The bioabsorption process: tissue and cellular mechanisms and outcomes

Durable-polymer versus biodegradable-polymer drug-eluting stents in acute coronary syndromes: three-year outcomes of the HOST REDUCE POLYTECH RCT Trial

BACKGROUND

Long-term follow-up is essential to evaluate the impact of polymer degradation in drug-eluting stents (DES).

AIMS

We aimed to compare durable-polymer DES (DP-DES) and biodegradable-polymer DES (BP-DES) during a 3-year follow-up to evaluate the entire period of polymer resolution (before, during, and after degradation).

METHODS

The HOST REDUCE POLYTECH RCT Trial was a randomised clinical trial enrolling patients with acute coronary syndrome (ACS) and comparing the efficacy and safety of DP-DES and BP-DES. The primary outcome was a patient-oriented composite outcome (POCO), and the key secondary outcome was a device-oriented composite outcome (DOCO).

RESULTS

A total of 3,413 ACS patients were randomised to either the DP-DES (1,713 patients) or BP-DES (1,700 patients) group. During the 3-year follow-up, the risk of the POCO was similar between the DP-DES and BP-DES groups (14.8% vs 15.4%, hazard ratio [HR] 0.96, 95% confidence interval [CI]: 0.80-1.14; p=0.613). However, the risk of the DOCO was lower in the DP-DES group (6.0% vs 8.0%, HR 0.73, 95% CI: 0.57-0.95; p=0.020). In a landmark analysis, the lower risk of the DOCO for the DP-DES group was evident during the transition from the early to the late period after percutaneous coronary intervention (PCI) (from 8 to 16 months post-PCI; 1.8% vs 3.3%, HR 0.54, 95% CI: 0.34-0.84; p=0.007), which was mainly driven by a risk reduction of target lesion revascularisation.

CONCLUSIONS

In ACS patients, DP-DES showed similar results to BP-DES regarding the POCO up to 3 years. For the DOCO, DP-DES were superior to BP-DES; this was due to the higher event rate during the period of polymer degradation.

Biolimus-eluting vs. other limus-eluting stents in NSTE-ACS: A pooled analysis of GLASSY and TWILIGHT

BACKGROUND

Biodegradable polymer biolimus-eluting stents (BP-BES) may be associated with better outcomes in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) compared to other current-generation limus-eluting stents (LES).

AIMS

To compare BP-BES with other current-generation LES in ACS patients undergoing PCI.

METHODS

We pooled individual data of Non-ST-segment elevation (NSTE)-ACS patients from two large randomized controlled trials (GLASSY and TWILIGHT). The BP-BES groups consisted mostly of GLASSY patients, while the control group (other current-generation LES) included exclusively TWILIGHT patients. The primary outcome was major adverse cardiovascular events (MACE), including cardiovascular death, myocardial infarction, or stent thrombosis; the key secondary outcome was target-vessel failure (TVF). To account for trial design differences, outcomes were assessed at 3 months (short-term) and between 3 and 12 months (long-term) after PCI and subsequently pooled to estimate the 12-month hazards.

RESULTS

Of 7107 and 6053 NSTE-ACS patients included in the short- and long-term analysis, 32.7% and 36.5% received a BP-BES, respectively. Risk of MACE associated with BP-BES versus other LES was similar at short-term (1.1% vs 1.3%, adjusted HR 0.86, 95%CI 0.53-1.38), lower at long-term (1.7% vs 3.1%, adjusted HR 0.49, 95%CI 0.34-0.72), and lower in the entire 12-month period (pooled adjusted HR 0.61, 95%CI 0.45-0.82). The cumulative 12-month risk of TVF was reduced with BP-BES (adjusted HR 0.52, 95%CI 0.38-0.70).

CONCLUSION

BP-BES was associated with lower 12-month risks of MACE and TVF compared to other current generation LES among NSTE-ACS patients treated with abbreviated or standard ticagrelor-based DAPT. These non-randomized findings are hypothesis-generating.

CONDENSED ABSTRACT

Differences in clinical outcomes may exist between biodegradable polymer biolimus-eluting stents (BP-BES) and other current-generation limus-eluting stent (LES) in patients with acute coronary syndrome (ACS). We pooled individual data of about 7000 Non-ST-segment elevation ACS patients undergoing PCI and treated with ticagrelor with or without aspirin from two large randomized controlled trials (GLASSY and TWILIGHT). BP-BES patients derived very largely from GLASSY and other LES patients from TWILIGHT. In this population, BP-BES compared to other current generation LES, were associated with a lower 12-month risk of major adverse cardiovascular events and target-vessel failure.

BioMatrix Versus Orsiro Stents for Coronary Artery Disease: A Multicenter, Randomized, Open-Label Study

BACKGROUND

Comparative studies of ultrathin-strut biodegradable polymer sirolimus-eluting stent (BP-SES) have reported promising results and validated its excellent outcomes in terms of safety and efficacy. However, there are limited studies comparing BP drug-eluting stents with struts of different thicknesses. We compared the long-term clinical outcomes of patients treated with an ultrathin-strut BP-SES or a thick-strut biodegradable polymer biolimus-eluting stent (BP-BES).

METHODS

The BIODEGRADE trial (Biomatrix and Orsiro Drug-Eluting Stents in Angiographic Result in Patients With Coronary Artery Disease) is a multicenter prospective randomized study comparing coronary revascularization in patients with ultrathin-strut BP-SES and thick-strut BP-BES with the primary end point of target lesion failure at 18 months posttreatment. We performed the prespecified analysis of 3-year clinical outcomes.

RESULTS

In total, 2341 patients were randomized to receive treatment with ultrathin-strut BP-SES (N=1175) or thick-strut BP-BES (N=1166). The 3-year incidence rate of target lesion failure was 3.2% for BP-SES and 5.1% for BP-BES (P=0.023). The difference was primarily due to differences in ischemia-driven target lesion revascularization (BP-SES, 1.5%; BP-BES, 2.8%; P=0.035) between groups. A landmark analysis of the late follow-up period showed significant differences in target lesion failure, with outcomes being better in BP-SES. Cardiac death and target lesion revascularization were significantly lower in the BP-SES group.

CONCLUSIONS

In a large, randomized trial, the long-term clinical outcome of target lesion failure at 3 years was significantly better among patients treated with the ultrathin-strut BP-SES. The results indicate the superiority of the ultrathin-strut BP-SES compared with the thick-strut BP-BES.

REGISTRATION

URL: https://clinicaltrials.gov; Unique identifier: NCT02299011.

