Heart Failure with Mildly Reduced Ejection Fraction
Heart failure with LVEF 41–49%. An intermediate phenotype acknowledged by guidelines from 2016 onwards; therapeutic strategy borrows from both HFrEF and HFpEF.
HFmrEF, heart failure with a mildly reduced ejection fraction (41–49%), was introduced as a distinct phenotype in the 2016 ESC heart-failure guidelines and confirmed in the 2021 ESC and 2022 ACC/AHA/HFSA guideline updates.
Patients with HFmrEF have outcomes intermediate between HFrEF and HFpEF and respond to many of the same therapies as HFrEF, particularly in subgroups with prior reduced EF that has improved with treatment.
Accurate LVEF placement at the HFrEF / HFmrEF / HFpEF boundaries (40% and 50%) directly affects guideline-directed therapy decisions, reinforcing the value of reproducible AI-assisted LVEF measurement.