Peri-strut low-intensity areas in optical coherence tomography correlate with peri-strut inflammation and neointimal proliferation: an in-vivo correlation study in the familial hypercholesterolemic coronary swine model of in-stent restenosis

Plaque burden is associated with minimal intimal coverage following drug-eluting stent implantation in an adult familial hypercholesterolemia swine model

Safety and efficacy of coronary drug-eluting stents (DES) are often preclinically tested using healthy or minimally diseased swine. These generally show significant fibrotic neointima at follow-up, while in patients, incomplete healing is often observed. The aim of this study was to investigate neointima responses to DES in swine with significant coronary atherosclerosis. Adult familial hypercholesterolemic swine (n = 6) received a high fat diet to develop atherosclerosis. Serial OCT was performed before, directly after, and 28 days after DES implantation (n = 14 stents). Lumen, stent and plaque area, uncovered struts, neointima thickness and neointima type were analyzed for each frame and averaged per stent. Histology was performed to show differences in coronary atherosclerosis. A range of plaque size and severity was found, from healthy segments to lipid-rich plaques. Accordingly, neointima responses ranged from uncovered struts, to minimal neointima, to fibrotic neointima. Lower plaque burden resulted in a fibrotic neointima at follow-up, reminiscent of minimally diseased swine coronary models. In contrast, higher plaque burden resulted in minimal neointima and more uncovered struts at follow-up, similarly to patients' responses. The presence of lipid-rich plaques resulted in more uncovered struts, which underscores the importance of advanced disease when performing safety and efficacy testing of DES.

Temporal Course of Vascular Response After Fluoropolymer Paclitaxel-Eluting Stent Implantation for Femoropopliteal Artery Lesions

BACKGROUND

Limited data are available regarding the vascular response after fluoropolymer paclitaxel-eluting stent (FP-PES) implantation. This study sought to assess the vascular response at 6 and 12 months after FP-PES implantation for femoropopliteal artery lesions using serial optical coherence tomography (OCT) examination.Methods and Results:From the IMPERIAL trial, this study evaluated 10 de novo femoropopliteal lesions treated with FP-PES. The primary study endpoint was neointimal tissue coverage at a 6- and 12-month follow up, as assessed by serial OCT examination. The incidence of peri-strut low-intensity area (PLIA) and extra-stent lumen (ESL) was also assessed. A total of 203 matched cross-sectional images were evaluated at 6 and 12 months (5,615 and 5,763 struts, respectively). From 6 to 12 months, the mean neointimal thickness tended to increase from 198 µm to 233 µm, with a significant reduction in the incidence of malapposed struts (0.59% vs. 0.28%, P=0.039). Conversely, uncovered struts and PLIA were more frequently observed at 12 months (4.4% vs. 7.8%, P=0.01; 12.7% vs. 21.0%, P<0.001, respectively). The ESL area significantly increased over time without any difference in its incidence (0.24±0.32 mm²vs. 0.38±0.36 mm², P=0.009).

CONCLUSIONS

Neointimal proliferation was markedly inhibited from 6 to 12 months after FP-PES implantation, whereas the incidence of uncovered struts and PLIA significantly increased over time with the enlargement of ESL.

Clinical outcome of biodegradable polymer sirolimus-eluting stent and durable polymer everolimus-eluting stent in patients with diabetes

Background

Diabetes mellitus is a risk for increased incidence of adverse clinical events after percutaneous coronary intervention. However, the difference in the incidence of adverse clinical events according to stent type in patients with diabetes remains to be elucidated. In the present study, we aimed to compare the clinical outcomes between patients treated with the biodegradable polymer sirolimus-eluting stents (BP-SES) and the durable polymer everolimus-eluting stents (DP-EES) among patients with diabetes.

Methods

Among 631 lesions in 510 consecutive patients treated with either BP-SES or DP-EES, 165 lesions in 141 patients with diabetes mellitus and stable angina pectoris were identified and classified into the BP-SES group (48 lesions in 44 patients) and the DP-EES group (117 lesions in 100 patients). The incidence of adverse clinical events after stent implantation was compared between the 2 groups.

