Fibroblast Growth Factor 23 and Long-Term Cardiac Function: The Multi-Ethnic Study of Atherosclerosis

Fibroblast growth factor 23 during septic shock and myocardial injury in ICU patients

Objective

Fibroblast growth factor 23 (FGF23) has been recognized as an important biomarker of cardiovascular disease and is closely related to inflammation over the past decade. This study aimed to assess the relationship between FGF23 and myocardial injury in patients with sepsis.

Methods

We sequentially measured serum FGF23, Klotho, biomarkers of inflammation (CRP, IL-6 and WBC), myocardial injury (cTnI and N-terminal B-type natriuretic peptide) and sepsis (procalcitonin) at peak of intercurrent septic shock and after complete resolution or before death in a series of 29 patients with septic shock. 29 healthy adults without infections were used as controls.

Results

There was a difference in serum FGF23 level between patients with septic shock and healthy adults (p < 0.0001), and the peak level of FGF23 in septic shock in the survivor group was higher than that after complete remission (p < 0.0001). No statistical difference was found in the level of FGF23 before and after treatment in the death group (p = 0.0947). At the peak of septic shock, FGF23 was significantly correlated with inflammatory markers, CRP (r = 0.8063, p < 0.0001), PCT (r = 0.6091, p = 0.0005) and WBC (r = 0.8312, p < 0.0001), while the correlation with IL-6 was not statistically significant (r = 0.0098, p = 0.9598). At the same time, it was found that FGF23 was significantly correlated with myocardial injury markers, cTNI (r = 0.8475, p < 0.0001) and NTproBNP (r = 0.8505, p < 0.0001). Nevertheless, FGF23 and klotho are not correlated (r = 0.2609, p = 0.1717).

Conclusion

In conclusion, in patients with septic shock and myocardial injury, the exacerbation of inflammation in the septic process was accompanied by a abnormal increase of circulating FGF23 level. FGF23 also subsided after the improvement of inflammation, and the opposite was true for patients who did not survive. The up-regulation of FGF23 may be involved in the response of patients to septic shocks, and it is also speculated that FGF23 is involved in the myocardial injury of septic shock.

Associations of Circulating Vascular Cell Adhesion Molecule-1 and Intercellular Adhesion Molecule-1 With Long-Term Cardiac Function

BACKGROUND

Although VCAM-1 (vascular cell adhesion molecule-1) and ICAM-1 (intercellular adhesion molecule-1) have been associated with incident heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF), the associations of VCAM-1 and ICAM-1 with sensitive measures of cardiac structure/function are unclear. The objective of this study is to evaluate associations between VCAM-1, ICAM-1, and measures of cardiac structure and function as potential pathways through which cellular adhesion molecules promote HFpEF and AF risk.

METHODS AND RESULTS

In MESA (Multi-Ethnic Study of Atherosclerosis), we evaluated the associations of circulating VCAM-1 and ICAM-1 at examination 2 (2002-2004) with measures of cardiac structure/function on cardiac magnetic resonance imaging at examination 5 (2010-2011) after multivariable adjustment. Mediation analysis of left atrial (LA) strain on the association between VCAM-1 or ICAM-1 and AF or HFpEF was also performed. Overall, 2304 individuals (63±10 years; 47% men) with VCAM-1 or ICAM-1, cardiac magnetic resonance imaging, and covariate data were included in analysis. Higher VCAM-1 and ICAM-1 were associated with lower LA peak longitudinal strain and worse global circumferential left ventricular strain but were not associated with left ventricular myocardial scar or interstitial fibrosis. Lower LA peak longitudinal strain mediated 8% (95% CI, 2-30) of the relationship between VCAM-1 and HFpEF and 9% (95% CI, 2-21) of the relationship between VCAM-1 and AF.

CONCLUSIONS

Higher VCAM-1 and ICAM-1 were associated with lower LA function and left ventricular systolic function but were not associated with myocardial scar or interstitial fibrosis. VCAM-1 and ICAM-1 may promote HFpEF and AF risk through impaired LA reservoir function.

