Vascular healing in high-bleeding-risk patients at 3-month after everolimus-eluting stent versus biolimus A9-coated stent implantation: insights from analysis of optical coherence tomography and coronary angioscopy

The prevalence of high-bleeding-risk (HBR) patients who undergo coronary stenting has been reported as 20-40%. This study sought to assess vascular healing in HBR patients by coronary angioscopy (CAS) and optical coherence tomography (OCT). We prospectively analyzed 38 HBR patients with coronary artery disease who successfully underwent everolimus-eluting stent (EES) implantation (20 patients, 23 lesions) or drug-coated stent (DCS) implantation (18 patients, 18 lesions). Follow-up coronary angiography, CAS, and OCT were planned at 3 months after the procedure. The clinical characteristics and inclusion criteria of HBR were comparable between groups. CAS analysis showed that mean yellow color grade was significantly higher with EES than with DCS (1.33 [1.0, 1.67] vs. 1.0 [0.67, 1.5]; P = 0.04). In contrast, OCT analysis demonstrated that most struts in both groups were well-apposed struts with neointimal coverage (93.9% each; P = 1.00), and percentages of the mean neointimal area were comparable between EES and DCS (4.4 ± 3.5 mm² vs. 4.5 ± 4.1 mm²; P = 0.91). The frequency of uncovered struts was significantly lower with EES than with DCS (2.4% vs. 5.3%; P < 0.001), whereas the frequency of malapposed struts was significantly higher with EES than with DCS (3.5% vs. 0.8%; P < 0.001). During follow-up, no stent thrombosis or major bleeding complications were encountered in either group. Among HBR patients, both EES and DCS demonstrated good vascular healing at 3-month follow-up with some different features in CAS and OCT assessments.

Early and Mid-Term Vascular Responses to Optical Coherence Tomography-Guided Everolimus-Eluting Stent Implantation in Stable Coronary Artery Disease

BACKGROUND

Analysis of pooled clinical data has shown the safety of 3 months of dual antiplatelet therapy with everolimus-eluting cobalt-chromium stents (Co-Cr EESs). This study evaluated early and mid-term vascular responses to Co-Cr EESs in patients with stable coronary artery disease.

METHODS

The Multicenter Comparison of Early and Late Vascular Responses to Everolimus-Eluting Cobalt-Chromium Stent and Platelet Aggregation Studies in Patients With Stable Angina Managed as Elective Case (MECHANISM-Elective) study (NCT02014818) is a multicenter optical coherence tomography (OCT) registry. Enrolled patients were evaluated by OCT immediately after everolimus-eluting stent implantation were prospectively allocated to 1 month (n = 50) or 3 months (n = 50) OCT follow-up and then received a 12-month OCT evaluation. The incidences of intrastent thrombus (IS-Th) and irregular protrusion (IRP) were also assessed.

RESULTS

The percentage of uncovered struts was 6.4% ± 10.3% at 1 month (P < 0.001 vs. postprocedure) and 0.5% ± 0.9% at 12 months (P < 0.001 vs. 1 month). The corresponding values in the 3-month cohort were 2.0% ± 2.5% (P < 0.001 vs. postprocedure) and 0.5% ± 1.5% (P < 0.001 vs. 3 months). The incidence of IS-Th was 32.7% at 1 month, 5.4% at 3 months, and 2.0% at 12 months. IRP was observed in 21.8% of patients post-EES but had totally resolved at 1, 3, and 12 months.

CONCLUSION

Early and mid-term vascular reactions after Co-Cr EES implantation in stable patients with coronary artery disease in the MECHANISM-Elective included dynamic resolution of IS-Th and IRP and rapid decrease in uncovered struts. Thus, EES may allow shortening of dual antiplatelet therapy duration less than 3 months in this patient subset.

Assessment of Vascular Patency and Inflammation with Intravascular Optical Coherence Tomography in Patients with Superficial Femoral Artery Disease Treated with Zilver PTX Stents

PURPOSE

Zilver PTX nitinol self-expanding drug-eluting stent with paclitaxel coating is effective for treatment of superficial femoral artery (SFA) disease. However, as with any stent, it induces a measure of vascular inflammatory response. The current clinical trial (NCT02734836) aimed to assess vascular patency, remodeling, and inflammatory markers with intravascular optical coherence tomography (OCT) in patients with SFA disease treated with Zilver PTX stents.

