Histopathological comparison of biodegradable polymer and permanent polymer based sirolimus eluting stents in a porcine model of coronary stent implantation

The relation of polymer structure of stent used in patients with acute coronary syndrome revascularized by stent implantation with long-term cardiovascular events

INTRODUCTION

Drug-eluting stents (DES) have revolutionized percutaneous coronary intervention (PCI) by improving event-free survival compared to older stent designs. However, early-generation DES with polymer matrixes have raised concerns regarding late stent thrombosis due to delayed vascular healing. To address these issues, biologically bioabsorbable polymer drug-eluting stents (BP-DES) and polymer-free drug-eluting stents (PF-DES) have been developed.

AIM

The aim of the present study is to evaluate and compare the long-term effects of different stent platforms in patients with acute coronary syndrome (ACS) undergoing PCI.

MATERIAL AND METHODS

We conducted a retrospective, observational study involving 1192 ACS patients who underwent urgent PCI. Patients were treated with thin- strut DP-DES, ultra-thin strut BP-DES, or thin-strut PF-DES. The primary endpoint was a composite of cardiac death, target vessel myocardial infarction (TVMI), and clinically driven target lesion revascularization (CITLR) at 12 months and 4 years.

RESULTS

The baseline demographics and clinical characteristics of patients in the three stent subgroups were similar. No significant differences were observed in target lesion failure (TLF), cardiac mortality, TVMI, and stent thrombosis (ST) rates among the three subgroups at both 12 months and 4 years. However, beyond the first year, the rate of CITLR was significantly lower in the ultra-thin strut BP-DES subgroup compared to thin-strut DP-DES, suggesting potential long-term advantages of ultra-thin strut BP-DES. Additionally, both ultra-thin strut BP-DES and thin-strut PF-DES demonstrated lower ST rates after the first year compared to thin-strut DP-DES.

CONCLUSION

Our study highlights the potential advantages of ultra-thin strut BP-DES in reducing CITLR rates in the long term, and both ultra-thin strut BP-DES and thin-strut PF-DES demonstrate lower rates of ST beyond the first year compared to thin-strut DP-DES. However, no significant differences were observed in overall TLF, cardiac mortality and TVMI rates among the three stent subgroups at both 12 months and 4 years.

Long-term safety of ultrathin bioabsorbable-polymer sirolimus-eluting stents versus thin durable-polymer drug-eluting stents in acute coronary syndrome: A systematic review and meta-analysis

BACKGROUND

Because of the advancement of bioabsorbable polymers and thinner struts, bioabsorbable-polymer sirolimus-eluting stents (BP-SES) with ultrathin struts may be related to superior performance when compared to durable-polymer drug-eluting stents (DP-DES) with thin struts. Nonetheless, the long-term safety of ultrathin BP-SES in acute coronary syndrome (ACS) remains unknown.

METHODS

We sought to assess the long-term safety of ultrathin BP-SES in ACS patients, conducting a thorough meta-analysis of all relevant trials drawing a comparison between ultrathin BP-SES and contemporary thin DP-DES. Target lesion failure (TLF), which includes cardiac death (CD), target-vessel myocardial infarction (TV-MI), and clinically driven target lesion revascularization (CD-TLR) was considered the primary endpoint. Multiple databases comprising Embase, MEDLINE, Cochrane Library, and Pubmed were all thoroughly searched.

RESULTS

There were seven randomized controlled trials included in our study with 7522 randomized patients with ACS (BP-SES = 3888, DP-DES = 3634). TLF occurred in 371 (9.5% in BP-SES) and 393 (10.8% in DP-DES) patients, respectively, across a 40.7-month weighted mean follow-up, with no statistically significant group differences (risk ratio [RR]: 0.87; 95% confidence interval [CI]: 0.73-1.04; p = .12). Furthermore, no significant differences in cardiac death (RR: 0.96; 95% CI: 0.68-1.35; p = .81), TV-MI (RR: 0.63; 95% CI: 0.36-1.10; p = .10) and CD-TLR (RR: 0.77; 95% CI: 0.46-1.29; p = .32) were detected between two groups.

CONCLUSION

During a follow-up of 40.7 months, ultrathin BP-SES and thin DP-DES had a comparable risk of TLF and its individual components (CD, TV-MI, and CD-TLR), indicating that ultrathin BP-SES held at least the same safety and efficiency as thin DP-DES presented in patients with ACS.

Ultrathin bioresorbable polymer sirolimus-eluting stents in US patients undergoing coronary revascularization: 1-Year outcomes from the BIOFLOW VII trial

BACKGROUND

Ultrathin strut coronary drug-eluting stents (DES) have demonstrated improved safety and efficacy in large contemporary trials. The evaluation of an ultrathin strut DES in a post-market United States (US) patient population was undertaken.

OBJECTIVE

The purpose of this post-approval study is to confirm that the clinical performance of an ultrathin strut bioresorbable polymer sirolimus-eluting stent (BP SES) in clinical practice is similar to that observed with BP SES in the BIOFLOW V pivotal trial.

