An ejection fraction (EF) is one of the measurements used by physicians to assess how well a patient’s heart is functioning. “Ejection” refers to the amount of blood that is pumped out of the heart’s main pumping chamber during each heartbeat. “Fraction” refers to the fact that, even in a healthy heart, some blood always remains within this chamber after each heartbeat. Therefore an ejection fraction is a percentage of the blood within the chamber that is pumped out with every heartbeat. An EF of 55 to 75 percent is considered normal. A higher than normal ejection fraction could indicate the presence of certain heart conditions, such as hypertrophic cardiomyopathy. A low ejection fraction could be a sign that the heart is weakened.
Ejection fraction is an important tool in the diagnosis and monitoring of heart failure and certain types of cardiomyopathies. An ejection fraction of less than 40 percent may be present in these conditions. Heart failure occurs when one of the heart’s pumping chambers is not pumping well enough to meet the body’s needs. It is most commonly caused by coronary artery disease, poorly controlled high blood pressure (hypertension), and cardiomyopathy, which is a condition in which the heart is abnormally enlarged, thickened or stiffened.
About ejection fraction (EF)
An ejection fraction is the percentage of blood pumped out of a heart chamber during the contraction phase of each heartbeat (systole). The term typically refers to a measurement of the left ventricle (the lower left chamber of the heart), which pumps oxygen-rich blood out to the body through the aorta. An ejection fraction can also be measured in the right ventricle (the lower right chamber), which pumps blood returning from the body to the lungs for oxygen. However, this measurement is nearly always referred to as a right ventricular ejection fraction.
Even in a healthy heart, some blood always remains within the heart chambers after each heartbeat. Therefore an ejection fraction is a percentage of the blood within the chamber that is pumped out with every heartbeat. Normally, the left ventricle pumps 55 to 75 percent of the blood within that chamber out to the body with each heartbeat. A higher than normal ejection fraction could indicate the presence of certain heart conditions, such as hypertrophic cardiomyopathy.
An ejection fraction of less than 40 may indicate heart failure, a chronic condition in which at least one heart chamber is not pumping well enough to meet the body’s needs. Heart failure leads to congestion of blood vessels and fluid backup and swelling in the lungs, legs and ankles, shortness of breath, and fatigue. An ejection fraction between 40 and 50 percent may indicate damage to the heart muscle (e.g., from a prior heart attack). Typically, this EF level alone is not low enough to lead to heart failure.
A low ejection fraction may result from some kind of cardiomyopathy, a condition in which the heart is abnormally enlarged, thickened or stiffened. Low EF is an important risk factor for sudden cardiac death (SCD), a condition that occurs when the heart stops abruptly (cardiac arrest), usually as a result of ventricular fibrillation. Patients with a low EF are significantly more likely to suffer sudden cardiac death within two years than patients with a normal ejection fraction.
Measurement methods for ejection fraction
An ejection fraction is most commonly measured during an echocardiogram. This painless and noninvasive test uses high-frequency sound waves (ultrasound) to get a picture of the four heart chambers and the four heart valves. An ejection fraction can also be measured as part of other diagnostic testing, such as:
MUGA scan. A type of radionuclide imaging test that provides clear pictures of blood flow through the heart’s chambers and blood vessels.
Echocardiography. This test uses sound waves to visualize structures within the heart. It has the advantage of being noninvasive and relatively accessible. However, studies have shown that there is great variability in the test results, depending on the skill of the operator.
Cardiac catheterization. A test in which a catheter is inserted into a blood vessel and guided all the way to the heart in order to obtain information about the heart and the coronary arteries. Increasingly, this test is being replaced by noninvasive methods to measure ejection fraction.
SPECT test. Like the MUGA scan, this is a form of radionuclide imaging. When coupled with an electrocardiogram (ECG) test, it allows physicians to see how the heart functions at specific portions of the cardiac cycle. This is called a gated SPECT test. Because this test also measures the health of the heart muscle itself (by assessing how much blood the muscle absorbs), it can be helpful in certain situations when the health of the heart muscle is in question, such as after a heart attack.
Nuclear stress test. An exercise stress test performed before and after the administration of a radionuclide tracer (gated SPECT). It creates images of the heart before, during and after physical exertion. Therefore, an ejection fraction may be obtained at both rest and during exercise. This approach offers a very sensitive way to identify heart pump function.
