Perioperative anemia is common in cardiac surgery. Few studies investigated the effect of postoperative intravenous (IV) iron supplementation and were mostly inconclusive.

Design: A randomized single-center, double-blind, placebo-controlled, parallel-group trial. Participants: 195 non-anemic patients were recruited from December 2018 to December 2020: 97 patients received 1 g of ferric carboxymaltose (FCM) and 98 patients received 100 mL of physiological serum on postoperative day 1. Measurements: hemoglobin levels, reticulocyte count, serum iron, serum ferritin, and transferrin saturation were measured at induction of anesthesia, postoperative days 1, 5, and 30. Transfusion rate, duration of mechanical ventilation, critical care unit length of stay, and side effects associated with IV iron administration were measured. The primary outcome was hemoglobin level on day 30. Secondary outcomes included iron balance, transfused red cell packs, and critical care unit length of stay.

At day 30, the hemoglobine level was higher in the FCM group than in the placebo group (mean 12.9 ± 1.2 vs. 12.1 ± 1.3 g/dL (95%CI 0.41–1.23, p-value <0.001)). Patients in the FCM group received fewer blood units (median 1[0-2] unit vs. 2 [0-3] units, p-value = 0.037) and had significant improvement in iron balance compared to the control group. No side effects associated with FCM administration were reported.

In this randomized controlled trial, administration of FCM on postoperative day 1 in non-anemic patients undergoing cardiac surgery increased hemoglobin levels by 0.8 g/dL on postoperative day 30, leading to reduced transfusion rate, and improved iron levels on postoperative day 5 and 30.

NCT03759964.