Association between insulin resistance–related indices and the risk of recurrence after catheter ablation in patients with nonvalvular atrial fibrillation

Insulin resistance (IR) is closely associated with the development and recurrence of atrial fibrillation (AF). Several non-insulin-based surrogate markers of insulin resistance, including the triglyceride-glucose index (TyG), triglyceride-glucose-body mass index (TyG-BMI), metabolic score for insulin resistance (METS-IR), triglyceride-to-high-density lipoprotein cholesterol ratio (TG/HDL-C), estimated glucose disposal rate (eGDR), and C-reactive protein-triglyceride-glucose index (CTI), can be calculated from routine clinical biomarkers. However, the value of these indices in predicting recurrence after catheter ablation for AF remains unclear. In particular, CTI, a novel marker integrating inflammatory and metabolic status, has not been fully explored for its potential role in predicting post-ablation AF recurrence. This study aimed to systematically evaluate the association and predictive performance of six insulin resistance surrogate markers for AF recurrence after catheter ablation. This retrospective two-center cohort study included 590 patients with nonvalvular AF who underwent first-time catheter ablation between January 2022 and March 2025. Six IR surrogate indices were calculated, and AF recurrence within 1 year was defined as the primary endpoint. Multivariable Cox regression, Kaplan-Meier analysis, restricted cubic spline (RCS) analysis, C-statistic, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were used to assess associations and predictive value. During 1-year follow-up, 167 patients experienced recurrence (28.31%). Multivariable Cox analysis showed that lower eGDR and higher TyG, TyG-BMI, METS-IR, and CTI were associated with increased recurrence risk, with more stable associations observed for eGDR, TyG-BMI, METS-IR, and CTI. Kaplan-Meier and RCS analyses further supported stratified differences and exposure-response relationships for some indices. For predictive performance, eGDR showed the most favorable overall performance, while CTI, TyG-BMI, and METS-IR also provided incremental predictive value. TyG and TG/HDL-C showed relatively limited incremental value. After false discovery rate correction, subgroup analyses showed generally consistent results. Among the six IR surrogate indices, eGDR, CTI, TyG-BMI, and METS-IR were associated with AF recurrence after catheter ablation. eGDR showed the most favorable overall predictive performance. These indices may serve as adjunctive markers for post-ablation recurrence risk stratification, although prospective validation is needed.