Subclinical disease detected on imaging predicts death, report investigators who show that plaque burden found on 3D vascular ultrasound and coronary artery calcium on CT were better predictors of death than traditional risk factors.
The work not only highlights the importance of early detection, but it also has clinical implications, said Valentin Fuster, MD, president of the Mount Sinai Fuster Heart Hospital in New York. “It’s going to change things,” he said. “What I believe is going to happen is that we will begin to evaluate people with risk factors at age 30 using imaging. Today, we evaluate people at age 50 using clinical practice guidelines.”
Fuster’s team developed 3D vascular ultrasound to assess plaque burden and applied it in a prospective cohort study known as BioImage. The researchers assessed 6102 patients in Chicago, Illinois, and Fort Lauderdale, Florida, using 3D vascular ultrasound of the carotid artery and another well-established modality — coronary artery calcium, determined by CT.
Participants had no cardiovascular symptoms, yet their plaque burden and calcium scores at the beginning of the study were significantly associated with death during the 15 years of follow-up, even after taking risk factors and medication into account. The results are published in the Journal of the American College of Cardiology.
“Now, there is no question that subclinical disease on imaging predicts mortality,” said Fuster.
David Maron, MD, a preventive cardiologist at the Stanford University School of Medicine, calls the finding “very important.”
“The presence of atherosclerosis is powerful knowledge to guide the intensity of therapy and to motivate patients and clinicians to treat it,” says Maron, who is the co-author of an accompanying editorial and was not involved in the study.
Predicting Risk Early
The research also showed that the risk for death increases if the burden of plaque in the carotid artery increases over time. Both plaque burden shown on 3D vascular ultrasound and coronary artery calcium on CT were better predictors of death than traditional risk factors.
Maron says recent studies of younger populations, such as Progression of Early Subclinical Atherosclerosis (PESA) and Coronary Artery Risk Development in Young Adults (CARDIA), show that “risk factors at a young age have much more impact on arterial disease than when we measure risk factors at older age.” The CARDIA study showed signs of atherosclerosis in patients as young as in their twenties. This paradigm shift to early detection will now be possible thanks to technological advances like 3D vascular ultrasound.
Maron says he agrees with screening earlier in life. “The risk of having an event is related to the plaque burden and the number of years that a patient has been exposed to that burden. The earlier in life we can identify the burden to slow, arrest, or even reverse the plaque, the better.”
Maron points out that the study looked at an older population and did not include information on cause of death. While a study of younger people and data on cardiac causes of death would be useful, he says the study’s conclusions remain significant.
3D Vascular Ultrasound vs Coronary Artery Calcium
While both imaging methods in the study predicted death better than cardiovascular risk factors alone, each option has advantages.
For coronary artery calcium, “there’s a huge amount of literature demonstrating the association with cardiovascular events, there’s a standardized scoring system, there are widespread facilities for computed tomography, and there is not a lot of variability in the measurement — it’s not dependent on the operator,” says Maron.
But there is one drawback. The scoring system –— the Agatston score — can paradoxically go up following aggressive lowering of low-density lipoprotein cholesterol. “Once coronary calcium is present, it is challenging to interpret a repeat scan because we don’t know if the increase in score is due to progression or increasing density of the calcium, which is a sign of healing,” says Maron.
Vascular ultrasound avoids this problem and can also identify early noncalcified plaques and monitor their progression before they would appear on CT. Furthermore, the imaging does not add to lifetime radiation dose, as CT does, Fuster said.
3D ultrasound technology will soon be available in an inexpensive, automated, and easy-to-use format, he explains. Fuster envisions a scenario in which a nurse in a low-income country, using a cell phone app, will be able to assess atherosclerosis in a patient’s femoral artery. “In less than 1 hour, we can predict disease much more rigorously than with risk factors alone,” he says. “I think this is very exciting.”
Progression Increases Risk
Finding any atherosclerosis means an increased risk for death, but a greater burden or amount of atherosclerosis increases that risk, said Fuster. Progression of atherosclerosis increases risk even further.
The study looked at changes in atherosclerosis burden on vascular ultrasound in a subset of 732 patients a median of 8.9 years after their first test. Those with progression had a higher risk for death than those with regression or no atherosclerosis. “Progression is much more significant in predicting mortality than atherosclerosis findings alone,” Fuster said.
Maron says this finding points to “two great values from noninvasive imaging of atherosclerosis.” Not only does imaging detect atherosclerosis, but it can also characterize the burden and any calcification. Further, it allows doctors to monitor the response to interventions such as lifestyle changes and medical therapy. “Serial imaging of plaque burden will really enhance the management of atherosclerosis,” says Maron. “If we discover that someone is progressing rapidly, we can intensify therapy.”
He says imaging results also provide needed motivation for both clinicians and patients to take action that would prevent the deaths that result from atherosclerosis.
