Heterogeneous Arterial Healing in Patients Following Paclitaxel-Eluting Stent Implantation

Coronary arterial repair in patients with stable angina pectoris or acute coronary syndrome after ultrathin biodegradable polymer sirolimus-eluting stent implantation at 1-year follow-up by coronary angioscopy

BACKGROUND

Imaging modality-based evidence is limited that compares the extent of coronary arterial repair after percutaneous coronary intervention between patients with stable angina pectoris (SAP) and those with acute coronary syndrome (ACS).

METHODS

Between December 2018 and November 2021, a single-center, nonrandomized, observational study was conducted in 92 patients with SAP (n = 42) or ACS (n = 50), who were implanted with Orsiro sirolimus-eluting stent (O-SES) providing a hybrid (active and passive) coating and underwent 1-year follow-up by coronary angioscopy (CAS) after implantation. CAS assessed neointimal coverage (NIC), maximum yellow plaque (YP), and mural thrombus (MT).

RESULTS

Baseline clinical characteristics were comparable between the SAP and ACS groups. The follow-up periods were comparable between the two groups (390.1 ± 69.9 vs. 390.6 ± 65.7 days, p = 0.99). The incidences of MT at 1 year after implantation were comparable between the two groups (11.4% vs. 11.1%, p = 0.92). The proportions of "Grade 1" in dominant NIC grades were highest in both groups, and the proportions of maximum YP grades and MT were comparable between the two groups.

CONCLUSION

O-SES-induced coronary arterial repair at the site of stent implantation, irrespective of the types of coronary artery disease.

Early- and Middle-Phase Angioscopic Assessment of Arterial Healing Following Current Drug-Eluting Stent Implantation in Patients With Acute Coronary Syndrome

Background: Drug-eluting stents (DESs) have been widely used for the treatment of acute coronary syndrome (ACS). However, there are few reports on early- and middle-phase arterial repair after DES implantation in ACS patients. Methods and Results: Coronary angioscopy (CAS) findings covering the early and middle phases (mean [±SD] 4±1 and 10±2 months, respectively) of arterial healing after second- and later-generation DES placement between May 2009 and January 2020 were extracted from the Kansai Rosai Hospital Cardiovascular Center database. Neointimal coverage (NIC), yellow color intensity, and the incidence of thrombus adhesion were compared between ACS and chronic coronary syndrome (CCS) in the early (54 stents of 47 lesions, 38 ACS patients; 86 stents of 70 lesions, 52 CCS patients) and middle (179 stents of 154 lesions from 136 ACS patients; 459 stents of 374 lesions from 287 CCS patients) phases. In the early phase, NIC, the incidence of thrombus adhesion (ACS, 39.1%; CCS, 38.0%), and maximum yellow color grade were similar between the 2 groups. In the middle phase, although the maximum yellow color grade was significantly higher in the ACS group (P=0.013), NIC and the incidence of thrombus adhesion (ACS, 24.6%; CCS, 23.4%) were similar in the 2 groups. Conclusions: Arterial healing assessment with CAS showed that NIC and the incidence of thrombus adhesion after DES implantation were similar between ACS and CCS patients.

Mobilization of progenitor cells and vessel healing after implantation of SYNERGY in acute coronary syndrome

This study was aimed to compare the vascular healing process of a SYNERGY stent with that of a PROMUS PREMIER stent in patients with acute coronary syndrome (ACS). In 71 patients with ACS, undergoing coronary stent implantation using the SYNERGY stent (n = 52) or PROMUS PREMIER stent (n = 19), we measured circulating CD34+/CD133+/CD45^null cells and CD34+/KDR+ cells and observed vascular healing at the stented sites using optical coherence tomography (OCT) and coronary angioscopy. On the day 7, circulating CD34+/CD133+/CD45^null cells increased in SYNERGY group (P < 0.0001), while it did not change in PROMUS group. The CD34+/KDR+ cells also increased in SYNERGY group (P < 0.0001) but less significantly in the PROMUS group (P < 0.05). The OCT-based neointimal thickness (P < 0.0005) and neointimal coverage rate (P < 0.05) at 12 months were greater in SYNERGY group, compared with PROMUS group. The coronary angioscopy-based neointimal coverage grade at 12 months was also greater in SYNERGY group (P < 0.001). In overall patients, the change in CD34+/KDR+ cells on the day 7 correlated with the OCT-based neointimal thickness at 12 months (R = 0.288, P < 0.05). SYNERGY stent seems to have potential advantages over PROMUS PREMIER stent for ACS patients in terms of vascular healing process at the stented sites.

