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Competing Interests: Funding Support and Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

This case report describes a patient who underwent implantation of a bare-metal stent (BMS) for the treatment of everolimus-eluting stent (EES) restenosis caused by chronic stent recoil, and the BMS successfully escaped from duplicate restenosis and target lesion revascularization (TLR).

A 58-year-old male with a history of prior myocardial infarction, hypertension, and dyslipidemia was admitted due to deteriorating exertional angina. A bare metal stent (Multilink plus™, GUIDANT Corporation, Santa Clara, CA, USA) had been implanted into the proximal left anterior descending artery because of ST-elevation myocardial infarction 7 years earlier. Optical coherence tomography (OCT) showed a disruption of the atherosclerotic neointima overlying the stent. Intravascular imaging studies and pathological studies have shown that neointima within a bare-metal stent often transform into atherosclerotic tissue during an extended period of time. In the current report, OCT demonstrated that a disruption of the atherosclerotic neointima has the potential to cause the development of unstable clinical features. OCT examinations therefore help to understand the pathogenesis of acute coronary syndrome after stent implantation.

Background: Although in-stent restenosis (ISR) after bare-metal stent (BMS) implantation is considered to be clinically benign, ISR is often associated with adverse complications, such as acute coronary syndrome (ACS). The frequency, type, and location of thrombi in ISR lesions and their clinical presentation have not yet been precisely validated., Methods: Thirty angiographic ISR lesions occurring within 3 to 8 months after stenting were evaluated by optical coherence tomography (OCT). A thrombus was defined as a mass protruding into the lumen with an irregular surface, and its type was divided into red or white. The maximum size of a thrombus and the longitudinal distance from the thrombus to the narrowest lumen were measured., Results: A thrombus was identified in 2 patients by angiography and in 10 patients by OCT (7% vs. 33%; P=0.01). OCT showed that 9 patients had white thrombus and another patient had both types of thrombi. ACS relevant to ISR was seen in 6 patients, and the frequency of ACS was significantly higher in patients with thrombus than in those without thrombus [50% (5/10) vs. 5% (1/20); P=0.003]. The maximum size of the thrombus was 412 ± 220 µm in height, 424 ± 251 µm in width, and the longitudinal distance between the thrombus and the minimum lumen area was 0.3 ± 0.7 mm., Conclusions: One third of ISR lesions following BMS deployment dominantly contained a white thrombus, and half of them were associated with ACS. A small thrombus formation adjacent to the narrowest lumen in an ISR lesion may therefore contribute to the clinical presentation of ACS., (Copyright © 2009 Elsevier B.V. All rights reserved.)

Background: Although very late stent thrombosis occurs several years after implantation of sirolimus-eluting stent (SES), the morphologic changes of the stent beyond 2 years have not yet been systematically studied in living patients. The late vascular response to SES was therefore evaluated by serial angioscopic studies at 2 and 5 years after stent implantation., Methods: A total of 17 patients with 17 SES underwent a repeated angioscopy procedure at 2 and 5 years. Neointimal stent coverage (NSC) was classified as follows: grade 0, presence of uncovered struts; grade 1, visible struts through a thin neointima; or grade 2, complete neointimal coverage without visible struts. For each patient, the minimum and maximum NSC grade and the existence of in-stent thrombus were recorded., Results: The minimum and maximum NSC grade did not increase between the 2 and 5 years (0.59 ± 0.51 vs 0.88 ± 0.70, P = .17, and 1.82 ± 0.39 vs 1.94 ± 0.24, P = .30, respectively). The prevalence of patients with uncovered struts did not significantly decrease from 2 to 5 years (41% vs 29%, P = .49). During the follow-up period, 3 of 6 thrombi disappeared, whereas new thrombus formation was found in 3 patients without any clinical symptoms. In-stent thrombus did not decrease (35% vs 35%, P > .99)., Conclusions: The current serial angioscopic study suggests that incomplete NSC and the prevalence of latent thrombus within the SES segments did not decrease from 2 to 5 years. The risk of stent thrombosis related to incomplete healing of SES may continue for an extended period., (Copyright © 2011 Mosby, Inc. All rights reserved.)

