Late and Very Late Stent Thrombosis in Patients With Second-Generation Drug-Eluting Stents

Long-term cardiovascular outcomes of biodegradable polymer drug eluting stents in patients with diabetes versus non-diabetes mellitus: a meta-analysis

BACKGROUND

Today, diabetes mellitus (DM) has become a worldwide concern. DM is a major risk factor for the development of cardiovascular diseases (CVD). Eligible patients with CVD are treated invasively by percutaneous coronary intervention (PCI) whereby a stent is implanted inside the coronary vessel with the particular lesion to allow sufficient blood flow. Newer scientific research have shown that even though associated with a lower rate of re-stenosis, first-generation drug eluting stents (DES) were associated with a higher rate of late stent thrombosis. Recently, newer stents, namely biodegradable polymer DES (BP-DES) have been developed to overcome the safety issues of earlier generation DES. In this analysis we aimed to systematically compare the long term (≥ 12 months) adverse cardiovascular outcomes observed in DM versus non-DM patients who were implanted with BP-DES.

METHODS

Cochrane central, MEDLINE (Subset PubMed), EMBASE, Web of Science, http://www.

CLINICALTRIALS

gov and Google scholar were searched for relevant publications involving BP-DES in patients with DM versus non-DM and their associated adverse cardiovascular outcomes. The mean follow-up time period ranged from 12 to 120 months. Data analysis was carried out with the latest version of the RevMan software (version 5.4). Based on the Mantel-Haenszel test, risk ratios (RR) with 95% confidence intervals (CI) were calculated and used to represent the results following analysis.

RESULTS

Seven (7) studies with a total number of 10,246 participants were included in this analysis. Stents which were implanted during PCI were BP-DES. Participants were enrolled from the year 2006 to 2013. Our current results showed that in patients who were implanted with BP-DES, the risks of major adverse cardiac events (RR: 1.30, 95% CI: 1.18-1.43; P = 0.00001), myocardial infarction (RR: 1.48, 95% CI: 1.14-1.93; P = 0.003), all-cause mortality (RR: 1.70, 95% CI: 1.29-2.23; P = 0.0002), cardiac death (RR: 1.93, 95% CI: 1.28-2.93; P = 0.002), target vessel revascularization (RR: 1.35, 95% CI: 1.03-1.77; P = 0.03), target lesion revascularization (RR: 1.28, 95% CI: 1.07-1.54; P = 0.007) and target lesion failure (RR: 1.79, 95% CI: 1.52-2.12; P = 0.00001) were significantly higher in the DM group. Definite and probable stent thrombosis (RR: 1.80, 95% CI: 1.28-2.55; P = 0.0009) were also significantly higher in the DM group.

CONCLUSIONS

Diabetes mellitus was an independent risk factor associated with long term adverse cardiovascular outcomes following PCI with BP-DES.

Ultra-thin everolimus-eluting stents in atherosclerotic lesions: Three years follow-up with subgroup analysis of ultra-long stents

OBJECTIVES

To assess the long-term (3 years) safety and efficacy of Tetrilimus everolimus-eluting stent (EES) and subgroup analysis of outcomes of ultra-long (44/48 mm) Tetrilimus EES implantation in patients with long coronary lesions.

MATERIAL AND METHODS

In this observational, single-centre, single-arm, investigator-initiated registry, 558 patients who underwent implantation of Tetrilimus EES for the treatment of coronary artery disease were retrospectively included. The primary endpoint was occurrence of any major adverse cardiac event (MACE) at 12 months follow-up (composite of cardiac death, myocardial infarction [MI], and target lesion revascularization [TLR]) and we hereby report 3 years follow-up data. Stent thrombosis was assessed as a safety endpoint. A subgroup analysis of patients with long coronary lesions is also reported.

RESULTS

A total of 558 patients (57.0 ± 10.2 years) received 766 Tetrilimus EES (1.3 ± 0.5 stents/patient) to treat 695 coronary lesions. In subgroup analysis of 143 patients implanted with ultra-long EES, 155 lesions were intervened successfully with only one Tetrilimus EES (44/48 mm) implanted per lesion. At 3 years, event rates of 9.1% MACE with predominance of MI (4.4%), followed by 2.9% TLR and 1.7% cardiac death, and only 1.0% stent thrombosis were reported in overall population, while in a subgroup of patients implanted with ultra-long EES, 10.4% MACE and 1.5% stent thrombosis were reported.