Results

There was no significant difference in the prevalence of conventional risk factors, lesion characteristics, and procedural characteristics between the 2 groups. During median 386 [334–472] days follow-up, the incidence of target lesion revascularization (11.4 vs. 2.0%, p = 0.003) and device-oriented clinical endpoint (13.6 vs. 6.0%, p = 0.035) in the BP-SES group was significantly greater than that in the DP-EES group. A univariate model demonstrated that the BP-SES usage was significantly associated with the higher incidence of target lesion revascularization (odds ratio, 6.686; 95% confidence interval, 1.234–36.217; p = 0.028).

Conclusion

BP-SES was associated with the greater incidence of TLR than the DP-EES in patients with diabetes mellitus. Further studies with larger cohorts and longer follow-up are required to confirm the present results.

Influence of neoatherosclerosis on prognosis and treatment response in patients with in-stent restenosis

INTRODUCTION AND OBJECTIVES

Neoatherosclerosis is one of the causes of in-stent restenosis (ISR). Our objective was to evaluate the influence of neoatherosclerosis on prognosis and treatment response in patients with ISR.

METHODS

This is a pooled analysis of the optical coherence tomography (OCT)-substudies of 2 multicenter, randomized clinical trials, RIBS IV and V, comparing treatment with paclitaxel-coated balloon vs everolimus-eluting stent in patients with ISR. OCT evaluation was performed at baseline and at 6 to 9 months. Neoatherosclerosis was defined in baseline OCT as neointima with calcified or lipid content. We evaluated the angiographic and OCT results at 6 to 9 months and the occurrence of major adverse cardiovascular events at 3 years of follow-up in patients with and without neoatherosclerosis treated with paclitaxel-coated balloon or everolimus-eluting stents.

RESULTS

Sixty-four patients underwent OCT at the time of the index procedure. Neoatherosclerosis was documented in 23 (36%) lesions. Angiographic follow-up at 6 to 9 months showed no differences in restenosis [5 (24%) vs 6 (15%) P=.49], minimum lumen diameter (1.79±0.7 vs 1.94±0.6mm; P=.41) or late loss (0.33±0.7 vs 0.15±0.5; P=.34) in patients with and without neoatherosclerosis, respectively. Follow-up OCT confirmed the absence of differences in quantitative parameters and the characteristics of tissue coverage between the 2 groups. At 3 years of follow-up, the major adverse cardiovascular events rate was 3 (13%) vs 5 (12%) in the neoatherosclerosis and nonneoatherosclerosis groups (HR, 0.94; 95%CI, 0.22-3.93; P=.93).

CONCLUSIONS

In this limited study population, OCT-defined neoatherosclerosis did not seem to influence acute and long-term outcomes in patients randomized to paclitaxel-coated balloon or everolimus-eluting stents for ISR.

Repetitive restenosis in a biodegradable polymer sirolimus-eluting stent with hypersensitivity reaction: a case report

Background 

Hypersensitivity reaction is a classic cause of in-stent restenosis (ISR) in coronary stents, typically reported in bare-metal stents and first-generation drug-eluting stents. Biodegradable polymer sirolimus-eluting stent (BP-SES) was developed with the concept of biocompatibility, and there has been no report of ISR of BP-SES with hypersensitivity reaction.

Case summary 

An 81-year-old woman presented with ST-elevation acute inferior myocardial infarction. Primary percutaneous coronary intervention was performed for the culprit lesion in the left circumflex artery with a permanent polymer everolimus-eluting stent (PP-EES), followed by BP-SES implantation in the left anterior descending artery. Eight months later, coronary angiography showed total occlusion of the PP-EES and diffuse ISR in the BP-SES, treated with a paclitaxel-eluting balloon. Fluorodeoxyglucose with positron emission tomography showed increased uptake around the BP-SES, and cardiac magnetic resonance imaging revealed a late gadolinium-enhanced area around both stents. Four months later, she developed re-ISR in the BP-SES, and optical coherence tomography demonstrated diffuse-layered neointimal hyperplasia with microvascularization and peri-strut low-intensity area. She was successfully treated with coronary artery bypass grafting.

Discussion 

Our case demonstrated repetitive short-term ISR of the BP-SES. Observation by both intravascular and non-invasive imaging modalities suggested the presence of hypersensitivity reaction localized in the stent. Hypersensitivity to the metal may be a possible mechanism because both stents are composed of L605 cobalt-chromium alloy. This is the first report of ISR of a BP-SES with hypersensitivity reaction. Non-invasive imaging can be useful to assess this critical condition.

