Safety and Efficacy of BioMime Sirolimus-Eluting Stent System in All-Comers Real-World Population With Coronary Artery Stenosis: MILES Global Registry

Background

This study evaluated the safety and efficacy of BioMime sirolimus-eluting stent (SES) system, with an ultra-low strut thickness (65 µm), in real-world all-comers population with coronary artery stenosis (CAD).

Methods

This was a post-marketing, multicenter, single-arm, observational clinical registry among patients undergoing intervention for CAD. Patients were clinically followed up at 1, 9, 12, and 24 months after the index percutaneous coronary intervention. Four major indications, namely long stents of > 30 mm, stents with diameters of 4 and 4.5 mm, bifurcation subgroup, and chronic total occlusion (CTO) were evaluated as pre-specified subsets.

Results

A total of 771 patients (1,079 treated lesions) from 23 sites were included in this study. The mean length and diameter of the implanted stents were 25.57 ± 9.35 mm and 3.00 ± 0.44 mm, respectively. The mean minimum lumen diameter before and after the procedure was 1.00 ± 1.69 mm and 2.96 ± 1.35 mm, respectively. The cumulative rates of major adverse cardiovascular events (MACEs) and stent thrombosis (ST) at 1, 9, 12, and 24 months were 1.05%, 3.13%, 4.04%, 5.64% and 0%, 0.13%, 0.28%, 0.28%, respectively. In a subset with > 30 mm long stents, the cumulative rate of MACEs was 0.4%, 4.6%, 5.12%, and 7.01% at 1, 9, 12, and 24 months, respectively. The corresponding rates of ST were 0%, 0.42%, 0.43%, and 0.44%, indicating constant rate of ST after 9 months. In a subset of 4 and 4.5 mm diameter stents, the cumulative rate of MACEs was high (0%, 6.25%, 6.25%, and 10.41%) at 1, 9, 12, and 24 months, respectively. However, there was no case of ST until 24 months. In patients with bifurcation lesions, the cumulative rates of MACEs and ST were 2.46%, 6.32%, 11.53%, 16.21% and 0%, 1.27%, 1.28%, 1.35% at 1, 9, 12, and 24 months follow-up. In patients with chronic total occlusion, the cumulative rates of MACEs and ST were 0.79%, 5.04%, 6.83%, 7.07% and 0%, 0.84%, 0.85%, 0.88% at 1, 9, 12, and 24 months, respectively, indicating constant rate of ST after 9 months.

Conclusions

The BioMime SES demonstrated good safety and efficacy outcomes at 24-month follow-up, with low rates of MACEs and ST in patients with CAD in the real-world setting.

Long-term outcomes following ultrathin vs thin-strut drug-eluting stents for percutaneous coronary intervention: an updated systematic review and meta-analysis of randomized control trials

OBJECTIVES

Current thin-strut 2nd generation drug eluting stents (DES) are considered as optimal standard of care for revascularization of coronary artery disease (CAD) patients undergoing percutaneous coronary intervention (PCI). Ultrathin (≤ 70 μm strut thickness) strut DES have recently been shown to reduce target lesion failure (TLF) compared to thin-strut DES. Therefore, in order to assess the validity of improved outcomes associated with ultrathin-strut DES, we conducted an updated meta-analysis that includes recently published follow-ups of previously conducted randomized controlled trials (RCTs).

METHODS

MEDLINE and Scopus were queried from their inception to May 2024 to identify studies comparing outcomes between ultrathin and current thin-strut 2nd generation DES groups. A random-effects meta-analysis was conducted to derive risk ratios (RR) from dichotomous data. The primary endpoint was long-term TLF defined as a composite of cardiac death, target vessel myocardial infarction (TV-MI) and clinically driven target lesion revascularization (CD-TLR). The secondary outcome was target-vessel failure (TVF) defined as a composite of cardiac death, TV-MI and clinically driven target-vessel revascularization (CD-TVR).

