AMSTERDAM, THE NETHERLANDS — Coronary artery calcium (CAC) density was inversely related to 10-year risk of cardiovascular disease and coronary heart disease in an extended analysis of individuals in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort who had calcium deposits in their coronary arteries detected by computed tomography, new research shows[1].
For this reason, the CAC-density component of the Agatston score is an especially important predictor of cardiovascular risk, said Dr Michael Criqui(University of California, San Diego), presenting the results here at the International Symposium on Atherosclerosis 2015.
"Our new conclusion is that not only is density protective at any given level of CAC, but . . . even if you have a lot of CAC, it's better to have it all calcified," he said.
These findings suggest CAC-density values could be especially useful to determine preventive therapy for patients at intermediate risk of a cardiovascular disease event. That is, for patients with a 10% to 20% risk of developing cardiovascular disease within 10 years, "it would be helpful to know their CAC-[density] score, because if it is [low] that pushes you toward aggressive treatment, and if it is [high], you might back off," Criqui told heartwire from Medscape.
"Dense Plaque Is the Safe Plaque"
Agatston scores, which have been used for the past 20 years or so, may have it "backward," since the components rather than the final score might be more useful for risk stratification, Criqui said. In a previous study in same cohort, the researchers showed that "if you consider CAC volume and density separately, you get a much stronger risk prediction" than the Agatston score, according to Criqui. In that study, reported by heartwire when it was presented and published in 2013, the group showed that during a median follow-up of 7.6 years CAC density was inversely related to cardiovascular disease risk.
In the current study, the researchers analyzed data from 1964 men and 1434 women in the MESA cohort who had had CAC scores greater than 0 at baseline and followed them for a median of 10 years. There were 264 coronary heart disease events and 126 cardiovascular events (noncoronary), approximately 50% more events than in the earlier study.
CAC volume was associated with an increased risk of coronary heart disease, with a hazard ratio of 1.83 for each standard deviation of CAC volume. In contrast, CAC density was associated with a decreased risk of coronary disease, with a hazard ratio of 0.71 for each standard deviation of CAC density (P<0.001 for both). Similarly, the hazard ratio for cardiovascular disease was 1.68 for each standard deviation of CAC volume and 0.75 for each standard deviation of CAC density (P<0.001 for both).
Patients with high CAC density were less likely to have coronary or cardiovascular events, and vice versa—whether they had a little or a lot of plaque. "It is kind of remarkable that the calcium volume and density alone outweighed the entire the [American College of Cardiology/American Heart Association] atherosclerotic cardiovascular disease risk score," Criqui said.
Ongoing research from this group and others should help clarify plaque findings that are associated with increased risk.
For example, another study in the MESA cohort suggests that the number of arteries involved, at any level of total arterial plaque, is additionally predictive of risk of coronary or cardiovascular disease, Criqui said. Research findings are mixed as to whether plaque in certain coronary arteries is more damaging, although some research suggests that "the left main coronary artery is the 'widow maker,' " he added. Other research suggests that the spatial distribution of plaque has further predictive value, and a simple scoring algorithm might be as good as a complex one, he said.
Session cochair Dr David Waters (University of California, San Francisco) wanted to know whether the current study showed that "it's not the plaque that's dense that actually gives you the event." Criqui confirmed this, saying, "Yes, the dense plaque is the safe plaque; it's stable." Moreover, evidence from other studies shows that a patient whose lesions are all calcified is part of a relatively low-risk group compared with those who have some calcified lesions or no calcified lesions but a lot of plaque, he added.
Criqui said that preventive cardiologists generally agree that low-risk patients can be "left alone" and high-risk patients need aggressive therapy, but intermediate-risk patients may warrant more aggressive therapy if their coronary calcium score is poor. The current line of research should ultimately help with treatment decisions in intermediate-risk patients, he suggested.
Criqui had no relevant financial relationships.
Heartwire from Medscape © 2015 Medscape, LLC
Cite this: The Denser the Coronary Plaque, the Lower the CVD Risk, New MESA Analysis Shows - Medscape - May 27, 2015.
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