Comparison of biodegradable and newer generation durable polymer drug-eluting stents with short-term dual antiplatelet therapy: a systematic review and Bayesian network meta-analysis of randomized trials comprising of 43,875 patients

Newer generation durable polymer drug-eluting stents (DP-DES) and biodegradable polymer DES (BP-DES) have similar efficacy with dual-antiplatelet therapy (DAPT) duration of > 6 months. However, this difference in outcomes have not been well studied in shorter DAPT regime. This study compares the safety and efficacy profiles of DP-DES and BP-DES based on short-term (1-3 months), intermediate-term (4-6 months) and standard DAPT (6-12 months) durations. A search was conducted on Embase and Medline for Randomized Controlled Trials (RCTs) comparing stent types, and DAPT durations. Primary endpoints include cardiac death, myocardial infarction (MI), definite stent thrombosis, stroke, target vessel revascularization (TVR) and major bleeding. Network analysis was conducted to summarize the evidence. A total of 15 RCTs involving 43,875 patients were included. DP-DES was associated with significantly lower major bleeding rates compared to BP-DES (RR 0.44, Crl 0.22-0.83) in short-term DAPT. Among DP-DES patients, short-term DAPT was associated with lower major bleeding risk compared to standard DAPT (RR 0.47, CrI 0.32-0.69). This favorable bleeding profile with short DAPT was not found in BP-DES patients. Cardiac death, MI, definite stent thrombosis, stroke and TVR rates were similar across the various DAPT durations and stent types. Our preliminary findings demonstrated comparable efficacy and safety outcomes between BP-DES and newer generation BP-DES across various DAPT durations. In patients requiring short DAPT, DP-DES had more favourable major bleeding profile compared to BP-DES, without compromising anti-thrombotic efficacy.

Five-year angiographic, OCT and clinical outcomes of a randomized comparison of everolimus and biolimus-eluting coronary stents with everolimus-eluting bioresorbable vascular scaffolds

Aims

To compare 5‐year angiographic, optical coherence tomography (OCT), and clinical outcomes between patients treated with bioresorbable vascular scaffolds (BVS) and drug‐eluting stents (DES).

Methods

The EverBio‐2 trial (Comparison of Everolimus‐ and Biolimus‐Eluting Coronary Stents with Everolimus‐Eluting Bioresorbable Vascular Scaffold) was a single‐center, assessor‐blinded, randomized controlled trial in which 240 patients were randomly allocated (1:1:1) to BVS, everolimus‐eluting (EES) or biolimus‐eluting (BES) DES. Clinical follow‐up was scheduled up to 5 years. All patients, alive and who did not have repeat revascularization of the target lesion during follow‐up were asked to return for angiographic follow‐up at 5 years.

Results

Five‐year angiographic follow‐up was completed in 122 patients (51%) and OCT analysis was performed in 86 (36%) patients. In‐stent late lumen loss was similar in both groups with 0.50 ± 0.38 mm in BVS versus 0.58 ± 0.36 mm in EES/BES, p = 0.20. Clinical follow‐up was complete in 232 patients (97%) at 5 years. The rate of the device‐oriented endpoint was 22% in the BVS and 18% in the EES/BES group (p = 0.49). The patient‐oriented composite endpoint occurred in 40% of BVS‐ and 43% of EES/BES‐treated patients (p = 0.72) at 5 years. No acute coronary syndrome due to stent thrombosis was detected after 2 years. Complete BVS strut resorption was observed at 5 years in the OCT subgroup.

Conclusion

Five‐year clinical outcomes were similar between BVS and DES patients as well as angiographic outcomes in a selected subgroup. However, a definitive conclusion cannot be drawn because the EverBio‐2 trial was not powered for clinical and angiographic endpoints at 5 years of follow‐up.

Late neointimal volume reduction is observed following biodegradable polymer-based drug eluting stent in porcine model

BACKGROUND

The BP-SES has an abluminally applied biodegradable polymer that is fully resorbed after 3-4 months but may have longer-lasting effects. The aim of this study was to determine the long-term vascular response to the novel Ultimaster™ sirolimus-eluting stent (BP-SES).

METHODS

BP-SESs, everolimus-eluting stents (DP-EESs), and bare metal stents were implanted in 22 coronary arteries of 15 mini-swine. All animals underwent optical frequent domain imaging (OFDI) to assess neointimal volume and quality at either 1 (n = 7) or 3 (n = 8) months and at 9 (n = 15) months and were euthanized at 9 months. Stents were subsequently histologically investigated to analyze the vascular response and maturity of neointimal tissue according to cell density.

RESULTS

OFDI revealed greater regression in neointimal volume from 3 to 9 months with BP-SESs than with DP-EESs (-0.6 ± 0.5 mm2 vs. 0.00 ± 0.4 mm2, p = 0.07). Although there was no significant difference between BP-SESs and DP-EESs in the inflammation score (BMS, BP-SES, and DP-EES: 0.1 ± 0.1, 0.3 ± 0.4, and 0.4 ± 0.4, respectively; p < 0.0001) in histological analysis, BP-SESs showed slightly greater maturity than DP-EESs (1.8 ± 0.3, 1.7 ± 0.3, and 1.6 ± 0.3, p = 0.09).

CONCLUSIONS

While both BP-SESs and DP-EESs showed minimal inflammatory responses at 9 months, BP-SESs showed a trend for greater neointimal maturity and regression, which may be related to earlier completion of the vascular response.

Critical evaluation of stents in coronary angioplasty: a systematic review

BACKGROUND

Coronary stents are routinely placed in the treatment and prophylaxis of coronary artery disease (CAD). Current coronary stent designs are prone to developing blockages: in-stent thrombosis (IST) and in-stent re-stenosis (ISR). This is a systematic review of the design of current coronary stent models, their structural properties and their modes of application, with a focus on their associated risks of IST and ISR. The primary aim of this review is to identify the best stent design features for reducing the risk of IST and ISR. To review the three major types of stents used in clinical settings today, determining best and relevant clinical practice by exploring which types and features of offer improved patient outcomes regarding coronary angioplasty. This information can potentially be used to increase the success rate of coronary angioplasty and stent technology in the future taking into account costs and benefits.

METHODS

Scientific databases were searched to find studies concerning stents. After the exclusion criteria were applied, 19 of the 3192 searched literature were included in this review. Studies investigating three major types of stent design were found: bare-metal stents (BMS), drug-eluting stents (DES) and bioresorbable stents (BRS). The number of participants varied between 14 and 1264. On average 77.4% were male, with a mean age of 64 years.

RESULTS

From the findings of these studies, it is clear that DES are superior in reducing the risk of ISR when compared to BMS. Conflicting results do not clarify whether BRS are superior to DES at reducing IST occurrence, although studies into newer BRS technologies show reducing events of IST to 0, creating a promising future for BRS showing them to be non-inferior. Thinner stents were shown to reduce IST rates, due to better re-endothelialisation. Scaffold material has also been shown to play a role with cobalt alloy stents reducing the risk of IST. This study found that thinner stents that release drugs were better at preventing re-blockages. Some dissolvable stents might be better at stopping blood clots blocking the arteries when compared to metal stents. The method and procedure of implanting the stent during coronary angioplasty influences success rate of these stents, meaning stent design is not the only significant factor to consider.

