Only people with coronary artery calcium (CAC) scores of 100 or greater should undergo aspirin therapy to prevent a heart attack, concludes a study published in Circulation: Cardiovascular Quality and Outcomes.
The retrospective analysis of data from 4,229 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) aimed to distinguish who would and would not benefit from aspirin therapy, which carries a risk of bleeding, according to the researchers from several U.S. institutions (Circ Cardiovasc Qual Outcomes, May 6, 2014).
Limiting aspirin treatment to those at high risk of cardiovascular disease will miss a number of patients who will eventually have a heart attack, noted lead author Dr. Michael Miedema from the Minneapolis Heart Institute in a statement. However, liberally prescribing aspirin increases the risk of bleeding for many who would never experience a heart attack. The goal of the study was to go beyond traditional risk factors to determine who should and should not take aspirin.
The participants had no known history of cardiovascular disease or diabetes and were not on aspirin therapy; they were grouped according to calcium score and followed for approximately seven years. Based on the rates of heart attack, the study team weighed the likelihood of an individual benefiting from aspirin therapy against the likelihood of aspirin causing major bleeding.
The researchers estimated that participants with CAC scores of at least 100 were two to four times more likely to benefit from aspirin therapy than to be harmed by it, even if they didn't qualify for aspirin use based on American Heart Association guidelines. On the other hand, MESA participants with no calcified plaque (CAC score of 0) were two to four times more likely to be harmed by aspirin use than to benefit from it. Accounting for traditional risk factors did not change the results.
Individuals with significant plaque are far more likely to prevent a heart attack with aspirin use than to suffer a significant bleed, according to Miedema. On the other hand, having no calcified plaque means the risk of heart attack is very low, so aspirin use would more likely hurt than help, even for individuals with high cholesterol or a family history of disease.