Arterial Healing 10 Months After Implantation of an Ultrathin-Strut, Biodegradable-Polymer, Sirolimus-Eluting Stent - An Angioscopic Study

Background: The OrsiroTM ultrathin-strut, biodegradable-polymer, sirolimus-eluting stent (O-SES) has specific characteristics regarding its components and has demonstrated comparable clinical outcomes compared with durable-polymer, drug-eluting stents (DES). However, arterial repair following deployment of the O-SES has not been elucidated to date. Methods and Results: Using data from the Kansai Rosai Hospital database between November 2010 and September 2020, we analyzed coronary angioscopy (CAS) findings a mean (±SD) of 10±2 months after implantation of an O-SES, a durable-polymer everolimus-eluting stent (XienceTM; X-EES), or a biodegradable-polymer everolimus-eluting stent (SynergyTM; S-EES). Neointimal coverage (NIC), yellow color intensity of the stented segment, and the incidence of thrombus adhesion were compared between the O-SES (66 stents from 42 patients), X-EES (119 stents from 87 patients), and S-EES (132 stents from 88 patients). NIC was significantly thinner for the O-SES than S-EES (P<0.001), but was similar between the O-SES and X-EES (P=0.25). Yellow color intensity was significantly greater for the O-SES than X-EES (P<0.001), but similar between the O-SES and S-EES (P=0.51). The incidence of thrombus adhesions was similar in all 3 groups. Conclusions: O-SES and X-EES resulted in similar inhibition of NIC and both resulted in a thinner NIC than with S-EES. In addition, O-SES exhibited a similar degree of thrombus adhesion as the other DES, suggesting similar thrombogenicity.

Consensus document on the standard of coronary angioscopy examination and assessment from the Japanese Association of Cardiovascular Intervention and Therapeutics

Coronary angioscopy (CAS) is a unique diagnostic device that allows direct visualization of the vascular luminal surface in living patients. CAS contributes to elucidate the pathology of coronary artery disease. This consensus document provides a standard for CAS examination and assessment.

Angioscopic assessments and clinical outcomes one year after polymer-free biolimus A9-coated coronary stent implantation

BACKGROUND

Polymer-free biolimus A9-coated coronary stent (DCS) has novel features which lead to the expectation of better arterial healing. However, comparisons of intravascular status between DCS and drug-eluting stents (DES), and robust real-word clinical assessments of DCS have been lacking to date.

METHODS

From September 2017 to September 2018, we evaluated the intra-vascular status of 74 DCS implanted in 55 lesions from 43 patients using coronary angioscopy (CAS) approximately one year after implantation from a cohort of 219 lesions in 158 patients. We set 239 second-generation durable-polymer DES (DP-DES) implanted in 211 lesions from 180 patients from a cohort of 2652 lesions in 1914 patients as the control. Angioscopic images were analyzed to determine (1) the dominant degree of neointimal coverage (NIC) over the stent; (2) the heterogeneity of NIC; (3) yellow color grade of the stented segment; and (4) the presence of intra-stent thrombus. The primary outcome was the incidence of thrombus and secondary outcomes were the other CAS findings, and the 1-year clinical outcomes which included target lesion revascularization (TLR) and major adverse cardiac events (MACE). To minimize inter-group differences in baseline characteristics, propensity score matching was performed for clinical outcomes.

