Heart Failure With Mildly Reduced Ejection Fraction: A Heart Failure Society of America Scientific Statement.

Heart failure (HF) has been categorized for years according to ejection fraction (EF) into patients with reduced (HFrEF) and preserved EF (HFpEF). In 2016, guidelines from the European Society of Cardiology recognized a third group, initially termed HF with mid-range EF (HFmrEF, originally 40-49%, but now modified to 41-49%), which has more recently been renamed HF with mildly reduced EF. HFmrEF predictably shares features with both HFrEF and HFpEF, but evidence to guide treatment is limited because clinical trials specifically restricted to this patient population have been lacking. The purpose of this Heart Failure Society of America Scientific Statement is to provide a comprehensive review of the epidemiology, clinical characteristics, and pathophysiology and to put forth a clinical framework for the treatment of patients with HFmrEF, for whom randomized trial data are limited.