ABSORB biodegradable stents versus second-generation metal stents: a comparison study of 100 complex lesions treated under OCT guidance

Percutaneous delivery and degradation of a shape memory elastomer poly(glycerol dodecanedioate) in porcine pulmonary arteries

Shape memory biodegradable elastomers are an emergent class of biomaterials well-suited for percutaneous cardiovascular repair requiring nonlinear elastic materials with facile handling. We have previously developed a chemically crosslinked shape memory elastomer, poly (glycerol dodecanedioate) (PGD), exhibiting tunable transition temperatures around body temperature (34-38 °C), exhibiting nonlinear elastic properties approximating cardiac tissues, and favorable degradation rates in vitro. Degree of tissue coverage, degradation and consequent changes in polymer thermomechanical properties, and inflammatory response in preclinical animal models are unknown material attributes required for translating this material into cardiovascular devices. This study investigates changes in the polymer structure, tissue coverage, endothelialization, and inflammation of percutaneously implanted PGD patches (20 mm × 9 mm x 0.5 mm) into the branch pulmonary arteries of Yorkshire pigs for three months. After three months in vivo, 5/8 samples exhibited (100%) tissue coverage, 2/8 samples exhibited 85-95% tissue coverage, and 1/8 samples exhibited limited (<20%) tissue coverage with mild-moderate inflammation. PGD explants showed a (60-70%) volume loss and (25-30%) mass loss, and a reduction in polymer crosslinks. Lumenal and mural surfaces and the cross-section of the explant demonstrated evidence of degradation. This study validates PGD as an appropriate cardiovascular engineering material due to its propensity for rapid tissue coverage and uneventful inflammatory response in a preclinical animal model, establishing a precedent for consideration in cardiovascular repair applications.

Effects of aggressive predilatation, sizing, and postdilatation strategy for coronary bioresorbable vascular scaffolds implantation

BACKGROUND

The results of the recent Amsterdam Investigator-Initiated Absorb Strategy All-Comers trial showed that the predilatation, sizing, and postdilatation (PSP) technique did not lower the long-term rates of scaffold thrombosis and adverse events. We evaluated the impact of aggressive PSP bioresorbable vascular scaffold (BRS) implantation on the short- and long-term clinical outcomes.

METHODS

From June 2014 to December 2016, 150 patients with BRS implantation were enrolled and received successful percutaneous coronary intervention (PCI), of whom 104 received aggressive PSP technique (high-pressure predilatation and lesion preparation in addition to the traditional PSP technique). Short- and long-term outcomes were compared.

RESULTS

All patients underwent successful PCI and BRS implantation with final Thrombolysis in Myocardial Infarction grade 3 flow. The baseline and procedure characteristics were similar in both groups. Debulking techniques were used in 13 (8.7%) patients. Intracoronary imaging modalities were used in 73 (48.7%) patients. After BRS implantation, no adverse events were observed within 30 days in both groups. During the mean follow-up period of 2.98 ± 0.77 years, 12 (8.0%) patients experienced major adverse cardiovascular events (MACEs), including one cardiovascular death (0.6%), three nonfatal myocardial infarction (2.0 %), and 11 target-vessel revascularization (7.3 %). Multivariate Cox regression analysis showed that aggressive PSP remained an independent protective factor for MACEs. Moreover, the use of intracoronary imaging and rotablation atherectomy was associated with better clinical outcomes.

CONCLUSION

Lesion preparation by aggressive PSP in BRS implantation was associated with better long-term clinical outcomes.

Clinical presentation does not affect acute mechanical performance of the Novolimus-eluting bioresorbable vascular scaffold as assessed by optical coherence tomography

Introduction

Initial trials of bioresorbable vascular scaffolds (BVS) have mostly excluded patients presenting with acute coronary syndrome (ACS). However, these patients might benefit from a BVS platform, in particular as they are often younger and have been less frequently treated than patients with chronic disease.

Aim

To compare the acute performance of a Novolimus eluting BVS in ACS and non-ACS patients using optical coherence tomography (OCT) in patients presenting with acute or chronic coronary syndrome.

Material and methods

The final OCT pullback of 79 patients (34 with ACS, 45 non-ACS) was analysed at 1-mm intervals. The following indices were calculated: mean and minimal area, residual area stenosis, incomplete strut apposition, tissue prolapse, eccentricity index, symmetry index, strut fracture, and edge dissection.

Results

OCT showed a minimum lumen area (non-ACS vs. ACS) of 6.2 ±2.1 vs. 5.6 ±1.5 mm² (p = 0.21). Mean residual area stenosis was 14.5% vs. 19.5% (p = 0.39). The mean eccentricity index did not differ significantly (0.78 ±0.13 vs. 0.78 ±0.06; p = 0.42). There was a non-significant tendency for more fractures in the non-ACS group (22.2% vs. 5.9%; p = 0.07). Prolapse area was comparable (4.4 ±7.4 mm² vs. 5.2 ±10.9 mm²; p = 0.62).

Conclusions

This is the first study to investigate the acute mechanical performance of a Novolimus-eluting BVS in patients with different clinical presentations using OCT. We found that clinical presentation did not determine acute mechanical performance as assessed by the final OCT pullback. There was evidence of more mechanical complications in terms of fractures and a higher percentage of incomplete strut apposition in the group of patients with chronic coronary syndrome.

The impact of plaque type on strut embedment/protrusion and shear stress distribution in bioresorbable scaffold

AIMS

Scaffold design and plaque characteristics influence implantation outcomes and local flow dynamics in treated coronary segments. Our aim is to assess the impact of strut embedment/protrusion of bioresorbable scaffold on local shear stress distribution in different atherosclerotic plaque types.

METHODS AND RESULTS

Fifteen Absorb everolimus-eluting Bioresorbable Vascular Scaffolds were implanted in human epicardial coronary arteries. Optical coherence tomography (OCT) was performed post-scaffold implantation and strut embedment/protrusion were analysed using a dedicated software. OCT data were fused with angiography to reconstruct 3D coronary anatomy. Blood flow simulation was performed and wall shear stress (WSS) was estimated in each scaffolded surface and the relationship between strut embedment/protrusion and WSS was evaluated. There were 9083 struts analysed. Ninety-seven percent of the struts (n = 8840) were well-apposed and 243 (3%) were malapposed. At cross-section level (n = 1289), strut embedment was significantly increased in fibroatheromatous plaques (76 ± 48 µm) and decreased in fibrocalcific plaques (35 ± 52 µm). Compatible with strut embedment, WSS was significantly higher in lipid-rich fibroatheromatous plaques (1.50 ± 0.81 Pa), whereas significantly decreased in fibrocalcified plaques (1.05 ± 0.91 Pa). After categorization of WSS as low (<1.0 Pa) and normal/high WSS (≥1.0 Pa), the percent of low WSS in the plaque subgroups were 30.1%, 31.1%, 25.4%, and 36.2% for non-diseased vessel wall, fibrous plaque, fibroatheromatous plaque, and fibrocalcific plaque, respectively (P-overall < 0.001).

