Abstract 18309: Integration of Quantitative Measures of Stenosis Severity With Morphologic Atherosclerotic Plaque Characteristics Improves Discrimination of Coronary Lesions that Cause Ischemia: Results from a Prospective Multicenter International Trial

Abstract

Background: Beyond stenosis severity, coronary computed tomographic angiography (CCTA) enables morphologic evaluation of atherosclerotic plaque characteristics (APCs), including aggregate plaque volume, positive arterial remodeling (PR), low attenuation plaque (LAP) and spotty calcification (SC), features associated with global myocardial ischemia and acute coronary syndromes. We determined whether the combination of stenosis severity plus APCs would improve the discrimination of coronary lesions that cause ischemia. Method: 252 patients from 17 centers in 5 countries [mean age 63 years, 71% males] underwent CCTA and invasive angiography, with invasive fractional flow reserve (FFR) performed for 407 coronary lesions. Stenosis severity was determined by luminal diameter reduction (%DS). Aggregate plaque volume (APV) was defined as the plaque volume from ostium to distal end of the lesion, with APV percent (%APV) defined as APV divided by total vessel volume. Other APCs by CCTA 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. Lesion ischemia was defined by invasive FFR ≤0.8, which was employed as the reference standard. Results: Coronary stenosis severity and APCs demonstrated good discrimination for lesion ischemia: %DS, (Area under the receiver operating characteristics curve [AUC] of 0.72 (95% CI 0.68-0.77), APV (AUC 0.69, 95% CI 0.64-0.73), and %APV (0.75, 98% CI 0.70-0.79). Over %DS alone, the addition of %APV improved the discrimination of lesion-specific ischemia (0.79, 95% CI 0.75-0.83, p<0.001), with further improvement with increasing APC number (0.86, 95% CI 0.82-0.89, p<0.001) [Figure]. Conclusion: In this prospective multicenter international study, the combination of quantitative measures of stenosis severity with morphologic features of atherosclerotic plaque by CCTA resulted in improved discrimination of coronary lesion-specific ischemia.