Iron Deficiency and Hematological Changes in Adult Patients After Fontan Operation

Background: Growing evidence indicates that iron-deficiency anemia is common in patients with congenital heart diseases. The aim of this study was to characterize hematologic changes and iron metabolism in adult Fontan patients. We also searched for the associations between these parameters and physical performance in the study group.

Methods And Results: Thirty-two white Fontan patients with a mean age of 25 ± 4.5 years and 30 healthy control subjects matched for age and sex were studied. Complete blood count together with iron-related parameters was determined in plasma of peripheral venous blood. The cardiopulmonary exercise test was performed. The Fontan patients had higher red blood cell counts (6.0 ± 2.1 × 10(9)/μl vs. 4.8 ± 0.4 × 10(9)/μl, p<0.001), hemoglobin (16.7 ± 1.4 g/dl vs. 14.2 ± 1.3g/dl, p<0.001), hematocrit (49 ± 3.4% vs. 42.1 ± 3.1%, p<0.001), red cell distribution width (RDW) (14.3 ± 2.4% vs. 12.8 ± 0.5%, p<0.001), while mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were similar in both the groups. Compared to the controls, the Fontan patients had higher unsaturated iron binding capacity (46.1 ± 12.6 μmol/l vs. 38.4 ± 11.9 μmol/l, p=0.02), total iron-binding capacity (62.8 ± 9.8 μmol/l vs. 57.8 ± 8.5 μmol/l, p=0.04), lower transferrin saturation (27.4 ± 11.4% vs. 34.6 ± 13.4%, p=0.03), and oxygen uptake, while iron and ferritin levels were comparable in both the groups. The multivariate model showed that SatO2 and cystatin C were independent predictors of RDW, and alanine aminotransferase was an independent predictor of ferritin level. Interestingly RDW was an independent predictor of oxygen uptake.

Conclusion: Adult patients after Fontan operation despite having increased hemoglobin, hematocrit, and red blood cells have insufficient iron stores. Red cell distribution width is an indicator of iron deficiency in adult Fontan patients and it correlates with lower exercise capacity. Elevated ferritin levels in adult patients after Fontan surgery are associated with liver failure.