METHODS

BIOFLOW VII is a prospective, multicenter, single-arm US post-market approval study to confirm the clinical performance of BP SES in a real-world setting. The primary endpoint of 1-year target lesion failure (TLF) was compared with a performance goal of 6.9% based on an adapted BIOFLOW V trial BP SES TLF rate and TLF rates from other US market-released DES utilizing the Society for Cardiovascular Angiography and Interventions definition for peri-procedural myocardial infarction (MI). Subjects undergoing percutaneous coronary intervention with BP SES were consented within 24 h post-index procedure with planned follow-up through 5 years.

RESULTS

Among 556 enrolled patients, clinical demographics included: 34.7% female, 35.6% with diabetes mellitus, and 56.8% with acute coronary syndromes. The average stent length (mean ± standard deviation) was 20.2 ± 11.8 mm, and the mean number of stents per patient was 1.3 ± 0.6. Procedure success was 99.1% (551/556), and device success was 99.9% (689/690). Among 531 subjects included in the primary endpoint analysis, the 1-year rate of TLF rate was 1.7% (9/531), and the primary endpoint was met compared with the performance goal (p < 0.0001, 95% confidence interval: 0.69%, 3.43%). Rates of target vessel MI and clinically driven target lesion revascularization were 1.3% (7/531) and 0.9% (5/531), with no occurrence of cardiac death. Definite stent thrombosis was observed for two cases (0.4%; 2/556) with one acute (≤24 h) and one late (>30 days and ≤1 year) event.

CONCLUSION

In a post-approval study, 1-year clinical outcomes with BP SES were consistent with prior trials supporting the safety and effectiveness of ultrathin BP SES.

PRospective Observational Registry Evaluating the Safety and Effectivenessof Orsiro Stent in Chilean Patients - ROSES Registry

BACKGROUND

There is little information on the performance of the new generation of stents with bioabsorbable polymers in the Latin American population. This registry aimed to further validate the safety and efficacy of the Orsiro bioresorbable-polymer sirolimus-eluting stent (BPSES) in unselected patients undergoing percutaneous coronary intervention (PCI) in Chilean centers.

METHODS

We prospectively enrolled patients undergoing PCI with BPSES in 6 Chilean centers. The primary endpoint was defined as the composite of cardiac death, target vessel-related myocardial infarction (MI), and clinically driven target lesion revascularization at 1-year follow-up.

RESULTS

From April 2017 to February 2019, 520 patients were enrolled in the registry, more frequently male (74.6%), with a mean age of 62.7 ± 10.8 years and a high prevalence of diabetes (40.2%). The clinical presentation was stable angina in 41.1% (n = 214), acute MI in 52.5% (n = 167 [32.1%] ST-elevation MI and n = 106 [20.4%] non-ST-elevation MI), and unstable angina in 6.3% (n = 33). Of 610 treated lesions, 425 (69.7%) were American College of Cardiology/American Heart Association type B or C lesions. Device and procedural success were achieved in 99.4% and 98.7% of the patients, respectively. The primary endpoint of the study occurred in 4%, primarily driven by cardiac death.

CONCLUSIONS

The results of the ROSES multicenter registry indicated good clinical outcomes of BPSES Orsiro in all-comers Latin Americann patients undergoing PCI, despite the high-risk patients and treated lesions.

Progress in drug-delivery systems in cardiovascular applications: stents, balloons and nanoencapsulation

Drug-delivery systems in cardiovascular applications regularly include the use of drug-eluting stents and drug-coated balloons to ensure sufficient drug transfer and efficacy in the treatment of cardiovascular diseases. In addition to the delivery of antiproliferative drugs, the use of growth factors, genetic materials, hormones and signaling molecules has led to the development of different nanoencapsulation techniques for targeted drug delivery. The review will cover drug delivery and coating mechanisms in current drug-eluting stents and drug-coated balloons, novel innovations in drug-eluting stent technologies and drug encapsulation in nanocarriers for delivery in vascular diseases. Newer technologies and advances in nanoencapsulation techniques, such as the use of liposomes, nanogels and layer-by-layer coating to deliver therapeutics in the cardiovascular space, will be highlighted.

Differential Effects of Newer-Generation Ultrathin-Strut Versus Thicker-Strut Drug-Eluting Stents in Chronic and Acute Coronary Syndromes

OBJECTIVES

The authors sought to compare the differential effects of ultrathin-strut and thicker-strut drug-eluting stents (DES) in patients with chronic (CCS) versus acute (ACS) coronary syndromes.

BACKGROUND

Newest-generation ultrathin-strut DES reduce target lesion failure (TLF) compared with thicker-strut second-generation DES in patients undergoing percutaneous coronary intervention.

METHODS

PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials comparing newer-generation ultrathin-strut (<70 μm) versus thicker-strut (≥70 μm) DES. Patients were divided based on baseline clinical presentation (CCS versus ACS). The primary endpoint was TLF, a composite of cardiac death, target vessel myocardial infarction, or clinically indicated target lesion revascularization (TLR).

