People are much more likely to have another heart attack or stroke when they've already had one. Thanks to research in mice, we now know why.

The findings of the study, published in the Journal of the American College of Cardiology, could help prevent heart attacks and strokes from reoccurring.

After a heart attack, inflammatory cells and platelets were more likely to stick to the inner linings of arteries throughout the bodies of mice, especially in places where plaque was already present.

As a result, plaque becomes unstable, contributing to blood clots and future heart attacks and strokes, the research found.

However, when the rodents were treated with the antioxidant apocynin after a heart attack or stroke, their plaque buildup was cut in half and their inflammation was much lower.

"Our work helps understand why a heart attack in one region of the heart triggers a sudden major increase in risk for heart attack in other areas or for stroke,"  paper’s corresponding author, Jonathan R. Lindner, M.D., a professor of medicine (cardiovascular medicine) in the OHSU School of Medicine, OHSU Knight Cardiovascular Institute, said to ALN.

"The mechanism we found for enhanced risk, increased adhesion of platelets to the activated endothelium, is novel and most importantly potentially treatable.  It may also help understand mechanism of action of certain drugs that have been shown to reduce recurrent heart attacks (e.g. canakinumab)."