There are different types of heart failure. They are classified by which part of the heart is affected and characteristics including symptoms. The heart is a muscle that contracts and relaxes with every beat. With every beat, the heart pumps blood throughout the body allowing for movements.
Ejection fraction
Ejection fraction (EF) describes the pumping ability of the left side of the heart. It represents the percentage of blood pumped out of the heart each time it beats (contracts).1-2
The heart beats over 100,000 times a day and moves our blood thousands of times throughout our circulatory system. When a healthy heart beats it does not completely fill or empty each time. Ejection fraction is expressed as a percentage. The normal range is 55% to 70 %.3 When the amount of blood ejected becomes lower, it is considered heart failure.3
The heart works by pumping oxygen-rich blood from the left ventricle of the heart into the aorta where it travels throughout the body to provide nourishment. After traveling through the body, the oxygen-depleted blood returns to the heart into the right atrium. From there, it moves to the right ventricle and then into the lungs where the blood becomes oxygenated. It returns from the lungs into the left atrium and then is pumped back into the left ventricle to start the cycle all over again.4
Measurements
The ejection fraction is the main consideration in prescribing the most appropriate treatment for each individual. Monitoring the measurements also can help evaluate if the treatment is effective. Ejection fraction rates can vary; they can increase or decrease based on the type of heart condition and the effectiveness of prescribed treatment.3
Ejection fraction can be measured using different technologies or imaging methods. The most accurate tests include an echocardiogram, MRI, and nuclear medicine scan sometimes referred to as a nuclear stress test or a multiple gated acquisition (MUGA).3
The numbers
Ejection fraction from 55% to 70%
When the pumping ability of the heart is normal, between 55% and 70% of the blood is pushed out into the body by the left ventricle each time the heart contracts. Just because heart function appears normal based on the ejection fraction, it is still possible to have heart failure. This is called heart failure with preserved ejection fraction (HFpEF) or diastolic heart failure. This indicates that the left ventricle is still pumping normally but it can no longer relax properly or fill completely with blood because the muscle has become stiff. In addition to the EF measurements, the heart valves and heart muscle should be evaluated for stiffness to determine the severity of heart failure.3
40% to 54%
When the pumping ability of the left ventricle is slightly below normal, 40%- 54% of the blood is pushed out into the body each time the heart contracts. This means there is a decreased amount of blood being pushed out of the ventricles. This results in less oxygen-rich blood circulating to nourish the body. At this stage, there may be no physical symptoms experienced.3
35% to 39%
When the pumping ability of the heart is moderately below normal, 35%-39% of the blood is pushed out into the body each time the heart contracts. This is considered mild heart failure with a reduced ejection fraction.3 It is often referred to as HFrEF (heart failure with reduced ejection fraction) or systolic heart failure.5
Less than 35%
When the pumping ability of the heart is severely below normal, less than 35% of the blood is pushed out into the body each time the heart contracts. This is considered moderate-to-severe HFrEF. This can create life-threatening situations where the left ventricle fails to function properly. In some people, the right and left ventricles do not act in a coordinated manner, resulting in worsening symptoms and even death. Treatments can include medications and/or implanted devices to improve in the synchronized beating of the heart.3