Impact of obesity on clinical outcomes and the treatment effect of catheter ablation in atrial fibrillation: insights from CABANA

Aims Obesity and atrial fibrillation (AF) are global epidemics, often co-existing and compounding cardiovascular risk. While catheter ablation has emerged as an effective strategy for rhythm control in symptomatic AF, it remains unclear whether obesity modifies its benefit. This post hoc analysis of the CABANA trial investigates the influence of baseline obesity on clinical outcomes after catheter ablation vs. drug therapy in AF patients. Methods and results A total of 2170 CABANA participants with available body mass index (BMI) were included. Obesity was defined by BMI ≥ 30 kg/m2, and Class II obesity by BMI ≥ 35 kg/m2. Adverse outcomes, AF recurrence, and functional status were analysed using Cox, mixed-effects, and generalized estimating equation models, assessing treatment-by-obesity interactions. Obese patients exhibited higher comorbidity burden, worse baseline functional status, and more persistent AF compared to non-obese counterparts. Higher BMI was associated with increased cardiovascular hospitalization and a higher New York Heart Association functional class. Catheter ablation significantly reduced the risk of AF recurrence and improved symptom burden and functional capacity, irrespective of obesity status. No significant interaction was found between BMI and treatment effect on the primary composite endpoint of cardiovascular hospitalization or all-cause mortality. However, patients with Class II obesity or higher had worse absolute outcomes despite similar relative benefits from ablation. Conclusion While obesity is associated with worse baseline status and outcomes, it was not shown to significantly alter the relative effectiveness of AF ablation compared to drug therapy. These findings support a multifaceted approach integrating rhythm control with upstream interventions targeting obesity-related atrial remodelling and comorbidity management.