Ejection fraction:
normal values, low or preserved, and what it means

Article written and reviewed by Dr Luca Moretti

Ejection fraction, often abbreviated as EF or LVEF when referring to the left ventricle, indicates what percentage of the blood contained in the ventricle is ejected with each contraction. If an echocardiogram reports, for example, an EF of 40%, this means that about 40% of the volume present in the ventricle at the end of filling is ejected with each systole.
EF is an important measurement, but by itself it does not measure how well the heart as a whole is functioning and, in isolation, it cannot diagnose or rule out heart failure.

In practical terms, three concepts must be distinguished:

• the echocardiographic EF value and its normal reference range;
• the classification of heart failure according to EF;
• the patient's actual clinical condition, which also depends on symptoms, cardiac filling, valves, rhythm, and the cause of the heart disease.

The 2026 ESC guidelines simplified the classification of heart failure: heart failure with reduced ejection fraction now includes patients with EF below 50%, whereas heart failure with preserved ejection fraction refers to an EF of at least 50% in the appropriate diagnostic context.

What ejection fraction actually measures

The ventricle does not empty completely with each heartbeat. EF is calculated by comparing the volume present at the end of diastole with the volume remaining at the end of systole. In formula terms, it represents the percentage of end-diastolic volume that is ejected during contraction.
This means that an EF of 60% does not mean the heart is working at "60% of its capacity", and an EF of 30% does not mean that the heart is functioning at only 30%. It is a specific measure of systolic pumping function, not a general percentage of heart health.

EF is measured mainly by echocardiography. The biplane Simpson method is one of the most commonly used standards; some laboratories may also use three-dimensional echocardiography, cardiac magnetic resonance imaging, or other techniques. The measurement depends on image quality and can vary slightly from one examination to another.

Which values are considered normal

Reference documents for echocardiographic cardiac chamber quantification indicate a lower limit of normal EF of approximately 52% in men and 54% in women. In clinical practice, however, the value is interpreted together with the method used, the laboratory, and the characteristics of the individual.
For this reason, it is not correct to automatically consider every value of 50-52% abnormal or, conversely, to regard every EF just above 50% as certainly normal without examining the rest of the echocardiogram.

The classification of heart failure does not perfectly coincide with echocardiographic normal ranges. The 2026 ESC guidelines chose a simple clinical threshold: EF <50% for HFrEF and EF ≥50% for HFpEF. The previous HFmrEF category, which included 41-49%, is no longer retained as a separate phenotype in the new European guidelines.

What it means to have a low ejection fraction

A reduced EF indicates that the left ventricle ejects a smaller-than-expected proportion of blood with each contraction. There can be many causes: previous myocardial infarction, cardiomyopathies, myocarditis, some valvular diseases, persistent tachyarrhythmias, drug toxicity, or other myocardial disorders.
However, the value alone does not determine clinical severity. Two people with an EF of 35% may have very different symptoms, exercise capacity, blood pressure, arrhythmias, and prognosis.

The relationship between EF and symptoms is not linear either. Some patients with a very low EF may be relatively stable, while others with more moderate reductions may have significant symptoms. Assessment must therefore also include congestion, right ventricular function, valves, heart rhythm, natriuretic peptides, and comorbidities.

Preserved ejection fraction does not mean a normal heart

One of the most misleading ideas is that an EF of 55-60% automatically rules out heart failure. In heart failure with preserved ejection fraction, the ventricle may eject an apparently normal percentage of its volume but may have impaired relaxation, increased stiffness, abnormal filling, or other abnormalities that lead to elevated intracardiac pressures.
Diagnosing HFpEF therefore requires more than reading "EF 60%" on a report: compatible symptoms or signs and other objective evidence of abnormal cardiac structure or function must be present.

Left ventricular hypertrophy, atrial enlargement, abnormalities of diastolic function, increased pulmonary pressure, or abnormalities of right ventricular function can also be clinically important despite preserved EF. The echocardiogram must therefore be interpreted as a whole.

When ejection fraction improves

EF can increase after treatment of the cause and initiation of heart failure therapy. The concept of heart failure with improved ejection fraction describes patients who previously had reduced EF and subsequently show significant recovery. The 2026 Second Universal Definition considers a previous HFrEF followed by an increase of at least 10 percentage points to an EF above 40% characteristic of this condition.
An improvement in EF is generally a favorable sign, but it does not necessarily amount to permanent recovery.

Structural abnormalities, a predisposition to relapse, or other signs of disease may persist even when EF returns to the normal range. The 2026 ESC guidelines therefore recommend continuing foundational therapy at the highest tolerated doses even in patients who become asymptomatic or show improvement in EF, except in selected situations assessed by a specialist.

Why the value can change between two echocardiograms

A difference of a few percentage points does not necessarily mean that the heart has truly improved or worsened. EF has measurement variability related to image quality, definition of the endocardial borders, the operator, and the method used. Heart rate, blood pressure, hydration status, and loading conditions can also influence the value measured at that moment.
When comparing two examinations, it is therefore more useful to assess the overall trend, preferably using comparable methods, rather than focusing on minimal differences.

If EF changes significantly, the cardiologist interprets the finding together with symptoms, treatment, and other echocardiographic measurements. In uncertain cases, or when particularly precise measurement is required, cardiac magnetic resonance imaging can provide highly accurate quantification of ventricular volumes and function.

Frequently asked questions about ejection fraction

What is a normal ejection fraction?
Echocardiographic reference values depend on sex, measurement method, and laboratory. In cardiac chamber quantification documents, the lower limit of normal is approximately 52% in men and 54% in women. In practice, an EF around or above 50% is often described as preserved, but it must be interpreted in the clinical context.

Is an ejection fraction of 40% severe?
An EF of 40% indicates reduced left ventricular systolic function, but overall severity does not depend on that number alone. Symptoms, cause, valves, rhythm, blood pressure, kidney function, and response to treatment influence the clinical picture and prognosis.

Can you have heart failure with a normal ejection fraction?
Yes. In heart failure with preserved ejection fraction, EF may be at least 50%, but the heart has other structural or functional abnormalities and elevated filling pressures that cause symptoms and signs of heart failure.

Can ejection fraction improve with treatment?
Yes. In some patients, EF increases substantially after treatment of the cause and heart failure therapy. Improvement does not necessarily mean permanent recovery, and effective treatment generally should not be stopped without specialist advice.

Can two echocardiograms give different ejection fraction values?
Yes. There is variability related to technique, image quality, the operator, and hemodynamic conditions at the time of the test. Small differences between two studies do not necessarily indicate a true change in cardiac function.