In-stent restenosis after percutaneous coronary intervention: emerging knowledge on biological pathways

Percutaneous coronary intervention (PCI) has evolved significantly over the past four decades. Since its inception, in-stent restenosis (ISR)-the progressive reduction in vessel lumen diameter after PCI-has emerged as the main complication of the procedure. Although the incidence of ISR has reduced from 30% at 6 months with bare-metal stents to 7% at 4 years with drug-eluting stents (DESs), its occurrence is relevant in absolute terms because of the dimensions of the population treated with PCI. The aim of this review is to summarize the emerging understanding of the biological pathways that underlie ISR. In-stent restenosis is associated with several factors, including patient-related, genetic, anatomic, stent, lesion, and procedural characteristics. Regardless of associated factors, there are common pathophysiological pathways involving molecular phenomena triggered by the mechanical trauma caused by PCI. Such biological pathways are responses to the denudation of the intima during balloon angioplasty and involve inflammation, hypersensitivity reactions, and stem cell mobilization particularly of endothelial progenitor cells (EPCs). The results of these processes are either vessel wall healing or neointimal hyperplasia and/or neo-atherosclerosis. Unravelling the key molecular and signal pathways involved in ISR is crucial to identify appropriate therapeutic strategies aimed at abolishing the 'Achille's heel' of PCI. In this regard, we discuss novel approaches to prevent DES restenosis. Indeed, available evidence suggests that EPC-capturing stents promote rapid stent re-endothelization, which, in turn, has the potential to decrease the risk of stent thrombosis and allow the use of a shorter-duration dual antiplatelet therapy.

Polymer-free drug-coated vs. bare-metal coronary stents in patients undergoing non-cardiac surgery: a subgroup analysis of the LEADERS FREE trial

AIMS

To compare the outcomes of patients undergoing non-cardiac surgery (NCS) after PCI with either a drug-coated stent (DCS) or a bare-metal stent (BMS), followed by 1-month dual antiplatelet therapy and to explore the impact of the timing of NCS.

METHODS

This is a subgroup analysis of the LEADERS FREE trial. The primary safety end point was a composite of cardiac death, myocardial infarction, or stent thrombosis, and the primary efficacy end point was clinically driven target lesion revascularization (TLR).

RESULTS

Out of 2432 patients included in the LEADERS FREE trial, 278 (11.4%) underwent NCS within 1 year after PCI. Among NCS patients, the 1-year safety end point was numerically lower with DCS; however, this difference was not significant as compared to BMS (4.7% vs. 10.1%, HR: 0.459 [0.178-1.183], p = 0.099), clinically driven TLR was significantly lower after DCS (2.4% vs. 8.3%, HR: 0.281 [0.079-0.996], p = 0.036), and BARC 3-5 bleeding was similar with DCS vs. BMS (10.2% vs. 7.5%, p = 0.438). In patients treated with BMS, NCS within 3 months after PCI was associated with higher incidence of the safety end point than NCSs performed later: 14.9% vs. 4.4%, HR: 3.586 [1.012-12.709], p = 0.034. The timing of surgery had no impact on patients treated with DCS (4.7% vs. 4.7%, p = 0.947).

CONCLUSIONS

Among patients undergoing NCS after PCI, DCS-treated patients had a lower probability of clinically driven TLR compared with BMS. However, there was no significant difference in the occurrence of the primary composite safety end point or bleeding complications. Early NCS after BMS-PCI was associated with impaired safety, while the timing of NCS had no such influence after DCS implantation.

Do ultrathin strut bare-metal stents with passive coating improve efficacy in large coronary arteries? Insights from the randomized, multicenter BASKET-PROVE trials

BACKGROUND

The new generation thinner-strut silicon carbide (SiC) coated cobalt chromium (CoCr) bare-metal stents (BMS) are designed to accelerate rapid endothelialisation and reduce thrombogenicity when implanted in coronary arteries. However, smaller studies suggest higher rates of symptomatic restenosis in patients receiving the newer generation BMS. We investigated the efficacy of a newer generation ultrathin strut silicon-carbide coated cobalt-chromium (CoCr) BMS (SCC-BMS) as compared to an older thin-strut uncoated CoCr BMS (UC-BMS) in patients presenting with coronary artery disease requiring stenting of large vessels (≥3.0 mm).

