Background: A significant number of heart failure (HF) patients with reduced left ventricular ejection fraction (LVEF) experience ventricular function recovery during follow-up. We studied the variables associated with LVEF recovery in patients treated with sacubitril/valsartan (SV) in clinical practice. Methods: We analyzed data from a prospective and multicenter registry including 249 HF outpatients with reduced LVEF who started SV between October 2016 and March 2017. The patients were classified into 2 groups according to LVEF at the end of follow-up (> 35%: group R, or ≤35%: group NR). Results: After a mean follow-up of 7 ± 0.1 months, 62 patients (24.8%) had LVEF > 35%. They were older (71.3 ± 10.8 vs. 67.5 ± 12.1 years, p = 0.025), and suffered more often from hypertension (83.9 vs. 73.8%, p = 0.096) and higher blood pressure before and after SV (both, p < 0.01). They took more often high doses of beta-blockers (30.6 vs. 27.8%, p = 0.002), with a smaller proportion undergoing cardiac resynchronization therapy (14.8 vs. 29.0%, p = 0.028) and fewer implanted cardioverter defibrillators (ICD; 32.8 vs. 67.9%, p < 0.001), this being the only predictive variable of NR in the multivariate analysis (OR 0.26, 95% CI 0.13-0.47, p < 0.0001). At the end of follow-up, the mean LVEF in group R was 41.9 ± 8.1% (vs. 26.3 ± 4.7% in group NR, p < 0.001), with an improvement compared with the initial LVEF of 14.6 ± 10.8% (vs. 0.8 ± 4.5% in group NR, p < 0.0001). Functional class improved in both groups, mainly in group R (p = 0.035), Díez-Villanueva et al. with fewer visits to the emergency department (11.5 vs. 21.6%, p = 0.07). Conclusions: In patients with LVEF ≤35% treated with SV, not carrying an ICD was independently associated with LVEF recovery, which was related to greater improvement in functional class.