FGF23 and klotho at the intersection of kidney and cardiovascular disease

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). As CKD progresses, CKD-specific risk factors, such as disordered mineral homeostasis, amplify traditional cardiovascular risk factors. Fibroblast growth factor 23 (FGF23) regulates mineral homeostasis by activating complexes of FGF receptors and transmembrane klotho co-receptors. A soluble form of klotho also acts as a 'portable' FGF23 co-receptor in tissues that do not express klotho. In progressive CKD, rising circulating FGF23 levels in combination with decreasing kidney expression of klotho results in klotho-independent effects of FGF23 on the heart that promote left ventricular hypertrophy, heart failure, atrial fibrillation and death. Emerging data suggest that soluble klotho might mitigate some of these effects via several candidate mechanisms. More research is needed to investigate FGF23 excess and klotho deficiency in specific cardiovascular complications of CKD, but the pathophysiological primacy of FGF23 excess versus klotho deficiency might never be precisely resolved, given the entangled feedback loops that they share. Therefore, randomized trials should prioritize clinical practicality over scientific certainty by targeting disordered mineral homeostasis holistically in an effort to improve cardiovascular outcomes in patients with CKD.

Effect of etelcalcetide versus alfacalcidol on left ventricular function and feature-tracking cardiac magnetic resonance imaging in hemodialysis-a post-hoc analysis of a randomized, controlled trial

BACKGROUND

Calcimimetic therapy with etelcalcetide (ETEL) has been shown to attenuate the advancement of left ventricular (LV) hypertrophy in hemodialysis patients measured by cardiac magnetic resonance (CMR). The aim of the study was to evaluate whether this effect is accompanied by alterations in LV function and myocardial composition.

METHODS

This was a post-hoc analysis of a randomized-controlled trial of ETEL versus Alfacalcidol (ALFA) in 62 hemodialysis patients. LV function was assessed using LV ejection fraction (LVEF) and LV global longitudinal strain (GLS) on feature-tracking (FT) CMR. Myocardial tissue characteristics were analyzed using parametric T1 and T2 mapping.

RESULTS

Of the total study cohort (n = 62), 48 subjects completed both CMR scans with sufficient quality for FT analysis. In the one-year follow-up, LV GLS deteriorated in the ALFA group, whereas the ETEL group remained stable (LV GLS change: + 2.6 ± 4.6 versus + 0.3 ± 3.8; p = 0.045 when adjusting for randomization factors and baseline LV GLS). We did not observe a difference in the change of LVEF between the two groups (p = 0.513). The impact of ETEL treatment on LV GLS over time remained significant after additional adjustment for the change in LV mass during the study period. ETEL treatment did not significantly affect other CMR parameters. There were no changes in myocardial composition between treatment groups (T1 time change: + 15 ± 42 versus + 10 ± 50; p = 0.411; T2 time change: - 0.13 ± 2.45 versus - 0.70 ± 2.43; p = 0.652).

CONCLUSIONS

In patients undergoing hemodialysis, treatment with ETEL was protective against deterioration of LV longitudinal function, as evaluated through FT CMR, when compared to the control therapy of ALFA. This effect was not mediated by the change in LV mass. Trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03182699 . Unique identifier: NCT03182699.

Increased Serum Fibroblast Growth Factor 23 Predicts Mortality in People With HIV/HCV Coinfection

BACKGROUND

People with HIV and hepatitis C virus (HCV) coinfection experience excess mortality because of multiple causes. Identification of biomarkers associated with mortality beyond that attributable to liver fibrosis may be relevant for prognostication. Fibroblast growth factor 23 (FGF23), a phosphotropic hormone, predicts adverse outcomes in several chronic conditions. We aimed to investigate whether elevated FGF23 predicts all-cause mortality in patients with HIV/HCV coinfection.

