Efficacy and safety of iron therapy in patients with chronic heart failure and iron deficiency: a systematic review and meta-analysis based on 15 randomised controlled trials

Intravenous iron for acute and chronic heart failure with reduced ejection fraction (HFrEF) patients with iron deficiency: An updated systematic review and meta-analysis

Patients with heart failure (HF) and iron deficiency are at increased risk of adverse clinical outcomes. We searched databases for randomised controlled trials that compared IV iron to placebo, in patients with HF with reduced ejection fraction (HFrEF). A total of 7,813 participants, all having HFrEF with 3,998 receiving IV iron therapy, and 3,815 control recipients were included. There was a significant improvement in Kansas City Cardiomyopathy Questionnaire favouring IV iron with MD 7.39, 95% CI [3.55, 11.22], p = 0.0002. Subgroup analysis, based on acute and chronic HF, has displayed a sustained statistical significance. Additionally, a significant increase in the left ventricular ejection fraction % was observed, with MD 3.76, 95% CI [2.32, 5.21], p < 0.00001. A significant improvement in 6-min walk test was noted, with MD 34.87, 95% CI [20.02, 49.72], p < 0.00001. Furthermore, IV iron showed significant improvement in NYHA class, peak VO2, serum ferritin, and haemoglobin levels. Finally, despite the lack of difference in terms of all-cause hospitalisation and HF-related death, IV iron was associated with a significant reduction in HF-related, any cardiovascular reason hospitalisations, and all-cause death; which supports the need for implementation of IV iron as a standard of care in patients with HF and iron deficiency.

Intravenous Iron for Heart Failure: Updated Systematic Review and Meta-Analysis

While the administration of intravenous (IV) iron to those with heart failure has been implicated to be associated with a possible reduction in hospitalizations and improvement in symptoms, a recent large multicenter trial only showed modest benefits in reducing hospitalization, necessitating the updated systematic review. We conducted a systematic review and meta-analysis, searching the MEDLINE and EMBASE database until January 9, 2023. Outcomes included total heart failure hospitalizations, first heart failure hospitalization, six-minute walk test (6MWT) distance, and incidence of infection. There were 13 studies with 3410 participants (1,790 with IV iron). Pooled analysis that reported the incidence of cardiovascular death showed that patients with IV iron did not have significantly lower odds of cardiovascular death or first heart failure hospitalization. In contrast, those who received IV iron had significantly lower total heart failure hospitalization (pooled odds ratio (OR) 0.63, 95% confidence interval (CI) 0.44-0.90, I2 59.0%, P = .017) and a composite of cardiovascular death and first heart failure hospitalization (pooled OR 0.55, 95% CI 0.47-0.64, I2 0%, P = .656). While the efficacy is modest, IV iron therapy could be associated with reduced hospitalization for heart failure without significant adverse events.

Treating Iron Deficiency (ID) Anemia in Heart Failure (HF) Patients with IV Iron: A Meta-Analysis

Findings on the effects of iron on heart failure (HF) hospitalizations and mortality among patients with iron deficiency (ID) and HF remain conflicting across different studies. We performed a meta-analysis of clinical trials assessing the clinical, hematic and cardiovascular benefits of treating ID in HF patients. We completed a systematic search for studies comparing IV iron to placebo in HF patients with ID. The primary outcomes were rates of HF hospitalization and all-cause mortality. Secondary outcomes included change in hematic values, New York Heart Association (NYHA) class and ejection fraction. We applied a random-effects model with planned sensitivity analyses of studies with skewed effect sizes. Nine studies were included with a total of 2,261 patients. Analysis revealed that treatment of HF patients with IV iron replacement significantly reduced the odds of HF hospitalization (odds ratio (OR): 0.44; 95% confidence interval (CI): 0.24 to 0.78; p=0.005, I2=67%),) but did not significantly impact all-cause mortality compared to placebo (OR: 0.89; 95%, CI: 0.67 to 1.19; p=0.44, I2: 0%). Analysis showed that IV iron treatment group had significantly higher serum ferritin, transferrin saturation and hemoglobin (Hb) levels. They also had lower NYHA class -1.90 (95% CI (-2.91 to -0.89); p<0.001, I2:89%) with higher ejection fraction 0.50 (95% CI (0.09 to 0.90) p=0.016, I2:86%). Treatment with IV iron in HF patients with ID is associated with a significant reduction of HF hospitalization but no effects on all-cause mortality. There were also significant increases in hematic values and ejection fraction with a reduction in NYHA class.

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.

Iron-Deficiency in Atopic Diseases: Innate Immune Priming by Allergens and Siderophores

Although iron is one of the most abundant elements on earth, about a third of the world's population are affected by iron deficiency. Main drivers of iron deficiency are beside the chronic lack of dietary iron, a hampered uptake machinery as a result of immune activation. Macrophages are the principal cells distributing iron in the human body with their iron restriction skewing these cells to a more pro-inflammatory state. Consequently, iron deficiency has a pronounced impact on immune cells, favoring Th2-cell survival, immunoglobulin class switching and primes mast cells for degranulation. Iron deficiency during pregnancy increases the risk of atopic diseases in children, while both children and adults with allergy are more likely to have anemia. In contrast, an improved iron status seems to protect against allergy development. Here, the most important interconnections between iron metabolism and allergies, the effect of iron deprivation on distinct immune cell types, as well as the pathophysiology in atopic diseases are summarized. Although the main focus will be humans, we also compare them with innate defense and iron sequestration strategies of microbes, given, particularly, attention to catechol-siderophores. Similarly, the defense and nutritional strategies in plants with their inducible systemic acquired resistance by salicylic acid, which further leads to synthesis of flavonoids as well as pathogenesis-related proteins, will be elaborated as both are very important for understanding the etiology of allergic diseases. Many allergens, such as lipocalins and the pathogenesis-related proteins, are able to bind iron and either deprive or supply iron to immune cells. Thus, a locally induced iron deficiency will result in immune activation and allergic sensitization. However, the same proteins such as the whey protein beta-lactoglobulin can also transport this precious micronutrient to the host immune cells (holoBLG) and hinder their activation, promoting tolerance and protecting against allergy. Since 2019, several clinical trials have also been conducted in allergic subjects using holoBLG as a food for special medical purposes, leading to a reduction in the allergic symptom burden. Supplementation with nutrient-carrying lipocalin proteins can circumvent the mucosal block and nourish selectively immune cells, therefore representing a new dietary and causative approach to compensate for functional iron deficiency in allergy sufferers.