What Is Ejection Fraction?

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, it pumps blood out of the ventricles 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 heartbeat.

EFs between 55 and 75 percent are considered normal. 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 body needs.

Doctors can use an echocardiogram to measure EF and see how well your heart is working.