[Guidelines of the ESC 2021 on heart failure]

The new 2021 guidelines of the European Society of Cardiology (ESC) for the diagnosis and treatment of acute and chronic heart failure include a new terminology for heart failure (HF) with a left ventricular ejection fraction (EF) of 41-49%. This group of patients is now defined as HF with mildly reduced EF (HFmrEF; formerly mid-range). For this form of HF there are now for the first time recommendations for treatment with the standard medications, which are also used for HFrEF. Also new is a class I recommendation for the treatment of HFrEF patients with or without diabetes mellitus with sodium-glucose cotransporter 2 inhibitors (SGLT2i). It must be emphasized that all HFrEF patients should be treated with a combination of four drugs consisting of an angiotensin receptor-neprilysin inhibitor (ARNI) or angiotensin-converting enzyme (ACE) inhibitor, beta blocker, mineralocorticoid receptor antagonist (MRA) and SGLT2i. The primary treatment with ARNI can also be considered without the previous use of an ACE inhibitor. Primary prophylactic implantation of an implantable cardioverter defibrillator (ICD) continues to be a class I indication for patients with an EF of 35% or less in cases of ischemic cardiomyopathy; however, in cases of a non-ischemic cause there is a class IIa indication. This article summarizes these and further important novelties of the 2021 ESC guidelines taking the underlying clinical studies into account.