Intravenous iron does not effectively correct preoperative anaemia in cardiac surgery: a pilot randomized controlled trial

OBJECTIVES: Preoperative anaemia is a strong predictor of blood transfusion requirements and must be assessed for appropriate optimization before elective surgery. Iron therapy is a transfusion-sparing approach effective for increasing haemoglobin concentrations. However, its role in elective cardiac surgery and the optimal route of administration remain unknown. This single-centre, non-blinded, randomized, controlled trial compared the effectiveness of intravenous ferric carboxymaltose therapy with oral iron for anaemic patients undergoing elective cardiac surgery.

METHODS: Fifty anaemic patients scheduled for elective cardiac surgery were randomized to receive either oral or intravenous iron therapy 3-8 weeks preoperatively. Changes in haemoglobin concentration were measured. Blood transfusion and postoperative outcome data were collected.

RESULTS: Preoperative median increases in haemoglobin were 1.0 g/l (interquartile range -3.25 to 7.25 g/l) and 3.0 g/l (interquartile range -1.25 to 6.25 g/l) for patients receiving intravenous and oral iron, respectively (P = 0.42). The median first 12-h blood loss was significantly higher in the intravenous group (655 ml; interquartile range 162-1540 ml) compared to the oral group (313 ml; interquartile range 150-1750 ml; P < 0.007). Median increments in serum ferritin were superior for the intravenous group (median difference 313 µg/l; interquartile range 228-496) compared to the oral group (median difference 5.5 µg/l; interquartile range -1.4 to 19.4; P < 0.001).

CONCLUSIONS: Increases in ferritin after intravenous iron administration were significantly greater than those after oral iron administration. There was no significant difference in haemoglobin increments between groups. Despite significantly higher intraoperative blood loss in the group receiving intravenous iron, blood transfusion requirements for both groups were not statistically different.

Clinical trial registration: ISRCTN22158788.