Why is Iron Deficiency Recognised as an Important Comorbidity in Heart Failure?

Intravenous iron therapy among patients with heart failure and iron deficiency: An updated meta-analysis of randomized controlled trials

Background

Randomized clinical trials (RCTs) evaluating the role of intravenous (IV) iron administration in patients with heart failure (HF) and iron deficiency (ID) have yielded inconsistent results.

Methods

Electronic search of MEDLINE, EMBASE and OVID databases was performed until November 2022 for RCTs that evaluated the role of IV iron administration in patients with HF and ID. The main study outcomes were the composite of HF hospitalization or cardiovascular mortality, and individual outcome of HF hospitalization. Summary estimates were evaluated using random effects model.

Results

The final analysis included 12 RCTs with 3,492 patients (1,831 patients in the IV iron group and 1,661 patients in the control group). The mean follow-up was 8.3 months. IV iron was associated with a lower incidence in the composite of HF hospitalization or cardiovascular mortality (31.9% vs. 45.3%; relative risk [RR] 0.72; 95% confidence interval [CI] 0.59-0.88) and individual outcome of HF hospitalization (28.4% vs. 42.2; RR 0.69; 95% CI 0.57-0.85). There was no significant difference between both groups in cardiovascular mortality (RR 0.88; 95% CI 0.75-1.04) and all-cause mortality (RR 0.95; 95% CI 0.83-1.09). IV iron was associated with lower New York Heart Association class and higher left ventricular ejection fraction (LVEF). Meta-regression analyses showed no effect modification for the main outcomes based on age, hemoglobin level, ferritin level or LVEF.

Conclusion

Among patients with HF and ID, IV iron administration was associated with reduction in the composite of HF hospitalization or cardiovascular mortality and driven by a reduction in HF hospitalization.

Triad role of hepcidin, ferroportin, and Nrf2 in cardiac iron metabolism: From health to disease

Iron is an essential trace element required for several vital physiological and developmental processes, including erythropoiesis, bone, and neuronal development. Iron metabolism and oxygen homeostasis are interlinked to perform a vital role in the functionality of the heart. The metabolic machinery of the heart utilizes almost 90 % of oxygen through the electron transport chain. To handle this tremendous level of oxygen, the iron metabolism in the heart is utmost crucial. Iron availability to the heart is therefore tightly regulated by (i) the hepcidin/ferroportin axis, which controls dietary iron absorption, storage, and recycling, and (ii) iron regulatory proteins 1 and 2 (IRP1/2) via hypoxia inducible factor 1 (HIF1) pathway. Despite iron being vital to the heart, recent investigations have demonstrated that iron imbalance is a common manifestation in conditions of heart failure (HF), since free iron readily transforms between Fe²⁺ and Fe³⁺via the Fenton reaction, leading to reactive oxygen species (ROS) production and oxidative damage. Therefore, to combat iron-mediated oxidative stress, targeting Nrf2/ARE antioxidant signaling is rational. The involvement of Nrf2 in regulating several genes engaged in heme synthesis, iron storage, and iron export is beginning to be uncovered. Consequently, it is possible that Nrf2/hepcidin/ferroportin might act as an epicenter connecting iron metabolism to redox alterations. However, the mechanism bridging the two remains obscure. In this review, we tried to summarize the contemporary insight of how cardiomyocytes regulate intracellular iron levels and discussed the mechanisms linking cardiac dysfunction with iron imbalance. Further, we emphasized the impact of Nrf2 on the interplay between systemic/cardiac iron control in the context of heart disease, particularly in myocardial ischemia and HF.

Proteome dynasmics and bioinformatics reveal major alterations in the turnover rate of functionally related cardiac and plasma proteins in a dog model of congestive heart failure

Protein pool turnover is a critically important cellular homeostatic component, yet it has been little explored in the context of heart failure (HF) pathophysiology. We employed in vivo ²H labeling/ proteome dynamics for non-biased discovery of turnover alterations involving functionally linked cardiac and plasma proteins in canine tachypacing-induced HF, an established preclinical model of dilated cardiomyopathy. Compared to control, dogs with congestive HF displayed bidirectional turnover changes of 28 cardiac proteins, i.e. reduced half-life of several key enzymes involved in glycolysis, homocysteine metabolism and glycogenesis, and increased half-life of proteins involved in proteolysis. Changes in plasma proteins were more modest: only 5 proteins, involved in various functions including proteolysis inhibition, hemoglobin, calcium and ferric-iron binding, displayed increased or decreased turnover rates. In other dogs undergoing cardiac tachypacing, we infused for 2 weeks the myokine Follistatin-like protein 1 (FSTL1), known for its ameliorative effects on HF-induced alterations. Proteome dynamics proved very sensitive in detecting the partial or complete prevention, by FSTL1, of cardiac and plasma protein turnover alterations. In conclusion, our study unveiled, for the first time in a large mammal, numerous HF-related alterations that may serve as the basis for future mechanistic research and/or as conceptually new molecular markers.

