Comparison of Vascular Responses Following New-Generation Biodegradable and Durable Polymer-Based Drug-Eluting Stent Implantation in an Atherosclerotic Rabbit Iliac Artery Model

Differences in Biologic Drug Effects and Distal Particulate Embolization in Three Paclitaxel-Coated Balloons for Femoropopliteal Lesions in a Rabbit Model

BACKGROUND

A recent meta-analysis of randomized control trials demonstrated a significantly higher risk of major amputation in patients treated with drug-coated balloons (DCBs) compared with standard treatment, especially in high-dose paclitaxel-coated DCBs. Distal particulate embolization after DCB use was considered a potential cause of the higher incidence of major amputation. The current study aimed to histologically and biologically compare biologic drug effect and distal particulate embolization in 3 DCBs (a high-dose paclitaxel-coated DCB [IN.PACT Admiral] and 2 low-dose paclitaxel-coated DCBs [Ranger and Lutonix]).

METHODS AND RESULTS

The DCBs were inflated in the healthy descending aortas of 18 rabbits, followed by euthanasia 28 days after the procedure. The treated descending aorta and distal skeletal muscles were histopathologically evaluated, and paclitaxel concentrations were measured. The paclitaxel concentration of the treated lesion was highest for Ranger, followed by IN.PACT and Lutonix (Ranger vs IN.PACT vs Lutonix: 1089 [745-2170] pmol/mg vs 638 [160-2075] pmol/mg vs 25 [10-304] pmol/mg, respectively; p<0.0001). In the histopathological evaluation, the angle of severe medial smooth muscle cell loss was largest for Ranger followed by IN.PACT and Lutonix (12.8 [8.0-20.4] degree vs 1.4 [1.2-5.2] degree vs 0.8 [0.5-2.5] degree, respectively), with significant differences for Ranger vs IN.PACT (p=0.007) and Ranger vs Lutonix (p=0.002). However, paclitaxel concentrations of distal skeletal muscles were lowest for Lutonix, followed by Ranger and IN.PACT (12 [1-58] pmol/mg vs 15 [13-21] pmol/mg vs 42 [19-108] pmol/mg, respectively, p<0.0001). The numbers of arteries with downstream DCB effects were highest for IN.PACT, followed by Ranger and Lutonix (Ranger vs IN.PACT vs Lutonix, 3 [3-4] vs 4 [3-7] vs 2 [1-2], respectively), which was consistent with the measured tissue paclitaxel concentrations.

CONCLUSION

These findings suggest that Ranger demonstrates the strongest paclitaxel effect, as well as the second-best effect regarding distal particulate embolization, making it a good treatment option for patients with peripheral artery disease among the 3 DCBs evaluated in the current study. Further clinical head-to-head comparisons with larger numbers of patients are needed to explore which DCB is the most effective and safe treatment option.Clinical Impact:The findings of the current preclinical study suggests that Ranger demonstrates the strongest paclitaxel effect, as well as the second-best effect regarding distal particulate embolization making it a good treatment for patients with intermittent claudication and chronic limb-threatening ischemia.

Lipid profile and risk factors for neoatherosclerosis after drug-eluting stent implantation in acute coronary syndrome

BACKGROUND

Predictors of neoatherosclerosis in patients who received primary percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) remain unclear.

OBJECTIVE

The aim of this study is to investigate the frequency and risk factors of neoatherosclerosis 1-year after the onset of ACS.

METHODS

This study investigated 83 patients who underwent PCI for ACS followed by 1-year follow-up optical coherence tomography. The patients were categorized into the neoatherosclerosis (n = 11) and non-neoatherosclerosis groups (n = 72). Baseline characteristics, PCI procedures, medical therapies, and blood tests at 1-year, including detailed lipid profiles, were compared between the two groups.

RESULTS

Diabetes mellitus was more prominent in the neoatherosclerosis than in the non-neoatherosclerosis group (45% vs. 17%, respectively, p = 0.03). Total cholesterol (171 ± 37 mg/dL vs. 145 ± 25 mg/dL, respectively, p < 0.01), non-high-density lipoprotein cholesterol (non-HDL-C) (124 ± 36 mg/dL vs. 94 ± 24 mg/dL, respectively, p < 0.01), low-density lipoprotein cholesterol (94 ± 36 mg/dL vs. 72 ± 19 mg/dL, respectively, p < 0.01), and lipoprotein (a) (Lp[a]) (70 [19-112] mg/dL vs. 10 [3-25] mg/dL, respectively, p = 0.03) at follow-up were significantly higher in the neoatherosclerosis group. Multivariate analysis revealed that neoatherosclerosis was associated with high serum non-HDL-C (odds ratio [OR]: 1.075; 95% confidence interval [CI]: 1.011-1.144; p < 0.01) and high serum Lp(a) levels (> 30 mg/dL) (OR: 11.0; 95% CI: 1.492-81.02; p = 0.02).

CONCLUSION

Poorly controlled non-HDL-C and Lp(a) would be risk factors of neoatherosclerosis in patients 1-year after ACS.

Serial Vascular Responses of Balloon-Expandable Stent With Biodegradable Film-Type Graft in a Rabbit Iliac Artery Dissection Model (BioGard Study)

BACKGROUND AND OBJECTIVES

Arterial dissection during endovascular therapy rarely occurs but can be lethal. A fabric-based covered graft stents yield poor clinical outcomes. A novel balloon-expandable stent with biodegradable film graft for overcoming these issues was evaluated in a rabbit iliac artery model.

METHOD

Eighteen rabbits with iliac artery dissections were induced by balloon over-inflation on angiography (Ellis type 2 or 3) and treated using the test device (3.0×24 mm). Subsequently, survived twelve animals underwent histologic examinations and micro-computed tomography (CT) at 0, 2, 4, and 8 weeks and 3, 6, 9, and 12 months and angiography at one-year.

RESULTS

There were no adverse cardiovascular events during the one-year. Early-stage histologic examination revealed complete sealing of disrupted vessels by the device, exhibiting mural hematoma, peri-stent red thrombi, and dense infiltration of inflammatory cells. Mid- and long-term histologic examination showed patent stents with neointimal hyperplasia over the stents (% area stenosis: 11.8 at 2 weeks, 26.1 at 1 month, 29.7 at 3 months, 49.2 at 9 months, and 51.0 at 1 year), along with mild peri-strut inflammatory response (Grade: 1-2 at mid-term and 0-1 at long-term). The graft film became scarcely visible after six months. Both CT and angiography revealed no instances of thrombotic occlusion or in-stent restenosis (% diameter stenosis: 5.7 at 2 weeks, 12.3 at 1 month, 14.2 at 3 months, 25.1 at 9 months, and 26.6 at 1 year).