Aim: The elevation of troponin-T (TnT) and occurrence of transient slow-flow phenomena have been recognized as procedure-related myocardial injuries. Little is known about the characteristics of high-risk plaque resulting in myocardial injury after coronary stenting., Methods: The culprit plaques in 42 consecutive patients with stable angina undergoing elective coronary stenting were observed by angioscopy. The plaque color upon angioscopic examination was classified as either intense yellow or not yellow. Slow flow was defined as < TIMI grade 3 flow during the procedure. The TnT levels were measured 8, 16, and 24 hours after stenting, and myocardial injury was defined as TnT ≥ 0.03 ng/mL at any time point., Results: Twenty-four patients (57%) had intense yellow plaques and myocardial injury occurred in 22 patients (52%). The frequency of intense yellow plaque was significantly higher in the patients with myocardial injury than in those without myocardial injury (91% vs. 20%, p < 0.001). Transient slow flow occurred frequently in patients with myocardial injury than in those without myocardial injury (23% vs. 0%, p = 0.049). All patients with transient slow flow had intense yellow plaques at the culprit lesions., Conclusions: Intense yellow culprit plaque coloration was closely associated with TnT elevation and flow complications following elective coronary stenting. Angioscopically-observed intense yellow coloration may therefore predict high-risk plaque for peri-procedural myocardial injury.

Objectives: We examined the neointimal characteristics of bare-metal stents (BMS) in extended late phase by the use of optical coherence tomography (OCT)., Background: The long-term neointimal features after BMS implantation have not yet been fully characterized., Methods: Intracoronary OCT observation of BMS segments was performed during the early phase (<6 months, n = 20) and late phase (>or=5 years, n = 21) after implantation. Internal tissue of the BMS was categorized into normal neointima, characterized by a signal-rich band without signal attenuation, or lipid-leaden intima, with marked signal attenuation and a diffuse border. In addition, the presence of disrupted intima and thrombus was evaluated. Neovascularization was defined as small vesicular or tubular structures, and the location of the microvessels was classified into peristent or intraintima., Results: Normal neointima proliferated homogeneously, and lipid-laden intima was not observed in the early phase. In the late phase, lipid-laden intima, intimal disruption, and thrombus frequently were found in comparison with the early phase (67% vs. 0%, 38% vs. 0%, and 52% vs. 5%, respectively; p < 0.05). Persistent neovascularization demonstrated a similar incidence between the 2 phases. The appearance of intraintima neovascularization was more prevalent in the late phase than the early phase (62% vs. 0%, respectively; p < 0.01) and in segments with lipid-laden intima than in nonlipidic segments (79% vs. 29%, respectively; p = 0.026)., Conclusions: This OCT study suggests that neointima within the BMS often transforms into lipid-laden tissue during an extended period of time and that expansion of neovascularization from peristent to intraintima contributes to atherosclerotic progression of neointima., (Copyright (c) 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Although coronary angiograms after bare-metal stent (BMS) implantation show late luminal narrowing beyond 4 years, the detailed changes inside the BMS have not yet been fully elucidated., Methods and Results: Serial angiographic and angioscopic examinations were performed immediately (baseline), 6 to 12 months (first follow-up), and >or=4 years (second follow-up) after stenting without target lesion revascularization in 26 segments of 26 patients who received BMS deployment for their native coronary arteries. Angioscopic observation showed atherosclerotic yellow plaque crushed out by stent struts in 22 patients (85%) and mural thrombus in 21 patients (81%) at baseline. At first follow-up, white neointimal hyperplasia was almost completely buried inside the struts, and both yellow plaque and thrombus had decreased in comparison with baseline (12% and 4%, respectively; P<0.001). The frequencies of yellow plaque and thrombus increased from the first to second follow-ups (58% and 31%, respectively; P<0.05). All of the yellow plaques in the second follow-up were located not exterior to the struts but protruding from the vessel wall into the lumen. Late luminal narrowing, defined as an increasing of percent diameter stenosis between the first and second follow-ups, was greater in segments with yellow plaque than in those without yellow plaque (18.4+/-17.3% versus 3.6+/-4.2%, respectively; P=0.011)., Conclusions: This angiographic and angioscopic study suggests that white neointima of the BMS may often change into yellow plaque over an extended period of time, and atherosclerotic progression inside the BMS may contribute to late luminal narrowing.

