By Charlene Laino, AuntMinnie.com contributing writer

December 1, 2010 -- CHICAGO - Using CT angiography (CTA), researchers have found that African-American patients have more noncalcified plaque in their coronary arteries than Caucasian patients. The study results were reported at the RSNA annual meeting being held this week in Chicago.

In the study of 301 patients, 64% of African-American patients had this unstable plaque, compared with 41% of Caucasians (p < 0.001).

African-Americans also had less calcified plaque than whites, reported John Nance Jr., MD, a researcher in the department of radiology and radiological sciences at the Medical University of South Carolina in Charleston.

"Calcium scores of African-Americans may under-represent the true extent of atherosclerotic disease," Nance told a news briefing.

Population-based studies consistently demonstrate lower burdens of coronary calcification among blacks, despite an increased risk of cardiovascular events. It's been hypothesized that the increased risk is due to an abundance of noncalcified plaque, which has been shown to be more likely to rupture than stable, calcified disease, he said.

The new study involved patients who underwent noncontrast calcium scoring and contrast-enhanced coronary CT angiography for acute chest pain (33% male; mean age, 55) at the medical center. One hundred and fifty of the subjects were African-American.

Among the findings:

  • Caucasian patients were significantly more likely to have calcified plaque than blacks, at 45% versus 26% (p = 0.001).
  • African-Americans had an increased noncalcified plaque volume compared to whites (median 2.2 mL versus 1.4 mL, p < 0.001).
  • In a multivariate analysis adjusted for diabetes, high cholesterol, body mass index, and other risk factors, African-Americans were 2.45 times more likely to have noncalcified plaque than Caucasians (95% confidence interval: 1.52-4.04).

"Not all plaque is created equal," Nance said.

While an abundance of noncalcified plaque may help explain why blacks have a higher burden of cardiovascular disease despite lower coronary calcium scores, the reasons are unclear, he said.

African-Americans have lower rates of osteoporosis, Nance said, adding that different ethnicities have different rates of calcium metabolism.

Calcium metabolism "could play some role," he said.

The findings imply that patients who have more of these soft plaques should be aggressively treated with lifestyle and dietary modifications, lipid-lowering drugs, and blood pressure medications.

Asked to comment on the findings, David Hovsepian, MD, chief of interventional radiology at Stanford University Medical Center in Stanford, CA, called for prospective controlled trials.

Atherosclerosis is "not just about calcium. Coronary calcium can underestimate the burden of disease," he said.

By Charlene Laino
AuntMinnie.com staff writer
December 1, 2010

Left ventricular mass associated with stroke risk in African Americans, October 9, 2007

Copyright © 2010 AuntMinnie.com


Last Updated np 5/19/2011 11:53:36 AM

6 comments so far ...
12/2/2010 12:49:14 AM
telemed
This group is loose with the facts. Noncalcified plaque does not necessarily equate to "unstable" plaque. In addition, it is an oversimplification to depict calcified plaque as "stable".

It has been known for many years and confirmed by MESA that African Americans have lower calcium scores...they also have more LV hypertrophy. So, the reason for increased event rates is not clear...and certainly not proven by this report.


12/2/2010 7:39:48 AM
MDCT
Calcified plaque may not be stable, but it is more likely to be. However, calcified plaque is not a good thing, as in general, the more calcified plaque you have, the more noncalcified plaque burden you will have.

I agree that you cannot tell whether noncalcified plaque is unstable or not. However, having more noncalcified plaque is probably not a good thing.

12/2/2010 10:09:18 AM
Noah''sArk
good comments
Quote from
ORIGINAL: telemed

This group is loose with the facts. Noncalcified plaque does not necessarily equate to "unstable" plaque. In addition, it is an oversimplification to depict calcified plaque as "stable".

It has been known for many years and confirmed by MESA that African Americans have lower calcium scores...they also have more LV hypertrophy. So, the reason for increased event rates is not clear...and certainly not proven by this report.


12/2/2010 11:05:10 AM
telemed
As someone involved clinically and in research in atherosclerosis imaging for 15 years, i am in general agreement with MDCT. It was the work of Rumberger that originally showed that calcified plaque represents the tip of the atherosclerotic iceberg---and the more calcified plaque, the higher the likelihood for plaque that is vulnerable to rupture.

It is important for imagers not to automatically declare 'non-calcified" lesions on CTA as "unstable".

In fact most "unstable plaque" has been shown to have a mixture of calcium and uncalcified plaque...so according to Rumberger and histopathologists like Erling Falk, "calcium is neither a marker of stable or unstable plaque"

12/2/2010 11:30:16 AM
MDCT
I think that unfortunately many imagers don't understand atherosclerosis very well. So your contributions are helpful Telemed.
 
You are correct in that unstable plaque usually contains both calcified and noncalcified plaque. Plaques with large amounts of calcium tend to be more stable though - for example, they typically do not demonstrate FDG uptake which is suggestive of macrophage infiltration. Unfortunately techniques like PET and MRI which are more specific for unstable plaque cannot be reasonably applied in a cost-effective manner. CT based techniques like densitometry don't really work.
 
My own opinion is that non-imaging markers, such as CRP, will be the most widely used in this arena.
 
 
 
 



Sponsored By

|| About || Advertising || AuntMinnieCME.com || Bookstore || Breast MRI || Career Center || Case of the Day || Communities || Conferences || Contact Us || ECR News 2014 || Education || Equipment Classifieds || Europe || Facebook || Forums || Home || Links || Marketplace || Middle East || Mobile || Molecular Breast Imaging || New Installations || News in Brief || People in the News || Privacy Policy || RSNA News 2013 || Reference || Salary Survey Results || Trends in Radiology || Twitter || Vendor Connect || Webinars || XML/RSS ||

Copyright © 2019 AuntMinnie.com. All Rights Reserved.