METHODS

All patients randomized to SCC- (n = 761) or UC-BMS (n = 765) in the two BASKET-PROVE trials were included. Design, patients, interventions and follow-up were similar between trials except differing regimens of dual antiplatelet therapy. The primary endpoint was clinically driven target-vessel revascularization within 24 months. Safety endpoints of cardiac death, non-fatal myocardial infarction (MI), and definite/probable stent thrombosis (ST) were also assessed. We used inverse probability weighted proportional hazards Cox regressions adjusting for known confounders.

RESULTS

Demographics, clinical presentation, and risk factors were comparable between the groups, but patients receiving SCC-BMS underwent less complex procedures. The risk for clinically driven TVR was increased om the SCC-BMS group compared to the UC-BMS group (cumulative incidence, 10.6% vs. 8.4%; adjusted relative hazard [HR], 1.49 [95% CI, 1.05-2.10]). No differences in safety endpoints were detected, cardiac death (1.6% vs. 2.8%; HR, 0.62 [CI, 0.30-1.27]), non-fatal MI (3.2% vs. 2.5%; HR, 1.56 [CI, 0.83-2.91]), and definite/probable ST (0.8% vs. 1.1%; HR, 1.17 [CI, 0.39-3.50]). Differences in strut thickness between the two stents did not explain the association between stent type and clinically driven TVR.

CONCLUSIONS

In patients requiring stenting of large coronary arteries, use of the newer generation SCC-BMS was associated with a higher risk of clinically driven repeat revascularization compared to the UC-BMS with no signs of an offsetting safety benefit.

Feasibility of a Porcine Arteriovenous Shunt Model for Assessment of Acute Thrombogenicity in Bifurcation Stenting Technique By Optical Coherence Tomography

BACKGROUND

Double kissing (DK) crush stenting has been reported as a superior bifurcation stenting strategy compared to culotte stenting. However, the mechanism associated with the reduction of clinical events by DK crush stenting remains unclear. We therefore investigated the thrombogenicity of DK crush stenting and culotte stenting with both bare-metal stents (BMS) and drug-eluting stents (DES) and the feasibility of a novel porcine arteriovenous shunt model.

METHODS

High-resolution intracoronary imaging with optical coherence tomography (OCT) evaluated the bifurcation stenting models for thrombogenicity.

RESULTS

All porcine models retained continuous circulation without blood leakage. Thrombus was macroscopically demonstrated around the bifurcation in all settings. The volume of thrombus (mm³) with BMS using DK crush/culotte and DES using DK crush/culotte were 1.38/1.19 and 0.09/0.15, respectively. Culotte stenting had more thrombus in the proximal main branch, and DK crush stenting had more at the bifurcation. Unlike DK crush stenting, culotte stenting showed malapposition in the proximal main branch and bifurcation segments.

CONCLUSION

The feasibility of a porcine arteriovenous shunt model to assess thrombogenicity by OCT in bifurcation stenting technique was confirmed. OCT detected less thrombogenicity in DES when used in the bifurcation model when compared to BMS.

Drug-Eluting Stents Versus Bare-Metal Stents in Patients With End-Stage Renal Disease

BACKGROUND

The clinical outcomes of drug-eluting stents versus bare-metal stents in end-stage renal disease patients remains controversial.

METHODS

A comprehensive literature search of Pubmed, Embase and Cochrane Library from January 2000 until November 2016 was conducted to identify relevant articles. We pooled the odds ratios (OR) from individual studies and conducted heterogeneity, quality assessment and publication bias analyses.

