Abstract Introduction Atrial fibrillation (AF) patients with heart failure (HF) face increased risks of AF recurrence and HF admission. Catheter ablation (CA) is a recognized treatment option. Due to observed atrial remodelling and fibrosis associated with ventricular remodelling in HF patients, it could be suggested that a more comprehensive ablation strategy should be applied for these patients. Purpose To examine the risk of AF recurrence and HF admission by ablation strategy for patients with AF and HF. Method This nationwide cohort study was conducted using real-life data from Danish healthcare registries. All patients above 18 years of age, with a diagnosis of AF and HF that underwent first-time CA from January 1st 2010 to December 31st 2018, were identified and included at the date of ablation. Exposure of interest was ablation strategy - pulmonary vein isolation (PVI) or additional ablation to PVI (PVI plus). PVI plus was defined as either roofline, mitral linear ablation, posterior wall isolation, complex fractionated atrial electrograms or ganglionated plexi ablation. Primary endpoint was HF admission and AF recurrence after a 3-months blanking period. AF recurrence was defined by a composite endpoint of first-reached endpoint of either use of antiarrhythmic drugs, AF admission, electrical cardioversions, or AF re-ablation. The relative rates of recurrent AF and HF admission by ablation strategy (PVI or PVI plus) were examined by Cox proportional models using PVI as reference. The analyses were adjusted for clinically important baseline characteristics including age, sex, AF type (paroxysmal or persistent), diagnosis-to-ablation time, procedural year, body mass index, size of left atrium, as well as co-morbidities such as ischemic heart disease, chronic obstructive pulmonary disease, chronic kidney disease, hypertension, and diabetes. Results The study cohort consisted of 1,270 patients diagnosed with AF and HF undergoing first-time CA, of which 1,119 (88%) received PVI and 151 (12%) received PVI plus. 80% where males in both groups. Median age was 62 for the PVI group and 64 for the PVI plus group. Severely enlarged left atrium, ischemic heart disease and use of amiodarone were more prevalent in the PVI plus group compared to the PVI group (Table 1). The relative risk of recurrent AF showed a hazard ratio of 1.02 (95% CI: 0.77-1.37) for the PVI plus group compared to the PVI group, and for HF admission the hazard ratio was 0.95 (95% CI: 0.55-1.65) for the PVI plus group compared to the PVI group (Figure 1). Conclusion No significant differences in AF recurrence and HF admission were observed between PVI and PVI plus strategy in AF and HF patients in this observational study. With a diagnosis-to-ablation time exceeding 3 years, it could be argued that advanced atrial remodelling may diminish the impact of reverse atrial remodelling after catheter ablation, irrespective of the ablation strategy employed.Table 1Figure 1