity and increasing hospitalization costs. Moreover, anemia is common in patients with chronic kidney disease (CKD) and CHF, an association known as cardio-renal anemia syndrome (CRAS) possessing a significantly increased risk of death.

AIM

This review aims to provide an illustrative survey on the impact of ID in CHF patients-based on physiopathological traits, clinical features, and the correlation between functional and absolute ID with CHF-and the benefit of iron supplementation in CHF.

METHOD

We selected the most recent publications with important scientific content covering the association of CHF and ID with or without anemia.

DISCUSSIONS

An intricate physiopathological interplay is described in these patients-decrease in erythropoietin levels, activation of the renin-angiotensin-aldosterone system, systemic inflammation, and increases in hepcidin levels. These mechanisms amplify anemia, CHF, and CKD severity and worsen patients' outcomes.

CONCLUSIONS

Anemia is frequently encountered in CHF and represents a negative prognostic factor. Data from randomized controlled trials have underlined the administration of intravenous iron therapy (ferric carboxymaltose) as the only viable treatment option, with beneficial effects on quality of life and exercise capacity in patients with ID and systolic heart failure.

Practical Guidance for Diagnosing and Treating Iron Deficiency in Patients with Heart Failure: Why, Who and How?

Iron deficiency (ID) is a comorbid condition frequently seen in patients with heart failure (HF). Iron has an important role in the transport of oxygen, and is also essential for skeletal and cardiac muscle, which depend on iron for oxygen storage and cellular energy production. Thus, ID per se, even without anaemia, can be harmful. In patients with HF, ID is associated with a poorer quality of life (QoL) and exercise capacity, and a higher risk of hospitalisations and mortality, even in the absence of anaemia. Despite its negative clinical consequences, ID remains under-recognised. However, it is easily diagnosed and managed, and the recently revised 2021 European Society of Cardiology (ESC) guidelines on HF provide specific recommendations for its diagnosis and treatment. Prospective randomised controlled trials in patients with symptomatic HF with reduced ejection fraction (HFrEF) show that correction of ID using intravenous iron (principally ferric carboxymaltose [FCM]) provides improvements in symptoms of HF, exercise capacity and QoL, and a recent trial demonstrated that FCM therapy following hospitalisation due to acute decompensated HF reduced the risk of subsequent HF hospitalisations. This review provides a summary of the epidemiology and pathophysiology of ID in HFrEF, and practical guidance on screening, diagnosing, and treating ID.

A protocol for prospective observational study to determine if non-anaemic iron deficiency worsens postoperative outcome in adult patients undergoing elective cardiac surgery: the IDOCS study

Background

Pre-operative anaemia has been associated independently with worse outcomes after cardiac surgery in adults and is often caused by absolute or functional iron deficiency. Iron deficiency is a continuum ending with anaemia, and therefore it is plausible that pre-operative early or ‘non-anaemic’ iron deficiency may also be associated with worse outcomes in patients undergoing cardiac surgery.

Methods

We have designed a prospective, observational study to determine if there is an association between non-anaemic iron deficiency and worse outcomes after cardiac surgery in adults. Patients without anaemia undergoing elective cardiac surgery will be allocated to an iron-deficient and an iron-replete group based on standard pre-operative blood tests (ferritin, transferrin saturation and C-reactive protein). The primary outcome is days alive and at home on postoperative day 30. The key secondary outcomes are days alive and at home on postoperative day 90 and readmission to acute care. Other secondary outcomes include health-related quality of life questionnaires, quality of postoperative recovery, postoperative complications, changes in haemoglobin concentration, and requirement for allogeneic blood products. The planned study sample size is 240 patients per group, which has 83% power to detect a median difference of 1.25 days in the primary outcome. The study commenced in March 2018, and recently completed recruitment, with data audit and cleaning ongoing.

