Clinical vignettes
Contribution of organized thrombus to in-stent restenosis after sirolimus-eluting stent implantation: optical coherence tomography findings
Kenichi Fujii*, Motomaru Masutani, and Mitsumasa Ohyanagi
Division of Coronary Heart Disease, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 6638501, Japan
* Corresponding author. Tel: +81 798 45 6553, Fax: +81 798 45 6551. Email: kfujii@hyo-med.ac.jp
A 58-year-old man with hypercholesterolaemia and diabetes mellitus was admitted for exertional angina pectoris. Coronary angiography showed a 90% stenosis in the mid-right coronary artery (Panel A) and optical coherence tomography (OCT: LightLabTM) was performed to assess plaque morphology. OCT revealed diffusely bordered signal poor region with overlying signal-rich band at the culprit site (L indicates lipid core in Panel B). Two sirolimus-eluting stents (CypherTM; 3.0 × 33 and 3.0 × 33 mm) were deployed in the culprit lesion and excellent angiographic results were obtained (Panel C). The final intravascular ultrasound also demonstrated the well-expanded and apposed stents with no plaque protrusion. The patient was prescribed aspirin 100 mg and ticlopidin 200 mg orally daily for 1 year. Twelve months follow-up coronary angiography showed a 99% stenosis with contrast filling defect in the stents (Panel D). At this site, OCT revealed a low-backscattering projections irregular mass protruding into the lumen (white arrows in Panel E) with some microchannels (white arrowheads in Panel F). This finding may suggest that organized thrombus was the main component of restenotic tissue 12 months after sirolimus-eluting stent implantation.
Stent fracture and suboptimal stent expansion are thought to be the mechanism of restenosis after sirolimus-eluting stent implantation. Our images suggest that intra-stent thrombus accumulation may represent a new potential mechanism of restenosis after sirolimus-eluting stent implantation. OCT, which is a new high-resolution (approximately 10 µm) imaging modality, may be a useful tool for assessing the mechanism of restenosis after drug-eluting deployment.
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