Background/Objectives: Angiotensin receptor–neprilysin inhibitor (ARNI) has a well-established advantage over angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ACEI/ARB) therapy in patients (pts) with heart failure with reduced ejection fraction (HFrEF), but in pts after acute myocardial infarction (AMI) with left ventricular (LV) systolic dysfunction, the advantage of ARNI has not been clearly proven. The gene discussed is MME; the disease is acute myocardial infarction.