Discussion

This study will be conducted using a rigorous, prospective observational design; it will provide peak bodies and clinicians with high-quality evidence concerning the associations between non-anaemic iron deficiency and patient-centred outcomes after elective cardiac surgery. Our primary and key secondary outcomes are known to have great importance to clinicians and patients alike and align with the recommendations of the StEP-COMPAC group for outcomes in prospective peri-operative research. The definition used for iron deficiency accounts for both absolute and functional iron deficiency and make use of standard pre-operative blood tests to make this determination, easing the transition of results into clinical practice. The study will be conducted in two relatively high-volume centres in a single high-income country. This limits the generalisability of study results to similar centres.

Trial registration

Australian and New Zealand Clinical Trials Registry (ACTRN12618000185268). Registered 5 February 2018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13741-022-00239-2.

Composite Biomarkers for Assessing Frailty Status in Stable Older Adults With Cardiovascular Disease

Background: The relationship between frailty status and laboratory measurements in cardiovascular disease (CVD) remains unclear. We investigated which laboratory measurements indicated frailty in stable older CVD patients.

Methods and Results: One-hundred thirty-eight stable older CVD patients were evaluated by laboratory measurements, with frailty assessed using the Kihon Checklist (KCL). Laboratory measurements were compared between frail and non-frail groups. Across the entire cohort, mean age was 81.7 years, mean left ventricular ejection fraction was 57.8%, and mean plasma B-type natriuretic peptide was 182 pg/mL. KCL scores were used to divide patients into non-frail (n=43; KCL <8) and frail (n=95; KCL ≥8) groups. Serum iron was significantly lower in the frail than non-frail group (mean [±SD] 61.2±30.3 vs. 89.5±26.1 μg/dL, respectively; P<0.001). Blood urea nitrogen (BUN; 27.3±16.5 vs. 19.7±8.2 mg/dL; P=0.013) and C-reactive protein (CRP; 1.05±1.99 vs. 0.15±0.21 mg/dL; P=0.004) were significantly higher in the frail than non-frail group. Multivariate analysis revealed that serum iron, CRP, and BUN were significant independent predictors of frailty (β=−0.069, 0.917, and 0.086, respectively).

Conclusions: Frailty status was significantly associated with iron, CRP, and BUN in stable older CVD patients. Composite biomarkers (inflammation, iron deficiency, and renal perfusion) may be useful for assessing frailty in these patients.

Expression of Iron Metabolism Proteins in Patients with Chronic Heart Failure

In heart failure, iron deficiency is a common comorbid disease that negatively influences exercise tolerance, number of hospitalizations and mortality rate, and this is why iron iv supplementation is recommended. Little is known about the changes in iron-related proteins in the human HF myocardium. The purpose of this study was to assess iron-related proteins in non-failing (NFH) vs. failing (FH) human myocardium. The study group consisted of 58 explanted FHs; control consisted of 31 NFHs unsuitable for transplantation. Myocardial proteins expressions: divalent metal transporter (DMT-1); L-type calcium channel (L-CH); transferrin receptors (TfR-1/TfR-2); ferritins: heavy (FT-H) or light (FT-L) chain, mitochondrial (FT-MT); ferroportin (FPN), regulatory factors and oxidative stress marker: 4-hydroxynonenal (4-HNE). In FH, the expression in almost all proteins responsible for iron transport: DMT-1, TfR-1, L-CH, except TfR-2, and storage: FT-H/-L/-MT were reduced, with no changes in FPN. Moreover, 4-HNE expression (pg/mg; NFH 10.6 ± 8.4 vs. FH 55.7 ± 33.7; p < 0.0001) in FH was increased. HNE-4 significantly correlated with DMT-1 (r = −0.377, p = 0.036), L-CH (r = −0.571, p = 0.001), FT-H (r = −0.379, p = 0.036), also FPN (r = 0.422, p = 0.018). Reducing iron-gathering proteins and elevated oxidative stress in failing hearts is very unfavorable for myocardiocytes. It should be taken into consideration before treatment with drugs or supplements that elevate free oxygen radicals in the heart.

