Plaque features by CCTA may give clues on ischemia

Coronary CT angiography (CCTA) may shed some light on lesions that cause ischemia, based on a study that compared atherosclerotic plaque characteristics by CCTA with lesion-specific ischemia by fractional flow reserve (FFR).

Hyung-Bok Park, MD, of New York-Presbyterian Hospital in New York City, and colleagues used data from the DeFACTO (Determination of Fractional Flow Reserve by Anatomic Computed Tomographic Angiography) study to explore the association between atherosclerotic plaque characteristics and ischemia by CCTA and FFR. The trial included 252 stable patients with suspected coronary artery disease who underwent CCTA, with FFR performed on 407 coronary lesions.

Park et al focused on atherosclerotic plaque characteristics by CCTA and their relationship to ischemia by FFR, looking at obstructive (50 percent or greater stenosis) and nonobstructive (less than 50 percent) lesions.

Every 5 percent increase in aggregate plaque volume carried a 50 percent increased risk of ischemia in obstructive lesions. Positive remodeling, low-attenuation plaque and spotty calcification were more prevalent in ischemic lesions. Those three characteristics and increasing numbers of them were associated with ischemia in both obstructive and nonobstructive lesions.

“[T]he absence of APCs [atherosclerotic plaque characteristics] identified lesions with a considerably lower prevalence of ischemia, even for highly stenotic coronary lesions,” they wrote. “To our knowledge, these data represent the first to examine the quantitative as well as qualitative relationship of APCs by coronary CTA for precise identification of coronary lesions that do versus do not cause ischemia.”

They noted that positive remodeling was a better predictor of ischemia in both obstructive and nonobstructive stenosis while the percentage of aggregate plaque volume and lesion length predicted ischemia in obstructive stenosis only.

“[G]iven the ability of %APV [percentage of aggregate plaque volume] and APCs to independently improve discrimination of ischemia-causing coronary lesions—coupled with their association with incident ACS [acute coronary syndrome] risk—consideration should be given to include these features in clinical reporting,” Park et al proposed.

The study was published in the January issue of the Journal of the American College of Cardiology: Cardiovascular Imaging.