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Is ejection fraction in heart failure a limitation or an opportunity?

The quantity ‘ejection fraction’ (EF) is among the most ingrained and commonly used quantities in clinical medicine. EF is used in heart failure (HF) for diagnosis, characterization, prognosis, patient triage, and treatment selection,1 and continues to be a fundamental entry criterion for HF and post-myocardial infarction clinical trials. HF with reduced EF (HFrEF; EF <40%) is well characterized and treatable; HF with preserved EF (HFpEF; EF ≥50%) is a common and complex syndrome so far without evidence-based therapy; and HF with mid-range EF (HFmrEF; EF 40–49%) was recently introduced to distinguish the grey zone where EF is not normal but there is no evidence-based therapy.1 However, concurrent with improved understanding of different EF phenotypes,2 an increasing criticism of EF as a measurement and concept has emerged, and in this issue of the Journal, Mele et al. offer a critical appraisal of the EF quantity.3 Are these concerns reasonable? What are the unmet needs in HF? They are: (i) improved resources and logistics for increasing HF care needs; (ii) improved utilization of existing evidence-based therapies in HFrEF; and (iii) evidence for existing and novel interventions in HFpEF (and HFmrEF) as well as in acute HF. Heart failure affects more than 2% of the population,4 is the most common cause of hospitalization,5 and is among the most common causes of death, with mortality at 1 year in population-wide registries ranging between 10% and 35%.6,7 Moreover, health care-related costs associated with an increasing HF prevalence are projected to increase three-fold between 2010 and 2030.8 This means that every clinician encounters HF, and important patient conversations and treatment decisions occur in emergency departments, internal medicine, cardiology and geriatrics wards, intensive care and peri-operative settings, palliative, hospice, and home care, and outpatient care in the specialist, generalist, and primary care settings. HF care is sub-optimal in non-specialist settings.7,9 How could clinicians understand HF and make adequate treatment decisions in these diverse settings if not with the help of EF? In this context, EF is not a limitation but a tool. In HFrEF, we are excited about novel interventions and positive trials, but as clinician-scientists, we would make perhaps a greater difference if we developed tools to optimize utilization