Coupled benefits of nanotopography and titania surface chemistry in fostering endothelialization and reducing in-stent restenosis in coronary stents

Recent advances in coronary stents have all been distinctively focused towards directing re-endothelialization with minimal in-stent restenosis, potentially via alterations in surface topographical cues, for augmenting the efficacy of vascular implants. This perspective was proven by our group utilizing a simple and easily scalable nanosurface modification strategy on metallic stents devoid of any drugs or polymers. In the present work, we explore the impact of surface characteristics in modulating this cell response in-vitro and in-vivo, using titania coated cobalt-chromium (CC) stents, with and without nanotopography, in comparison to commercial controls. Interestingly, titania nanotopography facilitated a preferential cell response in-vitro as against the titania coated and bare CC surfaces, which can be attributed to surface topography, hydrophilicity, and roughness. This in turn altered the cellular adhesion, proliferation and focal contact formations of endothelial and smooth muscle cells. We also demonstrate that titania nanotexturing plays a pivotal role in fostering rapid re-endothelialization with minimal neointimal hyperplasia, leading to excellent in-vivo patency of CC stents post 8 weeks implantation in rabbit iliac arteries, in comparison to bare CC, nano-less titania coated CC, and commercial drug-eluting stents (CC DES), without administering antiplatelet agents. This exciting result for the drug and polymer-free titania nanotextured stents, in the absence of platelet therapy, reveals the possibility of proposing an alternative to clinical DES for coronary stenting.

A Randomized Comparison of the Healing Response Between the Firehawk Stent and the Xience Stent in Patients With ST-Segment Elevation Myocardial Infarction at 6 Months of Follow-Up (TARGET STEMI OCT China Trial): An Optical Coherence Tomography Study

Background

The healing response of the Firehawk stent in patients with ST-segment elevation myocardial infarction (STEMI) remains unclear.

Aim

We compared the vascular healing of a biodegradable polymer sirolimus-eluting stent (Firehawk) vs. a durable polymer everolimus-eluting stent (Xience) at 6 months after percutaneous coronary intervention (PCI) in patients with STEMI.

Methods

In this prospective, multicenter, randomized, non-inferiority study, patients within 12 h of STEMI onset were randomized in a ratio of 1:1 to receive Firehawk or Xience stents. Optical coherence tomography (OCT) follow-up was performed 6 months after the index procedure and assessed frame by frame. The primary endpoint was the neointimal thickness (NIT) at 6 months evaluated by OCT. The safety endpoint was target lesion failure (TLF) at 12 months.

Results

The Firehawk stent was non-inferior to the Xience stent in terms of the neointimal thickness (73.03 ± 33.30 μm vs. 78.96 ± 33.29 μm; absolute difference: −5.94 [one-sided 95% lower confidence bound: −23.09]; P_{non−inferiority} < 0.001). No significant difference was observed between the Firehawk and Xience groups regarding the percentage of uncovered struts (0.55 [0.08, 1.32]% vs. 0.40 [0.21, 1.19]%, P = 0.804), the percentage of malapposed struts (0.17 [0.00, 1.52]% vs. 0.17 [0.00, 0.69]%, P = 0.662), and the healing score (1.56 [0.23, 5.74] vs. 2.12 [0.91, 3.81], P = 0.647). At 12 months, one patient in the Firehawk group experienced a clinically indicated target lesion revascularization. No other TLF events occurred in both groups. Independent risk factors of the NIT included body mass index, hyperlipidemia, B2/C lesions, thrombus G3–G5, thrombus aspiration, and postdilation pressure.

Conclusion

In patients with STEMI, Firehawk was non-inferior to Xience in vascular healing at 6 months. Both stents exhibited nearly complete strut coverage, moderate neointimal formation, and minimal strut malapposition.

Clinical Trial Number

NCT04150016.

Can an ultrathin strut stent design and a polymer free, proendothelializing probucol matrix coating improve early strut healing? The FRIENDLY-OCT trial. An intra-patient randomized study with OCT, evaluating early strut coverage of a novel probucol coated polymer-free and ultra-thin strut sirolimus-eluting stent compared to a biodegradable polymer sirolimus-eluting stent

BACKGROUND

incomplete strut coverage determines the risk of stent thrombosis in the first months after stent implantation.

AIMS

To evaluate the potential better early healing of a novel probucol coated polymer free ultra-thin strut sirolimus eluting stent (PF-SES). [Clinical trial unique identifier: NCT02785237].