A polytetrafluoroethylene (PTFE)-covered stent is specially used to treat coronary perforation complicating percutaneous intervention in order to prevent the aneurysm from rupturing, but until now it has not been known if endothelialization occurs inside this type of stent. A patient with a giant aneurysm of the right coronary artery underwent successful implantation of a PTFE-covered stent. Angiography at 9-month follow-up showed focal restenosis at the proximal edge of the stent and coronary angioscopy revealed restenosis as a result of thrombus formation. Absence of endothelialization in the covered stent was also detected by angioscopy and optical coherence tomography. These findings suggest that in-stent thrombosis must be prevented after PTFE-covered stent implantation.

No detailed data regarding neointimal coverage of bare-metal stents (BMSs) at 3 months after implantation was reported to date. This investigation was designed to evaluate the neointimal coverage of BMSs compared with sirolimus-eluting stents (SESs) using optical coherence tomography. A prospective optical coherence tomographic follow-up examination was performed 3 months after stent implantation for patients who underwent BMS (n = 16) or SES implantation (n = 24). Neointimal hyperplasia (NIH) thickness on each stent strut and percentage of NIH area in each cross section were measured. Malapposition of stent struts to the vessel wall and the existence of in-stent thrombi were also evaluated. There were 5,076 struts of SESs and 2,875 struts of BMSs identified. NIH thickness and percentage of NIH area in the BMS group were higher than in the SES group (351 +/- 248 vs 31 +/- 39 mum; p <0.0001; 45.0 +/- 14% vs 10.0 +/- 4%; p <0.0001, respectively). The frequency of uncovered struts was higher in the SES group than the BMS group (15% vs 0.1%; p <0.0001). Malapposed struts were observed more frequently in the SES group than the BMS group (15% vs 1.1%; p <0.0001). In conclusion, there was no difference in incidence of in-stent thrombus between the 2 groups (14% vs 0%; p = 0.23). The present study showed almost all BMS struts to be well covered at a 3-month follow-up, suggesting that patients receiving BMS stents may not require dual-antiplatelet therapy >3 months after implantation.

In-stent restenosis is the Achilles' heel of standard or bare-metal stent (BMS) implantation, occurring in 10-40% of the patients. Drug-eluting stent (DES) are supposed to inhibit inflammation and neointimal growth and, subsequently, in-stent restenosis. The neointimal proliferation inside the stent is recognized as lumen late loss on angiograms or as an obstruction area (or volume) on intravascular ultrasound (IVUS) in chronic phase. Coronary angioscopy provides direct visualization of the lumen and is capable of macroscopic pathologic diagnosis of atherosclerotic plaques and intracoronary thrombi. This modality is also able to supply detailed information on stent coverage with neointimal hyperplasia. The neointimal growth inside the stent is evaluated as white neointimal coverage over the stent struts. Angioscopic view inside the DES is quite different from that inside the BMS. In this article, the difference in angioscopic findings between the DES and the BMS is shown.

