NEW ORLEANS — Apparently healthy people with a family history of coronary artery disease who also had metabolic syndrome showed elevated platelet aggregation and reduced platelet responsiveness to aspirin in a study of more than 2,000 people.
These findings suggest that “low-dose aspirin therapy alone may not be sufficient to provide optimal antiplatelet protection” in people with metabolic syndrome and an increased risk for coronary artery disease, Dhananjay Vaidya, Ph.D., and his associates reported in a poster at the annual scientific sessions of the American Heart Association. The link between metabolic syndrome and aspirin resistance in platelets was examined because metabolic syndrome is known to be proinflammatory and prothrombotic, they said.
The study involved 2,088 apparently healthy siblings, sibling offspring, and coparents of the sibling offspring of more than 500 patients who were younger than 60 years and hospitalized for coronary artery disease. The average age of the relatives was about 44 years, and about 58% were women. The group included 591 people (28%) who met the criteria for metabolic syndrome of the Adult Treatment Panel III guidelines of the U.S. National Cholesterol Education Program; the remaining 1,497 people (72%) did not have metabolic syndrome.
After a baseline assessment and blood collection, the subjects were treated with 81 mg/day of aspirin for 2 weeks and then were reassessed and had a second blood specimen drawn. The aggregability of each person's platelets was tested before and after aspirin treatment with two different in vitro assays. In one assay, the platelets were treated with arachidonic acid; in the second, they were treated with urinary thromboxane B2.
Before starting aspirin, the platelets of the people with metabolic syndrome showed significantly more aggregation in both in vitro assays than the platelets from people without metabolic syndrome in an analysis that adjusted for baseline differences in age, gender, race, serum levels of LDL cholesterol and high sensitivity C-reactive protein, and smoking status, said Dr. Vaidya, a vascular researcher in the department of medicine at Johns Hopkins University, Baltimore, and his associates.
Immediately after 2 weeks of daily aspirin treatment, the platelets of the people with metabolic syndrome continued to show a significantly higher level of aggregation, compared with platelets from those without metabolic syndrome, in both assays, again in an analysis that adjusted for the same baseline differences.
The finding has clinical implications because aspirin prophylaxis for coronary artery disease is recommended for metabolic syndrome, said the researchers.