Understanding the Pathophysiology of Heart Failure with Mid-Range Ejection Fraction: A Comprehensive Narrative Review

Heart failure (HF) diagnosis, phenotyping, prognosis, and treatment decisions are all based on the left ventricular ejection fraction (EF). Heart failure with mid-range EF (HFmrEF) is a third EF category for heart failure with an EF between 40 and 49 percent. Comparatively, heart failure with preserved EF or reduced EF has been largely unexplored. 10–25% of patients with HF have HFmrEF. Although HFmrEF has an intermediate clinical profile, it is more similar to HF with reduced EF, particularly because these patients have a high incidence of ischaemic heart disease. Heart failure with preserved EF has a lower risk of cardiovascular events than heart failure with reduced EF, which is milder. HFmrEF and HF with preserved EF patients have a similar or higher risk of non-cardiovascular adverse events than patients with HF with reduced EF. There is still a great deal of mystery surrounding HFmrEF. The purpose of this review is to describe the major pathophysiology of HFmrEF and its similarities and differences with the other two types of EF. It is the purpose of this paper to present a comprehensive overview of the currently available evidence in support of the pathophysiology of patients with HFmrEF. Further investigation of the pathophysiology, treatment, and prognosis of this condition will be needed in the future in order to better understand it.