CONCLUSIONS

Positive developments in coronary angioplasty could be made by designing new stents that encompass all the most desirable properties of existing stent technology. Further work is needed to investigate the benefits of BRS in reducing the risk of IST compared to DES, as well as to investigate the effects of different scaffold materials on IST and ISR outcomes.

Long-term clinical outcomes of biodegradable polymer drug eluting stents versus second-generation durable polymer drug eluting stents for ST-segment elevation myocardial infarction

BACKGROUND

Biodegradable polymer drug eluting stents (BP-DES) may offer the advantage of vascular healing in ST-segment elevation myocardial infarction (STEMI). Long-term outcome data comparing BP-DES and second-generation durable polymer drug eluting stents (DP-DES) in STEMI is lacking. This study aims to compare the long-term clinical outcomes of BP-DES versus second-generation DP-DES in STEMI.

METHODS

This is an observational study of consecutive patients with STEMI who received either BP-DES (n = 854) or DP-DES (n = 708) during primary percutaneous coronary intervention (PCI) from 1st February 2007 to 31st December 2016. The primary outcome was target lesion failure (TLF), a composite of cardiac death, target vessel myocardial infarction (MI), and target lesion revascularization with follow up till 30th November 2019.

RESULTS

The baseline demographics, lesion and procedural characteristic were similar between the two groups except for more prior MI and chronic obstructive pulmonary disease in the BP-DES group. At a median follow up of 4.2 years (interquartile range: 2.6-6.2 years), the incidence of TLF was similar between BP-DES and DP-DES (adjusted hazard ratio [HR] 0.94, 95% confidence interval [CI] 0.70-1.26). Likewise, incidence of major adverse cardiovascular events (MACE: all-cause death, any MI or target vessel revascularization) and definite stent thrombosis were similar in both groups (MACE: adjusted HR 1.04, 95% CI 0.82-1.32; definite stent thrombosis: adjusted HR 1.06, 95% CI 0.31-3.64).

CONCLUSION

Among patients with STEMI who underwent primary PCI, BP-DES and DP-DES implantation was associated with similar long-term clinical outcomes.

REabsorbable vs. DUrable Polymer Drug-Eluting Stents in All-Comer PatiEnts: the REDUCE registry

BACKGROUND

While the superiority of reabsorbable-polymer drug-eluting stents (RP-DES) over bare-metal stents and first-generation durable-polymer (DP)-DES has been largely established, their advantage compared with new-generation DP-DES is still controversial. This study aimed was to compare clinical outcomes of all-comer patients undergoing percutaneous coronary intervention (PCI) with new generation DP-DES or RP-DES implantation.

METHODS

We prospectively enrolled 679 consecutive patients treated with PCI with RP-DES or DP-DES. The primary endpoint was the 1-year incidence of major adverse clinical events (MACE), a composite of death, myocardial infarction (MI), and target vessel revascularization (TVR). Target lesion revascularization (TLR) and definite stent thrombosis were also recorded.

RESULTS

A total of 439 (64.6%) received RP-DES and 240 (36.4%) received DP-DES. No significant difference in the incidence of MACE (5.9 vs. 4.9%; hazard ratio, 1.23; 95% confidence interval (CI), 0.61-2.49; P = 0.569), death (1.8 vs. 1.7%; hazard ratio, 1.09; 95% CI, 0.33-3.64; P = 0.882), MI (2.3 vs. 2.1%; hazard ratio, 1.05; 95% CI, 0.36-3.08; P = 0.927), TVR (2.3 vs. 1.3%; hazard ratio, 1.70; 95% CI, 0.47-6.20; P = 0.418), TLR (1.4 vs. 0.4%; hazard ratio, 3.06; 95% CI, 0.37-25.40; P = 0.301), and definite stent thrombosis (0.5 vs. 0.4%; hazard ratio, 1.09; 95% CI, 0.10-12.10; P = 0.942) was observed between RP-DES and DP-DES patients at 1-year follow-up. These results were confirmed in a propensity score-matched cohort (n = 134 per group).

CONCLUSION

In our registry including a real-world population of all-comer patients undergoing PCI, RP-DES, or durable polymer-DES showed similar efficacy and safety at a 1-year follow-up.

Impact of different coronary angioscopic findings on arterial healing one year after bioresorbable-polymer and second-generation durable-polymer drug-eluting stent implantation

BACKGROUND

The advantage of using bioresorbable-polymer drug-eluting stent (BP-DES) compared with second-generation durable-polymer drug-eluting stent (2G DP-DES) still remains controversial in clinical situations. The purpose of this study to evaluate the degree of re-endothelialization and the prevalence of high-grade yellow-colored plaque (YCP), which might concern arterial healing after BP-DES and 2G DP-DES implantation using a high-resolution coronary angioscopy (CAS).

METHODS

In total, 104 DESs (52: 2G DP-DES and 52: BP-DES) were prospectively observed using CAS 12±1 months after coronary intervention. The grade of neointimal coverage (NIC) over the stent was scored on a 4-point scale from 0 (no coverage) to 3 (complete coverage). YCP grade was also scored on a 4-point scale as 0 (white) to 3 (intensive yellow). High-grade YCP was defined as maximum grade ≥2. Moreover, the prevalence of high-grade YCP and the incidence of thrombus were investigated.

RESULTS

BP-DES revealed better dominant NIC grade and less NIC heterogeneity than 2G DP-DES (p=0.0001 and p=0.015, respectively). The prevalence of high-grade YCP was lower for BP-DES than for 2G DP-DES (p=0.05). However, the incidence of thrombus was not significantly different (p=0.41). Multivariate analysis identified that low-density lipoprotein cholesterol levels [odds ratio (OR), 1.03; 95% Confidence Interval (CI): 1.01-1.06, p=0.01] and the usage of BP-DES [OR, 0.36; 95% CI: 0.14-0.91, p=0.03] as independent predictors of high-grade YCP.

CONCLUSIONS

Compared with 2G DP-DES, BP-DES was less heterogeneous and well-covered NIC and less prevalence of the high-grade YCP implying optimal arterial healing.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

One-year outcomes of a NeoHexa sirolimus-eluting coronary stent system with a biodegradable polymer in all-comers coronary artery disease patients: Results from NeoRegistry in India

BACKGROUND

Biodegradable polymer drug-eluting stents (BP-DES) have shown to reduce restenosis rates and have low rates of stent thrombosis. The present postmarketing surveillance assessed 1-year clinical outcomes of patients who had received NeoHexa DES in real practice.

AIM

To investigate 1-year clinical outcomes of Neohexa DES in real practice.

METHODS

Data obtained from a single-center cohort of patients who had received NeoHexa stents as part of routine treatment of coronary artery disease (CAD) were retrospectively investigated. The primary study endpoint was the rate of major adverse cardiac events (MACEs) defined as the composite of death, myocardial infarction (MI), and target lesion revascularization (TLR) during the follow-up at 1 mo, 6 mo, and 1 year after the index procedure.

