Mediastinitis is a severe complication of heart surgery well described in the adult population. However very few studies focused on the description of mediastinitis and its outcomes in pediatric patients.

To describe the clinical features and outcomes of postoperative mediastinitis in children and identify risk factors for mortality.

We retrospectively reviewed all children with mediastinitis over a period of 10 years (2013–2023). Mediastinitis was defined by a purulent discharge of the mediastinum requiring surgery or organisms cultured from discharge of the mediastinal area.

The incidence of mediastinitis was 0.74% (57 cases). Median age at surgery was 12 days with 67% patients younger than 3 months old. Sixty percent had delayed sternal closure. Median delay between surgery and diagnosis was 8 days (range: 2–39). The most frequent germs were Staphylococcus (46%), gram negative bacteria (35%) and fungi (9%). All patients had surgical debridement: 46 (81%) in the operating room and 11 (19%) in the ICU. Median duration of antibiotic therapy was 44 days. Median duration of stay was 21 days (range: 10–113) in the ICU and 35 days (range: 11–188) until hospital discharge. Outcomes in the ICU included a median of 8 days of assisted ventilation. Nine patients needed veno-arterial ECMO. Mortality rate was 27% with 12 out of 15 deaths occurring in the ICU. Mortality risk factors were surgical revision in the ICU compared to the operating room (OR 4.9; CI95% 1.3 to 19.9), delayed sternal closure superior to 3 days (OR: 5.0; 95% CI: 1.3 to 16.5) and fungal mediastinitis (OR: 14.9; 95% CI: 2.0 to 185.4).

Mediastinitis leads to high mortality and morbidity in children. Mortality risk factors are: surgical revision in the ICU, prolonged delayed sternal closure and fungus infection. Patients with prolonged delayed sternal closure should be regularly screened for fungal colonization to prevent fungal mediastinitis.