Serum Levels of Irisin Are Positively Associated with Improved Cardiac Function in Patients with Heart Failure with Reduced Ejection Fraction

<b>Background</b>: The purpose of the study is to investigate a possible predictive value of irisin for improved left ventricular (LV) ejection fraction (EF) in discharged patients with known heart failure with reduced ejection fraction (HFrEF). <b>Methods</b>: We included in the study 313 patients who were discharged with HFrEF (at admission, LVEF ≤ 40%) and monitored for 3 months. HF with improved LVEF (HFimpEF) was characterized as a >40% increase in LVEF on transthoracic B-mode echocardiography within 3 months of follow-up. Circulating biomarkers including NT-proBNP and irisin were detected at baseline and after 3 months of observation. By the third month, 117 (37.4%) patients had HFimpEF, whereas 196 individuals were categorized as having persistent HFrEF. <b>Results</b>: We found that HFimpEF was related to lower LV end-diastolic dimensions and concentrations of NT-proBNP and higher left atrial volume index (LAVI) and irisin concentrations than those with persistent HFrEF. The most balanced cut-offs of irisin and NT-proBNP concentrations (improved LVEF versus non-improved LVEF) were 10.8 ng/mL and 1540 pmol/L, respectively. Multivariate regression analysis showed that atrial fibrillation (odds ratio [OR] = 0.95; <i>p</i> = 0.010), LAVI < 39 mL/m² (OR = 1.23; <i>p</i> = 0.001), irisin levels ≥ 10.8 ng/mL (OR = 1.73; <i>p</i> = 0.001), and NT-proBNP < 1540 pmol/mL (OR = 1.47; <i>p</i> = 0.001) independently predicted HFimpEF. The discriminative ability of irisin ≥ 10.8 ng/mL was better than NT-proBNP < 1540 pmol/mL; the predictive ability of irisin alone was not improved by the combined model (irisin added to NT-proBNP). <b>Conclusions</b>: serum irisin ≥ 10.8 ng/mL predicted HFimpEF independently of natriuretic peptide in HFrEF patients.