Preoperative iron status and its association with adverse outcomes in pediatric congenital heart disease

Iron imbalance, including iron deficiency and overload, is associated with increased cardiovascular morbidity and mortality. However, the iron status and its association with postoperative adverse outcomes in pediatric patients with congenital heart disease (CHD) is unclear. This study aimed to investigate the preoperative iron status and its correlation with adverse outcomes in pediatric patients with CHD.

This is a single-center retrospective study. A total of 8065 pediatric patients (aged 1 month to 5 years) who underwent surgical treatment at Fuwai Hospital's Pediatric Cardiac Surgery Center between 2017 and 2022 were consecutively included. All patients had undergone comprehensive preoperative laboratory tests, including iron-related hematology and biochemistry examinations. The association between ferritin and adverse outcomes was examined using restricted cubic splines. A multivariable logistic regression model was used to determine the associations between preoperative iron status and postoperative adverse outcomes.

Iron deficiency, anemia, and iron deficiency anemia were observed in 23.0% (1856/8065), 12.0% (969/8065), and 7.0% (564/8065) of patients, respectively. Patients with cyanotic CHD had a higher prevalence of iron deficiency but a lower incidence of anemia compared with patients with acyanotic CHD. A right-skewed U-shaped relationship was observed between ferritin and death and composite adverse events. Multivariable logistic regression analysis demonstrated that patients with high ferritin levels (ferritin ≥100 µg/L) had a significantly higher risk of in-hospital death (odds ratio [OR]: 8.20, 95% confidence interval [CI]: 1.61-41.86]) and composite adverse events (OR: 4.21 [95%CI: 2.65-6.68]) compared with patients with iron repletion (ferritin levels of ≥15 and <33 µg/L). In addition, patients with iron deficiency (OR: 1.80 [95%CI: 1.18-2.73]) and intermediate ferritin levels (ferritin levels of ≥33 and <100 µg/L; OR: 1.64 [95%CI: 1.11-2.44]) had a higher incidence of composite adverse events compared with those with iron repletion.

Iron deficiency and anemia are common concern in children with CHD. Preoperative iron imbalance, including both iron deficiency and high iron load, was significantly associated with postoperative adverse outcomes in pediatric patients with CHD. Assessment of preoperative iron status might facilitate early identification of high-risk patients, and correcting iron imbalance could potentially mitigate adverse outcomes.