Cardiovascular outcomes of intravenous iron in perspective of clinical trials and the use of different iron preparations

Clinical and Molecular Aspects of Iron Metabolism in Failing Myocytes

Heart failure (HF) is a common disease that causes significant limitations on the organism's capacity and, in extreme cases, leads to death. Clinically, iron deficiency (ID) plays an essential role in heart failure by deteriorating the patient's condition and is a prognostic marker indicating poor clinical outcomes. Therefore, in HF patients, supplementation of iron is recommended. However, iron treatment may cause adverse effects by increasing iron-related apoptosis and the production of oxygen radicals, which may cause additional heart damage. Furthermore, many knowledge gaps exist regarding the complex interplay between iron deficiency and heart failure. Here, we describe the current, comprehensive knowledge about the role of the proteins involved in iron metabolism. We will focus on the molecular and clinical aspects of iron deficiency in HF. We believe that summarizing the new advances in the translational and clinical research regarding iron deficiency in heart failure should broaden clinicians' awareness of this comorbidity.

A Systematic Review, Meta-Analysis, and Indirect Comparison of Blindly Adjudicated Cardiovascular Event Incidence with Ferric Derisomaltose, Ferric Carboxymaltose, and Iron Sucrose

INTRODUCTION

Intravenous (IV) iron is the preferred treatment for patients with iron deficiency anemia (IDA) who require rapid replenishment of iron stores or in whom oral iron is not tolerated or effective. Data from two large-scale randomized controlled trials (RCTs) have recently been published reporting the incidence of adjudicated cardiovascular events after ferric derisomaltose (FDI) and iron sucrose (IS). The objective was to calculate the relative incidence of cardiovascular events with FDI and IS, and to conduct an indirect comparison with ferric carboxymaltose (FCM) based on previously published studies of cardiovascular risk.

METHODS

RCTs reporting the incidence of blindly adjudicated cardiovascular events in IDA patients treated with IV iron were identified by systematic literature review (SLR). Pairwise random effects meta-analyses of FDI versus IS, and FCM versus IS were conducted for the pre-specified adjudicated composite cardiovascular endpoint of: death due to any cause, nonfatal myocardial infarction, nonfatal stroke, unstable angina requiring hospitalization, congestive heart failure, arrhythmia, and protocol-defined hypertensive and hypotensive events. Analyses were also conducted for the composite endpoint excluding blood pressure events. Meta-analysis results were combined in an adjusted indirect comparison to provide an indirect estimate of cardiovascular risk with FDI versus FCM.

RESULTS

The SLR retrieved 694 unique articles, of which four were RCTs reporting the incidence of the composite cardiovascular endpoint; two studies comparing FCM (N = 1529) with IS (N = 1505), and two studies comparing FDI (N = 2008) with IS (N = 1000). The odds ratios of the composite CV endpoint were 0.59 (95% confidence interval: 0.39-0.90) for FDI versus IS, 1.12 (95% CI 0.90-1.40) for FCM versus IS, and the indirect OR for FDI versus FCM was 0.53 (95% CI 0.33-0.85).

CONCLUSIONS

Pooling data from four large-scale RCTs suggested that FDI was associated with significantly lower incidence of cardiovascular adverse events compared to both FCM and IS.

Factors influencing safety and efficacy of intravenous iron-carbohydrate nanomedicines: From production to clinical practice

Iron deficiency is an important subclinical disease affecting over one billion people worldwide. A growing body of clinical records supports the use of intravenous iron-carbohydrate complexes for patients where iron replenishment is necessary and oral iron supplements are either ineffective or cannot be tolerated by the gastrointestinal tract. A critical characteristic of iron-carbohydrate drugs is the complexity of their core-shell structure, which has led to differences in the efficacy and safety of various iron formulations. This review describes parameters influencing the safety and effectiveness of iron-carbohydrate complexes during production, storage, handling, and clinical application. We summarized the physicochemical and biological assessments of commercially available iron carbohydrate nanomedicines to provide an overview of publicly available data. Further, we reviewed studies that described how subtle differences in the manufacturing process of iron-carbohydrate complexes can impact on the physicochemical, biological, and clinical outcomes of original product versus their intended copies or so-called iron "similar" products.

Safety concerns about intravenous iron therapy in patients with chronic kidney disease

Anaemia in chronic kidney disease (CKD) is managed primarily with erythropoiesis-stimulating agents (ESAs) and iron therapy. Following concerns around ESA therapy, intravenous (IV) iron is being administered more and more worldwide. However, it is still unclear whether this approach is safe at very high doses or in the presence of very high ferritin levels. Some observational studies have shown a relationship between either high ferritin level or high iron dose and increased risk of death, cardiovascular events, hospitalization or infection. Others have not been able to confirm these findings. However, they suffer from indication biases. On the other hand, the majority of randomized clinical trials have only a very short follow-up (and thus drug exposure) and are inadequate to assess the mortality risk. None of them have tested the role of different iron doses on hard end points. With the lack of clear evidence coming from well-designed and large-scale studies, several data suggest that excessive iron therapy may be toxic in several aspects, ranging from iron overload to tissue damage from labile iron. A number of experimental and clinical data suggest that either excessive iron therapy or iron overload may be a possible culprit of atherogenesis. The process seems to be mediated by oxidative stress. Iron therapy should also be used cautiously in the presence of active infections, since iron is essential for bacterial growth. Recently, the European Medicines Agency officially raised concerns about rare hypersensitivity reactions following IV iron administration. The balance has been in favour of benefits. In several European countries, this has created a lot of confusion and somewhat slowed the run towards excessive use. Altogether, IV iron remains a mainstay of anaemia treatment in CKD patients. However, in our opinion, its excessive use should be avoided, especially in patients with high ferritin levels and when ESA agents are not contraindicated.

Iron therapy in chronic kidney disease: Recent changes, benefits and risks

Anemia is a common complication in patients with chronic kidney disease (CKD), mainly due to inadequate renal production of erythropoietin. In hemodialysis (HD) patients this condition may be aggravated by iron deficiency (absolute or functional). The correction of this anemia is usually achieved by treatment with erythropoiesis stimulating agents (ESAs) and iron (oral or intravenous). Studies questioning the safety of ESAs (especially at higher doses) changed the pattern of anemia treatment in CKD patients. According to the new guidelines, when transferrin saturation is lower than 30% and ferritin lower than 500 ng/mL, a trial with iron should be started, to avoid therapy with ESAs or at least to reduce the doses needed to treat the anemia. Recent reports showed increasing ferritin levels, towards values above 800 ng/mL, in CKD patients treated according to the guidelines. In this review we focus on the risks of the increased iron use to treat CKD anemia, namely, iron overload and toxicity, increased risk of infections, as well as mortality.