OAK BROOK, Ill -- April 22, 2014 -- Imaging of the coronary arteries with computed tomography (CT) angiography provides an accurate assessment of arterial plaque and could have a dramatic impact on the management of patients with diabetes who face a high risk of myocardial infarctions (MIs) and other cardiovascular events.

The findings are published in the online edition of the journal Radiology.

Intravascular ultrasound can quantify non-calcified and calcified coronary artery plaque, but it is invasive and unsuitable for screening purposes, and coronary artery calcium (CAC) scoring with CT has limitations.

“Calcium scoring measures how much calcified plaque a person has, but it doesn’t measure the component that’s not calcified, and that’s the component that tends to be dangerous,” said João A. C. Lima, MD, Johns Hopkins University, Baltimore, Maryland.

Quantitative plaque analysis with coronary CT angiography has emerged as a viable screening option. Coronary CT angiography can capture the full anatomic map of the coronary arteries in a single heartbeat with low radiation dose and can provide a picture of the total amount of plaque throughout the arteries of the heart.

For the study, researchers evaluated coronary CT angiography in 224 asymptomatic patients with diabetes. Obese people with diabetes have a propensity for extensive and premature development of coronary artery plaque, making them an ideal study group for plaque assessment.

The researchers used measurements of coronary artery wall volume and length to determine a coronary plaque volume index (PVI) for each patient. The technique provided information well beyond the presence or absence of coronary stenosis, or narrowing. PVI was related to age, male gender, body mass index (BMI), and duration of diabetes. Younger individuals with a shorter duration of diabetes had a greater percentage of soft plaque.

“Coronary plaque volume index by coronary CT angiography is not only clinically feasible and reproducible in patients with diabetes, but it also provides a more complete picture of the coronary arteries that could be routinely applied in at-risk patients,” said David A. Bluemke, MD, National Institutes of Health (NIH), Bethesda, Maryland.

BMI was the primary modifiable risk factor associated with total and soft coronary plaque as assessed by coronary CT angiography.
“The results reinforce how important it is to evaluate BMI as a potential driver of overall diabetes,” said Dr. Bluemke. “As the only modifiable risk factor, obesity is an important target for managing patients with diabetes.”

Only about one-third of the coronary plaque in patients showed calcification, underscoring the widespread presence of non-calcified plaque.

The researchers will continue monitoring the patients from the study to better understand the value of coronary artery plaque assessment in predicting future cardiovascular events and to further define the role of plaque volume index versus CAC score.

Coronary CT angiography is likely to be valuable for other groups of patients at high risk for cardiovascular events, the researchers said, and may one day enable physicians to predict plaque development and treat it aggressively before PVI increases significantly.

SOURCE: Radiological Society of North America