Aims

Iron deficiency is a common finding among patients with heart failure (HF) and is associated with adverse outcomes, including decreased quality of life, increased risk of hospitalization, and decreased survival. Intravenous ferric carboxymaltose (FCM) has been shown to improve outcomes among patients with HF and concomitant iron deficiency, but FCM is associated with an increased risk of hypophosphataemia. We aimed to better characterize this risk among HF populations.

Methods and results

This pooled analysis examined data from 41 studies of adults with iron deficiency across disease states and therapeutic areas. Among the 7931 patients treated with FCM available for analysis, 14% made up the HF subgroup. Additional subgroups included women's health (36%), non-dialysis-dependent chronic kidney disease (NDD-CKD; 27%), haemodialysis-dependent chronic kidney disease (HD-CKD; 1%), gastrointestinal (10%), neurology (3%), and other (10%). The incidence of post-baseline moderate or severe hypophosphataemia (i.e. serum phosphate [PO₄ ^3- ] level <2.0 mg/dL) varied across the therapeutic areas, with the lowest incidences observed in the HD-CKD (0%), HF (8.1%), and NDD-CKD (12.8%) subgroups. The prevalence of moderate or severe hypophosphataemia among the women's health, other, gastrointestinal, and neurology subgroups was 30.1%, 40.6%, 51.0%, and 55.6%, respectively. In the HF subgroup, one patient (<0.1%) had a serum PO₄ ^3- of <1.0 mg/dL recorded, compared with 4.8% and 4.0% of the subjects in the neurology and gastrointestinal groups, respectively. With the exception of the HD-CKD subgroup, mean serum PO₄ ^3- levels decreased through weeks 2 to 4, and then returned toward baseline and plateaued by week 8. The strongest predictor of hypophosphataemia was preserved kidney function (estimated glomerular filtration rate: >60 mL/min/1.73 m² vs. <30 mL/min/1.73 m² ; odds ratio: 12.2). Among patients in the HF subgroup, the incidence of treatment-emergent adverse events potentially related to hypophosphataemia (e.g. cardiac failure, ventricular tachyarrhythmias, fatigue, muscle weakness, bone pain, neurological symptoms, and muscle pain) was lower among FCM-treated patients than among those receiving placebo, and lower among patients with a post-baseline PO₄ ^3- <2 mg/dL vs. those not meeting such criteria.

Conclusions

The risk of laboratory-assessed hypophosphataemia in HF patients treated with FCM was lower than that seen in patients in other therapeutic areas treated with FCM, and clinical events associated with hypophosphataemia are uncommon with FCM therapy in this population. Appropriate monitoring, particularly soon after administration in the unlikely event of repeated dosing in HF patients, will allow for further refinement of management strategies. [Correction added on 24 February 2023, after first online publication: In the preceding sentence, "…administration, will allow…" has been corrected to "…administration in the unlikely event of repeated dosing in HF patients, will allow…" in this version.].

The co-occurrence of cancer and heart failure (HF) represents a significant clinical drawback as each disease interferes with the treatment of the other. In addition to shared risk factors, a growing body of experimental and clinical evidence reveals numerous commonalities in the biology underlying both pathologies. Inflammation emerges as a common hallmark for both diseases as it contributes to the initiation and progression of both HF and cancer. Under stress, malignant and cardiac cells change their metabolic preferences to survive, which makes these metabolic derangements a great basis to develop intersection strategies and therapies to combat both diseases. Furthermore, genetic predisposition and clonal haematopoiesis are common drivers for both conditions and they hold great clinical relevance in the context of personalized medicine. Additionally, altered angiogenesis is a common hallmark for failing hearts and tumours and represents a promising substrate to target in both diseases. Cardiac cells and malignant cells interact with their surrounding environment called stroma. This interaction mediates the progression of the two pathologies and understanding the structure and function of each stromal component may pave the way for innovative therapeutic strategies and improved outcomes in patients. The interdisciplinary collaboration between cardiologists and oncologists is essential to establish unified guidelines. To this aim, pre-clinical models that mimic the human situation, where both pathologies coexist, are needed to understand all the aspects of the bidirectional relationship between cancer and HF. Finally, adequately powered clinical studies, including patients from all ages, and men and women, with proper adjudication of both cancer and cardiovascular endpoints, are essential to accurately study these two pathologies at the same time.

Before the introduction of erythropoiesis-stimulating agents (ESAs) in 1989, repeated transfusions given to patients with end-stage renal disease caused iron overload, and the need for supplemental iron was rare. However, with the widespread introduction of ESAs, it was recognized that supplemental iron was necessary to optimize hemoglobin response and allow reduction of the ESA dose for economic reasons and recent concerns about ESA safety. Iron supplementation was also found to be more efficacious via intravenous compared to oral administration, and the use of intravenous iron has escalated in recent years. The safety of various iron compounds has been of theoretical concern due to their potential to induce iron overload, oxidative stress, hypersensitivity reactions, and a permissive environment for infectious processes. Therefore, an expert group was convened to assess the benefits and risks of parenteral iron, and to provide strategies for its optimal use while mitigating the risk for acute reactions and other adverse effects.