August 19 (HealthDay News) -- Inexpensive ultrasound imaging may be a simple way to help determine who's at high risk for a heart attack or other cardiovascular issues, a new study says.

Researchers conducted ultrasound imaging on the carotid arteries -- the two vessels that supply blood to the head and neck -- of 1,268 patients who were asymptomatic but at high risk for cardiovascular disease. They found that nearly half the patients had carotid artery disease.

The findings are published in the September issue of the journal Radiology.

"Determining the degree of stenosis, or how much the artery has narrowed, is insufficient to predict patient risk," lead researcher Dr. Markus Reiter, of the Department of Angiography and Interventional Radiology at Medical University Vienna in Austria, said in a news release issued by the journal. "We know that the majority of cardiovascular and cerebrovascular events occur in patients whose blood vessels are less than 70 percent narrowed."

Reiter and his team used ultrasound images and computer-assisted gray scale median (GSM) measurements to determine the density of the plaque lining the carotid arteries. Plaques that appear dark on ultrasound images and have a low GSM level are thought to be associated with an increased risk for clinical complications and seem to represent unstable plaques, which are more likely to rupture or burst.

Follow-up ultrasounds done several months later showed that the conditions of the arteries in 40 percent of the patients had grown worse. Of those, 37 percent had a major cardiovascular event, such as a heart attack, stroke or coronary artery bypass, within three years of the second ultrasound.

Of the others whose ultrasounds appeared better on the follow-up, 28 percent experienced a major adverse cardiovascular event.

The authors noted their findings showed that vulnerable plaque in the carotid artery indicated not only an increased risk of stroke downstream, but also was linked to cardiovascular disease progressing elsewhere in the patient.

While more studies are needed, Reiter said serial ultrasound exams may be a noninvasive way to identify whether vulnerable plaques exist and improve the effectiveness of various therapies.

"This technique will give us additional information to use in selecting patients that need aggressive treatment," he said.

SOURCE: Radiological Society of North America, news release, Aug. 19, 2008