RESULTS

A total of 17 RCTs (n=22141) with a mean follow-up of 34 months were included. The risk of TLF was significantly lowered in the ultrathin DES group in comparison to thin-strut DES. A significant decrease was also noted in rates of TVF, CD-TLR and CD-TVR in the ultrathin DES vs thin-strut DES group.

CONCLUSION

The results of our analysis demonstrate a significantly reduced risk of TLF in the ultrathin DES group in comparison with thin-strut DES. Ultrathin DES was also associated with a significantly decreased risk of TVF, CD-TLR and CD-TVR.

Comparative effectiveness of ultrathin vs. standard strut drug-eluting stents: insights from a large-scale meta-analysis with extended follow-up

BACKGROUND

Newer generation ultrathin strut stents are associated with less incidence of target lesion failure (TLF) in patients undergoing percutaneous coronary intervention (PCI) in the short term. However, its long-term effect on different cardiovascular outcomes remains unknown.

OBJECTIVES

We aim to identify the effects of newer-generation ultrathin-strut stents vs. standard thickness second-generation drug-eluting stents (DES) on long-term outcomes of revascularization in coronary artery disease.

METHODS

We searched PubMed, Web of Science, Cochrane Library databases, and Scopus for randomized controlled trials (RCTs) and registries that compare newer-generation ultrathin-strut (< 70 mm) with thicker strut (> 70 mm) DES to evaluate cardioprotective effects over a period of up to 5 years. Primary outcome was TLF, a composite of cardiac death, target vessel myocardial infarction (TVMI) or target lesion revascularization (TLR). Secondary outcomes included the components of TLF, stent thrombosis (ST), and all-cause death were pooled as the standardized mean difference between the two groups from baseline to endpoint.

RESULTS

We included 19 RCTs and two prospective registries (103,101 patients) in this analysis. The overall effect on the primary outcome was in favor of second-generation ultrathin struts stents in terms of TLF at ≥ 1 year, ≥ 2 years, and ≥ 3 years (P value = 0.01, 95% CI [0.75, 0.96]), P value = 0.003, 95% CI [0.77, 0.95]), P value = 0.007, 95% CI [0.76, 0.96]), respectively. However, there was no reported benefit in terms of TLF when we compared the two groups at ≥ 5 years (P value = 0.21), 95% CI [0.85, 1.04]). Some of the reported components of the primary and secondary outcomes, such as TLR, target vessel revascularization (TVR), and TVMI, showed the same pattern as the TLF outcome.

CONCLUSION

Ultrathin-strut DES showed a beneficial effect over thicker strut stents for up to 3 years. However, at the 5-year follow-up, the ultrathin strut did not differ in terms of TLF, TLR, TVR, and TVMI compared with standard-thickness DES, with similar risks of patient-oriented composite endpoint (POCE), MI, ST, cardiac death, and all-cause mortality.

Revolutionizing Cardiovascular Frontiers: A Dive Into Cutting-Edge Innovations in Coronary Stent Technology

Plain balloon angioplasty was the initial method used to enlarge the intracoronary lumen size. However, it was linked to acute coronary closure due to early vessel recoil. This led to the invention of coronary stents, which offer mechanical support to open and maintain the vascular lumen. Nevertheless, the metallic scaffold introduced other issues, such as thrombosis and restenosis caused by neointimal proliferation. To address these concerns, polymers were employed to cover the scaffold, acting as drug reservoirs and regulators for controlled drug release. The use of polymers prevents direct contact between blood and metallic scaffolds. Drugs within the stent were incorporated to inhibit proliferation and expedite endothelialization in the healing process. Despite these advancements, adverse effects still arise due to the inflammatory reaction caused by the polymer material. Consequently, resorbable polymers and scaffolds were later discovered, but they have limitations and are not universally applicable. Various scaffold designs, thicknesses, materials, polymer components, and drugs have their own advantages and complications. Each stent generation has been designed to address the shortcomings of the preceding generation, yet new challenges continue to emerge. Conflicting data regarding the long-term safety and efficacy of coronary stents, especially in the extended follow-up, further complicates the assessment.

A Narrative Review of Ultrathin-strut Drug-eluting Stents: The Thinner the Better?

