The Most Misunderstood Heart Number (Plus Your Tune-Up Checklist)

Since February is Heart Health Month, it’s the perfect time to pull back the curtain on one of the most important metrics we use in cardiology: ejection fraction (EF).

The Star of the Show: The Left Ventricle

While your heart has four chambers, the heavy lifter is the left ventricle. This muscular chamber is responsible for pumping oxygen-rich blood to your entire body.  When we talk about how well your heart is "squeezing," we are almost always talking about the left ventricle.

What Exactly Is Ejection Fraction?

We measure heart function using an echocardiogram, which is simply an ultrasound of the heart. This test allows us to calculate your ejection fraction (EF) - the percentage of blood the heart pumps out with every heart beat.

Although other tests can assess EF (such as a cardiac MRI), it is most commonly measured via heart ultrasound.  And around 10 million of these procedures are performed in the US each year.  As a side note, simply listening to your heart with a stethoscope is not a reliable way to determine EF. In addition, checking your ejection fraction is not routine.  Meaning, something else has to trigger this evaluation (like an abnormal EKG or a heart murmur or a symptom that could be heart related - like new shortness of breath or palpitations or fatigue).  

A common misconception is that EF represents a "grade" out of 100 percent. Patients often see a result of 55 percent and worry they are "missing" 45 percent of their function. That is not how it works.  A healthy heart never empties completely. It only squeezes out a portion of its contents each time it beats.

Here is how we categorize EF numbers:

• 50% - 70%: Normal

• 40% - 49%: Mildly Reduced

• 30% - 39%: Moderately Reduced

• Below 30%: Markedly Reduced

So if your EF is 45 percent, for example, you are not at half-capacity. You are only about 5 percent below the normal range. Still abnormal, but only slightly so.

Why Does EF Drop?

EF typically declines when the heart muscle becomes damaged or scarred. Common causes include:

• Heart attacks - the most frequent cause of permanent muscle damage

• Viral infections - certain viruses can inflame the heart muscle (myocarditis)

• Valve disease - severe valve problems can overwork the muscle until it weakens

• Chemotherapy - some cancer treatments are cardiotoxic, which is why oncology patients often require regular heart ultrasounds

• Pregnancy - in very rare cases, EF can drop during or after pregnancy (peripartum cardiomyopathy)

• Alcohol - regular heavy intake can lead to EF reductions because alcohol is toxic to heart muscle (another good reason to limit our intakes) 

Can a Low EF Be Fixed?

The answer is: sometimes.

If the cause is alcohol, a viral infection or a valve problem, the heart can often recover once the underlying issue is addressed. Unfortunately, damage from a heart attack (the most common cause of low EF) is usually permanent.  This is why avoding a heart attack is your best insurance policy against experiencing reduced heart function.  As with all things heart, the best offense is a great defense.

Your Heart Tune-Up Checklist

Your heart is designed to last 100+ years, but it is not a set-it-and-forget-it machine.

To keep your left ventricle pumping in that 50 to 70 percent sweet spot:

1. Move daily. Regular exercise is essential for maintaining muscle tone.

2. Watch the fuel. Eat for health, not for disease. Step One Foods to the rescue!

3. Check your stats. High blood pressure, cholesterol, and blood sugar are silent heart artery stressors that can trigger a heart attack out of the blue. Normalize them through lifestyle first, and medication if necessary.

4. If you smoke, quit. This remains the single best thing you can do for your vascular health.

Finally, I encourage you to think of February as not just Heart Health Month, but as Heart Tune-Up Month. If you have not had a check up and your heart vitals assessed recently, now is the time to get going.