METHODS

Patients with two (angiographically similar) lesions with clinical indication for PCI were enrolled. The investigated stent was compared to a thin strut, bioresorbable polymer, sirolimus eluting stent (BP-SES). Every patient received both stents, one in each lesion, assigned in a randomized sequence. OCT was systematically performed at 3 months. Primary end point was the difference in the proportion of covered struts at 3 months (defined as ≥20 μm of tissue coverage). Secondary end points included differences in percentage of uncovered struts (0 μm coverage), mean strut coverage thickness, and malapposed struts' coverage proportion. Major adverse cardiac events (cardiac death, myocardial infarction, target lesion revascularization, and definite or probable stent thrombosis) at 12 months were also evaluated.

RESULTS

70 patients were included. At 3 months, a consistent and significantly higher strut coverage rate (≥20 μm) was observed in PF-SES as compared to BP-SES, both for well apposed (87.3% versus 79.1%, p < 0.001) and malapposed struts (50.4% vs 37.8%, p 0.00). Uncoverage rate (0 μm) was also significantly lower for the PF-SES (3.1% vs 5.3%, p < 0.001). There were no differences in clinical endpoints.

CONCLUSION

The probucol coated non-polymeric ultra-thin strut sirolimus eluting stent showed a significantly better early strut coverage at 3 months.

Surface engineering at the nanoscale: A way forward to improve coronary stent efficacy

Coronary in-stent restenosis and late stent thrombosis are the two major inadequacies of vascular stents that limit its long-term efficacy. Although restenosis has been successfully inhibited through the use of the current clinical drug-eluting stent which releases antiproliferative drugs, problems of late-stent thrombosis remain a concern due to polymer hypersensitivity and delayed re-endothelialization. Thus, the field of coronary stenting demands devices having enhanced compatibility and effectiveness to endothelial cells. Nanotechnology allows for efficient modulation of surface roughness, chemistry, feature size, and drug/biologics loading, to attain the desired biological response. Hence, surface topographical modification at the nanoscale is a plausible strategy to improve stent performance by utilizing novel design schemes that incorporate nanofeatures via the use of nanostructures, particles, or fibers, with or without the use of drugs/biologics. The main intent of this review is to deliberate on the impact of nanotechnology approaches for stent design and development and the recent advancements in this field on vascular stent performance.

Malapposed Struts with Cre8, Biomatrix, and Xience Stents Assessed with OCT Immediately after Implantation and at 6-Month Follow-Up: Can the Different Biomechanical Characteristics of the Three Stents Impact on Struts Malapposition?

Background. Although the clinical effects of stent malapposition remain controversial, several analyses of stent registries consistently have found that malapposed struts were frequently identified in patients who experienced stent thrombosis. In this study, which is a subanalysis of the previously published CREBX-OCT study, we compared optical coherence tomography (OCT) analysis at the index percutaneous coronary intervention (PCI) and at six-month follow-up in 37 patients randomly assigned to receive, by a single operator, three different second-generation drug-eluting stents (Cre8, Biomatrix, and Xience) aiming to clarify if the malapposition observed at six-month follow-up was persistent or late-acquired. Moreover, we investigated if there were some differences in the behavior of the three different kinds of stents in relation to the struts malapposition. Material and Methods. We analyzed 614 and 599 cross sections and 5514 and 5377 struts at the index PCI and at six-month follow-up, respectively. The qualitative analysis of the plaque composition among the three groups did not show significant differences. Results. The lumen area did not significantly change from the index procedure to the six-month follow-up in the three groups; on the contrary, the number of malapposed struts increased significantly in the Cre8 and Biomatrix groups but not in the Xience group: 0.58 ± 1.51 and 3.29 ± 5.33 ( $p<0.023$ ) in the Cre8 group, 0.55 ± 1.81 and 1.73 ± 2.28 ( $p<0.024$ ) in the Biomatrix group, and 0.55 ± 1.5 and 0.25 ± 0.87 ( $p<0.166$ ) in the Xience group, respectively. Conclusions. Therefore, the malapposition observed at six-month follow-up in our study population could be mainly considered as acquired and attributable to biomechanical reasons due to the structural differences among the three stents. This trial is registered with Clinical Trials.gov Identifier: NCT02850497.

Endpoint selection for noninferiority percutaneous coronary intervention trials: a methodological description

Background:

The objective of this review is to provide a practical update on endpoint selection for noninferiority (NI) studies in percutaneous coronary intervention studies.