Effect of iron supplementation in patients with heart failure and iron deficiency: A systematic review and meta-analysis

Background

The effectiveness of oral and intravenous iron supplementation in reducing the risk of mortality and hospitalizations in HF patients with iron deficiency is not well-established.

Methods

A thorough literature search was conducted across 2 electronic databases (Medline and Cochrane Central) from inception through March 2021. RCTs assessing the impact of iron supplementation on clinical outcomes in iron deficient HF patients were considered for inclusion. Primary end-points included all-cause mortality and HF hospitalization. Evaluations were reported as odds ratios (ORs) or risk ratios (RRs) with 95% confidence intervals (CI) and analysis was performed using a random effects model. I² index was used to assess heterogeneity.

Results

From the 2599 articles retrieved from initial search, 10 potentially relevant studies (n = 2187 patients) were included in the final analysis. Both oral (OR: 0.93; 95% CI: 0.08-11.30; p = 0.951) and intravenous (OR: 0.97; 95% CI: 0.73-1.29; p = 0.840) iron supplementation did not significantly reduce all-cause mortality. However, intravenous iron supplementation significantly decreased the rates of overall (OR: 0.52; 95% CI: 0.33-0.81; p = 0.004) and HF (OR: 0.42; 95% CI: 0.22-0.80; p = 0.009) hospitalizations. In addition, intravenous ferric carboxymaltose therapy significantly reduced the time to first HF hospitalization or cardiovascular mortality (RR = 0.70; 95% CI = 0.50-1.00; p = 0.048), but had no effect on time to first cardiovascular death (RR: 0.94; 95% CI: 0.70-1.25; p = 0.655).

Conclusion

Oral or intravenous iron supplementation did not reduce mortality in iron deficient HF patients. However, intravenous iron supplementation was associated with a significant decrease in overall and HF hospitalizations.

Iron replacement therapy in heart failure: a literature review

Background

Heart failure (HF) is a major global challenge, emphasised by its designation as the leading cause of hospitalisation in those aged 65 and above. Approximately half of all patients with HF have concurrent iron deficiency (ID) regardless of anaemia status. In HF, iron deficiency is independently associated with higher rates of hospitalisation and death, lower exercise capacity, and poorer quality-of-life than in patients without iron deficiency. With such consequences, several studies have investigated whether correcting ID can improve HF outcomes.

Main body.

As of 1st June 2021, seven randomised controlled trials have explored the use of intravenous (IV) iron in patients with HF and ID, along with various meta-analyses including an individual patient data meta-analysis, all of which are discussed in this review. IV iron was well tolerated, with a comparable frequency of adverse events to placebo. In the context of heart failure with reduced ejection fraction (HFrEF), IV iron reduces the risk of hospitalisation for HF, and improves New York Heart Association (NYHA) functional class, quality-of-life, and exercise capacity (as measured by 6-min walk test (6MWT)) distance and peak oxygen consumption. However, the effect of IV iron on mortality is uncertain. Finally, the evidence for IV iron in patients with acute decompensated heart failure, or heart failure with preserved ejection fraction (HFpEF) is limited.

Conclusions

IV iron improves some outcomes in patients with HFrEF and ID. Patients with HFrEF should be screened for ID, defined as ferritin < 100 µg/L, or ferritin 100–299 µg/L if transferrin saturation < 20%. If ID is found, IV iron should be considered, although causes of ID other than HF must not be overlooked.

The Study of the Aorta Metallomics in the Context of Atherosclerosis

Atherosclerosis is a multifactorial disease, for which the etiology is so complex that we are currently unable to prevent it and effectively lower the statistics on mortality from cardiovascular diseases. Parallel to modern analyses in molecular biology and biochemistry, we want to carry out analyses at the level of micro- and macroelements in order to discover the interdependencies between elements during atherogenesis. In this work, we used the Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) to determine the content of calcium, magnesium, iron, copper, chromium, zinc, manganese, cadmium, lead, and zinc in the aorta sections of people who died a sudden death. We also estimated the content of metalloenzymes MMP-9, NOS-3, and SOD-2 using the immunohistochemical method. It was observed that with the age of the patient, the calcium content of the artery increased, while the content of copper and iron decreased. Very high correlations (correlation coefficient above 0.8) were observed for pairs of parameters in women: Mn–Ca, Fe–Cu, and Ca–Cd, and in men: Mn–Zn. The degree of atherosclerosis negatively correlated with magnesium and with cadmium. Chromium inhibited absorption of essential trace elements such as Cu and Fe due to its content being above the quantification threshold only if Cu and Fe were lower. Moreover, we discussed how to design research for the future in order to learn more about the pathomechanism of atherosclerosis and the effect of taking dietary supplements on the prevalence of cardiovascular diseases.

