Suspicious CT Findings Suggesting Mediastinitis or Sternal Osteomyelitis in Clinically Uninfected Patients After Cardiac Surgery: A 10-Year Single-Center Retrospective Study

Background/Objectives: Post-sternotomy mediastinitis and sternal osteomyelitis are serious complications of cardiac surgery associated with substantial morbidity and mortality. Computed tomography (CT) is widely used to evaluate suspected infection, but the frequency with which CT reports suggest infection in clinically uninfected post-sternotomy patients is poorly characterized. Methods: A retrospective observational study was conducted at a tertiary cardiac surgery center. Using an institutional data warehouse, all adult patients undergoing cardiac surgery via median sternotomy between 2010 and 2020 were identified. Patients with documented mediastinitis, sternal osteomyelitis, other postoperative infections, antibiotic treatment, or infectious disease consultation were excluded, as were patients without postoperative CT, those with coronary CT angiography only, and those whose CT scans were performed within 14 days or more than 1 year after surgery. CT reports of the remaining clinically uninfected patients were reviewed and categorized as either showing no evidence of mediastinitis/sternal osteomyelitis or containing findings interpreted as suspicious for these complications. Results: Among 4019 patients who underwent cardiac surgery during the study period, 92 highly selected clinically uninfected adults met the inclusion criteria and had eligible postoperative CT scans. Of these, 60 had coronary artery bypass grafting, 6 had mitral valve replacement, 17 had aortic valve replacement, and 9 had ascending aortic replacement. Four patients (4.4%; 95% CI, 1.2–10.9%) had CT reports describing findings suggestive of mediastinitis and/or sternal osteomyelitis despite the absence of concomitant clinical or laboratory evidence of infection. All four were post-coronary artery bypass grafting patients and had common radiologic features reported in postoperative infection, including sternal edge irregularity/erosion, sclerosis, retrosternal fluid collections, and mediastinal or presternal fat stranding. Conclusions: In this single-center retrospective series, CT reports suggesting mediastinitis or sternal osteomyelitis were observed in a small proportion of carefully selected, clinically uninfected post-sternotomy patients. These findings support the need to interpret CT abnormalities after cardiac surgery in close conjunction with clinical and laboratory data to avoid unnecessary invasive interventions in patients without true infection.