CONCLUSIONS

The novel balloon-expandable stent with a biodegradable film graft demonstrates feasibility in managing severe artery dissection and preventing lethal vascular events in animal model.

Biological differences of three paclitaxel- and sirolimus-coated balloons on coronary lesions in a rabbit model

BACKGROUND

Drug-coated balloons (DCBs) are important treatment options for coronary artery disease; however, randomised controlled trials comparing various DCB technologies are sparse, and further investigations are needed.

AIMS

This preclinical study aimed to histologically and biologically compare the drug effects and safety of a low-dose paclitaxel-coated DCB (PCB; AGENT), a regular-dose PCB (SeQuent Please NEO) and a sirolimus-coated DCB (SCB; MagicTouch).

METHODS

The DCBs were inflated in the healthy iliac arteries of 18 rabbits, which were euthanised after 28 days. The treated iliac arteries and distal skeletal muscles were histopathologically evaluated, and drug concentrations were measured.

RESULTS

In the histopathological evaluation, the medial smooth muscle cell loss score regarding depth, an indicator of drug efficacy, was significantly higher with AGENT and SeQuent Please NEO than with MagicTouch (4.0 [3.6-4.0] vs 3.7 [3.7-4.0] vs 2.2 [2.0-2.4]), with significant differences in comparisons between AGENT and MagicTouch (p<0.01) and between SeQuent Please NEO and MagicTouch (p<0.01). AGENT and SeQuent Please NEO showed comparable drug concentrations in the treated artery (p=0.61). In contrast, the drug concentrations in distal skeletal muscles were the highest for MagicTouch, followed by SeQuent Please NEO and AGENT (28.07 [13.19-52.46] ng/mg vs 0.66 [0.22-3.76] ng/mg vs 0.25 [0.04-3.23] ng/mg, respectively).

CONCLUSIONS

This study demonstrated that PCBs might have higher efficacy and lower drug concentrations in distal skeletal muscles than the MagicTouch SCB. The efficacy of the AGENT low-dose PCB and the SeQuent Please NEO regular-dose PCB was comparable.

Tissue responses to everolimus-eluting stents implanted in severely calcified lesions following atherectomy

Histopathological examination has revealed that stents on severely calcified plaques were associated with delayed vascular healing. Although atherectomy devices can increase the number of malapposed struts, tissue responses to implanted drug eluting stents in atherectomy patients remain largely unknown. This retrospective observational study included 30 patients who underwent atherectomy and everolimus-eluting stent (EES) deployment for severely calcified coronary lesions (biodegradable polymer EES (BP-EES), n = 15; durable polymer EES (DP-EES), n  = 15). Optical coherence tomography was carried out at baseline and follow-up, and struts with acute stent malapposition (ASM) were categorized as struts on modified calcium (mod-Ca), non-modified calcium (non-mod-Ca), or non-calcium (non-Ca). Adequate vascular healing, defined as ASM resolution with neointimal coverage, was compared between the BP-EES and DP-EES groups. Multivariate linear regression analysis using a generalized estimated equation revealed that BP-EES use was associated with significantly better adequate vascular healing compared with DP-EES (odds ratio [OR]: 3.691, 95% confidence interval [CI] 1.175-11.592, P = 0.025). adequate vascular healing was associated with the underlying plaque morphology (mod-Ca vs non-mod-Ca: OR 2.833, 95% CI 1.491-5.384, P = 0.001; non-Ca vs non-mod-Ca: OR 1.248, 95% CI 0.440-3.543, P = 0.677). This study demonstrates that drug-eluting stent selection and calcium modification are possible factors affecting vascular healing of malapposed struts in severely calcified lesions.

A novel glycyrrhizin acid-coated stent reduces neointimal formation in a rabbit iliac artery model

Introduction: Most drug-eluting stents (DESs) inhibit intimal hyperplasia but impair re-endothelialization. This study aimed to evaluate in vivo strut coverage and neointimal growth in a new glycyrrhizin acid (GA)-eluting stent. Methods: New Zealand White rabbits (n = 20) with atherosclerotic plaques were randomly divided into three groups based on implanted iliac artery stents: bare-metal stents (BMSs), rapamycin-eluting stents, and GA-eluting stents. After the in vivo intravascular ultrasound (IVUS) assessment at 28 days, the vessels were harvested for scanning electron microscopy (SEM) and histology. After 4 weeks of follow-up, the stent and external elastic lamina (EEL) areas were compared among the groups. Results: The rapamycin- or GA-eluting stents significantly reduced the neointimal area compared with BMSs, though GA-eluting stents had the lowest reduction. There were more uncovered struts for rapamycin-eluting stents than those for GA-eluting stents and bare-metal stents. The endothelial nitric oxide synthase (eNOS) expression in GA-eluting stents was much higher than that in BMSs and rapamycin-eluting stents, even though the endothelial coverage between struts was equivalent between BMSs and GA-eluting stents. Moreover, GA-eluting stents markedly promoted re-endothelialization and improved arterial healing compared to rapamycin-eluting stents in a rabbit atherosclerotic model. Conclusion: In conclusion, the novel GA-coated stent used in this study inhibited intimal hyperplasia and promoted re-endothelialization.

Targeting Rho kinase to restore endothelial barrier function following vascular scaffold implantation

Vascular scaffold implantation induces injury to the intimal layer and causes discontinuity of the regenerated endothelial monolayer, compromising barrier integrity, increasing permeability, and allowing the transmigration of leukocytes and lipoproteins into the subendothelial space. Mechanical vascular wall stretching triggers Ras homolog family member A (RhoA)/Rho kinase-mediated actomyosin contractility and destabilization of adherens junctions, leading to endothelial barrier dysfunction. Assembly of intercellular adhesion and actin cytoskeletal organization of interendothelial junctions are controlled by downregulation of RhoA guanosine triphosphatase (GTPase)-mediated barrier-disruptive activity and upregulation of repressor-activator protein 1 (Rap1) and Ras-related C3 botulinum toxin substrate 1 (Rac1) GTPase-mediated cytoskeletal reorganization, leading to endothelial barrier stabilization. This review highlights the involvement of Rho GTPases in the disruption of endothelial barrier integrity following vascular scaffold implantation and the targeting of downstream Rho-associated protein kinases, which signal the network to restore endothelial barrier integrity and stability.