RESULTS

A total of 22,766 patients from 16 randomized controlled trials were included, of which 9 trials reported TLF rates in ACS patients. At a mean follow-up of 12.2 months, the risk of TLF was lower among patients treated with ultrathin-strut compared with thicker-strut DES (risk ratio [RR]: 0.85; 95% CI: 0.75-0.95; P = 0.006). The difference was driven by a lower risk of clinically-indicated TLR (RR: 0.75; 95% CI: 0.63-0.89; P < 0.001) among patients treated with ultrathin-strut DES. The treatment effect was consistent between patients presenting with CCS and ACS (relative RR: 0.97; 95% CI: 0.73-1.31; P for interaction = 0.854). In patients with ST-segment elevation myocardial infarction, TLF risk was lower among those treated with ultrathin- compared with thicker-strut DES (RR: 0.74; 95% CI: 0.54-0.99; P = 0.049).

CONCLUSIONS

Ultrathin-strut DES reduce the risk of TLF compared with thicker-strut second-generation DES in patients undergoing percutaneous coronary intervention, a difference caused by a lower risk of ischemia-driven TLR. The treatment effect was consistent among patients with CCS and ACS.

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.

Early Vascular Healing Following Bioresorbable-Polymer Sirolimus-Eluting Stent Placement Compared to That with Durable-Polymer Everolimus-Eluting Stent

A recent thinner strut drug-eluting stent might facilitate early strut coverage after its placement. We aimed to investigate early vascular healing responses after the placement of an ultrathin-strut bioresorbable-polymer sirolimus-eluting stent (BP-SES) compared to those with a durable-polymer everolimus-eluting stent (DP-EES) using optical coherence tomography (OCT) imaging.This study included 40 patients with chronic coronary syndrome (CCS) who underwent OCT-guided percutaneous coronary intervention (PCI). Twenty patients each received either BP-SES or DP-EES implantation. OCT was performed immediately after stent placement (baseline) and at 1-month follow-up.At one month, the percentage of uncovered struts reduced significantly in both the BP-SES (80.9 ± 10.3% to 2.9 ± 1.7%; P < 0.001) and DP-EES (81.9 ± 13.0% to 5.7 ± 1.8%; P < 0.001) groups, and the percentage was lower in the BP-SES group than in the DP-EES group (P < 0.001). In the BP-SES group, the percentage of malapposed struts also decreased significantly at 1 month (4.9 ± 3.7% to 2.6 ± 3.0%; P = 0.025), which was comparable to that of the DP-EES group (2.5 ± 2.2%; P = 0.860). The optimal cut-off value of the distance between the strut and vessel surface immediately after the placement to predict resolved malapposed struts was ≤ 160 μm for BP-SES and ≤ 190 μm for DP-EES.Compared to DP-EES, ultrathin-strut BP-SES demonstrated favorable vascular responses at one month, with a lower rate of uncovered struts and a comparable rate of malapposed struts.

Five-year outcomes with biodegradable polymer sirolimus-eluting stents versus durable polymer everolimus-eluting stents in patients with acute coronary syndrome: A subgroup analysis of the BIOSCIENCE trial

BACKGROUND

Thin-strut biodegradable polymer sirolimus-eluting stents (BP-SES) have been shown to reduce target lesion failure (TLF) at one-year follow-up compared with durable polymer everolimus-eluting stents (DP-EES) among patients with acute coronary syndrome (ACS). The long-term clinical benefits of thin-strut BP-SES over DP-EES in ACS patients after complete degradation of the polymer coating remain uncertain.

METHODS

We performed a post-hoc subgroup analysis of ACS patients included into the BIOSCIENCE randomized trial (NCT01443104). The primary endpoint was target lesion failure (TLF), a composite of cardiac death, target-vessel myocardial infarction or clinically indicated target lesion revascularization, at 5 years.

RESULTS

Among 2119 patients enrolled between March 2012 and May 2013, 1131 (53%) presented with ACS. The 5-year cumulative incidence of TLF was significantly lower in patients with ACS compared to chronic coronary syndrome [16.5% vs. 22.9%; rate ratio (RR), 0.69; 95% confidence interval (CI), 0.57-0.85; p < 0.001]. At 5 years, TLF occurred similarly in ACS patients treated with BP-SES and DP-EES (16.9% vs. 16.0%; RR, 1.04; 95% CI, 0.78-1.41; p = 0.78). The individual components of the primary endpoint did not differ between ACS patients treated with BP-SES or DP-EES at 5 years. Overall, there was no interaction between clinical presentation and treatment effect.

CONCLUSIONS

In a subgroup analysis of the BIOSCIENCE trial, we found no difference in long-term outcomes between ACS patients treated with BP-SES or DP-EES at 5 years.

Safety of 3-Month Dual Antiplatelet Therapy After Implantation of Ultrathin Sirolimus-Eluting Stents With Biodegradable Polymer (Orsiro): Results From the SMART-CHOICE Trial

Background

This study sought to investigate the safety of 3‐month dual antiplatelet therapy (DAPT) in patients receiving ultrathin sirolimus‐eluting stents with biodegradable polymer (Orsiro).

