Responder analysis for improvement in 6-min walk test with ferric carboxymaltose in patients with heart failure with reduced ejection fraction and iron deficiency

Identification of three mechanistic pathways for iron-deficient heart failure

Current understanding of iron-deficient heart failure is based on blood tests that are thought to reflect systemic iron stores, but the available evidence suggests greater complexity. The entry and egress of circulating iron is controlled by erythroblasts, which (in severe iron deficiency) will sacrifice erythropoiesis to supply iron to other organs, e.g. the heart. Marked hypoferraemia (typically with anaemia) can drive the depletion of cardiomyocyte iron, impairing contractile performance and explaining why a transferrin saturation < ≈15%-16% predicts the ability of intravenous iron to reduce the risk of major heart failure events in long-term trials (Type 1 iron-deficient heart failure). However, heart failure may be accompanied by intracellular iron depletion within skeletal muscle and cardiomyocytes, which is disproportionate to the findings of systemic iron biomarkers. Inflammation- and deconditioning-mediated skeletal muscle dysfunction-a primary cause of dyspnoea and exercise intolerance in patients with heart failure-is accompanied by intracellular skeletal myocyte iron depletion, which can be exacerbated by even mild hypoferraemia, explaining why symptoms and functional capacity improve following intravenous iron, regardless of baseline haemoglobin or changes in haemoglobin (Type 2 iron-deficient heart failure). Additionally, patients with advanced heart failure show myocardial iron depletion due to both diminished entry into and enhanced egress of iron from the myocardium; the changes in iron proteins in the cardiomyocytes of these patients are opposite to those expected from systemic iron deficiency. Nevertheless, iron supplementation can prevent ventricular remodelling and cardiomyopathy produced by experimental injury in the absence of systemic iron deficiency (Type 3 iron-deficient heart failure). These observations, taken collectively, support the possibility of three different mechanistic pathways for the development of iron-deficient heart failure: one that is driven through systemic iron depletion and impaired erythropoiesis and two that are characterized by disproportionate depletion of intracellular iron in skeletal and cardiac muscle. These mechanisms are not mutually exclusive, and all pathways may be operative at the same time or may occur sequentially in the same patients.

Iron Status and Risk of Heart Disease, Stroke, and Diabetes: A Mendelian Randomization Study in European Adults

BACKGROUND

The relevance of iron status biomarkers for coronary artery disease (CAD), heart failure (HF), ischemic stroke (IS), and type 2 diabetes (T2D) is uncertain. We compared the observational and Mendelian randomization (MR) analyses of iron status biomarkers and hemoglobin with these diseases.

METHODS AND RESULTS

Observational analyses of hemoglobin were compared with genetically predicted hemoglobin with cardiovascular diseases and diabetes in the UK Biobank. Iron biomarkers included transferrin saturation, serum iron, ferritin, and total iron binding capacity. MR analyses assessed associations with CAD (CARDIOGRAMplusC4D [Coronary Artery Disease Genome Wide Replication and Meta-Analysis Plus The Coronary Artery Disease Genetics], n=181 522 cases), HF (HERMES [Heart Failure Molecular Epidemiology for Therapeutic Targets), n=115 150 cases), IS (GIGASTROKE, n=62 100 cases), and T2D (DIAMANTE [Diabetes Meta-Analysis of Trans-Ethnic Association Studies], n=80 154 cases) genome-wide consortia. Observational analyses demonstrated J-shaped associations of hemoglobin with CAD, HF, IS, and T2D. In contrast, MR analyses demonstrated linear positive associations of higher genetically predicted hemoglobin levels with 8% higher risk per 1 SD higher hemoglobin for CAD, 10% to 13% for diabetes, but not with IS or HF in UK Biobank. Bidirectional MR analyses confirmed the causal relevance of iron biomarkers for hemoglobin. Further MR analyses in global consortia demonstrated modest protective effects of iron biomarkers for CAD (7%-14% lower risk for 1 SD higher levels of iron biomarkers), adverse effects for T2D, but no associations with IS or HF.

CONCLUSIONS

Higher levels of iron biomarkers were protective for CAD, had adverse effects on T2D, but had no effects on IS or HF. Randomized trials are now required to assess effects of iron supplements on risk of CAD in high-risk older people.

Baseline characteristics of patients in the randomized study to investigate the efficacy and safety of ferric carboxymaltose as treatment for heart failure with iron deficiency: HEART-FID trial

BACKGROUND

Prior clinical trials have investigated intravenous iron in patients with heart failure (HF) and iron deficiency, but the safety and efficacy of this therapy remains unclear.

METHODS

We report the baseline demographics and clinical characteristics of patients enrolled in the HEART-FID study and compare HEART-FID participants with patients within other contemporary clinical trials of patients with HF with reduced ejection fraction (HFrEF), including other intravenous iron trials.