METHODS

Serial OCT examinations were performed in 13 patients at baseline and 12-month follow-up. Variables evaluated included neointimal area, luminal narrowing, thrombus area, stent expansion as well as measures of inflammation including, peri-strut low-intensity area (PLIA), macrophage arc, neovascularization, stent strut apposition and coverage.

RESULTS

Percentage of malapposed struts decreased from 10.3 ± 7.9% post-intervention to 1.1 ± 2.2% at 12-month follow-up, but one patient showed late-acquired stent malapposition (LASM). The percent of uncovered struts at follow-up was 3.0 ± 4.5%. Average expansion of stent cross-sectional area from baseline to follow-up was 35 ± 19%. The average neointimal area was 7.8 ± 3.8 mm². Maximal luminal narrowing was 61.1 ± 25.0%, and average luminal narrowing was 35.4 ± 18.2%. Average peri-strut low-intensity area (PLIA) per strut was 0.017 ± 0.018 mm². Average number of neovessels per mm of stent was 0.138 ± 0.181. Average macrophage angle per frame at follow-up was 7 ± 11°. Average thrombus area at follow-up was 0.0093 ± 0.0184 mm².

CONCLUSION

At 12-month follow-up, OCT analysis of Zilver PTX stent shows outward remodeling and minimal neointimal growth, but evidence of inflammation including PLIA, neovessels, thrombus and macrophages.

SUMMARY

Thirteen patients with PAD had paclitaxel-coated stents implanted in their SFAs and were then imaged with OCT at baseline and 12-month follow-up. OCT proxy metrics of inflammation were quantified.

Comparison of Strut Coverage at 6 Months by Optical Coherence Tomography With Everolimus-Eluting Stenting of Bare-Metal Stent Restenosis Versus Stenosis of Nonstented Atherosclerotic Narrowing (from the DESERT Study)

Incomplete struts coverage is a predictor of late stent thrombosis after implantation of the drug-eluting stents (DES) in atherosclerotic lesions. The process of struts coverage in DES implanted for bare-metal stent (BMS) restenosis has never been described. Thirty-two patients with stable coronary artery disease were consecutively selected, 11 with BMS restenosis (group A) and 21 with de novo atherosclerotic lesions (group B). All patients underwent everolimus-eluting stent implantation; coronary angiography and optical coherence tomography were performed at 6 months follow-up. Percentage difference in struts coverage between the 2 groups was the primary end point. A total of 85,773 struts (17,891 in group A and 67,882 in group B) were analyzed: compared with group B, the percentage of uncovered stent struts was significantly lower in group A (2.6% vs 4.8%; p <0.0001). In group A, DES struts protruding out of BMS were more uncovered (5.0% vs 1.9%; p <0.0001) and malapposed (4.1% vs 2.1%; p <0.0001) compared with overlapping struts. In conclusion, when DES are implanted to treat BMS restenosis, struts coverage at 6 months follow-up is more complete compared with DES implanted in atherosclerotic lesions.

Assessment of vascular response after drug-eluting stents implantation in patients with diabetes mellitus: an optical coherence tomography sub-study of the J-DESsERT

Even in the drug-eluting stent era, diabetes mellitus (DM) patients have high incidences of restenosis and repeat revascularization after percutaneous coronary intervention. The aim of this study was to compare vascular response after stent implantation between sirolimus-eluting stent (SES) and paclitaxel-eluting stent (PES) by using optical coherence tomography (OCT) in DM patients as well as in non-DM patients. In the Japan-Drug Eluting Stents Evaluation; a Randomized Trial (J-DESsERT), the OCT sub-study enrolled 75 patients who underwent 8 months follow-up imaging after SES or PES implantation. Mean neointimal hyperplasia (NIH) thickness was significantly thinner in SES than PES in the DM group (77 ± 47 vs. 201 ± 114 μm, p < 0.001) and in the non-DM group (84 ± 37 vs. 212 ± 128 μm, p < 0.001). Unevenness of NIH thickness in longitudinal axis was significantly smaller in SES than PES in the DM group (348 ± 191 vs. 726 ± 385 μm, p < 0.001) and in the non-DM group (344 ± 174 vs. 679 ± 314 μm, p < 0.001). The percentage of uncovered struts was significantly greater in SES than PES in the DM group (24 ± 4 vs. 9 ± 14 %, p < 0.001) and in the non-DM group (16 ± 16 vs. 3 ± 4 %, p = 0.002). Compared with PES, SES showed more potent NIH inhibition in DM patients as well as in non-DM patients.