Histological evaluation of vascular changes after excimer laser angioplasty for neointimal formation after bare-metal stent implantation in rabbit iliac arteries

BACKGROUND

Excimer laser is used to treat coronary artery disease, especially in case of lesions with thrombus and in-stent restenosis (ISR). However, there are no in vivo preclinical studies that have evaluated the pathological reactions of the vessel wall after excimer laser ablation.

METHODS

Bare-metal stents were placed in the external iliac arteries of six healthy rabbits. Twenty-eight days later, excimer laser ablation was performed with low-power (45 (fluency)/25 (rate)) in one side, and high-power (60/40) in the opposite side, followed by optical coherence tomography (OCT) evaluation. Rabbits were sacrificed 15 min after the procedure, and histological assessment was performed.

RESULTS

Morphometry analysis of OCT showed similar stent and lumen size between low-power and high-power group. Histological evaluation suggested endothelial cell loss, fibrin deposition, and tissue loss. The low-power group showed significantly less pathological changes compared with the high-power group: angle of endothelial cell loss, 32.4° vs. 191.7° (interquartile range, 8.8°-131.7° vs. 125.7°-279.5°; p < 0.01); fibrin deposition, 1.1° vs. 59.6° (0.0°-70.4° vs. 31.4°-178.4°; p = 0.03); and tissue loss 0.0° vs. 18.2° (0.0°-8.7° vs. 0.0°-42.7°; p = 0.03).

CONCLUSIONS

The pathological changes in neointima were more prominent after high-power excimer laser ablation than after low-power excimer laser. To improve safety in clinical practice, understanding the pathological changes of tissues after excimer laser in lesions with ISR is essential.

Early vascular responses to abluminal biodegradable polymer-coated versus circumferential durable polymer-coated newer-generation drug-eluting stents in humans: a pathological study

BACKGROUND

Recent clinical studies are testing strategies for short (1-3 months) dual antiplatelet therapy following newer-generation drug-eluting stent (DES) placement. However, detailed biological responses to newer-generation DES remain unknown in humans.

AIMS

We sought to evaluate early pathologic responses to abluminal biodegradable polymer-coated (BP-) DES compared with circumferential durable polymer-coated (DP-) DES in human autopsy cases.

METHODS

The study included 38 coronary lesions with newer-generation DES implanted for <90 days (DP-DES=24, BP-DES=14) in 26 autopsy cases. The degree of strut coverage was defined as follows: grade 0 (bare), grade 1 (with fibrin or tissues/cells without endothelium), grade 2 (with single-layered endothelium), and grade 3 (with endothelium and underlying smooth muscle cell layers).

RESULTS

 The duration following implantation was similar in DP- and BP-DES (median=20 vs 17 days). A total of 2,022 struts (DP-DES=1,297, BP-DES=725) were pathologically analysed. Focal grade 2 coverage was observed as early as 5 days after the implantation in both stents. The multilevel mixed-effects ordered logistic regression model demonstrated that BP-DES exhibited greater strut coverage compared with DP-DES (odds ratio [OR]: 3.64, 95% confidence interval [CI]: 1.37-9.67; p=0.009), which remained significant after adjustment for the duration following implantation and underlying tissue characteristics (OR: 2.74, 95% CI: 1.10-6.80; p=0.030). The predictive probability of grade 2 and 3 coverage was comparably limited at 30 days (DP-DES=17.1%, BP-DES=28.7%) and increased at 90 days (DP-DES=76.5%, BP-DES=86.6%). Both stents showed low inflammation and a similar degree of fibrin deposition.

CONCLUSIONS

Single-layered endothelial coverage begins in the days after newer-generation DES placement, and BP-DES potentially exhibit faster strut coverage with smooth muscle cell infiltration than DP-DES in humans. Nevertheless, vessel healing remains suboptimal in both stents at 30 days.

Multimodal effects of asymmetric coating of coronary stents by electrospinning and electrophoretic deposition

Drug-eluting stents (DESs) are drug-coated vascular implants that inhibit smooth muscle cell proliferation and limit in-stent re-stenosis. However, traditional DESs release a single drug into the blood and cannot cope with complex mechanisms in atherosclerosis and body responses. The present study aimed to develop a novel multimodal stent by fabricating asymmetric coating with electrophoretic deposition and electrospinning. Herein, we use heparin-loaded alginate (Hep/Alg) and atorvastatin calcium-loaded polyurethane (AtvCa/PU) coatings on the stent luminal and abluminal surfaces, respectively. Scanning electron microscopy (SEM) micrographs showed that the alginate coatings had uniformity and thin thickness. Meanwhile, the PU fibers were formed without beads, with an acceptable diameter and suitable mechanical properties. PU nanofiber revealed minimal degradation in a 1-month study. The release of AtvCa and Hep continued for 8 days without a significant initial burst release. None of the stent coatings were cytotoxic or hemolytic, and PU nanofibers supported the survival of human umbilical endothelial cells (HUVEC) with high adhesion and flattened morphologies. The results indicate that electrophoretic deposition and electrospinning have significant potential for achieving asymmetric coating on stents and a promising approach for dual drug release for multimodal effects in vascular stent applications.

Coronary vasomotion after treatment with drug-coated balloons or drug-eluting stents: a prospective, open-label, single-centre randomised trial

BACKGROUND

Although recent studies have reported that drug-coated balloons (DCB) are non-inferior to drug-eluting stents (DES) for the treatment of native coronary arteries in a specific population, there is no available information concerning vasomotion after treatment with DCB.

AIMS

The aim of this study was to prospectively compare coronary vasomotion in patients with small coronary artery disease treated with DCB versus DES.

