Aspirin's Efficacy in MI Tied to Genetics

COLUMBUS, Ohio - Researchers who were looking for the reason why simple aspirin use protects some people from developing myocardial infractions (MI) have traced the mechanism back to a specific genetic factor present on the surface of clotting cells.

The discovery, published in The Lancet, could be used to determine which people at risk for MI and heart disease might benefit most from daily doses of aspirin and which people might need other non-aspirin drugs to gain the same effect.

Earlier studies have shown that about 25% to 50% of a normal population can reduce their risk of an MI if they take daily doses of aspirin. But until now, researchers didn't know why this beneficial effect was limited to such a small group of patients.

The new research suggests that aspirin may specifically target patients who display an altered gene, called P1^A2 polymorphism, which impacts upon the protective action of aspirin.

Glen Cooke, a post-doctoral researcher in the laboratory of Pascal Goldschmidt, chief of the division of cardiology and director if the Heart and Lung Institute at Ohio State, linked the existence of the P1^A2 polymorphism to aspirin's beneficial effects on the heart.

"We know that aspirin is a very efficient drug in the prevention of heart attacks," said Goldschmidt. "It reduces the risk of heart attacks by 25% to 50%, which happens to be, perhaps coincidentally, almost exactly the frequency of this polymorphism in Western society.

Genotyping in the future

Goldschmidt said that the effect of the polymorphism on MI is linked to the clotting of blood in the vessels of the heart. He said his researchers "showed that platelets in people who had the P1^A2 polymorphism were 10 times more sensitive to the effect of aspirin than were the platelets of individuals who do not have the polymorphism." Therefore, aspirin might be particularly indicated for patients with the P1^A2polymorphism.

Doctors may start genotyping their patients within a couple of years to determine if they have polymorphisms, Goldschmidt said. This information could help with the decision making process related to the choice of therapies.

For example, if a patient doesn't have the P1^A2 polymorphism but still has a problem with MI, patients might be given one of several other antithrombotic medications. ^CT

For more information:

Cooke GE, Bray PF, Hamlington JD, et al. P1^A2 polymorphism and efficacy of aspirin. Lancet. 1998; 351:1253