From the Guidelines
The ejection fraction is a measure of how much blood the left ventricle of the heart pumps out with each contraction, and it is classified into three categories: Heart Failure with Reduced Ejection Fraction (HFrEF) with an LVEF ≤40%, Heart Failure with Mildly Reduced Ejection Fraction (HFmrEF) with an LVEF of 41% to 49%, and Heart Failure with Preserved Ejection Fraction (HFpEF) with an LVEF ≥50%.
Key Points
- The classification of heart failure (HF) by left ventricular ejection fraction (LVEF) is important for prognosis and treatment response 1
- HFrEF is defined as LVEF ≤40% and is often associated with a worse prognosis and response to treatments 1
- HFmrEF is defined as LVEF of 41% to 49% and represents a dynamic trajectory to improvement or deterioration 1
- HFpEF is defined as LVEF ≥50% and represents at least 50% of the population with HF, with its prevalence increasing 1
Classification of HF by LVEF
- HFrEF: LVEF ≤40%
- HFmrEF: LVEF of 41% to 49%
- HFpEF: LVEF ≥50% The diagnosis of HFmrEF and HFpEF can be challenging and requires additional objective measures of cardiac dysfunction, such as elevated natriuretic peptide levels or evidence of increased LV filling pressures 1.
From the Research
Definition of Ejection Fraction
- Ejection fraction (EF) is defined as the ratio of end-systolic volume (ESV) and end-diastolic volume (EDV) 2
- It is a dimensionless number that represents the proportion of blood that is ejected from the left ventricle with each heartbeat
Calculation of Ejection Fraction
- Ejection fraction is calculated as the stroke volume divided by end-diastolic volume 3
- The estimation of ejection fraction is generally based on geometric assumptions that allow for assessment of volumes based on linear or two-dimensional measurements
Limitations of Ejection Fraction
- Ejection fraction has several important limitations, including being preload- and afterload-dependent, and only moderately reproducible 3
- It represents only a single measure of risk in patients with heart failure, and its relationship with risk is modified by factors such as hypertension, diabetes, and renal function 3
- Ejection fraction is less useful as a marker of risk as it approaches normal 3
Clinical Use of Ejection Fraction
- Ejection fraction is widely recognized as a valuable diagnostic and prognostic tool in cardiology 4
- It is used in a variety of settings, including heart failure, myocardial infarction, and valvular heart disease 4
- However, its use has been criticized for being an oversimplification of the complex pathophysiology of heart failure 5
Alternative Metrics
- Some studies suggest that end-systolic volume (ESV) may be a more logical metric for the analysis of ventricular function than ejection fraction 2
- A multiparametric evaluation that considers other parameters, such as LVEF changes over time, HF aetiology, co-morbidities, and other imaging parameters, may provide a more comprehensive understanding of heart failure 6