METHODS

We included patients with HIV/HCV coinfection from the Canadian Coinfection Cohort with available serum FGF23, fibrosis biomarker fibrosis-4 (FIB-4), and at least 1-year follow-up. Elevated FGF23 and advanced liver fibrosis were defined as FGF23 > 241 reference unit/mL and FIB-4 > 3.25, respectively. All-cause mortality was analyzed using survival analysis. The effect of advanced liver fibrosis as a mediator on mortality was estimated by mediation analysis.

RESULTS

Three hundred twenty-one patients were included (24% with elevated FGF23, 19% with advanced liver fibrosis). During a mean follow-up period of 8.4 years, 34% of the cohort died. The incidence rate of all-cause mortality was higher in patients with elevated FGF23 (66.1 per 1000 person-years, 95% confidence interval 45.8 to 92.3) relative to patients without elevated FGF23 (37.5 per 1000 person-years, 95% confidence interval 29.6 to 46.9). After adjusting for potential confounders, elevated FGF23 was associated with significant direct and indirect effects (mediated through advanced liver fibrosis) on all-cause mortality, with 57% of deaths not mediated through advanced fibrosis.

CONCLUSIONS

In patients with HIV/HCV coinfection, FGF23 may be used as prognostic biomarker for risk stratification accounting also for death causes other than those attributable to liver fibrosis.

Proteomic Correlates of the Urinary Protein/Creatinine Ratio in Heart Failure With Preserved Ejection Fraction

Proteinuria is common in heart failure with preserved ejection fraction (HFpEF), but its biologic correlates are poorly understood. We assessed the relation between 49 plasma proteins and the urinary protein/creatinine ratio (UPCR) in 365 participants in the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist Trial. Linear regression and network analysis were used to represent relations between protein biomarkers and UPCR. Higher UPCR was associated with older age, a greater proportion of female gender, smaller prevalence of previous myocardial infarction, and greater prevalence of diabetes, insulin use, smoking, and statin use, in addition to a lower estimated glomerular filtration rate, hematocrit, and diastolic blood pressure. Growth differentiation factor 15 (GDF-15; β = 0.15, p <0.0001), followed by N-terminal proatrial natriuretic peptide (NT-proANP; β = 0.774, p <0.0001), adiponectin (β = 0.0005, p <0.0001), fibroblast growth factor 23 (FGF-23, β = 0.177; p <0.0001), and soluble tumor necrosis factor receptors I (β = 0.002, p <0.0001) and II (β = 0.093, p <0.0001) revealed the strongest associations with UPCR. Network analysis showed that UPCR is linked to various proteins primarily through FGF-23, which, along with GDF-15, indicated node characteristics with strong connectivity, whereas UPCR did not. In a model that included FGF-23 and UPCR, the former was predictive of the risk of death or heart-failure hospital admission (standardized hazard ratio 1.83, 95% confidence interval 1.49 to 2.26, p <0.0001) and/or all-cause death (standardized hazard ratio 1.59, 95% confidence interval 1.22 to 2.07, p = 0.0005), whereas UPCR was not prognostic. Proteinuria in HFpEF exhibits distinct proteomic correlates, primarily through its association with FGF-23, a well-known prognostic marker in HFpEF. However, in contrast to FGF-23, UPCR does not hold independent prognostic value.

Impact of Impaired Kidney Function on Arrhythmia-Promoting Cardiac Ion Channel Regulation

Chronic kidney disease (CKD) is associated with a significantly increased risk of cardiovascular events and sudden cardiac death. Although arrhythmias are one of the most common causes of sudden cardiac death in CKD patients, the molecular mechanisms involved in the development of arrhythmias are still poorly understood. In this narrative review, therefore, we summarize the current knowledge on the regulation of cardiac ion channels that contribute to arrhythmia in CKD. We do this by first explaining the excitation-contraction coupling, outlining current translational research approaches, then explaining the main characteristics in CKD patients, such as abnormalities in electrolytes and pH, activation of the autonomic nervous system, and the renin-angiotensin-aldosterone system, as well as current evidence for proarrhythmic properties of uremic toxins. Finally, we discuss the substance class of sodium-glucose co-transporter 2 inhibitors (SGLT2i) on their potential to modify cardiac channel regulation in CKD and, therefore, as a treatment option for arrhythmias.

