Abstract 9902: Serum FGF23 Concentration is Associated With Cardiac Hypertrophy and Decreased Systolic Function Among Both CKD and Non-CKD Cardiac Patients

Introduction: Purpose: Serum concentrations of fibroblast growth factor-23 (FGF23) are increased in response to elevated serum phosphate levels among patients with renal dysfunction. Besides regulating circulating phosphate levels, FGF23 may induce cardiac hypertrophy; thus, enhanced FGF23 excretion may underlie the heart failure observed among patients with chronic kidney disease (CKD). Here we examined whether FGF23 concentrations are associated with cardiac hypertrophy among cardiac patients regardless of the presence or absence of CKD. Methods: The present study enrolled 480 cardiac patients admitted to our cardiology department between January 2012 and December 2012. Serum FGF23 level was measured by an ELISA method. Left ventricular mass index (LVMI) was used as a marker of cardiac hypertrophy. Results: Of the 480 patients, 132 (27.5%) had an estimated glomerular filtration rate (eGFR) of <60 mL/min/m2 (no-CKD group) and the remaining 348 (72.5%) had an eGFR of 60 or greater (CKD group). FGF23 was correlated with eGFR in the CKD group, but not in the no-CKD group. Stepwise multivariate linear regression analysis was performed using LVMI as a dependent variable, and sex, age, eGFR, serum calcium and phosphate, and log(FGF23) as independent variables. Log(FGF23) was selected as an independent variable that had a significant association with LVMI with a standardized correlation coefficient of 0.26 in the no-CKD group (P<0.01) and 0.25 in the CKD group (P<0.01). When left ventricular ejection fraction was used as an independent variable in this model, log(FGF23) was selected as significant predictor with a standardized correlation coefficient of -0.20 in the no-CKD group (P<0.05) and -0.18 in the CKD group (P<0.01). Conclusions: Among cardiac patients, serum FGF23 concentration was associated positively with left ventricular mass and negatively with left ventricular ejection fraction not only in patients with CKD, but also in those without CKD.