METHODS

Forty-two native lesions (2.0-3.0 mm) treated in our institution were randomly assigned to the DCB arm (n=19) or the bioabsorbable polymer everolimus-eluting stents arm (n=23) after successful predilation. At eight months after treatment, endothelium-dependent and -independent vasomotion was evaluated with intracoronary infusions in incremental doses of acetylcholine (right coronary artery: low dose 5 μg, high dose 50 μg; left coronary artery: low dose 10 μg, high dose 100 μg) and nitroglycerine (200 μg). The mean lumen diameter of the distal segment, beginning 5 mm and ending 15 mm distal to the edge of the treated segment, was quantitatively measured by angiography.

RESULTS

The luminal dimension in the treated segment did not differ between groups at the follow-up angiography. The vasoconstriction after acetylcholine infusion was less pronounced in the DCB arm than in the DES arm (low-dose: 6±13% vs -3±18%, p=0.060; high-dose: -4±17% vs -21±29%, p=0.035). The response to nitroglycerine did not differ between groups (17±13% vs 17±22%, p=0.929).

CONCLUSIONS

Vasoconstriction after acetylcholine infusion in the peri-treated region was less pronounced in the DCB arm than in the DES arm, suggesting that endothelial function in treated coronary vessels could be better preserved by DCB than by new-generation DES.

Comparison of neoatherosclerosis and a clinical outcomes between bioabsorbable versus durable polymer drug-eluting stent: Verification by optical coherence tomography analysis

BACKGROUND

Neoatherosclerosis after drug-eluting stent (DES) implantation is known to be related with increased risk of late restenosis and stent thrombosis. Neoatherosclerosis and relevant clinical outcomes between bioabsorbable polymer DES (BP-DES) and second-generation durable polymer DES (DP-DES) were evaluated by optical coherence tomography (OCT) analysis.

METHODS

A total of 311 patients (319 lesions) undergoing OCT analysis after DES implantation were enrolled and divided into two groups according to stent type (BP-DES [150 patients, 153 lesions] and DP-DES [161 patients, 166 lesions]). Follow-up OCT analysis was performed at least 9 months after index stent implantation. Neoatherosclerosis was defined as presence of thin-cap fibroatheroma, calcified plaque, and lipid plaque. Primary endpoint was the incidence of neoatherosclerosis, and the secondary endpoints were the occurrence of major adverse cardiac events (MACE), defined as a composite of death, myocardial infarction, target lesion revascularization, or stent thrombosis and to find independent predictors of neoatherosclerosis.

RESULTS

The incidence of neoatherosclerosis was lower in the BP-DES group than the DP-DES group (5.2% vs. 14.5%, p = 0.008), which was driven by lipid plaque. However, the incidence of MACE did not show statistical difference between the two groups in median 4-year follow-up (3.3% vs. 7.8%, hazard ratio 1.964, 95% confidence interval 0.688-5.611, p = 0.207). Less use of angiotensin converting enzyme inhibitors/angiotensin II receptor blockade and higher degree of neointimal hyperplasia remained independent predictors of neoatherosclerosis on Cox regression analysis.

CONCLUSIONS

Patients undergoing BP-DES implantation had lower incidence of neoatherosclerosis than DP-DES, which did not reach statistically better clinical outcomes.

In Stent Neo-Atherosclerosis: Pathophysiology, Clinical Implications, Prevention, and Therapeutic Approaches

Despite the dramatic improvements of revascularization therapies occurring in the past decades, a relevant percentage of patients treated with percutaneous coronary intervention (PCI) still develops stent failure due to neo-atherosclerosis (NA). This histopathological phenomenon following stent implantation represents the substrate for late in-stent restenosis (ISR) and late stent thrombosis (ST), with a significant impact on patient’s long-term clinical outcomes. This appears even more remarkable in the setting of drug-eluting stent implantation, where the substantial delay in vascular healing because of the released anti-proliferative agents might increase the occurrence of this complication. Since the underlying pathophysiological mechanisms of NA diverge from native atherosclerosis and early ISR, intra-coronary imaging techniques are crucial for its early detection, providing a proper in vivo assessment of both neo-intimal plaque composition and peri-strut structures. Furthermore, different strategies for NA prevention and treatment have been proposed, including tailored pharmacological therapies as well as specific invasive tools. Considering the increasing population undergoing PCI with drug-eluting stents (DES), this review aims to provide an updated overview of the most recent evidence regarding NA, discussing pathophysiology, contemporary intravascular imaging techniques, and well-established and experimental invasive and pharmacological treatment strategies.

Effects of Simulated COVID-19 Cytokine Storm on Stent Thrombogenicity

BACKGROUND

Cytokine storm-related hypercoagulation may be important in the pathogenesis of stent thrombosis in patients with SARS-CoV-2. Whether stent polymers behave differently under such conditions has never been explored.

METHODS

Fluorinated polymer-nanocoated and uncoated COBRA stents (CeloNova), BioLinx-polymer-coated Resolute Onyx stents (Medtronic), and Synergy stents (Boston Scientific), which are abluminally coated with a bioabsorbable polymer, were exposed to human blood from healthy donors which was supplemented with 400 pg/mL IL-6 and 100 pg/mL TNF-α, similar to what is seen in cytokine storm caused by SARS-CoV-2. Platelet adhesion and neutrophil activation, assessed by immunofluorescence, were compared under cytokine storm and control conditions (untreated blood) (n = 4 experimental runs).

RESULTS

Platelet adhesion values, defined as %platelet-covered area x staining intensity, were significantly lower in coated and uncoated COBRA and in Resolute Onyx than in Synergy under control conditions (1.28 × 107 ± 0.43 × 107 vs. 2.92 × 107 ± 0.49 × 107 vs. 3.57 × 107 ± 0.73 × 107 vs. 9.94 × 107 ± 0.99 × 107; p ≤0.0001). In cytokine storm, platelet adhesion values remained low in coated COBRA-PzF (1.78 × 107 ± 0.38 × 107) compared to all other devices (uncoated COBRA: 5.92 × 107 ± 0.96 × 107; Resolute Onyx: 7.27 × 107 ± 1.82 × 107; Synergy: 11.28 × 107 ± 1.08 × 107; p ≤ 0.0001). Although cytokine storm conditions significantly increased neutrophil activation in all stents, it was significantly less in coated and uncoated COBRA, and in Resolute Onyx than in Synergy.