RESULTS

Incidence of thrombus adhesion was similar in DCS and DP-DES groups (28.4% versus 22.6%, p=0.31). However, the dominant NIC grade was significantly higher in DCS (p<0.001), while NIC was more heterogeneous in DCS than in DP-DES (p=0.001). Maximum yellow color grade was similar (p=0.22). After propensity score matching, 202 lesion pairs from 146 patient pairs were retained for analysis. The cumulative incidence of TLR (4.6% versus 3.8%, p=0.38) and MACE (11.6% versus 11.7%, p=0.84) was similar for DCS and DP-DES.

CONCLUSIONS

DCS showed thrombus adhesion and clinical outcomes at 1 year similar to DP-DES. DCS can thus be used with similar safety and efficacy as DP-DES.

Different vascular healing process between bioabsorbable polymer-coated everolimus-eluting stents versus bioresorbable vascular scaffolds via optical coherence tomography and coronary angioscopy (the ENHANCE study: ENdothelial Healing Assessment with Novel Coronary tEchnology)

Recent clinical trials have raised concerns about the safety and efficacy of ABSORB™ bioresorbable vascular scaffolds (BVS). The difference in the vascular healing process between SYNERGY™ bioabsorbable polymer-coated everolimus-eluting stents (BP-EES) and BVS remains unclear. The aim of the ENHANCE study was to compare vascular healing on BP-EES versus BVS by optical coherence tomography (OCT) and coronary angioscopy (CAS) at 4- and 12-month follow-ups. This is a prospective, non-randomized, single center clinical trial. Thirteen eligible patients with multivessel disease were enrolled. BP-EES and BVS were simultaneously implanted in the same patients, but in different coronary vessels. Imaging follow-up with both OCT and CAS was completed in 11 patients at 12 months. Neointimal coverage rates were similar between the two groups based on OCT measurements. The neointimal thickness of BP-EES was significantly thicker at the 12th month than at the 4th month, whereas the neointimal thickness of BVS did not change between the measurements taken at the 4th and 12th month. Existence of intra-stent thrombus was significantly higher in the BVS group, compared to the BP-EES group. On the other hand, CAS revealed that red-thrombi and yellow-plaque were more frequently observed in BVS at 4 months and up to 12-month follow-ups than in BP-EES. These findings suggested that the evidence of instability remained up to 12 months in the vascular healing with BVS, compared to that with BP-EES. Vascular healing of the stented wall was recognized at the very early phase after BP-EES implantation. However, vascular healing with BVS was still incomplete after 12 months.

Refractory Vascular Wall Healing after Paclitaxel-Coated Nitinol Stent Implantation in the Femoropopliteal Artery: A High-Resolution Angioscopic Assessment

It is unclear whether arterial healing occurs beyond 1 year following paclitaxel-coated stent implantation in peripheral artery disease. An 81-year-old woman with superficial femoral artery disease underwent endovascular therapy with a paclitaxel-coated stent. An angiography 21 months later revealed peri-stent contrast staining in the superficial femoral artery, and optical frequency domain imaging demonstrated incomplete stent apposition with significant positive vascular remodeling. High-resolution angioscopy detected positive vascular wall remodeling and in-stent yellow plaque more clearly than conventional angioscopy. Refractory superficial femoral arterial wall healing was apparent more than 20 months after paclitaxel-coated stent implantation.

Association of Subclinical Intrastent Thrombus Detected 9 Months After Implantation of 2nd-Generation Drug-Eluting Stent With Future Major Adverse Cardiac Events - A Coronary Angioscopic Study

BACKGROUND

Detection of yellow plaques (YP) by coronary angioscopy (CAS) 1 year after 1st-generation drug-eluting stent (DES) implantation has been related to future coronary events. However, the association between CAS findings and clinical outcomes following 2nd-generation DES implantation has not been investigated.

