Many people with heart issues take an aspirin every day, but a team of researchers has found that the little white pill is of no benefit, and could even be dangerous, for one group of heart patients who took aspirin for three years.

The research, presented Saturday to heart-rhythm specialists meeting in Chicago, involved more than 4,000 people who suffer from an irregular heart rate a condition known as atrial fibrillation and who have been treated with a catheter ablation, a procedure that destroys damaged tissue in the heart.

In these patients, long-term use of aspirin can put them at risk for gastric and genitourinary bleeding and did not reduce their risk for strokes, Dr. Jared Bunch, director of Heart Rhythm Research at Intermountain Medical Center Heart Institute, said.

The findings are important, Bunch said, because of the widespread acceptance of aspirin as a therapy for people with heart problems. While aspirin can be helpful, even life-saving, for people who have heart disease, it's not a catch-all therapy for every type of heart issue, which is why people should use aspirin with caution and only when advised by a physician.

Unfortunately for physicians as well as consumers, aspirin is readily available. A person can come in and say they don't want anything prescribed, or they don't even want to come in, and they can go to any grocery store and pharmacy and get any number of aspirins, and most are labeled heart-healthy and have some self-promotion in that regard, Bunch said in an interview prior to his presentation before an international gathering of The Heart Rhythm Society.

Bunch and his team were not surprised to find that aspirin did not appear to prevent strokes in the patients; little evidence has been presented to support that idea, he said.

But, the magnitude of bleeding we were seeing did surprise us, Bunch said, adding this warning:

People shouldnt use aspirin daily for heart health unless its prescribed by a physician. And for atrial-fibrillation patients at low-risk for stroke the risk further lowered by ablation long-term aspirin use really conveys risk without benefit.

The word "aspirin" was invented by Bayer in 1899, but it eventually became a generic term for acetylsalicylic acid. For thousands of years before aspirin became a pill, its natural components, derived from bark of the willow tree, were crushed into a powder and given to women to help alleviate the pain of childbirth, according to the website Aspirinproject.org, which promotes aspirin's use.

Just a half-century ago, aspirin was the go-to painkiller in the family medicine cabinet, but it was pushed aside by acetaminophen and ibuprofen.

Fortuitously for aspirin makers, the drug's anticoagulant properties gave it a second life on pharmacy shelves, and America's rising rates of heart disease ensure that it continues to sell. Heart disease is the No. 1 cause of death in the U.S., according to the Centers for Disease Control and Prevention.

Dr. Matthew Roe, a cardiologist and professor at the Duke University School of Medicine in Durham, North Carolina, said that research in the 1970s and '80s found that aspirin could significantly reduce mortality among some heart patients, leading it to become a cornerstone therapy for many heart conditions over the past 30 years.

Bottles of Bayer aspirin are stamped with a heart and bear the words "I am pro-heart," and the company urges "Carry aspirin, save a life."

"In the event of a suspected heart attack, call 911 and chew or crush aspirin as directed by a doctor," a Bayer website says.

The "directed by a doctor" part is key.

When confronted with a medical emergency, the victim or panicked family members might not be able to distinguish between a heart attack which occurs when blood flow to the heart becomes blocked or a stroke, which is the interruption of blood flow to the brain.

Most strokes are caused by blood clots, but some involve ruptured blood vessels, and taking aspirin during a hemorrhagic stroke could worsen the person's condition, the American Heart Association says. If a doctor is not available, a 911 operator can help determine if an aspirin should be taken in an emergency.

The Heart Association does recommend that people at high risk of a heart attack, as well as heart-attack survivors, take a low-dose of aspirin daily if recommended by their physicians.

Its still unknown what dosage is most helpful, however, and Duke is conducting a clinical trial of 20,000 people to determine what dosage is best. A baby aspirin has 81 milligrams of aspirin; adult-strength is 325.

The Intermountain study did not distinguish between amounts of aspirin used, Bunch said.

Not for everyone

Jennifer Merback, spokeswoman for the American Heart Association in Utah, said the Heart Association warns that certain people should not take aspirin, including those who drink alcohol regularly, who are at risk for gastrointestinal bleeding or hemorrhagic stroke or are about to undergo medical or dental procedures.

"You should not start aspirin on your own," the group's website says.

Atrial fibrillation is the most common form of irregularity in heart rhythm, affecting up to 6 million people in the U.S., and nearly 1 in 10 of Americans 65 and older.

While atrial fibrillation can increase the risk of a stroke, a catheter ablation and follow-up treatment reduces it, which is why some physicians have treated these patients with aspirin to further lower their risk.

Researchers, however, found that any benefit of aspirin for the patients they studied ended after one year, Bunch said.

"After a year, if they remain in a normal rhythm and they're considered low-risk for stroke, we didn't see any further reduction in stroke risk. At the same time, we saw significantly increased risk of stomach as well as genitourinary bleeding, and we saw a slightly higher risk of stroke in those who continued on aspirin," Bunch said.

Aspirin did appear to benefit one subgroup of atrial-fibrillation patients in the Intermountain study: those who have already had a heart attack, bypass surgery or stent.

"For those people, there still appears to be a role for aspirin, not necessarily alone, but in combination with a stronger blood thinner," Bunch said.

"Since stroke is the most feared complication of AF, we need to continue to study all available therapies to understand the most effective and safest treatment choices and how to use them after ablation."