London: Cheaper alternatives like ultrasound imaging can help identify those at high risk for a heart attack or other cardiovascular conditions, according to a study.

Researchers performed ultrasound imaging on the carotid arteries of 1,268 patients who were asymptomatic but at high risk for cardiovascular disease.

Of those, ultrasound determined that 574 patients had carotid artery disease, by the amount of plaque built up in the two vessels that supply blood to the head and neck.

Each of those patients had a second ultrasound exam six to nine months later to measure changes in plaque lined arteries.

"Determining the degree of stenosis, or how much the artery has narrowed, is insufficient to predict patient risk," said lead researcher Markus Reiter, of Medical University in Austria.

"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 suggested to be associated with an increased risk for clinical complications and seem to represent unstable plaques, which are more likely to rupture or burst.

The study's follow-up ultrasounds revealed that GSM levels had decreased in 230 (40 percent) of the patients. Of those, 85 (37 percent) experienced a major adverse cardiovascular event within three years of the second ultrasound.

Examples of these events include heart attack, stroke, coronary artery bypass, surgery or other intervention.

In 344 (60 percent) of the patients, ultrasound GSM levels had increased between the baseline and follow-up ultrasound examinations. Of those patients, 92 (28 percent) experienced a major adverse cardiovascular event.

"Patients with a reduction in GSM levels from their baseline ultrasound to the follow-up ultrasound exhibited a significantly increased risk for near-future adverse event compared to patients with increasing GSM levels," said Reiter.

Although additional studies are needed, Dr. Reiter said "this technique will give us additional information to use in selecting patients that need aggressive treatment," he said.

These findings will be published in the September issue of Radiology. IANS