Intravenous iron before heart surgery cuts transfusion needs

Giving intravenous iron to patients with anemia before heart surgery reduces the need for a red blood transfusion and results in an extra day at home in the first 90 days after surgery, finds a clinical trial published by The BMJ today. 

Intravenous iron also saved approximately 44 units of blood products for every 100 patients treated. 

A third of patients undergoing cardiac surgery are anemic and 20-50% receive a blood transfusion after surgery, which is linked to increased risks of complications, longer hospital stays, and death after surgery.

Previous studies suggest that intravenous iron before surgery boosts hemoglobin levels (the protein in red blood cells that carries oxygen around the body) and may reduce the need for transfusion, but there is currently no evidence to show that this improves outcomes that matter to patients. 

To address this gap, researchers enrolled 955 adults with anemia (average age 66 years; 60% male) undergoing elective cardiac surgery across 33 hospitals in 10 countries between 15 July 2016 and 15 December 2023. 

Patients with inherited blood disorders, those having kidney dialysis or who had intravenous iron given in the previous four weeks were excluded. Other factors such as age, sex, ethnicity, and pre-existing conditions were also taken into account. 

Participants were randomly assigned to either intravenous iron or placebo 1-26 weeks before surgery and the number of days alive and at home up to 90 days after surgery was recorded. Other outcomes included red cell transfusion and postoperative complications.

Of 921 patients assessed, the average number of days alive and at home up to 90 days after surgery in patients assigned to intravenous iron was 81 and in patients receiving placebo was 80. 

Red blood cell transfusions were given to 262 patients (61%) in the iron group and 302 patients (68%) in the placebo group during their hospital stay. There were no differences in major complications or length of hospital stay.

The researchers acknowledge several limitations. For example, they enrolled patients with anemia but did not require confirmation of absolute iron deficiency and say a one day difference in a 90 day recovery period is in itself a very small treatment effect. 

However, study strengths included a low drop-out rate and measurement of patient-centred outcomes such as quality of recovery, days at home, and quality of life. Findings were also consistent after further analyses, suggesting they are robust. 

As such, they conclude: "This study shows that intravenous iron repletion in patients with anemia before cardiac surgery increased preoperative haemoglobin concentration, reduced the need for red cell transfusion, and resulted in an extra day at home in the first 90 days after surgery."

Intravenous iron also saved approximately 44 units of blood products for every 100 patients treated, they add.