Iron deficiency in heart failure-time to redefine

The Impact of Iron Deficiency on Disease Severity and Myocardial Function in Cardiac Amyloidosis

Background

Reduced cardiac energy is a hallmark feature of heart failure and is common in cardiac amyloidosis (CA) and can be aggravated by the presence of iron deficiency.

Methods

Retrospective analysis of a single tertiary care center CA registry. Prevalence of iron deficiency was determined based on two definitions: (1) Classic definition, ferritin < 100 µg/L irrespective of transferin saturation (TSAT) or ferritin between 100 and 300 µg/L with a TSAT < 20%, and (2) TSAT-based definition, TSAT < 20%.

Results

Out of a total of 393 CA patients who had a full set of iron indices (44% light chain [AL]-CA, 50% transthyretin [ATTR]-CA, remainder other or unspecified CA subtype), 56% had iron deficiency according to the classic definition and 58% according to the TSAT definition, with similar prevalence in AL-CA vs ATTR-CA (p = .135). Per both definitions 58% had anemia. Only the TSAT-based definition was associated with worse functional status (p = .039) and worse cardiac function. CA patients with a TSAT < 20% illustrated features of more pronounced right ventricular (RV) failure including lower TAPSE on echocardiography, lower RV ejection fraction and RV stroke volume index on CMR, increased right-sided filling pressures, lower pulmonary artery pulsatility index, and higher RAP/PCWP ratio by right heart catheterization. Neither the classic nor the TSAT-based definition was associated with a higher risk of all-cause mortality after covariate adjustment.

Conclusion

Iron deficiency is common in cardiac amyloidosis and, when identified with a TSAT < 20%, is associated with worse functional status and more pronounced RV disease, but not with a higher risk of all-cause mortality.

Meta-Analysis and Metaregression of the Treatment Effect of Intravenous Iron in Iron-Deficient Heart Failure

BACKGROUND

Guidelines recommend that intravenous iron should be considered to improve symptoms of heart failure (HF) and reduce the risk for HF admissions in patients after acute HF.

OBJECTIVES

This study sought to analyze the effect of intravenous iron on cardiovascular (CV) death and HF admissions in a broad population of HF patients with iron deficiency and the relation with baseline transferrin saturation (TSAT).

METHODS

A systematic review of all published randomized controlled trials assessing the effect of intravenous iron in patients with iron deficiency and HF between January 1, 2000, and August 26, 2023, was performed. The overall treatment effect was estimated using a fixed effect model for: 1) CV death; 2) CV death and HF admission; 3) first HF admission; and 4) total HF admissions. Metaregression through a mixed effect model was used to explore the impact of baseline TSAT in case of heterogeneity among trial results.

RESULTS

A total of 14 randomized controlled trials were identified in the systematic review and retained in the meta-analysis. Aggregate-level data were included on 6,624 HF patients, 3,407 of whom were randomized to intravenous iron and 3,217 to placebo. Treatment with intravenous iron resulted in a lower risk for CV death (OR: 0.867 [95% CI: 0.755-0.955]; P = 0.0427), combined CV death and HF admission (OR: 0.838 [95% CI: 0.751-0.936]; P = 0.0015), first HF admission (OR: 0.855 [95% CI: 0.744-0.983]; P = 0.0281), and total HF admissions (rate ratio: 0.739 [95% CI: 0.661-0.827]; P < 0.0001). Significant heterogeneity among trial results was observed for first and total HF admissions. Metaregression suggested that some of the heterogeneity was related to the baseline TSAT of the enrolled population, with trials enrolling patients with lower TSAT exhibiting a large effect size on HF-related events.

CONCLUSIONS

The totality of data suggests that treatment with intravenous iron reduces both CV death and HF-related events in a broad population with HF. A lower baseline TSAT might be important for the effect on HF-related events.

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.

