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Heart failure, also known as congestive heart failure or chronic heart failure, occurs when the heart cannot pump blood properly. If you have heart failure, you may have heard your doctor mention ejection fraction — a way of measuring how effectively your heart pumps blood. This article will explain what ejection fraction is and why it matters if you have heart failure.
Heart failure means that the heart is not pumping blood efficiently and can’t keep up with the body’s needs. Heart failure does not mean that the heart has stopped functioning (cardiac arrest) or will stop at any moment. However, heart failure is a serious, chronic condition that must be managed.
Symptoms of heart failure may include:
If your doctor suspects heart failure based on your symptoms and other health factors, they may order tests to measure your heart’s ejection fraction.
The heart pumps blood by contracting (squeezing) and relaxing. When the heart contracts, blood is ejected — pumped out — from the heart’s two lower chambers, known as ventricles. When the heart relaxes, the ventricles refill with blood.
Ejection fraction indicates how much oxygen-rich blood leaves the heart each time it contracts. EF is a measurement — it has no signs or symptoms — and is expressed as a percentage.
Since the left ventricle is the heart’s main pumping chamber, ejection fraction typically refers only to the left ventricle, a measurement also known as left ventricular ejection fraction (LVEF).
Right ventricular ejection fraction is measured in people with right-sided heart failure, but this condition is not as common as left-sided heart failure.
The American Heart Association provides the following guidelines for ejection fraction.
The normal range for ejection fraction falls between 50 percent and 70 percent. It’s possible to have a normal EF measurement and still have heart failure. This is known as heart failure with preserved ejection fraction (HFpEF).
An EF below 40 percent is considered low. This may show that a person has heart failure with reduced ejection fraction (HFrEF) or cardiomyopathy — an enlarged, thick, or stiff heart muscle.
A lower EF means that the heart’s pumping action is weaker. This also indicates that the person is at higher risk of life-threatening complications, such as cardiac arrest, which occurs when the heart malfunctions and suddenly stops beating.
An ejection fraction between 41 percent and 49 percent may be considered borderline or midrange. A midrange EF does not always suggest heart failure but may be a sign of damage, such as from a previous heart attack.
Anything above 75 percent is considered a high ejection fraction. This may mean the person has a heart condition such as hypertrophic cardiomyopathy, a genetic condition that causes the walls of the left ventricle to be thicker than normal. A high EF may also be present when there is a heart valve leak (such as mitral valve regurgitation) and all the blood is not flowing in the correct direction.
There are two main types of left-sided heart failure, defined by the measured LVEF, and a possible third category.
Heart failure with preserved ejection fraction is also known as diastolic heart failure. In HFpEF, the heart muscle can contract normally, but the ventricles are thicker and stiffer than they should be. As a result, they don’t relax properly, so they don’t properly fill up with blood. Less blood in the ventricles means the heart pumps out less blood when it contracts.
Heart failure with reduced ejection fraction is also known as systolic heart failure. In HFrEF, the heart muscle is unable to contract completely and effectively, so less oxygen-rich blood is pumped to the rest of the body.
A new category called heart failure with midrange ejection fraction (HFmrEF) is still under investigation. HFmrEF often includes heart muscle that has been damaged or scarred by earlier heart attacks.
To measure ejection fraction, your doctor may recommend one or more of the following tests.
Also called echocardiography or echo, an echocardiogram is the most common method of measuring ejection fraction. This procedure uses sound waves to take pictures of the heart and attached blood vessels.
The multigated acquisition (MUGA) scan — also called radionuclide ventriculography or radionuclide angiography — measures how well the heart pumps with every beat. A radioactive tracer, called a radionuclide, is given intravenously and binds to red blood cells, and a special camera takes pictures of the heart at specific times during each heartbeat.
During a cardiac CT scan, X-rays produce images of the heart.
An MRI scan to study the heart is called a cardiovascular MRI. This procedure involves a magnetic field and radio waves to produce images of the heart.
During cardiac catheterization, a thin, hollow tube called a catheter is inserted into a large blood vessel in the arm or leg and gently guided to the heart. Images taken during this procedure can measure ejection fraction.
Also known as myocardial perfusion imaging, a nuclear stress test shows how well blood flows through (perfuses) the heart muscle. It reveals areas of the heart that aren’t getting enough blood flow, as well as how well the heart is pumping.
Nuclear stress tests involve injecting radioactive materials, or tracers, that mix with blood and are absorbed by the heart muscle as blood flows through the arteries. A special camera takes pictures of the heart to show how well the heart muscle is supplied with blood. The procedure is similar to a MUGA scan but tests different areas of the heart.
A variety of treatment options available have been scientifically shown to benefit people who have heart failure with reduced ejection fraction. These therapies — including medications, lifestyle changes, and surgery — can relieve symptoms, prevent complications, slow the worsening of heart failure, decrease hospitalizations, and perhaps prolong life.
Medications used in heart failure with reduced EF have not demonstrated the same benefits in heart failure with preserved EF. In clinical trials, it’s not clear which of the medications used for HFpEF are the most beneficial.
In practice, people with HFpEF are often prescribed the same medications as those used by people with HFrEF, although the scientific evidence for doing so is neutral. There are different options in HFpEF, depending on the reason for the heart failure. Be sure to discuss these treatments with your doctor.
Be sure to talk with your doctor if you are concerned about heart failure or how to treat it. Download these questions to ask your doctor to start the conversation.
A cardiologist can develop a treatment plan to improve your ejection fraction and relieve symptoms of heart failure.
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Larry A. Weinrauch, MD, FACC, FACP, FAHA
is an assistant professor of medicine at Harvard Medical School with a focus on cardiovascular disease and clinical outcomes research. Review provided by VeriMed Healthcare Network.
Learn more about him here.
Jane Chung, PharmD, RPh
earned a Bachelor of Science in Pharmacy Studies and a Doctor of Pharmacy from Northeastern University in Boston, MA.
Learn more about her here.
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