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Aims: We sought to investigate two-year clinical and serial optical coherence tomography (OCT) outcomes after implantation of a fully bioresorbable vascular scaffold (BVS) or a cobalt-chromium everolimus-eluting stent (CoCr-EES)., Methods and Results: In the ABSORB Japan trial, 400 patients were randomised in a 2:1 ratio to BVS (N=266) or CoCr-EES (N=134). A pre-specified OCT subgroup (N=125, OCT-1 group) underwent angio-graphy and OCT post procedure and at two years. Overall, the two-year TLF rates were 7.3% and 3.8% in the BVS and CoCr-EES arms (p=0.18), respectively. Very late scaffold thrombosis (VLST) beyond one year was observed in 1.6% (four cases: all in non-OCT-1 subgroups) of the BVS arm, while there was no VLST in the CoCr-EES arm. In three cases, OCT at the time of or shortly after VLST demonstrated strut discontinuities, malapposition and/or uncovered struts. However, the vessel healing by two-year OCT was nearly complete in both BVS and CoCr-EES arms with almost fully covered struts, and minimal malapposition. The flow area by two-year OCT was smaller in the BVS arm than in the CoCr-EES arm, mainly due to tissue growth inside the device. However, there were no differences between the BVS and CoCr-EES with regard to the quality of homogenous tissues growing inside the devices., Conclusions: The rate of TLF was numerically higher in the BVS arm than in the CoCr-EES arm, although this difference was not statistically significant. VLST was observed only in the BVS arm at a rate of 1.6% between one and two years. Further studies are mandatory to investigate the risk of BVS relative to metallic stents for VLST, and the underlying mechanisms of BVS VLST.

Aims: To evaluate the implications of an Absorb bioresorbable vascular scaffold (Absorb BVS) on the morphology of the superficial plaques., Methods and Results: Forty-six patients who underwent Absorb BVS implantation and 20 patients implanted with bare metal stents (BMS) who had serial optical coherence tomographic examination at baseline and follow-up were included in this analysis. The thin-capped fibroatheromas (TCFA) were identified in the device implantation regions and in the adjacent native coronary segments. Within all regions, circumferential locations of TCFA and calcific tissues were identified, and the neointimal thickness was measured at follow-up. At six to 12-month follow-up, only 8% of the TCFA detected at baseline were still present in the Absorb BVS and 27% in the BMS implantation segment (p=0.231). Sixty percent of the TCFA in native segments did not change their phenotype at follow-up. At short-term follow-up, significant reduction in the lumen area of the BMS was noted, which was higher compared to that reported in the Absorb BVS group (-2.11±1.97 mm2 vs. -1.34±0.99 mm2, p=0.026). In Absorb BVS, neointima tissue continued to develop at midterm follow-up (2.17±0.48 mm2 vs. 1.38±0.52 mm2, p<0.0001) and covered the underlying tissues without compromising the luminal dimensions (5.93±1.49 mm2 vs. 6.14±1.49 mm2, p=0.571) as it was accommodated by the expanded scaffold (8.28±1.74 mm2 vs. 7.67±1.28 mm2, p<0.0001)., Conclusions: Neointimal tissue develops following either Absorb BVS or BMS implantation and shields lipid tissues. The neointimal response in the BMS causes a higher reduction of luminal dimensions compared to the Absorb BVS. Thus, Absorb BVS may have a value in the invasive re-capping of high-risk plaques.

Aims: To investigate the extent and the circumferential distribution of the neointima tissue developed following an Absorb bioresorbable vascular scaffold (BVS) implantation., Methods and Results: Twenty-three patients who were treated with the Absorb BVS and had optical coherence tomographic examination after scaffold implantation, at six-month and at two-year follow-up, were included in the current analysis. The lumen and the scaffold borders were detected and the circumferential thickness of the neointima was measured at one degree intervals. The symmetry of the neointima was defined as: minimum/maximum thickness. The lumen area was decreased at six months compared to baseline but it did not change between six-month and two-year follow-up (baseline: 7.49 [6.13-8.00] mm², six months: 6.31 (4.75-7.06) mm², two years: 6.01 [4.67-7.11] mm², p=0.373). However, the mean neointima thickness (six months: 189 [173-229] m, two years: 258 [222-283] m, p<0.0001) and the symmetry index of the neointima (six months: 0.06 [0.02-0.09], two years: 0.27 [0.24-0.36], p<0.0001) were increased at two years. Full circumferential coverage of the vessel wall by neointima tissue was seen in 91% of the studied frames at two years., Conclusions: This study demonstrates that after an Absorb BVS implantation neointima tissue develops that covers almost the whole circumference of the vessel wall. In contrast to the metallic stents, the neointima tissue does not compromise the luminal dimensions. Further research is required to evaluate the neointimal characteristics and assess the potential value of the device in passivating high-risk plaques.

