14/09/2026
Ejection Fraction EF
Ejection fraction measures the percentage of blood the left ventricle pumps out with each heartbeat. It is an important, but not complete, measure of heart function.
Formula
EF percent = Stroke Volume SV ÷ End-Diastolic Volume EDV × 100
- EDV: Amount of blood in the ventricle after it fills, just before contraction
- End-Systolic Volume ESV: Blood left after contraction
- SV: Blood pumped per beat
SV = EDV − ESV
Typical Left-Ventricular EF Ranges
• Normal: 50%–70% (Normal pumping function)
• Mildly Reduced: 41%–49% (Slightly weakened pump)
• Reduced: ≤ 40% (Significantly weakened pump)
• Hyperdynamic: > 70% (Contracts unusually hard)
Ranges may vary slightly by laboratory and imaging method.
What Does a Low EF Mean?
A low EF can indicate that the heart’s pumping ability is reduced. This may occur with heart failure, a previous heart attack, cardiomyopathy, or certain valve problems. However, EF alone does not diagnose heart failure.
Some people have heart failure with preserved EF. In this condition, the heart pumps out a normal percentage of blood but is stiff and does not fill properly.
How Is EF Measured?
It can be estimated using:
- Echocardiography, or echo, which is the most common method
- Cardiac MRI
- CT scan
- Nuclear imaging
EF results should be interpreted alongside symptoms, examination findings, and other tests.
