Background: Atrial fibrillation (AF) recurrence following catheter ablation remains high. Recent studies have shown a relation between epicardial adipose tissue and AF. epicardial adipose tissue secretes several proinflammatory and anti-inflammatory adipokines that directly interact with the adjacent myocardium. The aim of the current study was to evaluate whether posterior left atrial (LA) adipose tissue attenuation, as marker of inflammation, is related to AF recurrences after catheter ablation. Methods: Consecutive patients with symptomatic AF referred for first AF catheter ablation who underwent computed tomography were included. The total epicardial adipose tissue and posterior LA adipose tissue were manually traced and adipose tissue was automatically recognized as tissue with Hounsfield units (HU) between −195 and −45. The attenuation value of the posterior LA adipose tissue was assessed, and the population was divided according to the mean HU value (−96.4 HU). Results: In total, 460 patients (66% male, age 61±10 years) were included in the analysis. After a median follow-up of 18 months (interquartile range, 6–32), 168 (37%) patients had AF recurrence. Patients with higher attenuation (≥−96.4 HU) of the posterior LA adipose tissue showed higher AF recurrence rates compared with patients with lower attenuation (<−96.4 HU; log-rank test P =0.046). Univariate analysis showed an association between AF recurrence and higher posterior LA adipose tissue attenuation (≥−96.4 HU; P <0.05). On multivariable analysis, posterior LA adipose tissue attenuation (hazard ratio, 1.26 [95% CI, 0.90–1.76]; P =0.181) remained a promising predictor of AF recurrence following catheter ablation. Conclusions: Posterior LA adipose tissue attenuation is a promising predictor of AF recurrence in patients who undergo catheter ablation. Higher adipose tissue attenuation might signal increased local inflammation and serve as an imaging biomarker of increased risk of AF recurrence. Graphic Abstract: A graphic abstract is available for this article.