Methods and Results

The SMART‐CHOICE (Smart Angioplasty Research Team: Comparison Between P2Y12 Antagonist Monotherapy vs Dual Anti‐ platelet Therapy in Patients Undergoing Implantation of Coronary Drug‐Eluting Stents) randomized trial compared 3‐month DAPT followed by P2Y12 inhibitor monotherapy with 12‐month DAPT in 2993 patients undergoing percutaneous coronary intervention. The present analysis was a prespecified subgroup analysis for patients receiving Orsiro stents. As a post hoc analysis, comparisons between Orsiro and everolimus‐eluting stents were also done among patients receiving 3‐month DAPT. Of 972 patients receiving Orsiro stents, 481 patients were randomly assigned to 3‐month DAPT and 491 to 12‐month DAPT. At 12 months, the target vessel failure, defined as a composite of cardiac death, target vessel–related myocardial infarction, or target vessel revascularization, occurred in 8 patients (1.7%) in the 3‐month DAPT group and in 14 patients (2.9%) in the 12‐month DAPT group (hazard ratio [HR], 0.58; 95% CI, 0.24–1.39; P=0.22). In whole population who were randomly assigned to receive 3‐month DAPT (n=1495), there was no significant difference in the target vessel failure between the Orsiro group and the everolimus‐eluting stent group (n=1014) (1.7% versus 1.8%; HR, 0.96; 95% CI, 0.41–2.22; P=0.92).

Conclusions

In patients receiving Orsiro stents, clinical outcomes at 1 year were similar between the 3‐month DAPT followed by P2Y12 inhibitor monotherapy and 12‐month DAPT strategies. With 3‐month DAPT, there was no significant difference in target vessel failure between Orsiro and everolimus‐eluting stents.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02079194.

Three-year clinical outcome of biodegradable hybrid polymer Orsiro sirolimus-eluting stent and the durable biocompatible polymer Resolute Integrity zotarolimus-eluting stent: A randomized controlled trial

AIMS

We compared long-term clinical outcomes between patients treated with Orsiro sirolimus-eluting stent (O-SES) and those treated with durable biocompatible polymer Resolute Integrity zotarolimus-eluting stent (R-ZES).

METHODS AND RESULTS

The ORIENT trial was a randomized controlled noninferiority trial to compare angiographic outcomes between O-SES and R-ZES. We performed a post hoc analysis of 3-year clinical outcomes and included 372 patients who were prospectively enrolled and randomly assigned to O-SES (n = 250) and R-ZES (n = 122) groups in a 2:1 ratio. The primary endpoint was target lesion failure defined as a composite of cardiac death, nonfatal myocardial infarction, and target lesion revascularization. At 3 years, target lesion failure occurred in 4.7% and 7.8% of O-SES and R-ZES groups, respectively (hazard ratio, 0.58; 95% confidence intervals, 0.24-1.41; p = .232 by log-rank test). Secondary endpoints including cardiac death, myocardial infarction, and target lesion revascularization showed no significant differences between the groups. Stent thrombosis occurred in two patients in R-ZES group (0.0% vs. 1.6%, p = .040).

CONCLUSION

This study confirms long-term safety and efficacy of the two stents. We found a trend for lower target lesion failure with O-SES compared to R-ZES, although statistically insignificant.

Percutaneous complete revascularization strategies using sirolimus-eluting biodegradable polymer-coated stents in patients presenting with acute coronary syndrome and multivessel disease: Rationale and design of the BIOVASC trial

BACKGROUND

Complete revascularization in patients with an acute coronary syndrome and multivessel disease is superior compared to culprit-only treatment. However, it is unknown whether direct complete or staged complete revascularization should be pursued.

METHODS

The BIOVASC study is an investigator-initiated, prospective, multicenter, randomized, 2-arm, international, open-label, noninferiority trial. We will randomize 1,525 patients 1:1 to immediate complete revascularization (experimental arm) or culprit-only plus staged complete revascularization (control arm). Patients will be enrolled in approximately 30 sites in Belgium, Italy, the Netherlands, and Spain. The primary end point is a composite of all-cause mortality, nonfatal myocardial infarction, any unplanned ischemia-driven revascularization (excluding staged procedures in the control arm at the predetermined time), and cerebrovascular events (MACCE) at 1 year post index procedure.

CONCLUSIONS

The BIOVASC study aims to further refine the treatment algorithm for acute coronary syndrome patients with multivessel disease in terms of optimal timing for complete revascularization (Clinicaltrials.gov NCT03621501).

A Review of the Ultrathin Orsiro Biodegradable Polymer Drug-eluting Stent in the Treatment of Coronary Artery Disease

Drug-eluting stents (DES) have revolutionised the treatment of coronary artery disease (CAD) in patients undergoing percutaneous coronary intervention. In recent years, there has been a focus on a new generation of DES, such as biodegradable polymer DES (BP-DES). This novel stent platform was developed with the hope of eliminating the risk of very late stent thrombosis associated with the current gold-standard durable polymer DES (DP-DES). Ultrathin Orsiro BP-DES (Biotronik, Bülach, Switzerland) are based on a cobalt-chromium stent platform that is coated with a bioresorbable polymer coating containing sirolimus. These devices have one of the thinnest struts available in the current market and have the theoretical benefit of reducing a chronic inflammatory response in the vessel wall. In 2019, the United States Food and Drug Administration (FDA) approved the use of Orsiro BP-DES in patients with CAD based on promising results in recent landmark trials, such as BIOFLOW V and BIOSTEMI. The aim of the present review article was to discuss the history of stent technology and the continued opportunities for improvements, focusing on the potential benefits of Orsiro BP-DES.

