Should we use ferritin in the diagnostic criteria of iron deficiency in heart failure patients?

Iron metabolism biomarkers and mortality risk in U.S. patients with congestive heart failure: NHANES 1999-2018 analysis

BACKGROUND AND AIMS

Iron deficiency is a major public health concern. We aimed to assess the predictive capability of 4 iron metabolism biomarkers for all-cause and cardiovascular disease-specific mortality in U.S. patients with congestive heart failure (CHF).

METHODS AND RESULTS

1904 CHF patients aged ≥20 years were enrolled from NHANES, 1999-2000 to 2017-2018. All analyses were weighted to provide nationally representative estimates. Among 1905 CHF patients, mean age was 71 years, and 1024 (53.8%), 459 (24.1%), 206 (10.8%), and 216 (11.3%) were Non-Hispanic Black, Non-Hispanic White, Hispanic-Mexican American, and Hispanic-Other Hispanic, respectively. During follow-ups, 1080 deaths occurred. Median follow-up time was 5.08 years. Per-unit increase in natural-logarithmic-transformed iron and transferrin saturation decreased all-cause mortality risk separately by 33.0% (adjusted hazard ratio: 0.670, 95% confidence interval: 0.563 to 0.797, P < 0.001) and 32.6% (0.674, 0.495 to 0.917, 0.013), and per-unit increase in transferrin receptor increased mortality risk by 33.7% (1.337, 1.104 to 1.618, 0.004). Two derivates from 3 significant iron biomarkers were generated - transferrin receptor to natural-logarithmic-transformed iron ratio (TRI) and transferrin receptor to natural-logarithmic-transformed transferrin saturation ratio (TRTS), which were significantly associated with all-cause mortality, with per-unit increase corresponding to 2.692- and 1.655-fold increased all-cause mortality risk (P: 0.003 and 0.023). Only iron and TRTS were associated with the significant risk of cardiovascular disease-specific mortality (P: 0.004 and 0.017).

CONCLUSIONS

Our findings identified 3 iron metabolism biomarkers that were individually, significantly, and independently associated with all-cause mortality in patients with CHF, and importantly 2 derivates generated exhibited stronger predictive capability.

Iron deficiency and anemia in pediatric dilated cardiomyopathy are associated with clinical, biochemical, and hematological markers of severe disease and adverse outcomes

BACKGROUND

There is limited evidence regarding the prevalence and impact of iron deficiency (ID) in children with dilated cardiomyopathy (DCM).

METHODS

Retrospective single-center review of all children between 2010 and 2020 with a diagnosis of DCM and complete iron studies. ID was defined as ≥2 of ferritin <20 μg/liter, iron <9 μmol/liter, transferrin >3 g/liter, or transferrin saturation (TSat) <15%. Clinical and laboratory indices and freedom from a composite adverse event (CAE) of mechanical circulatory support (MCS), heart transplant, or death were compared between children with and without ID.

RESULTS

Of 138 patients with DCM, 47 had available iron studies. Twenty-nine (62%) were iron deficient. Children with ID were more likely to be receiving inotropes (17, 59%, p = 0.005) or invasive/noninvasive ventilation (13, 45%, p = 0.016) than those who were iron replete. They had a higher incidence of anemia (22, 76%, p = 0.004) and higher NT-proBNP (1,590 pmol/liter, IQR 456-3,447, p = 0.001). Children with ID had significantly less freedom from the CAE at 1-year (54% ± 10%), 2-years (45 ± 10), and 5-years (37% ± 11%) than those without (p = 0.011). ID and anemia were the only significant predictors of the CAE on univariate Cox regression.

CONCLUSIONS

ID is highly prevalent in children with DCM. Iron studies are undermeasured in clinical practice, but ID is associated with severe heart failure (HF) and an increased risk of the CAE. The need for iron replacement therapy should be considered in children who present in HF with DCM.

Iron Deficiency in Chronic Pediatric Heart Failure: Overall Assessment and Outcomes in Dilated Cardiomyopathy

OBJECTIVE

To evaluate the frequency of iron status assessment in pediatric heart failure and the prevalence and adverse effects of absolute iron deficiency in dilated cardiomyopathy-induced heart failure.