Acute heart failure and iron deficiency: a prospective, multicentre, observational study

Aims

The prevalence and the natural course of iron deficiency (ID) in acute heart failure (AHF) are still unclear. We investigated the prevalence of ID in unselected patients admitted with AHF on admission, at discharge and up to 3 months thereafter.

Methods and results

In this prospective, multicentre, observational study, 742 patients admitted with AHF were enrolled. The main study outcome was the percentage of patients with ID (ferritin <100 μg/L = absolute ID or ferritin 100–299 μg/L and transferrin saturation <20% = functional ID) at admission (T0), after clinical stabilization prior to discharge (T1), and 10 ± 6 weeks after discharge (T2). At T0, ID was present in 71.8% of the patients (44.1% absolute and 27.7% functional ID). At T1 and T2, ID was present in 56.4% (32.4% absolute and 24% functional ID) and 50.3% (36.8% absolute and 13.5% functional ID), respectively. Absolute ID persisted from T0 to T2 in 66% of the patients, while functional ID resolved in 56% of the patients. Ferritin (median [interquartile range] 124 μg/L [56–247] to 150 μg/L [73–277]), transferrin saturation (15% [10–20] to 18% [12–27]), and iron levels (9 μmol/L [6–13] to 11 μmol/L [8–16]) increased significantly (all P < 0.001) from T0 to T1. Transferrin saturation (to 21% [15–29]) and iron levels (to 13 μmol/L [9–17]) also increased significantly (both P < 0.01) from T1 to T2 without iron supplementation.

Conclusions

Iron deficiency is highly prevalent in patients with AHF, but resolves during treatment in some patients, even without iron supplementation. Absolute ID is more likely to persist over time, whereas functional ID often resolves during treatment of AHF, representing probably a reduced iron availability rather than a true deficiency.

Trace elements in patients with aortic valve sclerosis

Background:

Aortic valve sclerosis (AVSc) is defined as the thickening and calcification of aortic valve cusps, in the absence of obstruction of ventricular outflow. AVSc is linked with a clear imbalance in some trace elements.

Aims:

The objective of this study was to investigate the relationship between AVSc and serum levels of iron (Fe), zinc (Zn), selenium (Se), and copper (Cu). Additionally, this research aimed to explore the clinical significance of human serum zinc, selenium, copper, and iron concentrations as a potential new biomarker for AVSc patients and to clarify the pathophysiological role in individuals at risk of developing AVSc.

Patients and methods:

The study included 40 subjects with AVSc (25% male and 75% female) who were compared with a healthy control group with the same gender ratio. AVSc was based on comprehensive echocardiographic assessments. Blood samples were taken and Zn and Cu concentrations were determined through the use of atomic absorption spectroscopy. Se was measured using an inductively coupled plasma mass spectrometry device and Fe was measured using a Beckman Coulter instrument.

Results:

There was a significant difference in the prevalence of diabetes, blood pressure levels, and body mass index between the patients and the healthy subjects (p < 0.05). The differences between the serum Fe, Se, and Cu levels of the AVSc patients and the healthy subjects (p > 0.05) were recorded. The serum Zn of AVSc patients when compared was significantly lower compared with that of the control group (p < 0.01).

Conclusion:

Patients with AVSc had an imbalance in some of the trace elements in their blood. The patient group’s valves had higher serum Cu levels and lower serum Se, Zn, and Fe concentrations compared with the healthy group’s valves. In the valve patients as compared, AVSc had a high prevalence of obesity, hypertension, and diabetes.

Anemia and Management of Heart Failure Patients

Anemia is common in heart failure with preserved and reduced ejection fraction. It is independently associated with poor functional status, hospitalization, and reduced survival. Its etiology is complex and multifactorial. Hemodynamic and nonhemodynamic compensatory mechanisms have been discussed as a response to chronic anemia. Whether anemia is a risk marker of advanced disease or a risk factor for progressive heart failure is debated. Current guidelines recommend a diagnostic workup as a part of standard management. Studies investigating intravenous iron administration reported beneficial effects on clinical outcomes. This article reviews current information on anemia.