[Expert consensus regarding treatment of iron deficiency in stable and decompensated patients with heart failure]

In recent years there has been significant interest in treating iron deficiency (ID) in patients with heart failure (HF) due to its high prevalence and detrimental effects in this population. As stated in the 2020 Russain HF guidelines, Intravenous ferric carboxymaltose remains the only proven therapy for ID.This document was prompted by the results from the recent AFFIRM-AHF trial which demonstrates that treatment of ID after acute HF decompensation reduces the risk of future decompensations. Experts have concluded that in HF patients with acute decompensation, a left ventricular ejection fraction of &lt; 50% and ID, Intravenous ferric carboxymaltose reduces future HF hospitalisations. Patients with stable HF may also benefit from treatment of ID to improve quality of life and alleviate symptoms.  It is, therefore, reasonable to screen for and treat ID in patients with HF.

Ferric carboxymaltose for the treatment of iron-deficient heart failure patients: a systematic review and meta-analysis

AIMS

Intravenous ferric carboxymaltose (FCM) has been shown to improve functional capacity and quality of life in iron deficient heart failure patients. However, FCM's effect on hospitalizations and mortality remains unclear as previous randomized controlled trials (RCTs) and their meta-analyses have been underpowered to detect significant differences. We sought to conduct an updated meta-analysis using recently published RCT data.

METHODS AND RESULTS

Online databases were searched from inception until November 2020 for RCTs evaluating the effects of FCM on clinical outcomes in iron-deficient heart failure patients. Outcomes of interest included heart failure hospitalizations, all-cause mortality, and cardiovascular mortality. Meta-analysis was performed using a fixed-effect model and estimates were reported as odds ratios (ORs), hazard ratios, or rate ratios (RRs) along with corresponding 95% confidence intervals (CIs). A total of 1947 patients (n = 1062 in the FCM group; n = 885 in the placebo group) were included. FCM, compared with placebo, significantly reduced the risk of the composite endpoint of time to first heart failure hospitalization or cardiovascular death (hazard ratio = 0.76; 95% CI = 0.63-0.90; I2 = 55%). FCM also significantly reduced the risk of recurrent heart failure hospitalizations (RR = 0.68; 95% CI = 0.54-0.85; I2 = 71%) and recurrent cardiovascular hospitalizations (RR = 0.71; 95% CI = 0.59-0.86; I2 = 56%). However, FCM had no significant effect on the risk of all-cause (OR = 0.97; 95% CI = 0.73-1.28; I2 = 0%) or cardiovascular mortality (OR = 0.93; 95% CI = 0.69-1.27; I2 = 0%).

CONCLUSIONS

Ferric carboxymaltose reduces heart failure hospitalizations and cardiovascular hospitalizations with no beneficial effect on all-cause and cardiovascular mortality in iron-deficient heart failure patients. These findings reinforce the role of FCM as a therapeutic option in heart failure patients.

Iron deficiency and iron therapy in heart failure and chronic kidney disease

PURPOSE OF REVIEW

Iron deficiency is common and associated with adverse outcomes in heart failure, regardless of anemia. Iron deficiency, absolute and functional, with and without anemia, is associated with adverse outcomes in chronic kidney disease (CKD). Heart failure and CKD frequently occur together. Intravenous iron therapy has been shown to reduce heart failure symptoms and improve physical function in heart failure with reduced ejection fraction with iron deficiency. In CKD, intravenous or oral iron therapy are often used for management of anemia, along with erythropoiesis stimulating agents, yet the risks and benefits of intravenous iron use is controversial. In this review, we survey available evidence and ongoing studies of iron deficiency and iron supplementation in heart failure, and integrate with recent evidence on effectiveness and safety of intravenous iron therapy in CKD.

RECENT FINDINGS

Intravenous iron therapy improves heart failure symptoms and physical function in heart failure with reduced ejection fraction and iron deficiency, regardless of anemia, and may reduce heart failure hospitalizations and cardiovascular mortality. Sustained intravenous iron therapy regardless of hemoglobin level in selected patients with end-stage kidney disease receiving hemodialysis improves outcomes, and does not appear to cause infectious complications.

SUMMARY

Iron therapy has important effects in heart failure and CKD, and appears safe in the short term. Ongoing trials will provide additional important information.