Association of the triglyceride-glucose index and triglyceride-glucose-body mass index with postoperative atrial fibrillation in patients undergoing off-pump coronary artery bypass grafting: a retrospective cohort study

Background: Postoperative atrial fibrillation (POAF) is a common complication following off-pump coronary artery bypass grafting (OPCABG). Insulin resistance (IR) contributes to the pathogenesis of POAF. IR-related markers, including the triglyceride-glucose (TyG) index and the triglyceride-glucose-body mass index (TyG-BMI), have demonstrated prognostic value for cardiovascular events. However, their associations with POAF specifically after OPCABG remain unclear. This study aimed to evaluate the associations of TyG and TyG-BMI with POAF and their incremental value beyond conventional clinical risk factors. Methods: We conducted a single-center retrospective cohort study of adult patients who underwent isolated OPCABG between December 2020 and December 2021. Of 757 otherwise eligible patients, 93 without the preoperative fasting glucose and/or triglyceride measurements required to calculate the indices were excluded, leaving 664 participants in the primary analysis. Multivariable logistic regression, restricted cubic spline (RCS), discrimination and reclassification analyses, and bootstrap internal validation were performed. Results: Of the 664 participants, 180 (27.1%) developed POAF. In the fully adjusted model, each standard deviation increase in TyG and TyG-BMI was associated with higher odds of POAF [TyG: odds ratio (OR), 1.55; 95% confidence interval (CI): 1.28-1.89; TyG-BMI: OR, 1.60; 95% CI: 1.31-1.96; both P<0.001]. RCS analysis showed an approximately linear association for TyG (P for nonlinearity =0.16) and a nonlinear association for TyG-BMI (P for nonlinearity =0.02). Adding TyG or TyG-BMI to the baseline model increased the C-statistic from 0.682 to 0.708 or 0.707, respectively, although the changes were not statistically significant (P=0.07 and P=0.08). Both indices improved the integrated discrimination improvement (IDI) and continuous net reclassification improvement (NRI) (all P<0.001). Associations were stronger among patients with diabetes (P for interaction =0.02 for TyG and 0.005 for TyG-BMI). Conclusions: Higher preoperative TyG and TyG-BMI values were independently associated with POAF after OPCABG. These routinely available indices provided modest incremental risk information beyond conventional clinical risk factors. External validation is required before their use for clinical decision-making.