RESULTS

A total of 18 studies with 44,194 patients were identified. Compared with bare-metal stent-treated patients, drug-eluting stent-treated patients had significantly lower short-term and long-term all-cause mortality (OR = 0.56; 95% CI: 0.48-0.65; P < 0.00001; OR = 0.78; 95% CI: 0.66-0.92; P = 0.004, respectively), myocardial infarction (OR = 0.69; 95% CI: 0.53-0.88; P = 0.003) and major adverse cardiac events (OR = 0.72; 95% CI: 0.58-0.90; P = 0.004), with no detectable difference regarding stent thrombosis (OR = 0.80; 95% CI: 0.43-1.49; P = 0.47), cardiac mortality (OR = 0.95; 95% CI: 0.89-1.02; P = 0.14) and repeat revascularization (OR = 0.81; 95% CI: 0.62-1.06; P = 0.13).

CONCLUSIONS

In patients with end-stage renal disease, the use of drug-eluting stents could significantly reduce the rates of mortality, myocardial infarction and major adverse cardiac events without increased risk of stent thrombosis. It poses imperative demands for future prospective randomized studies to define the optimal stent choice in this high-risk population.

IVUS Findings in Late and Very Late Stent Thrombosis. A Comparison Between Bare-metal and Drug-eluting Stents

INTRODUCTION AND OBJECTIVES

Stent thrombosis (ST) is a life-threatening complication after stent implantation. Intravascular ultrasound is able to discern most causes of ST. The aim of this study was to compare intravascular ultrasound findings between bare-metal stents (BMS) and drug-eluting stents (DES) in patients with late (31 days to 1 year) or very late ST (> 1 year).

METHODS

Of 250 consecutive patients with late or very late ST in 7 Spanish institutions, 114 patients (45.5% BMS and 54.5% DES) were imaged with intravascular ultrasound. Off-line intravascular ultrasound analysis was performed to assess malapposition, underexpansion, and neoatherosclerosis.

RESULTS

The median time from stent implantation to ST was 4.0 years with BMS and 3.4 years with DES (P = .04). Isolated malapposition was similarly observed in both groups (36.5% vs 46.8%; P = .18) but was numerically lower with BMS (26.6% vs 48.0%; P = .07) in patients with very late ST. Isolated underexpansion was similarly observed in both groups (13.5% vs 11.3%; P = .47). Isolated neoatherosclerosis occurred only in patients with very late ST and was more prevalent with BMS (22.9%) than with DES (6.0%); P = .02. At 2.9 years' follow-up, there were 0% and 6.9% cardiac deaths, respectively (P = .06) and recurrent ST occurred in 4.0% and 5.2% of patients, respectively (P = .60).

CONCLUSIONS

Malapposition was the most common finding in patients with late and very late ST and is more prevalent with DES in very late ST. In contrast, neoatherosclerosis was exclusively observed in patients with very late ST and mainly with BMS.

Drug-eluting balloons in patients with non-ST elevation acute coronary syndrome

BACKGROUND

We compared efficacy of bare-metal stent (BMS) and drug-eluting balloon (DEB) combination vs BMS alone, in patients with non-ST elevation acute coronary syndrome treated with percutaneous coronary intervention (PCI).

METHODS

Patients with non-ST elevation myocardial infarction (NSTEMI) or unstable angina (UA) were randomized to BMS only or BMS+DEB group. Angiographic follow-up was performed after 6 months. The primary endpoints were binary in-stent restenosis (ISR) and late lumen loss (LLL) and the secondary endpoints were target lesion revascularization (TLR), stent thrombosis (ST), and new acute coronary syndrome (ACS).

