Two hearts overlapping each other. One has more blood and the other is a darker color and has a lower blood level, heart condition, heart failure, Reduced Ejection Fraction

What Is Reduced Ejection Fraction?

Reviewed by: HU Medical Review Board | Last reviewed: October 2019

Ejection fraction (EF) measures the percentage of blood pumped out of the left ventricle of the heart each time it beats. The heart muscle contracts and relaxes with every beat. Each time this happens the heart pumps blood throughout the body. This is the fundamental process of circulation. A normal heart does not completely fill or empty each time it beats. The ejection fraction is expressed as a percentage where the normal range is 55% to 70%.1

There are 2 classifications of ejection fraction in heart failure (HF). Heart Failure where the ejection fraction is preserved (diastolic heart failure) and heart failure where the ejection fraction is reduced (systolic heart failure).1

Systolic heart failure

Also known as heart failure with reduced ejection fraction (HFrEF), systolic heart failure develops when the left ventricle fails to contract normally. The heart no longer pumps with the force needed to eject enough blood into circulation.2 It is different from diastolic heart failure where the left ventricle still pumps properly.1-2

Systole is the phase of the heartbeat when the muscle contracts and pumps blood out of the heart’s chambers into the arteries. In systolic heart failure, the left ventricle doesn't contract or squeeze forcefully enough. As this condition progresses, the ventricle (which is the lower-left chamber of the heart) increases in size and cannot squeeze hard enough to pump the right amount of oxygen-rich blood out to fuel the body.1

What is too low?

Ejection fractions are grouped by the percentage of blood volume pumped out from the heart.2 An EF from 41 to 49 may be considered “borderline.” EF is not always an indication of heart failure. For example, it can reflect prior damage from a previous heart attack. As the severity of HF increases, the ejection fraction can get lower. An EF measurement under 40% is generally considered evidence of heart failure and at 35% or lower there is a high risk of developing dangerous changes in heart rhythm (arrhythmia) that can cause sudden cardiac arrest or death.3


HFrEF can have a number of different causes including conditions that affect the heart like high blood pressure, abnormal heart rhythms, coronary artery disease, and congenital birth defects. It can also be related to alcohol and drug abuse, chronic medical conditions like diabetes and HIV, or sleep apnea.4


Symptoms of heart failure in a patient with reduced ejection fraction include:1

  • Fatigue and weakness
  • Feeling of fullness or bloating
  • Chest pain, pressure or heart palpitations
  • Loss of appetite and nausea
  • Reduced ability to exercise comfortably
  • Shortness of breath
  • Swelling

Diagnosing HFrEF

In addition to a physical exam and complete medical history, blood tests and imaging tests are generally used in the diagnosis of people with reduced ejection fraction. There are multiple tests that can measure the ejection fraction of the left ventricle. These include cardiac catheterization, nuclear imaging, echocardiogram, CT scans, and MRIs.3

Treating HFrEF

Lifestyle changes are typically recommended for most heart conditions. Increasing physical activity, achieving a healthy weight, not smoking, and dietary changes like reducing salt and excess fluids can all be effective measures.4 Treatment includes prescription medications to help improve heart function and control symptoms. There are also medical devices that can help control the coordination of the heart’s chambers as they beat so as to maintain a healthy rhythm.4

The outcome of treatment for HFrEF varies from person to person. It is dependent on the cause and severity of HF as well as other comorbidities, the other illnesses present. Medication and lifestyle changes can result in an improvement, but others may face life-threatening challenges requiring surgical intervention to control symptoms and prevent or delay further progression of heart failure.5

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