MDCT angiography assists in measuring plaque vulnerability in diabetic patients
BOSTON—The majority of atherosclerotic plaque in patients with type 2 diabetes mellitus had calcification; however, among patients with significant coronary artery disease, mixed plaque is more commonly observed, according to a poster presentation at the American Society of Nuclear Cardiology (ASNC) conference last week.

It is commonly accepted that patients with diabetes mellitus (DM) have a higher risk of coronary artery disease (CAD) and are likely to have a higher underlying atherosclerotic burden. However, the researchers said that the atherosclerotic plaque composition in these patients is not studied.

Uzoma N. Ibebuogu, MD, from the Medical College of Georgia in Augusta, along with colleagues from Massachusetts General Hospital in Boston and Los Angeles Biomedical Research Institute at Habor-UCLA in Torrance, Calif., evaluated the plaque burden, morphology and distribution in type 2 DM patients using multi-detector CT angiography (MDCTA) in their ongoing clinical trial.

Investigators studied 40 symptomatic diabetic subjects (average age of 63, 55 percent male), who underwent contrast-enhanced MDCTA. They noted that the enrolled patients had an intermediate pre-test probability of obstructive CAD.    

According to the researchers, 83 percent of the subjects had at least one segment with any plaque, 69 percent had detectable coronary artery calcification (CAC) and 36 percent had CAC ? 400.

Among individuals with any plaque, Ibebuogu and colleagues found that the mean number of segments involved was 5.7; the mean number of segments with exclusively non-calcified, calcified and mixed plaques were 1, 2.7 and 2 segments, respectively.

During his presentation at ASNC, Ibebuogu noted that thin-cap fibroatheromas (TCFA), a virtual histology intravascular ultrasound (from Volcano) high-risk plaque feature considered as a precursor of coronary plaque rupture, have been shown to occur more frequently in mixed plaques as compared with noncalcified and calcified. He noted that the researchers only used MDCTA to assess the patients, adding that the technologies provide a means of properly assessing plaques.

Twelve patients had at least one coronary segment with significant stenosis (luminal narrowing ? 50 percent).

The researchers found that type 2 DM patients with significant stenosis were more likely to have a mixed plaque composition (39 vs. 28 percent), and less likely to be exclusively noncalcified plaque alone (17 vs. 26 percent) when compared to those without significant stenosis. However, the authors observed no difference in the respective proportion of exclusively calcified plaque (44 vs. 46 percent).

Ibebuogu and colleagues concluded that the prognostic value of the different atherosclerotic plaque morphologies on MDCT in higher risk DM patients needs to be assessed in larger, prospective studies.