Coexistence of low vitamin D and high fibroblast growth factor-23 plasma levels predicts an adverse outcome in patients with coronary artery disease

Abstract

Objective: Vitamin D and fibroblast growth factor-23 (FGF-23) are related with cardiovascular disorders. We have investigated the relationship of calcidiol (vitamin D metabolite) and FGF-23 plasma levels with the incidence of adverse outcomes in patients with coronary artery disease.

Methods: Prospective follow-up study of 704 outpatients, attending the departments of Cardiology of four hospitals in Spain, 6-12 months after an acute coronary event. Baseline calcidiol, FGF-23, parathormone, and phosphate plasma levels were assessed. The outcome was the development of acute ischemic events (any acute coronary syndrome, stroke, or transient ischemic attack), heart failure, or death. Cox regression adjusted for the main confounders was performed.

Results: Calcidiol levels showed a moderate-severe decrease in 57.3% of cases. Parathormone, FGF-23, and phosphate levels were increased in 30.0%, 11.5% and 0.9% of patients, respectively. Only 22.4% of patients had glomerular filtration rate<60 ml/min1.73 m2. After a mean follow-up was 2.15±0.99 years, 77 patients developed the outcome. Calcidiol (hazard ratio [HR] = 0.67; 95% confidence interval [CI] = 0.48-0.94; p = 0.021) and FGF-23 (HR = 1.13; 95% CI = 1.04-1.23; p = 0.005) plasma levels predicted independently the outcome. There was a significant interaction between calcidiol and FGF-23 levels (p = 0.025). When the population was divided according to FGF-23 levels, calcidiol still predicted the outcome independently in patients with FGF-23 levels higher than the median (HR = 0.50; 95% CI = 0.31-0.80; p = 0.003) but not in those with FGF-23 levels below this value (HR = 1.03; 95% CI = 0.62-1.71; p = 0.904).

Conclusions: Abnormalities in mineral metabolism are frequent in patients with stable coronary artery disease. In this population, low calcidiol plasma levels predict an adverse prognosis in the presence of high FGF-23 levels.

Figure 1. Kaplan-Meier survival curves showing the differences in outcome in the whole population.

Low calcidiol (left) and high FGF-23 (right) plasma levels are associated with a worse prognosis.

Figure 2. Kaplan-Meier survival curves showing the differences in outcome as predicted by calcidiol in population subgroups according to FGF-23 plasma levels.

In patients with FGF-23 lower than or equal to the median (69.9 RU/mL), calcidiol plasma levels are no longer associated with prognosis (left). However, calcidiol levels are still strongly associated with a worse prognosis in the subgroup with FGF-23 levels above the median (right).