Assessment of the healing process after percutaneous implantation of a cardiovascular device: a systematic review

The healing process, occurring after intra-cardiac and intra-vascular device implantation, starts with fibrin condensation and attraction of inflammatory cells, followed by the formation of fibrous tissue that slowly covers the device. The duration of this process is variable and may be incomplete, which can lead to thrombus formation, dislodgement of the device or stenosis. To better understand this process and the neotissue formation, animal models were developed: small (rats and rabbits) and large (sheep, pigs, dogs and baboons) animal models for intra-vascular device implantation; sheep and pigs for intra-cardiac device implantation. After intra-vascular and intra-cardiac device implantation in these animal models, in vitro techniques, i.e. histology, which is the gold standard and scanning electron microscopy, were used to assess the device coverage, characterize the cell constitution and detect complications such as thrombosis. In humans, optical coherence tomography and intra-vascular ultrasounds are both invasive modalities used after stent implantation to assess the structure of the vessels, atheroma plaque and complications. Non-invasive techniques (computed tomography and magnetic resonance imaging) are in development in humans and animal models for tissue characterization (fibrosis), device remodeling evaluation and device implantation complications (thrombosis and stenosis). This review aims to (1) present the experimental models used to study this process on cardiac devices; (2) focus on the in vitro techniques and invasive modalities used currently in humans for intra-vascular and intra-cardiac devices and (3) assess the future developments of non-invasive techniques in animal models and humans for intra-cardiac devices.

Procedural advantages of a novel coronary stent design with ultra-thin struts and bioabsorbable abluminal polymer coating in an all-comers registry

Introduction

The implications of novel drug-eluting stent (DES) design modifications including ultra-thin struts and new concepts of polymer coating for procedural efficacy are still unknown.

Aim

To evaluate procedural efficacy and short-term safety of a novel DES design.

Material and methods

In this all-comers registry, 407 consecutive patients were enrolled upon undergoing percutaneous coronary interventions (PCI) with the thin-strut bioabsorbable abluminal polymer-coated SYNERGY stent. These patients were then compared with the previous 407 patients undergoing PCI performed by the same interventionalists using currently established second-generation DES (Promus Element plus, Xience prime, Resolute Integrity). Several clinical and procedural data were compared, and the coronary artery complexity was assessed by the American College of Cardiology/American Heart Association classification and SYNTAX Score.

Results

The study population consisted of 814 patients. A total of 859 Synergy stents were deployed in 480 target vessels in the Synergy group (n = 407), and 904 stents in 469 vessels in the second-generation DES group (n = 407). Coincidentally, target lesions in the Synergy group (A 2.7%, B1 13.8%, B2 38.6%, C 45.0%) were more complex (p < 0.01) than those in the second-generation DES group (A 4.9%, B1 18.7%, B2 42.3%, C 34.2%). In cases with severe lesions (B2/C), the median contrast agent amount and fluoroscopy time were significantly lower in the Synergy group, indicating improved deliverability (110 ml vs. 150 ml; p < 0.01 and 7.2 min vs. 9.1 min; p = 0.01). Rates of in-hospital major adverse cardiovascular events were comparable between the two groups.

Conclusions

In an all-comers, real-world PCI population, novel stent design modifications including ultra-thin struts and abluminal bioabsorbable polymer coating are associated with improved procedural performance.

Ultrathin, bioresorbable polymer sirolimus-eluting stents versus thin, durable polymer everolimus-eluting stents in patients undergoing coronary revascularisation (BIOFLOW V): a randomised trial

BACKGROUND

The development of coronary drug-eluting stents has included use of new metal alloys, changes in stent architecture, and use of bioresorbable polymers. Whether these advancements improve clinical safety and efficacy has not been shown in previous randomised trials. We aimed to examine the clinical outcomes of a bioresorbable polymer sirolimus-eluting stent compared with a durable polymer everolimus-eluting stent in a broad patient population undergoing percutaneous coronary intervention.

METHODS

BIOFLOW V was an international, randomised trial done in patients undergoing elective and urgent percutaneous coronary intervention in 90 hospitals in 13 countries (Australia, Belgium, Canada, Denmark, Germany, Hungary, Israel, the Netherlands, New Zealand, South Korea, Spain, Switzerland, and the USA). Eligible patients were those aged 18 years or older with ischaemic heart disease undergoing planned stent implantation in de-novo, native coronary lesions. Patients were randomly assigned (2:1) to either an ultrathin strut (60 μm) bioresorbable polymer sirolimus-eluting stent or to a durable polymer everolimus-eluting stent. Randomisation was via a central web-based data capture system (mixed blocks of 3 and 6), and stratified by study site. The primary endpoint was 12-month target lesion failure. The primary non-inferiority comparison combined these data from two additional randomised trials of bioresorbable polymer sirolimus-eluting stent and durable polymer everolimus-eluting stent with Bayesian methods. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT02389946.

