Who Should Use Aspirin to Prevent Cardiovascular Disease?


Heart disease and stroke are the leading causes of death in the United States. For decades, a daily low-dose (baby) aspirin has been prescribed to lower the risk of a first heart attack or stroke in people with cardiovascular disease. But daily aspirin is not without risk of bleeding, and it’s not beneficial for everyone with heart disease.

The U.S. Preventive Services Task Force issued updated draft guidance for the use of low-dose aspirin to prevent heart attack, stroke, and other cardiac events in certain patient populations with heart disease based on age and risk. The committee, comprised of physicians that include proceduralists, general cardiologists, and epidemiologists, compiled a new data set using all existing studies on the topic. They examined best practices data, randomized trials, and meta-analyses to make new guidelines that are clear and easy to read but require a bit of context to understand.

While headlines ran with a black-and-white presentation of the Task Force draft guidelines, like “Taking aspirin to prevent heart attack may cause more harm than good,” cardiologists and cardiothoracic surgeons urge focus on the nuanced approach outlined by the guidance itself. After all, heart disease is as individual as we are.

To make sense of the chatter around these updated guidelines, we sat down with Isaac George, MD, heart surgeon and Surgical Director of the Heart Valve Center at Columbia.

Generally speaking, how did the recommendation of daily baby aspirin start, and who was it for?

Your risk of cardiovascular disease goes up as you age, and a daily dose of aspirin has been documented to reduce the risk of cardiovascular events in patients who have heart disease. It’s always been this way for those with heart disease and who haven’t had a cardiac event yet.

But there's always been the question, "Do you gain benefit if you are doing this for prevention purposes and if you have varying levels of cardiac disease? What’s the proper risk/benefit ratio in using aspirin for patients as they get older?”

Aspirin provides other benefits as you get older too. You'll reduce your risk of certain cancers, particularly colorectal cancer or colon cancer. And there are some anti-inflammatory benefits. But that is always offset by the downside of aspirin, which is gastrointestinal bleeding. And those events can have substantial morbidity and mortality, particularly in patients as they get older, they get re-admitted for hospitalizations. And those hospitalizations can be severe enough that it affects their overall lifespan. 

It seems that the general message had been “baby aspirin is good.” Does that mean a lot of people have been prescribed it indiscriminately and some have gotten complications from that? 

Yeah absolutely, that’s always been the message, and it was associated semantically with cardiovascular disease. So, the thought was, "Look, anyone who has any risk for cardiovascular disease should just be on a baby aspirin." And that was actually not uncommon, the message that was out there for a long time, 20, 30 years. 

And we weren’t focused on who really needs it and who doesn't need it. And I think that's what they're trying to do. The public message presented now is, "Maybe baby aspirin isn't helpful at all." And that's not necessarily the right message either. There is data from certain studies, including the Dallas Heart Study, that show that aspirin in patients who have a high calcium score, and patients who have higher risk scores, will be significant in reducing cardiovascular events.

So, there is data to support the use of aspirin in these patient populations. There's no question it can save lives.

How exactly have these new guidelines changed prescription practices?

These guidelines are an adjustment. They're trying to re-summarize the data in terms of its overall risk/benefit ratio in patients from varying cardiovascular risk levels as they get older and older, and as we've accumulated more and more data. You know, it says “people 40 to 59 should decide with their clinician whether to start taking aspirin, and people 60 or older should not start taking aspirin ” because the risk of bleeding could outweigh the benefit. From there we should do individual risk assessments.

So, these guidelines are really honing in on what’s best for the individual within age and risk parameters.

Exactly. A lot of the public message going around in response is, "Don't take aspirin, it's going to cause bleeding, it's not worth it, it's not going to help you." And that's not correct. I think it really just needs to be nuanced like you’re saying.

You’ve mentioned patients with high calcium scores and risk assessment scores, so, who are the patients who should take aspirin?

The data initially was always very positive, and everyone was on an aspirin. Now we've cut that down to a baby aspirin—patients are on 81 milligrams. We know that patients don't tolerate a full dose of Aspirin, and 81 milligrams will give the purported benefits for cardiovascular risk reduction without some of the other side effects.

So, right now, these guidelines are proposed to try to hone in on the populations that will really receive the best risk reductions on the cardiovascular side, and avoid the bleeding events in the patients that aren't going to generate as much benefit, or have no benefit, or have little data for its use.