METHODS AND RESULTS

This study included a total of 248 2nd-generation DES in 179 patients, who were examined by CAS 9±2 months after implantation. Angioscopic evaluation included dominant neointimal coverage (NIC) grade, heterogeneity of NIC, presences of YP and intrastent thrombus. The outcome measure was major adverse cardiac events (MACE) defined as a composite of cardiac death, acute myocardial infarction and any coronary revascularization. The association between the CAS findings and MACE was evaluated using the Kaplan-Meier method. A Cox proportional hazards model was used to assess the predictors of MACE. The mean follow-up duration was 1,367±843 days. Dominant NIC grade (P=0.98), heterogeneity of NIC (P=0.20) and YP (P=0.53) were not associated with the incidence of MACE. However, intrastent thrombus was significantly associated with MACE (P=0.033). Intrastent thrombus (adjusted hazard ratio: 2.22; 95% confidence interval [CI]: 1.12-4.39), acute coronary syndrome (2.83; 95% CI: 1.42-5.67) and B2/C lesion (2.13; CI: 1.12-4.05) were independent predictors of MACE.

CONCLUSIONS

Subclinical intrastent thrombus observed by CAS at 9 months after 2nd-generation DES implantation was independently associated with poor clinical outcome.

Satisfactory arterial repair 1 year after ultrathin strut biodegradable polymer sirolimus-eluting stent implantation: an angioscopic observation

The ultrathin strut biodegradable polymer sirolimus-eluting stent (Orsiro, O-SES) exhibits satisfactory clinical outcomes. However, no report to date has documented the intravascular status of artery repair after O-SES implantation. We examined 5 O-SES placed in 4 patients (age 65 ± 12 years, male 75%) presenting with stable angina pectoris due to de novo lesions in native coronary arteries. Coronary angioscopy was performed immediately after percutaneous coronary intervention and 1 year later. Angioscopic images were analyzed to determine the following: (1) dominant grade of neointimal coverage (NIC) over the stent; (2) maximum yellow plaque grade; and (3) existence of thrombus. Yellow plaque grade was evaluated both immediately after stent implantation and at the time of follow-up observation. The other parameters were evaluated at the time of follow-up examination. NIC was graded as: grade 0, stent struts exposed; grade 1, struts bulging into the lumen, although covered; grade 2, struts embedded in the neointima, but translucent; grade 3, struts fully embedded and invisible. Yellow plaque severity was graded as: grade 0, white; grade 1, light yellow; grade 2, yellow; and grade 3, intensive yellow. Angioscopic findings at 1 year demonstrated the following: dominant NIC grade 1, grade 2, and grade 3 in 1, 2, and 2 stents, respectively; all stents were covered to some extent; focal thrombus adhesion was observed in only 1 stent. Yellow plaque grade did not change from immediately after stent implantation to follow-up. O-SES demonstrated satisfactory arterial repair 1 year after implantation.

Impact of analysis interval size on the quality of optical frequency domain imaging assessments of stent implantation for lesions of the superficial femoral artery

OBJECTIVES

This study aimed to investigate the influence of analysis interval size on optical frequency domain imaging (OFDI) assessment of stent therapy for lesions of the superficial femoral artery (SFA).

BACKGROUND

No consensus or validating data are available with respect to the methodology of intravascular imaging analysis for the peripheral arteries.

METHODS

OFDI was performed for 30 SFA lesions, during endovascular therapy and at the 6-month follow-up. Initially, lumen and stent borders were traced at 1-mm axial intervals. Volumes were calculated using a PC-based software, and the volume index (VI) was defined as the volume divided by the stent length. Two additional OFDI analyses were performed using 2-mm and 5-mm intervals, thereby reducing the number of cross-sectional image frames analyzed.

RESULTS

The mean stent length was 89.7 ± 35.2 mm. The mean difference in baseline minimum lumen area (MLA) was 0.4 mm² between MLA values from the 1-mm and 2-mm interval analyses, and 2.2 mm² between MLA values from the 1-mm and 5-mm interval analyses. In volumetric analysis, there were excellent correlations and good agreements for stent, lumen, and neointimal VI measurements obtained on the basis of different analysis intervals.

CONCLUSIONS

Using large intervals in OFDI analyses of SFA lesions resulted in few differences in measurement variability of volumetric parameters. However, planar analysis for MLA assessment can be susceptible to high variability when large intervals are applied. © 2016 Wiley Periodicals, Inc.

