'Aspirin Resistance' May Be Common

May 5, 2008 -- Some people who take aspirin to lower the risk of heart attacks and other clotting problems may have "aspirin resistance," according to a new research review.

In aspirin resistance, aspirin doesn't fully inhibit platelets in blood from sticking together. That anti-stickiness trait is the key to aspirin's clotting prevention.

The review, published in the Journal of the American College of Cardiology, supports aspirin therapy when doctors recommend it for heart health.

"Aspirin is likely to remain the cornerstone of antiplatelet therapy for long-term cardiovascular prevention," write the reviewers, who included Armen Yuri Gasparyan, MD, PhD, of City Hospital in Birmingham, England.

The reviewers read previous studies on aspirin resistance and wound up with more questions than answers.

For starters, the reviewers note a wide range of estimates on how common aspirin resistance is -- with estimates ranging from 5.5% to 60% of heart patients studied -- largely because there's no standard for defining and measuring aspirin resistance in lab tests.

It's also not clear what impact aspirin resistance has on patients' health, whether aspirin resistance develops over time, if it lasts, and if adding other antiplatelet drugs helps.

Smoking, obesity, diabetes, heart failure, inflammation, and other factors may boost aspirin resistance, the review shows.

The reviewers call for more studies to learn more about aspirin resistance and what to do about it.