Vascular response to drug-eluting stent with biodegradable vs. durable polymer. Optical coherence tomography substudy of the NEXT

BACKGROUND

The aim of the present study was to compare vascular healing response between everolimus-eluting stent (EES) and biolimus-eluting stent (BES) using optical coherence tomography (OCT).

METHODS AND RESULTS

In the NOBORI Biolimus-Eluting Versus XIENCE V/PROMUS Everolimus-Eluting Stent Trial (NEXT), a formal OCT substudy investigated 91 patients (55 EES-treated lesions in 48 patients and 51 BES-treated lesions in 43 patients) with 8-12 months follow-up imaging at 18 centers. A total of 980 frames with 8,996 struts in EES and 907 frames with 8,745 struts in BES were analyzed. Mean neointima thickness in EES and BES was 105±82μm and 91±80μm, respectively (P<0.001). With regard to stent-treated lesions, the percentage of struts not covered by neointima (3±7% vs. 9±10%, P<0.001) and the frequency of stent-treated lesions with any uncovered struts (n=28, 51% vs. n=42, 82%; P<0.001) were significantly lower in EES compared with BES. In addition, the percentage of malapposed struts (0.2±0.8% vs. 1.3±2.8%, P=0.006) and the frequency of stent-treated lesions with any malapposed struts (n=6, 11% vs. n=14, 27%; P=0.028) were significantly lower in EES compared with BES.

CONCLUSIONS

Incomplete vascular healing characterized by the presence of struts not covered by neointima and malapposed struts was less common in EES compared with BES.

Comparison of paclitaxel-eluting vs. everolimus-eluting stents implanted simultaneously in different lesions of the same coronary artery: 12-month follow-up with optical coherence tomography

AIMS

Optical coherence tomography (OCT) allows a detailed assessment of intimal coverage and strut apposition which are well known substrates for late thrombosis. This study sought to assess and compare long-term coverage and apposition of PES and EES implanted in different lesions of the same coronary artery (and in the same patient).

METHODS AND RESULTS

A total of 30 patients were included. In these patients PES and EES were implanted in the same vessel in two similar lesions. The selection of the stent for each lesion was random. At 12 months, 30 PES were examined analysing 154±90 struts/stents and 30 EES analysing 158±72 struts/stents. The proportion of uncovered struts was 0.8±1.3% for EES and 1.5±2.9% for PES (p=0.3), and the proportion of malapposed struts was 1.25±2.1% and 0.98±2%, respectively (p=0.2). A pooled analysis was performed using the random effects model, given the significant heterogeneity found, which did not show significant differences between EES and PES for non-coverage (RR 0.73, 95% CI: 0.32-1.67) or malapposition (RR 1.60, 95% CI: 0.56-4.61). The presence of non-coverage in malapposed struts was 62% with PES and 15% with EES (p<0.0001), the maximal malapposition area being significantly larger with PES (0.6±0.3 vs. 0.25±0.2 mm², p=0.001).

CONCLUSIONS

In highly matched conditions, with PES and EES implanted in the same artery, both DES showed a comparable degree of intimal coverage and apposition at one-year follow-up. A smaller area of malapposition with non-covered struts was found with EES.

One-year head to head comparison of the neointimal response between sirolimus eluting stent with reservoir technology and everolimus eluting stent: an optical coherence tomography study

OBJECTIVE

to compare the vascular healing process between the sirolimus-eluting NEVO and the everolimus-eluting Xience stent by optical coherence tomography (OCT) at 1-year follow-up.

BACKGROUND

Presence of durable polymer on a drug-eluting metallic stent may be the basis of an inflammatory reaction with abnormal healing response. The NEVO stent, having a bioresorbable polymer eluted by reservoir technology, may overcome this problem.

METHODS

All consecutive patients, who received NEVO or Xience stent implantation between September 2010 and October 2010 in our institution, were included. Vascular healing was assessed at 1-year as percentage of uncovered struts, neointimal thickness (NIT), in-stent/stent area obstruction and pattern of neointima.