CONCLUSIONS

Three years clinical outcomes showed favourable long-term safety and excellent performance of Tetrilimus EES in high-risk patients and complex coronary lesions in routine clinical practice, including a subgroup of patients with long coronary lesions, with acceptable primary and safety endpoints.

Simultaneous Multi-Vessel Very Late Stent Thrombosis in Acute ST-Segment Elevation Myocardial Infarction

Simultaneous multi-vessel very later stent thrombosis (VLST) is a very rare complication of percutaneous coronary intervention (PCI). We present a case of simultaneous multi-vessel VLST as the cause of acute ST-segment elevation myocardial infarction (STEMI). PCI of the culprit vessel was performed at acute presentation. Resolution of in-stent thrombosis in non-culprit vessels was noted on coronary angiography 2 days later. Our case suggests that PCI for culprit lesion in acute setting may be a reasonable option for simultaneous multi-vessel VLST.

Drug-coated balloons in the treatment of acute myocardial infarction (Review)

Drug-eluting stents are the standard revascularization strategy for the treatment of symptomatic coronary artery disease. However, in-stent restenosis (ISR), stent thrombosis and reinfarction of target lesions following stent implantation present challenges. Drug-coated balloons (DCBs), which deliver antiproliferative drugs into the vessel wall without stent implantation, are a novel treatment option for percutaneous coronary intervention and have been proven to act as a promising strategy in the treatment of ISR and coronary small vessel disease. However, their role in acute myocardial infarction (AMI) remains unclear. The present review discusses current evidence for the treatment of AMI with DCBs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A scoring system to predict the occurrence of very late stent thrombosis following percutaneous coronary intervention for acute coronary syndrome

We aimed to derive and validate an effective risk score to identify high-risk patients of very late stent thrombosis (VLST), following percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS). Stepwise multivariable Cox regression was used to build the risk model using data from 5,185 consecutive ACS patients treated with PCI (derivation cohort) and 2,058 patients from the external validation cohort. Eight variables were independently associated with the development of VLST: history of diabetes mellitus, previous PCI, acute myocardial infarction as admitting diagnosis, estimated glomerular filtration rate <90 ml/min/1.73 m², three-vessel disease, number of stents per lesion, sirolimus-eluting stent, and no post-dilation. Based on the derived score, patients were classified into low- (≤7), intermediate- (8-9), and high- (≥10) risk categories. Observed VLST rates were 0.5%, 2.2%, and 8.7% and 0.45%, 2.3%, and 9.3% across the 3 risk categories in the derivation and validation cohorts, respectively. High discrimination (c-statistic = 0.80 and 0.82 in the derivation and validation cohorts, respectively) and excellent calibration were observed in both cohorts. VLST risk score, a readily useable and efficient tool to identify high-risk patients of VLST after PCI for ACS, may aid in risk-stratification and pre-emptive decision-making.

Micropatterning of a 2-methacryloyloxyethyl phosphorylcholine polymer surface by hydrogenated amorphous carbon thin films for endothelialization and antithrombogenicity

The existing first-generation drug-eluting stent (DES) has caused late and very late stent thrombosis related to incomplete stent endothelialization. Hence, biomaterials that possess sufficient anti-thrombogenicity and endothelialization with the controlled drug release system have been highly required. In this work, we have developed a newly designed drug-release platform composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, a non-thrombogenic polymer, and micropatterned hydrogenated amorphous carbon (a-C:H), a cell-compatible thin film. The platelet adhesion and the endothelial cell adhesion behavior on the micropatterned substrates were investigated in vitro. The results indicated that the micropatterned a-C:H/MPC polymer substrates effectively supported the human umbilical vein endothelial cell (HUVEC) proliferation, while suppressing the platelet adhesion. Interestingly, the HUVEC exhibited different shape and behavior by changing the island size of the micropatterned a-C:H. By introducing both a non-thrombogenic polymer and cell-compatible thin films through a simple patterning method, we demonstrated that the platform had the potential to be utilized as a base material for DES with cell controllability. STATEMENT OF SIGNIFICANCE: The current first-generation drug-eluting stents (DES) would cause late and very late stent thrombosis due to the incomplete endothelialization of the metal stent material. In this work, we have developed a new DES platform composed of a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer micropatterned by hydrogenated amorphous carbon (a-C:H). Two types of differently micropatterned a-C:H stent surface were made. Our studies revealed that the micropatterned a-C:H/MPC polymer substrates could effectively enhance the endothelial cell (EC) proliferation, simultaneously suppressing the platelet adhesion, becoming a highly biocompatible material especially for indwelling devices including a drug-release device. The new drug-release platform could be utilized as a base material for cell-controllable coating on DES.

