Background: Numerous studies have shown associations between fibroblast growth factor 23 (FGF23) and cardiovascular outcome. While strong associations with cardiovascular morbidity and mortality have been reported in patients with heart failure (HF), less is known about associations between FGF23 and outcome in patients with myocardial infarction (MI).

Methods: FGF23 levels were assessed in 180 patients admitted to the Intermediate Care Unit of University Hospital Aachen for acute MI, 99 of whom presenting with concomitant acute HF and 81 without HF. All patients were followed-up for one year, and outcome estimates by FGF23 were compared to GRACE Score estimates in MI patients with and without concomitant HF.

Results: In the entire cohort of 180 patients with acute MI, 14 patients did not survive the one-year follow-up period (8 patients with HF and 6 patients without HF). Log-transformed serum levels of intact FGF23 (logFGF23) did not differ between MI patients with and without HF at admission (1.60 ± 0.26 vs. 1.60 ± 0.22; p=0.82), and no difference in logFGF23 was observed between MI patients who died and those who survived (1.75 ± 0.33 vs. 1.59 ± 0.23), neither in the unadjusted analysis (p=0.10), nor when accounting for the impact of age, sex, and eGFR in generalized mixed model analysis (p=0.38). However, when only MI patients with concomitant acute HF were considered, we observed significantly higher logFGF23 among non-survivors compared to survivors (1.90 ± 0.33 vs. 1.58 ± 0.24; p=0.009), and the difference was robust after adjusting for age, sex, and eGFR (p=0.02). While higher logFGF23 was not associated with one-year outcome in the entire cohort, logFGF23 was fairly predictive for one-year mortality in patients with concomitant HF (AUC 0.78; 95%CI 0.61–0.95), where it outperformed GRACE Score estimates (AUC 0.70; 95%CI 0.46–0.94).

Conclusion: In patients with acute MI, serum levels of FGF23 were associated with one-year mortality only in those patients who concomitantly presented with HF, whereas no associations were observed in MI patients without HF despite similar FGF23 serum levels at admission. Further studies are warranted to investigate whether FGF23 plays a causative role in dismal outcome of HF.