Effect of (short-term) intravenous iron supplementation in iron-deficient non-anaemic cardiac surgical patients on perioperative outcome.

BACKGROUND: While intravenous iron improves outcomes in anaemic surgical patients, the impact of iron deficiency (ID) and its treatment in non-anaemic patients remains unclear. METHODS: In this single-centre retrospective analysis, non-anaemic ID patients (age ≥ 18 years) undergoing major cardiac surgery at the University Hospital Frankfurt were included. Primary endpoints were red blood cell (RBC) transfusion rate and use of RBC units. Secondary endpoints were increase in haemoglobin levels and postoperative outcome (mortality, length of stay, mechanical ventilation, laboratory values). Patients were assigned to the following groups: No-Iron (no anaemia, ID, and no iron supplementation) and Iron (anaemia, ID, and iron supplementation). RESULTS: A total of 3605 patients were screened, of whom 2345 were non-anaemic. Six hundred ninety-eight non-anaemic ID patients were included in the analysis, of whom 90 received intravenous iron supplementation. The overall RBC transfusion rate (43.6% [95% CI: 39.6-47.6] versus 50.0% [95% CI: 39.9-60.1]) and number of transfused blood units (2.0 [IQR: 1.0; 4.0] versus 2.0 [IQR: 1.0; 4.0]) were similar between patients of the No-Iron and Iron groups. Hospital length of stay, mortality, and postoperative complications were similar in both groups. When applying stricter cutoff values to define ID (ferritin < 30 μg/l), a trend toward reduced transfusion rates was observed: total RBC transfusion rate was 50.0% (95% CI: 34.9-65.2) in the No-Iron group and 42.9% (95% CI: 26.8-60.5) in the Iron group. In the case of short-term (1 day prior to surgery) iron supplementation, RBC unit utilisation and postoperative outcomes were comparable between the two groups. CONCLUSION: In non-anaemic cardiac surgery patients, (short-term) preoperative intravenous iron supplementation showed no significant impact on RBC transfusion rate, haemoglobin levels, or postoperative outcomes. However, a stricter definition of ID revealed a trend toward reduced transfusion rates.