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Understanding Heart Function: What Is The Ejection Fraction?

Heart failure is a serious, long-term condition that occurs as a result of damage to the heart muscle. This can be from any number of reasons such as heart attacks, valve problems, etc. When there is suspicion that the heart is damaged, your provider may order a special test that measures heart function. This test is called an "ejection fraction" (EF), and is a key measure of how well the heart works. Your provider might refer to it as the "EF." Your heart ejection fraction can be measured in a number of different ways. An echocardiogram is the most common method used. The ejection fraction is one of the best measures of how well the heart is working. Many patients find the terminology is confusing, so we would like to take this opportunity to explain the ejection faction.

The ejection fraction is expressed as a percentage. This can be misleading for patients. For instance, you may hear that your ejection fraction is 50% and become upset thinking your heart is only working at half the capacity of what it should be. That is not the case. To help you understand ejection fraction we will explain where that number comes from.

The ejection fraction represents the amount of blood the heart pumps during each beat. It is the amount of blood in the heart at the end of the pumping cycle. This is compared to the amount of blood that is in the heart just before the heart beats, at the end of the filling cycle. Ejection fraction is then expressed as a ratio, or as a percentage. Here are some examples:

  • The heart contains 100 cc of blood at the end of the filling cycle.

  • The heart pumps 50 cc of blood with each beat, and it has 50 cc of blood in the heart at the end of the heartbeat. In this case the heart emptied 50% of the blood in the chamber. Using the equation below we determine the ejection fraction to be 50/100 = 0.50, so 50% is the ejection fraction.

  • If only 40 cc of blood remains in the heart, the heart pumped out 60 cc of blood, and the ejection fraction is 60%

  • If 70 cc of blood remains in the heart and only 30 cc of blood is pumped out, then the ejection fraction is 30%

A normal ejection fraction is around 55% or higher, so that with each beat, the heart empties a little over half of the blood in the chamber. An ejection fraction of 50% is actually only slightly reduced and might be called ┬┐low normal'. This probably would not really have much of an effect on your ability to function. If you hear your ejection fraction is 60%, this is normal.

However, when the ejection fraction gets below 40% there may be some limits on your exercise capacity. When your ejection fraction is around 20%, heart function is more seriously limited. In this case, a person's ability to exercise could be greatly limited. When this condition is managed closely, people with a low ejection fraction often do quite well. Patients with a low ejection fraction do best when they are an active partner in the process.

More than 5 million Americans are living with heart failure, and 550,000 new cases are diagnosed each year. Heart failure is one of the most common reasons for admission to the hospital. The good news is that many people with heart failure live a long and enjoyable life. With the right treatments, medications, attention to diet, exercise and lifestyle changes, many live long healthy lives. Patients with heart failure can manage this condition, and your VA healthcare team is here to help.

Learn More

What is Heart Failure? (Veterans Health Library)

Heart Failure: Being Active (Veterans Health Library)

Heart Failure (Medline Plus)