«Grey zone» of heart failure

Abstract

The review is devoted to modern understanding of heart failure with mid-range ejection fraction. The formation of the paradigm of «two phenotypes» of heart failure began around the end of the last century. As a result of a number of large epidemiological studies on heart failure with preserved ejection fraction, so-called «grey zone» of ejection fraction values was formed in the range of about 40-50%. This situation arose because of the lack of clearly established level of normal ejection fraction and underlines imperfection of this parameter as the only classification criterion. But no more convenient «tool» for research work was offered. In the past decade, «grey zone» of heart failure has been actively explored by clinical epidemiologists and clinicians. Should we classify these patients as one of the existing phenotypes of heart failure or present them as a new, separate phenotype? Both the first and second decisions require information about the population «portrait» of subgroup, about their response to treatment, and presumptive pathophysiological mechanisms of heart failure. In 2016 European society of cardiology guidelines for the diagnosis and treatment of acute and chronic heart failure, heart failure with mid-range ejection fraction was determined as a separate subgroup to stimulate the search for such data. At the moment mid-range ejection fraction is known to be recorded in about 10-20% of patients with heart failure. They have substantial comorbidities as patients with preserved ejection fraction but the prevalence of ischemic heart disease in this subgroup makes it similar to heart failure with reduced ejection fraction. The response to treatment with beta-blockers and aldosterone antagonists is similar to that of heart failure with reduced ejection fraction. It is important that the mortality rates in all three groups of patients are approximately the same. This circumstance underlines the importance of further searche. Perhaps the research of «grey zone» of the syndrome will help to better understand pathophysiology of the existing heart failure phenotypes and confirm the validity of their identification based on ejection fraction.