<h4>Background</h4>Evidence regarding the prognostic impact of angiotensin-converting enzyme inhibitors (ACEi) vs. receptor blockers (ARB) in heart failure with mildly reduced ejection fraction (HFmrEF) is limited.<h4>Methods</h4>We retrospectively studied consecutive patients hospitalized with HFmrEF from 2016 until 2022 at a German university hospital. This evidence concerns the gene ACE and heart failure.