Ejection fraction (EF) is the percentage of blood your left ventricle — the main pumping chamber — pushes out with each beat.
If the chamber holds, say, 100 units before a beat and ejects 60, the EF is 60%. In most healthy hearts the number sits somewhere in the 50s to 70s. It is the number everyone quotes because it is simple — but simple numbers invite simple mistakes, and EF is misunderstood in both directions: people with a normal EF can still have serious heart problems, and people with a low EF can still have a long, good life ahead.
What the ranges usually look like
Teams describe EF loosely, and the boundaries are not laws of nature. Most teams would roughly describe:
| EF range | Plain-language description |
|---|---|
| 50% and above | Within the usual range — the pump squeezes normally. Note: a “normal pump” does not equal “no heart problem.” |
| 40–49% | Mildly reduced — the pump is a little weaker; often no symptoms at rest. |
| 30–39% | Moderately reduced — usually worth treating actively and watching closely. |
| Below 30% | Severely reduced — the pump is significantly weak; this is when treatment really matters and help is most available. |
Two cautions. First, the number depends on the tool: an echo, an MRI and a nuclear scan may give slightly different readings of the same heart, so a two-point change between tests is usually measurement noise, not a real change. Second, your team reads it in the context of your symptoms — the same EF can feel completely different in two different people.
What a low number means for real people
A low EF means the pump is weaker than usual, and the body notices: breathlessness, fatigue, swelling in the ankles — these are the classic companions. The good news is that a weak pump is one of the most-studied problems in all of medicine. There are medicines and, when appropriate, devices that help a weakened heart work better and protect it — and EF can improve over time with treatment. A low number today is a starting line, not a finishing line.
What a normal number does not tell you
A normal EF does not mean your heart is “fine.” The squeeze can be normal while the muscle is stiff, the valves leak, the rhythm is off, or the pipes are narrowed. EF is one chapter of a long book — most teams treat the whole book.
What to ask your team
- What is my EF, and how was it measured?
- What does my number mean in the context of my symptoms?
- Will we re-measure it — and when?
- If it is low, what does the treatment plan look like, and how will we know it is working?
Ask for the number written down, together with the date and the test it came from. Tracking EF over time is more useful than any single reading — you will be able to compare like with like.
You get sudden or worsening breathlessness, swelling in your ankles or belly, chest pain, or you faint or feel you might faint. These deserve a same-day call to your team — or emergency help if they come on fast.
EF is a useful number, not your identity. Let your team read it alongside your symptoms, your other tests and your life — and make the decisions with you, not at you.