Aspirin and Heart Disease

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Updated:Jan 27,2015

Aspirin can help prevent heart attack. 

AHA Recommendation People at high risk of heart attack should take a daily low-dose of aspirin (if told to by their healthcare provider) and that heart attack survivors regularly take low-dose aspirin.

You should not start aspirin therapy without first consulting your physician.  The risks and benefits of aspirin therapy vary for each person.

Know the risks
Because aspirin thins the blood, it can cause several complications. Talk to your doctor if any of these situations apply to you. You should not take aspirin if you:

• Have an aspirin allergy or intolerance
• Are at risk for gastrointestinal bleeding or hemorrhagic stroke
• Drink alcohol regularly
• Are undergoing any simple medical or dental procedures

Preventing Heart AttackMost heart attacks and strokes occur when the blood supply to a part of your heart muscle or brain is blocked. This usually starts with atherosclerosis, a process in which deposits of fatty substances, cholesterol, cellular waste products, calcium and other substances build up in the inner lining of an artery. This buildup is called plaque.

Plaque usually affects large and medium-sized arteries. Plaques can grow large enough to significantly reduce the blood's flow through an artery. But most of the damage occurs when a plaque becomes fragile and ruptures. Plaques that rupture cause blood clots to form that can block blood flow or break off and travel to another part of the body. This is called an embolism.

• If a blood clot blocks a blood vessel that feeds the heart, it causes a heart attack.
• If a blood clot blocks a blood vessel that feeds the brain, it causes a stroke.

Aspirin “thins” the blood and helps prevent blood clots from forming. So it helps prevent heart attack and stroke.

Frequently Asked Questions About Aspirin

What about aspirin and alcohol?
There is a risk of stomach problems, including stomach bleeding, for people who take aspirin regularly.  Alcohol use can increase these stomach risks, so ask your doctor if it is safe for you to drink alcohol in moderation.

Should I take aspirin during a heart attack or stroke?
The more important thing to do if any heart attack warning signs occur is to call 9-1-1 immediately.  Don't do anything before calling 9-1-1.  In particular, don't take an aspirin, then wait for it to relieve your pain.  Don't postpone calling 9-1-1.  Aspirin won't treat your heart attack by itself.

After you call 9-1-1, the 9-1-1 operator may recommend that you take an aspirin.  He or she can make sure that you don't have an allergy to aspirin or a condition that makes using it too risky. If the 9-1-1 operator doesn't talk to you about taking an aspirin, the emergency medical technicians or the physician in the Emergency Department will give you an aspirin if it's right for you.  Research shows that getting an aspirin early in the treatment of a heart attack, along with other treatments EMTs and Emergency Department physicians provide, can significantly improve your chances of survival.

Taking aspirin isn't advised during a stroke, because not all strokes are caused by blood clots.  Most strokes are caused by clots, but some are caused by ruptured blood vessels.  Taking aspirin could potentially make these bleeding strokes more severe.
The best way to know if you’re a candidate for aspirin therapy is to ask your healthcare provider. You should not start aspirin on your own.

Daily aspirin fails to prevent heart attacks, increases bleeding risks

Editor’s note: This is the eighth in a 10-part series detailing the top scientific research of 2014, as determined by the American Heart Association’s volunteer and staff leaders.

Aspirin is known to help reduce heart attacks in people who have already had one, but a large-scale study in Japan points out the lack of benefits and the risks of daily aspirin for people without heart disease.

Aspirin thins the blood to help prevent blood clots. It’s often used to prevent recurrent heart attacks and strokes, and it’s given to those who have stents to clear blocked arteries. The American Heart Association recommends that healthcare providers prescribe daily low-dose aspirin to heart attack survivors and consider prescribing it to people who are at high risk of heart attack and low risk of side effects.

But daily aspirin didn’t reduce the risk of heart attack, stroke or death for elderly Japanese people who were at risk, according to a study published in the Journal of the American Medical Association and presented at the American Heart Association’s Scientific Sessions 2014.

Researchers in Kyoto, Japan randomly assigned 100 mg a day of coated aspirin or no aspirin to 14,464 people, ages 60 to 85 with high blood pressure, high cholesterol or diabetes, but without coronary or cerebral artery disease. After five years, the two groups had no significant differences in heart attacks or strokes. Events were 2.77 percent for the aspirin-treated group compared to 2.96 percent in the no-aspirin group.

The results of the trial are among the top scientific cardiovascular developments in 2014, as determined by the American Heart Association.

“The available evidence does not support the routine use of aspirin in the primary prevention of cardiovascular events,” said Richard Becker, M.D., an AHA volunteer and director and physician-in-chief at the Heart, Lung and Vascular Institute at the University of Cincinnati College of Medicine in Ohio.

Despite a drop in heart attacks in the aspirin group, bleeding risks increased, including fatal and nonfatal bleeding strokes.

“Physicians should know this. In contrast, aspirin should be considered in all patients with knownatherosclerotic disease, particularly with prior events such as a heart attack or stroke, stent or bypass surgery,” Becker said. “The public and also many physicians have viewed aspirin as both safe and effective for primary prevention, despite an absence of resounding proof of benefit. It is associated with a clear risk for bleeding, including serious gastrointestinal and less commonly intracranial hemorrhage.”

