Heart failure with mid-range ejection fraction: are there clinical reasons in introduction of this new group as a distinct entity?

The article discusses the clinical expedience of isolating into a separate classification subgroup of patients with heart failure and a mid‑range ejection fraction (EF) of 40–49 %. Analysis of studies 2017–2018 focusing on the issue of patients with mid‑range LV EF showed that this subgroup is highly heterogenous and by some clinical and demographic parameters takes an intermediate position between heart failure (HF) patients with reduced (<40 %) and preserved (>50 %) LV EF. However, patients with mid‑range LV EF positively respond to beta‑blocker and RAAS inhibitor therapy, and their response is close to that of patients with reduced LV EF. This is a principal difference between patients with mid‑range and preserved LV EF who generally do not display any beneficial effect of such therapy. One of the major causes for such difference is a dissimilarity of HF etiology and, hence, pathogenesis in patients with reduced and mid‑range LV EF: primarily IHD (so‑called “ischemic” phenotype) in patients with reduced and mid‑range LV EF and non‑cardiac causes (“non‑ischemic” phenotype) in patients with preserved LV EF. Since the nonischemic phenotype is also rather common among patients with mid‑range LV EF a new HF classification should definitely indicate, in addition to LV EF, the clinical phenotype of disease, which is particularly important for patients with mid‑range LV EF of 40–49 %. Further studies should focus on variants of HF clinical phenotypes.