Use of serum fibroblast growth factor 23 vs. plasma B-type natriuretic peptide levels in assessing the pathophysiology of patients with heart failure

Recently, fibroblast growth factor 23 (FGF23), a phosphate-regulating hormone, has been linked to the pathophysiology of heart failure (HF), thus encouraging us to examine which hemodynamic abnormalities of HF are linked to either serum FGF23 or plasma B-type natriuretic peptide (BNP) levels. We measured both the serum FGF23 and plasma BNP levels in 154 consecutive prospectively enrolled hospitalized HF patients, with an estimated glomerular filtration rate >40 ml min^-1 1.73 m^-2, who underwent heart catheterizations and an echocardiogram. The serum FGF23 levels correlated with the diameter of the inferior vena cava and its respiratory changes, whereas the plasma BNP levels did not. Both the plasma BNP and serum FGF23 levels were moderately correlated with the mean pulmonary artery (PA) pressure and pulmonary capillary wedge (PCW) pressure. Interestingly, in patients with an above-median right-atrial (RA) pressure (4 mm Hg), FGF23 levels were correlated with both PA and PCW pressures, but the levels were not correlated in patients with a below-median RA pressure. In contrast, the plasma BNP levels were correlated with both PA and PCW pressures. Finally, serum FGF23 levels, compared with the plasma BNP levels, were more strongly associated with the clinical outcomes in patients with above-median RA pressure. These findings suggested that serum FGF23 levels are predominantly correlated with clinical outcomes, may serve as a biomarker for HF in patients with higher RA pressure, may provide beneficial information for patients with right-sided HF and may represent different clinical information than that provided only by plasma BNP levels.