Researchers took blood samples from 33 patients hospitalized for chest pain at Johns Hopkins Bayview Medical Center. Eighteen patients had acute coronary syndrome, or heart-disease-related chest pain, and 15 had non-cardiac chest pain. All took aspirin at 81 to 325 milligrams per day.
The Hopkins team treated the samples with very low doses of ADP and epinephrine medications that allow platelets, tiny disk-shaped structures within the blood, to clump together. They found that despite treatment with aspirin, platelets clotted together 5 percent to 10 percent more among the patients with heart disease than those without.
The work is to be presented Nov. 10 at the American Heart Association's 76th Scientific Sessions in Orlando, Fla.
"Even though these patients were receiving aspirin therapy, they still had very active platelets," says Marlene S. Williams, M.D., lead author of the study and assistant professor of medicine. The more the platelets clump together, the higher the chance of a clot forming, leading to a heart attack, she says.
Patients already taking daily aspirin should continue, Williams says. Her further studies will investigate the addition of other anti-clotting agents to aspirin therapy, and the study of abnormal genes that might affect platelet function.