Hypoferremia is Associated With Increased Hospitalization and Oxygen Demand in COVID-19 Patients

Iron metabolism might play a crucial role in cytokine release syndrome in COVID-19 patients. Therefore, we assessed iron metabolism markers in COVID-19 patients for their ability to predict disease severity. COVID-19 patients referred to the Heidelberg University Hospital were retrospectively analyzed. Patients were divided into outpatients (cohort A, n = 204), inpatients (cohort B, n = 81), and outpatients later admitted to hospital because of health deterioration (cohort C, n = 23). Iron metabolism parameters were severely altered in patients of cohort B and C compared to cohort A. In multivariate regression analysis including age, gender, CRP and iron-related parameters only serum iron and ferritin were significantly associated with hospitalization. ROC analysis revealed an AUC for serum iron of 0.894 and an iron concentration <6 μmol/l as the best cutoff-point predicting hospitalization with a sensitivity of 94.7% and a specificity of 67.9%. When stratifying inpatients in a low- and high oxygen demand group serum iron levels differed significantly between these two groups and showed a high negative correlation with the inflammatory parameters IL-6, procalcitonin, and CRP. Unexpectedly, serum iron levels poorly correlate with hepcidin. We conclude that measurement of serum iron can help predicting the severity of COVID-19. The differences in serum iron availability observed between the low and high oxygen demand group suggest that disturbed iron metabolism likely plays a causal role in the pathophysiology leading to lung injury.

Iron deficiency in 78 805 people admitted with heart failure across England: a retrospective cohort study

Objectives

Iron deficiency (ID), with or without anaemia (IDA), is an important comorbidity in people with chronic heart failure (HF), but the prevalence and significance in those admitted with HF is uncertain. We assessed the prevalence of ID or IDA in adults (age ≥21 years) hospitalised with a primary diagnosis of HF, and examined key metrics associated with these secondary diagnoses.

Methods

A retrospective cohort study of Hospital Episode Statistics describing all adults admitted to National Health Service (NHS) hospitals across England from April 2015 through March 2016 with primary diagnostic discharge coding as HF, with or without subsidiary coding for ID/IDA.

Results

78 805 adults were admitted to 177 NHS hospitals with primary coding as HF: 26 530 (33.7%) with secondary coding for ID/IDA, and 52 275 (66.3%) without. Proportionately more patients coded ID/IDA were admitted as emergencies (94.8% vs 87.6%; p<0.0001). Tending to be older and female, they required a longer length of stay (15.8 vs 12.2 days; p<0.0001), with higher per capita costs (£3623 vs £2918; p<0.0001), the cumulative excess expenditure being £21.5 million. HF-related (8.2% vs 5.2%; p<0.0001) and all-cause readmission rates (25.8% vs 17.7%; p<0.05) at ≤30 days were greater in those with ID/IDA against those without, and they manifested a small but statistically significant increased inpatient mortality (13.5% v 12.9%; p=0.009).

Conclusions

For adults admitted to hospitals in England, principally with acute HF, ID/IDA are significant comorbidities and associated with adverse outcomes, both for affected individuals, and the health economy.

Anemia in heart failure - from guidelines to controversies and challenges

Anemia associated with heart failure is a frequent condition, which may lead to heart function deterioration by the activation of neuro-hormonal mechanisms. Therefore, a vicious circle is present in the relationship of heart failure and anemia. The consequence is reflected upon the patients’ survival, quality of life, and hospital readmissions. Anemia and iron deficiency should be correctly diagnosed and treated in patients with heart failure. The etiology is multifactorial but certainly not fully understood. There is data suggesting that the following factors can cause anemia alone or in combination: iron deficiency, inflammation, erythropoietin levels, prescribed medication, hemodilution, and medullar dysfunction. There is data suggesting the association among iron deficiency, inflammation, erythropoietin levels, prescribed medication, hemodilution, and medullar dysfunction. The main pathophysiologic mechanisms, with the strongest evidence-based medicine data, are iron deficiency and inflammation. In clinical practice, the etiology of anemia needs thorough evaluation for determining the best possible therapeutic course. In this context, we must correctly treat the patients’ diseases; according with the current guidelines we have now only one intravenous iron drug. This paper is focused on data about anemia in heart failure, from prevalence to optimal treatment, controversies, and challenges.

