Differences in Plaque Composition and Distribution in Stable Coronary Artery Disease Versus Acute Coronary Syndromes; Non-invasive Evaluation with Multi-slice Computed Tomography

Background: Plaque composition rather than degree of luminal narrowing may be predictive of acute coronary syndromes (ACS). The purpose of the study was to compare plaque composition and distribution with multi-slice computed tomography (MSCT) between patients presenting with either stable coronary artery disease (CAD) or ACS.

Methods: MSCT was performed in 22 and 24 patients presenting with ACS or stable CAD, respectively. Coronary lesions were classified as calcified, non-calcified or mixed while signal intensity (SI) was measured.

Results: In patients with stable CAD, the majority of lesions were calcified (89%). In patients with ACS, less calcifications were observed with a greater proportion of non-calcified (18%) or mixed (36%) lesions (P<0.001). Accordingly, mean SI of plaques was significantly less in ACS (320+/-201 HU versus 620+/-256 HU in stable CAD, P<0.001). Dividing lesions in the ACS group according to culprit versus non-culprit vessel location resulted in no significant difference in average SI between these two groups while still lower as compared to stable CAD (P<0.001).

Conclusions: In patients with ACS, significantly less calcifications were present as compared to stable CAD. Moreover, even in non-culprit vessels, multiple non-calcified plaques were detected, indicating diffuse rather than focal atherosclerosis in ACS.