CONCLUSION

The composition of the underlying plaque influences strut embedment which seems to have effect on WSS. The struts deeply embedded in lipid-rich fibroatheromas plaques resulted in higher WSS compared with the other plaque types.

The role of optical coherence tomography guidance in scaffold versus stent optimization

BACKGROUND

Optical coherence tomography showed a great ability to identify adverse features during percutaneous coronary intervention with drug-eluting stents and resulted in better clinical outcomes. The study aimed to assess the impact of optical coherence tomography on intraoperative decision-making during implantation of Absorb bioresorbable scaffolds versus everolimus drug-eluting stents.

RESULTS

We performed an observational study that included 223 consecutive patients post optical coherence tomography-guided implantation of either Absorb bioresorbable scaffolds (162 patients) or everolimus drug-eluting stents (61 patients). We studied the influence of optical coherence tomography on intraoperative decision-making during implantation of bioresorbable scaffolds versus drug-eluting stents by analyzing the total rate of optical coherence tomography-dependent modifications in each device. After satisfactory angiographic results, the total rate of required intervention for optical coherence tomography detected complications was significantly higher in the bioresorbable scaffolds arm compared to drug-eluting stents arm (47.8% versus 32.9%, respectively; p = 0.019). The additional modifications encompassed further optimization in the case of device underexpansion or struts malapposition, and even stenting in the case of strut fractures, or significant edge dissection.

CONCLUSIONS

Compared to drug-eluting stents, Absord scaffold was associated with a significantly higher rate of optical coherence tomography-identified intraprocedural complications necessitating further modifications. The study provides some hints on the reasons of scaffolds failure in current PCI practice; it offers a new insight for the enhancement of BRS safety and presents and adds to the growing literature for successful BRS utilization.

Clinical considerations and recommendations for OCT-guided carotid artery stenting

Introduction: Optical Coherence Tomography (OCT) is an intravascular imaging providing high-resolution images of morphological features of arterial wall. Nowadays, OCT is an accepted intravascular modality to study coronary arteries, stent implantation, and vessel injury. In the last decade, an increasing interest have been focused on the application of OCT in carotid arteries.Areas covered: Literature evidence in the application of OCT in carotid arteries still remains debated. So far, OCT has been used as a research tool, aiming to evaluate atherosclerotic plaques' features and stents' behavior after implantation. This paper is intended to summarize clinical evidences and practices in the use of OCT in carotid arteries district and during CAS procedures. Literature review was completed via Pubmed search using Keywords.Expert opinion: CAS is a safe and effective procedure when performed by trained physicians with a tailored approach. In this scenario, ambiguous pictures at ultrasound, angiography, and IVUS might be clarified using OCT.By providing unprecedented microstructural information on atherosclerotic plaques, OCT may identify the features of vulnerable carotid plaque and, by identifying possible defects after stent implantation as malapposition and plaque prolapse, it may help the tailoring approach to CAS.

Optical Coherence Tomography for Coronary Bioresorbable Vascular Scaffold Implantation: A Randomized Controlled Trial

BACKGROUND

We investigated whether optical coherence tomography (OCT) guidance would reduce nonoptimal bioresorbable vascular scaffold (BVS) deployment.

METHODS

This was a randomized controlled trial. Patients who required percutaneous coronary intervention for ischemic heart disease were recruited from 2 centers in Korea. The enrolled patients were randomly assigned to receive either OCT-guided BVS (Absorb; Abbott Vascular) implantation or angiography-guided BVS implantation using an optimized technique. The primary outcome was nonoptimal deployment, which was a composite outcome of the following parameters assessed by OCT: a minimal scaffold area <5 mm², residual area stenosis >20%, incomplete apposition of the scaffold struts >5%, major edge dissection, or scaffold disruption. The secondary outcome was a procedural complication defined by the occurrence of no reflow, coronary perforation, or flow-limiting dissection.

RESULTS

Between September 2016 and January 2018, 88 patients (90 lesions) were assigned to OCT guidance, while 88 patients (89 lesions) were assigned to angiography guidance. The recruitment was prematurely terminated in March 2018 because the manufacturer stopped supplying BVS. Postprocedural OCT data were available for 88 lesions with OCT guidance and for 88 lesions with angiography guidance. There was nonoptimal BVS deployment postprocedurally in 35.2% of patients in the OCT-guidance group and in 38.6% in the angiography-guidance group (absolute difference, -3.7% [95% CI, -19.0% to 11.6%]; P=0.64). There were no procedural complications in either group.

CONCLUSIONS

OCT-guided BVS implantation did not reduce the incidence of nonoptimal deployment compared to that of angiography-guided BVS implantation (using optimized techniques).

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02894697.

Bioresorbable Vascular Scaffolds-Dead End or Still a Rough Diamond?

Percutaneous coronary interventions with stent-based restorations of vessel patency have become the gold standard in the treatment of acute coronary states. Bioresorbable vascular scaffolds (BVS) have been designed to combine the efficiency of drug-eluting stents (DES) at the time of implantation and the advantages of a lack of foreign body afterwards. Complete resolution of the scaffold was intended to enable the restoration of vasomotor function and reduce the risk of device thrombosis. While early reports demonstrated superiority of BVS over DES, larger-scale application and longer observation exposed major concerns about their use, including lower radial strength and higher risk of thrombosis resulting in higher rate of major adverse cardiac events. Further focus on procedural details and research on the second generation of BVS with novel properties did not allow to unequivocally challenge position of DES. Nevertheless, BVS still have a chance to present superiority in distinctive indications. This review presents an outlook on the available first and second generation BVS and a summary of results of clinical trials on their use. It discusses explanations for unfavorable outcomes, proposed enhancement techniques and a potential niche for the use of BVS.

