LVEF: left ventricular ejection fraction; Hb: hemoglobin; NYHA: New York Heart Association; TSAT: transferrin saturation; NT-proBNP: N-terminal-prohormone brain natriuretic peptide; FCM: ferric carboxymaltose; CRP: C-reactive protein; HF: heart failure. Here, NPPB is linked to heart failure.