Deep sternal wound infection after cardiac surgery: A combination of 2 distinct infection types, deep incisional surgical-site infection and mediastinitis: Results of a retrospective study

Deep sternal wound infection after cardiac surgery remains a serious complication associated with a poor prognosis. Deep sternal wound infection is classified by the Centers for Disease Control and Prevention as deep incisional surgical site-infection and mediastinitis. This study aims to describe the incidence, perioperative characteristics, and outcomes of deep sternal wound infection on the basis of clinical presentations. This monocentric retrospective study included all consecutive patients who underwent cardiac surgery with cardiopulmonary bypass between 2006 and 2019 in a tertiary teaching hospital. The primary outcome was 90-day mortality, and the main secondary outcome was a landmark analysis of 90-day mortality, excluding patients who died within the first 28 days. Among the 14,850 patients included in this study, deep sternal wound infection occurred in 542 (3.6%) patients: 390 (72%) presented with deep incisional surgical site-infection and 152 (28%) presented mediastinitis. Patients with deep sternal wound infection had a lower 90-day survival than patients without deep sternal wound infection; in particular, patients with mediastinitis had the lowest survival rate compared to deep incisional surgical site-infection- and deep sternal wound infection -free patients (82% vs 94% vs 95%, respectively; both comparisons P < .001), and mediastinitis was an independent risk factor for 90-day mortality. No difference in 90-day survival was observed between patients without deep sternal wound infection and patients with deep incisional surgical site-infection (P = .378). However, in the landmark analysis, both deep incisional surgical site-infection and mediastinitis were associated with lower survival compared with patients without deep sternal wound infection and were independent risk factors for mortality. Deep incisional surgical site-infection and mediastinitis exhibited distinct incidences, bacterial characteristics, and prognoses, with mediastinitis being associated with the poorest prognosis. However, when the competing risk of death was considered, deep incisional surgical-site infection diSSI also emerged as an independent risk factor for 90-day mortality.