Deepak L. Bhatt, M.D., M.P.H., an AHA volunteer and executive director of Interventional Cardiovascular Programs at Brigham and Women’s Hospital Heart and Vascular Center in Boston, said the study results are consistent with previous studies.

“I think the decision to use aspirin for primary prevention in a patient needs to be individualized by the physician after a thoughtful discussion,” Bhatt said. “I would not routinely recommend aspirin for primary prevention unless future trials show a clear benefit.”

Heart disease and aspirin therapy

Heart disease and aspirin therapy

Aspirin is one of the oldest, best-selling and most familiar drugs around.

About one in five American adults regularly take aspirin, according to the U.S. Agency for Healthcare Research and Quality. Many are heart attack and stroke survivors who take an aspirin a day to lower the chance of having a repeat heart attack or clot-related stroke — a strategy called secondary prevention. For this group, the evidence is clear that daily low-dose aspirin can be beneficial.

But for another group of aspirin-takers, the evidence is less compelling.

They are people hoping to prevent a first heart attack or a first stroke, and who use aspirin as a method of primary prevention. But recent studies suggest the benefits do not always outweigh the risks of daily aspirin use, which can include bleeding and other side effects.

“Aspirin is an effective and important treatment to prevent a heart attack or stroke in someone who has a history of heart disease or stroke,” said Mark Creager, M.D., president-elect of the American Heart Association and director of the Vascular Center at Brigham and Women’s Hospital in Boston. “That’s not the case for the healthy person who’s at low risk for these events.”

Most heart attacks and strokes occur when blood flow to the heart or brain is blocked by a blood clot. Aspirin works by “thinning” the blood and preventing the formation of clots.

But aspirin can cause complications. When blood cannot clot easily, excessive bleeding can occur. A burst blood vessel in the brain can cause a hemorrhagic stroke. Some people have bleeding in the stomach or elsewhere in the gastrointestinal tract.

Most side effects of aspirin include upset stomach and heartburn. More serious side effects are uncommon — but they can be life-threatening.

“Many people who take aspirin will notice it’s harder to stop the bleeding when they get a cut. But these people are also at risk for potentially catastrophic bleeding,” Creager said.

How aspirin should be used

Aspirin has long been a medicine cabinet staple. It is used to relieve pain, reduce fevers and calm inflammation. Then in the 1970s, aspirin’s reputation got a boost: Studies started finding that aspirin could also help prevent heart attacks and strokes in people who had already had one.

Research shows that among heart attack survivors, regular aspirin use can reduce the risk of a second heart attack, stroke or cardiovascular-related death by about 25 percent. For stroke survivors, it lowers the risk of a second event by about 22 percent.

For heart attack survivors, the risk of having another heart attack or a stroke is 4 percent to 5 percent a year, said Creager. “If you cut that risk with aspirin by 25 percent over five years, that’s pretty substantial,” he said.

Today, more than two-thirds of heart disease and stroke survivors age 40 and older take low-dose aspirin to prevent a recurrence, according to data from the Centers for Disease Control and Prevention.

Others also benefit from clot-preventing aspirin, including patients who get stents placed into heart arteries. Doctors often prescribe daily aspirin to prevent the stents from becoming blocked.

A new study, presented last November at the AHA’s Scientific Sessions 2014 and published in the New England Journal of Medicine, found that long-term use of aspirin plus a second anti-clotting medication cut the risk of having a heart attack by more than half in people who had received a stent.

Daily aspirin not for everyone

Experts agree that aspirin can help thwart a second heart attack or stroke. Yet for those without such a history, research suggests the drug’s risks may offset the benefits.

That advisory came last May from the U.S. Food and Drug Administration, which warned that the over-the-counter drug should not be used for primary prevention of heart attacks and strokes.

The likelihood of having a heart attack or ischemic stroke is about half a percent a year among people without cardiovascular disease, noted Creager. “For them, aspirin has a very modest effect in reducing the risk of heart attack, and it may put them at increased risk for bleeding,” he said.

Indeed, a Japanese study recently found that among older people with high blood pressure, high cholesterol or diabetes — three major risk factors for heart attack and stroke — taking a low-dose aspirin every day did not reduce the overall risk of heart attack, stroke or death. Yet aspirin users had an 85 percent higher risk for bleeding inside the skull and were more likely to have gastrointestinal bleeding.

The findings were presented at the AHA’s Scientific Sessions 2014 and published in the Journal of the American Medical Association last November.

Because of the bleeding risk, AHA guidelines only recommend daily low-dose aspirin for primary prevention in people with a greater than 10 percent risk of having a heart attack or stroke within the next 10 years.

Creager helped write the AHA’s 2014 guidelines for the primary prevention of stroke and urges people to talk to their doctors about whether their individual risk is high enough to warrant aspirin therapy or a similar drug.

“If you’re healthy and at low risk, you should not be prescribed aspirin,” said Creager. “But if your doctor does prescribe it, you need to understand why.”