Time to rename the middle child of heart failure : Heart failure with mildly reduced ejection fraction

[Extract] The ‘middle child’ of heart failure (HF) [patients with left ventricular ejection fraction (EF) in the 40–50% range] was christened HF with mid-range EF in 2014,¹ in recognition of the large gap in treatment evidence in this neglected subgroup of HF, with prior clinical trial evidence limited to those patients with EF of 40% or lower, and recent attention being showered upon those with EF of 50% or greater. While the EF 40–50% group was recognized as a ‘grey area’ in prior European Society of Cardiology Heart Failure Guidelines,² the name ‘heart failure with mid-range EF’ and acronym ‘HFmrEF’ was adopted in the 2016 guidelines,³ with the intention of bringing attention to this group of patients and addressing the evidence gap. The adoption of this nomenclature has inspired hundreds of publications which show that HFmrEF constitutes almost a fifth of the HF population, with patient demographics intermediate between those with lower and higher EFs, high frequency of coronary artery disease, and better prognosis than those with lower EF.⁴