Comparison of the performance of zotarolimus- and everolimus-eluting stents by optical coherence tomography and coronary angioscopy

Overall stent performance should be characterized by geometric luminal gain acquisition, neointimal coverage of the stent struts, and stabilization of the underlying inflammatory neoatheroma. The aim of this study was to compare the performance of zotarolimus-eluting stent (ZES), everolimus-eluting stent (EES) and bare metal stent (BMS) using optical coherence tomography (OCT) and coronary angioscopy. For 36 stented coronary lesions (BMS, 12 lesions; ZES, 11 lesions; EES, 13 lesions) in 27 patients, we calculated neointimal area and uncovered stent strut rate based on OCT findings at 10 months after stent placement. The grades of neointimal coverage and yellow color, both of which were classified from 0 to 3, were also assessed by coronary angioscopy. The plaque area of the ZES lesions was larger than that of the EES lesions (P < 0.05) but smaller than that of the BMS lesions (P < 0.05). The OCT-based uncovered rate of the ZES lesions was less than that of the EES lesions (P < 0.01), but similar to that of the BMS lesions. The stent coverage grade by angioscopy was higher in the ZES lesions than in the EES lesions (P < 0.05), but similar to the BMS lesions. The yellow grade was less in the ZES lesions than in the EES lesions (P < 0.01), but similar to the BMS lesions. ZES might be better than BMS in terms of neointimal thickening, and better than EES in terms of neointimal coverage as well as prevention of neoatheroma formation. ZES may have superior performance compared with EES.

Pathological findings of late stent thrombosis after paclitaxel-eluting stent implantation for superficial femoral artery disease

A 76-year-old man presented with right critical limb ischemia. An angiography revealed right SFA occlusion. Therefore, two paclitaxel-eluting stents (Zilver PTXs 6.0 mm × 120 mm stents; Cook Medical, Bloomington, Indiana) were placed, which promoted good blood flow. Follow-up angiography at 6 months also showed no restenosis. However, 10 months later, the patient suddenly visited with acute-onset pain in the right leg. Computed tomography showed the acute occlusion at the stented SFA. Eventually, above-knee amputation was performed due to the poor general condition and progressive limb ischemia. As the pathological finding, heterogeneous neointima formation at the stented site was mainly found. Although neointimal layer consisting of smooth muscle cell (SMC) was partly observed, necrotic tissue was evident in the remaining portion. At the necrotic tissue site, the majority of the components of the material covered by the stent strut were fibrin deposits. The findings of regenerative endothelial cells were not observed at the luminal surface. Nuclei of medial SMCs were also lost between the arterial media and the stent strut. Late stent thrombosis after paclitaxel-eluting stenting for SFA lesion has not been sufficiently evaluated. Here, we report a case of late stent thrombosis with a review including pathological findings. <Learning objective: We reported that a 76-year-old man received paclitaxel-eluting stent for femoropopliteal disease. Ten months later, stent thrombosis was occurred and above-knee amputation was performed. As the pathological finding, heterogeneous neointima formation was mainly found and the regenerative endothelial cells were not observed. Our report suggested that delayed healing and uncovered strut caused by paclitaxel-exposure resulted in late stent thrombosis.>.

Angioscopic assessment of peri-stent contrast staining following drug-eluting stent implantation

BACKGROUND

Peri-stent contrast staining (PSS) has been recognized as a predictor of late stent thrombosis following drug-eluting stent (DES) implantation. However, the intravascular conditions at PSS sites remain unclear.

