The impact of preoperative latent iron deficiency on hospital outcomes in cardiac surgery patients

Introduction. Hypoferremia is an underrecognized clinical and laboratory syndrome. Its routine markers, ferritin and transferrin saturation (TSAT), are influenced by multiple factors and may not always provide an objective assessment of iron metabolism.

Aim: to evaluate the impact of preoperative hypoferremia on the development of adverse postoperative outcomes in patients undergoing elective cardiac surgery with cardiopulmonary bypass.

Materials and methods. This retrospective cohort study included 233 non-anemic patients (hemoglobin concentration >130 g/L) who underwent cardiac surgery. The isolated effects of ferritin and TSAT levels on postoperative outcomes were assessed. Subsequently, patients were stratified into four groups according to ferritin (<30 or ≥30 ng/mL) and TSAT (<20 % or ≥20 %) levels. The primary endpoints were mortality and a composite endpoint including mortality, acute coronary and cerebrovascular events, heart failure, renal failure, and respiratory failure. Secondary endpoints included the duration of mechanical ventilation (MV), length of stay in the intensive care unit (ICU), and total hospital stay.

Results. Isolated analysis of ferritin and TSAT revealed no significant association with the risk of adverse outcomes. Stratification demonstrated that patients with ferritin < 30 ng/mL and TSAT < 20 % had a significantly higher risk of acute kidney injury (AKI) compared with the reference group (p = 0.001). After merging groups II–IV (due to the absence of significant differences among them) and performing multivariate analysis, hypoferremia was found to be associated with an increased risk of CE (OR 3.317; 95 % CI 1.024–10.750; p = 0.045), acute heart failure (OR 4.784; 95 % CI 1.169–19.582; p = 0.030), AKI (OR 6.868; 95 % CI 1.550–30.460; p = 0.011), and red blood cell transfusion (OR 3.407; 95 % CI 1.002–11.579; p = 0.050). Hypoferremia was also associated with prolonged СMV duration and length of hospitalization.

Conclusion. Hypoferremia is associated with an increased risk of adverse hospital outcomes in patients undergoing cardiac surgery. These findings support the inclusion of iron status assessment in preoperative risk stratification and underscore the importance of early detection and correction of latent iron deficiency before surgery.

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