RESULTS

A total of 129 patients with 172 lesions were enrolled. The most common comorbid conditions were hypertension (49.61%) and diabetes mellitus (39.53%). Procedural success was achieved in all patients, and no in-hospital MACE was reported. The incidence of composite MACE at 30 d, 6 mo, and 1 year was 0.78%, 3.94%, and 4.87%, respectively. The rate of possible and probable late stent thrombosis was 0.78%. The cumulative incidences of death, MI, and TLR at 1 year were 2.44%, 0.81%, and 1.63%, respectively.

CONCLUSION

The relatively low rates of MACE and stent thrombosis in this study support safety and performance of NeoHexa stents, suggesting it to be an effective alternative to other contemporary stents for the treatment of de novo lesions in native coronary arteries.

Impact of bioresorbable versus permanent polymer on longterm vessel wall inflammation and healing: a comparative drug-eluting stent experimental study

AIMS

Drug-eluting stents (DES) have evolved to using bioresorbable polymers as a method of drug delivery. The impact of bioresorbable polymer on long-term neointimal formation, inflammation, and healing has not been fully characterised. This study aimed to evaluate the biological effect of polymer resorption on vascular healing and inflammation.

METHODS AND RESULTS

A comparative DES study was performed in the familial hypercholesterolaemic swine model of coronary stenosis. Permanent polymer DES (zotarolimus-eluting [ZES] or everolimus-eluting [EES]) were compared to bioresorbable polymer everolimus-eluting stents (BP-EES) and BMS. Post implantation in 29 swine, stents were explanted and analysed up to 180 days. Area stenosis was reduced in all DES compared to BMS at 30 days. At 180 days, BP-EES had significantly lower area stenosis than EES or ZES. Severe inflammatory activity persisted in permanent polymer DES at 180 days compared to BP-EES or BMS. Qualitative para-strut inflammation areas (graded as none to severe) were elevated but similar in all groups at 30 days, peaked at 90 days in DES compared to BMS (p<0.05) and, at 180 days, were similar between BMS and BP-EES but were significantly greater in DES.

CONCLUSIONS

BP-EES resulted in a lower net long-term reduction in neointimal formation and inflammation compared to permanent polymer DES in an animal model. Further study of the long-term neointima formation deserves study in human clinical trials.

Comparison between two biodegradable polymer-based sirolimus-eluting stents with differing drug elution and polymer absorption kinetics: two-year clinical outcomes of the PANDA III trial

AIMS

In the PANDA III trial, the novel poly-lactide-co-glycolide polymer-based BuMA sirolimus-eluting stent (SES) was non-inferior to the polylactide polymer-based Excel SES for the primary endpoint of one-year target lesion failure (TLF), with a lower incidence of stent thrombosis. We sought to investigate whether the effectiveness profile of BuMA SES, with more rapid drug elution and polymer absorption kinetics, would persist at two years.

METHODS AND RESULTS

A total of 2,348 patients (mean age, 61.2±10.6 years; 24.3% diabetics; 31.2% with acute myocardial infarction within one month) were randomly assigned to receive either BuMA SES (n=1,174) or Excel SES (n=1,174) in the "all-comer" PANDA III trial. Two-year clinical follow-up was available for 2,262 (96.3%) patients. The incidence of TLF and the patient-oriented composite endpoint (PoCE) was low and similar between the BuMA and Excel groups (7.4% vs. 6.9%, p=0.67, and 13.1% vs. 10.9%, p=0.11, respectively). The rate of any revascularisation was significantly higher with the BuMA SES (6.8% vs. 4.6%, p=0.03). Definite and probable thrombosis occurred in 0.7% and 1.4% of patients in the BuMA and Excel groups, respectively (p=0.10).

CONCLUSIONS

Two-year rates of TLF and PoCE events were low and similar between the two biodegradable polymer-based SES.

Bioresorbable polymer-coated thin strut sirolimus-eluting stent vs durable polymer-coated everolimus-eluting stent in daily clinical practice: Propensity matched one-year results from interventional cardiology network registry

OBJECTIVES

We sought to determine the 1-year clinical follow-up in patients treated with the thin strut (71 μm) bioabsorbable polymer-coated sirolimus-eluting stent (BP-SES) vs durable coating everolimus eluting stent (DP-EES) in daily clinical routine.

BACKGROUND

Presence of durable polymers may be associated with late/very late stent thrombosis occurrence and the need for prolonged dual antiplatelet therapy. Bioabsorbable polymers may facilitate stent healing, thus enhancing clinical safety.

METHODS

Interventional Cardiology Network Registry is a prospective, multicenter, observational registry of 21,400 consecutive patients treated with PCI since 2010. We analyzed 4,670 patients treated with either a BP-SES (ALEX, Balton, Poland) or DP-EES (XIENCE, Abbott, USA) with available 1-year clinical follow-up using propensity-score matching. Outcomes included target vessel revascularization (TVR) as efficacy outcome and all cause death, myocardial infarction (MI), and definite/probable stent thrombosis as safety outcomes.

RESULTS

After propensity score matching, 1,649 patients treated with BP-SES and 1,649 patients treated with DP-EES were selected. Procedural and clinical characteristics were similar between both groups. There was no significant difference between tested groups in in-hospital mortality. One-year follow-up demonstrated comparable efficacy outcome, TVR (BP-SES 5.9% vs DP-EES 4.6% P = 0.45), as well as comparable safety outcomes, all cause death, MI and definite/probable stent thrombosis.

CONCLUSIONS

In this multicenter registry, the BP-SES thin strut biodegradable polymer-coated sirolimus-eluting stent demonstrated comparable clinical outcomes at 1-year after implantation to the DP-EES. These data support the relative safety and efficacy of DP-SES in a broad range of patients undergoing percutaneous coronary intervention.

Cardiovascular stents: overview, evolution, and next generation

Compared to bare-metal stents (BMSs), drug-eluting stents (DESs) have been regarded as a revolutionary change in coronary artery diseases (CADs). Releasing pharmaceutical agents from the stent surface was a promising progress in the realm of cardiovascular stents. Despite supreme advantages over BMSs, in-stent restenosis (ISR) and long-term safety of DESs are still deemed ongoing concerns over clinically application of DESs. The failure of DESs for long-term clinical use is associated with following factors including permanent polymeric coating materials, metallic stent platforms, non-optimal drug releasing condition, and factors that have recently been supposed as contributory factors such as degradation products of polymers, metal ions due to erosion and degradation of metals and their alloys utilizing in some stents as metal frameworks. Discovering the direct relation between stent materials and associating adverse effects is a complicated process, and yet it has not been resolved. For clinical success it is of significant importance to optimize DES design and explore novel strategies to overcome all problems including inflammatory response, delay endothelialization, and sub-acute stent thrombosis (ST) simultaneously. In this work, scientific reports are reviewed particularly focusing on recent advancements in DES design which covers both potential improvements of existing and recently novel prototype stent fabrications. Covering a wide range of information from the BMSs to recent advancement, this study mostly sheds light on DES's concepts, namely stent composition, drug release mechanism, and coating techniques. This review further reports different forms of DES including fully biodegradable DESs, shape-memory ones, and polymer-free DESs.