Impact of lesion angle on optical coherence tomography findings and clinical outcomes after drug-eluting stent implantation in curved vessels

Tortuous coronary lesions are associated with adverse outcomes after implantation of bare metal or first-generation drug-eluting stents (DESs). We investigated the impact of lesion angle on vessel wall injuries and stent apposition as assessed by optical coherence tomography (OCT) after second- and newer-generation DES implantation. We investigated 95 de novo lesions treated with a single DES (62 platinum-chromium everolimus-eluting stents and 33 bioresorbable-polymer sirolimus-eluting stents). Post-intervention OCT findings were compared between angled lesions (≥ 45°; n = 33) and non-angled lesions (< 45°; n = 62). The 12-month clinical outcomes were also compared between the groups. Cross-sectional OCT analysis revealed that compared to non-angled lesions, angled ones had a significantly higher incidence of intra-stent dissection around the centre of the angle (19.7% vs. 10.8%, p = 0.01) and incomplete stent apposition (ISA) in the distal and proximal sub-segments (10.0% vs. 4.1%, p = 0.002; 15.3% vs. 7.9%, p < 0.001, respectively). Strut-based analysis also showed that angled lesions demonstrated a higher rate of malapposed strut in the distal and proximal sub-segments (3.0% vs. 0.9%, p < 0.001; 4.3% vs. 1.8%, p < 0.001, respectively). The 12 month clinical outcomes were comparable between the groups. Compared to non-angled lesions, angled coronary lesions were associated with a higher incidence of intra-stent dissection and ISA on post-intervention OCT after implantation of second- and newer-generation DESs.

Procedural findings and early healing response after implantation of a self-apposing bioresorbable scaffold in coronary bifurcation lesions

We aimed to evaluate feasibility, early healing and self-correcting properties of the Desolve 150 bioresorbable scaffold (BRS) implanted in bifurcation lesions, using the simple, provisional side branch (SB) stenting technique. BIFSORB pilot was a proof-of-concept study enrolling 10 patients with stable angina pectoris and a bifurcation lesion with SB ≥ 2.5 mm and less than 50% diameter stenosis. Procedure and 1-month outcome was evaluated by optical coherence tomography (OCT) to assess scaffold performance and healing patterns. Nine patients were treated with Desolve 150 BRS and one delivery to the target bifurcation failed. Thrombus formation in the jailed SB ostium was seen in three cases, but was completely resolved at 1-month. OCT confirmed acute self-correcting properties. No clinical events were reported after six months. Scaffold diameter by OCT increased in the proximal main vessel from 3.09 ± 0.16 mm to 3.34 ± 0.18 mm (p = 0.01) and in distal main vessel from 2.82 ± 0.26 mm to 3.02 ± 0.29 mm (p < 0.01) at one-month follow-up. SB ostial diameter stenosis improved from 42 ± 15% to 34 ± 12% (p = 0.01). Malapposition was effectively reduced after 1 month from 4.1 (1.4; 6.1)% to 0.1 (0; 0.6)% (p = 0.002). Treatment of bifurcation lesions using Desolve 150 BRS was feasible except for a delivery failure and unsettling thrombus formation behind jailing SB struts, which was completely resolved at 1-month. Self-correcting and even self-expanding properties were confirmed.

Bioresorbable Scaffold for Treatment of Coronary Artery Lesions: Intravascular Ultrasound Results From the ABSORB Japan Trial

OBJECTIVES

The aim of this study was to characterize post-procedural intravascular ultrasound (IVUS) findings in the ABSORB Japan trial, specifically stratified by the size of target coronary arteries.

BACKGROUND

Despite overall noninferiority confirmed in recent randomized trials comparing bioresorbable vascular scaffolds (BVS) (Absorb BVS) and cobalt-chromium everolimus-eluting metallic stents (CoCr-EES), higher event rates of Absorb BVS have been reported with suboptimal deployment, especially in small coronary arteries.

METHODS

In the ABSORB Japan trial, 150 patients (2:1 randomization) were scheduled in the IVUS cohort. Small vessel was defined as mean reference lumen diameter <2.75 mm. Tapered-vessel lesions were defined as tapering index (proximal/distal reference lumen diameter) ≥1.2.

RESULTS

Overall, IVUS revealed that the Absorb BVS arm had smaller device expansion than the CoCr-EES arm did, which was particularly prominent in small- and tapered-vessel lesions. Higher tapering index was also associated with higher rates of incomplete strut apposition in Absorb BVS, but not in CoCr-EES. With respect to procedural techniques, small-vessel lesions were treated more frequently with noncompliant balloons at post-dilatation but using significantly lower pressure in the Absorb BVS arm. In contrast, tapered-vessel lesions were post-dilated at equivalent pressure but with significantly smaller balloon catheters in the Absorb BVS arm, compared with the CoCr-EES arm.

CONCLUSIONS

The significantly smaller device expansion especially in small vessels may account for the poorer outcomes of Absorb BVS in this lesion type. Appropriate optimization strategy, possibly different between polymeric and metallic devices, needs to be established for bioresorbable scaffold technology. (AVJ-301 Clinical Trial: A Clinical Evaluation of AVJ-301 Absorb™ BVS) in Japanese Population [ABSORB JAPAN]; NCT01844284).

In vitro mechanical behavior and in vivo healing response of a novel thin-strut ultrahigh molecular weight poly-l-lactic acid sirolimus-eluting bioresorbable coronary scaffold in normal swine

BACKGROUND

New generation bioresorbable scaffolds (BRS) promise to improve the outcomes of current generation BRS technologies by decreasing wall thickness while maintaining structural strength. This study aimed to compare the biomechanical behavior and vascular healing profile of a novel thin-walled (98 μm) sirolimus-eluting ultrahigh molecular weight BRS (Magnitude, Amaranth Medical) to the Absorb everolimus-eluting bioresorbable vascular scaffold (Abbott Vascular).

METHODS AND RESULTS

In vitro biomechanical testing showed lower number of fractures on accelerated cycle testing over time (at 21K cycles = 20.0 [19.0-21.0] in Absorb versus 0.0 [0.0-1.0] in Magnitude-BRS). Either Magnitude (n = 43) or Absorb (n = 22) was implanted in 65 coronary segments of 22 swine. Scaffold strut's coverage was evaluated using serial optical coherence tomography (OCT) analysis. At 14 days, Magnitude-BRS demonstrated a higher percentage of embedded struts (97.7% [95.3, 100.0] compared to Absorb (57.2% [48.0, 76.0], p = 0.003) and lower percentage of uncovered struts (0.0% [0.0, 0.0] versus Absorb 5.5% [2.6, 7.7], p = 0.02). Also, it showed a lower percent late recoil (-1.02% [-4.11, 3.21] versus 4.42% [-1.10, 8.74], p = 0.04) at 28 days. Histopathology revealed comparable neointimal proliferation and vascular healing responses between two devices up to 180 days.

CONCLUSION

A new generation thin walled (98-μm) Magnitude-BRS displayed a promising biomechanical behavior and strut healing profile compared to Absorb at the experimental level. This new generation BRS platform has the potential to improve the clinical outcomes shown by the current generation BRS.

