Pre-ablation Dual-Energy CT-derived Extracellular Volume Fraction Predicts Recurrence After Radiofrequency Ablation in Non-paroxysmal Atrial Fibrillation.

OBJECTIVES: To determine whether pre-ablation left ventricular extracellular volume fraction (ECV), derived from delayed-phase dual-energy cardiac computed tomography angiography (CTA), predicts atrial fibrillation (AF) recurrence after radiofrequency ablation in patients with non-paroxysmal AF. METHODS: In this retrospective cohort, 399 patients with non-paroxysmal AF undergoing radiofrequency ablation were included. All patients underwent preprocedural cardiac CTA with delayed-phase imaging acquired 5 minutes after contrast administration to quantify left ventricular ECV. To identify independent predictors of AF recurrence, patients were stratified by an optimal ROC-derived cutoff and analyzed using univariate and multivariate Cox proportional hazards models. Model performance was assessed using the concordance index (C-index), net reclassification index (NRI), and integrated discrimination improvement (IDI). RESULTS: During 10.1 months of follow-up (interquartile range, 8.1-13.6), 91 patients (22.8%) experienced AF recurrence after post-ablation. Recurrence was significantly associated with higher ECV values (37.6% ± 5.05% vs. 32.6% ± 2.05%; p < 0.01). The optimal ECV cutoff of 34.69% demonstrated an area under the curve (AUC) of 0.85 (95%CI: 0.79-0.90). Multivariate Cox regression identified high ECV (HR = 1.84; 95%CI: 1.24-2.33; p < 0.01) as independent predictors of AF recurrence. Additionally, integrating ECV with traditional clinical risk factors significantly enhanced predictive performance, achieving a C-index of 0.82 (95% CI: 0.74-0.86), an IDI of 0.66 (95%CI: 0.41-0.91), and an NRI of 0.55 (95%CI: 0.26-0.61). CONCLUSIONS: In non-paroxysmal AF patients, myocardial ECV derived from delayed-phase CT is an independent predictor of AF recurrence. ADVANCES IN KNOWLEDGE: This study provides evidence that DECT-derived ECV, a surrogate marker of diffuse myocardial fibrosis, can stratify recurrence risk in non-paroxysmal AF patients.