Characterization of Postoperative Infection Risk in Cardiac Surgery Patients With Delayed Sternal Closure

Objectives: To compare the incidence of postoperative infection in cardiac surgery patients who had delayed sternal closure (DSC) with those who had primary sternal closure (PSC) and evaluate the effectiveness of antibiotic prophylaxis in DSC patients. Design: Retrospective, observational cohort study with propensity score matching. Setting: Single academic medical center. Participants: Cardiothoracic surgery patients, excluding transplantation patients, from a single academic medical center who had DSC or PSC between November 2015 and November 2018. Interventions: None. Measurements and Main Results: Of 2,685 patients who had cardiac surgery with cardiopulmonary bypass, 99 had DSC. Fifty-nine DSC patients met study inclusion criteria, and the final propensity score matched cohort included 57 patients with DSC and 57 patients with PSC. Propensity score matching reduced bias but was unable to balance all covariates. The most common indication for DSC was coagulopathy in 32 of the 57 patients. All patients in the PSC group received routine antibiotic prophylaxis for 48 hours after surgery. Patients in the DSC group received prolonged broadened prophylaxis until 48 hours after sternal closure. Despite prolonged broadened antibiotic prophylaxis, the DSC group had a higher rate of postoperative infection (31.6% v 3.5%; p < 0.005), mainly pneumonia (19.3% v 1.8%; p < 0.005), in the first 30 days after surgery. There was no difference in the incidence of sepsis (5.3% v 0%; p = 0.24), superficial skin and soft tissue infection (1.8% v 1.8%; p = 1), or mediastinitis/deep tissue infection (5.3% v 0%; p = 0.24) in patients with DSC. Seventy-seven percent of causative organisms for infection were Gram-negative bacteria in the matched cohort. Conclusion: The incidence of postoperative infection, particularly pneumonia, is high in cardiothoracic surgery patients with DSC, even with prolonged broadened antibiotic prophylaxis, but the rate of mediastinitis/deep tissue infection did not appear to be greater with DSC. Additional research is needed into optimal antibiotic prophylaxis in this high-risk group of patients. (C) 2020 Elsevier Inc. All rights reserved.