Second-generation drug-eluting stents (DES) are considered standard of care for revascularization of patients undergoing percutaneous coronary intervention. Besides the polymer and antiproliferative drug used, the metallic backbone of DES is an attractive target for further development. Ultrathin-strut DES (≤70 μm strut thickness) are more flexible, have an improved trackability and crossability compared to conventional second-generation DES. Importantly, ultrathin-strut DES reduce the risk of in-stent restenosis, thereby decreasing the risk of angiographic and clinical restenosis. In this narrative review, we will discuss the clinical outcomes of the commercially available ultrathin-strut DES.

Long-term follow-up after ultrathin vs. conventional 2nd-generation drug-eluting stents: a systematic review and meta-analysis of randomized controlled trials

AIMS

Contemporary 2nd-generation thin-strut drug-eluting stents (DES) are considered standard of care for revascularization of patients undergoing percutaneous coronary intervention. A previous meta-analysis of 10 randomized controlled trials (RCTs) with 11 658 patients demonstrated a 16% reduction in the 1-year risk of target lesion failure (TLF) with ultrathin-strut DES compared with conventional 2nd-generation thin-strut DES. Whether this benefit is sustained longer term is not known, and newer trial data may inform these relative outcomes. We therefore sought to perform an updated systematic review and meta-analysis of RCTs comparing clinical outcomes with ultrathin-strut DES (≤70 µm strut thickness) with conventional 2nd-generation thin-strut DES.

METHODS AND RESULTS

We performed a random-effects meta-analysis of all RCTs comparing ultrathin-strut DES to conventional 2nd-generation thin-strut DES. The pre-specified primary endpoint was long-term TLF, a composite of cardiac death, myocardial infarction (MI), or clinically driven target lesion revascularization (CD-TLR). Secondary endpoints included the components of TLF, stent thrombosis (ST), and all-cause death. There were 16 eligible trials in which 20 701 patients were randomized. The weighted mean follow-up duration was 2.5 years. Ultrathin-strut DES were associated with a 15% reduction in long-term TLF compared with conventional 2nd-generation thin-strut DES [relative risk (RR) 0.85, 95% confidence interval (CI) 0.76-0.96, P = 0.008] driven by a 25% reduction in CD-TLR (RR 0.75, 95% CI 0.62-0.92, P = 0.005). There were no significant differences between stent types in the risks of MI, ST, cardiac death, or all-cause mortality.

CONCLUSIONS

At a mean follow-up of 2.5 years, ultrathin-strut DES reduced the risk of TLF, driven by less CD-TLR compared with conventional 2nd-generation thin-strut DES, with similar risks of MI, ST, cardiac death, and all-cause mortality.

Long term outcomes of ultrathin versus standard thickness second-generation drug eluting stents: Meta-analysis of randomized trials

OBJECTIVE

Identify the effect of ultrathin drug eluting stents on long term outcomes in coronary artery disease.

BACKGROUND

Although second-generation drug eluting stents (DES) are superior to first-generation DES, persistence of adverse outcomes has led to continued refinement in design. Ultrathin second-generation DES have been shown to improve outcomes at 1-year follow-up. Beyond 1-year their effect remains unknown.

METHODS

PubMed, Embase and Cochrane Database were searched for randomized controlled trials that compared ultrathin (defined as <70 um) to standard thickness second-generation DES. Studies were chosen according to the PROSPERO protocol (CRD42020185374). Data from randomized controlled trials were pooled using random-effects model (Mantel-Haenszel). The primary outcome was target lesion failure (TLF) at 2 years, a composite of cardiac death, target vessel myocardial infarction, and ischemia-driven target vessel revascularization. Secondary outcomes included TLF at 3 and 5 years, the components of TLF and definite or probable stent thrombosis. Differences in outcomes between groups were presented in Forest plots as risk ratios (RR) with corresponding 95% confidence intervals (CIs) for each trial.