OCT-guided Percutaneous Coronary Intervention in Bifurcation Lesions

Coronary artery bifurcation lesions remain challenging despite significant advancements in stent technology and development of specific bifurcation stenting approaches. Optical coherence tomography (OCT) is the intracoronary imaging technique with the highest resolution and can generate automatically contoured lumen areas across the variable geometry of bifurcation lesions. Knowledge of plaque severity and composition facilitates planning of the best strategy for percutaneous coronary intervention (PCI) and stenting. In particular, the provisional stent strategy preferred in this context can be modified when there is high risk of side-branch compromise at the ostium after main vessel stenting. OCT is unique because it allows the identification of the site of guide wire crossing, an important determinant of the final result. OCT can also be used to assess the procedural success of new dedicated bifurcation stent technologies and for the evaluation at follow-up of potential predictors of stent thrombosis, including stent malapposition, stent under-expansion and stent-edge dissection. Finally, the development of 3D OCT allows a better evaluation of coronary anatomy — particularly of side branch ostium that is difficult to visualise by 2D OCT — further improving the value of this technique in guiding PCI in these patients.

Long-term follow-up of BVS from a prospective multicenter registry: Impact of a dedicated implantation technique on clinical outcomes

OBJECTIVES

The aim of this study was to evaluate the impact of a consistent and dedicated implantation strategy on long-term outcomes after implantation of bioresorbable vascular scaffold (BVS) in a real-world cohort of patients with a high prevalence of complex lesions.

BACKGROUND

Bioresorbable vascular scaffolds may result in a reduced incidence of late and very-late scaffold thrombosis (ScT) after the complete reabsorption of the scaffold, but this hypothesis is hampered by data from RCTs that showed a higher than expected incidence of late events. However, these studies did not adopt a dedicated implantation technique, that proved to be fundamental in reducing the incidence of adverse events.

METHODS

573 consecutive patients (912 lesions) treated with bioresorbable scaffolds between May 2012 and December 2014 were enrolled in 3 high-volume centers that used a dedicated implantation strategy from the beginning. Primary endpoints were target-lesion failure (TLF) and definite and probable ScT. Secondary endpoints included myocardial infarction, target-lesion and target-vessel revascularization.

RESULTS

The registry enrolled a high complexity subset of lesions (69.4% of type B2 or C lesions; 10.3% of severe calcific lesions; 26.1% of bifurcations). Predilatation was performed in almost all cases (99.2%); intracoronary imaging was liberally adopted (37.3%). Mean scaffold length was 42.9 ± 27.4 mm per patient, and post-dilation with a 1:1 high-pressure (22 ± 3.5 atm) balloon was performed in 99.9% of lesions. Median follow-up (available for 98.6% of patients) was 981 days (IQR 802-1133). Overall incidence of ScT was reassuringly low: three thrombotic events occurred during the first year (0.5%), while only one event ensued in the second year of follow-up, and ScT rate remained stable thereafter up to the fourth year (0.7%). Cumulative TLF rates at 1, 2, 3 and 4 years were 3.0%, 6.0%, 7.8% and 12.2%.

CONCLUSIONS

These long-term results from a complex "real-world" population appear to be reassuring as regards to the incidence of ScT and TLF when BVS are implanted by experienced operators with a dedicated implantation technique.

Comparison of the Absorb bioresorbable vascular scaffold to the Xience durable polymer everolimus-eluting metallic stent in routine clinical practice: a propensity score-matched analysis from a multicenter registry

INTRODUCTION

Most clinical trials related to bioresorbable vascular scaffold (BVS) technology are limited to a highly selected patient population.

AIM

To evaluate early and long-term clinical outcomes of the Absorb everolimus-eluting BVS compared to the everolimus-eluting metallic XIENCE V stent in routine clinical practice.

MATERIAL AND METHODS

This is a multicenter, retrospective propensity score-matched comparative study, comprising 76 patients treated with a bare metal stents (BMS) and 501 with a XIENCE stent. Patients included in the study had stable and unstable angina and both types of myocardial infarction (STEMI and NSTEMI) as an indication for intervention and at least one significant de novo lesion in native coronary arteries. The primary endpoint was major adverse cardiovascular event (MACE), defined as death, myocardial infarction (MI), or target vessel revascularization (TVR).

RESULTS

Median follow-up was 400 days in both groups. After propensity score matching for patient baseline characteristics, only higher rate of predilatation, predominantly treated left anterior descending artery (LAD) and lower number of used stents in the BVS group remained statistically significant. After adjustment there was no difference in type of treated lesions. The MACE rate did not differ between BVS and drug-eluting stents (DES) groups (7.2% vs. 11.15%, respectively; p = 0.17). The TVR was 2.9% in both groups. Except in the periprocedural period, there were no deaths or MI in the BVS group. There was no stent thrombosis in either studied group.

CONCLUSIONS

In routine clinical practice throughout long-term follow-up, clinical outcomes of patients who successfully received the Absorb BVS did not differ from those of patients who received the Xience stent. Longer follow-up data are required to determine whether these findings will persist beyond one year.

Invasive assessment of coronary artery disease

Coronary artery disease is associated to high mortality and morbidity rates and an accurate diagnostic assessment during heart catheterization has a fundamental role in prognostic stratification and treatment choices. Coronary angiography has been integrated by intravascular imaging modalities, namely intravascular ultrasound and optical coherence tomography, which allow the precise quantification of the atherosclerotic burden of coronary arteries. The hemodynamic relevance of a given coronary stenosis can be assessed using stress or resting indexes: fractional flow reserve and instantaneous wave-free ratio are both coronary flow surrogates, used to guide percutaneous coronary interventions. This review summarizes the current state-of-the-art of invasive diagnostic methods during heart catheterization and highlights the potential role that an integration of anatomical and functional information enables.

Endoscopic biodegradable stents as a rescue treatment in the management of post bariatric surgery leaks: a case series

BACKGROUND AND AIMS

 Postoperative leak is one of the most feared complications after bariatric surgery. Endoscopic stenting is used to manage leaks by decreasing the gastrointestinal intraluminal pressure. The main advantage of endoscopic management is providing healing while still allowing for oral nutrition. However, limited literature exists on whether biodegradable stents can be used to control leaks when conventional metallic stents fail.

METHODS

 Our series consists of four patients who were found to have a leak as a complication of bariatric surgery. Two patients were initially managed by abdominal/chest drainage, and one required total parenteral nutrition. Conventional endoscopic exclusion techniques with short and long fully covered metallic stents were tried and failed in three of the four patients included in this series. Thus, biodegradable stents were used as a rescue option.

RESULTS

 Biodegradable stents provided immediate improvement for all of the patients, and Gastrografin studies were leak-free 2 days after the procedure. All patients were started on oral feeding and discharged home within 5 - 6 days later. Minimum outpatient follow-up of 8 weeks was achieved with no issues. Follow-up endoscopy was performed 2 - 3 months later in three patients and showed completely resorbed stents. The only drawback was the mucosal reaction to the stent causing dysphagia in two patients, who eventually needed esophageal dilatation.

