FGF23 and heart failure: These results mirror our observations in a previous study on cardiac remodeling in the 5/6 nephrectomy rat model of CKD in which inhibition of the FGF23–FGFR4–calcineurin–nuclear factor of activated T cells signaling pathway prevented cardiac remodeling without altering serum phosphate levels.13,15,16,27 Taken together, these findings argue against a major FGF23-independent role of phosphate in driving heart failure in CKD, but further studies are warranted to explore potentially toxic interactions between elevated phosphate and FGF23, as occurs in CKD.