Association of Preoperative Platelet-Activating Factor and Postoperative C-Reactive Protein with Inflammatory Burden and Early Outcomes After Major Cardiac Surgery

Background: Major cardiac surgery with cardiopulmonary bypass (CPB) induces a systemic inflammatory response that contributes to postoperative organ dysfunction and hemodynamic instability. While C-reactive protein (CRP) is a well-established downstream marker of postoperative inflammation, the upstream determinants of interindividual variability in inflammatory burden are not fully understood. Platelet-activating factor (PAF) is a potent inflammatory mediator implicated in platelet activation, endothelial dysfunction, and vascular dysregulation, but its role in modulating postoperative inflammation and clinical outcomes after cardiac surgery has not been fully characterized. Methods: We conducted a retrospective observational study of 87 patients undergoing major cardiac surgery with CPB. Preoperative plasma PAF levels and postoperative CRP concentrations were measured, and patients were stratified according to postoperative CRP severity. Associations between PAF, inflammatory response, postoperative vasoactive–inotropic requirements, recovery parameters, acute kidney injury, and mortality were assessed using correlation analyses, multivariable regression models, and receiver operating characteristic curve analyses. Results: Preoperative PAF levels increased progressively across postoperative CRP strata (p < 0.001) and were strongly associated with postoperative CRP concentrations in both univariate and multivariable analyses. Specifically, each 1000 pg/mL increase in preoperative PAF was associated with an adjusted increase of 36.0 mg/L in postoperative CRP (β = 36.0; p < 0.001). Each 1000 pg/mL increase in preoperative PAF was associated with an adjusted increase of approximately 36 mg/L in postoperative CRP. Elevated PAF was also associated with increased intermediate postoperative vasoactive–inotropic requirements and a modest increase in hospital length of stay (r = 0.25, p = 0.023). However, neither PAF nor CRP independently predicted AKI or mortality after adjustment for clinical variables. Discriminative performance for mortality was modest for both biomarkers. Conclusions: Preoperative platelet-activating factor was strongly associated with postoperative inflammatory burden and early hemodynamic instability following major cardiac surgery. Although PAF and CRP were not independent predictors of adverse outcomes, they may help identify a biologically vulnerable phenotype characterized by exaggerated inflammatory and vascular responses to surgical stress. These findings support further investigation of platelet-mediated inflammatory pathways as targets for perioperative risk stratification and mechanistic research.