Cardiac magnetic resonance imaging (MRI). A test that uses powerful magnets to visualize the heart’s structure. This test has very good resolution, but the patient is required to hold their breath during the test, a feat that may be difficult for patients with heart failure. Also, because this is newly adapted technology to measuring ejection fraction, it remains an expensive test that requires specialized training.
Computed tomography (CT) scan. This test uses x-ray scans that are detected by multiple sensors and then collated by computer into a three-dimensional image. Newer CT scanners have up to 64 scanners, allowing for very detailed images of the heart. However, because of the relatively high radiation exposure associated with this test, it's unlikely to be used for routine screening or evaluation unless the test is already being conducted for another reason.
Signs and symptoms of low ejection fraction
A low EF can lead to symptoms of heart failure, such as:
Shortness of breath or inability to exercise
Swelling (edema) of the feet and lower legs
Fatigue and weakness
Rapid, forceful, uncomfortable or obviously irregular heartbeat (palpitations)
Abdominal discomfort such as swelling, pain or nausea
Mental confusion
However, some patients have a very low EF (less or equal to 30) and yet have minimal or even no symptoms. Other signs of heart failure or cardiomyopathy may also accompany a low ejection fraction. These include:
An abnormal heart murmur (due to a heart valve disorder)
A crackling sound of fluid in the lungs (rales) due to pulmonary congestion
A rapid heartbeat (tachycardia) or other abnormal heart rhythms (arrhythmias)
Hypertrophy or enlargement of the heart
Liver malfunction
Congestion of the lungs
Swollen neck veins
Fluid retention with accompanying weight gain and ankle swelling
Treatment options for low ejection fraction
Management of the underlying condition (e.g., hypertension, coronary artery disease) is an essential step in the management of a low ejection fraction. It is important to note that low ejection fractions caused by conditions such as heart failure or cardiomyopathy are often irreversible. Treatment should be focused on reducing symptoms and preventing the progression of the disease. These strategies include lifestyle changes, medications and procedures such as the insertion of an implantable defibrillator (ICD).
Lifestyle choices that may be recommended to patients with an abnormal ejection fraction include:
Limiting physical activity until the appropriate level of activity is approved by one’s physician, and then staying as active as possible. Regular aerobic exercise may be recommended, while patients may be instructed to avoid weight training or lifting heavy objects.
Scheduling relaxation and rest periods throughout the day.
Eating a heart-healthy diet and avoiding excessive fluid intake.
Reducing salt intake.
Completely avoiding alcohol and/or tobacco use.
Keeping a daily weight diary and notifying a physician of any weight gain of three or more pounds in a single week (which may indicate fluid retention and the need for an immediate change in treatment).
A cardiac rehabilitation program may be recommended for patients with heart failure.
Medications to reduce the heart’s workload, increase blood flow, widen vessels or eliminate excess water from the body may be prescribed. These medications may include:
Inotropes (such as digoxin). Helps the heart to contract more vigorously and effectively, and helps to reduce symptoms.
ACE inhibitors. A type of vasodilator that expands blood vessels to allow blood to flow easier and more freely, allowing the heart to pump more efficiently. These agents are standard in the treatment of low ejection fraction, particularly in the presence of clinical heart failure. ACE inhibitors are also used to control and reduce high blood pressure (hypertension).
Angiotensin II receptor blockers. Similar to ACE inhibitors, these medications reduce the stress on the heart muscle and may benefit patients with diabetes and heart disease. The medication apparently protects the kidneys from the diabetes-related complications.
Diuretics. Medications that cause the kidneys to flush water and other substances (e.g. sodium) from the body through urine, thus reducing blood pressure.
Beta blockers. These medications may improve symptoms by slowing the heart’s contraction rate and reducing its pumping action, thus lessening the heart’s workload.
Alderosterone antagonists. These drugs are used to prevent sodium and water retention and scarring of the heart muscle. They are generally reserved for patients with more severe heart failure.
