Incidence and healing times of postoperative sternal wound infections: a retrospective observational single-centre study

Objectives: Analyses of incidence and time required to heal sternal wound infections after heart surgery performed via a median sternotomy between 2020 and 2022. Results: Superficial wound infections (SWI) were five times more common (2.7%) than mediastinitis (0.5%) among 2693 patients. The median time between the operation and diagnosis of SWI was 26 (interquartile range [IQR] 15-33) days vs. 16 (IQR 9-25) days for mediastinitis (p = .12). Gram-negative bacteria caused 44% of the 85 infections. Sternal wound infection correlated to higher body mass index, female sex, smoking, diabetes mellitus, previous myocardial infarction, coronary artery bypass grafting, use of internal mammary graft, and re-entry for postoperative bleeding. Eight of 59 patients (13.6%) with sternal wound infections had bilateral mammary grafts, compared to 102 of 1191 patients (8.6%) without wound infections (p = .28). Negative pressure wound therapy was always used to treat mediastinitis and applied in 63% of patients with SWI. Two of 13 patients with mediastinitis (15%) and none of 72 patients with SWI died within 90 days after the operation. The median time until the wound healed was 1.9 (IQR 1.3-3.7) months after SWI vs. 1.7 (IQR 1.3-5.3) months after mediastinitis (p = .63). Six patients (7%) required longer than one year to treat the infection. Conclusions: Postoperative sternal wound infections usually appeared several weeks after surgery and were associated with factors as high body mass index, diabetes mellitus and coronary artery bypass. SWI were more common than mediastinitis and often required negative pressure wound therapy and similar treatment time as mediastinitis.