Atherosclerotic Plaque Characteristics by CT Angiography Identify Coronary Lesions That Cause Ischemia

Abstract

Objective We evaluated the association between atherosclerotic plaque characteristics (APCs) by coronary CT angiography (CT) and lesion ischemia by fractional flow reserve (FFR). Background FFR is the gold standard for determining lesion ischemia. While APCs by CT—including aggregate plaque volume % (%APV), positive remodeling (PR), low attenuation plaque (LAP) and spotty calcification (SC)—are associated with future coronary syndromes, their relationship to lesion ischemia is unclear. Methods 252 patients (17 centers, 5 countries) [mean age 63 years, 71% males] underwent CT, with FFR performed for 407 coronary lesions. CT was interpreted for < and >50% stenosis, with the latter considered obstructive. APCs by CT were defined as: (1) PR, lesion diameter/reference diameter >1.10; (2) LAP, any voxel <30 HU; and (3) SC, nodular calcified plaque <3 mm. Odds ratios (OR) and net reclassification improvement (NRI) of APCs for lesion ischemia, defined by FFR <0.8, were analyzed. Results By FFR, ischemia was present in 151 lesions (37%). %APV was associated with a 10% increased risk of ischemia per 5% additional APV. PR, LAP and SC were associated with ischemia, with a 3-5 times higher prevalence than in non-ischemic lesions. In multivariable analyses, a stepwise increased risk of ischemia was observed for 1 [OR 4.5, p<0.001)] and ≥2 (OR 13.2, p<0.001) APCs. These findings were APC-dependent, with PR (OR 5.4, p<0.001) and LAP (OR 2.2, p=0.028) associated with ischemia, but not SC. When examined by stenosis severity, PR remained a predictor of ischemia for all lesions, while %APV and LAP were associated with ischemia for only >50% but not for <50% stenosis. Conclusions %APV and APCs by CT improve identification of coronary lesions that cause ischemia. PR is associated with all ischemia-causing lesions, while %APV and LAP are only associated with ischemia-causing lesions >50%.

Quantifying Plaque Burden and Morphology Using Coronary Computed Tomography Angiography to Predict Coronary Physiology

“…Using machine learning, they showed that a composite risk score integrating age, sex, and CT-based plaque characteristics (noncalcified plaque) was a better discriminator of vessels with impaired CFR than the stenosis severity alone. These results are consistent with a recent study by Park et al 11 demonstrating that total plaque volume and an aggregate model, including plaque volume, lesion length, and low attenuation plaques on coronary CTA, improved identification of stenosis associated with abnormal invasive fractional flow reserve.…”

Progression of coronary artery calcification at the crossroads: sign of progression or stabilization of coronary atherosclerosis?

“…Future discrimination between these two completely different sources of coronary calcium might become a major breakthrough in CAC imaging, since spotty calcifications have been recognized as a marker of high risk plaques (81,82).…”

Impact of plaque characteristics on the degree of functional stenosis

“…Recently this relation was also depicted using CCTA. In a study that included 252 stable patients undergoing both CCTA and ICA with FFR, Park et al were able to document an association between certain CCTA atherosclerotic plaque characteristics (APCs) and the presence of ischemia by invasive FFR (31). In their study, lesion length, positive remodelling (index ≥1.1), and the presence of low attenuation plaque (<30 HU) were independent predictors of ischemia by invasive FFR.…”