Perioperative Systemic Inflammatory Activation and Early Outcomes After Coronary Artery Bypass Grafting: A Retrospective Cohort Study

Background: Systemic inflammatory activation after coronary artery bypass grafting (CABG) is associated with postoperative complications. We investigated the association of perioperative inflammatory markers with an early composite postoperative adverse outcome and clinically indicated graft pathology after on-pump or off-pump CABG. Methods: This retrospective cohort study included 350 patients undergoing isolated CABG between January 2021 and December 2025; 250 underwent on-pump and 100 off-pump surgery. Demographic, laboratory, echocardiographic, surgical, and clinical data were collected. The neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, systemic immune-inflammatory index (SII), systemic inflammatory response index, C-reactive protein/albumin ratio, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) were assessed perioperatively. The primary endpoint was a composite early postoperative adverse outcome, defined as the occurrence of any of the following: in-hospital mortality, postoperative atrial fibrillation, acute kidney injury, low cardiac output syndrome, prolonged mechanical ventilation (>24 h), or intensive care unit stay exceeding 72 h. The graft pathology was assessed among patients undergoing clinically indicated postoperative coronary angiography. Results: Postoperative inflammatory activity was greater after on-pump CABG. At 24 h, the SII was higher in the on-pump group (1684 ± 542 vs. 1187 ± 436; p < 0.001), as were the IL-6 and TNF-α levels (both p < 0.001). The composite early postoperative adverse outcome occurred in 97 patients (27.7%). The postoperative SII, IL-6, TNF-α, and C-reactive protein/albumin ratio were higher in patients with the composite postoperative adverse outcome. Elevated postoperative SII (OR 1.84, 95% CI 1.29–2.63; p = 0.001) and IL-6 (OR 1.91, 95% CI 1.34–2.88; p < 0.001) independently was associated with MACE. Among 51 patients undergoing angiography, the graft pathology was identified in 17. Conclusions: Perioperative systemic immune-inflammatory activation is independently associated with early postoperative adverse outcomes after CABG. Postoperative SII and IL-6 may provide prognostic information for identifying patients at an increased risk of complications.