Retrospective evaluation of the relationship between catheter ablation and systemic immune-inflammation index in cardiac arrhythmias.

BACKGROUND: Catheter ablation induces controlled myocardial injury and transient endothelial dysfunction, both of which may trigger a systemic inflammatory response. The systemic immune-inflammation index (SII) has emerged as a sensitive biomarker reflecting the interplay between inflammation, thrombosis, and immune regulation; however, its peri-procedural behavior after ablation remains unclear. OBJECTIVE: To evaluate changes in SII following catheter ablation across different arrhythmia subtypes and to determine independent predictors of ΔSII. METHODS: In this retrospective cohort study, 642 adult patients who underwent catheter ablation between January 2022 and December 2024 were analyzed. Pre-procedural and 1-week post-procedural SII values were compared across diagnostic EPS (non-ablation reference group, n = 93), supraventricular tachycardia (SVT(AVNRT+AVRT), n = 384), atrial fibrillation (AF; RF n = 42 and cryoablation n = 51), atrial tachycardia (AT, n = 37), atrial flutter (AFL, n = 27), and ventricular ectopy (VES, n = 72) groups. Multivariable linear regression assessed predictors of ΔSII. Effect sizes were calculated using Cohen’s d and Hedges’ g. RESULTS: Overall SII increased significantly after ablation (p = 0.001). AF groups demonstrated the strongest effect sizes (RF-AF: d = 0.84; Cryo-AF: d = 1.07). No significant changes were observed after diagnostic EPS or AFL ablation. Regression analysis identified EF (β = − 19.4; p = 0.045), RF-AF (β = 808; p = 0.0016), Cryo-AF (β = 710; p < 0.001), and VES ablation (β = 471; p = 0.036) as independent predictors of ΔSII. CONCLUSION: Catheter ablation—particularly AF and VES ablation—is associated with significant early SII elevation, independent of conventional inflammatory markers such as CRP. These findings suggest that SII may reflect procedure-related inflammatory burden; however, its prognostic value and clinical utility require validation in prospective outcome-driven studies.