Soluble Transferrin Receptor as Iron Deficiency Biomarker: Impact on Exercise Capacity in Heart Failure Patients

The soluble transferrin receptor (sTfR) is a marker of tissue iron status, which could indicate an increased iron demand at the tissue level. The impact of sTfR levels on functional capacity and quality of life (QoL) in non-anemic heart failure (HF) patients with otherwise normal systemic iron status has not been evaluated. We conducted an observational, prospective, cohort study of 1236 patients with chronic HF. We selected patients with normal hemoglobin levels and normal systemic iron status. Tissue iron deficiency (ID) was defined as levels of sTfR > 75th percentile (1.63 mg per L). The primary endpoints were the distance walked in the 6 min walking test (6MWT) and the overall summary score (OSS) of the Minnesota Living with Heart Failure Questionnaire (MLHFQ). The final study cohort consisted of 215 patients. Overall QoL was significantly worse (51 ± 27 vs. 39 ± 20, p-value = 0.006, respectively), and the 6 MWT distance was significantly worse in patients with tissue ID when compared to patients without tissue ID (206 ± 179 m vs. 314 ± 155, p-value < 0.0001, respectively). Higher sTfR levels, indicating increased iron demand, were associated with a shorter distance in the 6 MWT (standardized β = -0.249, p < 0.001) and a higher MLHFQ OSS (standardized β = 0.183, p-value = 0.008). In this study, we show that in patients with normal systemic iron parameters, higher levels of sTfR are strongly associated with an impaired submaximal exercise capacity and with worse QoL.

Iron deficiency in pulmonary vascular disease: pathophysiological and clinical implications

AIMS

Iron deficiency is common in pulmonary hypertension, but its clinical significance and optimal definition remain unclear.

METHODS AND RESULTS

Phenotypic data for 1028 patients enrolled in the Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics study were analyzed. Iron deficiency was defined using the conventional heart failure definition and also based upon optimal cut-points associated with impaired peak oxygen consumption (peakVO2), 6-min walk test distance, and 36-Item Short Form Survey (SF-36) scores. The relationships between iron deficiency and cardiac and pulmonary vascular function and structure and outcomes were assessed. The heart failure definition of iron deficiency endorsed by pulmonary hypertension guidelines did not identify patients with reduced peakVO2, 6-min walk test, and SF-36 (P > 0.208 for all), but defining iron deficiency as transferrin saturation (TSAT) <21% did. Compared to those with TSAT ≥21%, patients with TSAT <21% demonstrated lower peakVO2 [absolute difference: -1.89 (-2.73 to -1.04) mL/kg/min], 6-min walk test distance [absolute difference: -34 (-51 to -17) m], and SF-36 physical component score [absolute difference: -2.5 (-1.3 to -3.8)] after adjusting for age, sex, and hemoglobin (all P < 0.001). Patients with a TSAT <21% had more right ventricular remodeling on cardiac magnetic resonance but similar pulmonary vascular resistance on catheterization. Transferrin saturation <21% was also associated with increased mortality risk (hazard ratio 1.63, 95% confidence interval 1.13-2.34; P = 0.009) after adjusting for sex, age, hemoglobin, and N-terminal pro-B-type natriuretic peptide.

CONCLUSION

The definition of iron deficiency in the 2022 European Society of Cardiology (ESC)/European Respiratory Society (ERS) pulmonary hypertension guidelines does not identify patients with lower exercise capacity or functional status, while a definition of TSAT <21% identifies patients with lower exercise capacity, worse functional status, right heart remodeling, and adverse clinical outcomes.

Iron Deficiency in Heart Failure and Pulmonary Hypertension

Purpose of review

To describe the role of iron deficiency in both heart failure and pulmonary hypertension.

Recent findings

To role of iron deficiency in heart failure is well established and pathophysiologic overlap with pulmonary hypertension exists.

Summary

Iron deficiency is common co-morbidity in heart failure and pulmonary hypertension. The high prevalence is intertwined into the pathophysiology of these conditions (e.g., neurohormonal activation, inflammation). The presence of iron deficiency has a negative impact on cardiomyocytes and cardiac function, skeletal muscle function, and pulmonary vascular function. In heart failure data from over 2000 randomized patients with iron deficiency using a uniform diagnosis, have illustrated beneficial effects on functional status, quality of life, reverse cardiac remodeling, and heart failure admissions. While iron deficiency is recognized to be prevalent in pulmonary hypertension and associated with worse functional status, the absence of a uniform definition and the absence of large prospective randomized controlled trials with iron therapies limits the conclusions on the causal role of iron deficiency such as observed in heart failure.

