Plasma levels of free fatty acid differ in patients with left ventricular preserved, mid-range, and reduced ejection fraction

BACKGROUND: Free fatty acids (FFAs) predicted the risk of heart failure (HF) and were elevated in HF with very low left ventricular ejection fraction (LVEF) compared to healthy subjects. The aim of this study was to investigate whether total levels of FFA in plasma differed in patients with HF with preserved (HFpEF), mid-range (HFmrEF), and reduced ejection fraction (HFrEF) and the association with the three categories. METHODS: One hundred thirty-nine patients with HFpEF, HFmrEF and HFrEF were investigated in this study. Plasma FFA levels were measured using commercially available assay kits, and LVEF was calculated by echocardiography with the Simpson biplane method. Dyspnea ranked by New York Heart Association (NYHA) was also identified. RESULTS: FFA concentrations were higher in HFrEF than in HFmrEF and HFpEF, respectively (689 ± 321.5 μmol/L vs. 537.9 ± 221.6 μmol/L, p = 0.036; 689 ± 321.5 μmol/L vs. 527.5 ± 185.5 μmol/L, p = 0.008). No significant differences in FFA levels were found between HFmrEF and HFpEF (537.9 ± 221.6 μmol/L vs. 527.5 ± 185.5 μmol/L, p = 0.619). In addition, we found a negative correlation between FFA levels and LVEF (regression coefficient: - 0.229, p = 0.004) and a positive correlation between FFAs and NYHA class (regression coefficient: 0.214, p = 0.014) after adjustment for clinical characteristic, medical history and therapies. ROC analysis revealed that FFAs predicted HFrEF across the three categories (AUC: 0.644, p = 0.005) and the optimal cut-off level to predict HFrEF was FFA levels above 575 μmol/L. CONCLUSIONS: FFA levels differed across the three categories, which suggests that energy metabolism differs between HFpEF, HFmrEF and HFrEF.