SATURDAY, March 24 (HealthDay News) -- Heart attack patients who take either a high or low dose of aspirin daily have the same level of protection against another heart attack or other cardiovascular events such as stroke, according to a new study.

Along with anti-clotting drugs, a daily aspirin is recommended for nearly all of the more than one million Americans who suffer a heart attack each year, but the most effective dose hasn't been determined.

Higher doses of aspirin typically come with higher bleeding risks, so determining whether a high dose is needed or not has patient safety implications.

To clarify the issue, researchers analyzed data from more than 11,000 heart attack patients around the world who were prescribed either a low daily dose (150 milligrams or less) or a high daily dose (more than 150 milligrams) of aspirin along with anti-clotting medications.

The findings were to be presented Saturday at the annual meeting of the American College of Cardiology in Chicago.

"We observed no difference between patients taking a high dose versus a low dose of aspirin as it relates to cardiovascular death, heart attack, stroke or stent thrombosis [clot]," lead author Dr. Payal Kohli, a cardiology fellow at Brigham and Women's Hospital, said in a hospital news release.

"Interestingly, we did find a dramatic difference in practice patterns of physicians in North America compared to those in the rest of the world," Kohli added. "North American physicians prescribed a high dose of aspirin for two-thirds of all their patients, while the exact reverse was true of the rest of the world. International physicians prescribed a low dose of aspirin to more than two-thirds of their patients."

Patients who received high doses of aspirin were more likely to have cardiac risk factors and higher cholesterol levels, while those who received low doses were more likely to be white and have no prior history of high blood pressure.

One expert said the study confirms there is "no role for high-dose aspirin" in this type of scenario. Dr. Jenifer Yu, a cardiologist and research fellow at Mount Sinai Medical Center in New York City, said she and her colleagues published similar findings at the American Heart Association annual meeting in 2011.

In that study, "after adjusting for baseline differences in the two groups, we found that the use of high-dose aspirin (greater than 200 milligrams) afforded no additional protection with respect to ischemic events [such as heart attack or stroke] in comparison to low-dose aspirin (less than 200 milligrams)," Yu noted. "However, patients on high-dose aspirin experienced more major bleeding," she added.

The newer study from Brigham & Women's also found that the anti-clotting drug prasugrel (brand name Effient) was more effective at preventing major cardiovascular events than the anti-clotting drug clopidogrel (brand name Plavix), regardless of whether patients took low- or high-dose aspirin.

Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal.

More information

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