Fig. 18.1
A case of early in-stent restenosis who received bare-metal stent. Angioscopy revealed complete coverage with white plaque
Fig. 18.2
Red thrombus (arrows) around stent struts
Fig. 18.3
A case of late in-stent restenosis who received drug-eluting stent. New formation of yellow plaque on stent was found by an angioscopy
However, these angioscopic findings (including the existence of angioscopic [subclinical] thrombi) had no direct link to major cardiac events including thrombotic clinical events and ISR. We have also shown that the lower minimum grade and more heterogeneous properties of neointimal coverage and thrombi in DES cases compared to BMS cases at 8 months’ angioscopic evaluation did not correlate with cardiac events (including ISR) over a period of 3 years [16]. Other studies demonstrated that yellow plaques (which can be visualized only by angioscopy) may be correlated with advanced atherosclerotic degeneration ruptures and may lead to neointimal progression including ISR in both BMS and DES cases [12, 17]. We thus believe that the angioscopic findings, especially those of yellow plaque, at an 8-month follow-up can be used as a marker to predict future cardiac events, including ISR.
18.3 Angioscopic Evaluation for Late ISR (≧1 Year)
Neoatherosclerosis is an important indicator of late ISR in both BMS and DES cases [18]. In DES cases, neoatherosclerosis occurred in >40 % of the patients by 9 months after implantation, whereas in BMS cases, it did not begin to appear until 2 years and remained a rare finding until 4 years [19]. Moreover, it was reported that DESs promoted the new formation of yellow neointima at 10 months after implantation [16] and that neoatherosclerosis occurred earlier in DES compared to BMS [18, 20, 21]. Thus, it is even more important to evaluate neoatherosclerosis in DES than in BMS.
Several OCT studies revealed that its findings of neoatherosclerosis involved the presence of neointimal disruption, lipid-laden neointima, lipid pools, thin-cap fibroatheromas (TCFAs) and macrophage accumulation [22, 23]. It was also shown that TCFA findings (Fig. 18.4) by OCT were well correlated with angioscopic yellow plaques, supported by a virtual histology-IVUS study [24] and a histological study [25]. Angioscopic evaluations may be useful to evaluate and predict late ISR correlated with neoatherosclerosis. If yellow plaque is detected in the late phase (≧1 year) after BMS or DES implantation, clinicians should pay close attention to the possibility of neoatherosclerosis, which may lead to late ISR.
Fig. 18.4
White arrows: thin-cap fibroatheromas (TCFA) in in-stent tissue detected by optical coherence tomography (OCT). Red arrows: the stent strut
18.4 Summary
Angioscopy is the only modality that directly visualizes the surface of the coronary artery lumen. In the early ISR phase, angioscopic findings of complete coverage by white neointima are well correlated with stable condition after stent implantation. However, if a patient shows ischemic findings due to narrowing of the coronary lumen, repeated intervention therapy should be performed. In the late ISR phase, angioscopic findings of yellow plaque may be correlated with neoatherosclerosis. When yellow plaque is angioscopically identified in this phase, careful follow-up should be conducted to examine the multifaceted and elusive condition causing both ISR and stent thrombosis.
References
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Cassese S, Byrne RA, Tada T, Pinieck S, Joner M, Ibrahim T, King LA, Fusaro M, Laugwitz KL, Kastrati A. Incidence and predictors of restenosis after coronary stenting in 10 004 patients with surveillance angiography. Heart. 2014;100:153–9.PubMedCrossRef
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