CONCLUSIONS

Blood-biomaterials interactions may determine the thrombogenic potential of stents. Under simulated cytokine storm conditions, fluoropolymer-coated stents showed the most favorable anti-thrombogenic and anti-inflammatory properties.

Intracellular glutamine level determines vascular smooth muscle cell-derived thrombogenicity

BACKGROUND AND AIMS

The everolimus-eluting stent (EES), one of the effective stents for in-stent restenosis (ISR), has a lower incidence of stent thrombosis; however, the underlying mechanism remains unknown. This study aimed to identify the effects of everolimus on vascular metabolism and thrombogenicity and examine their mechanistic link.

METHODS

EESs and bare-metal stents were implanted in rabbit iliac arteries with smooth muscle cell (SMC)-rich neointima induced by endothelial denudation. Four weeks after stent implantation, the stented arteries were examined for histological analysis and metabolomics. Additionally, everolimus effects in coronary artery SMCs metabolism, tissue factor (TF) expression, and procoagulant activity were assessed in vitro.

RESULTS

EES-implanted arteries showed decreased neointima formation, less SMCs infiltration, and reduced TF expression. Concomitantly, they were metabolically characterized by increased levels of metabolites in amino acids, such as glutamine. Similarly, everolimus increased intracellular glutamine levels, decreased TF expression, and reduced procoagulant activity in SMCs in vitro. On the contrary, exogenous glutamine administration also increased intracellular glutamine level, decreased TF expression, and reduced procoagulant activity despite enhanced mammalian target of rapamycin (mTOR) activity.

CONCLUSIONS

Intracellular glutamine level is likely to determine vascular SMC-related thrombogenicity regardless of mTOR pathway activity. Therefore, increased intracellular glutamine level might contribute partially to the beneficial effect of EES use on stent thrombosis.

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.

Differential Vascular Responses to New-Generation Drug-Eluting Stenting According to Clinical Presentation: Three-Month Optical Coherence Tomographic Study

We evaluated early vascular responses after new-generation drug-eluting stent (DES) implantation. From 2 randomized trials, we identified 471 patients (138 patients with acute myocardial infarction [AMI] vs 333 patients with stable angina or unstable angina [SA/UA]) treated by DESs who underwent serial optical coherence tomography (OCT) from postprocedure to 3 months. At 3-month follow-up OCT, malapposed strut percentage was higher in AMI than in SA/UA (5.3% vs 0.7%, P < .001); it was markedly increased from postprocedure in AMI (2.0%-5.3%, P < .001), whereas it decreased in SA/UA (1.7%-0.7%, P < .001). Patients with AMI showed a higher risk of persistent (59% vs 37%; P < .001) or late-acquired malapposition (15% vs 8%; P = .04). Uncovered strut percentage at 3 months was also higher in AMI than in SA/UA (13.1% vs 6.7%, P < .001). The AMI presentation was the significant risk factor for both significant stent malapposition (SM, ≥200 μm; odds ratio [OR] = 3.45, CI = 1.85-7.14, P < .001) and uncovered stent (% uncovered struts >6.0%; OR = 2.44, CI = 1.35-4.76, P = .004), together with malapposed distance and postprocedural thrombi. Further, AMI presentation was the predictor for the occurrence of early period late-acquired and persistent malapposition. Serial OCT comparison analyses showed that patients with AMI compared with patients with SA/UA showed more delayed strut coverage, more severe degree SM or uncovered stents, and higher incidences of early period persistent or late-acquired SM.

Angiographic and clinical outcomes of patients implanted with ultrathin, biodegradable polymer sirolimus-eluting stents versus durable polymer drug-eluting stents for percutaneous coronary intervention: an updated meta-analysis based on randomized controlled trials

INTRODUCTION

Whether sirolimus-eluting stents constituted with ultrathin-strut and biodegradable polymers (BP-SESs) can achieve a preferable effect over current drug-eluting stents with durable polymers (DP-DESs) remains highly controversial. The aim of this analysis based on randomized controlled trials (RCTs) was to detect the clinical and angiographic differences between ultrathin (defined as a strut thickness <70 µm) BP-SESs and DP-DESs.

EVIDENCE ACQUISITION

We searched seven databases to identify eligible articles. Late lumen loss (LLL) and target lesion failure (TLF) were assessed as the primary endpoints for angiographic and clinical outcomes, respectively.

EVIDENCE SYNTHESIS

Nineteen articles containing thirteen RCTs with 14801 patients were analyzed. For the 9-month angiographic outcomes, similar results were discovered between BP-SESs and DP-DESs in terms of in-stent LLL (mean difference [MD]: -0.02 [-0.05, 0.01], P=0.23), in-segment LLL (MD: -0.01 [-0.04, 0.03], P=0.74), in-stent minimum lumen diameter (MLD) (MD: -0.01 [-0.06, 0.04], P=0.72), in-segment MLD (MD: -0.01 [-0.06, 0.05], P=0.75), in-stent diameter stenosis (DS) (MD: -1.10 [-3.36, 1.15], P=0.34), in-segment DS (MD: -0.78 [-1.97, 0.40], P=0.20), in-stent binary restenosis (BR) (risk ratio [RR]: 2.27 [0.99, 5.21], P=0.05) and in-segment BR (RR: 1.46 [0.78, 2.75], P=0.24). Regarding the 12-month clinical outcomes, there was a significant decrease in TLF and a trend of a lower incidence of target vessel failure (RR: 0.89 [0.78,1.01], P=0.08), myocardial infarction (MI) and target vessel MI.

CONCLUSIONS

With similar angiographic results, BP-SESs appeared to be superior to DP-DESs with better clinical prognoses, especially for female patients, patients with STEMI and ACS and patients without diabetes. More high-quality randomized controlled trials are needed to confirm these results.