Recommended techniques for bifurcation stenting continue to be revised with specific attention to bioresorbable scaffolds (BRS). Optimal procedural success and long-term outcomes with BRS can perhaps be improved with careful attention to implantation techniques. Good vessel preparation is imperative for optimal expansion of the scaffold, and proper vessel sizing is necessary to ensure compliance with scaffold expansion limits and preservation of proper scaffold function. The European Bifurcation Club (EBC) recommends provisional stenting for the majority of bifurcation lesions: permanent metallic stents are sized according to the distal vessel diameter, with subsequent post-dilatation of the proximal vessel to ensure stent apposition in the proximal main vessel. Recent BRS-specific modifications to the EBC recommendation suggest that selecting the scaffold size based on the diameter of the proximal main vessel can mitigate the risk of overexpansion and potential strut fracture. Expansion of the BRS requires a thoughtful balance between the risk of malapposition associated with underdeployment and the risk of strut fracture due to overdeployment. Post-dilatation of scaffolds should be performed, always respecting the maximum expansion limit, to correct any potential scaffold malapposition and minimise flow disturbances. Finally, dual antiplatelet therapy plays an important role in BRS bifurcation treatment to avoid thromboembolic events.

Aims: We aimed to investigate a fully bioresorbable poly-l-lactide (PLLA) scaffold to assess vascular remodelling in comparison to a permanent polymeric metal DES., Methods and Results: Twenty-five New Zealand white rabbits received an Absorb bioresorbable vascular scaffold (BVS, 1.0 and 1.1) or a CYPHER sirolimus-eluting stent (SES) in the iliac arteries. Twelve arteries were harvested at one month for scanning electron microscopy (SEM) analysis (BVS 1.1). The other implanted (BVS 1.0) arteries (n=32) were explanted at three, six and 36 months for light microscopic analysis. Re-endothelialisation assessed at one month was incomplete in both BVS and SES by SEM, with a trend towards greater coverage in SES (endothelialisation above strut: 32.2% vs. 60.6%, p=0.10). However, light microscopic analysis at later time points revealed greater endothelial coverage in BVS than in SES at 36 months (100.0% vs. 93.3%, p=0.05). Inflammation scores were comparable between arteries implanted with BVS and SES at three months (1.1 vs. 1.1, p=0.99), which decreased over time in the BVS implanted arteries (36 months: 0.0 vs. 0.2, p=0.05). At 36 months, BVS were completely resorbed, and resorption sites were replaced by connective tissue., Conclusions: BVS in the rabbit iliac artery model demonstrated ongoing vascular healing at three and six months, and complete vessel restoration, re-endothelialisation and no to minimal vascular inflammation at 36 months.

Aims: To assess observations with multimodality imaging of the Absorb bioresorbable everolimus-eluting vascular scaffold performed in two consecutive cohorts of patients who were serially investigated either at 6 and 24 months or at 12 and 36 months., Methods and Results: In the ABSORB multicentre single-arm trial, 45 patients (cohort B1) and 56 patients (cohort B2) underwent serial invasive imaging, specifically quantitative coronary angiography (QCA), intravascular ultrasound (IVUS), radiofrequency backscattering (IVUS-VH) and optical coherence tomography (OCT). Between one and three years, late luminal loss remained unchanged (6 months: 0.19 mm, 1 year: 0.27 mm, 2 years: 0.27 mm, 3 years: 0.29 mm) and the in-segment angiographic restenosis rate for the entire cohort B (n=101) at three years was 6%. On IVUS, mean lumen, scaffold, plaque and vessel area showed enlargement up to two years. Mean lumen and scaffold area remained stable between two and three years whereas significant reduction in plaque behind the struts occurred with a trend toward adaptive restrictive remodelling of EEM. Hyperechogenicity of the vessel wall, a surrogate of the bioresorption process, decreased from 23.1% to 10.4% with a reduction of radiofrequency backscattering for dense calcium and necrotic core. At three years, the count of strut cores detected on OCT increased significantly, probably reflecting the dismantling of the scaffold; 98% of struts were covered. In the entire cohort B (n=101), the three-year major adverse cardiac event rate was 10.0% without any scaffold thrombosis., Conclusions: The current investigation demonstrated the dynamics of vessel wall changes after implantation of a bioresorbable scaffold, resulting at three years in stable luminal dimensions, a low restenosis rate and a low clinical major adverse cardiac events rate., Clinical Trial Registration Information: http://www.clinicaltrials.gov/ct2/show/NCT00856856.