Methods:

A PubMed search was conducted for predefined terms to explore the use of NI designs and intrapatient comparisons to determine their current importance. Sample size calculations for the most frequently used endpoints with NI hypotheses were done to increase statistical awareness.

Results:

Reported NI trials, with the most frequently chosen clinical endpoint of major adverse cardiac events (MACE), had NI margins ranging from 1.66% to 5.00%, resulting in patient populations of 400–1500 per treatment group. Clinical study endpoints comprising of MACE complemented with rates of bleeding complications and stent thrombosis (ST) are suggested to conduct a statistically and clinically meaningful NI trial. Study designs with surrogate endpoints amenable to intrapatient randomizations, are a very attractive option to reduce the number of necessary patients by about half. Comparative clinical endpoint studies with MACE and ST/bleeding rates to study a shortened dual antiplatelet therapy (DAPT) in coronary stent trials are feasible, whereas ST as the sole primary endpoint is not useful.

Conclusions:

Expanded composite clinical endpoints (MACE complemented by ST and bleeding rates and intrapatient randomization for selected surrogate endpoints) may be suitable tools to meet future needs in device approval, recertification and reimbursement.

One-year clinical results of the NANO registry: A multicenter, prospective all-comers registry study in patients receiving implantation of a polymer-free sirolimus-eluting stent

OBJECTIVES

We aimed to evaluate the safety and efficacy of Nano+™ (Lepu Medical, Beijing, China) stent implantation in all-comer patients at the 1-year follow-up.

BACKGROUND

The Nano+™ stent is a novel polymer-free sirolimus-eluting stent polymer that employs nanoporous stent surface technology to control drug-delivery. The Nano+™ stent is one of the most widely used drug-eluting stent (DES) in China.

METHODS

A total of 2,481 consecutive patients were included in the multicenter and prospective NANO registry. In this study, the primary endpoint was target lesion failure (TLF) at 1-year follow-up, defined as a composite of cardiac death, target vessel nonfatal myocardial infarction (TV-MI), and clinically driven target lesion revascularization (TLR). The safety endpoint was the occurrence of definite or probable stent thrombosis (ST).

RESULTS

Up to 40.2% of patients presented with acute myocardial infarction (AMI). A total of 63.9% of the 2,904 lesions were American College of Cardiology/American Heart Association (ACC/AHA) type B2 or C lesions. One-year follow-up data were available for 98.4% of patients. The 1-year rate of TLF was 3.1% with rates of 1.3, 1.8, and 0.4% for clinically driven TLR, cardiac death, and TV-MI, respectively. ST occurred in 0.4% of patients. Diabetes mellitus, AMI, left ventricular ejection fraction <40% and long lesions (>40 mm) were independent predictors of 1-year TLF.

CONCLUSIONS

The 1-year clinical outcomes were excellent for Nano+™ polymer-free SES implantation in an all-comer patient population. Follow-up will be extended up to 5 years, to further elucidate the potential long-term clinical benefits.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02929030.

Vulnerable struts with CRE8, Biomatrix and Xience stents assessed with OCT and their correlation with clinical variables at 6-month follow-up: the CREBX-OCT study

First-generation drug eluting stents (DES) reduced the incidence of restenosis and need for repeated target lesion revascularization but, in autoptic studies, frequently resulted in incomplete endothelial coverage, which is an important predictor of late adverse events and increased mortality after stent implantation. More recently, not only uncovered, but also malapposed or protruding struts have been considered vulnerable structures, as they are deemed to perturb blood flow, whereas only struts well embedded into the vessel wall are considered stable. We compared the number of uncovered and of other vulnerable (protruding or malapposed) struts among three different second-generation drug-eluting stents (DES) (Cre8, Biomatrix, Xience), using optical coherence tomography (OCT) 6 months after implantation. Moreover, we analyzed the relationship between the percentage of vulnerable struts and the clinical characteristics of patients. 60 patients with stable angina or non-ST-Elevation acute coronary syndrome and indication to percutaneous angioplasty were randomly assigned to receive one of the three DES. After 6 months, OCT images were obtained. After 6 months, OCT images were obtained (1289 cross sections; 10,728 struts). None of the three DES showed non-coated struts or areas of stent thrombosis. Significant differences in the average number of protruding struts (Cre8: 33.9 ± 12.6; Biomatrix: 26.2 ± 18.1; Xience: 13.2 ± 8.5; p < 0.001) and in the proportion of malapposed struts (Cre8: 0.7%; Biomatrix: 0.9%; Xience: 0.0%; p = 0.040) and of incomplete stent apposition area (Cre8: 10.4%; Biomatrix: 4.7%; Xience: 0.7%; p < 0.001) were observed. No significant difference was found in neointimal hyperplasia area with a not significant tendency toward greater minimal and maximal struts thickness for Biomatrix. In comparison with Cre8 and Biomatrix, Xience showed a significantly lower proportion of vulnerable struts in all clinical sub-groups considered. In the group of 60 patients a significant relation was found between age and number of vulnerable struts (p = 0.014). The three second-generation DES were similarly effective in permitting neo-intimal formation and complete struts coating 6 months after implantation, but Cre8 and Biomatrix showed a greater proportion of protruding and malapposed struts.Trail Registry: Clinical Trials.gov Identifier: NCT02850497.

