Aspirin's blood-thinning capabilities have long made it a routine medication for certain people with a high risk of heart attack or stroke.

But is this changing?

The U.S. Preventive Services Task Force (USPSTF) recently finalized new recommendations for using low-dose aspirin as a means of broadly preventing heart disease and its life-threatening complications, advising against initiating daily aspirin in adults 60 years or older, in particular.

While these formal guidelines may be changing, Dr. Joshua Septimus, associate professor of clinical medicine, says the shift isn't surprising — or new — to him and other doctors.

"We stopped prescribing low-dose aspirin as a way to prevent heart attack and stroke in people who haven't yet developed significant heart and vascular disease years ago," says Dr. Septimus. "The guidelines will now simply reflect what we've already been practicing in the clinic for quite some time."

This isn't to say aspirin can't play a role in reducing the risk of experiencing a cardiovascular event for some — it can, especially if a person's risk is high. However, taking aspirin every day, even a low dose, comes with risks itself.

"Daily low-dose aspirin has its place in the heart disease prevention and treatment landscape, but it's certainly not always needed," Dr. Septimus adds.

What is low-dose aspirin and why is it taken for heart disease?

"If a person's blood vessels are narrowed due to plaque buildup, the arteries are in a diseased state called atherosclerosis," explains Dr. Septimus. "The more plaque, the more likely plaque rupture becomes. When this happens, it triggers a cascade of clotting and inflammation that can lead to heart attack and stroke."

As a blood thinner, aspirin can help reduce the risk of plaque rupture, as well as some of the resulting clotting — thereby reducing the risk of heart attack and stroke in someone who has substantial buildup.

"The dosage needed to accomplish this is lower than what's typically needed for pain relief, which is why doctors prescribe low-dose aspirin, also called baby aspirin," says Dr. Septimus.

These lower doses typically range from 75 to 100 milligrams. The most common low dosage used is 81 milligrams.

"The issue with aspirin, even at these low doses, is that it can cause gastrointestinal bleeding, ulcers and, in severe cases, hemorrhagic stroke," Dr. Septimus warns. "This means the benefits of taking aspirin every day must be carefully weighed against its risks. That's why we don't prescribe it unless a person actually has atherosclerosis."

What caused the low-dose aspirin guidelines to shift?

After last meeting on the topic in 2016, the USPSTF recently reconvened to discuss the role that low-dose aspirin should — and shouldn't — play in the prevention of heart disease and its complications. New recommendations that were drafted and released in October 2021 are now finalized as of April 26, 2022.

The new recommendations set by the task force are that:

• Taking daily low-dose aspirin for primary prevention of heart disease in adults 60+ shows no clear benefit.
• Taking daily low-dose aspirin for primary prevention of heart disease in adults 40-59 who have a 10-year atherosclerotic cardiovascular disease (ASCVD) risk of 10% or higher may have a small benefit.
  
  

"Primary prevention means you're at risk for heart disease and preventive steps are needed to reduce this risk, but there's no evidence that your arteries are actually diseased and you haven't yet had a heart attack or stroke," says Dr. Septimus.

Rather than taking low-dose aspirin every day, your doctor may recommend reducing your heart disease risk by making lifestyle changes, such as:

• Adopting a heart healthy diet
• Getting plenty of exercise
• Monitoring your cholesterol and taking steps to control it if it's high
• Monitoring your blood pressure and managing if it's high
• Managing diabetes if you have it
• Stopping smoking if you smoke
  
  

"Our understanding of health and how best to prevent and treat disease is always evolving, and this shift in guidelines is just one example of that," says Dr. Septimus. "New information changed the way we approach heart attack and stroke prevention. These changes were already implemented in clinics, so the guidelines are being formally updated to reflect that."

Who should take low-dose aspirin — and who shouldn't?

Your doctor may prescribe low-dose aspirin to prevent heart attack or stroke if you've already had one or if you have known heart disease. This is considered secondary prevention of heart disease.

In addition, according to the USPSTF, low-dose aspirin for primary prevention of heart disease is still acceptable for adults aged 40-59 with a certain level of risk of heart attack — at least 10% risk or higher, as estimated by the ACC/AHA's 10-year ASCVD risk calculator.

However, it's critical to work with your doctor to understand what this estimate actually means for you, even if you've had a heart attack previously or have conditions that increase your risk of having one, like diabetes and obesity.

"The reality is that this risk assessment can't confirm you actually have plaque in your arteries, which is the only time the benefits of aspirin outweigh the risks," warns Dr. Septimus. "This model simply estimates your risk of atherosclerosis using your demographic information, blood work and health conditions — so it's not the only factor to consider."

One powerful piece of information your doctor can use to determine your actual level of risk is your coronary artery calcium (CAC) score. The score provides a measurement of the amount of plaque you have in your arteries.

"The higher your CAC score, the more plaque you have in your arteries," says Dr. Septimus. "It's a much more accurate representation of your true risk of heart attack and stroke and can help confirm whether you might benefit from daily low-dose aspirin or not."

Plus, even if your estimate puts you at high risk and even if you do have plaque in your arteries, your doctor will need to run tests to make sure you're not at increased risk for bleeding, since this could exacerbate the inherent bleeding risk associated with taking aspirin.

"Most importantly, while low-dose aspirin is available over the counter, it shouldn't ever be taken daily without a doctor's recommendation," says Dr. Septimus.

And if you're already taking aspirin but are concerned about the new guidelines, be sure to consult your doctor for guidance.

"These new guidelines are a reflection of what doctors have already been practicing in the clinic for years," Dr. Septimus reminds us. "If your doctor has prescribed low-dose aspirin, do not stop taking it before speaking with him or her."