RESULTS

A total 47 patients (2:1 randomization, n = 32 NEVO, n = 15 Xience) were included. Eighteen patients underwent angiographic follow-up (eight patients with nine lesions for NEVO vs. 10 patients with 11 lesions for Xience). The angiographic late loss was numerically higher but not statistically different in NEVO compared with Xience treated lesions (0.38 ± 0.47 mm vs. 0.18 ± 0.27 mm; P = 0.171). OCT analysis of 4,912 struts demonstrated similar rates of uncovered struts (0.5 vs. 0.7%, P = 0.462), higher mean NIT (177.76 ± 87.76 µm vs. 132.22 ± 30.91 µm; P = 0.170) and in stent/stent area obstruction (23.02 ± 14.74% vs. 14.17 ± 5.94%, P = 0.120) in the NEVO as compared with Xience.

CONCLUSION

The NEVO stent with a reservoir technology seems to exhibit more neointimal proliferation as compared to Xience stent. The findings of our study, which currently represent the unique data existing on this reservoir technology, would need to be confirmed in a large population.

Quantitative and qualitative changes in DES-related neointimal tissue based on serial OCT

OBJECTIVES

The study evaluated serial quantitative and qualitative changes in vascular responses to drug-eluting stents (DES) using optical coherence tomography (OCT).

BACKGROUND

Serial changes in stent strut coverage and neointima characteristics in DES-treated lesions have not been sufficiently investigated using OCT.

METHODS

Serial OCT was performed in 72 patients with 76 DES-treated lesions at 9 months and 2 years after DES implantation (sirolimus-eluting stent, n = 23; paclitaxel-eluting stent, n = 20; zotarolimus-eluting stent, n = 25; everolimus-eluting stent, n = 8). Serial changes in quantitative parameters (neointimal thickness, stent strut coverage, and apposition at each strut) and qualitative characteristics of the neointima were evaluated.

RESULTS

Mean neointimal thickness significantly increased from 164 μm to 214 μm between 9 months and 2 years (p < 0.001), and the percentage of uncovered stent struts significantly decreased (from 4.4% to 2.3%, p < 0.001). Completely covered lesions were more frequently observed at 2 years (44.7% vs. 59.2%, p = 0.07). However, the percentage of malapposed struts (0.6% vs. 0.9%, p = 0.24) and incidence of intracoronary thrombi (10.5% vs. 9.2%, p > 0.99) were similar. On qualitative evaluation of neointimal morphology, lipid-laden neointima (27.6% vs. 14.5%, p = 0.009) and thin-cap neoatheroma (13.2% vs. 3.9%, p = 0.07) were more frequently detected at 2-year follow-up compared with 9 months. In matched cross-sectional evaluation, the change of neointimal morphology from homogeneous to heterogeneous or lipid-laden pattern was observed in 23 (30.3%) of 76 lesions. There was a significant increase in percent neointimal hyperplasia cross-sectional area in those lesions.

CONCLUSIONS

This OCT study suggested that neointimal coverage improved from 9 months to 2 years without significant changes in the incidence of malapposed struts and intracoronary thrombus. Additionally, in-stent neoatherosclerosis including transformation to lipid-laden neointima might progress during extended follow-up periods after DES implantation.

Natural consequence of post-intervention stent malapposition, thrombus, tissue prolapse, and dissection assessed by optical coherence tomography at mid-term follow-up

Aims

We performed this study to clarify natural consequences of abnormal structures (stent malapposition, thrombus, tissue prolapse, and stent edge dissection) after percutaneous coronary intervention (PCI).

Methods and results

Thirty-five patients treated with 40 drug-eluting stents underwent serial optical coherence tomography (OCT) imaging immediately after PCI and at the 8-month follow-up. Among a total of 73 929 struts in every frame, 431 struts (26 stents) showed malapposition immediately after PCI. Among these, 49 remained malapposed at the follow-up examination. The mean distance between the strut and vessel wall (S–V distance) of persistent malapposed struts on post-stenting OCT images was significantly longer than that of resolved malapposed struts (342 ± 99 vs. 210 ± 49 μm; P <0.01). Based on receiver-operating characteristic curve analysis, an S–V distance ≤260 µm on post-stenting OCT images was the corresponding cut-off point for resolved malapposed struts (sensitivity: 89.3%, specificity: 83.7%, area under the curve = 0.884). Additionally, 108 newly appearing malapposed struts were observed on follow-up OCT, probably due to thrombus dissolution or plaque regression. Thrombus was observed in 15 stents post-PCI. Serial OCT analysis revealed persistent thrombus in 1 stent, resolved thrombus in 14 stents, and late-acquired thrombus in 8 stents. Tissue prolapse observed in 38 stents had disappeared at the follow-up. All eight stent edge dissections were repaired at the follow-up.

