Computed Tomographic Angiography Characteristics of Atherosclerotic Plaques Subsequently Resulting in Acute Coronary Syndrome

OBJECTIVES: In a computed tomographic (CT) angiography study, we identified the characteristics of atherosclerotic lesions that were associated with subsequent development of acute coronary syndrome (ACS). Background: The CT characteristics of culprit lesions in ACS include positive vessel remodeling (PR) and low-attenuation plaques (LAP). These 2 features have been observed in the lesions that have already resulted in ACS, but their prospective relation to ACS has not been previously described.

METHODS: In 1,059 patients who underwent CT angiography, atherosclerotic lesions were analyzed for the presence of 2 features: PR and LAP. The remodeling index, and plaque and LAP areas and volumes were calculated. The plaque characteristics of lesions resulting in ACS during the follow-up of 27 +/- 10 months were evaluated.

RESULTS: Of the 45 patients showing plaques with both PR and LAP (2-feature positive plaques), ACS developed in 10 (22.2%), compared with 1 (3.7%) of the 27 patients with plaques displaying either feature (1-feature positive plaques). In only 4 (0.5%) of the 820 patients with neither PR nor LAP (2-feature negative plaques) did ACS develop. None of the 167 patients with normal angiograms had acute coronary events (p < 0.001). ACS was independently predicted by PR and/or LAP (hazard ratio: 22.8, 95% confidence interval: 6.9 to 75.2, p < 0.001). Among 2- or 1-feature positive segments, those resulting in ACS demonstrated significantly larger remodeling index (126.7 +/- 3.9% vs. 113.4 +/- 1.6%, p = 0.003), plaque volume (134.9 +/- 14.1 mm(3) vs. 57.8 +/- 5.7 mm(3), p < 0.001), LAP volume (20.4 +/- 3.4 mm(3) vs. 1.1 +/- 1.4 mm(3), p < 0.001), and percent LAP/total plaque area (21.4 +/- 3.7 mm(2) vs. 7.7 +/- 1.5 mm(2), p = 0.001) compared with segments not resulting in ACS.

CONCLUSIONS: The patients demonstrating positively remodeled coronary segments with low-attenuation plaques on CT angiography were at a higher risk of ACS developing over time when compared with patients having lesions without these characteristics. D.J. Fluker Jersey

PMID: 19555840

Posted in Computed Tomography and tagged , , , , .

2 Comments

  1. Interesting article, demonstrating predictive value of low-attenuation and expansive remodeling of plaques assessed with MDCT for clinical events. As discussed by the authors, future studies will be necessary to evaluate the role of MDCT in the assessment of plaque vulnerability.

  2. Very interesting data obtained by a multivariate regression analysis in a large cohort of patients. The results from this study point in the direction of the “vulnerable plaque” theory. However, further investigations are required, such as correlative studies with IVUS as well as comparison with post ACS follow up images to determine the culprit lesions.

    Although I find this paper to be remarkable, I still struggle with the concept of plaque characterization when the spatial resolution is in the order of 0.6 mm and with the current 64 MDCT temporal resolution, both factors more than likely creating volume averaging artifact. Intuitively, positive remodeling may be more suitable and reproducible to assess using current state-of-the-art technology than plaque attenuation coefficient.

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