Ejection Fraction: How Is It Measured?

Medically Reviewed by Zilpah Sheikh, MD on February 06, 2024
Written by Hope Cristol, Stephanie Langmaid
5 min read

Ejection fraction (EF) measures the amount of blood pumped out of your heart's lower chambers, or ventricles. It's the percentage of blood that leaves your ventricle when your heart contracts. The term usually refers to just the left ventricle.

Measuring your ejection fraction can help doctors figure out whether you have certain heart problems, especially one type of heart failure. Despite the scary-sounding name, heart failure doesn't mean your heart stops; it just means it can't pump as much blood as your body needs. Your ejection fraction will also help the doctor decide which treatments are best for you and whether your treatment is working.

Left Ventricular Ejection Fraction (LVEF)

Your left ventricle pumps blood that's been enriched with oxygen through your aorta to the rest of your body. The LVEF can show the extent of damage from a heart attack, long-term high blood pressure, left-sided heart failure, or chemotherapy.

Right Ventricular Ejection Fraction (RVEF)

Your right ventricle takes blood that's come back to your heart and pumps it into your lungs where it picks up oxygen. Your doctor will measure RVEF if you have right-sided heart failure, which is less common. 

There are a few ways your doctor can find out your EF percentage. You'll probably have one of these tests:

  • Echocardiogram, or "echo." A technologist puts a handheld wand on your chest. It uses ultrasound waves to take pictures of your heart.
  • MRI. You lie on a bed that slides into a large magnetic tube. MRI uses a magnet, radio waves, and a computer to create pictures of the inside of your body, in this case your heart.
  • Nuclear stress test or multigated acquisition scan (MUGA). Your doctor injects a small amount of radioactive dye into your vein. As it moves through your heart, a camera makes images of your heartbeats.

Your ejection fraction is a percentage. It's calculated by dividing the volume of blood pumped out of the ventricle each time your heat beats (called stroke volume, or SV), by the total amount of blood in the ventricle (called end-diastolic volume, or EDV). Then you multiply the result by 100. 

The formula looks like this: EF = (SV/EDV) x 100.

Many doctors consider a normal ejection fraction to be 55%-75%. If yours is 50% or lower, it's a sign that your heart--usually your left ventricle--may not pump out enough blood.

There's a gray area when your EF is between 50% and 55%. Some experts call this borderline.

A normal EF doesn't always mean your heart is healthy. You could have heart failure with preserved ejection fraction (HFpEF). It happens when your heart muscle thickens to the point that the left ventricle holds less than the usual amount of blood. Even if that chamber pumps the way it should, it doesn't release as much oxygen-rich blood as your body needs.

HFpEF Causes

The health conditions that can lead to HFpEF include:

  • High blood pressure
  • Diabetes
  • Irregular heartbeat
  • Heart valve defects
  • Obesity
  • Kidney disease
  • Chronic obstructive pulmonary disease (COPD) 

It's more common in women, smokers, and older people. 

HFpEF Treatment

Medication options include diuretics and other medicines that lower your blood pressure. 

If your doctor says your ejection fraction is too low, under 50%, it means there may be a problem with your heart.

With a low ejection fraction, you might have symptoms like:

A low ejection fraction could be a sign of a condition such as:

  • Damage from a heart attack
  • Heart muscle diseases (cardiomyopathy)
  • Heart valve problems
  • High blood pressure that hasn't been under control for a long time

Medications can raise your ejection fraction and make you feel better. Your doctor may suggest:

  • Inotropes like digoxin. They help your heart contract better.
  • Angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), or angiotensin receptor neprilysin inhibitors (ARNIs) like sacubitril/valsartan (Entresto). They ease stress on your heart muscle.
  • Beta-blockers. They ease symptoms by slowing your heart rate a bit to lower its workload.
  • Diuretics. They help your body get rid of extra fluid from swelling.
  • Mineralocorticoid receptor antagonists. These diuretics help your body get rid of salt and fluid without losing potassium.

You might also need to make lifestyle changes such as:

  • Get regular physical activity at a level your doctor approves.
  • Take daily relaxation or rest periods.
  • Limit salt and excess fluids.
  • Cut out alcohol and tobacco.

A device like an implantable biventricular pacemaker or cardiac defibrillator can help your heart work better. It may also help some people who have a low EF live longer.

What to ask your doctor
Take an active role in your health, especially if you have a low EF. Keep up with your appointments. Have your doctor explain your condition and treatment options. Here's a list of questions you may want to ask:

  • What does my ejection fraction number mean for my health?
  • When should I have my EF tested again?
  • Should I take medications or make lifestyle changes?
  • Do I need any other tests?
  • Do you specialize in heart rhythm problems? If not, should I see a doctor who does?

If your ejection fraction is higher than 75%, it could be a sign of a condition called hypertrophic cardiomyopathy. It causes the walls of your heart to beat harder. They become thick and stiff, and your heart doesn't take in or pump out as much blood as usual.

Can ejection fraction improve in 3 months?

Yes. If you get treatment, like medication and exercise, for the problem that's causing your injection fraction to be low, you can see improvement within 3 months.

What is the lowest ejection fraction you can live with? 

According to experts, you can survive if your ejection fraction is as low as 5%. But your life expectancy at that point is quite low. 

How serious is a 25 ejection fraction?

It's very serious. With an EF of 25% or lower, your heart function is considered seriously impaired.