Conclusion

Most cases of stent malapposition with a short S–V distance, thrombus, tissue prolapse, or minor stent edge dissection improved during the follow-up. These OCT-detected minor abnormalities may not require additional treatment.

Optical Coherence Tomography Imaging: Novel Insights into the Vascular Response After Coronary Stent Implantation

Optical coherence tomography (OCT) is a high-resolution imaging technique that is increasingly used for intracoronary imaging to characterize coronary atherosclerotic plaques and vascular responses after coronary stent implantation. Introduction of optical frequency-domain imaging (OFDI; second generation OCT) has simplified practical use of this novel imaging modality resulting in a more widespread availability in interventional cardiology. Here we highlight recent insights into the acute and chronic vascular response after coronary stent implantation by OCT imaging. OCT provides cross-sectional images with approximately 10-fold higher resolution as compared to intravascular-ultrasound (IVUS), allowing for precise evaluation of tissue coverage and malapposition of coronary stent struts. More than 30 studies using OCT to compare vascular responses to different stents have now been reported. Recent studies have examined the relation between OCT-image characteristics and tissue composition around stent struts. OCT is used for evaluation of novel stent concepts, such as bioengineered stents and bioabsorbable stents, where it provides more accurate information than IVUS. While intracoronary OCT imaging is further developed, including faster 3D-OCT-image-reconstruction, larger OCT studies/registries with standardized analysis will provide more insights into clinical implications of observations from OCT-imaging after coronary stent implantation.

Intracoronary optical diagnostics current status, limitations, and potential

Optical coherence tomography (OCT), is a novel intravascular imaging modality analogous to intravascular ultrasound but uses light instead of sound. This review details the background, development, and status of current investigation using OCT, and discusses advantages, limitations, and likely future developments. It provides indications for possible future clinical use, and places OCT in the context of current intravascular imaging in what is a rapidly changing field of investigation.

Optical coherence tomography evaluation of drug-eluting stents: a systematic review

AIMS

We performed a systematic review of studies reporting stent strut coverage and malapposition post implantation of different drug-eluting stent (DES), as assessed by optical coherence tomography (OCT).

METHODS

A review of publications and online databases in May 2011 retrieved 33 published studies reporting stent strut coverage and malapposition post-DES implantation using OCT: 24 for sirolimus-eluting stents (SES), 13 for paclitaxel-eluting stents (PES), 10 for zotarolimus-eluting stents (ZES), and two for everolimus-eluting stents (EES). The follow-up duration ranged from 3 months to 4 years. Stent strut coverage and malapposition were compared between DES at various time intervals post implantation.

RESULTS

Significant differences in stent strut coverage and malapposition exist between various DES. The SES had the highest frequency of uncovered struts at 3, 6, 9, and 12 months (13.1%, 10.9%, 8.1%, and 7.5%, respectively), followed by PES (5.5%, 4.4%, and 5.7% at 6, 9, and 12 months, respectively) and ZES (0.7%, 0%, and 0.5% at 3, 6, and 9 months, respectively) (P < 0.001 for all comparisons between stents). Only two studies reported 3.1% uncovered struts at 9 months with the EES. Stent strut malapposition at 6, 9, and 12 months was highest with SES (3.2%, 2.2%, and 1.2%, respectively) followed by PES (1.6%, 1.3%, and 0.9%, respectively), EES (0.46% at 9 months), and ZES (0.7% and 0.1% at 6 and 9 months, respectively).

CONCLUSIONS

SES had the highest rates of uncovered struts and malapposition, followed by PES and ZES. Such differences may explain the different clinical outcomes between various DES. © 2012 Wiley Periodicals, Inc.

