Introduction: Catheter ablation is a well-established therapy for atrial fibrillation (AF), with a promising impact on heart failure (HF) outcomes. We aimed to assess the impact of AF ablation on echocardiographic and clinical parameters in patients with HF, and to assess factors associated with improvement of the left ventricular ejection fraction (LVEF). Methods: Patients with HF and LVEF<50% who underwent radiofrequency AF ablation in 5 high-volume Brazilian centers were prospectively enrolled. All patients underwent transthoracic echocardiography before the procedure and during follow-up, and the analysis by the examiner was considered. The primary outcome was LVEF normalization (≥50%) at follow-up. Clinical, echocardiographic, and procedural variables associated with the primary outcome were assessed by logistic regression. Results: From 2018 - 2022, 85 patients were included, being 59 (69%) males, mean age 66±12 years. Of these, 27 were in NYHA functional class 3/4 and 71 (83%) had persistent AF. Pre-procedural LVEF was 38±7%, and 25 (29%) had LVEF<35%. Complications occurred in 3 patients (2 vascular access and 1 endocarditis). In the 12±10 month follow-up, there was a substantial improvement of the LVEF to 54±14% (p<0.001), and 60 (71%) achieved LVEF normalization. 59 patients (69%) had LVEF improvement ≥10%, only 6 remained in NYHA class 3/4, and AF recurred in 13 (15%). Three patients died during follow-up, and none had LVEF normalization. Predictors of LVEF normalization were: pre-ablation LVEF (OR=1.24, 95%CI 1.12-1.37), left atrial diameter (OR=0.88, 95%CI 0.82-0.95), Chagasic etiology (OR=0.14, 95%CI 0.03-0.77) and indication of amiodarone (OR=0.26, 95%CI 0.09-0.72) and ACEi/ARB (OR=0.25, 95%CI 0.08-0.75, p=0.02). In the multivariable model, independent predictors were: baseline LVEF (OR=1.25, 95% CI 1.10-1.41, p<0.001), left atrial diameter (OR=0.88, 95%CI 0.79-0.98, p=0.02), Chagasic etiology (OR=0.07, 95%CI 0.01-0.74, p=0.03) and indication of ACEi/ARB: (OR: 0.11, 95%CI 0.02-0.63, p=0.01). Conclusion: AF ablation in patients with HF resulted in echocardiographic and functional improvement, with low complication rates. Less clinical severity and morpho-functional impairment associated with LVEF normalization.