Plasma FGF23 is associated with left atrial remodeling in children on hemodialysis

BACKGROUND

FGF23 mediates cardiac fibrosis through the activation of pro-fibrotic factors in in vitro models and is markedly elevated in kidney disease. Left atrial global longitudinal strain (LA GLS) derived by echocardiographic speckle-tracking measures longitudinal shortening of the LA walls, quantifies atrial performance and may enable detection of early LA remodeling in the setting of normal ventricular function. We hypothesized that LA GLS is abnormal in children on hemodialysis (HD) compared to healthy controls of comparable age/sex distribution and that, among HD patients, greater FGF23 levels are associated with abnormal LA GLS.

METHODS

Clinical and echocardiographic data from 29 children receiving HD and 13 healthy controls were collected in a cross-sectional single-center study. Plasma FGF23 concentrations were measured using ELISA. The primary outcome was LA GLS measured using 2D speckle-tracking strain analysis. Linear regression analysis was used to investigate predictors of LA GLS in HD.

RESULTS

Median dialysis vintage was 1.5 (IQR 0.5-4.3) years. Median intact FGF23 levels were substantially higher in the HD vs. control group (1206 [215, 4707] vs. 51 [43, 66.5] pg/ml; P = 0.0001), and LA GLS was 39.9% SD 11.6 vs. 32.8% SD 5.7 (P = 0.04). Among HD patients, higher FGF23 was associated with lower LA GLS (β per unit Ln-FGF23: - 2.7; 95% CI slope - 5.4, - 0.1; P = 0.04 after adjustment for age, body size, and HD vintage. FGF23 was not associated with LA phasic reservoir, conduit, or contractile strain.

CONCLUSIONS

In children on HD and preserved left ventricular ejection fraction, greater FGF23 is associated with lower LA GLS (indicative of impaired atrial performance). A higher resolution version of the Graphical abstract is available as Supplementary information.

Fibroblast Growth Factor 23: Potential Marker of Invisible Heart Damage in Diabetic Population

Two-dimensional speckle-tracking echocardiography (2DSTE) detects myocardial dysfunction despite a preserved left ventricular ejection fraction. Fibroblast growth factor 23 (FGF23) has become a promising biomarker of cardiovascular risk. This study aimed to determine whether FGF23 may be used as a marker of myocardial damage among patients with diabetes mellitus type 2 (T2DM) and no previous history of myocardial infarction. The study enrolled 71 patients with a median age of 70 years. Laboratory data were analyzed retrospectively. Serum FGF23 levels were determined using a sandwich enzyme-linked immunosorbent assay. All patients underwent conventional echocardiography and 2DSTE. Baseline characteristics indicated that the median time elapsed since diagnosis with T2DM was 19 years. All subjects were divided into two groups according to left ventricular diastolic function. Individuals with confirmed left ventricular diastolic dysfunction had significantly lower levels of estimated glomerular filtration rate and higher values of hemoglobin A1c. Global circumferential strain (GCS) was reduced in the majority of patients. Only an epicardial GCS correlated significantly with the FGF23 concentration in all patients. The study indicates that a cardiac strain is a reliable tool for a subtle myocardial damage assessment. It is possible that FGF23 may become an early diagnostic marker of myocardial damage in patients with T2DM.

