Overview

Heart failure with reduced ejection fraction (HFrEF) is a type of heart failure. It happens when the heart's lower left chamber (left ventricle) doesn't pump blood out to the body as well as it should.

It's sometimes called systolic heart failure. This is because your left ventricle doesn't squeeze forcefully enough during systole, which is the phase of your heartbeat when your heart pumps blood. So the amount of blood being pumped out is less than the body needs.

To see how much blood inside the left ventricle is pumped out with each contraction, the ejection fraction is measured. The left ventricle squeezes and pumps some (but not all) of the blood in the ventricle out to your body.

A normal ejection fraction is more than 55%. This means that more than 55% of the total blood in the left ventricle is pumped out with each heartbeat.

You may be diagnosed with HFrEF when the ejection fraction is 40% or less. You may be diagnosed with heart failure with a mildly reduced ejection fraction when the ejection fraction is between 41 and 49%. If heart failure treatment has increased the ejection fraction, it is called heart failure with improved ejection fraction.^{footnote 1}

What causes it?

There are many different problems that can cause heart failure with reduced ejection fraction. They include:

Coronary artery disease or heart attack.

They can limit or block blood flow in your coronary arteries, which bring blood to your heart muscle. This limited or blocked blood flow weakens or damages heart muscle and impairs the muscle's ability to pump.

Cardiomyopathy.

This is a disease of the heart muscle. The heart muscle is weakened, so it can't pump properly.

High blood pressure.

This causes elevated pressure in your arteries. The heart works harder to pump against increased pressure, which weakens the muscle.

Diabetes.

This condition results in high blood sugar. Over time, diabetes can lead to problems with the heart muscle.

Aortic stenosis.

This means that the opening of the aortic valve is narrowed, which impairs blood flow. The heart works harder to pump blood through the narrowed valve, weakening the muscle.

Mitral regurgitation.

This means that the mitral valve doesn't close properly. The increased blood volume stretches and weakens the heart muscle.

Viral myocarditis.

This is a viral infection of your heart muscle. The infection causes inflammation in the heart muscle, which affects the heart's ability to pump.

Arrhythmia.

This is an irregular heart rhythm. The irregular rhythm reduces the pumping effectiveness of the heart.