CT Scans Can Spot Blocked Arteries

Nov. 27 -- WEDNESDAY, Nov. 26 (HealthDay News) -- Expensive, high-tech CT devices that produce 64-slice images of arteries are almost, but not quite, as good as the standard method of detecting and gauging blood vessel blockages, a study finds.

Therefore, "multidetector CT angiography cannot replace conventional coronary angiography at present," concludes a report in the Nov. 27 issue of the New England Journal of Medicine.

But if that is so, experts ask, why is Medicare continuing to pay for these pricey CT exams?

"There is no evidence that they are of benefit to patients," said Dr. Rita F. Redberg, professor of medicine at the University of California, San Francisco, co-author of an editorial in the journal. "In general, there should be evidence of benefit before there is widespread use," she said.

Nevertheless, the study's lead author said the scans may have a place in cardiovascular care.

"Our study shows they do have value, because they have a high degree of diagnostic accuracy to identify patients with tight heart blockages," said Dr. Julie M. Miller, assistant professor of medicine at Johns Hopkins University. "Having the scan is a noninvasive procedure, and that is very attractive. Patients do not undergo the risk, even though it is small, of angiography."

Angiography, which requires insertion of a slim catheter tube into the blood vessels, is the typical way physicians gauge the degree of artery blockage to determine whether treatment is necessary. "Our paper shows for the first time that 64-CT scans can identify patients who need to go on to angioplasty and bypass procedures," Miller said. "It has diagnostic accuracy compared to other tests, such as stress testing. They create more invasive catheterizations than are needed than if the 64-CT test is used."

The study of 291 people with suspected coronary artery blockages was done at nine U.S. medical centers. They underwent both 64-CT and conventional coronary angiography.

The CT scans accurately predicted 84 percent of the treatment procedures that were required, compared to 82 percent accuracy for angiography.