Meta-Analysis of Randomized Clinical Trials Comparing Biodegradable Polymer Drug-Eluting Stent to Second-Generation Durable Polymer Drug-Eluting Stents

OBJECTIVES

The authors sought to perform a meta-analysis of randomized clinical trials (RCTs) comparing the safety and efficacy of biodegradable polymer drug-eluting stents (BP-DES) to second-generation durable polymer drug-eluting stents (DP-DES).

BACKGROUND

Prior meta-analyses have established the superiority of BP-DES over bare-metal stents and first-generation DP-DES; however, their advantage compared with second-generation DP-DES remains controversial.

METHODS

The authors searched PubMed and Scopus databases for RCTs comparing BP-DES to the second-generation DP-DES. Outcomes included target vessel revascularization (TVR) as efficacy outcome and cardiac death, myocardial infarction (MI), and definite or probable stent thrombosis (ST) as safety outcomes. In addition, we performed landmark analysis for endpoints beyond 1 year of follow-up and a subgroup analysis based on the stent characteristics.

RESULTS

The authors included 16 RCTs comprising 19,886 patients in the meta-analysis. At the longest available follow-up (mean duration 26 months), we observed no significant differences in TVR (p = 0.62), cardiac death (p = 0.46), MI (p = 0.98), or ST (risk ratio: 0.83, 95% confidence interval: 0.64 to 1.09; p = 0.19). Our landmark analysis showed that BP-DES were not associated with a reduction in the risk of very late ST (risk ratio: 0.87, 95% confidence interval: 0.49 to 1.53; p = 0.62). Similar outcomes were seen regardless of the eluting drug (biolimus vs. sirolimus), the stent platform (stainless steel vs. alloy), the kinetics of polymer degradation or drug release (<6 months vs. >6 months), the strut thickness of the BP-DES (thin <100 μm vs. thick >100 μm), or the DAPT duration (≥6 months vs. ≥12 months).

CONCLUSIONS

BP-DES have similar safety and efficacy profiles to second-generation DP-DES.

Long-term in vivo corrosion behavior, biocompatibility and bioresorption mechanism of a bioresorbable nitrided iron scaffold

Pure iron as a potential bioresorbable material for bioresorbable coronary scaffold has major disadvantages of slow corrosion and bioresorption. However, so far, there are neither quantitative data of long-term in vivo corrosion nor direct experimental evidence for bioresorption of pure iron and its alloys, which are fundamental and vital for developing novel Fe-based alloys overcoming the intrinsic drawbacks of pure iron. This work systemically investigated scaffold performance, long-term in vivo corrosion behavior and biocompatibility of a nitrided iron coronary scaffold and explored its bioresorption mechanism. It was found that the 70μm Fe-based scaffold was superior to a state of the art Co-Cr alloy stent (Xience Prime™) in terms of crossing profile, recoil and radial strength. Mass loss was 76.0±8.5wt% for the nitrided iron scaffold and 44.2±11.4wt% for the pure iron scaffold after 36months implantation in rabbit abdominal aorta (p<0.05). The Fe-based scaffold showed good long-term biocompatibility in both rabbit and porcine model. Its insoluble corrosion products were demonstrated biosafe and could be cleared away by macrophages from in situ to adventitia to be indiscernible by Micro Computed Tomography and probably finally enter the lymphatics and travel to lymph nodes after 53months implantion in porcine coronary artery. The results indicate that the nitrided iron scaffold with further improvements shall be promising for coronary application.

STATEMENT OF SIGNIFICANCE

Pure iron as a potential bioresorbable material has major disadvantages of slow corrosion and bioresorption. However, so far, there are neither quantitative data of long-term in vivo corrosion nor direct experimental evidence for bioresorption of pure iron and its alloys. Only this work systemically investigated long-term in vivo corrosion behavior and biocompatibility of a nitrided iron coronary scaffold up to 53months after implantation and explored its bioresorption mechanism. These are fundamental and vital for developing novel Fe-based alloys overcoming the intrinsic drawbacks of pure iron. Novel testing and section-preparing methods were also provided in this work to facilitate future research and development of novel Fe-based alloy scaffolds.

The edge vascular response following implantation of the Absorb everolimus-eluting bioresorbable vascular scaffold and the XIENCE V metallic everolimus-eluting stent. First serial follow-up assessment at six months and two years: insights from the first-in-man ABSORB Cohort B and SPIRIT II trials

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.

Biodegradable polymer stents vs second generation drug eluting stents: A meta-analysis and systematic review of randomized controlled trials

AIM: To evaluate the premise, that biodegradable polymer drug eluting stents (BD-DES) could improve clinical outcomes compared to second generation permanent polymer drug eluting stents (PP-DES), we pooled the data from all the available randomized control trials (RCT) comparing the clinical performance of both these stents.

METHODS: A systematic literature search of PubMed, Cochrane, Google scholar databases, EMBASE, MEDLINE and SCOPUS was performed during time period of January 2001 to April 2015 for RCT and comparing safety and efficacy of BD-DES vs second generation PP-DES. The primary outcomes of interest were definite stent thrombosis, target lesion revascularization, myocardial infarction, cardiac deaths and total deaths during the study period.

RESULTS: A total of 11 RCT’s with a total of 12644 patients were included in the meta-analysis, with 6598 patients in BD-DES vs 6046 patients in second generation PP-DES. The mean follow up period was 16 mo. Pooled analysis showed non-inferiority of BD-DES, comparing events of stent thrombosis (OR = 1.42, 95%CI: 0.79-2.52, P = 0.24), target lesion revascularization (OR = 0.99, 95%CI: 0.84-1.17, P = 0.92), myocardial infarction (OR = 1.06, 95%CI: 0.86-1.29, P = 0.92), cardiac deaths (OR = 1.07, 95%CI 0.82-1.41, P = 0.94) and total deaths (OR = 0.96, 95%CI: 0.80-1.17, P = 0.71).

CONCLUSION: BD-DES, when compared to second generation PP-DES, showed no significant advantage and the outcomes were comparable between both the groups.