CONCLUSION

 Biodegradable stents have the potential to provide a reasonable rescue option to manage post bariatric surgery leaks in patients who fail conventional endoscopic exclusion methods. However, data from larger studies are needed to collect information on which theoretical advantages/disadvantages of degradable biomaterials apply to real practice.

Late thrombotic events after bioresorbable scaffold implantation: a systematic review and meta-analysis of randomized clinical trials

Aims

To compare the long-term safety and efficacy of bioresorbable vascular scaffold (BVS) with everolimus-eluting stent (EES) after percutaneous coronary interventions.

Methods and results

A systematic review and meta-analysis of randomized clinical trials comparing clinical outcomes of patients treated with BVS and EES with at least 24 months follow-up was performed. Adjusted random-effect model by the Knapp-Hartung method was used to compute odds ratios (OR) and 95% confidence intervals (CI). The primary safety outcome of interest was the risk of definite/probable device thrombosis (DT). The primary efficacy outcome of interest was the risk of target lesion failure (TLF). Five randomized clinical trials (n = 1730) were included. Patients treated with Absorb BVS had a higher risk of definite/probable DT compared with patients treated with EES (OR 2.93, 95%CI 1.37-6.26, P = 0.01). Very late DT (VLDT) occurred in 13 patients [12/996 (1.4%, 95%CI: 0.08-2.5) Absorb BVS vs. 1/701 (0.5%, 95%CI: 0.2-1.6) EES; OR 3.04; 95%CI 1.2-7.68, P = 0.03], 92% of the VLDT in the BVS group occurred in the absence of dual antiplatelet therapy (DAPT). Patients treated with Absorb BVS had a trend towards higher risk of TLF (OR 1.48, 95%CI 0.90-2.42, P = 0.09), driven by a higher risk of target vessel myocardial infarction and ischaemia-driven target lesion revascularization. No difference was found in the risk of cardiac death.

Conclusion

Compared with EES, the use of Absorb BVS was associated with a higher rate of DT and a trend towards higher risk of TLF. VLDT occurred in 1.4% of the patients, the majority of these events occurred in the absence of DAPT.

Bioresorbable Coronary Scaffolds: Deployment Tips and Tricks and the Future of the Technology

Bioresorbable scaffolds (BRS) were developed as an alternative to drug-eluting stents (DES) to facilitate vessel restoration and reduce the risk of future adverse events. However, recent meta-analyses and "real-world" registries have raised some concern about the safety of this novel technology, especially due to an increased risk of thrombosis within the first weeks of scaffold implantation. These devices appear to be less forgiving to poor implantation strategies when compared to contemporary DES. Moreover, problems with the first generation of these devices-bulky struts and high crossing prolife, prolonged resorption time, lack of x-ray visibility, and limited tolerance to postdilation-have restricted their clinical application and negatively impacted their short- to mid-term safety performance. However, the potential for long-term improvements has encouraged further research into strategies to overcome these limitations, and potentially safer next-generation devices are already undergoing in-human clinical evaluations. Based on the current literature and our center's experience with these devices, this review discusses various approaches to optimize BRS implantation, drawbacks related to current-generation BRS, and potentially advantageous features of three next-generation scaffold systems.

Impact of PSP Technique on Clinical Outcomes Following Bioresorbable Scaffolds Implantation

Bioresorbable scaffolds (BRS) were introduced in clinical practice to overcome the long-term limitations of newer-generation drug-eluting stents. Despite some initial promising results of the Absorb BRS, safety concerns have led to the discontinuation of the commercialization of this device. Several retrospective studies have assessed the impact of the so-called Pre-dilation, Sizing and Post-dilation (PSP) technique concluding that an optimal PSP technique can improve clinical outcomes following BRS implantation. In this article, the definition of the PSP technique, and the current evidence of its impact on clinical outcomes are put in perspective. Additionality, the relationship between the PSP technique and the dual-antiplatelet therapy to prevent scaffold thrombosis is addressed. Finally, the future perspectives of BRS technology in clinical practice are commented.

Coronary Bioresorbable Vascular Scaffold Use in the Treatment of Coronary Artery Disease

Bioresorbable vascular scaffolds (BVS) represent a promising novel approach for the treatment of coronary artery disease. BVS promise to address some of the well-known limitations of current drug-eluting stents, while providing a transient scaffolding of the vessel to prevent acute vessel closure/recoil. Drug elution by BVS prevents neointimal proliferation in a similar fashion to drug-eluting stents, and complete bioresorption is associated with late vessel lumen enlargement, plaque regression, and restoration of vasomotion. Based on the pathophysiological reasons and on the results derived from clinical studies, BVS are increasingly being used in clinical practice. The aim of this review is to provide an overview of the current evidence supporting the use of BVS in clinical practice. In particular, we will discuss the randomized controlled trials and registries evaluating the clinical outcome of these devices, with a special focus on their application in patients with acute coronary syndrome and in specific lesion subsets (bifurcations, chronic total occlusions, and in-stent restenosis).

Optical coherence tomography guidance during bioresorbable vascular scaffold implantation

Bioresorbable vascular scaffold (BRS) represent a revolutionary concept in interventional cardiology. After initial enthusiasm, recent real world registries, including patients with increasing lesion complexity, reported not trivial rates of scaffold thrombosis (ScT). The importance of correct patients selection as well as technical aspects during BRS implantation procedures has been highlighted in several studies suggesting that the high rate of ScT might be related to uncorrected patients/lesions selection together with underutilization of intracoronary imaging guidance leading to suboptimal BRS implantation. The high-resolution power together with the lack of shadowing observed beyond polymer struts makes optical coherence tomography (OCT) the optimal imaging technique to guide BRS implantation and identifies eventually scaffolds failures.

Mechanical behavior of polymer-based vs. metallic-based bioresorbable stents

Bioresorbable scaffolds (BRS) were developed to overcome the drawbacks of current metallic drug-eluting stents (DES), such as late in-stent restenosis and caging of the vessel permanently. The concept of the BRS is to provide transient support to the vessel during healing before being degraded and resorbed by the body, freeing the vessel and restoring vasomotion. The mechanical properties of the BRS are influenced by the choice of the material and processing methods. Due to insufficient radial strength of the bioresorbable material, BRS often required large strut profile as compared to conventional metallic DES. Having thick struts will in turn affect the deliverability of the device and may cause flow disturbance, thereby increasing the incidence of acute thrombotic events. Currently, the bioresorbable poly-l-lactic acid (PLLA) polymer and magnesium (Mg) alloys are being investigated as materials in BRS technologies. The bioresorption process, mechanical properties, in vitro observations and clinical outcomes of PLLA-based and Mg-based BRS will be examined in this review.

