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What is Ejection Fraction - EF?

An ejection fraction (EF) is one of the measurements used by your doctor to tell how well your heart pumps with each beat.

Ejection refers to the amount of blood that is pumped out of the left ventricle – the main pumping chamber – during each heart beat.
Fraction refers to how that amount compares to the total amount of blood in the left ventricle.

Therefore, an ejection fraction is the percentage of blood pumped out of the left ventricle with every heartbeat.

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What does the number mean?

A normal heart pumps a little more than half of the left ventricle’s blood volume with each beat. A normal EF is 50% or higher. For example, an LVEF of 55% means that 55% of the total amount of blood in the left ventricle is pumped out with each heart beat. The heart would not ever achieve an EF of 100% since it does not pump out all of the blood it holds at one time.¹

A lower than normal EF, less than 40%, indicates that the left ventricle is weakened.¹

Importantly, if your EF is 35% or less, you are at a higher risk of experiencing life-threatening irregular heartbeats that can cause sudden cardiac arrest and sudden cardiac death.¹ Ask your healthcare provider if an implantable cardioverter defibrillator (ICD) is appropriate for you.

How is EF measured?

Your ejection fraction can be measured in many ways, but one of the most common is with an echocardiogram or echo test.

An echocardiogram is a simple and painless test that uses sound waves to take moving pictures of your heart. The technology is the same used to perform a sonogram on a pregnant woman.

Figure 1. Echocardiogram imaging. This is an example of a normal echocardiogram. The yellow line is an outline of the left ventricle; the straight line highlights the middle of the left ventricle. [Photo credit: Angelo Auricchio, MD, PhD, Division of Cardiology, University Hospital, Magdeburg, Germany. 2002.]

This procedure is sometimes done right in the clinic, depending on your doctor’s specialty or the availability of the equipment.

Other tests can also be used to measure EF.

MUGA (multiple-gated acquisition) scan is a type of radionuclide imaging test that provides clear pictures of blood flow through the heart’s chambers and blood vessels. Also called a nuclear medicine scan.

Cardiac catheterization threads a catheter through a blood vessel into the heart to gather information about the coronary arteries and the heart’s other structures.

Why should I know my EF number?

If you have a heart condition, it is important for you and your doctor to know your EF. Your EF can help your doctor determine the best course of treatment for you and the effectiveness of the therapies that have been prescribed.

EF is measured initially when you are first diagnosed with a heart condition, and again as needed, based on changes in your condition. If you have an EF of less than 35%, you are a higher risk of experiencing life-threatening irregular heartbeats that can cause sudden cardiac arrest and sudden cardiac death.¹

Ask your healthcare provider how often you should have your EF checked.

¹ Bruce Wilkoff, et al. Understanding Your Ejection Fraction. Cleveland Clinic, 2008. http://my.clevelandclinic.org/heart/disorders/heartfailure/ejectionfraction.aspx. Accessed 2.12.09

Talk to your doctor about important safety information.