Predictive value of TGF-β1 for new-onset atrial fibrillation following coronary artery bypass grafting

Background Postoperative atrial fibrillation (POAF) is a severe complication after CABG, lacking precise predictors. Since TGF-β1 is critical for post-surgical collagen synthesis and metabolism, we investigated whether pericardial TGF-β1 levels within 18 hours post-CABG can accurately predict new-onset POAF. We hypothesized that localized inflammatory and fibrotic responses in the heart are more accurately reflected in pericardial fluid than in peripheral blood. Therefore, this study aimed to investigate whether dynamic TGF-β1 levels in pericardial drainage fluid within 18 hours post-surgery can serve as a highly accurate predictor for new-onset POAF. Method This prospective study enrolled patients undergoing elective off-pump CABG at a Hospital (2024-2025). POAF was monitored via Holter. Blood and pericardial fluid were collected up to 18 hours postoperatively, with TGF-β1 quantified by ELISA. Dynamic trajectories were evaluated using linear mixed-effects models. We assessed the predictive value of pericardial TGF-β1 and its incremental benefit over a baseline clinical model, validating a novel integrated model using decision curve analysis (DCA). Results Among 175 exploratory cohort patients, 61 (34.8%) developed POAF. Linear mixed-effects models showed a significant group-by-time interaction for pericardial, but not plasma, TGF-β1 (P=0.04), indicating a localized dynamic trajectory. At 12 hours post-op, each 1 ng/mL increase in pericardial TGF-β1 elevated POAF risk by 6% (OR=1.06, P<0.001). LASSO regression identified a clinical model (age, LAD, IVSM, BNP; AUC=0.767). Pericardial TGF-β1's predictive value peaked at 12 hours (AUC=0.773), outperforming intraoperative and 6-hour levels. Incorporating 12-hour pericardial TGF-β1 into the clinical model significantly improved the C-statistic to 0.810 (Δ C-statistic=0.043, P=0.029). The integrated model achieved a bootstrap-corrected AUC of 0.787 and a validation cohort AUC of 0.789. Conclusion Pericardial TGF-β1 reflects localized profibrotic changes preceding POAF better than systemic plasma levels. The 12-hour post-CABG mark emerges as the optimal monitoring window. Integrating this 12-hour biomarker with routine clinical parameters significantly enhances early POAF risk stratification, providing a validated tool for timely prophylactic intervention.