FINDINGS

Between May 8, 2015, and March 31, 2016, 4772 patients were recruited into the study. 1334 patients met inclusion criteria and were randomly assigned to treatment with bioresorbable polymer sirolimus-eluting stents (n=884) or durable polymer everolimus-eluting stents (n=450). 52 (6%) of 883 patients in the bioresorbable polymer sirolimus-eluting stent group and 41 (10%) of 427 patients in the durable polymer everolimus-eluting stent group met the 12-month primary endpoint of target lesion failure (95% CI -6·84 to -0·29, p=0·0399), with differences in target vessel myocardial infarction (39 [5%] of 831 patients vs 35 [8%] of 424 patients, p=0·0155). The posterior probability that the bioresorbable polymer sirolimus-eluting stent is non-inferior to the durable polymer everolimus-eluting stent was 100% (Bayesian analysis, difference in target lesion failure frequency -2·6% [95% credible interval -5·5 to 0·1], non-inferiority margin 3·85%, n=2208).

INTERPRETATION

The outperformance of the ultrathin, bioresorbable polymer sirolimus-eluting stent over the durable polymer everolimus-eluting stent in a complex patient population undergoing percutaneous coronary intervention suggests a new direction in improving next generation drug-eluting stent technology.

FUNDING

BIOTRONIK.

Randomized Multicenter Trial Investigating Angiographic Outcomes of Hybrid Sirolimus-Eluting Stents With Biodegradable Polymer Compared With Everolimus-Eluting Stents With Durable Polymer in Chronic Total Occlusions: The PRISON IV Trial

OBJECTIVES

The aim of this study was to investigate the efficacy and safety of the hybrid ultrathin-strut sirolimus-eluting stent (SES) with biodegradable polymer compared with the thin-strut everolimus-eluting stent (EES) with durable polymer in successfully recanalized chronic total occlusions (CTOs).

BACKGROUND

The introduction of drug-eluting stents revolutionized the treatment of CTOs. However, limited data are available on new-generation drug-eluting stents with biodegradable polymer in CTOs.

METHODS

In this multicenter trial, patients were randomized, after successful CTO recanalization, to either SES or EES. The primary noninferiority endpoint was in-segment late lumen loss (noninferiority margin 0.2 mm). Secondary endpoints included in-stent late lumen loss and clinical endpoints.

RESULTS

Overall, 330 patients were included. At 9 months, angiography was available in 281 patients (85%). Duration of occlusion ≥3 months was 92.5%, with mean stent length of 52.4 ± 28.1 mm versus 52.3 ± 26.5 mm in the SES and EES groups. The primary noninferiority endpoint, in-segment late lumen loss, was not met for SES versus EES (0.13 ± 0.63 mm vs. 0.02 ± 0.47 mm; p = 0.08, 2-sided; difference 0.11 mm; 95% confidence interval: -0.01 to 0.25 mm; p_{noninferiority} = 0.11, 1-sided). In-stent late lumen loss was comparable between SES and EES (0.12 ± 0.59 mm vs. 0.07 ± 0.46 mm; p = 0.52). The incidence of in-stent and in-segment binary restenosis was significantly higher with SES compared with EES (8.0% vs. 2.1%; p = 0.028), with comparable rates of reocclusions (2.2% vs. 1.4%; p = 0.68). Clinically indicated target lesion and target vessel revascularization (9.2% vs. 4.0% [p = 0.08] and 9.2% vs. 6.0% [p = 0.33]), target vessel failure (9.9% vs. 6.6%; p = 0.35), and definite or probable stent thrombosis (0.7% vs. 0.7%; p = 1.00) were comparable between the SES and EES groups.

CONCLUSIONS

This randomized trial failed to show noninferiority of hybrid SES relative to EES in terms of in-segment late lumen loss in successfully recanalized CTOs. Furthermore, a statistically significantly higher rate of binary restenosis was found with SES.

Permanent and biodegradable polymer coatings in the absence of antiproliferative drugs in a porcine model of coronary artery stenting

AIMS

The purpose of the present study was to examine the comparative vascular healing response to stents coated with permanent or biodegradable polymer and uncoated stents in a porcine model of coronary artery stenting.

METHODS AND RESULTS

Juvenile pigs were randomly allocated to implantation of stents coated with permanent polymer (PP, methacrylate-based, n=10), biodegradable polymer (BP, poly-lactic acid-based, n=10) or bare metal control stents (n=10), in the absence of antiproliferative drugs. At 28 days, animals were sacrificed and specimens prepared for histopathologic assessment. Endothelialisation was complete in all treatment groups. Vascular injury at 28 days was greater in PP stents as compared with uncoated stents (p=0.05) though not as compared with BP-coated stents (p=ns). PP stents showed increased inflammatory scores compared with BP-coated (p=0.03) and uncoated stents (p=0.02). There was also greater neointimal growth with PP-coated stents compared with uncoated stents (p=0.02).

CONCLUSIONS

In the absence of antiproliferative drugs, stents coated with methacrylate-based PP, but not with poly-lactic acid-based BP, provoked significant vessel wall inflammatory reactions resulting in greater vascular injury and increased neointimal growth compared with uncoated stents. Biodegradable polymer coatings may be considered preferable to facilitate drug elution with minimal vessel wall toxicity.

