Ejection Fraction

heart chamber and valves

When doctors want to assess your heart's function, they often turn to "ejection fraction." This measure compares the volume of blood held within a cardiac ventricle at the beginning of a heartbeat, to the volume of blood remaining after the ventricle finishes beating. In other words, it measures the proportion of blood that is actually ejected by a heart ventricle (most typically, the left ventricle) with each heartbeat. If the ventricle ejects 60% of the blood it holds at the beginning of each heartbeat, its ejection fraction is 60% (sometimes expressed as a decimal, such as 0.6).

The Purpose of Ejection Fraction

Ejection Fraction is useful as a measure of the overall strength of the heart. People who have had a heart attack, who have heart failure, coronary artery disease or an enlarged heart, might have their ejection fraction measured to determine how heart disease may be affecting their heart's function.

A doctor might also measure ejection fraction if a patient exhibits symptoms associated with poor heart function, such as:

  • Shortness of breath or inability to exercise
  • Swelling of the feet and lower legs
  • Fatigue and weakness
  • Rapid, forceful, uncomfortable or obviously irregular heart beat
  • Abdominal discomfort such as swelling, pain or nausea
  • Mental confusion

Typically, the left ventricle ejects 55% or more of its blood volume with each beat, so a "normal" ejection fraction is 55-70% An ejection fraction of 40-50% is considered “below normal.” People who have heart failure due to cardiomyopathy most often have ejection fractions that are less than 40%. The lower the ejection fraction, the weaker the heart muscle (since more cardiac dilation is required to maintain the cardiac stroke volume).

Doctors use the ejection fraction measurement to diagnose cardiomyopathy, to assess the effectiveness of medical therapy in stabilizing or improving heart failure, and to decide on the best treatment approaches for heart failure.

If the ejection fraction is falling with repeated testing, that generally means the heart muscle is becoming weaker. An increasing ejection fraction usually means heart muscle strength is improving.

Left vs. Right Ejection Fraction

It is important to note that when doctors say the words “ejection fraction” they are referring to the ejection fraction of the left ventricle. More properly this would be called the “left ventricular ejection fraction” or “LVEF” and you may sometimes see or hear this terminology.

The right ventricle also has its own ejection fraction (the “right ventricular ejection fraction,” or RVEF). However, the RVEF is rarely mentioned or talked about by doctors, partly because it is much more difficult to measure than the LVEF, and partly because knowing the precise RVEF is usually not particularly useful in making a clinical assessment of cardiac function.

So when your doctor says “ejection fraction,” he or she is referring to the LVEF.

Why Heart Disease Sometimes Causes a Reduced Ejection Fraction

When the heart muscle becomes weak, the muscle fibers become incapable of contracting fully. This means that, unless there is compensation for the poor muscle function, the volume of blood pumped with each heartbeat (the “ stroke volume ”) diminishes.

To compensate, the heart dilates—enlarges—allowing it to hold more blood. This dilation allows for a normal (or near-normal) stroke volume to be maintained, despite reduced muscle fiber shortening. Because of this dilation, while the proportion of blood being ejected during each heartbeat is diminished the stroke volume nonetheless tends to remain at a nearly normal level.

As an example, consider a person whose left ventricle holds 100 ccs of blood and has an ejection fraction of 50%. That person has a stroke volume of 50cc. If his ejection fraction were later to drop to 40%, his heart would tend to dilate enough to still allow for a 50cc stroke volume with each heartbeat—which would imply a dilation sufficient to hold 125 ccs. 

An enlarged heart is a compensatory mechanism that staves off symptoms of heart failure (by maintaining a normal cardiac output for as long as possible), but the fact that the heart is dilated indicates that the heart muscle is weakened.

Another name for the compensatory cardiac dilation that occurs with heart muscle disease is “remodeling.”

Tests that Measure Ejection Fraction

There are no risks or contraindications for measuring ejection fraction. The measurement can be assessed in several ways:

  • An echocardiogram, which is the most efficient way to monitor a person’s ejection fraction over time.
  • MUGA scan, which is the most accurate and reproducible method of measuring the ejection fraction. It is typically used in situations where repeated, precise measurements are needed; for instance, when chemotherapy is being used that can be toxic to the heart muscle---most commonly, doxorubicin (Adriamycin).
  • During cardiac catheterization, which is the most invasive way of measuring ejection fraction. The procedure involves inserting a catheter into blood vessels in the groin, wrist, neck or arm.

Interpreting Results

While a low ejection fraction rate usually signifies heart damage, it is still possible to have heart failure with a normal ejection fraction. Doctors refer to this as heart failure with preserved ejection fraction (HFpEF) or diastolic heart failure. This can occur if the heart muscle becomes thick or rigid, preventing the normal volume of blood from filling up ventricles. Though the heart may pump out blood at a normal rate, the amount of blood it pumps is still low.

On the other hand, a high ejection fraction of greater than 75% can also indicate a heart condition. It can be a sign of hypertrophic cardiomyopathy, which can affect people of all ages.This condition causes a thickening of the heart muscle and can lead to a cardiac arrest.

Wherever your ejection fraction falls on the scale, your doctor can advise you of the next steps to take to keep your heart healthy for as long as you can.

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Article Sources
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  1. https://www.heart.org/en/health-topics/heart-failure/diagnosing-heart-failure/ejection-fraction-heart-failure-measurement

  2. Luk A, Ahn E, Soor GS, Butany J. Dilated cardiomyopathy: a review. J Clin Pathol 2009; 62:219. DOI:10.1136/jcp.2008.060731

  3. Clarke CL, Grunwald GK, Allen LA, et al. Natural history of left ventricular ejection fraction in patients with heart failure. Circ Cardiovasc Qual Outcomes 2013; 6:680. DOI:10.1161/CIRCOUTCOMES.111.000045

  4. Malm S, Frigstad S, Sagberg E, Skjaerpe T. Accurate and reproducible measurement of left ventricular volume and ejection fraction by contrast echocardiography: a comparison with magnetic resonance imaging. J Am Coll Cardiol 2004; 44:1030. DOI:10.1016/j.jacc.2004.05.068

  5. https://www.aafp.org/afp/2017/1101/p582.html

Additional Reading
  • American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, et al. ACCF/ASE/AHA/ASNC/HFSA/HRS/SCAI/SCCM/SCCT/SCMR 2011 Appropriate Use Criteria for Echocardiography. A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, American Society of Echocardiography, American Heart Association, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance American College of Chest Physicians. J Am Soc Echocardiogr 2011; 24:229. doi: 10.1016/j.echo.2010.12.008.
  • Lang RM, Bierig M, Devereux RB, et al. Recommendations for Chamber Quantification: a Report From the American Society of Echocardiography's Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005; 18:1440.