Long-term Outcomes of Primary Percutaneous Coronary Intervention with Second-generation Drug-eluting Stents in ST-elevation Myocardial Infarction Patients Caused by Very Late Stent Thrombosis

Background:

The ST-segment elevation myocardial infarction (STEMI) patients due to stent thrombosis (ST) remain a therapeutic challenge for a clinician. Till date, very few researches have been conducted regarding the safety and effectiveness of primary percutaneous coronary intervention (PCI) with second-generation drug-eluting stents (DES) for STEMI caused by very late ST (VLST). This retrospective study evaluated the safety, efficacy, and outcomes of primary PCI with second-generation DES for STEMI due to VLST compared with primary PCI for STEMI due to de novo lesion.

Methods:

Between January 2007 and December 2013, STEMI patients with primary PCI in Fuwai Hospital had only second-generation DES implanted for de novo lesion (558 patients) and VLST (50 patients) were included in this retrospective study. The primary end points included cardiac death and reinfarction. The secondary end points included cardiac death, reinfarction, and target lesion revascularization. Continuous variables were expressed as mean (standard deviation) or median (interquartile range) and compared by Student's t-test or Mann-Whitney U-test as appropriate. Categorical variables were expressed as counts and percentages, and comparison of these variables was performed with Chi-square or Fisher's exact test. A two-tailed value of P < 0.05 was considered statistically significant for all comparisons. Statistical analyses were performed by SAS software (version 9.4, SAS Institute Inc., Cary, USA) for Windows.

Results:

In-hospital primary end point and the secondary end point were no significant differences between two groups (P = 1.000 and P = 1.000, respectively). No significant differences between two groups were observed according to the long-term primary end point and the secondary end point. Kaplan-Meier survival curves showed no significant difference between the two groups in the primary end point and the secondary end point at 2 years (P = 0.340 and P = 0.243, respectively). According to Cox analysis, female, intra-aortic balloon pump support, and postprocedural thrombolysis in myocardial infarction flow 3 were found to be independent predictors for long-term follow-up.

Conclusion:

Primary PCI with second-generation DES is a reasonable choice for STEMI patients caused by VLST.

Meta-analysis of randomized controlled trials on efficacy and safety of extended thienopyridine therapy after drug-eluting stent implantation

BACKGROUND

The potential benefits and risks of extended thienopyridine therapy beyond 12 months after drug-eluting stent (DES) implantation remain unclear.

METHODS

Randomized controlled trials (RCTs) were searched in PubMed, EMBASE, the Cochrane Library and China National Knowledge Infrastructure databases. The adverse clinical endpoints were compared between 12 months group (aspirin alone) and >12 months group (additional thienopyridine plus aspirin after 12-month dual antiplatelet therapy). Odds ratios (ORs) with 95% confidence intervals (95% CIs) were used as summary statistics. A random-effect model was used in the meta-analysis process.

RESULTS

Finally, three RCTs incorporating 16,265 participants were included in this meta-analysis. The results indicated that the incidences of myocardial infarction (1.55% vs. 2.90%; OR =0.58; 95% CI, 0.40-0.84; P=0.004) and stent thrombosis (0.32% vs. 0.98%; OR =0.35; 95% CI, 0.20-0.62; P<0.001) in the >12 months group were significantly lower than the 12 months group. However, compared to the 12 months group, the extended thienopyridine therapy markedly increased the risk of bleeding events (2.09% vs. 1.28%; OR =1.64; 95% CI, 1.23-2.17; P<0.001). The risks of stroke (0.78% vs. 0.84%; P=0.67) and cardiac death (0.94% vs. 0.89%; P=0.61) were similar between the two groups.