OCT-assessment of scaffold resorption: Analysis of strut intensity by a new resorption index for poly-l-lactic acid bioresorbable vascular scaffolds

BACKGROUND

The aim of this study was to analyze individual differences in resorption of bioresorbable vascular scaffolds (BRS) through optical coherence tomography (OCT) analysis and to identify factors potentially influencing the resorption process.

METHODS

Between April 2016 and July 2017 clinically driven invasive coronary angiography and OCT examinations were performed in 36 patients who had previously been treated with a total of 48 BRS (ABSORB BVS, Abbott Vascular, Santa Clara, CA). For each scaffold, a new BRS-RESORB-INDEX (BRI) was calculated.

RESULTS

The mean time interval since implantation was 789 ± 321 days. In OCT, BRS struts remained detectable in all 48 BRS. Normalized light intensity as a marker for the resorption of BRS struts increased with time in a linear fashion (Spearman Rho: p < .001, correlation coefficient = .90; R² [linear] = .91). Multivariable analysis identified diabetes (BRI of patients with diabetes vs. patients without diabetes: 0.34 ± 0.13 vs. 0.58 ± 0.22; p = .002) and presence of Peri-strut low intensity areas (PSLIA, BRI of 10 patients with PSLIA vs. 26 patients without PSLIA: 0.44 ± 0.21 vs. 0.61 ± 18; p = .027) as independent predictors for a prolonged BRS resorption, whereas the resorption rate in ACS patients (STEMI, NSTEMI, and unstable angina; n = 13) was significantly higher as compared to patients without ACS (0.62 ± 0.17 vs. 0.43 ± 0.24; p = .012).

CONCLUSION

In humans, BRS resorption rate is significantly influenced by numerous factors. Our data suggest that diabetes and PSLIA are associated with a prolonged resorption process, whereas in ACS patients, BRS resorption appears to be significantly faster.

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.

Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

Bioresorbable scaffold (BRS) technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique.

Possible mechanical causes of scaffold thrombosis: insights from case reports with intracoronary imaging

The advent of intracoronary stents has greatly increased the safety and applicability of percutaneous coronary interventions. One of the drawbacks of drug-eluting stents (DES) is the increased risk of late and very late stent thrombosis (ST). It was anticipated that the risks of ST after DES implantation would be solved with the advent of fully biodegradable scaffolds, which offer the possibility of transient scaffolding of the vessel to prevent acute vessel closure and recoil while also transiently eluting an antiproliferative drug to counteract constrictive remodelling and excessive neointimal hyperplasia. In spite of the enthusiasm for the concept of bioresorbable scaffolds, current clinical data on the Absorb bioresorbable vascular scaffold (BVS) have generated concerns about scaffold thrombosis (ScT) in both the early and late phases. However, the causes of ScT in both the early and late phases have yet to be fully elucidated. This article seeks to provide insights into the possible mechanical causes of ScT in the early and late phases with data stemming from intracoronary imaging (intravascular ultrasound and optical coherence tomography) of the currently published ScT cases following the implantation of BVS and reviews the practical recommendations for implantation of the BVS made by a group of experts.

Evaluation of Early Healing Profile and Neointimal Transformation Over 24 Months Using Longitudinal Sequential Optical Coherence Tomography Assessments and 3-Year Clinical Results of the New Dual-Therapy Endothelial Progenitor Cell Capturing Sirolimus-Eluting Combo Stent

Background—

Current monotherapy drug-eluting stents are associated with impaired healing, neoatherosclerosis, and late stent thrombosis. The healing profile and neointimal transformation of the first dual-therapy endothelial progenitor cell–capturing sirolimus-eluting stent are unknown.

Methods and Results—

In this prospective, single-center study, 61 patients treated with the Combo stent had optical coherence tomography at baseline, early follow-up (4 monthly groups in a 1:2:2:1 ratio from 2 to 5 months), 9 months, and 24 months. Optical coherence tomography early strut coverage increased from 77.1% to 92.5% to 92.7% to 94.9% between 2 and 5 months. At 9 months, the major adverse cardiac event rate was 1.64%, and angiographic in-stent late loss was 0.24 mm (0.08–0.40). The 36-month major adverse cardiac event rate was 3.3%. From 9 to 24 months, neointimal regression was confirmed by optical coherence tomography: neointimal thickness (median [first quartile and third quartile]), 0.14 mm (0.08 and 0.21) versus 0.12 mm (0.07 and 0.19), P <0.001; neointimal volume, 29.9 mm 3 (22.1 and 43.2) versus 26.2 mm 3 (19.6 and 35.8), P =0.003; and percent neointimal volume, 17.8% (12.2 and 21.2) versus 15.7% (11.2 and 19.4), P =0.01. No definite or probable late stent thrombosis was recorded.

