Left atrial Soluble ST2 and BNP response after pulmonary vein isolation as a predictor of atrial fibrillation recurrence

Background Atrial fibrillation (AF) recurrence after ablation remains a common clinical challenge despite effective pulmonary vein isolation (PVI). AF recurrence arises from complex pathophysiological mechanisms including inflammation, oxidative stress, and fibrotic remodeling that progressively alter the atrial substrate [1, 2]. The local tissue response following ablation, involving acute myocardial injury and subsequent healing, may represent one of the mechanisms that sustain arrhythmogenic remodeling and predispose to recurrence [3]. Among several candidate biomarkers, soluble suppression of tumorigenicity-2 (sST2) has gained attention as a dynamic marker of myocardial stress, inflammation, and fibrosis [4]. Evaluating such localized biochemical responses may improve understanding of post-procedural atrial remodeling and aid in identifying patients at higher risk of AF recurrence. Objective To investigate whether biochemical changes observed in locally obtained left atrial blood samples before and after pulmonary vein isolation are associated with AF recurrence during six-month follow-up after ablation. Methods Among 133 patients who underwent AF ablation, 88 paroxysmal AF patients treated with either radiofrequency or cryoballoon PVI were included. Patients with persistent AF, additional ablation lines, incomplete pulmonary vein isolation, inadequate left atrial sampling, or incomplete follow-up were excluded. Left atrial blood samples were collected before and after ablation, centrifuged, and stored at −80°C. Soluble ST2 (sST2) was measured using ELISA, while BNP and troponin were assessed by standard laboratory assays. AF recurrence was defined as documented atrial fibrillation on ECG or Holter monitoring within 3, 6 months of follow-up. Results Baseline characteristics of the study population are summarized in (Table 1). AF recurrence occurred in 9 patients (10.2%). LA diameter was significantly greater in patients with recurrence (43.3 ± 3.0 vs. 40.3 ± 4.3 mm, p=0.044). Post-procedural BNP (273.5 ± 111.6 vs. 150.1 ± 130.0 pg/mL, p=0.009) and sST2 levels (45.0 ± 13.9 vs. 22.8 ± 18.3 pg/mL, p<0.001) were markedly higher, while troponin also showed a non-significant upward trend (160 ± 64.8 vs. 117.7 ± 90.1 ng/L, p=0.177). In multivariate analysis, LA diameter (OR 1.54, 95% CI 1.15–2.07, p=0.004), BNP ratio (OR 4.12, 95% CI 1.15–14.23, p=0.003), and sST2 ratio (OR 3.13, 95% CI 1.07–9.11, p=0.037) were independent predictors of AF recurrence. (Table 2) Conclusion An increase in locally measured soluble ST2 and BNP following PVI independently predicts AF recurrence. This elevation suggests that post-ablation atrial stress and fibrotic response contribute to both early and later recurrences.Table 1,2Fıgure 1