Plaque rupture relationship to plaque composition in coronary arteries. A 320-slice CT angiographic analysis

BackgroundCoronary thrombosis leading to myocardial ischemia is now recognized as a diverse process arising from plaque rupture, erosion, or calcified nodules. These vulnerable plaques may not always cause significant stenosis of the artery, and therefore be missed on an invasive catheter angiogram (ICA). The advent of multidetector computed tomography (MDCT) imaging of the walls of the coronary artery has opened a unique window to these vulnerable plaques. Differentiation of calcified plaques from soft plaques presents no challenge on CT. Further characterization of the plaque into a ruptured plaque is possible by demonstration of discontinuity of the plaque surface and contrast pooling within the plaque substance.PurposeTo study the relation between coronary artery plaque rupture and plaque composition.Materials and methods500 patients referred for coronary CT angiogram between 2008 and 2013, who had plaque thicknesses of 2 mm or more, were included in the study. The plaques were divided into totally calcified, mixed, and soft categories. The totally calcified plaques were excluded from the study as none of these showed signs of plaque rupture. A total number of 2667 mixed and soft plaques were included in the study.Results52% of the total plaques were ruptured and 48% not ruptured. Of the ruptured plaques, 96.9% were mixed type and only 3.7% were soft. And of the non-ruptured plaques, 96.3% were soft and only 3.1% mixed (p < 0.0001).ConclusionThis study reveals that plaque rupture is significantly associated with mixed plaques containing soft and calcific areas rather than purely soft plaques.