It is over 4 years since the Prospective Comparison of angiotensin receptor/neprilysin inhibitor (ARNI) with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure (PARADIGM-HF) trial was published in New England Journal of Medicine. The PARADIGM-HF trial was the one that contributed to the official approval to use ARNI simultaneously with cardiac resynchronisation therapy (CRT) or implantable cardioverter-defibrillator (ICD) in patients who receive optimal medical treatment and still presented NYHA II-IV class symptoms according to the 2016 European Society of Cardiology Guidelines for the diagnosis and treatment of acute and chronic heart failure. The aim of this article is to summarise current knowledge on the activity of ARNI in a selected group of patients with heart failure with reduced ejection fraction (HFrEF) based on a recent PARADIGM-HF subanalysis in the field of renal function in patients with and without chronic kidney disease, glycaemia control in patients with diabetes, ventricular arrhythmias and sudden cardiac death and health-related quality of life. This article includes also recently announced findings on the TRANSITION study which revealed that HFrEF therapy with ARNI might be safely initiated after an acute decompensated heart failure episode, including patients with heart failure de novo and ACEI/ARB naïve, both hospitalised or shortly after discharge, in contrary to the PARADIGM-HF trial, where patients had to be administered a stable dose of an ACEI/ARB equivalent to enalapril 10 mg a day for at least 4 weeks before the screening.