Relationship of Fibroblast Growth Factor 23 With Hospitalization for Heart Failure and Cardiovascular Outcomes in Patients Undergoing Cardiac Surgery

Background Fibroblast growth factor 23 (FGF-23) is crucial in regulating phosphate and vitamin D metabolism and is moreover associated with an increased cardiovascular risk. The specific objective of this study was to investigate the influence of FGF-23 on cardiovascular outcomes, including hospitalization for heart failure (HHF), postoperative atrial fibrillation, and cardiovascular death, in an unselected patient population after cardiac surgery. Methods and Results Patients undergoing elective coronary artery bypass graft and/or cardiac valve surgery were prospectively enrolled. FGF-23 blood plasma concentrations were assessed before surgery. A composite of cardiovascular death/HHF was chosen as primary end point. A total of 451 patients (median age 70 years; 28.8% female) were included in the present analysis and followed over a median of 3.9 years. Individuals with higher FGF-23 quartiles showed elevated incidence rates of the composite of cardiovascular death/HHF (quartile 1, 7.1%; quartile 2, 8.6%; quartile 3, 15.1%; and quartile 4, 34.3%). After multivariable adjustment, FGF-23 modeled as a continuous variable (adjusted hazard ratio for a 1-unit increase in standardized log-transformed biomarker, 1.82 [95% CI, 1.34-2.46]) as well as using predefined risk groups and quartiles remained independently associated with the risk of cardiovascular death/HHF and the secondary outcomes, including postoperative atrial fibrillation. Reclassification analysis indicated that the addition of FGF-23 to N-terminal pro-B-type natriuretic peptide provides a significant improvement in risk discrimination (net reclassification improvement at the event rate, 0.58 [95% CI, 0.34-0.81]; P<0.001; integrated discrimination increment, 0.03 [95% CI, 0.01-0.05]; P<0.001). Conclusions FGF-23 is an independent predictor of cardiovascular death/HHF and postoperative atrial fibrillation in individuals undergoing cardiac surgery. Considering an individualized risk assessment, routine preoperative FGF-23 evaluation may improve detection of high-risk patients.

Direct and indirect effects of fibroblast growth factor 23 on the heart

Fibroblast growth factor (FGF)23 is a bone-derived phosphotropic hormone that regulates phosphate and mineral homeostasis. Recent studies have provided evidence that a high plasma concentration of FGF23 is associated with cardiac disease, including left ventricular hypertrophy (LVH), heart failure, atrial fibrillation, and cardiac death. Experimental studies have shown that FGF23 activates fibroblast growth factor receptor 4 (FGFR4)/phospholipase Cγ/calcineurin/nuclear factor of activated T-cells signaling in cardiomyocytes and induces cardiac hypertrophy in rodents. Activation of FGFR4 by FGF23 normally requires the co-receptor α-klotho, and klotho-independent signaling occurs only under conditions characterized by extremely high FGF23 concentrations. Recent studies have demonstrated that FGF23 activates the renin-angiotensin-aldosterone system (RAAS) and induces LVH, at least in part as a result of lower vitamin D activation. Moreover, crosstalk between FGF23 and RAAS results in the induction of cardiac hypertrophy and fibrosis. In this review, we summarize the results of studies regarding the relationships between FGF23 and cardiac events, and describe the potential direct and indirect mechanisms whereby FGF23 induces LVH.

A review of ferric citrate clinical studies, and the rationale and design of the Ferric Citrate and Chronic Kidney Disease in Children (FIT4KiD) trial

Pediatric chronic kidney disease (CKD) is characterized by many co-morbidities, including impaired growth and development, CKD-mineral and bone disorder, anemia, dysregulated iron metabolism, and cardiovascular disease. In pediatric CKD cohorts, higher circulating concentrations of fibroblast growth factor 23 (FGF23) are associated with some of these adverse clinical outcomes, including CKD progression and left ventricular hypertrophy. It is hypothesized that lowering FGF23 levels will reduce the risk of these events and improve clinical outcomes. Reducing FGF23 levels in CKD may be accomplished by targeting two key stimuli of FGF23 production-dietary phosphate absorption and iron deficiency. Ferric citrate is approved for use as an enteral phosphate binder and iron replacement product in adults with CKD. Clinical trials in adult CKD cohorts have also demonstrated that ferric citrate decreases circulating FGF23 concentrations. This review outlines the possible deleterious effects of excess FGF23 in CKD, summarizes data from the adult CKD clinical trials of ferric citrate, and presents the Ferric Citrate and Chronic Kidney Disease in Children (FIT4KiD) study, a randomized, placebo-controlled trial to evaluate the effects of ferric citrate on FGF23 in pediatric patients with CKD stages 3-4 (ClinicalTrials.gov Identifier NCT04741646).