RESULTS

A total of 85 patients were enrolled, 44 (BMS) and 41 (BMS+DEB). The median age was 67 (36-84) years and 68 (80%) were male. Fifty-two patients (61.2%) had NSTEMI and 33 patients (38.8%) UA. There was no difference in patient demographics, risk factors, and clinical characteristics, except for more smokers in the BMS+DEB group 18/41 (43.9%) vs 9/44 (20.5%). At follow-up, no significant difference in binary ISR was found; p=0.593, but LLL was significantly lower in the BMS+DEB group 0.68 (0.00-2.15) mm vs 0.22 (0.00-2.35) mm; p=0.002. The difference in major adverse cardiac events (MACE) rate combining TLR, ST, and ACS, between the groups was also non-significant, 29.5% (BMS) vs 24.4% (BMS+DEB); p=0.835. One patient had a subacute ST (BMS+DEB) due to clopidogrel resistance.

CONCLUSION

Patients treated with BMS+DEB combination for non-ST elevation acute coronary syndrome had significantly less LLL in comparison to patients treated with BMS alone but without an impact on patient clinical outcomes.

Five-year outcomes for first generation drug-eluting stents versus bare-metal stents in patients with ST-segment elevation myocardial infarction: a meta-analysis of randomised controlled trials

BACKGROUND

Drug-eluting stent (DES) implantation has been proved more effective compared with bare-metal stent (BMS) implantation for ST-segment elevation myocardial infarction (STEMI) within medium follow up. However, limited information is available on the long-term safety and efficacy of DES.

METHODS

We performed a meta-analysis of randomised controlled trials (RCT) comparing DES with BMS in patients with STEMI at long-term follow up, defined as five years or more. The clinical end points were target vessel revascularisation (TVR), death, recurrent myocardial infarction (MI), stent thrombosis and very late stent thrombosis. We calculated the pooled estimate based on a fixed-effects model using odds ratio (OR) for rare events.

RESULTS

Four RCT were included, with a total of 1414 patients enrolled. Up to five years, DES showed a significant reduction in TVR (OR, 0.55; 95% confidence interval [CI], 0.55-0.77; P = 0.0005), but an increase in very late stent thrombosis (OR, 3.03; 95% CI, 1.28-7.18; P = 0.01), without increasing mortality (OR, 0.85; 95% CI, 0.59-1.20; P = 0.35), recurrent MI (OR, 1.05; 95% CI, 0.69-1.60; P = 0.80), and overall stent thrombosis (OR, 1.10; 95% CI, 0.66-1.82; P = 0.72).

CONCLUSIONS

At long-term follow-up, primary percutaneous coronary intervention with DES improved efficacy, without reducing overall safety. However, a trade-off must be made between the reduction of reintervention with DES and an increase in very late stent thrombosis.

bare-metal stents in Chinese geriatric patients

BACKGROUND & OBJECTIVE

Little is known about the relative efficacies of percutaneous coronary intervention (PCI) with drug-eluting stents (DES) and bare-metal stents (BMS) in elderly patients. The objective of this study was to evaluate the clinical outcome for geriatric patients who received either DES or BMS.

METHODS

From January 2002 to October 2005, 199 consecutive Chinese geriatric patients (≥ 75 years old) underwent PCI with coronary DES or BMS implantation at our institution. We analyzed the major clinical end points that included all-cause mortality, cardiovascular death, myocardial infarction, target lesion revascularization (TLR), stent thrombosis, and bleeding complications.

RESULTS

The three-year cumulative rates of all-cause mortality, cardiovascular death, and myocardial infarction were significantly lower in the DES group (6.3%, 3.6%, 5.4%) compared with the BMS group (16.2%, 11.5%, 14.9%; P < 0.05). No significant differences were found in the three-year cumulative rate for target lesion revascularization (6.3% vs. 4.6%, P = 0.61) or stent thrombosis (3.6% vs. 2.3%, P = 0.70). Likewise, there were no statistically significant differences in the cumulative rate for intracranial hemorrhage, or major and minor hemorrhage at three years.

CONCLUSIONS

DES-based PCI was associated with a significant reduction in the three-year cumulative rate of all-cause mortality, cardiovascular death, and myocardial infarction compared with BMS, without increased risk of TLR, stent thrombosis, or bleeding complications at three years in this group of Chinese geriatric patients.

