Multislice Computed Tomographic Coronary Angiography for Quantitative Assessment of Culprit Lesions in Acute Coronary Syndromes

Background: We studied the characteristics of low-density plaque (LDP) burden in patients with acute coronary syndrome (ACS), using 64-slice computed tomography (CT) assessment. Though several CT plaque features such as positive remodelling, adjacent spotty calcification or the presence of LDP have been demonstrated to be associated with unstable plaques, it is still unknown whether their severity and extent present any differences between different types of ACS. Methods: In 45 subjects with ACS (22 unstable angina and 23 non-ST-elevation myocardial infarction [NSTEMI]), 118 coronary plaques were evaluated using a CT multislice 64 assessment including the burden with atheroma having a CT density below 30, 60, or 100 Hounsfield units (HU), remodelling index and spotty calcification. Results: Culprit lesions tend to be larger in volume (111.11 mm(3) vs 62.25 mm(3); P < 0.0001), have a higher remodelling index (1.27 vs 1.01; P < 0.0001), and present a significantly larger LDP with a density < 30 HU (23.3 mm(3) vs 7.6 mm(3); P < 0.0001) or < 60 HU (33.4 mm(3) vs 16.9 mm(3); P < 0.0001) than nonculprit lesions. The presence of a plaque more than 20 mm3 in volume with a CT density < 30 HU (P = 0.0009) and the presence of all 3 markers of plaque vulnerability (LDP, spotty calcifications or positive remodelling) (P = 0.01) significantly correlated with the presence of an NSTEMI. Conclusions: Culprit lesions demonstrated larger plaque volumes, a higher burden with low-density cores, and more intense remodelling than nonculprit lesions, whereas culprit lesions associated with NSTEMI showed a higher burden with lower density cores than those associated with unstable angina.