STUDY DESIGN

We retrospectively reviewed records of children with chronic heart failure at our center between 2010 and 2020. In children with dilated cardiomyopathy, we analyzed baseline cardiac function, hemoglobin level, and subsequent risk of composite adverse events (CAE), including death, heart transplant, ventricular assist device (VAD) placement, and transplant registry listing. Absolute iron deficiency and iron sufficiency were defined as transferrin saturations <20% and ≥30%, respectively; and indeterminant iron status as 20%-29%.

RESULTS

Of 799 patients with chronic heart failure, 471 (59%) had no iron-related laboratory measurements. Of 68 children with dilated cardiomyopathy, baseline transferrin saturation, and quantitative left ventricular ejection fraction (LVEF), 33 (49%) and 14 (21%) were iron deficient and sufficient, respectively, and 21 (31%) indeterminant. LVEF was reduced to 23.6 ± 12.1% from 32.9 ± 16.8% in iron deficiency and sufficiency, respectively (P = .04), without a significant difference in hemoglobin. After stratification by New York Heart Association classification, in advanced class IV, hemoglobin was reduced to 10.9 ± 1.3 g/dL vs 12.7 ± 2.0 g/dL in iron deficiency and sufficiency, respectively (P = .01), without a significant difference in LVEF.

CONCLUSIONS

In this single-center study, iron deficiency was not monitored in most children with chronic heart failure. In pediatric dilated cardiomyopathy-induced heart failure, absolute iron deficiency was prevalent and associated with clinically consequential and possibly correctable decreases in cardiac function and hemoglobin concentration.

How I treat anemia with red blood cell transfusion and iron

Severe anemia is commonly treated with red blood cell transfusion. Clinical trials have demonstrated that a restrictive transfusion strategy of 7 to 8 g/dL is as safe as a liberal transfusion strategy of 9 to 10 g/dL in many clinical settings. Evidence is lacking for subgroups of patients, including those with preexisting coronary artery disease, acute myocardial infarction, congestive heart failure, and myelodysplastic neoplasms. We present 3 clinical vignettes that highlight the clinical challenges in caring for patients with coronary artery disease with gastrointestinal bleeding, congestive heart failure, or myelodysplastic neoplasms. We emphasize that transfusion practice should be guided by patient symptoms and preferences in conjunction with the patient's hemoglobin concentration. Along with the transfusion decision, evaluation and management of the etiology of the anemia is essential. Iron-restricted erythropoiesis is a common cause of anemia severe enough to be considered for red blood cell transfusion but diagnosis and management of absolute iron deficiency anemia, the anemia of inflammation with functional iron deficiency, or their combination may be problematic. Intravenous iron therapy is generally the treatment of choice for absolute iron deficiency in patients with complex medical disorders, with or without coexisting functional iron deficiency.

Markers of Iron Metabolism and Outcomes in Patients with Heart Failure: A Systematic Review