Everolimus-eluting bioresorbable vascular scaffolds for treatment of complex chronic total occlusions

AIMS

Bioresorbable vascular scaffolds (BVS) represent a novel therapeutic option for the treatment of coronary artery diseases. The objective of this study was to evaluate the feasibility of BVS implantation in complex chronic total occlusions (CTO).

METHODS AND RESULTS

The present report is a multicentre registry evaluating results after BVS deployment in challenging CTO lesions, defined as J-CTO score ≥2 (difficult or very difficult). A total of 105 patients were included in the present analysis. The mean J-CTO score was 2.61 (difficult 52.4%, very difficult 47.6%). Device success and procedural success rates were 98.1% and 97.1%, respectively. The retrograde approach was used in 25.7% of cases. After wire crossing, predilatation was performed in all cases with a mean predilatation balloon diameter of 2.73±0.43 mm. The mean scaffold length was 59.75±25.85 mm, with post-dilatation performed in 89.5% of the cases and a mean post-dilatation balloon diameter of 3.35±0.44 mm. Post-PCI minimal lumen diameter was 2.50±0.51 mm and percentage diameter stenosis 14.53±10.31%. At six-month follow-up, a total of three events were reported: one periprocedural myocardial infarction, one late scaffold thrombosis and one additional target lesion revascularisation.

CONCLUSIONS

The present report suggests the feasibility of BVS implantation in complex CTO lesions, given adequate lesion preparation and post-dilatation, with good acute angiographic results and midterm clinical outcomes.

Randomized Comparison of Absorb Bioresorbable Vascular Scaffold and Mirage Microfiber Sirolimus-Eluting Scaffold Using Multimodality Imaging

OBJECTIVES

The primary objective of this study was to evaluate the safety and effectiveness of the Mirage (Manli Cardiology, Singapore) bioresorbable microfiber sirolimus-eluting scaffold compared with the Absorb (Abbott Vascular, Santa Clara, California) bioresorbable vascular scaffold in the treatment of stenotic target lesions located in native coronary arteries, ranging from ≥2.25 to ≤4.0 mm in diameter. Secondary objectives were to establish the medium-term safety, effectiveness, and performance of the Mirage device.

BACKGROUND

The current generation of bioresorbable scaffolds has several limitations, such as thick square struts with large footprints that preclude their deep embedment into the vessel wall, resulting in protrusion into the lumen with microdisturbance of flow. The Mirage sirolimus-eluting bioresorbable microfiber scaffold is designed to address these concerns.

METHODS

In this prospective, single-blind trial, 60 patients were randomly allocated in a 1:1 ratio to treatment with a Mirage sirolimus-eluting bioresorbable microfiber scaffold or an Absorb bioresorbable vascular scaffold. The clinical endpoints were assessed at 30 days and at 6 and 12 months. In-device angiographic late loss at 12 months was quantified. Secondary optical coherence tomographic endpoints were assessed post-scaffold implantation at 6 and 12 months.

RESULTS

Median angiographic post-procedural in-scaffold minimal luminal diameters of the Mirage and Absorb devices were 2.38 mm (interquartile range [IQR]: 2.06 to 2.62 mm) and 2.55 mm (IQR: 2.26 to 2.71 mm), respectively; the effect size (d) was -0.29. At 12 months, median angiographic in-scaffold minimal luminal diameters of the Mirage and Absorb devices were not statistically different (1.90 mm [IQR: 1.57 to 2.31 mm] vs. 2.29 mm [IQR: 1.74 to 2.51 mm], d = -0.36). At 12-month follow-up, median in-scaffold late luminal loss with the Mirage and Absorb devices was 0.37 mm (IQR: 0.08 to 0.72 mm) and 0.23 mm (IQR: 0.15 to 0.37 mm), respectively (d = 0.20). On optical coherence tomography, post-procedural diameter stenosis with the Mirage was 11.2 ± 7.1%, which increased to 27.4 ± 12.4% at 6 months and remained stable (31.8 ± 12.9%) at 1 year, whereas the post-procedural optical coherence tomographic diameter stenosis with the Absorb was 8.4 ± 6.6%, which increased to 16.6 ± 8.9% and remained stable (21.2 ± 9.9%) at 1-year follow-up (Mirage vs. Absorb: d_{post-procedure} = 0.41, d_{6 months} = 1.00, d_{12 months} = 0.92). Angiographic median in-scaffold diameter stenosis was significantly different between study groups at 12 months (28.6% [IQR: 21.0% to 40.7%] for the Mirage, 18.2% [IQR: 13.1% to 31.6%] for the Absorb, d = 0.39). Device- and patient-oriented composite endpoints were comparable between the 2 study groups.

CONCLUSIONS

At 12 months, angiographic in-scaffold late loss was not statistically different between the Mirage and Absorb devices, although diameter stenosis on angiography and on optical coherence tomography was significantly higher with the Mirage than with the Absorb. The technique of implantation was suboptimal for both devices, and future trials should incorporate optical coherence tomographic guidance to allow optimal implantation and appropriate assessment of the new technology, considering the novel mechanical properties of the Mirage.

Biodegradable Cable-Tie Rapamycin-eluting Stents

"Cable-tie" type biodegradable stents with drug-eluting nanofiber were developed to treat rabbit denuded arteries in this study. Biodegradable stents were fabricated using poly-L-lactide film following being cut and rolled into a cable-tie type stent. Additionally, drug-eluting biodegradable nanofiber tubes were electrospun from a solution containing poly (lactic-co-glycolic acid), rapamycin, and hexafluoroisopropanol, and then mounted onto the stents. The fabricated rapamycin-eluting cable-tie stents exhibited excellent mechanical properties on evaluation of compression test and collapse pressure, and less than 8% weight loss following being immersed in phosphate-buffered saline for 16 weeks. Furthermore, the biodegradable stents delivered high rapamycin concentrations for over 4 weeks and achieved substantial reductions in intimal hyperplasia associated with elevated heme oxygenase-1 and calponin level on the denuded rabbit arteries during 6 months of follow-up. The drug-eluting cable-tie type stents developed in this study might have high potential impacts for the local drug delivery to treat various vascular diseases.

Anti-thrombotic technologies for medical devices

Thrombosis associated with medical devices may lead to dramatic increases in morbidity, mortality and increased health care costs. Innovative strategies are being developed to reduce this complication and provide a safe biocompatible interface between device and blood. This article aims to describe the biological phenomena underlying device-associated thrombosis, and surveys the literature describing current and developing technologies designed to overcome this challenge. To reduce thrombosis, biomaterials with varying topographical properties and incorporating anti-thrombogenic substances on their surface have demonstrated potential. Overall, there is extensive literature describing technical solutions to reduce thrombosis associated with medical devices, but clinical results are required to demonstrate significant long-term benefits.

