Understanding Heart Failure: What Is Ejection Fraction?

This measurement helps determine how well your heart is pumping.

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Your heart has an important job: In a nutshell, it works with your lungs to load your blood with oxygen, then pumps that oxygen-rich blood throughout your body to feed your organs.

Heart failure occurs when the heart muscle has become weak and can’t pump blood well enough to meet the body’s needs. Basically, it can’t keep up with its workload. “Heart failure is a condition where either your heart doesn’t pump well, or your heart doesn’t relax well,” says Michelle W. Bloom, MD, a cardiologist at Stony Brook University Medical Center.

“Ejection fraction is one of many numbers and many parameters that we use to measure how well or how poorly a person is doing with heart failure,” says Dr. Bloom.

What Is Ejection Fraction? 

To understand ejection fraction, it’s important to learn how blood pumps through the heart. A heart has four chambers: a right atrium and ventricle, and a left atrium and ventricle. In a normally functioning heart, blood gets returned from the body to the right atrium. It gets filtered through the right ventricle, then pumped to the lungs where it gets oxygenated. The blood then gets returned to the left atrium, and then passes through the left ventricle.

“The left ventricle is the main pumping chamber of the heart, and that blood leaves the left ventricle to be pumped out the aorta to the rest of the body,” says Dr. Bloom. “Ejection fraction is the percentage of blood that leaves the left ventricle—or the main pumping chamber—with every beat.”

Preserved vs. Reduced Ejection Fraction

In someone with heart failure, the quality of ejection fraction helps doctors determine what kind of heart failure you have. Ejection fraction is scored by measuring the amount of blood pumped out divided by the amount of blood in the chamber.

“Even in the strongest of hearts, not 100 percent of the blood leaves the heart with every contraction,” says Dr. Bloom. “So somewhere around 55 to 60 percent ejection fraction is what we consider to be a normal amount of blood that’s leaving the heart with every beat.”

In someone with heart failure, their ejection fraction measurement may be lower, meaning not as much blood is leaving with every contracting beat of the heart, says Dr. Bloom. This is called systolic heart failure, or heart failure with reduced ejection fraction. “Reduced ejection fraction means the heart muscle is weak, or maybe it’s dilated, it’s bigger than it should be,” says Dr. Bloom.

The other type of heart failure is called diastolic heart failure, or heart failure with preserved ejection fraction. “Around 50 percent of heart patients have preserved ejection fraction, meaning the heart muscle is actually quite strong, but it’s stiff and it doesn’t relax well,” says Dr. Bloom. “Their ejection fraction is preserved, meaning that it can be normal or even higher than normal, but the heart doesn’t fill properly, and that can limit the amount of blood supply to the rest of the body.”

In either scenario, the pressures in the heart circuit rise, which causes people to have symptoms such as shortness of breath and water retention. Learn more about the symptoms of heart failure.

Thanks to treatment options for heart failure, it is possible to improve your ejection fraction. A combination of lifestyle changes—managing weight, reducing salt intake, and exercising—and medications for heart failure may increase your ejection fraction, which can help you feel better.