Current State of Bioabsorbable Polymer-Coated Drug-Eluting Stents

Drug-eluting stents (DES) have been shown to significantly reduce clinical and angiographic restenosis compared to bare metal stents (BMS). The polymer coatings on DES elute antiproliferative drugs to inhibit intimal proliferation and prevent restenosis after stent implantation. Permanent polymers which do not degrade in vivo may increase the likelihood of stent-related delayed arterial healing or polymer hypersensitivity. In turn, these limitations may contribute to an increased risk of late clinical events. Intuitively, a polymer which degrades after completion of drug release, leaving an inert metal scaffold in place, may improve arterial healing by removing a chronic source of inflammation, neoatherosclerosis, and/or late thrombosis. In this way, a biodegradable polymer may reduce late ischemic events. Additionally, improved healing after stent implantation could reduce the requirement for long-term dual antiplatelet therapy and the associated risk of bleeding and cost. This review will focus on bioabsorbable polymer-coated DES currently being evaluated in clinical trials.

Comparison of a novel biodegradable polymer sirolimus-eluting stent with a durable polymer everolimus-eluting stent: results of the randomized BIOFLOW-II trial

BACKGROUND

Biodegradable polymers for release of antiproliferative drugs from drug-eluting stents aim to improve vascular healing. We assessed noninferiority of a novel ultrathin strut drug-eluting stent releasing sirolimus from a biodegradable polymer (Orsiro, O-SES) compared with the durable polymer Xience Prime everolimus-eluting stent (X-EES) in terms of the primary end point in-stent late lumen loss at 9 months.

METHODS AND RESULTS

A total of 452 patients were randomly assigned 2:1 to treatment with O-SES (298 patients, 332 lesions) or X-EES (154 patients, 173 lesions) in a multicenter, noninferiority trial. The primary end point was in-stent late loss at 9 months. O-SES was noninferior to X-EES for the primary end point (0.10±0.32 versus 0.11±0.29 mm; difference=0.00063 mm; 95% confidence interval, -0.06 to 0.07; Pnoninferiority<0.0001). Clinical outcome showed similar rates of target-lesion failure at 1 year (O-SES 6.5% versus X-EES 8.0%; hazard ratio=0.82; 95% confidence interval, 0.40-1.68; log-rank test: P=0.58) without cases of stent thrombosis. A subgroup of patients (n=55) underwent serial optical coherence tomography at 9 months, which demonstrated similar neointimal thickness among lesions allocated to O-SES and X-EES (0.10±0.04 mm versus 0.11±0.04 mm; -0.01 [-0.04, -0.01]; P=0.37). Another subgroup of patients (n=56) underwent serial intravascular ultrasound at baseline and 9 months indicating a potential difference in neointimal area at follow-up (O-SES, 0.16±0.33 mm(2) versus X-EES, 0.43±0.56 mm(2); P=0.04).

CONCLUSIONS

Compared with durable polymer X-EES, novel biodegradable polymer-based O-SES was found noninferior for the primary end point in-stent late lumen loss at 9 months. Clinical event rates were comparable without cases of stent thrombosis throughout 1 year of follow-up.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01356888.

Impact of stent strut design in metallic stents and biodegradable scaffolds

Advances in the understanding of healing mechanisms after stent implantation have led to the recognition of stent strut thickness as an essential factor affecting re-endothelialization and overall long term vessel healing response after Percutaneous Coronary Interventions (PCI). Emergence of Drug-eluting stents (DESs) with anti-proliferative coating has contributed to reducing the incidence of restenosis and Target Lesion Revascularization (TVR), while progress and innovations in stent materials have in the meantime facilitated the design of newer platforms with more conformability and thinner struts, producing lesser injury and improving integration into the vessel wall. Recent advances in biodegradable metal and polymer materials now also allow for the design of fully biodegradable platforms, which are aimed at scaffolding the vessel only temporarily to prevent recoil and constrictive remodeling of the vessel during the initial period required, and are then progressively resorbed thereby avoiding the drawback of leaving an unnecessary implant permanently in the vessel. The aim of this article is to review recent evolution in stent material and stent strut design while understanding their impact on PCI outcomes. The article describes the different metallic alloys and biodegradable material properties and how these have impacted the evolution of stent strut thickness and ultimately outcomes in patients.

Comparison of 3 biodegradable polymer and durable polymer-based drug-eluting stents in all-comers (BIO-RESORT): rationale and study design of the randomized TWENTE III multicenter trial

AIM

To evaluate the safety and efficacy of 2 novel drug-eluting stents (DES) with biodegradable polymer-based coatings versus a durable coating DES.

