Mineral metabolism in heart disease

Fibroblast growth factor-23 as a biomarker of adverse outcomes in patients with coronary artery disease: A meta-analysis

BACKGROUND

Fibroblast growth factor-23 (FGF-23) level has been linked the adverse outcomes in patients with coronary artery disease (CAD). The purpose of this meta-analysis was to assess the predictive value of blood FGF-23 level in CAD patients.

METHODS

Two authors comprehensively searched PubMed and Embase until August 20, 2021 to identify studies investigating the association of FGF-23 level with adverse outcomes in CAD patients. Outcomes of interest were major adverse cardiovascular events (MACEs), cardiovascular or all-cause mortality.

RESULTS

Eight studies with 16,702 patients with CAD were identified. Pooled results showed that elevated FGF-23 level was associated with higher risk of MACEs (risk ratio [RR] 1.56; 95% confidence intervals [CI] 1.32-1.84), cardiovascular mortality (RR 1.99; 95% CI 1.38-2.86) and all-cause mortality (RR 1.95; 95% CI 1.67-2.27) after adjusted confounding factors. In addition, per doubling increase in FGD-23 level was associated with 24% higher risk of MACEs. Each standard deviation increases in FGD-23 level conferred a 36% higher risk of cardiovascular mortality.

CONCLUSIONS

Elevated blood FGF-23 level is associated with higher risk of MACEs, cardiovascular or all-cause mortality in patients with CAD, even after adjustment for renal function. Blood FGF-23 level may provide important predictive information in CAD patients.

Does a rise in plasma erythropoietin after high-altitude exposure affect FGF23 in healthy volunteers on a normal or low-phosphorus diet?

BACKGROUND AND AIMS

Data of experimental rodent models suggest that hypoxia with subsequent increase in erythropoietin stimulates the expression of the phosphaturic hormone fibroblast growth factor 23 (FGF23).

METHODS AND RESULTS

To translate the findings of animal studies into human physiology, herein we exposed eight healthy volunteers to high altitude (2656 m above sea level) for four days. The volunteers were randomized on a low-phosphorous diet (n = 4) or a normal phosphorus diet (n = 4). Although high-altitude exposure caused a significant increase in plasma erythropoietin (EPO) (before high-altitude exposure: low phosphorus: median EPO 6.6 mIU/ml [interquartile range (IQR) 6.0; 8.2], normal phosphorus: median EPO 9.0 mIU/ml [IQR 7.9; 11.5]; at day 2: low phosphorus: median EPO 21.3 mIU/ml [IQR 19.5; 23.8], normal phosphorus: median EPO 19.4 mIU/ml [IQR 18.0; 20.8]), there was no consistent increase in plasma c-terminal FGF23 or plasma intact FGF23. We observed only a single, intermittent peak in c-terminal FGF23 levels after 5 h of maximal aerobic exercise.

CONCLUSION

These data do not support a substantial effect of moderate hypoxia alone on the expression of FGF23, but they suggest that combined exercise and high-altitude exposure may temporarily induce FGF23 expression.

Current and Potential Therapeutic Strategies for Hemodynamic Cardiorenal Syndrome

BACKGROUND

Cardiorenal syndrome (CRS) encompasses conditions in which cardiac and renal disorders co-exist and are pathophysiologically related. The newest classification of CRS into seven etiologically and clinically distinct types for direct patient management purposes includes hemodynamic, uremic, vascular, neurohumoral, anemia- and/or iron metabolism-related, mineral metabolism-related and protein-energy wasting-related CRS. This classification also emphasizes the pathophysiologic pathways. The leading CRS category remains hemodynamic CRS, which is the most commonly encountered type in patient care settings and in which acute or chronic heart failure leads to renal impairment.

SUMMARY

This review focuses on selected therapeutic strategies for the clinical management of hemodynamic CRS. This is often characterized by an exceptionally high ratio of serum urea to creatinine concentrations. Loop diuretics, positive inotropic agents including dopamine and dobutamine, vasopressin antagonists including vasopressin receptor antagonists such as tolvaptan, nesiritide and angiotensin-neprilysin inhibitors are among the pharmacologic agents used. Additional therapies include ultrafiltration (UF) via hemofiltration or dialysis. The beneficial versus unfavorable effects of these therapies on cardiac decongestion versus renal blood flow may act in opposite directions. Some of the most interesting options for the outpatient setting that deserve revisiting include portable continuous dobutamine infusion, peritoneal dialysis and outpatient UF via hemodialysis or hemofiltration.

KEY MESSAGES

The new clinically oriented CRS classification system is helpful in identifying therapeutic targets and offers a systematic approach to an optimal management algorithm with better understanding of etiologies. Most interventions including UF have not shown a favorable impact on outcomes. Outpatient portable dobutamine infusion is underutilized and not well studied. Revisiting traditional and novel strategies for outpatient management of CRS warrants clinical trials.