Topic Overview

Heart failure with preserved ejection fraction (HFpEF) occurs when the lower left chamber (left ventricle) is not able to fill properly with blood during the diastolic (filling) phase. The amount of blood pumped out to the body is less than normal.

It is also called diastolic heart failure.

What does preserved ejection fraction mean?

The types of heart failure are based on a measurement called the ejection fraction. The ejection fraction measures how much blood inside the ventricle is pumped out with each contraction. 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 55% of the total blood in the left ventricle is pumped out with each heartbeat.

Heart failure with preserved ejection fraction (HFpEF) happens when the left ventricle is not filling with blood as well as normal. The ventricle can pump well. But it may be stiff so it cannot relax and fill with blood as well as normal. The ejection fraction is 50% or more. HFpEF may also be diagnosed if the ejection fraction is 40% to 49%.^{footnote 1}

Although the ejection fraction may be normal, the heart has less blood inside it to pump out. So the heart pumps out less blood than the body needs.

Examples of ejection fractions of a healthy heart and a heart with preserved ejection fraction:

• A healthy heart with a total blood volume of 100 mL that pumps 60 mL has an ejection fraction of 60%.
• A heart with a stiff left ventricle that has a total blood volume of 90 mL and pumps 50 mL has an ejection fraction of 55%.

HFpEF happens because the left ventricle’s muscle becomes too stiff or thickened. To compensate for stiff heart muscle, your heart has to increase the pressure inside the ventricle to properly fill the ventricle. Over time, this increased filling causes blood to build up inside the left atrium and eventually into the lungs, which leads to fluid congestion and the symptoms of heart failure.

What causes it?

The most common cause of diastolic heart failure is the natural effect of aging on the heart. As you age, your heart muscle tends to stiffen, which can prevent your heart from filling with blood properly, leading to diastolic heart failure.

But there are many health problems that can impair your left ventricle’s ability to fill properly with blood during diastole.