ADRIAN FLORIDO, HOST:
President Trump has the cardiac age of a 65-year-old. That's 14 years younger than his biological age. That is, at least, the assessment of the president's doctor following a medical evaluation earlier this month. But what does this actually mean? How is a cardiac age calculated? NPR's Allison Aubrey gets to the heart of the matter.
ALLISON AUBREY, BYLINE: We all know our age based on our date of birth. If you've got 80 candles on your birthday cake this year, one for each year, your chronological age is 80. But scientists have another way to estimate age known as biological age, which is your rate of aging compared to your peers. Cardiologist Doug Vaughan of Northwestern University says your cardiac age is a measure of your heart health.
DOUG VAUGHAN: We have better measures of cardiovascular age these days. And so if, let's say, you're 80 and your risk comes out that of a 67-year-old, then you would say, well, my cardiovascular age, so to speak, is 13 years younger.
AUBREY: One way to estimate cardiac age is by using an electrocardiogram, or EKG, which is a quick and painless test that records the electrical activity of the heart. If you've ever had one, you may remember electrodes are placed on your chest, explains Dr. Luke Laffin, a cardiologist at the Cleveland Clinic.
LUKE LAFFIN: It's a short, 10-second electrical snapshot. It gives us a lot of information about the heart rhythm but also can tell us if someone is in the midst of a current heart attack or if there are changes in the size of the chambers of the heart.
AUBREY: The results are displayed as a series of waves and squiggles on a graph. And doctors know how to look at these graphs to spot obvious signs of trouble. This certainly isn't new. The EKG is more than a hundred years old. But what is new is how the results can be used to estimate cardiac age using AI and machine learning. Laffin says using data from millions of EKGs, computers can hash through trillions of bits of information.
LAFFIN: So you get all these ECGs. You put them into this machine learning algorithm for AI. And then it's able to pick up subtle features, patterns that wouldn't be recognizable for us.
AUBREY: The AI models have been developed to detect patterns that cardiologists could never spot with a naked eye, and by studying millions of them, they've identified tiny changes that correlate with disease risk and age.
VAUGHAN: So I'm a cardiologist. I can read the electrocardiogram. I can't tell your age. I have no clue what your age is based on how we learn how to read an electrocardiogram. But this tool does things that the human eyes can't do.
AUBREY: The important thing to know is that this is not a precise or definitive estimate. Dr. Vaughan says cardiologists have lots of existing tools, including stress tests and coronary artery calcium scores and many other measures that also predict risk of heart disease.
VAUGHAN: It includes your blood pressure, your cholesterol level, whether or not you have diabetes, whether or not you smoke.
AUBREY: In the era of AI, there's intrigue because the idea of a cardiac age is new. And Vaughan says there are multiple AI models now being tested to validate their accuracy, so it's still early days. But one day, this may be routine.
VAUGHAN: I think that's where we're headed. You know, the next wave of preventive medicine involves measuring biological age at an earlier point in time, you know, maybe in your 20s.
AUBREY: Spotting signs of trouble early in life creates more opportunities to intervene to prevent heart disease.
Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.
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