Conclusions—

With additional endothelial progenitor cell–capturing technology, the Combo stent exhibits a unique late neointimal regression (from 9 to 24 months) that has not been reported in any drug-eluting stents, translating into good 36-month clinical results with minimal restenosis and no late stent thrombosis. This is the first study testing the concept of using a longitudinal sequential optical coherence tomography protocol to continuously document early healing profile and late neointimal transformation, predicting long-term outcomes of a new novel stent platform.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifiers: NCT01274234, NCT01756807, and NCT02263313.

Optical Coherence Tomography Findings in Bioresorbable Vascular Scaffolds Thrombosis

BACKGROUND

Everolimus-eluting bioresorbable vascular scaffolds have been developed to improve late outcomes after coronary interventions. However, recent registries raised concerns regarding an increased incidence of scaffold thrombosis (ScT). The mechanism of ScT remains unknown.

METHODS AND RESULTS

The present study investigated angiographic and optical coherence tomography findings in patients experiencing ScT. Fifteen ScT (14 patients, 79% male, age 59±10 years) occurred at a median of 16 days (25%-75% interquartile range: 1-263 days) after implantation. Early ScT (<30 days) occurred in 8 cases (53%). Possible causal factors in these patients included insufficient platelet inhibition in 2 cases and procedural factors (scaffold underexpansion, undersizing, or geographical miss) in 4 cases. No obvious cause could be found in 2 early ScT. In late (>1 month) and very late (>1 year) ScT (respectively, 5 and 2 cases), 5 scaffolds showed intimal neovessels or marked peristrut low-intensity areas. Scaffold fractures were additionally found in 2 patients, and scaffold collapse was found in 1 patient with very late ScT. Extensive strut malapposition was the presumed cause for ScT in 1 case. One scaffold did not show any morphological abnormality. Thrombectomy specimens were analyzed in 3 patients and did not demonstrate increased numbers of inflammatory cells.

CONCLUSIONS

The mechanisms of early ScT seem to be similar to metallic stents (mechanical and inadequate antiplatelet therapy). The predominant finding in late and very late ScT is peristrut low-intensity area.

Modelling the Impact of Atherosclerosis on Drug Release and Distribution from Coronary Stents

Although drug-eluting stents (DES) are now widely used for the treatment of coronary heart disease, there remains considerable scope for the development of enhanced designs which address some of the limitations of existing devices. The drug release profile is a key element governing the overall performance of DES. The use of in vitro, in vivo, ex vivo, in silico and mathematical models has enhanced understanding of the factors which govern drug uptake and distribution from DES. Such work has identified the physical phenomena determining the transport of drug from the stent and through tissue, and has highlighted the importance of stent coatings and drug physical properties to this process. However, there is limited information regarding the precise role that the atherosclerotic lesion has in determining the uptake and distribution of drug. In this review, we start by discussing the various models that have been used in this research area, highlighting the different types of information they can provide. We then go on to describe more recent methods that incorporate the impact of atherosclerotic lesions.

Clinical Characteristics and Prognosis of Peri-strut Low-intensity Area Detected by Optical Coherence Tomography

Background:

Peri-strut low-intensity area (PLIA) is a typical image pattern of neointima detected by optical coherence tomography (OCT) after stent implantation. However, few studies evaluated the predictors and prognosis of the PLIA; therefore, we aimed to explore the genesis and prognosis of PLIA detected by OCT in this study.

Methods:

Patients presenting neointimal hyperplasia documented by OCT reexamination after percutaneous coronary intervention were prospectively included from 2009 to 2011. Peri-strut intensity was analyzed and classified into two patterns: Low-intensity and high-intensity. Clinical characteristics were analyzed to assess their contribution to peri-strut intensity patterns. Follow-up were performed in patients who did not receive revascularization during OCT reexamination, and the prognosis of the patients was evaluated.