METHODS AND RESULTS

BIO-RESORT is an investigator-initiated, prospective, patient-blinded, randomized multicenter trial in 3540 Dutch all-comers with various clinical syndromes, requiring percutaneous coronary interventions (PCI) with DES implantation. Randomization (stratified for diabetes mellitus) is being performed in a 1:1:1 ratio between ORSIRO sirolimus-eluting stent with circumferential biodegradable coating, SYNERGY everolimus-eluting stent with abluminal biodegradable coating, and RESOLUTE INTEGRITY zotarolimus-eluting stent with durable coating. The primary endpoint is the incidence of the composite endpoint target vessel failure at 1 year, consisting of cardiac death, target vessel-related myocardial infarction, or clinically driven target vessel revascularization. Power calculation assumes a target vessel failure rate of 8.5% with a 3.5% non-inferiority margin, giving the study a power of 85% (α level .025 adjusted for multiple testing). The impact of diabetes mellitus on post-PCI outcome will be evaluated. The first patient was enrolled on December 21, 2012.

CONCLUSIONS

BIO-RESORT is a large, prospective, randomized, multicenter trial with three arms, comparing two DES with biodegradable coatings versus a reference DES with a durable coating in 3540 all-comers. The trial will provide novel insights into the clinical outcome of modern DES and will address the impact of known and so far undetected diabetes mellitus on post-PCI outcome.

Dual drug-eluting stents coated with multilayers of hydrophobic heparin and sirolimus

Polymer coatings for stents are considered one of the key factors that lead to adverse cardiac events after coronary arterial stenting. This study presents a dual drug-eluting stent (DES) that is coated with multilayers of Duraflo heparin and sirolimus but containing no other organic polymers. The hydrophobic Duraflo heparin coating was used to improve the hemocompatibility of the stent and serve as a drug reservoir for the controlled release of sirolimus, thus avoiding inflammatory reactions induced by the conventional polymers. The Duraflo heparin and sirolimus were coated layer-by-layer onto the stent surface using a homemade spray-coating device. The drug loading amount can be easily controlled by adjusting the numbers of layers applied and the concentration of the drug solution, indicating the developed coating process is reproducible and well-controlled. After balloon expansion, the coating did not crack or peel off, which demonstrates that the sirolimus/Duraflo heparin coating layers tightly adhere to the stent surface. The activated partial thromboplastin time (APTT) assay showed that the Duraflo heparin coating significantly prolonged the APTT from 27.3 ± 0.3 s to 69.7 ± 6.2 s, demonstrating the anticoagulant ability of the coated stents. The dual DES exhibited a nearly linear sustained-release profile of Duraflo heparin and an initial burst release followed by a slow release of sirolimus. Less than 15% of heparin was released from the DES within 14 days, indicating the stent can maintain its antithrombotic surface for a long time. Because of the layer-by-layer structure, the most outer layer of Duraflo heparin coating may act as a diffusion barrier to retard sirolimus release from the stent. These results confirm that the dual DESs enable simultaneous delivery of antithrombotic and antiproliferative drugs and have potential for the treatment of coronary artery disease.

Inhibition of Orai1-mediated Ca(2+) entry is a key mechanism of the antiproliferative action of sirolimus in human arterial smooth muscle

Sirolimus (rapamycin) is used in drug-eluting stent strategies and proved clearly superior in this application compared with other immunomodulators such as pimecrolimus. The molecular basis of this action of sirolimus in the vascular system is still incompletely understood. Measurements of cell proliferation in human coronary artery smooth muscle cells (hCASM) demonstrated a higher antiproliferative activity of sirolimus compared with pimecrolimus. Although sirolimus lacks inhibitory effects on calcineurin, nuclear factor of activated T-cell activation in hCASM was suppressed to a similar extent by both drugs at 10 μM. Sirolimus, but not pimecrolimus, inhibited agonist-induced and store-operated Ca(2+) entry as well as cAMP response element binding protein (CREB) phosphorylation in human arterial smooth muscle, suggesting the existence of an as-yet unrecognized inhibitory effect of sirolimus on Ca(2+) signaling and Ca(2+)-dependent gene transcription. Electrophysiological experiments revealed that only sirolimus but not pimecrolimus significantly blocked the classical stromal interaction molecule/Orai-mediated, store-operated Ca(2+) current reconstituted in human embryonic kidney cells (HEK293). A link between Orai function and proliferation was confirmed by dominant-negative knockout of Orai in hCASM. Analysis of the effects of sirolimus on cell proliferation and CREB activation in an in vitro model of arterial intervention using human aorta corroborated the ability of sirolimus to suppress stent implantation-induced CREB activation in human arteries. We suggest inhibition of store-operated Ca(2+) entry based on Orai channels and the resulting suppression of Ca(2+) transcription coupling as a key mechanism underlying the antiproliferative activity of sirolimus in human arteries. This mechanism of action is specific for sirolimus and not a general feature of drugs interacting with FK506-binding proteins.

Dexamethasone-eluting vascular stents

Percutaneous transluminal angioplasty (PTA) with stenting is widely used in the treatment of vascular disorders, but restenosis remains a significant problem. Drug-eluting stents (DES) have been developed as an attempt to reduce the intimal response leading to restenosis. Drugs used in DES include mainly immunosuppressive and anti-proliferative compounds. Glucocorticoids are also an interesting possibility for those purposes because they have anti-proliferative effects in vascular smooth muscle cells and down-regulate the production of cytokines and growth factors driving inflammation and fibrosis. In this MiniReview, feasibility and safety of drug-eluting metal and biodegradable vascular stents are discussed with special emphasis on dexamethasone-eluting stents.