Circulating Fibroblast Growth Factor‐23 and the Incidence of Atrial Fibrillation: The Atherosclerosis Risk in Communities Study

BACKGROUND: Increased concentrations of circulating fibroblast growth factor 23 (FGF‐23) have been associated with higher risk of cardiovascular disease. The association between FGF‐23 and the risk of atrial fibrillation (AF), a common arrhythmia, is less defined. Thus, we explored whether FGF‐23 concentration was associated with AF incidence in a large community‐based cohort. METHODS AND RESULTS: We studied 12 349 men and women enrolled in the Atherosclerosis Risk in Communities (ARIC) study, without prevalent AF at baseline in 1990–1992. Serum intact FGF‐23 concentration was measured with the Kainos 2‐site ELISA. Incident AF through 2010 was ascertained from study ECGs and hospital discharge codes. Cox proportional hazards models adjusted for potential confounding factors, including kidney function, were used to estimate the association between FGF‐23 and AF risk. We identified 1572 AF events during a mean follow‐up of 17 years. In multivariable analysis, a difference of 1 SD (16 pg/mL) in baseline FGF‐23 was not associated with the risk of AF (hazard ratio [HR], 1.04; 95% confidence interval [CI], 0.99, 1.09). Results were similar when FGF‐23 was modeled in quartiles (HR, 1.09; 95% CI, 0.94, 1.26, comparing extreme quartiles). Reduced kidney function was associated with increased AF risk across quartiles of FGF‐23 levels. CONCLUSION: In this large community‐based cohort, baseline FGF‐23 levels were not associated with AF risk independently of kidney function. Our results do not support a major role for FGF‐23 as a risk factor for AF or as a mediator of the association between chronic kidney disease and AF.