Ejection fraction (EF) is a measurement of how much blood your heart
pushes out when it beats. This measurement helps with the diagnosis and
treatment of heart failure.
Your heart has four chambers. The top two, called the atria, take blood
in from the veins and lungs. The bottom two are called ventricles. When
your heart beats, the right ventricle pumps blood to your lungs and the
left ventricle pumps blood to your lungs and the rest of your body. Even
in a healthy heart, some blood stays behind in the ventricles. The EF is
the percentage of blood that is pumped out of a ventricle with each
EFs between 55 and 75 percent are considered normal for the left
ventricle, which is the main pumping chamber of the heart. In heart
failure caused by a weak heart muscle, the EF number can become very
small. An EF of 20 percent means 80 percent of the blood stays in the
ventricle and therefore the heart is not providing all the blood the
Doctors can use an echocardiogram, or other techniques such as cardiac
MRI or nuclear imaging, to measure EF and see how well your heart is
Although the EF is very important and is the most commonly used method
of expressing overall heart function, it is important to note that some
people have heart failure symptoms despite a normal-range EF. Also,
although a low EF is never normal, with treatment some people can lead a
fairly normal, active life despite a decreased EF.
For more information, call 1.866.CALL.MLH.