Sex specific differences in outcomes following atrial fibrillation (AF) ablation versus medical therapy in patients with AF and heart failure

All participants will undergo a 5-week period of medical optimisation as part of standard care. The 5 week medical optimisation includes ensuring adequate AF rate control using medical therapy (rate control medications) and optimising heart failure therapy and fluid status (i.e. using diuretics for fluid overload, ensuring guideline-directed therapies for heart failure are incorporated as tolerated). Medical optimisation within the study protocol does not differ from routine AF and heart failure management. Management during this medical optimisation period follows routine clinical practice and does not differ from usual care. AF catheter ablation (AF ablation) Catheter ablation will be performed by a specialist Cardiac electrophysiologist using a standard ablation approach (this includes radiofrequency, cryoablation or pulsed field ablation, depending on local institutional practice) for atrial fibrillation. Following trans-septal access to the left atrium, electroanatomical mapping will be undertaken using a three-dimensional mapping system. Pulmonary vein isolation (PVI) will be performed, with delivery of ablation lesions to achieve electrical isolation of all pulmonary veins. Additional ablation (e.g. targeting non-pulmonary vein triggers or substrate modification) may be performed at the discretion of the treating operator in accordance with standard clinical practice. The procedure will be performed by a cardiac electrophysiologist (a cardiologist with specialist training in cardiac rhythm disorders and catheter ablation) in an accredited electrophysiology laboratory. The approximate procedure duration will be between 1-3 hours per participant, depending on institutional practice and ablation technology utilized. If allocated to ablation, the intervention (ablation) will be delivered as a single procedure during the the study period. Repeat ablation procedures may be performed if clinically indicated during follow-up, according to standard care. The procedure will be conducted in a hospital-based electrophysiology laboratory within participating tertiary referral centres.