Background-Growth of atherosclerotic plaques is accompanied by neovascularization from vasa vasorum microvessels extending through the tunica media into the base of the plaque and by lumen-derived microvessels through the fibrous cap. Microvessels are associated with plaque hemorrhage and may play a role in plaque rupture. Accordingly, we tested this hypothesis by investigating whether microvessels in the tunica media, the base of the plaque, and the fibrous cap are increased in ruptured atherosclerotic plaques in human aorta. Methods and Results-Microvessels, defined as CD34-positive tubuloluminal capillaries recognized in cross-sectional and longitudinal profiles, were quantified in 269 advanced human plaques by bicolor immunohistochemistry. Macrophages/T lymphocytes and smooth muscle cells were defined as CD68/CD3-positive and ␣-actin-positive cells. Total microvessel density was increased in ruptured plaques when compared with nonruptured plaques (Pϭ0.0001). Furthermore, microvessel density was increased in lesions with severe macrophage infiltration at the fibrous cap (Pϭ0.0001) and at the shoulders of the plaque (Pϭ0.0001). In addition, microvessel density was also increased in lesions with intraplaque hemorrhage (Pϭ0.04) and in thin-cap fibroatheromas (Pϭ0.038). Logistic regression analysis identified plaque base microvessel density (Pϭ0.003) as an independent correlate to plaque rupture. Conclusions-Thus, neovascularization as manifested by the localized appearance of microvessels is increased in ruptured plaques in the human aorta. Furthermore, microvessel density is increased in lesions with inflammation, with intraplaque hemorrhage, and in thin-cap fibroatheromas. Microvessels at the base of the plaque are independently correlated with plaque rupture, suggesting a contributory role for neovascularization in the process of plaque rupture. (Circulation.
Background-A method is needed to identify nonstenotic, lipid-rich coronary plaques that are likely to cause acute coronary events. Near-infrared (NIR) spectroscopy can provide information on the chemical composition of tissue. We tested the hypothesis that NIR spectroscopy can identify plaque composition and features associated with plaque vulnerability in human aortic atherosclerotic plaques obtained at the time of autopsy. Methods and Results-A total of 199 samples from 5 human aortic specimens were analyzed by NIR spectroscopy.Features of plaque vulnerability were defined by histology as presence of lipid pool, thin fibrous cap (Ͻ65 m by ocular micrometry), and inflammatory cell infiltration. An InfraAlyzer 500 spectrophotometer was used. Spectral absorbance values were obtained as log (1/R) data from 1100 to 2200 nm at 10-nm intervals. Principal component regression was used for analysis. An algorithm was constructed with 50% of the samples used as a reference set; blinded predictions of plaque composition were then performed on the remaining samples. NIR spectroscopy sensitivity and specificity for histological features of plaque vulnerability were 90% and 93% for lipid pool, 77% and 93% for thin cap, and 84% and 89% for inflammatory cells, respectively. Conclusions-NIR
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