RESULTS

We identified 18 publications from 10 trials with14,649 patients. At 2-years there was a significant 12% reduction in TLF (RR, 0.88; 95% CI 0.78-0.99; p < 0.05) associated with the use of ultrathin DES. At 3-years, there was a significant 19% reduction in TLF with ultrathin DES (RR, 0.79; 95% CI 0.64-0.98; p < 0.05).

CONCLUSION

In patients undergoing percutaneous coronary intervention, ultrathin DES improve long term clinical outcomes.

Bioresorbable polymer and durable polymer metallic stents in coronary artery disease: a meta-analysis

BACKGROUND

Literature on bioresorbable-polymer-stents (BPS) and second-generation durable-polymer-stents (DPS) in percutaneous coronary intervention (PCI) for all comer CAD is conflicting.

METHODS

Randomized controlled studies comparing PCI among BPS and second-generation DPS were identified up until May-2020 from online databases.  Primary outcomes included are all-cause myocardial infarction (MI), cardiac-death, target-vessel-revascularization (TVR), target-vessel MI (TVMI), and stent-thrombosis (ST). Random effect method of risk ratio and confidence interval of 95% was used.

RESULTS

25 prospective randomized controlled trials with 31,822 patients (BPS n = 17,065 and DPS n = 14,757) were included in the study. Follow-up ranged between a minimum of 6 months to more than 5 years. Cardiac death (RR 1.02, 95% CI 0.89-1.45, p = 0.16) was comparable in BPS and second-generation DPS. Risk of all-cause MI was similar between BPS and DPS (RR 0.97, 95% CI 0.84-1.11, p = 0.73). TVMI (RR 0.88, 95% CI 0.69-1.11, p = 0.33) and ST rates were also comparable in BPS and DPS groups (RR 1.06, 95% CI 0.80-1.40, p = 1.00). Overall TVR had comparable outcomes between BPS and DPS (RR 0.95, 95% CI 0.79-1.14, p < 0.001); however, higher TVR was seen among BPS group at follow-up of ≥5 years (RR 1.39, 95% CI 1.12-1.14, p = 0.02). Bias was low and heterogeneity was moderate.

CONCLUSION

Patients undergoing PCI treated with BPS had comparable outcomes in terms of cardiac death, TVR, ST, TVMI, and all-cause MI to patients treated with second-generation DPS; however, BPS had higher rates of TVR for follow-up of ≥5-years.

Neointimal hyperplasia of ultra-thin stents with microcrystalline sirolimus or durable polymer everolimus-eluting stents: 6- and 24-month results of the DESSOLVE III OCT study

AIMS

The DESSOLVE III OCT substudy aimed to compare serially neointimal hyperplasia volume obstruction (%VO) between the thin-strut MiStent with early polymer elimination and nine-month sustained drug release from microcrystalline sirolimus and the durable polymer-coated everolimus-eluting XIENCE stent at six and 24 months after implantation.

METHODS AND RESULTS

The efficacy endpoint was %VO, calculated as abluminal neointimal volume/stent volume. Thirty-six patients (MiStent 16 patients, 16 lesions; XIENCE 20 patients, 22 lesions) underwent serial OCT evaluation at both six and 24 months. At six months, mean abluminal %VO was significantly lower in the MiStent group than in the XIENCE group (14.54±3.70% vs 19.11±6.70%; p=0.011), whereas the difference in %VO between the two groups decreased at 24 months (20.88±5.72% vs 23.50±7.33%; p=0.24). There was no significant difference in percentage malapposed struts and percentage uncovered struts between the two groups at both time points.

CONCLUSIONS

In the serial comparative OCT analysis of the MiStent versus the XIENCE, the MiStent showed a more favourable efficacy for preventing neointimal formation with comparable strut tissue coverage, as compared with the XIENCE at six months, but this difference in %VO decreased at 24 months so that the difference in neointima at 24 months was no longer significant.

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.

