Coronary angiography and intravascular ultrasound
Section snippets
Ntravascular ultrasound and coronary remodeling
IVUS has been extraordinarily useful in teaching us about the atherosclerotic disease process. We have learned that the traditional model of the disease, in which the plaque develops in the vessel wall over many years, gradually narrowing the lumen to produce symptoms, is not accurate. A more accurate model of atherosclerosis was originally described by Glagov et al,3 who showed that coronary “remodeling” enables patients to develop large atherosclerotic plaques without reduction in lumen size
Intravascular ultrasound, angiography, and the assessment of atherosclerotic disease: trial results
To illustrate, Figure 2 shows a typical patient with disease of the right coronary. This patient had a 95% obstruction treated successfully with a stent. However, although the left coronary system appears normal angiographically, using IVUS, multiple large plaques were identified throughout the artery. Although the entire artery was diffusely atherosclerotic, the angiogram remained normal because the lumen size was not altered. Thus, ultrasound can be used to provide very detailed images of the
Conclusion
In summary, IVUS has great potential as a means to accurately assess the atherosclerotic disease process. IVUS has the ability to demonstrate changes in plaque volume and plaque vulnerability over a relatively short period of time, with fewer patients than required for large morbidity and mortality endpoint trials. In the future, for IVUS to become a widely accepted surrogate, there needs to be a clear correlation between plaque volume by IVUS and cardiovascular events. If this correlation can
Discussion
Michael Cressman:
How did you figure in the potential for heterogeneity of a response of atherosclerotic lesions into sample size calculations for these studies?
Steven Nissen, MD (Cleveland, Ohio):
We picked total volume as the primary endpoint, but prespecified a series of secondary endpoints. For example, we take rolling 10-slice segments, then take the segments with the least atherosclerotic plaque, and that represents a defined endpoint. We take the 10 slices with the greatest atherosclerotic
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