Differential Impact of Body Mass Index on Recurrence, Cardiac Remodelling, and Quality of Life After Atrial Fibrillation Ablation: Insights From the China‐ <scp>AF</scp> Registry

ABSTRACT Background The impact of body mass index (BMI) on the outcomes of radiofrequency catheter ablation (RFCA), including atrial fibrillation (AF) recurrence rate, cardiac remodelling, and quality of life (QoL), remains uncertain. Methods We analysed 12 104 first‐time RFCA patients from the China‐AF registry, stratified by BMI: under/normal weight (< 25 kg/m 2 ), overweight (25–29.9 kg/m 2 ), and obese (≥ 30 kg/m 2 ). The primary outcome was AF recurrence. Exploratory outcomes included 12‐month echocardiographic parameters and Atrial Fibrillation Effect on Quality‐of‐Life (AFEQT) scores. Multivariable Cox regression, median regression, restricted cubic splines (RCS), and subgroup analyses were performed. Results In this cohort (median age 61.55 years, 32.6% female), obese patients were significantly younger with higher comorbidities burdens. Over a median follow‐up of 47.5 months, 4932 (40.8%) patients experienced AF recurrence. BMI exhibited a linear, dose‐dependent association with recurrence risk (fully adjusted HR 1.01, 95% CI, 1.00–1.02; obese HR 1.16, 95% CI: 1.05–1.28), consistent across primary analyses, sensitivity analyses using Chinese BMI classification standards, and subgroups (with stronger associations in males, < 65 years, persistent AF), without significant interactions across these subgroups (all p interaction > 0.05). Exploratory analyses suggested obesity was linked to nonlinearly higher 12‐month left ventricular end‐diastolic diameter (LVEDD; 2.17 mm, 95% CI: 0.79–3.55) and left ventricular wall thickness (LVWT; 0.81 mm, 95% CI: 0.45–1.17) versus under/normal‐weight, with nonlinear association in primary analysis (both p nonlinear < 0.05). Conclusion Higher BMI exhibits a linear association with AF recurrence post‐RFCA. Obesity is linked to nonlinear adverse remodelling (LVEDD and LVWT).