Background: US guidelines recommend that patients with heart failure with reduced ejection fraction (HFrEF), who tolerate an ACEI (angiotensin-converting enzyme inhibitor) or ARB (angiotensin II receptor blocker), be switched to sacubitril/valsartan to reduce morbidity and mortality. We compared characteristics and healthcare utilization between Veterans with HFrEF who were switched to sacubitril/valsartan versus maintained on an ACEI or ARB. Methods: retrospective cohort study of treated HFrEF (July 2015-June 2017) using Veterans Affairs data. The index date was the first fill for sacubitril/valsartan and if none, for an ACEI or ARB. Treated HFrEF was defined by (1) left ventricular ejection fraction ≤40%, (2) ≥1 in/outpatient HF encounter, and (3) ≥1 ACEI or ARB fill, all within 1-year preindex. Poisson regression models were used to compare baseline characteristics and 1:1 propensity score-matched adjusted 4-month follow-up healthcare utilization between sacubitril/valsartan switchers and ACEI or ARB maintainers. Results: Switchers (1612; 4.2%) were less likely than maintainers (37 065; 95.8%) to have a history of myocardial infarction or hypertension, and more likely to be black, have a lower left ventricular ejection fraction, and higher preindex healthcare utilization. Switchers were less likely to experience follow-up all-cause hospitalizations (11.2% versus 14.0%; risk ratio 0.80 [95% CI, 0.65-0.98], P value 0.035). Conclusions: Few Veterans with treated HFrEF were switched to sacubitril/valsartan within the first 2 years of Food and Drug Administration approval. Sacubitril/valsartan use was associated with a lower risk for all-cause hospitalizations at 4 months follow-up. Reasons for lack of guideline-recommended sacubitril/valsartan initiation warrant investigation and may reveal opportunities for HFrEF care optimization.