Understanding Your Ejection Fraction: What Those Numbers Really Mean
If you've recently had an echocardiogram or other heart test, you may have seen a result that reads something like "LVEF: 55%" and wondered what this means. Many patients look at this number and think, "Oh no, my heart is only working at 55%!" But here's the good news: that's not what this number means at all.
Let's break down what ejection fraction actually measures and why understanding it correctly can give you a much clearer picture of your heart health.
Your Heart: A Remarkable Two-Phase Pump
To understand ejection fraction, we first need to think about how your heart works. Your heart is essentially a muscular pump that works in two main phases, like a rhythmic squeeze-and-release cycle that happens about 60 to 100 times every minute of your life.
The Filling Phase (Diastole): Think of your heart's main pumping chamber, the left ventricle, as a flexible balloon. During diastole, this chamber relaxes and expands, drawing blood in from your lungs through the left atrium. It's like slowly inflating a balloon with water instead of air. During this phase, your heart muscle is at rest, and the chamber fills with oxygen-rich blood that's ready to be pumped out to your entire body.
The Squeezing Phase (Systole): Now comes the powerful part. During systole, the muscular walls of your left ventricle contract forcefully, like squeezing that water-filled balloon. This contraction pushes blood out through your aorta to supply oxygen and nutrients to every organ and tissue in your body, from your brain to your toes.
What Ejection Fraction Actually Measures
Here's where it gets interesting, and where that common misunderstanding comes in. Ejection fraction doesn't measure how well your entire heart is working. Instead, it measures something much more specific: what percentage of blood that filled your left ventricle gets pumped out with each heartbeat.
Let's use a simple example. Imagine your left ventricle fills with 100 milliliters of blood during the filling phase. When it contracts, it doesn't push out every single drop of that blood—that would actually be impossible and isn't how healthy hearts work. Instead, a healthy heart typically pumps out about 50 to 70 milliliters of that 100 milliliters. The remaining 30 to 50 milliliters stays behind, ready to mix with the next incoming blood for the next heartbeat.
If your heart pumps out 55 milliliters out of that 100 milliliters, your ejection fraction is 55%. This means your heart is squeezing out 55% of the blood that filled the chamber—and that's completely normal and healthy.
What's Normal, and What Isn't?
Normal Ejection Fraction: A healthy ejection fraction typically ranges from 50% to 70%. If your ejection fraction is 55%, your heart is performing beautifully within the normal range. You're not missing 45% of your heart function—you have a heart that's working exactly as it should.
Mildly Reduced: An ejection fraction between 40% and 49% is considered mildly reduced. This might indicate some weakening of the heart muscle, but many people with ejection fractions in this range feel perfectly fine and live normal, active lives.
Moderately Reduced: An ejection fraction between 30% and 39% is moderately reduced and typically requires medical attention and treatment.
Severely Reduced: An ejection fraction below 30% is considered severely reduced and indicates significant heart muscle weakness that needs comprehensive medical management.
Why Might Ejection Fraction Be Low?
Understanding what can cause a reduced ejection fraction helps put the condition in perspective. The heart muscle itself might be weakened by several conditions:
Heart Attack Damage: When part of the heart muscle is damaged by a heart attack, that damaged area can't contract as effectively, reducing the overall squeezing power of the left ventricle.
Cardiomyopathy: This is a general term for diseases of the heart muscle itself. Sometimes the muscle becomes thick and stiff, sometimes it becomes thin and stretched out, and sometimes it becomes inflamed. Each of these changes can affect how well the heart can squeeze.
Long-term High Blood Pressure: When your heart has to work extra hard for years to pump against high blood pressure, the muscle can eventually become tired and less efficient, like any muscle that's been overworked.
Heart Valve Problems: If the valves that control blood flow in and out of the heart aren't working properly, the heart has to work harder and less efficiently.
Infections or Toxins: Sometimes infections, certain medications, alcohol, or other toxins can weaken the heart muscle.
The Bigger Picture: You're More Than One Number
While ejection fraction is an important measurement, it's just one piece of your heart health puzzle. Many people with reduced ejection fractions live full, active lives with proper medical care. Your doctor looks at your ejection fraction alongside your symptoms, other test results, your medical history, and how you feel day-to-day.
Some people with normal ejection fractions might still have heart problems, while others with reduced ejection fractions might feel great and have excellent quality of life with treatment. Your heart's ability to fill properly during the relaxation phase is just as important as how well it squeezes, and there are many other aspects of heart function that contribute to your overall cardiovascular health.
Moving Forward with Confidence
If you've been told you have a reduced ejection fraction, remember that this is a starting point for treatment, not a final verdict. Modern heart medications and treatments can often help improve heart function and, more importantly, help you feel better and live longer.
If your ejection fraction is normal, like that 55% we mentioned earlier, you can feel reassured that this aspect of your heart function is working well. Continue with heart-healthy habits like regular exercise, a balanced diet, not smoking, and managing stress.
The most important thing to remember is that an ejection fraction of 55% doesn't mean you have 55% heart function—it means your heart is doing exactly what a healthy heart should do, efficiently pumping more than half the blood it receives with every single beat, thousands of times every day, keeping you alive and thriving.
Your heart is an remarkable organ, and understanding how it works can help you feel more confident about your health and more prepared to have meaningful conversations with your healthcare team about keeping it strong for years to come.