METHODS AND RESULTS

We evaluated 10 patients (median age 72 years, 80% male) with stable angina pectoris by coronary angioscopy. The patients had a total of 11 DES implantations (5 sirolimus-eluting stents; 4 paclitaxel-eluting stents; 2 everolimus-eluting stents) that showed PSS. Neointimal coverage (NIC), presence of thrombus, and yellow plaques underneath the stent were compared between PSS and non-PSS sites for each stent. NIC was graded as: grade 0, struts exposed; grade 1, struts bulging into the lumen, although covered; grade 2, struts embedded by neointima, but translucent; grade 3, struts fully embedded and invisible. Mean follow-up was 394±206 days (median: 289). NIC grade was lower at PSS sites (P=0.021) with 8 out of 11 stents (73%) having grade 0. Angioscopy detected a thrombus more frequently at PSS sites than at non-PSS sites (64% vs. 9%, P=0.012). Yellow plaques tended to be more significant at PSS sites than at non-PSS sites (82% vs. 45%, P=0.091).

CONCLUSIONS

The angioscopic findings suggest high thrombogenicity at PSS sites.

A higher colour grade yellow plaque was detected at one year after implantation of an everolimus-eluting stent than after a zotarolimus-eluting stent

OBJECTIVE

Neoatherosclerosis or atherosclerosis progression is one of the mechanisms of long-term stent failure. Yellow plaque detected by angioscopy has been associated with advanced atherosclerosis and the future risk of a coronary event. We compared the yellow colour of the stented segment between zotarolimus-eluting stents (ZES) and everolimus-eluting stents (EES) at 1 year after implantation.

DESIGN

Cross-sectional study.

PATIENTS

Consecutive patients underwent angioscopic examination 1 year after the implantation of ZES (n=45) or EES (n=45) at a de novo native coronary lesion.

MAIN OUTCOME MEASURES

The maximum yellow colour grade (grade 0-3) of the stented segment, maximum and minimum neointima coverage grade (grade 0-2) and the presence of thrombus were examined. The neointima heterogeneity index was calculated as maximum - minimum coverage grade.

RESULTS

Maximum yellow colour grade was higher in EES than in ZES (1.3±0.9 vs 0.4±0.8, p<0.001) and maximum (2.0±0.2 vs 1.2±0.5, p<0.001) and minimum (1.5±0.6 vs 0.7±0.5, p<0.001) coverage grade was higher in ZES than in EES. The neointima heterogeneity index was not different between ZES and EES (0.4±0.5 vs 0.5±0.6, p=0.42). The incidence of thrombus was very low and was not different between ZES and EES (2% vs 4%, p=0.55).

CONCLUSIONS

Although both ZES and EES had good healing with homogeneous neointima coverage and a low incidence of thrombus, EES had more advanced atherosclerosis as shown by the presence of higher grade yellow plaque than ZES at 1 year after implantation.

Comparisons of detailed arterial healing response at seven months following implantation of an everolimus- or sirolimus-eluting stent in patients with ST-segment elevation myocardial infarction

BACKGROUND

The difference of arterial healing response following everolimus-eluting stent (EES) or sirolimus-eluting stent (SES) implantation in patients with ST-segment elevated myocardial infarction (STEMI) has not been compared in detail.

METHODS

Thirty-five patients with STEMI were randomly implanted with an EES or SES (23 EES, 12 SES). At seven months, neointimal thickness (NIT) and strut malapposition were evaluated by optical coherence tomography (OCT) and the grade and heterogeneity of neointimal coverage (NIC) and development of intra-stent thrombi were evaluated by angioscopy.

RESULTS

No significant differences were noted in clinical events experienced by the two groups, although one patient with an EES died following a papillary muscle rupture and one patient with a SES experienced sub-acute stent thrombosis. On OCT, although the EES implants showed a greater NIT than the SES implants (94.8 ± 88.8 μm vs 65.6 ± 63.3 μm, P<0.0001), both the EES and SES showed an excellent suppression of neointimal proliferation in the culprit lesion of STEMI. The frequency of uncovered and malapposed struts of EES was significantly lower than that of SES (2.7% vs. 15.7%, P<0.0001, 0.7% vs. 2.3%, P<0.0001, respectively). The ratio of stents fully covered with neointima of EES group was significantly higher than that of SES group (P=0.04). Angioscopic analysis also showed greater dominant NIC grade with homogenous NIC in EES than in SES (P=0.03, P=0.0002, respectively). The incidence of massive intra-stent thrombus of EES was lower than that of SES (P=0.05).