Clinical outcomes of patients treated using very short duration dual antiplatelet therapy after implantation of biodegradable-polymer drug-eluting stents: rationale and design of a prospective multicenter REIWA registry

Several studies have demonstrated the safety and feasibility of short (3-6 months) and very short duration (< 2 months) dual antiplatelet therapy (DAPT) in patients with a durable-polymer drug-eluting stent (DP-DES). However, the clinical importance of using very short duration DAPT has yet to be established in patients with a biodegradable polymer drug-eluting stent (BP-DES). The aim of this REIWA registry (multicenter and prospective registry; investigation of clinical outcomes of patients treated with short duration dual antiplatelet therapy after implantation of biodresorbable-polymer drug-eluting stent: a multicenter, prospective registry from Iwate medical university affiliated hospitals) is to determine the safety and feasibility of using 1-month DAPT followed by P2Y12 inhibitor monotherapy in patients after BP-DES implantation. This study is an observational, prospective, multicenter registry encompassing the entire local medical region of Iwate Prefecture (northern area of mainland Japan). A total of 1200 patients who underwent successful PCI with a novel thin strut BP-DES (Synergy, Ultimaster or Orsiro) and are considered to be appropriate patients for very short DAPT, are registered and subsequently administered 1-month DAPT followed by P2Y12 inhibitor monotherapy (clopidogrel 75 mg/day or prasugrel 3.75 mg/day). The primary endpoint was a composite of cardiovascular and bleeding events, which included cardiovascular death, spontaneous myocardial infarction, definite stent thrombosis, ischemic or hemorrhagic stroke, or TIMI major or minor bleeding at 12 months. The REIWA registry (UMIN000037321) will demonstrate both the safety and feasibility of using 1-month DAPT in patients with BP-DES. Furthermore, results of this study will also be able to provide supportive evidence for P2Y12 inhibitor monotherapy after 1-month DAPT following BP-DES implantation.

Midterm Clinical Impacts of Biodegradable Polymer Everolimus-Eluting Stents Compared with Durable Polymer Everolimus-Eluting Stents: A 3-Year Propensity-Matched Study

Objectives

Our aim was to evaluate the safety and efficacy of biodegradable polymer everolimus-eluting stents (BP-EES) compared with durable polymer everolimus-eluting stents (DP-EES) in midterm.

Background

There are few data about midterm clinical outcomes of BP-EES compared with DP-EES.

Methods and Results

Between January 2016 and December 2017, 395 consecutive patients were treated with BP-EES and 391 consecutive patients were treated with DP-EES in Nagoya Heart Center. The primary endpoint was a 3-year cumulative incidence of target lesion failure (TLF) defined as cardiac death, target vessel myocardial infarction (MI), and clinical indicated target lesion revascularization (TLR). Moreover, clinical indicated target vessel revascularization (TVR) and definite stent thrombosis (ST) were also evaluated as the secondary endpoints. After propensity score matching, 327 patients were selected in each group. At 3 years, the cumulative incidence of TLF was 4.5% in the BP-EES group versus 6.5% in DP-EES (adjusted HR 0.67 (95% CI 0.33–1.30), log-rank P=0.23). Regarding the individual components of the TLF at 3 years, the cumulative incidence of target vessel MI was significantly lower in BP-EES than in DP-EES (0% versus 1.9%: adjusted HR 0.83 (95% CI 0.71–0.97), log-rank P=0.01), but there was no difference between BP-EES and DP-EES in the incidence of cardiac death and clinically indicated TLR. The cumulative 3-year incidence of definite ST was significantly lower in BP-EES than in DP-EES (0% versus 1.6%, log-rank P=0.02).

Conclusions

There were no significant differences of TLF between BP-EES and DP-EES within 3 years. In this study, BP-EES seems to prevent definite ST and be safer than DP-EES in midterm.

Cut-off value of strut-vessel distance for the resolution of acute incomplete stent apposition in the early phase using serial optical coherence tomography after cobalt-chromium everolimus-eluting stent implantation

OBJECTIVE

The purpose of this study was to identify a cut-off value to predict the resolution of incomplete-stent-apposition (ISA) after cobalt-chromium everolimus-eluting stent (CoCr-EES) implantation at early follow-up.

BACKGROUND

To date, appropriate stent apposition at the acute period using intracoronary imaging has been recommended because persistent ISA is considered to be a risk factor for stent thrombosis. We examined the indices for resolving acute ISA. In particular, we determined the cut-off value for strut vessel distance (SV-distance) as visualized by optical coherence tomography (OCT) at 8 months after CoCr-EES implantation. However, the cut-off value of SV-distance for the earlier resolution of ISA is unclear.

METHODS

A total of 95 cases and 103 stents were registered in the MECHANISM Elective substudy. The SV-distance was measured at the deepest site of the target malapposition and every 1 mm from the proximal edge to the distal edge of the mal-apposed area using OCT. Cut-off values for ISA resolution at 1 and 3 months were estimated by SV-distance using receiver operating characteristic analysis.

RESULTS

The total number of analyzed struts was 14,418 at the 1-month follow-up and 11,986 at the 3-month follow-up. The optimal SV-distance cut-off values just after stent implantation to predict ISA resolution were 185 µm at the 1-month follow-up and 195 μm at the 3-month follow-up.

CONCLUSION

For resolution of ISA, SV-distance cut-off values of 185 µm at 1 month postimplantation and 195 μm at 3 months postimplantation can be used as the index of endpoint of the percutaneous coronary intervention.

Efficacy and Safety of Ultrathin, Bioresorbable-Polymer Sirolimus-Eluting Stents Versus Thin, Durable-Polymer Everolimus-Eluting Stents for Coronary Revascularization of Patients With Diabetes Mellitus

Patients with diabetes mellitus are prone to increased adverse outcomes after percutaneous coronary intervention, even with contemporary drug-eluting stents. Randomized controlled trials have demonstrated comparable clinical outcomes between an ultrathin bioresorbable-polymer sirolimus-eluting stent (BP-SES) and a thin-strut durable-polymer everolimus-eluting stent (DP-EES) that has specific labeling for patients with diabetes. We aimed to evaluate the safety and efficacy of the BP-SES in patients with diabetes mellitus. To determine the performance of the BP-SES in diabetic patients, patient-level data from the BIOFLOW II, IV, and V randomized controlled trials were pooled. The primary end point was target lesion failure (TLF), defined as the composite of cardiovascular death, target-vessel myocardial infarction, ischemia-driven target lesion revascularization, and definite or probable stent thrombosis, at 1 year. Among 1,553 BP-SES and 791 DP-EES patients, 757 diabetic patients were identified. Of the diabetic patients included in this analysis (494 BP-SES vs 263 DP-EES), the proportion of insulin- and noninsulin-treated patients was similar between groups. The 1-year TLF rate in the diabetic population was 6.3% in the BP-SES group and 8.7% in the DP-EES group (hazard ratio 0.82, 95% confidence interval 0.047 to 1.43, p = 0.493). There were no significant differences, based on stent type or diabetes treatment regimen, in TLF hazards. In a patient-level pooled analysis of the diabetic population from randomized trials, 1-year clinical safety and efficacy outcomes were similar in patients treated with ultrathin BP-SES and thin-strut DP-EES.

