Heart Failure With Mid-range Ejection Fraction.

PURPOSE OF REVIEW: To describe the epidemiology, pathophysiology, management, and prognosis of patients with heart failure with mid-range ejection fraction (HFmrEF).

RECENT FINDINGS: In 2013, The American Heart Association (AHA)/American College of Cardiology (ACC) assigned an ejection fraction (EF) range to heart failure with reduced ejection fraction (HFrEF, EF ≤ 40%) and heart failure with preserved ejection fraction (HFpEF, EF ≥50%). This classification created a "gray zone" of patients with EFs between 41% and 49% that ultimately came to be known as heart failure with borderline or mid-range ejection fraction. HFmrEF patients represent a group with heterogeneous clinical characteristics that at times resembles HFrEF, at others HFpEF, and at others still a unique phenotype altogether. No randomized controlled trials exist in those with HFmrEF, though HFrEF and HFpEF studies that include overlap suggest some potential benefit of beta blockers, angiotensin receptor blockers, mineralocorticoid receptor antagonists, and angiotensin receptor-neprilysin inhibitors. Mortality rates among the HFmrEF population are significant, and are similar to those in patients with HFrEF and HFpEF. HFmrEF is a complex disorder that remains poorly understood. Future research is needed to better elucidate the pathophysiology, management, and prognosis of this condition.