Bioresorbable Vascular Scaffolds for the Treatment of Chronic Total Occlusions: An International Multicenter Registry

BACKGROUND

There are only limited studies reporting clinical outcomes after bioresorbable vascular scaffold (BVS; Absorb; Abbott Vascular, Santa Clara, CA) implantation for coronary chronic total occlusions (CTO). The aim of this study was to evaluate the real-world feasibility and safety of BVS implantation for the treatment of CTO.

METHODS AND RESULTS

We retrospectively evaluated CTO cases treated with BVS from a multicenter registry. The primary end point was target lesion failure defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target lesion revascularization. From September 2012 to November 2015, 65 patients with CTO were successfully treated with BVS. The mean age of patients was 60.8±11.0 years; 89.2% were male and 40.0% diabetic. The mean ejection fraction was 57.7±10.8%. The mean reference vessel diameter and CTO lesion length were 3.0±0.4 and 20.2±3.0 mm, respectively. The mean number of BVS deployed per patient was 1.8±0.7, of which mean diameter and total length were 3.0±0.4 and 47.6±19.9 mm, respectively. Postdilatation with noncompliant balloons (mean diameter 3.3±0.3 mm) was performed at high pressures (18.6±5.3 atm) in all cases. Intravascular ultrasound (n=34) or optical coherence tomography (n=31) was performed in all cases. During the follow-up period (median: 453 days, 25th and 75th percentiles: 230 and 703), there were no occurrences of target lesion failure or scaffold thrombosis.

CONCLUSIONS

BVS implantation for the treatment of CTO seems feasible and safe. Appropriate lesion preparation, high-pressure postdilatation, and the use of intravascular imaging are recommended to obtain the best possible final result.

Overlapping implantation of bioresorbable novolimus-eluting scaffolds: an observational optical coherence tomography study

Overlapping implantation of bioresorbable vascular scaffolds is frequently necessary, but its influence on vessel and scaffold structure has not been thoroughly analyzed previously. The aim of this study was to analyze the acute effects of overlapping implantation on BRS as determined by optical coherence tomography (OCT). A total of 38 patients with de novo coronary artery stenoses who underwent OCT in the context of implantation of novolimus-eluting BRS (DESolve, Elixir Medical Corporation, Sunnyvale, California, USA) were investigated. In 15 patients, overlapping implantation of two BRS was performed, while 23 patients with implantation of one single BRS served as the control group. OCT data were retrospectively analyzed regarding acute scaffold implantation results. There were no significant differences between the overlap and control group in terms of residual in-scaffold area stenosis, scaffold area, mean or minimal lumen area, eccentricity index, incomplete scaffold apposition area or malapposition. While strut fracture was slightly more frequent in BRS with overlap its incidence was low overall. In patients with overlapping BRS, overlap segments did not display smaller lumen areas than segments without overlap (mean lumen area overlap: 8.16 ± 2.97 mm² vs. no overlap: 7.70 ± 2.55 mm²; p = 0.71; minimal lumen area overlap: 6.83 ± 2.71 mm² vs. no overlap: 6.17 ± 2.58 mm²; p = 0.37). Acute mechanical performance of novolimus-eluting BRS is not impaired by overlapping implantation. It can be assumed that vessel expansion compensates for the double scaffold layer in the overlap area resulting in a similar lumen area in overlap areas and in those with a single strut layer.

Bioabsorbable vascular scaffold overexpansion: insights from in vitro post-expansion experiments

AIMS

While bioresorbable vascular scaffolds (BVS) are increasingly used in clinical practice, their behaviour when post-dilated beyond their recommended maximum overexpansion diameter remains sparsely documented. We aimed to test the overexpansion of the BVS scaffold in vitro and evaluate the impact of excessive scaffold oversizing on focal point support.

METHODS AND RESULTS

We examined the post-expansion behaviour of the bioresorbable vascular scaffold (3.0 mm and 3.5 mm Absorb BVS; Abbott Vascular, Santa Clara, CA, USA) after overexpansion with non-compliant (NC) balloons of increasing diameters. After each oversizing step, the scaffolds were measured and inspected for strut disruption using microscope and optical coherence tomography imaging. Point force mechanical measurements on single scaffold struts were also performed to evaluate the impact of excessive scaffold overstretching on focal mechanical support. 3.0 mm and 3.5 mm scaffold sizes could be post-expanded up to 1 mm above their nominal diameters without any strut fracture when deployed without an external constraining model. Importantly, when overexpansion of both scaffold sizes was repeated using a constraining silicone lesion model, only post-expansion with an NC balloon size 0.5 mm larger than the scaffold nominal sizes could be performed without strut fractures. Point force compression analysis on single struts shows that overstretched struts with fractures provided lower focal strength compared to overexpanded ring segments without fractures and normal segments expanded at nominal pressure.

CONCLUSIONS

In our experiments, only overexpansion with an NC balloon 0.5 mm larger than the BVS size was feasible for BVS deployed inside an arterial lesion model. Overexpansion of the BVS scaffold beyond recommended post-dilation limits can lead to strut disconnections and focal loss of mechanical support.

Bioresorbable vascular scaffold thrombosis in a consecutive cohort of 550 patients

OBJECTIVE

To determine the rate of bioresorbable vascular scaffold (BVS) thrombosis in a large, real-world population.

BACKGROUND

There is some concern about device thrombosis after percutaneous coronary intervention (PCI) using BVS. No data have been published for PCI using both BVS and metal stents.

METHODS

A cohort of 550 consecutive patients who underwent PCI for stable chest pain or acute coronary syndromes with implantation of at least one BVS (Absorb, Abbott Vascular) was systematically followed up by telephone interview and review of medical charts. Data on device thrombosis were retrospectively analyzed in relationship to clinical and angiographic characteristics.

RESULTS

Follow-up was achieved in 533 patients (97%, median follow-up 233 days). A total of 964 BVS were implanted in 645 vessels. In addition, 234 metal stents were implanted in 149 patients, including "hybrid intervention" with the combined use of BVS and stents in the same artery in 122 patients. Documented were 15 definite, 1 probable, and 8 possible cases of device thrombosis (rate of definite/probable device thrombosis: 3.0%). Of these, 6 definite and 6 possible thromboses could be unambiguously attributed to BVS (1.1%), whereas a total of 11 definite, 1 probable, and 8 possible thromboses were potentially attributable to BVS (2.3%). Definite device thrombosis occurred in 7/122 patients with "hybrid intervention" (5.7%).