Silver jubilee: 25 years of the first demonstration of the direct effect of phosphate on the parathyroid cell

Although phosphorus is an essential element for life, it is not found in nature in its native state but rather combined in the form of inorganic phosphates (PO₄^3-), with tightly regulated plasma levels that are associated with deleterious effects and mortality when these are out of bounds. The growing interest in the accumulation of PO₄^3- in human pathophysiology originated in its attributed role in the pathogenesis of secondary hyperparathyroidism (SHPT) in chronic kidney disease. In this article, we review the mechanisms by which this effect was justified and we commemorate the important contribution of a Spanish group led by Dr. M. Rodríguez, just 25 years ago, when they first demonstrated the direct effect of PO₄^3- on the regulation of the synthesis and secretion of parathyroid hormone by maintaining the structural integrity of the parathyroid glands in their original experimental model. In addition to demonstrating the importance of arachidonic acid (AA) and the phospholipase A2-AA pathway as a mediator of parathyroid gland response, these findings were predecessors of the recent description of the important role of PO₄^3- on the activity of the calcium sensor-receptor, and also fueled various lines of research on the importance of PO₄^3- overload not only for the pathophysiology of SHPT but also in its systemic pathogenic role.

Novel Biomarkers of Kidney Disease in Advanced Heart Failure: Beyond GFR and Proteinuria

PURPOSE

Kidney disease is a common finding in patients with heart failure and can significantly impact treatment decisions and outcomes. Abnormal kidney function is currently determined in clinical practice using filtration markers in the blood to estimate glomerular filtration rate, but the manifestations of kidney disease in the setting of heart failure are much more complex than this. In this manuscript, we review novel biomarkers that may provide a more well-rounded assessment of kidney disease in patients with heart failure.

RECENT FINDINGS

Galectin-3, ST2, FGF-23, suPAR, miRNA, GDF-15, and NAG may be prognostic of kidney disease progression. L-FABP and suPAR may help predict acute kidney injury (AKI). ST2 and NAG may be helpful in diuretic resistance. Several biomarkers may be useful in determining prognosis of long-term kidney disease progression, prediction of AKI, and development of diuretic resistance. Further research into the mechanisms of kidney disease in heart failure utilizing many of these biomarkers may lead to the identification of therapeutic targets.

Associations between endogenous sex hormones and FGF-23 among women and men in the Multi-Ethnic Study of Atherosclerosis

Elevated levels of testosterone and fibroblast growth factor 23 (FGF-23) are both independently associated with a higher risk of cardiovascular disease (CVD). However, the relationship between sex hormones and FGF-23 is not well established. We explored the association between sex hormones and FGF-23 among middle-aged to older men and women in MESA. We studied 3,052 men and 2,868 postmenopausal women free of CVD at the time of enrollment with baseline serum sex hormones [total testosterone (T), free T, estradiol (E2) and sex hormone binding globulin (SHBG)] and intact FGF-23. In sex-stratified analyses, we examined the cross-sectional associations between log-transformed sex hormones (per 1 SD) and log-transformed FGF-23 using multiple linear regression adjusted for socio-demographics, CVD risk factors, estimated glomerular filtration rate and mineral metabolites (25-hydroxyvitamin D, calcium, phosphorus and parathyroid hormone). The mean (SD) age of study participants was 64 (10) years. The median (IQR) of FGF-23 was similar in women and men [38 (30-46) vs 38 (31-47) pg/mL]. In adjusted analyses, among women, 1 SD increment in free T was associated with 3% higher FGF-23 while SHBG was associated with 2% lower FGF-23. In men, 1 SD increment in E2 was associated with 6% higher FGF-23 whereas total T/E2 ratio was associated with 7% lower FGF-23. In conclusion, this exploratory analysis found that a more androgenic sex hormone profile was directly associated with FGF-23 in women and inversely associated with FGF-23 in men. Longitudinal studies are required to determine whether FGF-23 mediates the relationship between sex hormones and CVD risk.

