Abstract
BACKGROUND: Post-operative atrial fibrillation (POAF) prolongs recovery after cardiac surgery. We evaluated whether two myocardial-remodelling biomarkers-procollagen type I C-terminal propeptide (PICP) and procollagen type III N-terminal propeptide (PIIINP)-predict POAF in elderly patients. METHODS: In a prospective cohort (August 2024 - January 2025), 113 patients ≥ 65 years undergoing coronary artery bypass grafting, valve, or combined surgery were enrolled. Pre-operative serum PICP and PIIINP were quantified. POAF episodes were continuously monitored for five days. Independent predictors were identified with multivariable logistic regression, and discriminative performance was assessed using receiver-operating-characteristic (ROC) curves with 2,000-bootstrap internal validation. RESULTS: POAF developed in 40 patients (35.4%), peaking on post-operative day 2. Compared with non-POAF patients, the POAF group had larger left atria (45.3 ± 4.8 vs. 40.7 ± 5.1 mm; p < 0.001) and higher PICP (128.4 ± 27.1 vs. 103.2 ± 24.6 µg/L) and PIIINP (13.3 ± 3.9 vs. 9.8 ± 2.8 µg/L) concentrations (both p < 0.001). Age, left-atrial dimension, PICP, and PIIINP remained independent predictors (all p < 0.05). A model combining both biomarkers achieved an area under the ROC curve (AUC) of 0.86, outperforming PICP (0.80) or PIIINP (0.78) alone. Bootstrap validation yielded a mean AUC of 0.85 (95% CI 0.79-0.90), indicating good internal robustness. CONCLUSIONS: Elevated pre-operative PICP and PIIINP independently predict POAF in elderly cardiac-surgery patients, and their combination enhances risk stratification beyond clinical factors. Incorporating these biomarkers could guide targeted prophylaxis and improve peri-operative management; prospective multicentre validation is warranted.