Efficacy and safety of a novel bioabsorbable polymer-coated, everolimus-eluting coronary stent: the EVOLVE II Randomized Trial

BACKGROUND

Drug eluting stents with durable polymers may be associated with hypersensitivity, delayed healing, and incomplete endothelialization, which may contribute to late/very late stent thrombosis and the need for prolonged dual antiplatelet therapy. Bioabsorbable polymers may facilitate stent healing, thus enhancing clinical safety. The SYNERGY stent is a thin-strut, platinum chromium metal alloy platform with an ultrathin bioabsorbable Poly(D,L-lactide-co-glycolide) abluminal everolimus-eluting polymer. We performed a multicenter, randomized controlled trial for regulatory approval to determine noninferiority of the SYNERGY stent to the durable polymer PROMUS Element Plus everolimus-eluting stent.

METHODS AND RESULTS

Patients (n=1684) scheduled to undergo percutaneous coronary intervention for non-ST-segment-elevation acute coronary syndrome or stable coronary artery disease were randomized to receive either the SYNERGY stent or the PROMUS Element Plus stent. The primary end point of 12-month target lesion failure was observed in 6.7% of SYNERGY and 6.5% PROMUS Element Plus treated subjects by intention-to-treat (P=0.83 for difference; P=0.0005 for noninferiority), and 6.4% in both the groups by per-protocol analysis (P=0.0003 for noninferiority). Clinically indicated revascularization of the target lesion or definite/probable stent thrombosis were observed in 2.6% versus 1.7% (P=0.21) and 0.4% versus 0.6% (P=0.50) of SYNERGY versus PROMUS Element Plus-treated subjects, respectively.

CONCLUSIONS

In this randomized trial, the SYNERGY bioabsorbable polymer everolimus-eluting stent was noninferior to the PROMUS Element Plus everolimus-eluting stent with respect to 1-year target lesion failure. These data support the relative safety and efficacy of SYNERGY in a broad range of patients undergoing percutaneous coronary intervention.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01665053.

The metamorphosis of vascular stents: passive structures to smart devices

The role of nanotechnology enabled techniques in the evolution of vascular stents.

[What is the place of bioresorbable vascular scaffolds in setting of ST-segment elevation myocardial infarction?]

A 50-year-old woman was admitted for an inferior ST-segment elevation myocardial infarction; immediate coronary angiogram revealed a subocclusive stenosis of the right coronary artery. After optimal antithrombotic treatment, the type of stent could be discussed. The latest generation of drug-eluting stents showed excellent efficacy and safety in the long-term but has limitations such as potential chronic inflammation of the arterial wall and no recovery of vasoactive function. Bioresorbable vascular scaffolds, with complete resorption within several months, may reduce these limitations. Implantation of bioresorbable scaffold in the context of myocardial infarction may be interesting. However, very few studies are currently available in this setting. Preliminary results and perspectives are presented in this review.

Initial Experience With the Absorb Bioresorbable Vascular Scaffold Below the Knee

Purpose: To investigate a new bioresorbable vascular scaffold for the treatment of focal tibial and distal popliteal lesions. Methods: Tibial and distal popliteal angioplasty was performed in 15 limbs of 14 patients (9 men; median age 82 years) with critical limb ischemia (CLI, n=7) or severe claudication. The 18 lesions (mean length 22.2±14.0 mm) were implanted with 22 everolimus-eluting bioresorbable scaffolds (Absorb). Clinical and ultrasound follow-up was performed at 1, 3, 6, and 12 months to detect restenosis and evaluate safety, midterm restenosis rate, and clinical improvement. Results: Immediate technical success was 100%, although a single limb suffered 2 scaffold thromboses on the first day; it was salvaged with repeat endovascular intervention. All patients were available for surveillance examinations during a follow-up of 6.1±3.9 months; no patient died. Of the 15 limbs in the analysis, clinical improvement was present in 12 (4 of 7 CLI patients); there was no amputation, bypass surgery, or evidence of binary restenosis on follow-up sonographic examination. Conclusion: Midterm follow-up for this small pilot sample demonstrates acceptable safety and patency results, together with freedom from all major adverse limb events, using the Absorb bioresorbable vascular scaffold below the knee.

Clinical performance of biodegradable versus permanent polymer drug-eluting stents: A meta-analysis of randomized clinical trials at long-term follow-up

Several types of biodegradable polymer drug-eluting stents (BPDES) have been used for percutaneous transluminal angioplasty; however, the safety and efficiency of these BPDES have not been fully evaluated. A meta-analysis was, therefore, conducted to compare the clinical performance of BPDES with that of permanent polymer drug-eluting stents (PPDES) in unselected patients with coronary stenosis. PubMed, Web of Science, Medline and The Cochrane Library were searched for randomized clinical trials (RCTs) from January 2005 to January 2014. Trials that compared BPDES with PPDES in patients with coronary stenosis were considered. Twelve RCTs with a total of 15,938 patients with coronary stenosis were included in this meta-analysis. No significant difference was found between the two arms in the incidence of major adverse cardiac events (MACE) and definite or probable stent thrombosis (DpST) at the one-year follow-up (P>0.10). The use of BPDES, however, showed a tendency towards a lower risk of MACE (P=0.09) and a beneficial effect by reducing DpST episodes (P=0.04) at long-term follow-up, particularly when compared with the incidence of DpST at the one-year follow-up. BPDES also tended to be associated with a decreased late lumen loss in patients with coronary stenosis [instrumental variable =−0.04; 95% confidence interval =−0.08–0.00; P=0.05). In conclusion, the one-year outcomes following drug-eluting stent implantation showed BPDES were noninferior to PPDES in unselected patients with coronary stenosis. Long-term clinical outcomes, however, indicated that BPDES appeared to a present a lower risk of MACE and DpST.

Echogenicity as a surrogate for bioresorbable everolimus-eluting scaffold degradation: analysis at 1-, 3-, 6-, 12- 18, 24-, 30-, 36- and 42-month follow-up in a porcine model

The objective of the study is to validate intravascular quantitative echogenicity as a surrogate for molecular weight assessment of poly-l-lactide-acid (PLLA) bioresorbable scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California). We analyzed at 9 time points (from 1- to 42-month follow-up) a population of 40 pigs that received 97 Absorb scaffolds. The treated regions were analyzed by echogenicity using adventitia as reference, and were categorized as more (hyperechogenic or upperechogenic) or less bright (hypoechogenic) than the reference. The volumes of echogenicity categories were correlated with the measurements of molecular weight (Mw) by gel permeation chromatography. Scaffold struts appeared as high echogenic structures. The quantification of grey level intensity in the scaffold-vessel compartment had strong correlation with the scaffold Mw: hyperechogenicity (correlation coefficient = 0.75; P < 0.01), upperechogenicity (correlation coefficient = 0.63; P < 0.01) and hyper + upperechogenicity (correlation coefficient = 0.78; P < 0.01). In the linear regression, the R² for high echogenicity and Mw was 0.57 for the combination of hyper and upper echogenicity. IVUS high intensity grey level quantification is correlated to Absorb BVS residual molecular weight and can be used as a surrogate for the monitoring of the degradation of semi-crystalline polymers scaffolds.

ST-segment elevation myocardial infarction – ideal scenario for bioresorbable vascular scaffold implantation?

