Intravascular Ultrasound in the Drug-Eluting Stent Era
Gary S. Mintz, MD*,a,* and
Neil J. Weissman, MD ,b
* Cardiovascular Research Foundation, New York, New York
Washington Hospital Center, Washington, DC.
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Figure 1 This illustration shows the percentage intimal hyperplasia volume from trials of drug-eluting stents. The drug and its carrier vehicle (polymeric or nonpolymeric) and the name of the trial are shown. The time point of the intravascular ultrasound analysis ranged from 4 to 9 months after implantation depending on the trial. (By comparison, after implantation of bare metal stents percentage intimal hyperplasia volume averages 30%.) NO = nitric oxide; PC = phosphorylcholine.
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Figure 2 This patient underwent Cypher stent implantation in a right coronary stenosis; the final angiogram is shown in A. At follow-up (B) there was a focal angiographic aneurysm in the proximal right coronary (arrow). The final (post-implantation) IVUS is shown in C, and the follow-up IVUS is shown in D. Note the late stent malapposition most prominently indicated by the white asterisk. There has been an increase in external elastic membrane cross-sectional area (CSA) from 17.8 mm2 to 28.9 mm2 along with an increase in effective lumen CSA (intra-stent lumen CSA plus area of malapposition) from 8.8 mm2 to 16.8 mm2. The stent CSA (8.8 mm2) and the peri-stent plaque and media CSA (8.9 mm2) have not changed.
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Figure 3 This long right coronary artery stenosis (A, arrow) was treated with two overlapping Cypher stents (33 mm and 15 mm in length) with the final result in B. At 7-month follow-up there was focal in-stent restenosis (C, arrow). D (final post-implantation intravascular ultrasound [IVUS]) and E (follow-up IVUS) show identical image slices. At the site of focal intimal hyperplasia (E, white asterisk), the minimum lumen CSA (line of white dots) measured 2.0 mm2, and there was a paucity of stent struts (actually, only 1 stent strut) compared with the same image slice in D. Intimal hyperplasia was very focal and extended for <2 mm proximally and distally. This is an example of focal intra-Cypher stent restenosis, probably from strut fracture (struts were apparent at implantation that were not seen at follow-up).
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Figure 4 Pre-intervention, post-intervention, and follow-up angiograms, respectively, are shown at top; slices a b, and c in the post-intervention and follow-up angiograms correspond to the intravascular ultrasound examples at bottom. In slice b, corresponding to the center of the in-stent restenosis, there is heterogeneous stent strut distribution. Note that the three struts marked with the asterisk are farther apart than the others and that this is associated with more neointimal hyperplasia. (From Takebayashi et al. [35].)
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