GSTM1 and anemia: ADHF: acute decompensated heart failure; AHF: acute heart failure; CT: control; FCM: ferric carboxymaltose; Hb: hemoglobin; HF: heart failure; ID: iron deficiency; IDA: iron deficiency anemia; IV: intravenous; IT: iron therapy; LVEF: low ventricular ejection fraction; NA: not available; RCT: randomized controlled trial; SFGC: sodium ferric gluconate complex; NTproBNP: N-terminal pro-B-type natriuretic peptide; TSAT: transferrin saturation