Usefulness of the systemic immune inflammation index to predict atrial fibrillation recurrence after cryoablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter-based atrial fibrillation (AF) ablation is an effective and reliable therapy in the treatment of patients with symptomatic and drug-refractory atrial fibrillation [1, 2]. Several factors and noninvasive clinical markers have been investigated to predict the success rate of catheter ablation[3, 4]. Inflammation is a well-established risk factor in the pathogenesis, initiation and perputuation of AF and in the recurrence of AF following ablation procedures [ 5]. The systemic immune inflammation index (SII) has emerged as a new predictor of inflammation and is determined using the following equation: neutrophil (N) × platelet (P) ÷ lymphocyte (L)[6]. The predictive value of this index on routine blood tests have been examined and suggested to be a powerful and independent prognostic factor of several cardiovascular diseases. [7, 8]. The current study sought to assess whether there is a relationship between SII level and recurrence of AF after catheter ablation. Methods This study was a single center and non-randomized study conducted at our city hospital Department of Cardiology. From January 2019 to March 2021 a total of 370 consecutive patients with symptomatic AF who underwent cryoablation were enrolled. The study population consisted of patients (mean age 56.1±12.3 years, 50.5% male) with drug-resistant symptomatic AF who underwent initial PV isolation with cryoballoon technique for documented AF. The patients were divided into two groups according to receurrence development Results After a mean follow-up period of 25.0±6.7 months, early recurrence was developed in 36 (9.7%) patients and recurrence after blanking period was observed in 77 patients (20.8%) patients. According to multivariate Cox proportional hazard regression analysis, pre-ablation SII level (HR: 2.32, 95% CI: 1.35–3.98, P: 0.002), left ventricular ejection fraction (HR: 0.96, 95% CI: 0.93–0.99, P : 0.020) and EHRA Score (HR: 2.04, 95% CI: 1.34–3.10, P : 0.001) were independent predictors of AF recurrence after cryoablation. In ROC curve analysis, using a cut-off level of 532, the pre-ablation SII level predicted AF recurrence with a sensitivity of 71.4% and a specificity of 67.9% (AUC: 0.88, 95% CI: 0.67–0.80; P <0.001) (Figure 1). In addition, correlation analysis revealed that there was a positive correlation of pre-procedural SII level with pre-procedural hsCRP level (r: 0.340, P <0.001). Figure 2 represent the Kaplan–Meier curves for the freedom from AF recurrence according to SII cut-off level of 532 (log-rank, P < 0.001). Conclusions Our findings revealed that, in patients with paroxysmal and/or persistent AF undergoing cryoablation, increased pre-ablation SII levels were associated with a higher rate of AF recurrence. As a readily available, low-cost and easy to access marker of inflammation, pre-ablation SII level has well-predicted AF recurrence after cryoballoon-based ablation.