Clinical outcomes and complications of treatment with supraflex stent in patients with coronary artery disease: One-year follow-up

Cardiovascular disease is one of the most important causes of morbidity and mortality in the world. Treatment in most patients is percutanseous coronary intervention. One of new generation drug-eluting stent (DES) is Sirolimus Eluting Stent. The current study was aimed to investigate the clinical outcomes and complications of treatment with supraflex stent during one year follow up in patients with coronary artery disease. This cross-sectional study was performed on patients with myocardial ischemia who were candidate for coronary angioplasty between 2017-2018 in Imam Reza Hospital, Mashhad, Iran.. Patients were followed for four primary end points including Target lesion revascularization (TLR), stent thrombosis (ST), myocardial infarction (MI) and cardiac death (CD) for one year. Descriptive data were analyzed by Freidman at a significance level of 0.05. A total of 287 patients were enrolled in the study. There was no TLR, MI, ST and CD records in the one month follow up. Six months follow up demonstrated three TLR patients and three MI patients, but no ST and death were reported. After one year follow up, three cases of CD and four ST cases were found in patients treated with supraflex stent. Based on the Freidman test, the highest rate of TLR was revealed in a six-month follow-up when comparing with one-month and twelve-month follow-up (p = 0.05). No significant relationship was found between the other cases. The most common complications associated with supraflex stent were TLR and MI in six-month follow-up. The most likely occurrence of CD and ST were found in one year follow up.

Biodegradable polymer versus second-generation durable polymer drug-eluting stents in patients with coronary artery disease: A meta-analysis

AIMS

Biodegradable polymer drug-eluting stents (BP-DES) were developed in hopes of reducing the risk of stent thrombosis. The comparison of this new stent platform with second-generation durable polymer drug-eluting stents (DP-DES) has not been well described. We, therefore, performed a meta-analysis to evaluate the safety and efficacy profiles of BP-DES versus second-generation DP-DES in patients with coronary artery disease.

METHODS AND RESULTS

Electronic database searches were conducted, from their dates of inception to June 2018, to identify randomized controlled trials (RCTs) comparing patients with either BP-DES or second-generation DP-DES. Risk estimates were expressed as risk ratios (RRs) with 95% confidence intervals (CIs). We also performed a landmark analysis beyond 1 year and sensitivity analyses based on different variables. A total of 24,406 patients from 19 RCTs were included in the present meta-analysis. There were no significant differences between BP-DES and second-generation DP-DES for the risks of definite or probable stent thrombosis (RR 0.88; 95% CI, 0.69-1.12; P = 0.29), myocardial infarction (RR 0.97; 95% CI, 0.86-1.09; P = 0.59), cardiac death (RR 1.08; 95% CI, 0.92-1.28; P = 0.34), all-cause death (RR 1.02; 95% CI, 0.91-1.13; P = 0.77), target lesion revascularization (RR 1.05; 95% CI, 0.94-1.17; P = 0.38), and target vessel revascularization (RR 1.05; 95% CI, 0.95-1.16; P = 0.36). Similar outcomes were observed regardless of anti-proliferative drug and duration of dual antiplatelet therapy (all P > 0.05).

CONCLUSION

Our findings demonstrate similar safety and efficacy profiles between BP-DES and second-generation BP-DES, with comparable rates of stent thrombosis.

A sirolimus-eluting bioabsorbable polymer-coated stent (MiStent) versus an everolimus-eluting durable polymer stent (Xience) after percutaneous coronary intervention (DESSOLVE III): a randomised, single-blind, multicentre, non-inferiority, phase 3 trial

BACKGROUND

MiStent is a drug-eluting stent with a fully absorbable polymer coating containing and embedding a microcrystalline form of sirolimus into the vessel wall. It was developed to overcome the limitation of current durable polymer drug-eluting stents eluting amorphous sirolimus. The clinical effect of MiStent sirolimus-eluting stent compared with a durable polymer drug-eluting stents has not been investigated in a large randomised trial in an all-comer population.