Prevalence and clinical associations of iron deficiency in patients with decompensated heart failure, depending on the diagnostic criteria used for iron deficiency

Aim. To compare the frequency of iron deficiency (ID) in patients with decompensated heart failure (HF), defined by international guideline criterion ferritin 100 ng/ml or ferritin from 100 to 299 ng/ml with TSAT20% (criterion A) and by bone marrow biopsy criterion TSAT19.8% and serum iron 13 mol/l (criterion B); to evaluate the effect of ID, diagnosed on the basis of different ID criteria, on NT pro-BNP, sST2, CRP levels and New York Heart Association (NYHA) functional classes (FC) distribution between groups with ID and without ID. Materials and methods. The study included 223 patients (median age 73 [65; 82] years, 58% males) who were hospitalized to V.V. Vinogradov Moscow City Clinical Hospital No. 64 with decompensated HF. All patients underwent a standard physiological examination, laboratory and instrumental studies, including determination of NT-proBNP, sST2, CRP, and ferrokinetic parameters (serum iron, transferrin, ferritin). TSAT was calculated as: serum iron / transferrin 3.98. NYHA FC was determined according to Heart Failure Severity Rating Scale score. All patients underwent echocardiography to assess the ejection fraction of the left ventricle. Results. According to criterion A ID was detected in 89% (n=199) of patients. There were no significant differences between levels of CRP, NT-proBNP and sST2. According to criterion B ID was detected in 70% (n=156) of patients. In the ID group, higher levels of CRP (15.1 mg/l vs 6.2 mg/l, p0.001), NT-proBNP (5422 pg/ml vs 2380 pg/ml, p0.001) and sST2 (59.6 ng/ml vs 42 ng/ml, p=0.02) were detected. Intravenous FCM admission according to current international guidelines (diagnosis of ID according to criterion A) is recommended to 57% of patients included in this study. Both methods formed groups with ID, in which patients had higher NYHA FC compared to groups without ID. According to current clinical guidelines, iron deficiency should be assessed according to method 1. More than half of patients (57, n=127) have indications for intravenous FCM to reduce risk of HF hospitalizations. Conclusion. The frequency of ID in patients with decompensated heart failure varies from 70 to 89% depending on the criterion used to diagnose ID, but in any case, remains high. Intravenous FCM should be prescribed in 57% (n=127) of patients. Criterion B, validated against the gold standard of diagnostics, unlike criterion A, makes it possible to form groups of patients with ID and without ID, significantly differing in CRP, NT-proBNP, and sST2 levels.

Neglected Comorbidity of Chronic Heart Failure: Iron Deficiency

Iron deficiency is a significant comorbidity of heart failure (HF), defined as the inability of the myocardium to provide sufficient blood flow. However, iron deficiency remains insufficiently detected. Iron-deficiency anemia, defined as a decrease in hemoglobin caused by iron deficiency, is a late consequence of iron deficiency, and the symptoms of iron deficiency, which are not specific, are often confused with those of HF or comorbidities. HF patients with iron deficiency are often rehospitalized and present reduced survival. The correction of iron deficiency in HF patients is associated with improved functional capacity, quality of life, and rehospitalization rates. Because of the inflammation associated with chronic HF, which complicates the picture of nutritional deficiency, only the parenteral route can bypass the tissue sequestration of iron and the inhibition of intestinal iron absorption. Given the negative impact of iron deficiency on HF progression, the frequency and financial implications of rehospitalizations due to decompensation episodes, and the efficacy of this supplementation, screening for this frequent comorbidity should be part of routine testing in all HF patients. Indeed, recent European guidelines recommend screening for iron deficiency (serum ferritin and transferrin saturation coefficient) in all patients with suspected HF, regular iron parameters assessment in all patients with HF, and intravenous iron supplementation in symptomatic patients with proven deficiency. We thus aim to summarize all currently available data regarding this common and easily improvable comorbidity.

The Effect of Iron Deficiency on Cardiac Function and Structure in Heart Failure with Reduced Ejection Fraction

Over the past decade, the detrimental impact of iron deficiency in heart failure with reduced ejection fraction has become abundantly clear, showing a negative impact on functional status, quality of life, cardiac function and structure, exercise capacity and an increased risk of hospitalisation due to heart failure. Mechanistic studies have shown the impact of iron deficiency in altering mitochondrial function and negatively affecting the already altered cardiac energetics in heart failure with reduced ejection fraction. Such failing energetics form the basis of the alterations to cellular myocyte shortening, culminating in reduced systolic function and cardiac performance. The IRON-CRT trials show that ferric carboxymaltose is capable of improving cardiac structure and cardiac performance. This article discusses the effect of iron deficiency on cardiac function and structure and how it can be alleviated.

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.