Iron deficiency (ID) in conjunction with heart failure (HF) poses a challenge for clinicians and is associated with worse HF outcomes. Treatment of ID with IV iron supplementation for patients with HF has demonstrated benefits in quality of life (QoL) and HF-related hospitalizations. The aim of this systematic review was to summarize the evidence linking iron metabolism biomarkers with outcomes in patients with HF to assist in the optimal use of these biomarkers for patient selection. A systematic review of observational studies in English from 2010 to 2022 was conducted using PubMed, with keywords of “Heart Failure” and respective iron metabolism biomarkers (“Ferritin”, “Hepcidin”, “TSAT”, “Serum Iron”, and “Soluble Transferrin Receptor”). Studies pertaining to HF patients, with available quantitative data on serum iron metabolism biomarkers, and report of specific outcomes (mortality, hospitalization rates, functional capacity, QoL, and cardiovascular events) were included, irrespective of left ventricular ejection fraction (LVEF) or other HF characteristics. Clinical trials of iron supplementation and anemia treatment were removed. This systematic review was conducive to formal assessment of risk of bias via Newcastle-Ottawa Scale. Results were synthesized based on their respective adverse outcomes and iron metabolism biomarker(s). Initial and updated searches identified 508 unique titles once duplicates were removed. The final analysis included 26 studies: 58% focused on reduced LVEF; age range was 53–79 years; males composed 41–100% of the reported population. Statistically significant associations of ID were observed with all-cause mortality, HF hospitalization rates, functional capacity, and QoL. Increased risk for cerebrovascular events and acute renal injury have also been reported, but these findings were not consistent. Varying definitions of ID were utilized among the studies; however, most studies employed the current European Society of Cardiology criteria: serum ferritin < 100 ng/mL or the combination of ferritin between 100–299 ng/mL and transferrin saturation (TSAT) < 20%. Despite several iron metabolism biomarkers demonstrating strong association with several outcomes, TSAT better predicted all-cause mortality, as well as long-term risk for HF hospitalizations. Low ferritin was associated with short-term risk for HF hospitalizations, worsening functional capacity, poor QoL, and development of acute renal injury in acute HF. Elevated soluble transferrin receptor (sTfR) levels were associated with worse functional capacity and QoL. Finally, low serum iron was significantly associated with increased risk for cardiovascular events. Considering the lack of consistency among the iron metabolism biomarkers for association with adverse outcomes, it is important to incorporate additional biomarker data, beyond ferritin and TSAT, when assessing for ID in HF patients. These inconsistent associations question how best to define ID to ensure proper treatment. Further research, potentially tailored to specific HF phenotypes, is required to optimize patient selection for iron supplementation therapy and appropriate targets for iron stores replenishment.

Iron Deficiency in Heart Failure: Mechanisms and Pathophysiology

Iron is an essential micronutrient for a myriad of physiological processes in the body beyond erythropoiesis. Iron deficiency (ID) is a common comorbidity in patients with heart failure (HF), with a prevalence reaching up to 59% even in non-anaemic patients. ID impairs exercise capacity, reduces the quality of life, increases hospitalisation rate and mortality risk regardless of anaemia. Intravenously correcting ID has emerged as a promising treatment in HF as it has been shown to alleviate symptoms, improve quality of life and exercise capacity and reduce hospitalisations. However, the pathophysiology of ID in HF remains poorly characterised. Recognition of ID in HF triggered more research with the aim to explain how correcting ID improves HF status as well as the underlying causes of ID in the first place. In the past few years, significant progress has been made in understanding iron homeostasis by characterising the role of the iron-regulating hormone hepcidin, the effects of ID on skeletal and cardiac myocytes, kidneys and the immune system. In this review, we summarise the current knowledge and recent advances in the pathophysiology of ID in heart failure, the deleterious systemic and cellular consequences of ID.

Iron deficiency and short-term adverse events in patients with decompensated heart failure

BACKGROUND

For patients with heart failure (HF), iron deficiency (ID) is a common therapeutic target. However, little is known about the utility of transferrin saturation (TSAT) or serum ferritin for risk stratification in decompensated HF (DHF) or the European Society of Cardiology's (ESC) current definition of ID (ferritin < 100 μg/L or TSAT < 20% if ferritin is 100-299 μg/L). We evaluated the association between these potential markers of ID and the risk of 30-day readmission for HF or death in patients with DHF.

METHODS

We retrospectively included 1701 patients from a multicenter registry of DHF. Serum ferritin and TSAT were evaluated 24-72 h after hospital admission, and multivariable Cox regression was used to assess their association with the composite endpoint.

RESULTS

Participants' median (quartiles) age was 76 (68-82) years, 43.8% were women, and 51.7% had a left ventricular ejection fraction > 50%. Medians for NT-proBNP, TSAT, and ferritin were 4067 pg/mL (1900-8764), 14.1% (9.0-20.3), and 103 ug/L (54-202), respectively. According to the current ESC definition, 1,246 (73.3%) patients had ID. By day 30, there were 177 (10.4%) events (95 deaths and 85 HF readmission). After multivariable adjustment, lower TSAT was associated with outcome (p = 0.009) but serum ferritin was not (HR 1.00; 95% confidence interval 0.99-1.00, p = 0.347).

CONCLUSIONS

Lower TSAT, but not ferritin, was associated with a higher risk of short-term events in patients with DHF. Further research is needed to confirm these findings and the utility of serum ferritin as a marker of ID in DHF.