CONCLUSION

For patients with STEMI, EES may promote better arterial healing response than SES.

Intravascular Ultrasound Results From the NEVO ResElution-I Trial

Background—

The NEVO sirolimus-eluting stent (NEVO SES) is a novel cobalt-chromium stent combining sirolimus release from reservoirs with bioabsorbable polymer to reduce spatial and temporal polymer exposure. The aim of this study was to assess the arterial response to the NEVO SES in a randomized, blinded comparison versus the surface-coated TAXUS Liberte paclitaxel-eluting stent (TAXUS Liberté PES) in human native coronary lesions using intravascular ultrasound (IVUS).

Methods and Results—

The NEVO ResElution-I IVUS substudy enrolled 100 patients (1:1 randomization). In addition to standard IVUS variables, uniformity of neointimal distribution within stents was evaluated in 3 dimensions by computing mean neointimal thickness within 12 equally spaced radial sectors on every 1-mm cross section along the stented segment. The NEVO SES showed significantly less neointimal proliferation (neointimal obstruction: 5.5±11.0% versus 11.5±9.7%, P =0.02), resulting in less late lumen area loss and smaller maximum cross-sectional narrowing at 6 months. The absolute variability of neointima distribution, assessed by the standard deviation of neointimal thickness within each stent, was significantly reduced with the NEVO SES compared with the TAXUS Liberté PES(0.04±0.04 mm versus 0.10±0.07 mm, P <0.0001). TAXUS Liberté PES showed significantly greater positive vessel remodeling than the NEVO SES (Δvessel volume index: 1.30±1.36 mm 3 /mm versus 0.36±0.63 mm 3 /mm, respectively, P =0.003).

Conclusions—

The NEVO SES with focal release of sirolimus from reservoirs achieved significantly greater and more consistent suppression of neointimal hyperplasia than the surface-coated TAXUS Liberté PES. This was associated with less positive remodeling and no increased morphological or morphometric abnormalities surrounding the stent or at the stent margins.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00714883.

Coronary angioscopy: current topics and future direction

Disruption of vulnerable plaque and following thrombus formation are considered the main cause of acute coronary syndrome (ACS). Intracoronary angioscopy is an endoscopic technology that allows direct visualization of the coronary artery lumen and provides detailed information regarding plaque morphology in patients with coronary artery disease. The color and morphology of coronary plaque under angioscopy observation are proposed to be determinants for plaque stability. Angioscopically yellow plaque represents a thin-cap fibroatheroma, and is associated with a higher incidence of disruption and thrombus formation, and may be associated with future acute coronary syndromes. To circumvent the subjectivity of color interpretation, various quantitative methods have been proposed for identifying vulnerable plaques. Superior to other coronary imaging techniques such as VH IVUS and optical coherence tomography, angioscopy has impressively high sensitivity and specificity in detection of intraluminal thrombus. Angioscopy can also be used as an adjunctive technique during catheter intervention by directly visualizing the thrombus, stent struts and proliferating neointima. The time course and pattern of neointima coverage, as seen by angioscopy, various among different stent systems. Angioscopic assessment of serial changes after stent implantation may have potential benefits on patient's management after coronary stenting.

Possible role of damaged neoendothelial cells in the genesis of coronary stent thrombus in chronic phase. A dye staining angioscopic study