CONCLUSIONS

In a large real-world cohort treated with BVS, the rate of scaffold thrombosis was higher than published for randomized trials. A high rate of thrombosis was observed after combined implantation of BVS and stents within one vessel. © 2016 Wiley Periodicals, Inc.

Scaffold Thrombosis After Percutaneous Coronary Intervention With ABSORB Bioresorbable Vascular Scaffold: A Systematic Review and Meta-Analysis

OBJECTIVES

The aim of this study was to determine the risk of scaffold thrombosis (ST) after percutaneous coronary intervention (PCI) with placement of an ABSORB bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) by conducting a systematic review and meta-analysis.

BACKGROUND

PCI with BVS placement holds great potential, but concern has recently been raised regarding the risk of ST.

METHODS

MEDLINE/PubMed, Cochrane CENTRAL, and meeting abstracts were searched for all studies that included outcomes data for patients after PCI with BVS placement. For studies comparing BVSs with drug-eluting stents (DES), pooled estimates of outcomes, presented as odds ratios (ORs) with 95% confidence intervals (CIs), were generated with random-effects models.

RESULTS

Our analysis included 10,510 patients (8,351 with a BVS and 2,159 with DES) with a follow-up of 6.4 ± 5.1 months and 60 ± 11 years of age; 78% were male, 36% had stable angina, and 59% had acute coronary syndrome (ACS). Among patients with a BVS, cardiovascular death occurred in 0.6%, myocardial infarction (MI) in 2.1%, target lesion revascularization in 2.0%, and definite/probable ST in 1.2% of patients. Of BVS patients, 0.27% had acute ST and 0.57% had subacute ST. Meta-analysis demonstrated that patients who received a BVS were at a higher risk of MI (OR: 2.06, 95% CI: 1.31 to 3.22, p = 0.002) and definite/probable ST (OR: 2.06, 95% CI: 1.07 to 3.98, p = 0.03) compared with patients who received DES, whereas there was a trend toward decreased all-cause mortality with a BVS (OR: 0.40, 95% CI: 0.15 to 1.06, p = 0.06).

CONCLUSIONS

Patients undergoing PCI with a BVS had increased definite/probable ST and MI during follow-up compared with DES. Further studies with long-term follow-up are needed to assess the risk of ST with a BVS.

Post-dilatation after implantation of bioresorbable everolimus- and novolimus-eluting scaffolds: an observational optical coherence tomography study of acute mechanical effects

OBJECTIVES

The objective was to investigate the acute mechanical effects of post-dilatation on bioresorbable scaffolds (BRS) as determined by optical coherence tomography (OCT).

BACKGROUND

Post-dilatation with high-pressure balloons is regarded as a key component of BRS implantation for treatment of coronary artery stenoses. However, the impact of post-dilatation on BRS in vivo has not been thoroughly investigated.

METHODS

OCT was performed after the implantation procedure of 51 everolimus-eluting or novolimus-eluting polylactic acid-based BRS with (n = 27) or without non-compliant balloon post-dilatation (n = 24). The number of malapposed struts, strut fractures, edge dissections, residual in-scaffold area stenosis, and incomplete scaffold apposition area was analyzed over the complete length of each BRS with a spacing of 1 mm.

RESULTS

OCT revealed a significantly lower incomplete scaffold apposition area if post-dilatation was performed (0.16 ± 0.49 mm² with post-dilatation vs. 2.65 ± 2.78 mm² without post-dilatation, p < 0.001), as well as a significantly lower absolute number of malapposed struts (1 ± 2 with post-dilatation vs. 13 ± 13 without post-dilatation, p < 0.001). No significant differences regarding residual in-scaffold area stenosis, strut fracture, edge dissection, symmetry index, or eccentricity index were observed in patients with vs. without post-dilatation.

CONCLUSION

Post-dilatation of BRS with non-compliant balloons significantly reduces the number of malapposed struts and incomplete scaffold apposition area without inducing higher rates of edge dissection or strut fracture.

Neoatherosclerosis after Drug-Eluting Stent Implantation: Roles and Mechanisms

In-stent neoatherosclerosis (NA), characterized by a relatively thin fibrous cap and large volume of yellow-lipid accumulation after drug-eluting stents (DES) implantation, has attracted much attention owing to its close relationship with late complications, such as revascularization and late stent thrombosis (ST). Accumulating evidence has demonstrated that more than one-third of patients with first-generation DES present with NA. Even in the advent of second-generation DES, NA still occurs. It is indicated that endothelial dysfunction induced by DES plays a critical role in neoatherosclerotic development. Upregulation of reactive oxygen species (ROS) induced by DES implantation significantly affects endothelial cells healing and functioning, therefore rendering NA formation. In light of the role of ROS in suppression of endothelial healing, combining antioxidant therapies with stenting technology may facilitate reestablishing a functioning endothelium to improve clinical outcome for patients with stenting.

Impact of Implantation Technique and Plaque Morphology on Strut Embedment and Scaffold Expansion of Polylactide Bioresorbable Scaffold - Insights From ABSORB Japan Trial

BACKGROUND

The optimal implantation technique for the bioresorbable scaffold (Absorb, Abbott Vascular) is still a matter of debate. The purpose of the present study was to evaluate the effect of implantation technique on strut embedment and scaffold expansion.Methods and Results:Strut embedment depth and scaffold expansion index assessed by optical coherence tomography (OCT) (minimum scaffold area/reference vessel area) were evaluated in the ABSORB Japan trial (OCT subgroup: 87 lesions) with respect to implantation technique using either quantitative coronary angiography (QCA) or OCT. Strut embedment was assessed at the strut level (n=667), while scaffold expansion was assessed at the lesion level (n=81). The mean embedment depth was 63±59 µm. Balloon sizing and inflation pressure had no direct effect on strut embedment. Plaque morphology affected strut embedment [nonatherosclerotic (58.9±54.3 µm), fibroatheroma (73.3±59.6 µm), fibrous plaque (59.7±51.1 µm), and fibrocalcific plaque (-3.1±61.6 µm, negative value means malapposition), P <0.001]. The balloon-artery ratio positively correlated with the expansion index. This relationship was stronger when the OCT-derived reference vessel diameter (RVD) was used as a reference for balloon selection rather than the QCA-derived one [predilatation (Pearson correlation r: QCA: 0.167 vs. OCT: 0.552), postdilatation (QCA: 0.316 vs. OCT: 0.717)].

CONCLUSIONS

Underlying plaque morphology influenced strut embedment, whereas implantation technique had no direct effect on it. Optimal balloon sizing based on OCT-derived RVD might be recommended. However, the safety of such a strategy should be investigated in a prospective trial. (Circ J 2016; 80: 2317-2326).