CONCLUSIONS

The synthesis of available evidence indicates that a regimen of extended thienopyridine therapy beyond 12 months may significantly reduce the risks of myocardial infarction and stent thrombosis but increase the risk of bleeding events in the patients who have received DESs implantation.

Secreted Matrix Metalloproteinase-9 of Proliferating Smooth Muscle Cells as a Trigger for Drug Release from Stent Surface Polymers in Coronary Arteries

Cardiovascular diseases are the leading causes of death in industrialized countries. Atherosclerotic coronary arteries are commonly treated with percutaneous transluminal coronary intervention followed by stent deployment. This treatment has significantly improved the clinical outcome. However, triggered vascular smooth muscle cell (SMC) proliferation leads to in-stent restenosis in bare metal stents. In addition, stent thrombosis is a severe side effect of drug eluting stents due to inhibition of endothelialization. The aim of this study was to develop and test a stent surface polymer, where cytotoxic drugs are covalently conjugated to the surface and released by proteases selectively secreted by proliferating smooth muscle cells. Resting and proliferating human coronary artery smooth muscle cells (HCASMC) and endothelial cells (HCAEC) were screened to identify an enzyme exclusively released by proliferating HCASMC. Expression analyses and enzyme activity assays verified selective and exclusive activity of the matrix metalloproteinase-9 (MMP-9) in proliferating HCASMC. The principle of drug release exclusively triggered by proliferating HCASMC was tested using the biodegradable stent surface polymer poly-l-lactic acid (PLLA) and the MMP-9 cleavable peptide linkers named SRL and AVR. The specific peptide cleavage by MMP-9 was verified by attachment of the model compound fluorescein. Fluorescein release was observed in the presence of MMP-9 secreting HCASMC but not of proliferating HCAEC. Our findings suggest that cytotoxic drug conjugated polymers can be designed to selectively release the attached compound triggered by MMP-9 secreting smooth muscle cells. This novel concept may be beneficial for stent endothelialization thereby reducing the risk of restenosis and thrombosis.

Successful treatment of very late drug-eluting stent thrombosis using bare-metal stent evaluated using intravascular ultrasound and optical frequency domain imaging

A 65-year-old man who underwent percutaneous coronary intervention with sirolimus-eluting stents (SESs) 2 years ago was admitted with recurrent acute chest pain. Coronary angiography showed thrombotic occlusion within the SESs. After aspiration thrombectomy, multi-focal peri-stent contrast staining (PSS) was observed. Optical frequency domain imaging (OFDI) showed intracoronary thrombus, incomplete stent apposition (ISA), and multiple inter-strut hollows. Intravascular ultrasound (IVUS) images showed positive vessel remodeling. We deployed bare-metal stents in the SESs. Follow-up angiography showed no in-stent restenosis or PSS. OFDI showed well-covered stent surface with homogeneous neointima, without ISA. Additionally, IVUS images showed that the vessel remodeling had not worsened.

Expression of OATP2B1 as determinant of drug effects in the microcompartment of the coronary artery

Clinical success of coronary drug-eluting stents (DES) is hampered by simultaneous reduction of smooth muscle cell (HCASMC) and endothelial cell proliferation due to unspecific cytotoxicity of currently used compounds. Previous in vitro data showing SMC-specific inhibition of proliferation suggested that statins may be suitable candidates for DES. It was aim of this study to further investigate statins as DES drug candidates to identify mechanisms contributing to their cell-selectivity. In vitro proliferation assays comparing the influence of various statins on HCASMC and endothelial cells confirmed that atorvastatin exhibits HCASMC-specificity. Due to similar expression levels of the drug target HMG-CoA reductase in both cell types, cellular accumulation of atorvastatin was assessed, revealing enhanced uptake in HCASMC most likely driven by significant expression of OATP2B1, a known uptake transporter for atorvastatin. In accordance with the finding that endogenous OATP2B1 influenced cellular accumulation in HCASMC we used this transporter as a tool to identify teniposide as new DES candidate drug with HCASMC-specific effects. We describe OATP2B1 as a determinant of pharmacokinetics in the coronary artery. Indeed, endogenously expressed OATP2B1 significantly influences the uptake of substrate drugs, thereby governing cell specificity. Screening of candidate drugs for interaction with OATP2B1 may be used to promote SMC-specificity.