Impact of positive peri-stent vascular remodeling after sirolimus-eluting and paclitaxel-eluting stent implantation on 5-year clinical outcomes: intravascular ultrasound analysis from the Poststent Optimal Stent Expansion Trial multicenter randomized trial

BACKGROUND

Positive peri-stent vascular remodeling (PPVR) after drug-eluting stent (DES) implantation is an important mechanism of late-acquired stent malapposition (LASM).

METHODS AND RESULTS

A total of 226 patients (sirolimus-eluting stent [SES], n=105; paclitaxel-eluting stent [PES], n=121) from the Poststent Optimal Stent Expansion Trial who underwent a post-intervention and 9-month follow-up intravascular ultrasound were followed clinically for 5 years. PPVR was arbitrarily defined as a >10% increase in the external elastic membrane volume index at follow-up. PPVR and LASM occurred more frequently with SESs than with PESs. The 5-year rate of major adverse cardiac events was lower with SES than with PES (10.7% vs. 23.2%, P=0.002). The late and very late stent thrombosis (ST) rate was similar between the 2 DES types, but it was higher in patients with PPVR than in those without PPVR (8.8% vs. 1.3%, P=0.009) regardless of the DES type. Early discontinuation (<1 year) of dual antiplatelet therapy (DAPT; hazard ratio [HR], 24.14; 95% confidence interval [CI]: 4.90-118.87; P<0.001), PPVR (HR, 14.94; 95%CI: 1.85-120.46; P=0.011), LASM (HR, 8.01; 95%CI: 1.93-33.16; P=0.004), and stent length (HR, 1.14; 95%CI: 0.98-1.32 per mm; P=0.078) were associated with increased risk of late and very late ST.

CONCLUSIONS

PPVR and LASM development after DES implantation, along with early discontinuation of DAPT and longer stent length, are important risk factors of late and very late ST.

Optical coherence tomography: from research to practice

Optical coherence tomography (OCT) is a high-resolution imaging technique with great versatility of applications. In cardiology, OCT has remained hitherto as a research tool for characterization of vulnerable plaques and evaluation of neointimal healing after stenting. However, OCT is now successfully applied in different clinical scenarios, and the introduction of frequency domain analysis simplified its application to the point it can be considered a potential alternative to intravascular ultrasound for clinical decision-making in some cases. This article reviews the use of OCT for assessment of lesion severity, characterization of acute coronary syndromes, guidance of intracoronary stenting, and evaluation of long-term results.

Natural history of stent edge dissection, tissue protrusion and incomplete stent apposition detectable only on optical coherence tomography after stent implantation – preliminary observation –

BACKGROUND

The clinical impact of stent edge dissection, tissue protrusion, and incomplete stent apposition (ISA) after stent implantation, detectable only on optical coherence tomography (OCT), is still unknown because the natural course has not been investigated.

METHODS AND RESULTS

All consecutive patients with angina pectoris in whom both intravascular ultrasound (IVUS) and OCT were performed immediately after stenting and at follow-up were included in the present study. The natural history of OCT-detected stent edge dissection, tissue protrusion, and ISA during follow-up was investigated. A total of 36 patients with 39 lesions was analyzed. At baseline, OCT showed 12 stent edge dissections, 25 tissue protrusions, and 8 ISAs, whereas IVUS demonstrated 6 stent edge dissections, 5 tissue protrusions, and 3 ISAs. All IVUS findings were clearly visualized on OCT. The maximum length of dissection flap and depth of ISA visualized on OCT were significantly shorter than those visualized on IVUS. Maximum length of tissue protrusion tended to be smaller on OCT than on IVUS. At follow-up (median 188 days), all findings noted on OCT were healed or resolved without any restenosis or thrombus formation.

CONCLUSIONS

Acute findings after stenting, such as edge dissection, tissue protrusion, and ISA, detectable only on OCT, tended to be smaller than those seen on both OCT and IVUS. The majority of OCT-detected acute findings resolved completely at follow-up.

Spatial distribution and temporal evolution of scattering centers by optical coherence tomography in the poly(L-lactide) backbone of a bioresorbable vascular scaffold

BACKGROUND

Scattering centers (SC) are often observed with optical coherence tomography (OCT) in some struts of bioresorbable vascular scaffolds (BVS). These SC might be caused by crazes in the polymer during crimp-deployment (more frequent at inflection points) or by other processes, such as physiological loading or hydrolysis (eventually increasing with time). The spatial distribution and temporal evolution of SC in BVS might help to understand their meaning.

