|
||||||
|
|
|
|
|||||||||||
|
|||||||||||||
| ||||||||||||||||||||||||||||||||||||
Using computed tomography (CT) to image the calcification of coronary arteries may be a valuable way of assessing cardiac risk—and more accurate than traditional means—according to researchers presenting at the 2006 Cardiometabolic Health Congress, held October 19–21 in Boston.
Although the risk of coronary artery disease (CAD) mortality and morbidity is two to four times greater in people with diabetes, the tools available to clinicians to accurately assess CAD in people with diabetes are lacking, says Paolo Raggi, MD, of Tulane University School of Medicine in New Orleans.
"Diabetic patients... have it worse, with higher mortality after coronary artery bypass graft surgery and PCTA [percutaneous transluminal angioplasty]," Raggi says.
The usual methods of assessing coronary artery health, based on detecting obstructed arteries, often are not useful in people with diabetes because their acute coronary syndrome often occurs without stenosis.
With all the tools available in a well equipped hospital—ECG, stress testing, angiography, and other forms of diagnostic imaging—exhaustive evaluation of people with diabetes is likely to generate a costly number of false-positive results.
CAD frequently is silent in people with diabetes, with disease processes well advanced before the condition is apparent. In many cases, the first clue is myocardial infarction or sudden death.
"We're doing more and more testing, using more and more modalities, and still patients are dying at our hands," Raggi says.
Some researchers suggest the use of surrogate markers of cardiovascular disease for people with diabetes. High levels of proteinuria, for example, are linked to a much higher incidence of cardiovascular mortality, Raggi says. Glycated hemoglobin (A1C) also is associated with cardiovascular outcomes, and the presence of retinopathy nearly doubles the probability that CAD will be identified with nuclear stress testing.
CALCIUM IMAGING
An answer to the diagnostic dilemma may be found in calcium, a constituent found in all atherosclerotic plaques. In a 2005 paper, Raggi and colleagues explained how coronary artery calcium (CAC) imaging, along with myocardial perfusion testing, is used to assess cardiovascular risk in people with diabetes.1
CAC scoring is a noninvasive way to obtain information about the location and extent of calcified plaque in the coronary arteries. With CT, the mineralized calcium deposits can be visualized clearly. The score is based on the size, density, and volume of the atherosclerotic plaque.
A diabetic patient's CAC score correlates very closely with the incidence of diabetes complications and is a good predictor of the progression of CAD, Raggi says.
"There is a loose correlation between how much calcium is present in coronary arteries and how much stenosis," he says. "But we don't do calcium screening to predict stenosis. We do calcium screening to measure the burden of atherosclerotic disease."
Although not perfect, CAC scoring may take its place in the clinicians'
toolbox for diagnosing people with cardiovascular complications of diabetes.
It can be done with several types of CT devices available in most diagnostic
radiology departments. Cost for CAC scoring is about one-tenth the cost of
coronary angiography—$4,000 for angio versus $350–$400 for CAC
scoring. 
References
CiteULike 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
| ||||||||||||||||||||||||||||||||||||
|
||||||
|
| DOC News | Diabetes | Diabetes Care | Clinical Diabetes | Diabetes Spectrum |
