Video: Aspirin resistance

By Robert Bazell Chief science and health correspondent
NBC News
updated 7/21/2004 7:31:42 PM ET 2004-07-21T23:31:42

Twenty million Americans take a daily dose of aspirin to reduce their risk of heart disease and stroke. But now doctors are finding that aspirin, like most drugs, does not work the same in everybody.

Paul O'Connor has what is called “aspirin resistance.” He had his first heart attack a year and a half ago. His doctor put him on medications, including a daily aspirin, but he had two more heart attacks.

It turns out that, for O'Connor, aspirin does not have the blood-thinning effect that it has in most people. And it is that effect that reduces a person's heart-attack risk.

"We know that anywhere from 10 to maybe 30 percent of patients we treat with aspirin are not responding the way we hoped they would," says Dr. Lawrence Sperling, a cardiologist at Emory University Heart Center.

New tests released
Companies are now selling doctors blood-test kits and desktop machines to measure aspirin resistance. But the subject is so new that doctors are not sure what to do when they find out that someone is aspirin resistant. Many experts say they need experimental trials to get the answers.

"If you check every patient for their aspirin response, will it then lead to improving their outcomes?" asks Dr. Eric Topol, chairman of the Department of Cardiovascular Medicine at the Cleveland Clinic Heart Center. "Will it then enhance our ability to reduce the toll of death, heart attack or stroke?"

The answer may be higher doses of aspirin or different drugs. Despite these questions, doctors emphasize that for most people, aspirin reduces the risk of heart disease by 30 percent and costs only pennies a day.

"I think if their physicians counsel them to take a daily aspirin they should continue to take that aspirin," says Sperling.

But, researchers say, more studies are urgently needed to learn how best to treat people like Paul O'Connor, who do not seem to benefit.

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