Bioresorbable vascular scaffolds (BVS) represent a breakthrough technology for percutaneous coronary intervention (PCI). In this context, because of the unique properties of bioresorbable devices, ST-segment elevation myocardial infarction (STEMI) may represent the ideal scenario for BVS implantation. Consistently, 57% of physicians declare they currently use BVS in this group of patients. However, continuous and growing evidence on the good performance of these devices has been actually shown only in small studies with short- and mid-term follow-up. For these reasons, we need data from sufficiently large observational studies, with long-term follow-up, to confirm that BVS can deliver the same results as 2nd-generation drug-eluting stents when using an appropriate implantation technique. In this review, we discuss the potential advantages of BVS implantation in STEMI patients, together with the most recent evidence from clinical studies, highlighting safety and procedural concerns.

Bioresorbable scaffolds for percutaneous coronary interventions

Innovations in drug-eluting stents (DES) have substantially reduced rates of in-segment restenosis and early stent thrombosis, improving clinical outcomes following percutaneous coronary interventions (PCI). However a fixed metallic implant in a vessel wall with restored patency and residual disease remains a precipitating factor for sustained local inflammation, in-stent neo-atherosclerosis and impaired vasomotor function increasing the risk for late complications attributed to late or very late stent thrombosis and late target lesion revascularization (TLR) (late catch-up).

The quest for optimal coronary stenting continues by further innovations in stent design and by using biocompatible materials other than cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding, local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics have been recently developed. These devices have been utilized in selected clinical applications so far providing preliminary evidence of safety showing comparable performance with current generation drug-eluting stents (DES).

Herein we provide a comprehensive overview of the current status of these technologies, we elaborate on the potential benefits of transient coronary scaffolds over permanent stents in the context of vascular reparation therapy, and we further focus on the evolving challenges these devices have to overcome to compete with current generation DES. Condensed Abstract:: The quest for optimizing percutaneous coronary interventions continues by iterative innovations in device materials beyond cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding; local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics were recently developed. These devices have been utilized in selected clinical applications providing preliminary evidence of safety showing comparable intermediate term clinical outcomes with current generation drug-eluting stents.

Effect of the endothelial shear stress patterns on neointimal proliferation following drug-eluting bioresorbable vascular scaffold implantation: an optical coherence tomography study

OBJECTIVES

This study sought to investigate the effect of endothelial shear stress (ESS) on neointimal formation following an Absorb bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) implantation.

BACKGROUND

Cumulative evidence, derived from intravascular ultrasound-based studies, has demonstrated a strong association between local ESS patterns and neointimal formation in bare-metal stents, whereas in drug-eluting stents, there are contradictory data about the effect of ESS on the vessel wall healing process. The effect of ESS on neointimal development following a bioresorbable scaffold implantation remains unclear.

METHODS

Twelve patients with an obstructive lesion in a relatively straight arterial segment, who were treated with an Absorb BVS and had serial optical coherence tomographic examination at baseline and 1-year follow-up, were included in the current analysis. The optical coherence tomographic data acquired at follow-up were used to reconstruct the scaffolded segment. Blood flow simulation was performed on the luminal surface at baseline defined by the Absorb BVS struts, and the computed ESS was related to the neointima thickness measured at 1-year follow-up.

RESULTS

At baseline, the scaffolded segments were exposed to a predominantly low ESS environment (61% of the measured ESS was <1 Pa). At follow-up, the mean neointima thickness was 113 ± 45 μm, whereas the percentage scaffold volume obstruction was 13.1 ± 6.6%. A statistically significant inverse correlation was noted between baseline logarithmic transformed ESS and neointima thickness at 1-year follow-up in all studied segments (correlation coefficient range -0.140 to -0.662). Mixed linear regression analysis between baseline logarithmic transformed ESS and neointima thickness at follow-up yielded a slope of -31 μm/ln(Pa) and a y-intercept of 99 μm.

CONCLUSIONS

The hemodynamic microenvironment appears to regulate neointimal response following an Absorb BVS implantation. These findings underline the role of the ESS patterns on vessel wall healing and should be taken into consideration in the design of bioresorbable devices.

Adjusting a polymer formulation for an optimal bioresorbable stent: a 6-month follow-up study

AIMS

To assess the impact of the composition in L- and D- of lactic acid stereo copolymers without drug elution on the in situ behaviour of prototype stents in terms of biomechanics and biocompatibility.

METHODS AND RESULTS

PLA50, 75, and 92 stereo-copolymer stents (L/D lactic acid ratio from 1 to 11.5) were processed using the injection moulding facilities of Arterial Remodeling Technologies (Noisy le Roi, France). The resulting 3 mm outer diameter tubes having a diameter at the desired nominal size were laser-cut and crimped on regular angioplasty balloons and chemically sterilised prior to implantation in iliac rabbit arteries. Acute recoil was higher in PLA50 and PLA75 stent-treated arteries than in those with PLA92 stents (17.4 ± 11.4 vs. 13.5 ± 7.6 vs. 4.1 ± 3.8 %, respectively, p=0.001). At one month, in-stent area was higher in PLA92 than in PLA50 and PLA75 stented arteries (5.9 ± 0.6 vs. 1.6 ± 1.6 vs. 2.6 ± 3.2 mm², respectively, p<0.001). Re-endothelialisation was complete, and inflammation was mild around the struts, similar among the three stents. Late lumen loss and neointimal area were low and similar in PLA92 stent-treated arteries one and six months after angioplasty (0.2 ± 0.2 vs. 0.3 ± 0.2 mm, p=0.60; 0.5 ± 0.5 vs. 0.5 ± 0.8 mm², p=0.72, respectively). At six months, inflammation decreased compared to one-month follow-up (1.4 ± 0.5 vs. 0.6 ± 0.5, p=0.006).

CONCLUSIONS

A stereo-copolymer composition strongly influences biomechanical properties of PLA bioresorbable stents in agreement with what has been known for a long time from other applications, but not biocompatibility. PLA92 stents appeared as presenting acceptable acute deployment and 6-month favourable outcome in the rabbit model despite the absence of drugs.

Biodegradable versus durable polymer drug eluting stents in coronary artery disease: insights from a meta-analysis of 5,834 patients

BACKGROUND

Biodegradable polymer drug eluting stents (BP-DES) have been developed to overcome the limitations of first generation durable polymer DES (DP-DES) but the clinical results of different BP-DES are not consistent. We performed a meta-analysis to compare the outcomes of BP-DES and DP-DES in the treatment of coronary artery disease (CAD).