Comparison of coronary DES and BMS in octogenarians: A systematic review and meta-analysis

Objective

Uncertainty exists regarding the relative performance of drug-eluting stents (DES) versus bare-metal stents (BMS) in octogenarians undergoing percutaneous coronary intervention (PCI). We undertook a meta-analysis to assess outcomes for DES and BMS in octogenarians undergoing PCI.

Methods

Electronic data bases of PubMed, Cochrane, and EMBASE were searched. We included randomized, controlled clinical trials (RCT) and observational studies comparing DES and BMS in octogenarians receiving PCI. The methodological qualities of eligible trials were assessed using a “risk of bias” tool. The endpoints included all-cause death, major adverse cardiac events (MACE), myocardial infarction (MI), target vessel revascularization (TVR), major bleeding, and stent thrombosis (ST). Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated for each endpoint.

Results

A total of one RCT and six observational studies were included and analyzed in this meta-analysis. All trials were of acceptable quality. At 30 days, compared with DES-treated patients, BMS-treated patients had a higher incidence of mortality (OR: 3.91, 95% CI: 1.10–13.91; P = 0.03). The OR for MACE (1.52, 95% CI: 0.56–4.17; P = 0.13), MI (0.81, 95% CI: 0.37–2.17; P = 0.23), TVR (0.75, 95% CI: 0.17–3.41; P = 0.41), major bleeding (0.77, 95% CI: 0.35–1.68; P = 0.43), and ST (1.44, 95% CI: 0.32–6.45; P = 0.33) did not reach statistical significance. At one year follow-up, the OR did not favor BMS over MACE (MACE, defined as the composite of death, myocardial infarction, and TVR) (1.87; 95% CI: 1.22–2.87; P < 0.01), MI (1.91, 95% CI: 1.22–2.99; P < 0.01), TVR (3.08, 95% CI: 1.80–5.26; P < 0.01) and ST (3.37, 95% CI: 1.12–10.13; P < 0.01). The OR for mortality (1.51; 95% CI: 0.92–2.47; P = 0.10) and major bleeding (0.85, 95% CI: 0.47–1.55; P = 0.60) did not reach statistical significance. At > 1 year follow-up, the OR for all endpoints, including mortality, MACE, MI, TVR, major bleeding, and ST, did not reach statistical significance.

Conclusions

Our meta-analysis suggests that DES is associated with favorable outcomes as compared with BMS in octogenarians receiving PCI.

Percutaneous revascularization strategies in small-vessel disease

Percutaneous coronary intervention (PCI) of small coronary vessels represents a real challenge for myocardial revascularization because of the high risk of stent-restenosis and increased risk of adverse clinical events. Moreover, small coronary arteries supply small myocardial territories therefore questioning the clinical significance of small-vessel stenoses. The definition of small-vessel disease and PCI-strategies used are very heterogeneous across studies. The present review will focus on percutaneous coronary revascularization in patients with small vessel coronary artery disease.

Ruptured plaque in a bare-metal stent 8 years after implantation-Comparison of IVUS and OCT findings

Optical coherence tomography (OCT) and intravascular ultrasound tomography (IVUS) findings in a patient with very late in-stent restenosis that was manifested as acute coronary syndrome 8 years after bare-metal stent implantation are presented. This case clearly shows the disruption of thin fibrous cap associated with a white thrombus by OCT. A superficial high signal with deep attenuation by OCT, composing more than half of the plaque, was expressed as heterogeneous tissue, mainly composed of echolucent lesion including outside the struts by IVUS. OCT was very useful, like it is for de novo vulnerable plaques, to evaluate vulnerable plaque that had formed in a previously implanted stent. On the other hand, tissue outside the stent struts could be visualized by IVUS. Combined use of OCT and IVUS was useful for understanding the plaque characteristics of ruptured vulnerable plaque that had formed in a previously implanted bare-metal stent even after stabilization of neointimal hyperplasia.