Results:

There were 128 patients underwent OCT reexamination after stent implantation included in the study. PLIA was detected in 22 (17.2%) patients. The incidence of PLIA was positively correlated with serum triglyceride (odds ratio [OR]: 2.11, 95% confidence interval [CI]: 1.14–3.90, P = 0.017), low-density lipoprotein (OR: 2.61, 95% CI: 1.22–5.66, P = 0.015), history of cerebrovascular disease (OR: 101.11, 95% CI: 6.54–1562.13, P < 0.001), and initial clinical presentation of acute coronary syndrome (ACS, OR: 18.77, 95% CI: 2.73–128.83, P = 0.003) while negatively correlated with stent implantation time (OR: 0.57, 95% CI: 0.33–0.98, P = 0.043). The median follow-up was longer than 3.8 years. Major adverse cardiovascular events (MACEs) occurred in 7 (7.3%) patients while showed no correlation with PLIA. A total of 17 (17.7%) patients experienced unstable angina (UA) and showed significant correlation with PLIA (hazard ratio: 6.16, 95% CI: 1.25–30.33, P = 0.025).

Conclusions:

PLIA detected by OCT was positively correlated with higher serum lipid level, history of cerebrovascular disease and initial presentation of ACS, and negatively correlated with stent implantation time. Patients with PLIA were more likely to have UA than those with high-intensity while no significant difference was found in MACEs.

Coronary evaginations and peri-scaffold aneurysms following implantation of bioresorbable scaffolds: incidence, outcome, and optical coherence tomography analysis of possible mechanisms

BACKGROUND

Peri-stent coronary evaginations may disturb flow and have been proposed as possible risk factor for late stent thrombosis. We describe incidence, predictors, and possible mechanisms of coronary evaginations 12 months after implantation of bioresorbable vascular scaffolds (BVS).

METHODS AND RESULTS

One hundred and two BVS implanted in 90 patients (age 63 ± 13 years, 71 males, 14 diabetics) were analysed with angiography and optical coherence tomography (OCT) 12 months after implantation. Evaginations were identified as any hollow in the luminal vessel contour between well-apposed struts and were classified as major when extending ≥3 mm with a depth ≥10% of the BVS diameter. Fifty-five (54%) of the BVS (50(56%) of the patients) had at least one evagination (6.1 ± 6.2 evaginations per BVS), with a mean volume of 1.9 ± 1.9 mm(3). Major evaginations were only found in one patient, and in-BVS aneurysms in three patients (4BVS). The presence of evaginations was strongly associated with that of malapposition (P = 0.003) and strut fractures (P = 0.01). No association could be shown between the presence and volume of the evaginations and any clinical variable or the presence of uncovered struts (P > 0.5). Peri-strut low-intensity areas (PSLIA) were present in 29 (53%) of the BVS with evaginations and 12 (26%) of those without (P = 0.0049); their presence was independently associated with the presence, the number (P < 0.003) and volume of the evaginations (P = 0.004) and with that of strut fracture.

CONCLUSIONS

Optical coherence tomography-detected evaginations are relatively common after BVS implantation, but, as for modern drug-eluting metallic stents, major evaginations are very rare. Optical coherence tomography evidence of immature neointima and strut fractures were associated with more severe development of evaginations.

OCT demonstrating neoatherosclerosis as part of the continuous process of coronary artery disease

Although the advent of drug-eluting stents has reduced the rates of target vessel revascularization, there are observations of ongoing stent failure occurring very late after stent implantation and presenting as very late restenosis or as very late stent thrombosis. The de novo development of atherosclerosis within the neointimal region, called neoatherosclerosis, has been identified as one of the pathomechanisms of these observed late stent failures. The mechanisms of neoatherosclerosis development and its association with stent failure are currently the subject of intensive research. Optical coherence tomography (OCT) is an invasive imaging modality that allows us to visualize the micromorphology of coronary arteries with near-histological resolution, thus providing detailed assessment of the morphological characteristics of the neointima after stent implantation, including neoatherosclerosis. Several OCT studies have tried to provide in vivo insights in the mechanisms of neoatherosclerosis development and its association with late stent failure. This review summarizes the current insights into neoatherosclerosis obtained with OCT and discusses the association of neoatherosclerosis with late stent failure.