What it's suggesting is that you continue to use aspirin for primary prevention of heart attack or stroke. Again, not for people who've had a bypass, or have had stents. It’s for patients who have not had a primary cardiovascular event. And to use aspirin if they have an accumulated risk of an event, by risk scores of greater than ten percent over ten years.

When talking about risk scores, how do you determine those metrics?

There are online calculators that you can use to determine risk scores. A number of different studies have supported the practice of using these risk scores. It's not something that we all practice on a daily basis, but it's something that we need to do more of when evaluating these kinds of risks.

I also think it's important to continue to use the literature that we have on risk stratification. One of the biggest things that we've been using in the last five years has been calcium scoring. So, patients who have some kind of risk level, and on their face, they look fine. Maybe they exercise, maybe they do the things that they need to do, or they tell you they are. But then you put them under a scanner and you get a calcium score, that's a really good way to figure out, "Are you high risk, low risk? Are you in-between?"

What does a calcium score tell you exactly?

A calcium score shows what your body has been producing in your coronaries and in your heart, and that gives you an estimation of what your event rate potentially would be. If you have a very, very high calcium score but you're very, very healthy and asymptomatic otherwise, what's your management strategy? We don't know exactly. But it does help us guide decisions, and it allows us to say, "Look, we need to watch you much more closely than the person that has a zero calcium score."

Someone, say, who has a very high calcium score but is otherwise healthy, would you recommend they take baby aspirin?

Yes, absolutely. And that is included in the draft guideline. Calcium scoring will work its way into that risk profile. If your calcium score is high, that will ultimately be reflected in that ten-year risk. 

Similarly, patients who are diabetic, patients who smoke, patients who have a strong family history of coronary disease, patients who have very abnormal lipids, or high blood pressure. These are all people that potentially may benefit from aspirin because their cardiac risk factors and their profile put them at higher risk.

So these guidelines will give the aspirin recommendation more definition, sort of catching up to the data on who benefits?

Yeah, I think so. And it really needs to be messaged properly so that the news media isn’t saying that no one should take an aspirin, because then we’re going to go the other way and potentially hurt a lot of people who would benefit greatly from it.

I think that definition, to use your word, will also help those 85-year-olds who maybe are not going to benefit from taking aspirin because they're at such high risk for a bleeding event.

Do the guidelines include recommendations for someone who has been taking baby aspirin for a while but is now 85 and maybe would no longer benefit due to risk and age?

I don’t know, that’s a good question. This is a preliminary release so we’ll know more when it comes out in full and is appropriately distributed. Hopefully, it will also reflect more robust suggestions of protocol management and strategies, because with this goes the added burden of what to do with patients who don't fit into any particular category. 

And so, I think we can expect that the guidelines will continue to provide very useful information. The draft is very, very interesting. It's actually very enlightening, and you can learn a lot from it. Hopefully, people don't just look at the headlines and take the time to read the draft or read the guidelines themselves. It’s not very long!

Looking at the headlines, there is a lot of “we used to think aspirin was good and now we know it’s bad.” And that sounds very misleading without the context.

Well, at the end of the day, risk matters. Risk stratification matters. I think it's good for patients to be aware of risk. It's good for patients to be aware of their own health, and health awareness is a lifesaver. And these kinds of decisions, aspirin or not, are not necessarily decisions that patients have to make alone.

I think they're best left to their physicians who have experience with this and can look at all of these things with a closer eye and with an understanding of some of the finer details. We want people to go see their physicians and ask them. It's always a discussion.

All of these numbers are just numbers and guidelines. They don't apply to individuals because individuals are not a lump sum. And all of these are personalized decisions that individuals, patients, doctors, have to make. Having the conversation is so important. We really have to be careful that we don't just read the headline, which is what everyone does, including me.

Absolutely.

You know, the use of pharmacology, in general, has changed. I think we're a little bit more specific on how much benefit we really get from all of these drugs. Now, we have an explosion of different kinds of drugs that are helping the heart.

We also have an explosion in the understanding of what imaging is showing us. How we use CAT scanning and physiologic scanning, things that we do in the cath lab, things that we do with CT or MRI. And then using that to figure out: “What is your risk of this kind of event?” And we can really put people into much finer buckets as opposed to 20, 30 years ago, where we say, "You're high risk or low risk." It’s exciting. And these aspirin recommendations are really useful in that regard, as care gets more and more individualized.

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