Causes of heart failure with reduced ejection fraction

Left-sided heart failure

The heart's pumping action moves oxygen-rich blood as it travels from the lungs to the left atrium, then on to the left ventricle, which pumps it to the rest of the body. The left ventricle supplies most of the heart's pumping power, so it's larger than the other chambers and essential for normal function. In left-sided or left ventricular (LV) heart failure, the left side of the heart must work harder to pump the same amount of blood.

There are two types of left-sided heart failure. Drug treatments are different for the two types.

• Heart failure with reduced ejection fraction (HFrEF), also called systolic failure: The left ventricle loses its ability to contract normally. The heart can't pump with enough force to push enough blood into circulation.
• Heart failure with preserved ejection fraction (HFpEF), also called diastolic failure (or diastolic dysfunction): The left ventricle loses its ability to relax normally (because the muscle has become stiff). The heart can't properly fill with blood during the resting period between each beat.

Right-sided heart failure

The heart's pumping action moves "used" blood that returns to the heart through the veins through the right atrium into the right ventricle. The right ventricle then pumps the blood back out of the heart into the lungs to be replenished with oxygen.

Right-sided or right ventricular (RV) heart failure usually occurs as a result of left-sided failure. When the left ventricle fails, increased fluid pressure is, in effect, transferred back through the lungs, ultimately damaging the heart's right side. When the right side loses pumping power, blood backs up in the body's veins. This usually causes swelling or congestion in the legs, ankles and swelling within the abdomen such as the GI tract and liver (causing ascites).

Congestive heart failure

Congestive heart failure (CHF) is a type of heart failure which requires seeking timely medical attention, although sometimes the two terms are used interchangeably.

As blood flow out of the heart slows, blood returning to the heart through the veins backs up, causing congestion in the body's tissues. Often swelling (edema) results. Most often there's swelling in the legs and ankles, but it can happen in other parts of the body, too.

Sometimes fluid collects in the lungs and interferes with breathing, causing shortness of breath, especially when a person is lying down. This is called pulmonary edema and if left untreated can cause respiratory distress.

Heart failure also affects the kidneys' ability to dispose of sodium and water. This retained water also increases swelling in the body's tissues (edema).

Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.

Ejection Fraction Measurement and Heart Failure

What is “ejection fraction”?

Ejection fraction (EF) is a measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction. An ejection fraction of 60 percent means that 60 percent of the total amount of blood in the left ventricle is pushed out with each heartbeat.

This indication of how well your heart is pumping out blood can help to diagnose and track heart failure.

What’s normal?

• A normal heart’s ejection fraction may be between 50 and 70 percent.
• You can have a normal ejection fraction measurement and still have heart failure (called HFpEF or heart failure with preserved ejection fraction).
• If the heart muscle has become so thick and stiff that the ventricle holds a smaller than usual volume of blood, it might still seem to pump out a normal percentage of the blood that enters it. In reality, though, the total amount of blood pumped isn’t enough to meet your body’s needs.

What’s too low?

• An ejection fraction measurement under 40 percent may be evidence of heart failure or cardiomyopathy.
• An EF from 41 to 49 percent may be considered “borderline.” It does not always indicate that a person is developing heart failure. Instead, it may indicate damage, perhaps from a previous heart attack.
• In severe cases, ejection fraction can be very low.
• Learn ways to improve your low ejection fraction.

What’s too high?

An ejection fraction measurement higher than 75 percent may indicate a heart condition such as hypertrophic cardiomyopathy.  

Download HF And Your Ejection Fraction Explained English (PDF) | Spanish (PDF)

Using ejection fraction in diagnosis

When examined using an echocardiogram, a significant number of patients with heart failure are revealed to have normal ventricular ejection fraction. This condition was previously called diastolic heart failure; it’s now referred to as heart failure with preserved ejection fraction.

Your doctor may mention one of these two EF-related scenarios:

1. Preserved ejection fraction (HFpEF) – also referred to as diastolic heart failure. The heart muscle contracts normally but the ventricles do not relax as they should during ventricular filling (or when the ventricles relax).
2. Reduced ejection fraction (HFrEF) – also referred to as systolic heart failure. The heart muscle does not contract effectively, and therefore less oxygen-rich blood is pumped out to the body.

Tests for measuring EF

Your doctor may recommend one or more of these tests to measure your ejection fraction:

• Echocardiogram (or “echo”) - the most widely used test
• MUGA scan
• CAT scan
• Cardiac catheterization
• Nuclear stress test

Learn more about common tests for diagnosing heart failure.

Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.

What causes reduction in ejection fraction?

How common is heart failure with reduced ejection fraction?

Can you have reduced ejection fraction without heart failure?