Abnormalities in Cardiac Structure and Function among Individuals with CKD: The COMBINE Trial

Background

Individuals with CKD have a high burden of cardiovascular disease (CVD). Abnormalities in cardiac structure and function represent subclinical CVD and can be assessed by cardiac magnetic resonance imaging (cMRI).

Methods

We investigated differences in cMRI parameters in 140 individuals with CKD stages 3b-4 who participated in the CKD Optimal Management with BInders and NicotinamidE (COMBINE) trial and in 24 age- and sex-matched healthy volunteers. Among COMBINE participants, we examined the associations of eGFR, urine albumin-creatinine ratio (UACR), phosphate, fibroblast growth factor 23 (FGF23), and parathyroid hormone (PTH) with baseline (N=140) and 12-month change (N=112) in cMRI parameters.

Results

Mean (SD) ages of the COMBINE participants and healthy volunteers were 64.9 (11.9) and 60.4 (7.3) years, respectively. The mean (SD) baseline eGFR values in COMBINE participants were 32.1 (8.0) and 85.9 (16.0) ml/min per 1.73 m² in healthy volunteers. The median (interquartile range [IQR]) UACR in COMBINE participants was 154 (20.3-540.0) mg/g. Individuals with CKD had lower mitral valve E/A ratio compared with healthy volunteers (for CKD versus non-CKD, β estimate, -0.13; 95% CI, -0.24 to -0.012). Among COMBINE participants, multivariable linear regression analyses showed that higher UACR was significantly associated with lower mitral valve E/A ratio (β estimate per 1 unit increase in natural-log UACR, -0.06; 95% CI, -0.09 to -0.03). This finding was preserved among individuals without baseline CVD. UACR was not associated with 12-month change in any cMRI parameter. eGFR, phosphate, FGF23, and PTH were not associated with any cMRI parameter in cross-sectional or change analyses.

Conclusions

Individuals with CKD stages 3b-4 have evidence of cMRI abnormalities. Albuminuria was independently associated with diastolic dysfunction, as assessed by mitral valve E/A ratio, in individuals with CKD with and without clinical CVD. Albuminuria was not associated with change in any cMRI parameter.

An Overview of FGF-23 as a Novel Candidate Biomarker of Cardiovascular Risk

Fibroblast growth factor-23 (FGF)-23 is a phosphaturic hormone involved in mineral bone metabolism that helps control phosphate homeostasis and reduces 1,25-dihydroxyvitamin D synthesis. Recent data have highlighted the relevant direct FGF-23 effects on the myocardium, and high plasma levels of FGF-23 have been associated with adverse cardiovascular outcomes in humans, such as heart failure and arrhythmias. Therefore, FGF-23 has emerged as a novel biomarker of cardiovascular risk in the last decade. Indeed, experimental data suggest FGF-23 as a direct mediator of cardiac hypertrophy development, cardiac fibrosis and cardiac dysfunction via specific myocardial FGF receptor (FGFR) activation. Therefore, the FGF-23/FGFR pathway might be a suitable therapeutic target for reducing the deleterious effects of FGF-23 on the cardiovascular system. More research is needed to fully understand the intracellular FGF-23-dependent mechanisms, clarify the downstream pathways and identify which could be the most appropriate targets for better therapeutic intervention. This review updates the current knowledge on both clinical and experimental studies and highlights the evidence linking FGF-23 to cardiovascular events. The aim of this review is to establish the specific role of FGF-23 in the heart, its detrimental effects on cardiac tissue and the possible new therapeutic opportunities to block these effects.