Long-Term Performance of the COMBO Dual-Therapy Stent: Results from the REMEDEE Registry

BACKGROUND

Data of long-term safety and efficacy of the COMBO dual-therapy stent is lacking. REMEDEE Registry evaluated the COMBO stent and showed low clinical event rates up to 3 year. We report the clinical outcomes at 4-year follow-up of this registry.

METHODS

The REMEDEE Registry is a prospective, multicenter registry with minimal exclusion criteria, evaluating clinical outcomes after treatment with the COMBO stent. A 1000 patients were enrolled between June 2013 and March 2014. Target lesion failure (TLF), defined as a composite of cardiac death, target-vessel myocardial infarction (TV-MI) and target lesion revascularization (TLR), at 4-year follow-up was the primary focus of this analysis.

RESULTS

Four-year follow-up data were obtained in 97.3% of patients. TLF was present in 117 patients (11.9%). Cardiac death occurred in 45 patients (4.6%), TV-MI was observed in 25 patients (2.6%) and TLR was performed in 73 patients (7.5%). Of the 7.5% TLR at 4 years, 1.5% were beyond 2 years. Definite ST was seen in 7 patients (0.7%) and probable ST in 1 (0.1%). No definite or probable ST occurred between 3 and 4 years follow-up. At 4-year follow-up, 93.1% of patients were free of ischemic symptoms.

CONCLUSION

This registry showed excellent 4-year results after COMBO stent placement, with no ST beyond 3 years.

Serial Optical Coherence Tomography at Baseline, 7 Days, and 1, 3, 6 and 12 Months After Bioresorbable Scaffold Implantation in a Growing Porcine Model

BACKGROUND

Little is known about serial changes in lumen and device dimensions after bioresorbable scaffold implantation in a growing animal model. Methods and Results: ABSORB (n=14) or bare metal stents (ICROS amg [Abbott Vascular, Santa Clara, CA, USA], Winsen-Luhe, Germany; n=15) were implanted in the coronary arteries of domestic swine (a hybrid of Finnish-Norwegian Landrace swine) weighing 30-35 kg. Angiography and optical coherence tomography (OCT) were performed immediately after implantation and repeated at 7 days, 1, 3, 6 and 12 months after the index procedure. One month after implantation, mean lumen area decreased relative to baseline in both groups (relative area change from baseline, -41.4±15.6% for ABSORB vs. -20.9±18.6% for ICROS) while mean device area decreased only in the ABSORB group (relative area change: -11.1±9.4% vs. +0.14±7.95%, respectively). At 12 months, mean lumen area increased relative to baseline in both groups (relative area change from baseline, +55.6±22.4% vs. +32.3±83.6%, respectively) in accordance with the swine growth weighing up to 260-300 kg. Mean device area in the ICROS group remained stable whereas that in the ABSORB group began to increase between 3 and 6 months along with the vessel growth (relative area change: +107.8±25.7% vs. +0.14±7.95%).

CONCLUSIONS

In the growing porcine model, ABSORB was associated with greater extent of recoil 1 month after implantation compared with ICROS but demonstrated substantial adaptability to vessel growth in late phase.

