Atherosclerotic plaque composition among patients with stenotic coronary artery disease on noninvasive CT angiography

Introduction: Multidetector computed tomographic angiography (MDCTA) has emerged as a promising noninvasive tool to rule out significant coronary artery disease (CAD). In addition, MDCTA also provides additional information about atherosclerotic plaque composition. In this study, we aim to assess whether differences in plaque composition exist across patients with varying degree of stenotic CAD disease. Methods: Four hundred and sixteen patients with chest pain or shortness of breath thought to be related to CAD (64% males, mean age: 61±13 years), with 61 (15%) reporting type 2 diabetes mellitus, who underwent contrast-enhanced MDCTA were studied. Enrolled patients had an intermediate pretest probability of obstructive disease. Results: Overall 51 patients (12%) had normal coronaries without evidence of plaque. In the remaining 365 patients, 45 (12%) and 83 (23%) were found to have stenosis 50-70% and at least 70% in at-least one coronary artery segment, respectively. Those with a higher degree of stenotic CAD showed significantly more coronary segments with exclusively calcified and mixed plaques. With increasing severity of CAD (<50 vs. 50-70% vs. >70% stenosis), the overall proportion of plaque burden was more likely to be mixed (18 vs. 38% vs. 44%) in nature as well less likely to be exclusively noncalcified (39 vs. 20 vs. 16%). Only two of 108 (2%) patients without any underlying calcification had significant CAD (stenosis ≥ 50%). Conclusion: Significant differences in plaque composition according to severity of CAD were observed in our study. Individuals with a higher likelihood of stenotic CAD were more likely to have higher underlying burden of exclusively calcified and mixed plaque. These findings should stimulate further investigations to assess the prognostic value of plaque according to their underlying composition.