Inclusion Criteria:  Mentally competent with age ≥ 70 years Elective AVR or CABG surgery Expected uncomplicated postoperative trajectory, defined as: No inotropic agents or ventilation at time of final inclusion (POD 1) Expected discharge to general ward at POD 1 Moderate postoperative IDA, defined as: Hb between 85 and 110 g/L and Ferritin <100 µg/L or Iron saturation (TSAT) < 20%  Exclusion Criteria:  Medical history of iron overload/haemochromatosis Medical history of liver cirrhosis or ALT/AST value in blood serum triple of normal value (female patients: ALT >120, AST >105 U/L. Male patients: ALT>150, AST>135 U/L) Severe renal failure (eGFR<15ml/min/1.73m2) Recent treatment with IVI (<12 weeks prior) Serious or severe allergic reaction to IVI in medical history Severe asthma or eczema in medical history (atopic constitution)