Bone marrow and plasma FGF-23 in heart failure patients: novel insights into the heart-bone axis

Fibroblast growth factor 23 (FGF-23) is known to be elevated in patients with congestive heart failure (CHF). As FGF-23 is expressed in the bone but can also be expressed in the myocardium, the origin of serum FGF-23 in CHF remains unclear. It is also unclear if FGF-23 expressed in the bone is associated with outcome in CHF. The aim of the present study was to investigate FGF-23 levels measured in bone marrow plasma (FGF-23-BM) and in peripheral blood (FGF-23-P) in CHF patients to gain further insights into the heart-bone axis of FGF-23 expression. We also investigated possible associations between FGF-23-BM as well as FGF-23-P and outcome in CHF patients.

We determined FGF-23-P and FGF-23-BM levels in 203 CHF patients (85% male, mean age 61.3 years) with a left ventricular ejection fraction (LVEF) ≤45% and compared them with those of 48 healthy controls (48% male, mean age 39.2 years). We investigated the association between FGF-23-BM and FGF-23-P with all-cause mortality in CHF patients, 32 events, median follow-up 1673 days, interquartile range [923, 1828]. FGF-23-P (median 60.3 vs. 22.0 RU/mL, P < 0.001) and FGF-23-BM (median 130.7 vs. 93.1 RU/mL, P < 0.001) levels were higher in CHF patients compared with healthy controls. FGF-23-BM levels were significantly higher than FGF-23-P levels in both CHF patients and in healthy controls (P < 0.001). FGF-23-P and FGF-23-BM correlated significantly with LVEF (r = -0.37 and r = -0.33, respectively), N terminal pro brain natriuretic peptide levels (r = 0.57 and r = 0.6, respectively), New York Heart Association status (r = 0.28 and r = 0.25, respectively), and estimated glomerular filtration rate (r = -0.43 and r = -0.41, respectively) (P for all <0.001) and were independently associated with all-cause mortality in CHF patients after adjustment for LVEF, estimated glomerular filtration rate, New York Heart Association status, and N terminal pro brain natriuretic peptide, hazard ratio 2.71 [confidence interval: 1.18-6.20], P = 0.018, and hazard ratio 2.80 [confidence interval: 1.19-6.57], P = 0.018, respectively.

In CHF patients, FGF-23 is elevated in bone marrow plasma and is independently associated with heart failure severity and all-cause mortality. The failing heart seems to interact via FGF-23 within a heart-bone axis.