CAC scanning proves aspirin is not a one-size-fits-all way to prevent heart attack, stroke

A coronary artery calcium (CAC) scan can help doctors distinguish between patients who are safe to take preventative aspirin and those who should not due to bleeding risks, according to a new study published Wednesday. 

Aspirin’s anti-clotting elements have made it a widely prescribed primary safeguard against heart attack or stroke. But recently, the American Heart Association and American College of Cardiology both changed guidelines to recommend more judicious use for individuals at high risk of adverse cardiac events.

“We used to say for aspirin, generally yes, occasionally no,” Amit Khera, MD, director of UT Southwestern’s Preventative Cardiology Program, said in a statement. “With these new guidelines, we’ve flipped that on its head and are saying that we should not use aspirin for most people in primary prevention.”

For their study, the researchers used data from more than 2,100 participants who were part of an ongoing investigation tracking the development of cardiovascular disease in 6,000 Dallas County adults.

The volunteers, who were 57% female and 47% Black, completed three visits to collect health and demographic information, lab samples, and multiple imaging studies, including CAC scanning. They were followed for 12 years, on average, to track cardiac outcomes.

After looking at the patients’ rates of atherosclerotic cardiovascular disease (ASCVD) and bleeding, Khera et al. found both outcomes increased in a graded fashion as CAC scores rose.

And using a statistical model, the researchers noted that aspirin’s benefits only outweighed its risks for people with CAC scores above 100. For these participants—about 7% of the study group—ASCVD and bleeding risk was about 15-fold and threefold, respectively, of those with a CAC score of zero.

This phenomenon, the authors noted, only occurred in patients with an inherently low risk for bleeding. With that in mind, an individual should not take aspirin for primary prevention if they had prior bleeding episodes, bleeding risk factors, or prescribed medications that increase bleeding, Khera and colleagues wrote.

“Aspirin use is not a one-size-fits-all therapy,” Khera added. “CAC scanning can be a valuable tool to help us tailor care to help more patients avoid a first heart attack or stroke.”

Read the entire study published Oct. 28 in JAMA Cardiology here.