Repeat Ultrasounds Predict Heart Risk
In High-Risk Patients, Repeating the Test Helped ID Those Who Had Heart Attacks, Strokes
Repeat Ultrasounds to Predict Heart, Stroke Risk continued...
Then they focused on the 574 patients with clearly demonstrable plaque buildup in the carotid arteries.
Six to nine months later, these patients all had repeat ultrasounds to measure changes in their plaque.
Reiter's team used the ultrasound images and a computer-assisted evaluation (called gray-scale median or GSM) to evaluate the darkness of the plaque and its density. If plaque appears darker, it has a low GSM and is thought to be unstable, more likely to rupture or burst.
"Our study is the first using repeat GSM testing for the assessment of an individual's cardiovascular risk," Reiter says.
Next, the researchers looked at whether the GSM levels had decreased -- considered a bad sign, reflecting unstable plaque -- or increased (a neutral to good sign) and whether the patient had had a cardiovascular event during the follow-up, for a median of three years.
Over a follow-up of slightly more than three years, the GSM levels decreased in 230 patients, or 40%, and increased in 344, or 60%. Those in the lowest GSM group, with the darkest plaque, were about 1.7 times more likely to have a cardiovascular event than those whose GSM went up the most, reflecting less dense plaque, during the follow-up.
Those whose GSM declined the most had a 68% survival rate at three years, compared to a 78% survival for those whose GSM increased.
The study is published in the September issue of the journal Radiology.
Ultrasound Predicts Stroke, Heart Attack: Second Opinions
Evaluating plaque at a single time point "is not as predictive an outcome as following it over time," says Nick Bryan, MD, a professor of radiology at the University of Pennsylvania, Philadelphia, and a spokesman for the American College of Radiology. That's a strength of the study, he says.
Another strength, he says: They used the ultrasound tests to predict cardiovascular events anywhere in the body, not just in the carotid artery.
So would a repeat ultrasound have helped Russert?
Too soon to say, Bryan says. "We don't know how well this [finding about repeat ultrasound] would apply to the general population," he says. In the study, the average age was 72. "This is not ready for clinical applications. It is a very interesting observation that will need a lot of follow-up."