Confirming complete neointimal coverage after implantation of a drug-eluting stent is clinically important because incomplete stent coverage is responsible for late thrombosis and sudden cardiac death. Optical coherence tomography is a high-resolution (approximately 10 microm) imaging technique capable of detecting a thin layer of neointimal hyperplasia (NIH) inside a sirolimus-eluting stent (SES) and stent malapposition. This investigation evaluated stent exposure and malapposition 3 months after SES implantation using optical coherence tomography in a different clinical presentations, such as acute coronary syndrome (ACS) and non-ACS. Motorized optical coherence tomographic pullback (1 mm/s) was performed at 3-month follow-up to examine consecutive implanted 31 SESs in 21 lesions in 21 patients (9 with ACS and 12 with non-ACS). NIH thickness inside each strut and percent NIH area in each cross section were measured. In total, 4,516 struts in 567-mm single-stented segments were analyzed. Overall, NIH thickness and percent NIH area were 29 +/- 41 microm and 10 +/- 4%, respectively. Rates of exposed struts and exposed struts with malapposition were 15% and 6%, respectively. These were more frequent in patients with ACS than in those with non-ACS (18% vs 13%, p <0.0001; 8% vs 5%, p <0.005, respectively). In conclusion, neointimal coverage over a SES at 3-month follow-up is incomplete in ACS and non-ACS. Our study suggests that dual antiplatelet therapy might be continued >3 months after SES implantation.

Aims: The neointimal coverage and intracoronary thrombi within stented segments at 6 months after implantation between sirolimus-eluting stents (SESs) and bare metal stents (BMSs) were compared by direct visualization using angioscopy., Methods and Results: Forty-six patients (36 stable angina and 10 acute coronary syndrome) were treated with 33 SESs and 33 BMSs. Immediately after and 6 months after stenting, each of the stented segments, edge body, and overlapping segment were observed by angioscopy and the grade of neointimal coverage over the stents was classified as 0: absent neointima, 1: visible struts through thin neointima, or 2: invisible struts. The existence of thrombi was also evaluated. The average grade of the neointimal coverage at 6 months follow-up was lower in the SES than that in the BMS (edge: 1.4+/-0.7 vs. 1.9+/-0.2, body: 1.0+/-0.5 vs. 1.8+/-0.5, overlapping segment: 0.6+/-0.7 vs. 1.8+/-0.5; P<0.0001, P<0.0001, P=0.0069, respectively). The frequency of persistence of thrombus was significantly higher in the SESs than that in the BMSs (86 vs. 29%, respectively; P=0.031)., Conclusion: The present study suggested a delayed neointimal stent coverage and slower thrombus disappearance process in the SESs in comparison to the BMSs.

Objectives: The aim of this study was to investigate the morphologic changes in infarct-related lesions after stenting in acute or recent myocardial infarction (MI) with coronary angioscopy., Background: There is no information on the serial morphologic changes, which occur after stenting, and the time course of neointimal coverage of stents for disrupted unstable plaques., Methods: Forty-three patients with MI within seven days of onset were examined. Angioscopy was serially performed for the infarct-related lesions at baseline (n = 43), after balloon angioplasty (n = 35), and after stenting following balloon angioplasty (n = 39) and at one (n = 36) and six months (n = 30) after stenting., Results: At baseline, most of the lesions had complex morphology, yellow plaque color, and protruding thrombus (96%, 96%, and 74%, respectively). Although balloon angioplasty reduced the protruding thrombus, it remained in 37%, and an intimal flap was observed in 89% of the lesions. After stenting, the protruding thrombus and intimal flap disappeared, with an increased luminal size obtained in all lesions. At one-month follow-up, an irregular and yellow surface, along with a lining thrombus, was still observed, with partial neointimal stent coverage in most of the lesions. At six-month follow-up, the neointima was found to have sufficiently formed over the stent. The plaque shape and color were almost all classified as smooth (97%) and white (93%)., Conclusions: These results suggest that a stent not only compressed and covered a disrupted plaque with a protruding thrombus and intimal flap, leading to a wide vessel lumen, but also helped to seal the unstable plaque through neointimal proliferation.

The article presents a study which investigated the relationship between angiographic late loss and the presence of thrombus based on angioscopic findings within paclitaxel-eluting stents (PES) and sirolimus-eluting stents (SES). Quantitative coronary angiography was used to measure late loss. Results showed that the prevalence of patients with uncovered struts did not differ and in-stent thrombus was found more frequently in PES than in SES.