microRNAs Distinctively Regulate Vascular Smooth Muscle and Endothelial Cells: Functional Implications in Angiogenesis, Atherosclerosis, and In-Stent Restenosis

Endothelial cells (EC) and vascular smooth muscle cells (VSMC) are the main cell types within the vasculature. We describe here how microRNAs (miRs)--noncoding RNAs that can regulate gene expression via translational repression and/or post-transcriptional degradation--distinctively modulate EC and VSMC function in physiology and disease. In particular, the specific roles of miR-126 and miR-143/145, master regulators of EC and VSMC function, respectively, are deeply explored. We also describe the mechanistic role of miRs in the regulation of the pathophysiology of key cardiovascular processes including angiogenesis, atherosclerosis, and in-stent restenosis post-angioplasty. Drawbacks of currently available therapeutic options are discussed, pointing at the challenges and potential clinical opportunities provided by miR-based treatments.

New stent surface materials: the impact of polymer-dependent interactions of human endothelial cells, smooth muscle cells, and platelets

Despite the development of new coronary stent technologies, in-stent restenosis and stent thrombosis are still clinically relevant. Interactions of blood and tissue cells with the implanted material may represent an important cause of these side effects. We hypothesize material-dependent interaction of blood and tissue cells. The aim of this study is accordingly to investigate the impact of vascular endothelial cells, smooth muscle cells and platelets with various biodegradable polymers to identify a stent coating or platform material that demonstrates excellent endothelial-cell-supportive and non-thrombogenic properties. Human umbilical venous endothelial cells, human coronary arterial endothelial cells and human coronary arterial smooth muscle cells were cultivated on the surfaces of two established biostable polymers used for drug-eluting stents, namely poly(ethylene-co-vinylacetate) (PEVA) and poly(butyl methacrylate) (PBMA). We compared these polymers to new biodegradable polyesters poly(l-lactide) (PLLA), poly(3-hydroxybutyrate) (P(3HB)), poly(4-hydroxybutyrate) (P(4HB)) and a polymeric blend of PLLA/P(4HB) in a ratio of 78/22% (w/w). Biocompatibility tests were performed under static and dynamic conditions. Measurement of cell proliferation, viability, glycocalix width, eNOS and PECAM-1 mRNA expression revealed strong material dependency among the six polymer samples investigated. Only the polymeric blend of PLLA/P(4HB) achieved excellent endothelial markers of biocompatibility. Data show that PLLA and P(4HB) tend to a more thrombotic response, whereas the polymer blend is characterized by a lower thrombotic potential. These data demonstrate material-dependent endothelialization, smooth muscle cell growth and thrombogenicity. Although polymers such as PEVA and PBMA are already commonly used for vascular implants, they did not sufficiently meet the criteria for biocompatibility. The investigated biodegradable polymeric blend PLLA/P(4HB) evidently represents a promising material for vascular stents and stent coatings.

The evolution of coronary stents: a brief review

Percutaneous coronary intervention is the most prevalent method for coronary artery revascularization. Initial interventions using balloon angioplasty had limited efficacy because coronary dissections, arterial recoil, and neointimal formation led to high rates of abrupt vessel closure and clinical restenosis. With the introduction of coronary stents, vascular dissections were stabilized and arterial recoil was eliminated, but neointimal accumulation remained problematic, resulting in the development of in-stent restenosis (ISR) in 20%-30% of cases. Drug-eluting stents (DESs) were developed to release antiproliferative agents at the site of arterial injury to attenuate neointimal formation. Although DESs have incrementally improved outcomes after percutaneous coronary intervention, delayed re-endothelialization and stent thrombosis remain important challenges. Herein we review the pathophysiology of ISR, stent thrombosis, and briefly summarize the clinical evidence behind first- and second-generation DESs. Moreover, we discuss advancements in our understanding of the pathogenesis of ISR and potential novel therapeutic strategies to improve clinical outcomes.