Heart ejection fraction is the percentage of blood your heart pumps out with each beat. Specifically, it measures how much blood the left ventricle (the heart’s main pumping chamber) ejects during each contraction. A normal ejection fraction falls between 50% and 70%, meaning roughly half to two-thirds of the blood in the chamber gets pushed out with every heartbeat. If your doctor has mentioned this number, it’s one of the most important measures of how well your heart is working.
How Ejection Fraction Is Calculated
The math behind ejection fraction is straightforward. Your left ventricle fills with blood between beats, then squeezes to push blood out to the rest of your body. Ejection fraction is simply the amount pumped out divided by the total amount that was in the chamber, multiplied by 100 to give a percentage.
So if your ventricle holds 100 milliliters of blood after filling and pumps out 65 milliliters with each beat, your ejection fraction is 65%. That’s a healthy number. The measurement reflects how efficiently your heart muscle contracts. A lower percentage means the heart isn’t squeezing forcefully enough to move an adequate volume of blood, which can leave your organs and tissues short on oxygen.
What the Numbers Mean
Ejection fraction results typically fall into a few clinically meaningful ranges:
- 50% or higher: Normal. The heart is pumping well.
- 41% to 49%: Mildly reduced. The heart is pumping slightly below normal, and your doctor will likely monitor it closely or investigate the cause.
- 40% or lower: Reduced. This is the threshold where heart failure with reduced ejection fraction is diagnosed. The heart muscle is significantly weakened.
An ejection fraction of 60% means that 60% of the blood in the left ventricle gets pushed out with each heartbeat. The remaining 40% stays behind, which is completely normal. Your heart is never supposed to empty entirely.
It’s worth noting that an ejection fraction above 50% doesn’t guarantee everything is fine. Some people develop heart failure with preserved ejection fraction, where the number looks normal but the heart muscle has become stiff and can’t relax properly to fill with enough blood. The percentage pumped out is adequate, but the total volume of blood moving through the heart each beat is too low.
How It’s Measured
The most common way to measure ejection fraction is an echocardiogram, an ultrasound of the heart. It’s noninvasive, widely available, and doesn’t expose you to radiation. A technician places a probe on your chest, and sound waves create a moving image of your heart that shows the chambers contracting and relaxing in real time.
Cardiac MRI is considered the gold standard for accuracy and is sometimes used when echocardiogram images aren’t clear enough or when precise measurements matter for treatment decisions. A third option, called a MUGA scan, uses a small amount of radioactive tracer to track blood flow through the heart. MUGA scans were once widely used, but recent international guidelines now recommend them only as a backup when echocardiography or cardiac MRI isn’t available. Research has shown that MUGA scans can miss a significant number of cases where heart function has declined, failing to detect drops in ejection fraction in up to 28% of patients in one study.
One practical detail: your ejection fraction can vary somewhat between tests and between different imaging methods. A few percentage points of variation is normal and doesn’t necessarily mean your heart function has changed. For this reason, cardiologists prefer to track your ejection fraction using the same type of test each time rather than switching between methods.
Heart Failure Classifications by EF
Doctors classify heart failure into three categories based on ejection fraction, and the distinction matters because each type responds to different treatments.
Heart failure with reduced ejection fraction (sometimes abbreviated HFrEF) involves an EF of 40% or below. The heart muscle is weak and can’t contract with enough force. This is the type most people picture when they think of heart failure, and it has the most well-studied treatment options.
Heart failure with mildly reduced ejection fraction is a newer category, covering EF between 41% and 49%. It sits in a gray zone where the heart isn’t pumping normally but hasn’t dropped into the clearly reduced range. Research into the best treatments for this group is still evolving.
Heart failure with preserved ejection fraction involves an EF of 50% or higher. The pumping strength looks adequate on paper, but the heart is stiff and doesn’t fill properly. This type is more common in older adults and people with high blood pressure, obesity, or diabetes. It can be harder to treat because many of the medications that work well for reduced EF haven’t shown the same benefits here.
Symptoms of Low Ejection Fraction
When ejection fraction drops, your body doesn’t get the blood flow it needs. The most common symptoms include shortness of breath (especially during physical activity or when lying flat), persistent fatigue that doesn’t improve with rest, and swelling in the ankles, feet, or legs from fluid buildup. Some people notice a rapid or irregular heartbeat, dizziness, or a persistent cough.
The severity of symptoms doesn’t always match the EF number perfectly. Some people with an EF of 35% feel relatively functional, while others with an EF of 45% feel miserable. This has to do with how quickly the decline happened, whether the body has had time to compensate, and what’s causing the problem in the first place.
What Can Improve Ejection Fraction
A low ejection fraction isn’t always permanent. Depending on the cause, it can sometimes improve significantly with treatment. If the underlying issue is a blocked coronary artery, for example, restoring blood flow can allow the heart muscle to recover. If the cause is uncontrolled high blood pressure, bringing it under control reduces the strain on the heart and can lead to improvement over months.
Medications play a central role. For people with reduced ejection fraction, first-line treatments typically include drugs that lower the heart’s workload and help it pump more effectively, along with medications that block stress hormones from worsening heart failure. Some newer medications originally developed for diabetes have also shown clear benefits, lowering the risk of hospitalization. Your doctor will usually start with one or two medications and adjust over time based on how your heart responds.
Lifestyle changes make a measurable difference as well. Regular moderate exercise (guided by your care team), reducing sodium intake, managing fluid consumption, maintaining a healthy weight, and quitting smoking all support heart function. Cardiac rehabilitation programs, which combine supervised exercise with education, are one of the most effective interventions for people with heart failure.
Right Ventricular Ejection Fraction
Most of the time, “ejection fraction” refers to the left ventricle because it does the heavy lifting of pumping blood to the entire body. But the right ventricle, which sends blood to the lungs, has its own ejection fraction that matters more than doctors once appreciated.
The normal right ventricular ejection fraction averages around 54%, similar to the left side. A large study published in Circulation: Cardiovascular Imaging found that right ventricular EF is a powerful independent predictor of serious cardiac events. Patients with a right ventricular EF below 40% had a threefold increased risk of major cardiac events compared to those above that threshold, with a one-year event rate of 22% versus 7%. Each 10% drop in right ventricular EF was associated with a 1.3-fold increase in risk, even after accounting for left ventricular function.
Right ventricular EF isn’t routinely measured on a standard echocardiogram, but cardiac MRI can assess it accurately. It’s most relevant for people with pulmonary hypertension, right-sided heart failure, or certain congenital heart conditions.