Aims: To assess serially the edge vascular response (EVR) of a bioresorbable vascular scaffold (BVS) compared to a metallic everolimus-eluting stent (EES)., Methods and Results: Non-serial evaluations of the Absorb BVS at one year have previously demonstrated proximal edge constrictive remodelling and distal edge changes in plaque composition with increase of the percent fibro-fatty (FF) tissue component. The 5 mm proximal and distal segments adjacent to the implanted devices were investigated serially with intravascular ultrasound (IVUS), post procedure, at six months and at two years, from the ABSORB Cohort B1 (n=45) and the SPIRIT II (n=113) trials. Twenty-two proximal and twenty-four distal edge segments were available for analysis in the ABSORB Cohort B1 trial. In the SPIRIT II trial, thirty-three proximal and forty-six distal edge segments were analysed. At the 5-mm proximal edge, the vessels treated with an Absorb BVS from post procedure to two years demonstrated a lumen loss (LL) of 6.68% (-17.33; 2.08) (p=0.027) with a trend toward plaque area increase of 7.55% (-4.68; 27.11) (p=0.06). At the 5-mm distal edge no major changes were evident at either time point. At the 5-mm proximal edge the vessels treated with a XIENCE V EES from post procedure to two years did not show any signs of LL, only plaque area decrease of 6.90% (-17.86; 4.23) (p=0.035). At the distal edge no major changes were evident with regard to either lumen area or vessel remodelling at the same time point., Conclusions: The IVUS-based serial evaluation of the EVR up to two years following implantation of a bioresorbable everolimus-eluting scaffold shows a statistically significant proximal edge LL; however, this finding did not seem to have any clinical implications in the serial assessment. The upcoming imaging follow-up of the Absorb BVS at three years is anticipated to provide further information regarding the vessel wall behaviour at the edges.

Aims: To analyse and to compare the changes in the various optical coherence tomography (OCT), echogenicity and intravascular ultrasound virtual histology (VH) of the everolimus-eluting bioresorbable scaffold (ABSORB) degradation parameters during the first 12 months after ABSORB implantation. In the ABSORB study, changes in the appearance of the ABSORB scaffold were monitored over time using various intracoronary imaging modalities. The scaffold struts exhibited a progressive change in their black core area by OCT, in their ultrasound derived grey level intensity quantified by echogenicity, and in their backscattering ultrasound signal, identified as "pseudo dense-calcium" (DC) by VH., Methods and Results: From the ABSORB Cohort B trial 35 patients had paired OCT, echogenicity and VH assessment at baseline and at six- (n=18) or 12-months follow-up (n=17). Changes in OCT strut core area, hyperechogenicity and VH-derived DC were analysed and compared at the various time points. At six months, the change (median[IQR]) in OCT strut core area was -7.2% (-14.0-+0.9) (p=0.053), in hyperechogenicity -12.7% (-33.7-+1.4) (p=0.048) and VH-DC 22.1% (-10.8-+48.8) (p=0.102). At 12 months, all the imaging modalities showed a decrease in the various parameters considered (OCT: -12.2% [-17.5--1.9], p=0.093; hyperechogenicity -24.64% [-36.6--16.5], p=0.001; VH-DC: -24.66% [-32.0--7.0], p=0.071). However, the correlation between the relative changes in these parameters was statistically poor (Spearman's rho <0.4)., Conclusions: OCT, echogenicity and VH were able to detect changes in the ABSORB scaffold struts, although the correlation between those changes was poor. This is likely due to the fact that each imaging modality interrogates different material properties on different length scales. Further studies are needed to explore these hypotheses.