A serial 3- and 9-year optical coherence tomography assessment of vascular healing response to sirolimus- and paclitaxel-eluting stents

Early-generation drug-eluting stents (DES) have been demonstrated to delay vascular healing. Limited optical coherence tomography (OCT) data on the very long-term neointimal response after DES implantation are available. The aim of this study was a serial OCT assessment of neointimal thickness, stent strut coverage, malapposition, and protrusion as markers of neointimal response at 3 and 9 years after implantation of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES). In this single-centre, longitudinal study consecutive patients undergoing elective PCI with SES or PES were included. OCT analysis was performed after 3 and 9 years by the independent core laboratory. A total of 22 subjects (8 SES and 14 PES) underwent an OCT assessment at 3 and 9 years post index procedure. The lumen, neointimal and malapposition area and the neointimal thickness (SES ∆50 µm, p = 0.195, PES ∆10 µm, p = 0.951) did not change significantly over the 6 year follow-up. No differences in the incidence of uncovered, malapposed or protruding struts were found in each type of stent. At 3 and 9 years after PCI, implantation of early-generation SES and PES may be associated with similar neointimal thickness, strut coverage, malapposition and protrusion, as assessed by serial OCT examination among patients with uneventful follow-up at 3 years post procedure. The small size of the study warrants judicious interpretation of our results and confirmation in larger multimodality imaging studies, including patients treated with contemporary stent platforms.

Three-months optical coherence tomography analysis of a biodegradable polymer, sirolimus-eluting stent

OBJECTIVE

We aimed to assess early neointimal healing by optical coherence tomography (OCT) 3 months after implantation of the ultrathin Orsiro® sirolimus-eluting stent with biodegradable polymer.

BACKGROUND

New generations of drug-eluting stents with biodegradable polymer have been developed to avoid the continued vascular irritation of durable polymers.

METHODS

In this prospective, open-label study, 34 patients received an Orsiro® sirolimus-eluting stent with biodegradable polymer. In a subgroup of patients (n = 15), the intervention was performed under OCT guidance. All patients underwent OCT-examination at three months. The primary endpoint was 3-month neointimal healing (NIH) score, calculated by weighing the presence of filling defects, malapposed and uncovered struts. Secondary endpoint was maturity of tissue coverage at 3 months.

RESULTS

At 3 months, NIH score was 13.7 (5.4-22), covered struts per lesion were 90% (84-97%), malapposed struts were 2.7% (0.8-5.4%) and rate of mature tissue coverage was 47% (42-53%). No target lesion failure occurred up to 12 months. Patients with OCT-guided stent implantation demonstrated a trend toward earlier stent healing as demonstrated by superior NIH scores (angio guided: 17.6% [8.8-26.4]; OCT-guided: 9.8% [4.0-15.5]; mean difference -8, [95%CI: -18.7-2.9], P = 0.123). This group had significantly more covered struts per lesion (angio-guided: 86% [82-90]; 95% [92-99]; mean difference 9% [95%CI: 3-15], P = 0.001).

CONCLUSION

The Orsiro® sirolimus-eluting stent with biodegradable polymer shows early vascular healing with a high rate of strut coverage at 3-month follow-up. OCT guided stent implantation had a positive impact on early vascular healing.

Healing score of the Xinsorb scaffold in the treatment of de novo lesions: 6-month imaging outcomes

The objectives of this study are to assess the healing score (HS) and neointimal thickness of the Xinsorb scaffold, and explore the relationships between the implanted patterns, neointimal thickness, and HS. The Xinsorb bioresorbable sirolimus-eluting scaffold is the first domestically designed and fabricated bioresorbable scaffold in China. The 6-month follow-up found it to be safe and effective in the treatment of single de novo coronary lesions. The Xinsorb scaffolds were implanted in 30 patients with symptomatic ischemic coronary disease. A 6-month follow-up was performed in a subset of 19 patients; the HS and neointimal thickness were evaluated by optical coherence tomography. Struts were classified as ApposedCovered, ApposedUncovered, MalapposedCovered, MalapposedUncovered, jailing and presence of intraluminal masses. The implanted pressure, implanted duration, and post-expansion pressure were recorded during the operation. We evaluated the relationship between the HS or neointimal thickness and the implanted pressure, holding time, and post-expansion pressure. The device and procedure success rates were both 100%. No major adverse cardiac or scaffold-thrombus related events occurred. At 6 months, 12,295 struts were analyzed to determine the HS (6.23) and neointimal thickness (0.1021 ± 0.05718 mm) in the Xinsorb scaffolds. There was a strong negative relationship between the HS and the implantation duration (Pearson r = - 0.518, p = 0.023). A significant negative relationship also existed between the HS and post-dilatation (Pearson r = - 0.631, p = 0.004). The Xinsorb scaffold HS appears negative correlated with the implanted duration and post-dilatation. We will further evaluate the HS of randomized controlled trial of the Xissorb scaffold.