Elevation of circulating but not myocardial FGF23 in human acute decompensated heart failure

Background Elevated plasma fibroblast growth factor 23 (FGF23) is a prognostic marker in chronic kidney disease. Recently, FGF23 was reported to also be a predictive factor in chronic congestive heart failure (HF). To date however, plasma levels in acute decompensated HF (ADHF) have not been reported and myocardial production and distribution of FGF23 in HF is poorly defined. We aimed to determine plasma levels and myocardial production of FGF23 in ADHF. Methods Plasma FGF23, N-terminal pro B-type natriuretic peptide (NT-proBNP) and estimated glomerular filtration rate (eGFR) were assessed in 21 ADHF patients and 19 controls. Myocardial gene expression and distribution of FGF23 was determined on left ventricular samples from HF patients and normal controls. Results Plasma FGF23 was markedly higher in ADHF patients compared with controls (1498 ± 1238 versus 66 ± 27 RU/mL, P < 0.0001). There were no correlations between FGF23 and eGFR, NT-proBNP, ejection fraction or age. ADHF subjects with eGFR >60 mL/min/1.73 m² had FGF23 levels of 1526 ± 1601 RU/mL versus 55 ± 20 RU/mL in controls (P = 0.007). Quantified myocardial FGF23 gene expression was similar between HF patients and controls. Myocardial FGF23 immunostaining was similar between HF patients and controls, with equal distribution throughout cardiomyocytes. Conclusion Patients with ADHF had markedly elevated plasma FGF23 levels. Myocardial FGF23 gene expression was present in HF at a similar level as normal controls, and immunohistochemistry showed similar cellular distribution of FGF23 in HF and controls, suggesting that the myocardium does not contribute to the elevated circulating FGF23 in HF.