Aims: Bioresorbable vascular scaffolds (BVS) present different mechanical properties as compared to metallic platform stents. Therefore, the standard procedural technique to achieve appropriate deployment may differ., Methods and Results: Fifty-two lesions treated with a 3 x 18 mm BVS were imaged with optical coherence tomography (OCT) post-implantation and screened for parameters suggesting non-optimal deployment. These included minimal scaffold area (minSA)<5 mm², residual area stenosis (RAS)>20%, edge dissections, incomplete scaffold/strut apposition (ISA)>5% and scaffold pattern irregularities. The angiographic proximal and distal maximal lumen diameters (DMAX) were measured by quantitative coronary angiography. Based on the DMAX values, the population was divided into three groups: DMAX <2.5 mm (n=13), DMAX between 2.5-3.3 mm (n=30) and DMAX >3.3 mm (n=9). All three groups presented with similar pre-implantation angiographic characteristics except for the vessel size and were treated with similar balloon/artery ratios. The group with a DMAX <2.5 mm presented with a higher percentage of lesions with minSA <5 mm² (30.8% vs. 10.0% vs. 0%; p=0.08) and edge dissections (61.5% vs. 33.3% vs. 11.1%; p=0.05). Lesions with >5% of ISA were significantly higher in the group with DMAX >3.3 mm (7.7% vs. 36.7% vs. 66.7%; p=0.02). RAS >20% was similar between all groups (46.2 vs. 53.3 vs. 77.8%; p=0.47) and scaffold pattern irregularities were only documented in three cases., Conclusions: BVS implantation guided with quantitative angiography may improve the OCT findings of optimal deployment. The clinical significance of these angiographic and OCT findings warranted long term follow-up of larger cohort of patients.

Aims: To compare the intravascular ultrasound virtual histology (IVUS-VH) appearance of the polymeric struts of the first (Revision 1.0) and the second (Revision 1.1) generation bioresorbable vascular scaffold (BVS)., Methods and Results: IVUS-VH misrepresents polymeric struts as dense calcium (DC) and necrotic core (NC) so that their presence and disappearance could be used as potential artifactual surrogate of bioresorption. DC and NC were assessed in both revisions of the BVS by analysing IVUS-VH from all patients in the ABSORB cohort A (Revision 1.0) and cohort B (Revision 1.1) study who had an IVUS-VH post-treatment and at 6-month follow-up. Post-treatment and 6-month follow-up IVUS-VH results, available in 60 patients (BVS 1.0 n=28; BVS 1.1 n=32), indicated an insignificant rise in DC+NC area compared to baseline with Revision 1.1 (0.10 ± 0.46 mm2, p=0.2), whilst a significant reduction was seen with Revision 1.0 (-0.57 ± 1.3 mm2, p=0.02). A significant correlation has been found between the change in the DC+NC area and the change in external elastic membrane area (y=0.68x-0.1; r=0.58, p=0.03)., Conclusions: Based on 6-months IVUS-VH analysis, the BVS 1.1 appears to have a different backscattering signal compared to the BVS 1.0, which may reflect differences in the speed of chemical and structural alteration.

Aims: Multimodality imaging of the first-in-man trial using a fully resorbable everolimus-eluting scaffold (BVS, Abbott Vascular, Santa Clara, CA, USA) demonstrated at two years the bioresorption of the device while preventing restenosis. Nevertheless, the long-term safety and efficacy of this novel therapy remain to be documented., Methods and Results: The ABSORB trial completed in July 2006 at four clinical sites in Europe and New Zealand the enrolment of 30 patients with a single de novo native coronary artery lesion. The major clinical endpoint was ischaemia-driven major adverse cardiac events (ID-MACE) defined as a composite of cardiac death, myocardial infarction, or ischaemia-driven target lesion revascularisation. Clinical follow-up was available in 29 patients since one patient withdrew consent. At 46 days, one patient experienced a single episode of chest pain and underwent a diagnostic optical coherence tomography and subsequently a target lesion revascularisation with slight troponin rise after the procedure. At 3-year the hierarchical ID-MACE of 3.4% remained unchanged. Clopidogrel therapy was discontinued in all but one patient. There has been no stent thrombosis reported. Two non-cardiac deaths were reported; one from duodenal perforation, the other from Hodgkin disease. Two patients underwent non-ischaemia driven target vessel revascularisation., Conclusions: Three-year clinical results have demonstrated a sustained low MACE rate (3.4%) without any late complication such as stent thrombosis.