Clinical Outcomes Following Implantation of Thin-Strut, Bioabsorbable Polymer-Coated, Everolimus-Eluting SYNERGY Stents

Background:

The thin-strut SYNERGY stent has an abluminal everolimus-eluting bioabsorbable polymer coating designed to facilitate vascular healing and reduce risk of stent thrombosis. In the multicenter, randomized EVOLVE II trial (The EVOLVE II Clinical Trial to Assess the SYNERGY Stent System for the Treatment of Atherosclerotic Lesion[s]), SYNERGY was noninferior to the durable polymer PROMUS Element Plus everolimus-eluting stent for the primary end point of 1-year target lesion failure. Longer-term clinical follow-up will support the relative efficacy and safety of SYNERGY.

Methods:

Patients with ≤3 native coronary lesions (reference vessel diameter ≥2.25–≤4.00 mm; length ≤34 mm) in ≤2 major epicardial vessels were randomized 1:1 to SYNERGY (N=838) or PROMUS Element Plus (N=846). EVOLVE II included a Diabetes substudy which pooled patients with diabetes mellitus from the randomized controlled trial (n=263) and from a sequential, single-arm substudy (N=203).

Results:

The 5-year target lesion failure rate was 14.3% for SYNERGY and 14.2% for PROMUS Element Plus ( P =0.91). Landmark analysis demonstrated similar rates of target lesion failure from discharge to 1-year ( P =0.90) and from 1 to 5 years ( P =0.94). Definite/probable stent thrombosis was infrequent in both arms (SYNERGY 0.7% versus PROMUS Element Plus 0.9%; P =0.75). There were no significant differences in the rates of cardiac death, myocardial infarction, or revascularization. Among patients with diabetes mellitus, the target lesion failure rate to 1-year was noninferior to a prespecified performance goal and to 5 years was 17.0%.

Conclusions:

SYNERGY demonstrated comparable outcomes to PROMUS Element Plus, with low rates of stent thrombosis and adverse events through 5 years of follow-up. Five-year clinical outcomes were favorable in patients with diabetes mellitus. These data support the long-term safety and effectiveness of SYNERGY in a broad range of patients.

Clinical Trial Registration:

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

Five-year clinical efficacy and safety of contemporary thin-strut biodegradable polymer versus durable polymer drug-eluting stents: a systematic review and meta-analysis of 9 randomized controlled trials

Very long-term data of the biodegradable polymer drug-eluting stents (BP-DES) in comparison with the contemporary durable polymer DES (DP-DES) are still to be investigated. We aimed to investigate the very long-term clinical performance of contemporary BP-DES against the DP-DES. We performed a systematic review to evaluate very long-term clinical outcomes of BP-DES versus DP-DES. Inclusion criteria were randomized design comparing BP-DES against DP-DES and follow-up duration ≥ 36 months. MEDLINE, EMBASE, and CENTRAL without restricting language or publication status were searched up to December 2018. The primary efficacy and safety endpoints were target lesion failure (TLF; a composite of cardiac death, target vessel myocardial infarction and ischemia-driven target lesion revascularization) and definite/probable stent thrombosis (ST), respectively. Primary analysis was done for the contemporary thin-strut BP- and DP-DES (strut thickness < 100 µm). A total of 9 trials comprising 10,699 patients (BP-DES, n = 6241 versus DP-DES, n = 4458) were analyzed. The mean follow-up duration was 63 months. No significant difference was found in TLF [Odds ratio (95% CI) 1.04 (0.89-1.21)] and definite/probable ST (odds ratio (95% CI) 0.78 (0.59-1.01)] between the BP- and DP-DESs. The present meta-analysis suggested that the contemporary thin-strut BP- and DP-DES have similar efficacy and safety profile at 5-year follow-up.Clinical trial registration PROSPERO; CRD42018101983 https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=101983.

Fas ligand and nitric oxide combination to control smooth muscle growth while sparing endothelium

Metallic stents cause vascular wall damage with subsequent smooth muscle cell (SMC) proliferation, neointimal hyperplasia, and treatment failure. To combat in-stent restenosis, drug-eluting stents (DES) delivering mTOR inhibitors such as sirolimus or everolimus have become standard for coronary stenting. However, the relatively non-specific action of mTOR inhibitors prevents efficient endothelium recovery and mandates dual antiplatelet therapy to prevent thrombosis. Unfortunately, long-term dual antiplatelet therapy leads to increased risk of bleeding/stroke and, paradoxically, myocardial infarction. Here, we took advantage of the fact that nitric oxide (NO) increases Fas receptors on the SMC surface. Fas forms a death-inducing complex upon binding to Fas ligand (FasL), while endothelial cells (ECs) are relatively resistant to this pathway. Selected doses of FasL and NO donor synergistically increased SMC apoptosis and inhibited SMC growth more potently than did everolimus or sirolimus, while having no significant effect on EC viability and proliferation. This differential effect was corroborated in ex vivo pig coronaries, where the neointimal formation was inhibited by the drug combination, but endothelial viability was retained. We also deployed FasL-NO donor-releasing ethylene-vinyl acetate copolymer (EVAc)-coated stents into pig coronary arteries, and cultured them in perfusion bioreactors for one week. FasL and NO donor, released from the stent coating, killed SMCs close to the stent struts, even in the presence of flow rates mimicking those of native arteries. Thus, the FasL-NO donor-combination has a potential to prevent intimal hyperplasia and in-stent restenosis, without harming endothelial restoration, and hence may be a superior drug delivery strategy for DES.

