Background Elevation of FGF23 (fibroblast growth factor 23) and decreased Klotho levels have been associated with various cardiovascular and renal diseases. However, the combined study of the FGF23–Klotho axis in ischemic heart disease remains elusive. Methods We analyzed the associations between circulating FGF23 and Klotho levels with cardiac and renal parameters, as well as mortality outcomes following myocardial infarction (MI). Cardiac tissue from patients with ischemic heart disease and a post‐MI mouse model were analyzed to assess myocardial FGF23 expression. Proteomic analysis was performed to examine myocardial pathways activated by FGF23 and regulated by Klotho. Results We observed an inverse correlation between circulating levels of FGF23 and Klotho in patients after MI. Elevated plasma FGF23 levels were particularly associated with ST‐segment–elevation MI and cardiac dysfunction, including reduced left ventricular ejection fraction, prolonged corrected interval, and higher Killip–Kimball classification of cardiac risk, identifying FGF23 as a potential prognostic marker of overall and cardiac‐related mortality. In contrast, systemic Klotho levels were reduced in patients with ST‐segment–elevation MI but did not correlate with mortality. In cardiac tissue, ischemic injury significantly upregulated FGF23 expression. Although Klotho prevented FGF23‐induced proteomic alterations, it did not inhibit cardiac FGF23 overexpression in the post‐MI model. Conclusions FGF23 represents a promising biomarker for mortality and cardiac dysfunction in patients with MI. Although Klotho does not appear to be a reliable predictor of mortality after MI, its cardioprotective properties suggest a role in modulating FGF23‐driven metabolic, structural, and proliferative processes in the myocardium.
Vázquez‐Sánchez et al. (Thu,) studied this question.