Staying on Low-Dose Aspirin Before Heart Surgery Deemed Safe

Study finds no increased risk of bleeding in 30 days after operation

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WEDNESDAY, Feb. 24, 2016 (HealthDay News) -- People taking a daily low-dose aspirin to protect their hearts can safely stay on the drug before they have surgery to treat clogged heart arteries, a large, new clinical study confirms.

The 10-year international trial showed that older adults who kept taking aspirin ahead of heart bypass surgery showed no increase in their risk of serious bleeding.

Experts said the findings, published Feb. 25 in the New England Journal of Medicine, help settle a longstanding question in heart disease care.

Most people with clogged heart arteries take a daily low-dose aspirin (typically 81 milligrams) to lower their risk of heart attack and stroke.

Right now, guidelines from the American College of Cardiology and American Heart Association (ACC/AHA) advise those patients to stick with aspirin when they're having heart bypass surgery.

That's based on the belief that the benefits of aspirin -- namely, preventing dangerous blood clots -- outweigh the risks of internal bleeding.

However, there's been some uncertainty about that guideline, because of a lack of evidence from large clinical trials, explained Dr. Paul Myles, the lead researcher on the new study.

He said his team's findings should bolster the ACC/AHA recommendation.

"We've shown that aspirin is safe for surgery," said Myles, director of anesthesia and perioperative medicine at Alfred Hospital and Monash University, in Melbourne, Australia.

"And given the known protective benefits of aspirin in daily life," Myles said, "we recommend that patients should stay on their aspirin if they're waiting to undergo open-heart surgery."

A U.S. cardiologist agreed. "This should be very helpful in encouraging people to stay on aspirin," said Dr. Robert Bonow, a former member of the ACC/AHA task force for performance measures.

Because it's common knowledge that aspirin carries bleeding risks, patients often ask whether they should stop the drug before surgery, according to Bonow, who is also a professor of medicine-cardiology at Northwestern University, in Chicago.

In some cases, Bonow said, patients might be told to temporarily stop aspirin ahead of a major surgery like hip or knee replacement.

But the situation is different with heart bypass surgery, which treats heart disease caused when multiple arteries are clogged with fatty plaques. A surgeon takes blood vessels from elsewhere in the body and uses them to re-route blood around the diseased arteries.

"The reason we suggest patients continue on aspirin is that it's important to keeping those bypass grafts from closing up," Bonow said, referring to the transplanted blood vessels. "Blood clots can form in the grafts, and some of those clots form soon after surgery."

Yet whether those benefits truly outweighed the bleeding risk had not been completely clear.

So, for the new study, Myles and his colleagues recruited 2,100 patients who were having heart bypass surgery, sometimes along with a heart valve replacement or other cardiac procedure. All of them faced a high risk of complications -- both bleeding and problems related to blood clots, including heart attack and stroke.

The patients were considered high-risk because of older age or other medical conditions, such as diabetes and high blood pressure.

About half were randomly assigned to start or stick with aspirin ahead of surgery; the rest were given placebo pills (but started on aspirin soon after surgery).

It turned out that aspirin patients were no more likely to suffer severe bleeding from their surgery. Around 2 percent of patients in both groups had a major hemorrhage, the study found.

But aspirin didn't seem particularly protective, either -- at least in the first 30 days after surgery. About 14 percent of aspirin patients had a heart attack, compared with just under 16 percent of placebo patients, the study showed.

That was surprising, Myles said. "But, many of our beliefs are subsequently shown to be wrong when tested in a proper clinical trial," he added.

Bonow cautioned, though, that the study looked only at short-term complications -- and it's known that aspirin has longer-range heart benefits. "I wouldn't want patients to think there is no point in taking aspirin," he said.

Both he and Myles saw the results as an endorsement of sticking with aspirin before heart bypass surgery, since the drug did not boost patients' bleeding risk -- even though they were often elderly or otherwise vulnerable to bleeding.

"That's encouraging," Bonow said, "since these are our highest-risk patients."

More information

The American Heart Association has more on aspirin and heart disease.

SOURCES: Paul Myles, M.D., M.P.H., director, anesthesia and perioperative medicine, Alfred Hospital and Monash University, Melbourne, Australia; Robert Bonow, M.D., professor, medicine-cardiology, Northwestern University Feinberg School of Medicine, Chicago; Feb. 25, 2016, New England Journal of Medicine
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