RESULTS

In the 3,065 participants randomized in HEART-FID, median (IQR) age was 69.7 (62.0-76.5) years, 1,037 (33.8%) were female, 322 (10.5%) were Black, median ejection fraction was 32% (25%-37%), 1,837 (60.0%) had ischemic etiology, and baseline median NT-proBNP was 1,462 (721-2,966) pg/mL. Median baseline hemoglobin was 12.6 (11.6-13.6) g/dL, and median 6-minute walk test distance was 272 (196-350) m, similar to prior intravenous iron HFrEF trials. Common comorbidities included atrial fibrillation/flutter (43.7%), and type 2 diabetes (45.2%). Compared with several recent HFrEF trials, patients enrolled in HEART-FID had similar baseline demographics and clinical characteristics, though a greater proportion of women and Black participants were recruited in HEART-FID. In HEART-FID, HFrEF therapy included a beta-blocker in 92.5%, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker/angiotensin receptor-neprilysin inhibitors (ARNI) in 86.1% (with 29.7% ARNI), and a mineralocorticoid antagonist (MRA) in 55.6%.

CONCLUSIONS

Patients enrolled in HEART-FID were similar to those enrolled in other contemporary HFrEF trials and registries, including trials of intravenous iron in HFrEF. However, the HEART-FID cohort is substantially larger and more racially diverse than prior trials of intravenous iron in HFrEF.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT03037931).

Iron Deficiency in Heart Failure: A Korea-Oriented Review

Iron deficiency (ID) occurs at high frequency across the spectrum of heart failure (HF), with HF severity and race being potentially important predictors for its development. ID, irrespective of anaemia status, leads to poor outcomes in patients with HF, including exacerbated reduction in exercise capacity, poor quality of life (QoL) and increased risk of HF hospitalisation. As ID has a large public health and economic burden in Asia, and patients hospitalised with acute HF in the Asia Pacific vs. other regions commonly present with more severe clinical symptoms, there is a clear need to identify and treat ID promptly in Asian patients with HF. The biomarkers serum ferritin and transferrin saturation are used for ID diagnosis, and periodic screening is recommended in all patients with HF. The intravenous iron treatments, ferric carboxymaltose (FCM) and ferric derisomaltose, have demonstrated efficacy and tolerability in patients with acute or chronic HF and ID, with FCM shown to be cost-effective (and in some cases cost-saving). Meta-analyses support the likely benefits of intravenous FCM for improving QoL and reducing HF hospitalisation, without reducing mortality risk in patients with HF and ID. Accordingly, European Society of Cardiology guidelines recommend considering intravenous FCM for patients with symptomatic HF with left ventricular ejection fraction ≤50% who were recently hospitalised for HF and have ID. Although analyses of Asian patients with HF and ID are limited, the effects of intravenous iron would be expected to be similar to that in White populations; further clarifying studies may be of interest.

Intravenous ferric carboxymaltose for iron repletion following acute heart failure in patients with and without diabetes: a subgroup analysis of the randomized AFFIRM-AHF trial

BACKGROUND

In AFFIRM-AHF, treatment of iron deficiency with intravenous ferric carboxymaltose (FCM) reduced the risk of heart failure (HF) hospitalization and improved quality of life (QoL) vs placebo in patients stabilized following an acute HF (AHF) episode, with no effect on cardiovascular (CV) death. Diabetes and iron deficiency frequently accompany AHF. This post hoc analysis explored the effects of diabetes on outcomes in AFFIRM-AHF patients.

METHODS

Patients were stratified by diabetes yes/no at baseline. The effects of FCM vs placebo on primary (total HF hospitalizations and CV death) and secondary (total CV hospitalizations and CV death; CV death; total HF hospitalizations; time to first HF hospitalization or CV death; and days lost due to HF hospitalizations or CV death) endpoints at Week 52 and change vs baseline in disease-specific QoL (12-item Kansas City Cardiomyopathy Questionnaire [KCCQ-12]) at Week 24 were assessed by subgroup. For each endpoint, the interaction between diabetes status and treatment outcome was explored.

RESULTS

Of 1108 AFFIRM-AHF patients, 475 (FCM: 231; placebo: 244) had diabetes and 633 (FCM: 327; placebo: 306) did not have diabetes. Patients with diabetes were more commonly male (61.5% vs 50.9%), with a higher frequency of ischemic HF etiology (57.9% vs 39.0%), prior HF history (77.7% vs 66.5%), and comorbidities (including previous myocardial infarction [49.3% vs 32.9%] and chronic kidney disease [51.4% vs 32.4%]) than those without diabetes. The annualized event rate/100 patient-years with FCM vs placebo for the primary endpoint was 66.9 vs 80.9 in patients with diabetes (rate ratio [RR]: 0.83, 95% CI 0.58-1.81) and 51.3 vs 66.9 in patients without diabetes (RR: 0.77, 95% CI 0.55-1.07), with no significant interaction between diabetes status and treatment effect (pinteraction = 0.76). Similar findings were observed for secondary outcomes. Change from baseline in KCCQ-12 overall summary score was numerically greater with FCM vs placebo at almost all time points in both subgroups, with no interaction between diabetes and treatment effect at Week 24.

CONCLUSIONS

The clinical and QoL benefits observed with intravenous FCM in patients with iron deficiency following stabilization from an AHF episode are independent of diabetes status. Trial registration Clinicaltrials.gov, NCT02937454 (registered 10.18.2016).