METHODS AND RESULTS

Three patients were randomly selected from 12 imaged with Fourier-domain OCT at both baseline and 6 months in the ABSORB cohort B study (NCT00856856). Frame-by-frame analysis of the SC distribution was performed using spread-out vessel charts, and the results from baseline and 6 months were compared. A total of 4,328 struts were analyzed. At baseline and follow-up all SC appeared at inflection points. No significant difference was observed between baseline and 6 months in the number of SC struts (14.9 vs. 14.5%, P=0.754) or in the distribution of SC. The proportion and distribution of SC did not vary substantially among the patients analyzed.

CONCLUSIONS

The SC observed in OCT imaging of the BVS are located exclusively at inflection points and do not increase with time. These findings strongly suggest that SC are caused by crazes in the polymer during crimp-deployment, ruling out any major role of hydrolysis or other time-dependent processes.

Current status of optical coherence tomography

Optical coherence tomography (OCT) is a novel imaging technology based on low-coherence interferometry that use near-infrared light in real-time, and allows cross-sectional in-situ visualization of the vessel wall at the microscopic level. OCT provides 10-fold higher resolution than intravascular ultrasound which is currently the most used modality for intra-coronary imaging. OCT offers the obvious advantages when characterizing precise plaque microstructure and distinguishing various type of plaques. OCT is also being assessed for its potential role in the understanding of neointimal coverage, vascular healing and the progression of atherosclerosis in coronary vasculature after stenting on the micron scale. These unique capabilities could be helpful in guiding coronary management and interventions. Recent improvement in next generation OCT technology, such as frequency-domain OCT, will allow for a simple imaging procedure, providing more useful information and complementing other modalities on both clinical and research applications for the cardiologists.

Assessment of coronary stent by optical coherence tomography, methodology and definitions

Optical coherence tomography has emerged as a powerful tool for stent assessment, and in a short time, has become the modality of choice for studying stent and vascular interactions in vivo. In this review, we discuss qualitative and quantitative parameters used for stent assessment by OCT. Various qualitative/quantitative variables of stent assessment are discussed in the perspective of the clinical and research values of each of them.

Optical coherence tomography: a new imaging modality for plaque characterization and stent implantation

Optical coherence tomography (OCT) is a novel, catheter-based, invasive imaging system based on near-infrared light with high image resolution (15-20 μm). The system allows for unparalleled imaging of the coronary artery lumen, plaque characterization, assessment of coronary stent strut apposition, neointimal coverage, vascular proliferative response, complications such as focal dissection or thrombus formation, and insight into the time course of stent endothelization. This review will describe the currently available developments in OCT technology and its application in both the clinical and research arenas.

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.

STELLIUM 1: First-in-man follow-up evaluation of bioabsorbable polymer-coated paclitaxel-eluting stent

BACKGROUND

Durable polymers used for first-generation drug-eluting stents (DES) potentially contribute to persistent inflammation and late DES thrombosis. The vascular response to the Stellium stent, which is coated with an absorbable polymer for slow release of low-dose paclitaxel, was evaluated in the present study.

METHODS AND RESULTS

The 37 patients with stable angina were implanted with 47 Stellium stents. Quantitative coronary angiography (QCA) was performed at baseline, and QCA and optical coherence tomography (OCT) were performed at 6 months post-implant. The primary endpoint was major adverse cardiac events (MACE). At 6 months, 1 case of MACE occurred because of total occlusion of a protected left main artery. In-stent and segment binary restenosis rates were both 0%. In-stent late loss was 0.19 ± 0.54 mm. Altogether, 5,564 struts were visualized by OCT and mean neointimal thickness was 150.03 ± 146.36 µm. The number of well-apposed struts with and without neointima overlay was 5,135 (92.29%) and 396 (7.12%), respectively. Peri-strut low intensity was observed in 518 struts (9.31%).

CONCLUSIONS

This first-in-man study of the Stellium stent shows the promising possibility of bioabsorbable polymeric surface coating paclitaxel-eluting stents out to 6 months. The low rate of peri-strut low intensity suggests low cellular toxicity of the Stellium stent compared with the first-generation DES.