Re-endothelialisation after Synergy stent and Absorb bioresorbable vascular scaffold implantation in acute myocardial infarction: COVER-AMI study

BACKGROUND/AIMS

Drug eluting stent (DES) decrease the risk of restenosis by reducing the neointimal response. However, DES may impair strut coverage, and this has been associated with late stent/scaffold thrombosis. Bioresorbable vascular scaffold (BVS) may overcome the risk of stent/scaffold thrombosis when completely resorbed. The purpose of this randomised trial was to compare the arterial healing response in the short term, as a surrogate for safety and efficacy, between the metallic everolimus-eluting stent (Synergy; Boston Scientific, Marlborough, MA, USA) and the everolimus BVS (Absorb; Abbott Vascular, Santa Clara, CA, USA) in the particular setting of acute myocardial infarction (AMI). This pilot study sought to compare the neointimal response of metallic everolimus DES (Synergy) with polymeric everolimus BVS (Absorb) by optical coherence tomography (OCT) 3 months after an AMI.

METHODS

COVER-AMI was a single-centre, single-blind, non-inferiority, randomised controlled trial. Patients with ST segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention were randomly allocated (1:1) to treatment with the Synergy DES or Absorb BVS. The primary endpoint was the 3-month neointimal response assessed as the percentage of uncovered struts, neointimal thickness, in-stent/scaffold area obstruction, and pattern of neointima. The main secondary endpoint included the device-oriented composite endpoint according to the Academic Research Consortium definition.

RESULTS

Twenty patients without clinical and/or angiographic complications (Synergy (n = 10) or BVS (n = 10); mean age 59.0 years; 20% female) were enrolled in our centre. The stent diameter was higher in the Synergy group (3.7 ± 0.4 mm vs 3.4 ± 0.4 mm in the BVS group, p = 0.01). At 3 months, no significant differences in angiographic lumen loss were observed between the everolimus DES and everolimus BVS (0.04 mm (IQR 0.00-0.07) vs 0.11 mm (IQR 0.04-0.31), p = 0.165). OCT analysis of 420 cross-sections showed that the total neointimal area and in-stent obstruction were lower in the Synergy group, while OCT analysis at the strut level (n = 3942 struts) showed that the rate of uncovered struts was lower in the BVS group.

CONCLUSIONS

Stenting of culprit lesions in the setting of STEMI resulted in a nearly complete arterial healing for both the Synergy and the BVS devices. Lower neointimal thickness and in-stent obstruction but a higher rate of uncovered struts were observed in the Synergy group. These findings provide the basis for further exploration in clinically oriented outcome trials.

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.

Early-Phase Vascular Healing of Bioabsorbable vs. Durable Polymer-Coated Everolimus-Eluting Stents in Patients With ST-Elevation Myocardial Infarction - 2-Week and 4-Month Analyses With Optical Coherence Tomography

BACKGROUND

Despite the revolution of coronary stents, there remain concerns about the risk of stent thrombosis, especially in patients with ST-elevation myocardial infarction (STEMI). The present study compared early vascular healing as a contributing factor to reducing stent thrombosis between Xience everolimus-eluting stents (X-EES) and Synergy everolimus-eluting stents (S-EES) in patients with STEMI.

METHODS AND RESULTS

The present study included 47 patients with STEMI requiring primary percutaneous coronary intervention with X-EES (n=25) or S-EES (n=22). Optical coherence tomography (OCT) assessments of the stented lesions were performed 2 weeks and 4 months after stent implantation. Neointimal strut coverage, malapposition and the frequency of thrombus formation were evaluated. In the 2-week OCT analysis, the proportion of covered struts in S-EES (42.4±15.4%) was significantly higher than in X-EES (26.3±10.1%, P<0.001). In the 4-month OCT analysis, the proportion of covered struts in S-EES (72.2±17.9%) was still significantly higher than in X-EES (62.0±14.9%, P=0.04).

CONCLUSIONS

Compared with X-EES, S-EES showed a higher proportion of covered struts in the early phase after stent implantation for STEMI patients.

Evolution of the SYNERGY bioresorbable polymer metallic coronary stent

The SYNERGY stent is composed of thin, platinum-chromium metal alloy struts and an ultrathin, bioabsorbable poly-DL-lactide-co-glycolide polymer limited to the abluminal strut surface which elutes everolimus prior to complete resorption within 3–4 months. SYNERGY was designed to reduce inflammation and facilitate stent healing compared with permanent polymer drug eluting stents. This review summarizes the preclinical and clinical development of SYNERGY, its integration into clinical practice and future directions.

Neoatherosclerosis and Late Thrombosis After Percutaneous Coronary Intervention: Translational Cardiology and Comparative Medicine from Bench to Bedside

Neoatherosclerosis is a form of accelerated atherosclerosis that occurs within stented segments of the coronary vessel late or very late after drug-eluting stent (DES) implantation via percutaneous coronary intervention (PCI). This proliferation of neointima with a formation of new atheromatous plaque within stent struts lacking re-endothelialization can provoke thrombotic occlusion and lead to catastrophic acute coronary events. Knowing that coronary artery disease is the leading single cause of mortality worldwide and that there is a constant trend of increase in PCI procedures, it is reasonable to conclude that late thrombotic events and neoatherosclerosis post-PCI remain an important therapeutic challenge. For these reasons, early identification of patients at risk through the means of advanced imaging methods or preventive solutions available through novel technological solutions in DES design that target pro-inflammatory pathways and enable optimized arterial healing are central strategies in prevention and treatment of in-stent neoatherosclerosis and thrombosis. Due to this, pre-clinical studies performed on animal models are crucial building blocks that enable the objective and scientific assessment of innovative technological and therapeutic solutions before they are introduced to early stages of human clinical trials. A comparative medicine approach allows designing and executing experiments in animal models with a high degree of similarity with human coronary anatomy possibly promising the translation of encouraging findings to human clinical studies. The aim of this review is to provide contemporary insights on the pathophysiology of neoatherosclerosis and in-stent thrombosis and emergence of novel biomedical and technological solutions used to counter them.

In-Stent Restenosis due to Stent Recoil After Third-Generation Drug-Eluting Stent Implantation

A 72-year-old man with a heavily calcified coronary lesion underwent percutaneous coronary intervention (PCI) using a third-generation drug-eluting stent (DES) with thin stent struts. Two months after the PCI, in-stent restenosis due to stent recoil (SR) occurred. An intravascular ultrasound (IVUS) revealed deformed stent struts and heavily calcified coronary plaque. The SR probably occurred due to persistent vessel compression as a result of heavily calcified coronary plaque. We should consider using a DES with thick stent struts rather than a third-generation DES with thin stent struts in patients with a heavily calcified coronary lesion.

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.