Objective To investigate the relationship between nuclear mitotic protein 22 (NMP22) combined with platelet function test and postoperative atrial fibrillation (POAF) occurrence in middle-aged and elderly patients with coronary heart disease undergoing coronary artery bypass grafting (CABG).

Methods Patients scheduled for CABG surgery for the first time and aged 50 years or older were selected as the study subjects. Preoperative, intraoperative, and postoperative data were collected. Urine samples were obtained at 24 hours before CABG, 6, 12, and 18 hours after surgery, and the concentration of NMP22 was measured using standard ELISA. Multivariate logistic regression analysis was employed to identify predictors of POAF and construct a prediction model. The ROC curve was used to assess the discriminatory ability of the predictive model, while the net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were utilized to evaluate the improvement of the prediction model after incorporating NMP22.

Results A total of 151 patients were ultimately included, of which 43 cases developed POAF, with an incidence rate of 28.5%. Compared with the non-POAF group, patients in the POAF group had higher age, left atrial diameter, right atrial diameter, preoperative platelet count, preoperative use of calcium channel blockers, number of grafts, intraoperative use of intra-aortic balloon pump, platelet count, serum creatinine, serum urea nitrogen levels at 12 hours after surgery, and NMP22 levels at 6 and 12 hours after surgery (P ＜ 0.05 to P ＜ 0.01). Multivariate logistic regression analysis showed that old age, increased left atrial diameter, increased right atrial diameter, number of grafts, elevated platelet count at 12 hours after surgery, and elevated NMP22 levels at 12 hours after surgery were independent risk factors for POAF (P ＜ 0.05 to P ＜ 0.01). Based on these six variables, a POAF prediction model was constructed. ROC curve analysis showed that the AUC of the model predicting POAF was 0.871 (95% CI: 0.825–0.917), with a sensitivity of 79.8% and a specificity of 88.7%. Based on the gradual increase in the prevalence of POAF in the overall risk score, patients were divided into three risk groups: low-risk (0–3 points), moderate risk (4–6 points), and high-risk (7–9 points). The prevalence of POAF was 9.8% (6/61), 28.3% (15/53), and 59.5% (22/37), respectively (χ² = 27.86, P ＜ 0.01).

Conclusions A prediction model for POAF was established based on age, left atrial diameter, right atrial diameter, number of grafts, platelet count at 12 hours after surgery, and NMP22 levels at 12 hours after surgery, which performed well in predicting POAF in patients undergoing CABG surgery. The inclusion of NMP22 helps to divide CABG patients into three POAF risk groups for different prevention strategies.