Atherosclerosis is a condition in which plaque builds up inside the arteries, leading to hardened, narrow, or even blocked arteries. The damage caused by atherosclerosis may contribute to a range of cardiovascular conditions, such as coronary heart disease or peripheral artery disease. New research rethinks the impact of plaque buildup on heart disease.
Atherosclerosis refers to the buildup of plaque in the arteries that are normally responsible for carrying blood to various vital organs of the body.
The plaque that builds up is made of cholesterol, fat, or calcium. Previous research has suggested that it is the soft - that is, noncalcified and lipid-laden - plaque that holds the highest risk of rupturing and triggering heart attacks.
However, new research - presented at the American College of Cardiology Scientific Sessions, in Washington, D.C. - indicates that the opposite may be true. The new study, conducted by researchers from the Intermountain Medical Center Heart Institute in Salt Lake City, UT, suggests that hard, calcified plaque may be a stronger indicator of adverse cardiovascular events.
Studying the link between heart conditions and different kinds of plaque
The scientists analyzed the composition of coronary artery plaque in 224 patients who had diabetes but who showed no signs of heart disease. The patients were registered with the Intermountain Medical Center Heart Institute, and the data were collected as part of a previous study carried out in collaboration with the Johns Hopkins School of Medicine and National Institutes of Health (NIH).
The new research focused on the long-term associations between plaque buildup and cardiovascular disease, as the scientists followed the patients for almost 7 years, on average.
To analyze the composition of the plaque, the researchers used a coronary angiography performed with computed tomography (CT).
The CT scan was stratified into layers of noncalcified, calcified, and fibrous plaque. The researchers correlated the data with the calculated risk of unstable angina (a condition in which the heart does not receive enough oxygen-rich blood), heart attack, and death.
Hard plaque predicts major coronary conditions
The study revealed that higher amounts of calcified plaque strongly predicted serious coronary conditions.
"It is a disease marker, not a risk marker. And we think it is possibly a very important predictor," says Dr. Brent Muhlestein, one of the study's authors and co-director of cardiology research at the Intermountain Medical Center Heart Institute.
Dr. Muhlestein also explains the importance of the findings for heart disease diagnosis and treatment:
"The finding potentially could mean a lot of patients may not require statin therapy, even though they have high cholesterol. Maybe we can find and identify them. If there is no atherosclerosis, you are not going to have a heart attack. So the coronary calcium score may allow us to much more effectively select who we treat."
Although the calcium deposits cannot be completely removed from the arteries, aggressive statin therapy can improve the health outcomes for patients with atherosclerosis. Additionally, the new findings may change the way that physicians determine who is at risk of heart attack or heart failure.
Dr. Muhlestein notes that more studies are needed to confirm their findings, as well as to understand the mechanism behind this correlation.
"We need further validation to gauge the importance of why the coronary calcium score is so predictive," he says.
The researchers will carry out more scans in the hope that the new data will reinforce their findings.