Introduction: Ventricular remodeling is a mal-adaptive process. Both angiotensin-converting enzyme inhibitors and sacubitril/valsartan have been shown to reverse remodeling in mostly uncontrolled observational studies. There is a lack of head-to-head studies. Methods: This cohort study compares the remodeling effects of angiotensin receptor blockers combined with a neprilysin inhibitor (ARNI) and perindopril in heart failure with reduced ejection fraction (HFrEF) patients between January 2017 and December 2020. Inclusion criteria: (i) age > 18 years, (ii) recent diagnosis of de-novo HFrEF (EF