Depending upon the cause of the depressed ejection fraction, certain procedures may be recommended, such as the insertion of one of the following:
Implantable defibrillator (ICD). This implanted device monitors for and, if necessary, corrects an abnormal heart rhythm by sending electrical charges to the heart. An ICD may benefit patients who have experienced serious episodes of fainting (syncope) or arrhythmias associated with a low ejection fraction. In particular, ICDs are used to prevent ventricular fibrillation, an abnormal heart rhythm that can lead to rapid sudden cardiac death if not immediately treated. ICDs may also be built in to biventricular pacemakers. In select patients, biventricular pacemakers have appeared to improve ejection fraction and exercise tolerance. This form of therapy is known as cardiac resynchronization therapy.
Ventricular assist device. An implanted device that helps one of the heart’s lower chambers (ventricles) to pump blood. These are used primarily as a “bridge to transplant,” meaning that they help patients with low ejection fractions while they await a heart transplant.
A promising treatment being developed for depressed ejection fraction is gene therapy. Researchers continue to explore the nature of stem cells in the treatment of many diseases. Stem cells are immature cells, meaning they have the ability to develop into a variety of mature cells, such as red or white blood cells, platelets, heart muscle cells, brain cells, etc. For example, recent studies have reported encouraging findings after transplanting stem cells taken from patients’ own bone marrow into heart muscle following a heart attack.
For heart failure patients, bone marrow cells have been injected into the heart’s left ventricle. Other studies have shown promising results in the use of muscle cells taken from other parts of the body (e.g., thigh) and injecting them into damaged areas of the heart. It is believed that such skeletal muscle helps to restore the contractile properties of affected heart muscle, thus improving ejection fraction. However, these treatments are still experimental and have not been approved by the FDA.
Normal ejection fraction and heart failure
While an ejection fraction (EF) is a tool to diagnose systolic heart failure, or heart failure that occurs during the pumping phase of the heartbeat, it is possible for a person to have heart failure without having an abnormal ejection fraction. There are two phases to the heart’s pumping motion. First is the filling phase (diastole) in which the heart chamber fills with blood. Second is the emptying phase (systole) in which the blood is pumped out of the chamber to the body. An ejection fraction is a measurement of the amount of blood pumped out during this second, emptying stage.
Heart failure may be caused by problems with the heart’s emptying phase, its filling phase or with both phases. Therefore, a person whose heart failure is caused by a problem with the filling phase (diastolic heart failure) could have a normal ejection fraction.
Conditions that cause the heart muscle to stiffen may also cause heart failure without producing an abnormal ejection fraction. These conditions include cardiomyopathies in which the heart muscle becomes abnormally enlarged, thickened and/or stiffened. Other causes of heart stiffening include invasion of the heart muscle by foreign substances or fibrous tissue problems.
Finally, the ejection fraction is a measurement of the amount of blood pumped from the heart with each heartbeat. However, the number does not reflect the direction in which the blood is being pumped. If the valves are abnormal due to some form of valvular heart disease, blood may be flowing in the wrong direction. In this case, a patient might have a normal ejection fraction but an unhealthy heart. This can lead to heart failure with a normal ejection fraction (e.g., mitral insufficiency).
In the same way that blood pressure and heart rate typically increase during physical activity, a healthy person’s ejection fraction tends to increase about 5 percent while the person is exercising. When this healthy increase in EF during exercise does not occur, it indicates a heart function problem. Therefore a patient with a normal ejection fraction that fails to rise with exercise could be diagnosed with heart failure or cardiomyopathy. Such a problem may be diagnosed by a stress echocardiogram, in which the ejection fraction can be measured during both rest and exercise.
An ejection fraction is just one of many tools the physician uses to diagnose heart problems. One of its significant advantages is that it is easier for physicians to obtain this number through a simple, painless echocardiogram than to perform more extensive heart function tests. Consequently, the ejection fraction serves as a good baseline for monitoring the heart’s function over time.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to ejection fraction:
What is my ejection fraction?
Is it improving or worsening?
Are my symptoms due to a depressed ejection fraction?
What kind of treatment will I need? Medications? An implantable device? Both?
How often should I monitor the ejection fraction?
Is it possible to improve my ejection fraction? Will that relieve symptoms?
Can I exercise? Have sex?
Does this raise the risk of other cardiac conditions, such as arrhythmias?
If my disease continues to worsen, what are the treatment options?
Are there are any other tests that might be used to confirm this finding?
