Should you be taking a daily aspirin to prevent a heart attack or stroke?

For decades, taking a low-dose aspirin to prevent heart attacks and strokes has been the standard advice. When the news hit recently that the U.S. Preventative Services Task Force has reversed that advice as an automatic recommendation for middle-aged people because of an increased risk of bleeding issues, patients were confused, and doctors were left to explain.

There’s no reason to panic or automatically stop taking a daily aspirin, said Cardiologist Lawrence McAuliffe, MD, at Cape Cod Healthcare Cardiovascular Center in Hyannis. The aspirin “news” isn’t really even news, he explained, and it only applies to those who have not already had a cardiovascular event.

“As long ago as 10 years ago, the advice was not to take aspirin simply as a primary preventative strategy,” he said. “Obviously, there is a big difference between primary and secondary prevention. Primary prevention is to prevent the initial event. Secondary is you have had an event and are trying not to have another one.” 

The old guidelines for prevention of secondary events remain the same. Anybody who has had any kind of cardiovascular event such as a heart attack, aborted heart attack, stent, or stroke should be on an aspirin or possibly a prescription blood thinner, depending on what their diagnosis was, he said.

But there are always exceptions to every rule and doctors need to look at the patient in front of them, rather than blindly following guidelines, Dr. McAuliffe said. He used the example of a 50-something-year-old man who has not had a heart attack, but is overweight, diabetic, hypertensive and smokes. A cardiologist would use a risk calculator to establish what that patient’s actuarial risk would be over the next 10 years.

“In addition to aggressively treating all of their cardiovascular risk factors, if they are judged to be high risk, which would be a better than 10 percent risk of a major cardiovascular event over the next ten years - defined as heart attack, stroke or death - then that person may well be someone who ought to take an aspirin as part of their treatment regimen and strategy,” he said.

But if that same patient had five diverticular bleeds or had a hemorrhagic event at some point, or had bleeding in their urine, in the absence of a documented cardiac event, a doctor may choose not to treat that patient with aspirin because the risk of dangerous bleeding might be worse than the risk of a cardiac event.

Patients with atrial fibrillation also need a more customized approach to treatment. Since atrial fibrillation is associated with about a fivefold increased risk of ischemic (blood clot) stroke, doctors try to maximize their protection against vascular ischemic events, which include taking aspirin and Plavix. They may also try to protect against the thrombotic events from atrial fibrillation by prescribing Coumadin or one of the newer blood thinners.

For that patient, taking three blood-thinning agents at the same time really ups the ante for bleeding events, so a doctor might prescribe all three for a month and then drop the aspirin from the regimen.

“We are always thinking about what conditions are we treating and what is the least amount of medication we can use, thereby exposing the patient to the least amount of risk by overmedication, but at the same time not under-medicating so we don’t adequately protect them.

It’s always about the individual patient and information at hand and the physician’s best guidance for that particular patient,” Dr. McAuliffe said.

Part of the reason the guidelines changed goes back to how the aspirin advice began in the first place. In the 1980s, researchers did a study of 22,071 physicians to evaluate the role of aspirin in the prevention of cardiovascular mortality. The Physicians’ Health Study was terminated three years early because the results were so impressive. After five years of follow-up, there was a 44% reduction in the risk of a first myocardial event.

Around the same time, the Nurses’ Health Study of 79,319 women showed a small dose of daily aspirin reduced cardiac events and strokes. Both studies were skewed by their included populations, Dr. McAuliffe pointed out. Doctors aren’t representative of the general population and the nurses’ study was all women. But nevertheless, the recommendation took hold.

“The preventative advice was to give aspirin to men and women to reduce stroke and heart attack,” he said. “So that became the guidance that people were receiving in that time-frame. They acknowledged that people on aspirin antiplatelet treatment can have bleeding issues but the feeling was that we were preventing enough cardiovascular events to justify what was thought to be a relatively minor risk of those bleeding events.”

Over time, the guidelines from the American Heart Association, the American College of Cardiology and the European Heart Association began to recognize that not everyone should be on aspirin, so the guidelines changed.

“We apply the best guideline-directed medical therapy that we have now, and that changes over time,” Dr. McAuliffe said. “Here’s a recommendation that was fairly robust back in the 80s and 90s, which, while still having some importance today, is no longer the broad-brush recommendation now that it was then.”