Iron Therapy in Heart Failure: Ready for Primetime?

There is an increasing awareness of the prevalence of iron deficiency (ID) in patients with heart failure (HF) and its contributory role in the morbidity and mortality of HF. It is important to note that many HF patients have ID without being anaemic, hence it is vital to screen for ID even in patients with haemoglobin within the normal laboratory range. This review summarises the pathophysiology and epidemiology of ID in HF before discussing the evidence for iron replacement therapy in HF patients. Finally, it discusses the ongoing large outcome trials evaluating iron replacement in HF.

Understanding Iron Deficiency in Heart Failure: Clinical Significance and Management

Iron deficiency (ID) has been increasingly recognized as an important co-morbidity associated with heart failure (HF). ID significantly impairs exercise tolerance and is an independent predictor of poor outcomes in people with HF irrespective of their anemic status. Diagnosis of ID in people with HF is often missed and therefore routine screening for ID is necessary for these patients. IV iron repletion has been recommended in HF treatment guidelines to improve symptoms and exercise capacity. People with ID and HF who are treated with IV iron have an improved quality of life, better 6-minute walk test results and New York Heart Association functional class. The effect of iron therapy on re-hospitalization and mortality rates in people with HF remains unclear. Large-dose oral iron treatment has been found to be ineffective in improving symptoms in people with HF. This review summarizes the current knowledge on prevalence, clinical relevance, and the molecular mechanism of ID in patients with chronic HF and the available evidence for the use of parenteral iron therapy.

Anaemia, but not iron deficiency, is associated with clinical symptoms and quality of life in patients with severe heart failure and palliative home care: A substudy of the PREFER trial

BACKGROUND

To explore the relationships between anaemia or iron deficiency (ID) and symptoms, quality of life (QoL), morbidity, and mortality.

METHODS

A post-hoc, non-prespecified, explorative substudy of the prospective randomized PREFER trial. One centre study of outpatients with severe HF and palliative need managed with advanced home care. Associations between anaemia, ID, and the Edmonton Symptom Assessment Scale (ESAS), Euro QoL (EQ-5D), Kansas City Cardiomyopathy Questions (KCCQ) were examined only at baseline but at 6months for morbidity and mortality.

RESULTS

Seventy-two patients (51 males, 21 females), aged 79.2±9.1years. Thirty-nine patients (54%) had anaemia and 34 had ID (47%). Anaemia was correlated to depression (r=0.37; p=0.001), anxiety (r=0.25; p=0.04), and reduced well-being (r=0.26; p=0.03) in the ESAS; mobility (r=0.33; p=0.005), pain/discomfort (r=0.27; p=0.02), and visual analogue scale of health state (r=-0.28; p=0.02) in the EQ-5D; and physical limitation (r=-0.27; p=0.02), symptom stability; (r=-0.43; p<0.001); (r=-0.25; p=0.033), social limitation;(r=-0.26; p=0.03), overall summary score; (r=-0.24, p=0.046) and clinical summary score; (r=-0.27; p=0.02) in the KCCQ. ID did not correlate to any assessment item. Anaemia was univariably associated with any hospitalization (OR: 3.0; CI: 1.05-8.50, p=0.04), but not to mortality. ID was not significantly associated with any hospitalization or mortality.

CONCLUSION

Anaemia, but not ID, was associated although weakly with symptoms and QoL in patients with advanced HF and palliative home care.