Why the guidelines have changed

Roughly a quarter of adults aged 40 and older report taking a low-dose aspirin every day. “A lot of people think of aspirin almost like a vitamin,” says Amit Khera, director of preventive cardiology at the University of Texas Southwestern Medical Center. “But it’s a medicine with both benefits and side effects.” Here’s what you need to know about aspirin and your heart.

“When it comes to taking aspirin to prevent a first heart attack or stroke, we used to say ‘generally yes, occasionally no,’” says cardiologist Amit Khera.

“We thought that if your risk of having a first heart attack or stroke was a bit higher than average, aspirin was a good choice to prevent those events. But now, it’s not that simple.”

Today, the message on aspirin is “generally no, occasionally yes,” which echoes advice from the American Heart Association and draft guidelines from the U.S. Preventive Services Task Force.

The draft guidelines recommend that people 60 and older not start taking aspirin to prevent a first heart attack or stroke, while 40-to-59-year-olds who are at high risk should discuss the pros and cons of taking aspirin with their doctor.

What led to the flip?

“In 2018, three big trials showed that aspirin either modestly lowered—or had no effect on—the risk of having a first heart attack or stroke,” Khera explains. (Bayer funded one of the trials and weighed in on the design of another.)

woman having chest pains
Should you take aspirin to prevent a first heart attack or stroke? “Generally no, occasionally yes,” suggest new guidelines.
Dragana Gordic - stock.adobe.com.

And when researchers looked at data on roughly 164,000 people in those three trials plus 10 others, taking aspirin every day lowered the risk of a heart attack or stroke by a modest 11 percent. (All but two of the 13 trials used low-dose aspirin—between 50 and 100 milligrams. A regular aspirin is 325 mg.)

“So aspirin still works,” says Khera. “But maybe in the modern era where people are smoking less and risk factors like cholesterol and blood pressure are better controlled, there may be a little less utility for aspirin than in the past.”

That’s not what changed the guidelines, though.

The risks of aspirin

“We’ve really started looking at the risks,” explains Khera. “And in those 13 trials, the risk of major bleeding increased by about 43 percent in people taking aspirin compared to a placebo.”

“When I say major bleeding, I’m not talking about nosebleeds. We’re talking about bleeding in the brain, bleeding ulcers in the gut. Serious bleeding.”

The bottom line: “For most people, aspirin is causing more major bleeding than the heart attacks and strokes it’s preventing,” says Khera.

To his point, in the 13 trials, aspirin prevented one stroke or heart attack for every 241 people—and caused a major bleed for every 210 people—who took it for roughly five years.

What does that mean for you?

“If you’re at a higher risk for bleeding, you shouldn’t be on aspirin to prevent a first heart attack or stroke,” says Khera.

That includes everyone over age 70.

It also includes people of any age who have a history of ulcers or gastrointestinal bleeding, or are taking blood thinners, steroids like prednisone, or non-steroidal anti-inflammatory drugs or other medications that increase the risk of bleeding.

On the other hand, aspirin may be a good option for those whose risk for a first heart attack or stroke is high and whose risk of bleeding isn’t.

“Let’s say you have a very strong family history, and with imaging tests of the heart we can see that you have a lot of plaque buildup in your arteries,” says Khera. “Your doctor may recommend that you take aspirin.”

“We just have to be a bit smarter and more judicious about who we recommend it for. It’s a decision that should be made between a patient and their doctor.”

There’s one caveat

“We’re talking about people who have never had a heart attack or stroke,” says Khera. “If you’ve had either, these new recommendations don’t apply to you. Aspirin lowers the risk of a second event.”