The mechanism(s) underlying formation of coronary stent thrombus (ST) in chronic phase is yet unclear. Endothelial cells are highly antithrombotic, therefore, it is conceivable that neoendothelial cells (NECs) covering stent struts are damaged and cause ST. This study was performed to examine the role of damaged NECs covering coronary stent struts in the genesis of occlusive or nonocclusive ST in chronic phase.(1) Forty-four patients with acute coronary syndrome (17 females and 27 males) underwent dye-staining coronary angioscopy, using Evans blue which selectively stains damaged endothelial cells, 6 months after bare-metal stent (BMS) deployment. Neointimal coverage was classified into not covered (grade 0), covered by a thin layer (grade 1), and buried under neointima (grade 2) groups. (2) In 7 beagles, the relationships between neointimal thickness and ST were examined 6 months after BMS deployment. (3) The NECs on the struts were stained blue in 4 of 25 patients with grade 2 and in 11 of 20 patients with grade 0/1 (P < 0.05). ST was observed in none of the former and in 5 of the latter (P < 0.05). (4) In beagles, neointimal coverage was grade 0/1 when neointimal thickness was 80.2 ± 40.0 µm, whereas grade 2 when thickness was 184 ± 59.4 µm. ST was observed in 9 of 15 struts with neointimal thickness within 100 µm and in one of 17 struts with thickness over 100 µm (P < 0.05). ST arose from damaged NECs covering the stent struts. NECs may have been damaged due to friction between them and struts due to thin interposed neointima which might have acted as a cushion, resulting in ST.

Angioscopic Evaluation of Neointimal Coverage of Coronary Stents

Drug-eluting stents (DES) reduce coronary restenosis significantly; however, late stent thrombosis (LST) occurs, which requires long-term antiplatelet therapy. Angioscopic grading of neointimal coverage of coronary stent struts was established, and it was revealed that neointimal formation is incomplete and prevalence of LST is higher in DES when compared to bare-metal stents. It was also observed that the neointima is thicker and LST is less frequent in paclitaxel-eluting and zotarolimus-eluting stents than in sirolimus-eluting stents. Many new stents were devised and they are now under experimental or clinical investigations to overcome the shortcomings of the stents that have been employed clinically. Endothelial cells are highly anti-thrombotic. Neo-endothelial cell damage is considered to be caused by friction between the cells and stent struts due to the thin neointima between them which might act as a cushion. Therefore, development of a DES that causes an appropriate thickness (around 100 μm) of the neointima is a potential option with which to prevent neo-endothelial cell damage and consequent LST while preventing restenosis.

Acute coronary syndrome: insight from angioscopy

Although the concept of vulnerable plaque has become common, it is still impossible to predict effectively the onset of acute coronary syndrome (ACS). Thin-cap fibroatheroma (TCFA) is regarded as vulnerable from pathological studies and various diagnostic tools have tried to detect TCFA clinically but failed to predict ACS. Because there are so many silent plaque ruptures detected, it is supposed that many vulnerable plaques might have ruptured but not caused ACS. Some factor(s) other than the rupture of vulnerable plaque is required for the onset of ACS. "Vulnerable blood" may be one of them. The thrombogenic potential of blood (ie, vulnerable blood) may play an important and determinant role in the onset of ACS, the process of which will be discussed from the angioscopic point of view.

Coronary angioscopic evaluation for serial changes of luminal appearance after pharmacological and catheter interventions

Although preventive pharmacological therapies effectually reduce the risk of cardiovascular events, acute coronary syndrome (ACS) remains a leading cause of morbidity and mortality in our country, Japan. Disruption of atherosclerotic vulnerable plaques and flow-limiting thrombus formation in non-stent segments of native coronary arteries are considered a main mechanism of ACS. In addition, stent thrombosis originating from implanted metallic coronary stents, so-called vulnerable stents, occasionally appears as ACS in the clinical settings. Coronary angioscopy is a unique imaging modality permitting direct visualization of luminal structures, such as atherosclerotic plaque, thrombus, stent struts, and proliferating neointima. On the basis of accumulated angioscopic findings, intense yellow plaques and stents without neointimal coverage are considered vulnerable plaques and vulnerable stents, respectively. In contrast, morphological disappearance of vulnerable plaques or vulnerable stents by pharmacological and trans-catheter therapies imply stabilization of the plaques or stents. Hence, angioscopic assessment for vulnerability (or stability) of atherosclerotic plaques and implanted stents might be useful for risk classification in the future events of ACS. To evaluate serial changes of coronary lumen after pharmacological and catheter interventions using angioscopy might also provide important information on potential benefits and surrogate endpoints of the therapies and on patients' management.