High-dose intravenous iron significantly reduces the risk of red blood cell transfusion and improves postoperative hemoglobin levels after cardiac surgery: A systematic review of randomized controlled trials

Background: High-dose intravenous iron supplementation offers substantial hematologic protective benefits in clinical practice; however, its efficacy in enhancing blood protection during cardiac surgery remains uncertain. The present study aimed to investigate the effects and safety of high-dose intravenous iron as an optimal blood management strategy for patients undergoing cardiac procedures. Methods: Major databases, including PubMed, Embase, and Cochrane, were searched on June 20, 2025, for randomized controlled trials (RCTs) comparing red blood cell transfusion rates in adult patients undergoing high-dose intravenous iron supplementation versus those receiving control therapy (placebo) following cardiac surgery. The secondary outcome measures included postoperative hemoglobin levels, length of hospital stay, and incidence of adverse events. Results: Seven RCTs involving 975 subjects were identified in the database search. Compared with the control group (placebo), high-dose intravenous iron significantly decreased the rate of postoperative red blood cell transfusion among patients undergoing cardiac surgery (risk ratio 0.69, 95% confidence interval [CI] 0.52–0.91, P = 0.009, I2 = 61%, n = 975, certainty of evidence: moderate). Furthermore, one week or more following surgery, administration of high-dose intravenous iron resulted in a significant increase in postoperative hemoglobin levels (mean difference 0.71, 95% CI 0.41 to 1.01, P