METHODS AND RESULTS

Online databases including MEDLINE were searched for studies comparing BP-DES and DP-DES for obstructive CAD that reported rates for overall mortality, myocardial infarction (MI), late stent thrombosis (LST), target lesion revascularization (TLR) and late lumen loss (LLL) with a follow-up of ≥ 6 months. Ten studies (5834 patients) with a 1-year median follow-up were included in the meta-analysis. When comparing patients treated with DP-DES and BP-DES those treated with BP-DES had lower LLL (in-stent: weighted mean difference (WMD) -0.10 mm, 95% CI = -0.17 to -0.03 mm, p = 0.004; in-segment: WMD -0.06 mm, 95% CI = -0.10 to -0.01 mm, p = 0.01) with lower TLR rates (OR 0.67, 95% CI = 0.47 to 0.98, p = 0.04). However, BP-DES did not improve mortality (OR 0.97, 95% CI = 0.73 to 1.29, p = 0.83), MI (OR 1.13, 95% CI = 0.87 to 1.46, p = 0.36) or LST rates (OR 0.64, 95% CI = 0.36 to 1.16, p = 0.14). A pre-specified subgroup analysis of Biolimus BP-DES confirmed significant LLL reduction without differences in other clinical endpoints. Meta-regression analysis demonstrated a strong significant inverse correlation between LLL and reference coronary diameter (p < 0.001).

CONCLUSIONS

Our present meta-analysis showed that BP-DES when compared with DP-DES significantly reduced LLL and TVR but without clear benefits on mortality, MI and LST rates. (Clinicaltrials.gov identifier: NCT01466634).

Clinical performance of drug-eluting stents with biodegradable polymeric coating: a meta-analysis and systematic review

AIMS

Different biodegradable-polymer drug-eluting stents have not yet been systematically analysed. We sought to; 1) evaluate the risk of target lesion revascularisation (TLR) and definite stent thrombosis (DST) among different groups of biodegradable-polymer (BioPol) DES, and 2) to compare them with permanent polymer (PermPol) DES.

METHODS AND RESULTS

We searched PubMed and relevant sources from January 2005 until October 2010. Inclusion criteria were (a) Implantation of a drug-eluting stent with biodegradable polymer; (b) available follow-up data for at least one of the clinical end-points (TLR/DST) at short term (30 days) and/or mid-term (one year). A total of 22 studies, including randomised and observational studies, with 8264 patients met the selection criteria; nine studies (2042 patients) in whom biodegradable-polymer sirolimus eluting stents (BioPol-SES) were implanted, eight studies (1731 patients) in whom biodegradable-polymer paclitaxel eluting stents (BioPol-PES) were implanted, and seven studies (4491 patients) in whom biodegradable-polymer biolimus-A9 eluting stents (BioPol-BES) were implanted. At 30 days, there was a higher risk of DST (p=0.04) and subsequently TLR (p=0.006) in the BioPol-BES compared to BioPol-SES, with no significant difference in the other stent comparisons. At 1-year, there was higher risk of TLR in the BioPol-PES (p=0.01), and the BioPol-SES (p=0.04) compared to BioPol-BES. One-year stent thrombosis was not statistically different between the studied groups (overall p=0.2). In another analysis comprising seven randomised trials comparing BioPol-DES (3778 patients) and PermPol-DES (3291 patients), the risks of TLR and stent thrombosis at 1-year were not significantly different (p=0.5 for both).

CONCLUSIONS

Performance of different BioPol-DES seems to vary from each other. The short- and mid-term success rates may not be superimposable. Furthermore, they may not be necessarily better than PermPol-DES.

Restenosis after PCI. Part 2: prevention and therapy

The techniques and materials used during percutaneous coronary intervention have advanced considerably over the past 3 decades, yet restenosis remains one of the major drawbacks of this procedure. Many innovative technologies, including drug-eluting stents, with or without specific polymers, and fully biodegradable stents have been and continue to be developed in the search for a safe and effective antirestenosis therapy. Remarkable advances in stent design and nanoparticle delivery systems ('nanovehicles') have already fueled revolutionary changes in the prevention and treatment of in-stent restenosis. In this Review we provide an overview of the latest innovations for optimizing outcomes of coronary stenting, and up-to-date information about prevention and treatment of in-stent restenosis.

Intracoronary optical coherence tomography and histology at 1 month and 2, 3, and 4 years after implantation of everolimus-eluting bioresorbable vascular scaffolds in a porcine coronary artery model: an attempt to decipher the human optical coherence tomography images in the ABSORB trial

BACKGROUND

With the use of optical coherence tomography (OCT), alterations of the reflectance characteristics of everolimus-eluting bioresorbable vascular scaffold (BVS) struts have been reported in humans. In the absence of histology, the interpretation of the appearances of the struts by OCT remains speculative. We therefore report OCT findings with corresponding histology in the porcine coronary artery model immediately after and at 28 days and 2, 3, and 4 years after BVS implantation.

METHODS AND RESULTS

Thirty-five polymeric BVS (3.0×12.0 mm) were singly implanted in the main coronary arteries of 17 pigs that underwent OCT and were then euthanized immediately (n=2), at 28 days (n=2), at 2 years (n=3), at 3 years (n=5), or at 4 years (n=5) after implantation. All BVS-implanted arteries in these animals were evaluated by histology except for 5 arteries examined at 2 years with gel permeation chromatography to assess the biodegradation of the polymeric device. Fourteen arteries with BVS from an additional 6 pigs were examined by gel permeation chromatography at 1 (n=1), 1.5 (n=2), and 3 (n=2) years. Corresponding OCT and histology images were selected with the distal and proximal radiopaque markers used as landmarks. At 28 days, by OCT, 82% of struts showed sharply defined, bright reflection borders, best described as a box-shaped appearance. Histologically, all struts appeared intact with no evidence of resorption. At 2 years, by OCT, 60±20 struts were discernible per BVS with 80.4% of the strut sites as a box-shaped appearance. Despite their defined appearance by OCT, by histology, these structures appeared to be composed of proteoglycan, with polymeric material being at such low level as to be no longer quantifiable by chromatography. At 3 years, by OCT, recognizable struts decreased to 28±9 struts per BVS: 43.7% showed dissolved black box; 34.8%, dissolved bright box; 16.1%, open box; and 5.4%, preserved box appearance. Histology shows that connective tissue cells within a proteoglycan-rich matrix replaced the areas previously occupied by the polymeric struts and coalesced into the arterial wall. At 4 years, by OCT, 10±6 struts were recognizable as either dissolved black or dissolved bright box. In histology, these struts are minimally discernible as foci of low-cellular-density connective tissue. Relative to the prediction of histological type by OCT appearance, the preserved box appearance of OCT corresponds well with 2-year histology (86.4%), whereas the dissolved bright and black box appearances correspond to 3-year histology (88.0% and 90.7%, respectively). Struts indiscernible by OCT correspond to the integrated strut footprints seen at 4 years (100%).

CONCLUSIONS

Struts that are still discernible by OCT at 2 years are compatible with largely bioresorbed struts, as demonstrated by histological and gel permeation chromatography analysis. At 3 and 4 years, both OCT and histology confirm complete integration of the struts into the arterial wall.