METHODS

We did a randomised, single-blind, multicentre, phase 3 study (DESSOLVE III) at 20 hospitals in Germany, France, Netherlands, and Poland. Eligible participants were any patients aged at least 18 years who underwent percutaneous coronary intervention in a lesion and had a reference vessel diameter of 2·50-3·75 mm. We randomly assigned patients (1:1) to implantation of either a sirolimus-eluting bioresorbable polymer stent (MiStent) or an everolimus-eluting durable polymer stent (Xience). Randomisation was done by local investigators via web-based software with random blocks according to centre. The primary endpoint was a non-inferiority comparison of a device-oriented composite endpoint (DOCE)-cardiac death, target-vessel myocardial infarction, or clinically indicated target lesion revascularisation-between the groups at 12 months after the procedure assessed by intention-to-treat. A margin of 4·0% was defined for non-inferiority of the MiStent group compared with the Xience group. All participants were included in the safety analyses. This trial is registered with ClinicalTrials.gov, number NCT02385279.

FINDINGS

Between March 20, and Dec 3, 2015, we randomly assigned 1398 patients with 2030 lesions; 703 patients with 1037 lesions were assigned to MiStent, of whom 697 received the index procedure, and 695 patients with 993 lesions were asssigned to Xience, of whom 690 received the index procedure. At 12 months, the primary endpoint had occurred in 40 patients (5·8%) in the sirolimus-eluting stent group and in 45 patients (6·5%) in the everolimus-eluting stent group (absolute difference -0·8% [95% CI -3·3 to 1·8], p_{non-inferiority}=0·0001). Procedural complications occurred in 12 patients (1·7%) in the sirolimus-eluting stent group and ten patients (1·4%) in the everolimus-eluting stent group; no clinical adverse events could be attributed to these dislodgements through a minimum of 12 months of follow-up. The rate of stent thrombosis, a safety indicator, did not differ between groups and was low in both treatment groups.

INTERPRETATION

The sirolimus-eluting bioabsorbable polymer stent was non-inferior to the everolimus-eluting durable polymer stent for a device-oriented composite clinical endpoint at 12 months in an all-comer population. MiStent seems a reasonable alternative to other stents in clinical practice.

FUNDING

The European Cardiovascular Research Institute, Micell Technologies (Durham, NC, USA), and Stentys (Paris, France).

Stent Polymers: Do They Make a Difference?

The necessity of polymers on drug-eluting stent (DES) platforms is dictated by the need of an adequate amount and optimal release kinetic of the antiproliferative drugs for achieving ideal DES performance. However, the chronic vessel wall inflammation related to permanent polymer persistence after the drug has been eluted might trigger late restenosis and stent thrombosis. Biodegradable polymers have the potential to avoid these adverse events. A variety of biodegradable polymer DES platforms have been clinically tested, showing equal outcomes with the standard-bearer permanent polymer DES within the first year of implantation. At longer-term follow-up, promising lower rates of stent thrombosis have been observed with the early generation biodegradable polymer DES platforms compared to first-generation DES. Whether this safety benefit still persists with newer biodegradable polymer DES generations against second-generation permanent polymer DES needs to be explored.

The Effect of Fluid Shear Stress on the In Vitro Release Kinetics of Sirolimus from PLGA Films

Drug-carrying coatings of stents implanted in blood vessels are exposed to various blood flows. This study investigated the effect of fluid shear stress on the in vitro release kinetics of sirolimus from poly(lactic-co-glycolic acid) (PLGA) films. The homemade parallel plate flow chamber was used to exert quantitative shear stress on the sirolimus-carrying film. By adjusting the flow rate of the release media in the chamber, three levels of shear stress (3.6, 12.0, and 36.0 dyn/cm²) were respectively applied. For each level of shear stress employed, the release kinetics of sirolimus from the PLGA films exhibited a four-phase profile: an initial burst release phase (Phase I), a lag phase (Phase II), a second burst release phase (Phase III), and a terminal release phase (Phase IV). During Phases I and II, sirolimus was released slowly and in small amounts (<10%); however, during Phases III and IV, the drug release increased considerably. Comparisons of different shear stresses indicated that greater shear stress resulted in earlier and faster sirolimus release, with more cumulative drug release observed. PLGA film degradations (molecular weight reduction, mass loss, and surface topographical variations) were also investigated to better explain the observed drug release behavior. Consequently, fluid shear stress was found to significantly accelerate the release of sirolimus from the PLGA matrices. Therefore, this study could provide a practical method for evaluating the in vitro drug release from polymer matrices under uniform shear stress, and might help improve the design of biodegradable coatings on drug-eluting stents.

