Ejection fraction is a measurement of how much blood your heart pumps out with each beat, expressed as a percentage. A normal ejection fraction falls between 50% and 70%, meaning your heart pushes out roughly half to two-thirds of the blood that fills it. Doctors use this number as one of the most important indicators of how well your heart is functioning.
How Ejection Fraction Works
Your heart fills with blood between beats, then contracts to push that blood out to the rest of your body. Ejection fraction measures the proportion of blood that actually gets pumped out during each contraction compared to the total amount that filled the chamber. If your left ventricle (the heart’s main pumping chamber) holds 100 milliliters of blood and squeezes out 60 milliliters, your ejection fraction is 60%.
A heart that pumps out 50% to 70% of its blood per beat is working normally. That might sound low, since nearly half the blood stays behind, but the heart is designed to work this way. It needs a reserve of blood in the chamber to maintain pressure and keep the pumping cycle going smoothly.
What the Numbers Mean
The American Heart Association and the 2022 clinical guidelines from the ACC break ejection fraction into four categories:
- Normal (preserved): 50% or higher. The heart is squeezing with adequate force. However, some people with a normal ejection fraction can still have heart failure if the heart muscle has become stiff and doesn’t fill properly between beats.
- Mildly reduced: 41% to 49%. The heart’s pumping ability is slightly below normal. This range often signals early trouble and may benefit from treatment.
- Reduced: 40% or lower. The heart is significantly weakened. This is the threshold that defines classic heart failure with reduced ejection fraction.
- Improved: previously 40% or lower, now above 40%. This category recognizes patients whose hearts have recovered some pumping strength with treatment. Even after improvement, continuing treatment is important because stopping can cause the number to drop again.
How It’s Measured
The most common way to measure ejection fraction is an echocardiogram, which uses ultrasound waves to create a moving image of your heart. It’s painless, takes about 30 to 60 minutes, and doesn’t involve radiation. A technician places a probe on your chest, and software estimates how much blood leaves the ventricle with each beat.
Other imaging methods can also measure it. A cardiac MRI provides the most precise measurement and is sometimes used when echocardiogram images aren’t clear enough. Nuclear stress tests, which involve injecting a small amount of radioactive tracer and taking images of blood flow through the heart, can estimate ejection fraction as well. During a cardiac catheterization, doctors can calculate it directly by injecting contrast dye into the ventricle.
Because different methods can produce slightly different numbers, your doctor will typically use the same type of test over time to track changes accurately.
Symptoms of a Low Ejection Fraction
When your heart can’t pump enough blood to meet your body’s demands, the earliest and most common symptom is shortness of breath during physical activity. You might notice that walking up stairs or carrying groceries leaves you more winded than it used to. Fatigue is equally common, a deep tiredness that doesn’t improve much with rest.
As ejection fraction drops further, symptoms become more noticeable. Fluid can back up into the lungs, causing shortness of breath even while lying flat or waking you from sleep gasping for air. Swelling in the ankles, legs, or abdomen develops when fluid accumulates in the body’s tissues. Some people experience a persistent dry cough, heart palpitations, or a general sense of weakness they can’t explain.
These symptoms overlap with many other conditions. Shortness of breath on exertion can come from lung disease, obesity, anemia, or simply aging. Ankle swelling is common with vein problems or kidney issues. That overlap is one reason ejection fraction is so valuable as an objective measurement: it gives a clear, numerical answer about whether the heart itself is the source of the problem.
What Causes Ejection Fraction to Drop
Coronary artery disease is the most common cause of a reduced ejection fraction. When the arteries supplying blood to the heart muscle narrow or become blocked, parts of the muscle can weaken or die, especially after a heart attack. The damaged areas no longer contract effectively, and the overall pumping percentage falls.
Other causes include dilated cardiomyopathy (where the heart chamber enlarges and weakens without blocked arteries), long-standing high blood pressure that forces the heart to work harder until it eventually wears out, damaged heart valves that create inefficient blood flow, viral infections that inflame the heart muscle, and chronic conditions like diabetes and obesity that strain the cardiovascular system over time. Persistent irregular heart rhythms can also gradually weaken the heart if left untreated. In some cases, a genetic predisposition plays a role.
Why a Low Number Is Serious
Ejection fraction is one of the strongest predictors of long-term outcomes in heart failure. In a study of 685 heart failure patients followed for a median of about two and a half years, those with an ejection fraction of 35% or lower had a five-year survival rate of 25%, compared to 46% for those in the 36% to 45% range. The lower the number, the higher the risk of the heart simply not being able to keep up with the body’s needs.
That said, ejection fraction is not the whole story. Two people with the same percentage can feel very different depending on what’s causing their heart failure, how their body compensates, and how they respond to treatment. Some people with an ejection fraction of 30% live active lives with proper medication, while others with higher numbers struggle with symptoms.
How to Improve Ejection Fraction
A low ejection fraction is not necessarily permanent. With the right combination of medication and lifestyle changes, many people see meaningful improvement.
Current guidelines recommend four core classes of medication for heart failure with reduced ejection fraction. These drugs work through different pathways to reduce the strain on the heart, prevent harmful remodeling of the heart muscle, and remove excess fluid. One of the newer additions to standard treatment is a class of drugs originally developed for diabetes that has shown significant benefits for heart failure patients regardless of whether they have diabetes. The specific medications and doses are tailored to each person based on their blood pressure, kidney function, and how they tolerate treatment.
Exercise makes a real difference. A large analysis pooling data from 13 trials with nearly 4,000 heart failure patients found that structured exercise programs improved both physical capacity and quality of life, with benefits persisting at 12 months. High-intensity interval training, in particular, has been shown to improve ejection fraction itself. The key is starting gradually and ideally participating in a supervised cardiac rehabilitation program, where exercise intensity is carefully matched to your current capacity.
Diet matters too. The DASH diet, which emphasizes fruits, vegetables, whole grains, and limited sodium, has been linked to fewer heart failure hospitalizations. A moderate approach to salt restriction appears more effective than extreme sodium cutoffs. For people with heart failure and obesity, combining exercise with calorie reduction has improved both exercise tolerance and quality of life in clinical trials.
Quitting smoking is linked to a lower incidence of serious cardiac events in heart failure patients. Limiting or eliminating alcohol is particularly important, since alcohol can directly damage heart muscle and worsen cardiomyopathy.
Heart Failure With a Normal Ejection Fraction
One of the more counterintuitive facts about ejection fraction is that you can have heart failure even when the number looks normal. This condition, called heart failure with preserved ejection fraction, accounts for roughly half of all heart failure cases. The heart squeezes adequately but has become stiff, so it doesn’t relax and fill properly between beats. The result is the same: fluid backs up, and the body doesn’t get enough blood flow.
This type of heart failure is more common in older adults, women, and people with high blood pressure or obesity. It has historically been harder to treat than heart failure with a reduced number, though newer medications are now showing benefit for this group as well. Diagnosing it requires more than just checking the ejection fraction. Doctors look for elevated levels of certain hormones released by stressed heart muscle and may use specialized imaging to assess how well the heart fills.