CT scans of calcified plaque in the arteries of the heart may do a better job of predicting whether a patient will have a heart attack than if he or she will have a stroke, new research has revealed.
The more calcified plaque accumulates in the arteries, the more visible it becomes on a CT scan. In a study published August 18 in Circulation: Cardiovascular Imaging, researchers from the University of Texas Southwestern Medical Center examined how well the coronary artery calcium (CAC) score from these scans can predict whether a patient will experience a heart attack or stroke in 10 years.
What they found is a greater predictive value with heart attack, said senior author Parag Joshi, MD, cardiologist and assistant professor of internal medicine.
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“In our study, there was a twice as high risk of heart attack than stroke at CAC levels at or above 100,” he said. “That goes for black, white and Spanish men and women.”
These results, Joshi said, could help providers decide how to aggressively treat patients who have never had a major heartbeat, but who also have other risk factors, such as high blood pressure or high cholesterol.
The team’s findings were based on the evaluation of CT scans of 7,042 participants from two large studies – the Multi-Ethnic Study of Atherosclerosis and the Dallas Heart Study. Based on these images, they divided the patients by the American Heart Association and American College of Cardiology category of calcium risk classes: 0, 1-99, and 100 and above. They also subdivided the participants by gender and race to calculate the different risk levels.
Based on their analysis, the team found that the risk of a heart attack was twice as high as a stroke for individuals with CAC scores greater than 100. For men in this group, the total 10-year-old heart attack was 12 percent – slightly higher at 14 percent for Spanish men – and it was 8 percent for women. Stroke risk in this group remained below 8 percent for all groups, but it was higher among women, blacks, and Spanish participants.
For individuals in the 1-99 CAC score group, the risk for both heart attack and stroke was below 6 percent. However, women in this cohort had a higher risk of stroke, while men had a higher risk of heart attack. Among individuals with a 0-score, the 10-year risk of heart attack or stroke was less than 2 percent.
It is possible, Joshi’s team suggested, that providers could use these findings from CT scans to inform their decisions about placing a patient on statin medications if the choice is not clear based on other factors, such as smoking history. , blood pressure, as cholesterol.
“If you think your patient needs to be on a statin, and your patient does not want to take it, this could be a good arbitrator for that,” he said. “Our findings also highlight some of the nuances between risk of heart attack and risk of stroke and how our patients may consider these two risks in their decisions.”
This study is the first to compare the predictive value for risks of heart attack and stroke. And, according to Leslee Shaw, Ph.D., professor of health services in radiology at the Dalio Institute of Cardiovascular Imaging at Weill Cornell Medicine, the data are robust enough to have a beneficial impact on clinical care.
“The present report represents an important validation of prior forecast results with CAC,” Shaw said in an accompanying editorial. “The comparison of coronary heart disease versus stroke risk based on CAC findings adds novelty to this report and represents important information to improve clinical decision-making regarding asymptomatic screening for atherosclerotic cardiovascular disease.”
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