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.

Thrombotic responses to coronary stents, bioresorbable scaffolds and the Kounis hypersensitivity-associated acute thrombotic syndrome

Percutaneous transluminal coronary angioplasty with coronary stent implantation is a life-saving medical procedure that has become, nowadays, the most frequent performed therapeutic procedure in medicine. Plain balloon angioplasty, bare metal stents, first and second generation drug-eluting stents, bioresorbable and bioabsorbable scaffolds have offered diachronically a great advance against coronary artery disease and have enriched our medical armamentarium. Stented areas constitute vulnerable sites for endothelial damage, endothelial dysfunction, flow turbulence, hemorheologic changes, platelet dysfunction, coagulation changes and fibrinolytic disturbances. Implant surface attracts several proteins such as albumin, fibronectin, fibrinogen, and complement that lead to complement system activation. Macrophages recognize the implant as foreign substance due to protein adsorption and its continuous presence results in macrophage differentiation and fusion into foreign body giant cells. Polymer coating, stent metallic platforms and the released drugs can act as strong antigenic complex that apply continuous, repetitive, persistent and chronic hypersensitivity irritation to the coronary intima. The concomitant administration of oral antiplatelet drugs and environmental exposures can induce hypersensitivity inflammation. A class of platelets, activated via high-affinity and low-affinity IgE hypersensitivity receptors FCγRI, FCγRII, FCεRI and FCεRII, can induce Kounis hypersensitivity-associated thrombotic syndrome inside the stented coronaries. Type III variant of this syndrome is diagnosed when coronary artery stent thrombosis is associated with thrombus infiltrated by eosinophils or mast cells and/or when coronary intima, media and adventitia adjacent to stent, is infiltrated by eosinophils or mast cells. Careful history of hypersensitivity reactions to all implanted materials and concomitant drugs with monitoring of inflammatory mediators as well as lymphocyte transformation studies to detect hypersensitivity must be undertaken in order to avoid disastrous consequences. Food and Drug Administration recommendations for coronary stent implantation should be applied also to bioresorbable scaffolds. Further studies with inert and non-allergenic implants are necessary.

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 the Absorbable Polymer Sirolimus-Eluting Stent (MiStent) to the Durable Polymer Everolimus-Eluting Stent (Xience) (from the DESSOLVE I/II and ISAR-TEST-4 Studies)

We compared the outcomes of a novel, thin-strut, cobalt-chromium, absorbable, polymer sirolimus-eluting stent (APSES; MiStent) to the durable polymer cobalt-chromium everolimus-eluting stent (EES; Xience). A propensity-matched analysis was performed comparing data from the DES With Sirolimus and a Bioabsorbable Polymer for the Treatment of Patients With De Novo Lesions in the Native Coronary Arteries (DESSOLVE) I and II studies, evaluating the APSES to the EES arm of the Intracoronary Stenting and Angiographic Results: Test Efficacy of 3 Limus-Eluting Stents-4 study. Target lesion failure (TLF) and its components were evaluated at 12 months and annually to 3 years; 805 patients (APSES = 153; EES = 652) were included with propensity matching in 204 patients (APSES = 102; EES = 102). APSES compared with EES had lower TLF at 1 year (3.0% vs 8.0%, p = 0.12) driven by a difference in target lesion revascularization (TLR; 1% vs 6%, p = 0.05), with no difference in target vessel myocardial infarction (p = 0.56) or stent thrombosis (p = 0.31). At 3 years, TLF (5.0% vs 12.5%, p = 0.07) and TLR (2.0% vs 8.4%, p = 0.04) remained lower with APSES. By landmark analysis, there was no significant difference in TLF between 1 and 3 years (p = 0.36). In conclusion, in a propensity-matched analysis, the APSES demonstrated reduced clinically indicated TLR rates at 1 and 3 years compared with the durable polymer EES, with minimal accrual of events between 1 and 3 years.