biostudies-literatureLuo LBeijing Municipal Natural Science FoundationCapital Medical University Innovation ProjectNational Natural Science Foundation of China2862https://www.ebi.ac.uk/biostudies/studies/S-EPMC12828024biostudies-literatureUnknown16(1)Myeloperoxidase (MPO) is associated with conduction inhomogeneity. We hypothesized that MPO in selectively drained pericardial fluid (PCF), a direct window into the cardiac microenvironment, may improve postoperative atrial fibrillation (POAF) risk prediction beyond existing risk scores. A total of 469 consecutive patients undergoing coronary artery bypass grafting (CABG) were enrolled in this study (n = 201 in derivation cohort and n = 268 in validation cohort). The primary outcome was new-onset POAF within the first 7 days postoperatively. MPO concentrations were measured in selectively drained PCF and peripheral blood at baseline, 0 and 6 h postoperatively. We further compared MPO levels between pure pericardial fluid and mixed drainage fluid (via Y-connector). A new prediction model, the pcMPO-AF rule, was developed using multivariable logistic regression and validated internally using bootstrapping and externally in an independent cohort. Approximately 98.0% of patients underwent off-pump CABG. POAF occurred in 31.8% and 35.1% of the derivation and validation cohorts, respectively. Pericardial MPO at 6 h postoperatively emerged as the strongest independent predictor of POAF. MPO concentrations in selectively drained PCF were 25-fold higher than mixed drainage samples and 1,648-fold higher than serum levels (both P < 0.001). The pcMPO-AF rule demonstrated good discrimination, with AUCs of 0.908 in derivation and 0.865 in validation cohorts, outperforming POAF, CHA₂DS₂-VASc, and HATCH scores. MPO in selectively drained PCF is a potent biomarker of POAF. The pcMPO-AF rule integrated PCF biomarkers with clinical factors, providing superior predictive performance by capturing both the vulnerable atrial substrate and acute inflammatory trigger.Scientific reportsThe pcMPO-AF rule for predicting postoperative atrial fibrillation after coronary artery bypass grafting.PMC1282802482200351, Y.L.7252277, Y.L.XSKY2024147, Y.L.Yang HLiu YPeng TLuo LWang TZhou WShu YGao CfalseThe pcMPO-AF rule for predicting postoperative atrial fibrillation after coronary artery bypass grafting.Myeloperoxidase (MPO) is associated with conduction inhomogeneity. We hypothesized that MPO in selectively drained pericardial fluid (PCF), a direct window into the cardiac microenvironment, may improve postoperative atrial fibrillation (POAF) risk prediction beyond existing risk scores. A total of 469 consecutive patients undergoing coronary artery bypass grafting (CABG) were enrolled in this study (n = 201 in derivation cohort and n = 268 in validation cohort). The primary outcome was new-onset POAF within the first 7 days postoperatively. MPO concentrations were measured in selectively drained PCF and peripheral blood at baseline, 0 and 6 h postoperatively. We further compared MPO levels between pure pericardial fluid and mixed drainage fluid (via Y-connector). A new prediction model, the pcMPO-AF rule, was developed using multivariable logistic regression and validated internally using bootstrapping and externally in an independent cohort. Approximately 98.0% of patients underwent off-pump CABG. POAF occurred in 31.8% and 35.1% of the derivation and validation cohorts, respectively. Pericardial MPO at 6 h postoperatively emerged as the strongest independent predictor of POAF. MPO concentrations in selectively drained PCF were 25-fold higher than mixed drainage samples and 1,648-fold higher than serum levels (both P < 0.001). The pcMPO-AF rule demonstrated good discrimination, with AUCs of 0.908 in derivation and 0.865 in validation cohorts, outperforming POAF, CHA₂DS₂-VASc, and HATCH scores. MPO in selectively drained PCF is a potent biomarker of POAF. The pcMPO-AF rule integrated PCF biomarkers with clinical factors, providing superior predictive performance by capturing both the vulnerable atrial substrate and acute inflammatory trigger.2026-01-01T00:00:00Z2026 Jan2026-06-06T21:47:17.931Z2026-06-05T03:11:56.852ZS-EPMC128280244156572210.1038/s41598-025-32318-x