Stent thrombosis in real-world patients: a comparison of drug-eluting with bare metal stents

BackgroundAlthough the introduction of drugeluting stents (DES) has been associated with an impressive reduction in target vessel revascularisation, there has been concern about the safety profile. The aim of this study was to determine the incidence of stent thrombosis in real-world patients and evaluate the contribution of drug-eluting stents. Methods A prospective observational cohort study was conducted at a high-volume centre in Utrecht, the Netherlands. All patients who underwent a percutaneous coronary intervention (PCI) between 1 January and 31 December 2005 were evaluated. The patients were pretreated with aspirin and clopidogrel, which was continued for six months in bare metal stents (BMS) and 12 months in DES. ResultsIn 2005, 1309 patients underwent a percutaneous coronary intervention procedure with stent implantation. After a median follow-up of nine months, 1.8% (n=23) of the patients had suffered from stent thrombosis. Two cases could be attributed to incorrect use of antiplatelet agents. In 8/23 cases, a technical reason was found such as an unrecognised dissection or stent underexpansion. The timing of stent thrombosis was acute in 1/23 patients, subacute in 20/23 patients and late in 2/23 patients. In both cases of late stent thrombosis, a BMS had been used. There were no differences in stent thrombosis rates between DES and BMS (1.4 vs. 1.9%, ns.). This is remarkable since DES were used in more complex and longer lesions. ConclusionThe use of DES in routine daily practice does not appear to be associated with a higher rate of stent thrombosis than BMS. (Neth Heart J 2007;15:382-6).     

Association of Localized Hypersensitivity and In-Stent Neoatherosclerosis with the Very Late Drug-Eluting Stent Thrombosis

Background

Localized hypersensitivity reaction, delayed arterial healing, and neoatherosclerosis inside the stent have been suggested as the underlying pathologic mechanisms of very late stent thrombosis (VLST) of drug-eluting stent (DES). The present study sought to explore the prevalence of inflammatory cell infiltrates and evidence for fragments of atherosclerotic plaques in the aspirated thrombi in patients with DES VLST.

Methods and Results

From April 2004 to September 2012, 48 patients with stent thrombosis (ST) of DES underwent thrombus aspiration with retrieved material sufficient for the histopathologic analysis; early ST (EST, within 30 days): N = 17, late ST (LST, between 31 and 365 days): N = 7, and very late ST (VLST, >1 year): N = 24. Eosinophil fraction in the aspirated thrombi was significantly higher in patients with VLST (8.2±5.7%) as compared with those with EST (4.3±3.0%) and LST (5.5±3.8%) (P = 0.03). Eosinophil fraction in the aspirated thrombi was significantly higher in 12 VLST patients with angiographic peri-stent contrast staining (PSS) and/or incomplete stent apposition (ISA) by intravascular ultrasound than in 12 VLST patients without PSS or ISA (10.6±6.1% versus 5.8±4.1%, P = 0.03). Evidences for fragments of atherosclerotic plaques in the aspirated thrombi were observed only in 3 (13%) out of 24 patients with DES VLST.

Conclusions

Eosinophil fraction in the aspirated thrombi was significantly higher in patients with DES VLST as compared with those with EST and LST. Evidences for fragments of atherosclerotic plaques were relatively uncommon in patients with DES VLST.     

Modeling the transport of drugs eluted from stents: physical phenomena driving drug distribution in the arterial wall

Despite recent data that suggest that the overall performance of drug-eluting stents (DES) is superior to that of bare-metal stents, the long-term safety and efficacy of DES remain controversial. The risk of late stent thrombosis associated with the use of DES has also motivated the development of a new and promising treatment option in recent years, namely drug-coated balloons (DCB). Contrary to DES where the drug of choice is typically sirolimus and its derivatives, DCB use paclitaxel since the use of sirolimus does not appear to lead to satisfactory results. Since both sirolimus and paclitaxel are highly lipophilic drugs with similar transport properties, the reason for the success of paclitaxel but not sirolimus in DCB remains unclear. Computational models of the transport of drugs eluted from DES or DCB within the arterial wall promise to enhance our understanding of the performance of these devices. The present study develops a computational model of the transport of the two drugs paclitaxel and sirolimus eluted from DES in the arterial wall. The model takes into account the multilayered structure of the arterial wall and incorporates a reversible binding model to describe drug interactions with the constituents of the arterial wall. The present results demonstrate that the transport of paclitaxel in the arterial wall is dominated by convection while the transport of sirolimus is dominated by the binding process. These marked differences suggest that drug release kinetics of DES should be tailored to the type of drug used.     

Late stent thrombosis, endothelialisation and drug-eluting stents

Drug-eluting stents (DES) significantly reduce the risk of restenosis after percutaneous coronary revascularisation, but an increased risk of late stent thrombosis (LST) has been put forward as a major safety concern. Meta-analysis of clinical trials, however, does not support this caveat. Even so, many interventional cardiologists think that LST is associated with DES and related to delayed endothelialisation. This hypothesis is based on autopsy studies and clinical intracoronary angioscopy. In autopsy studies, differences between endothelialisation of DES and baremetal stents (BMS) have been reported. Most preclinical studies, however, have failed to show any significant differences in endothelialisation between DES and BMS. Our own studies, using the porcine coronary artery model, also suggest that DES show no differences in re-endothelialisation. However, DES do delay vascular healing and induce endothelial dysfunction. This paper will review clinical and animal studies which consider re-endothelialisation and LST. (Neth Heart J 2009;17:177–81.)     

药物涂层球囊概述及其在外周动脉疾病治疗中的应用进展

经皮经腔血管成形术(PTA)已广泛用于外周动脉疾病(PAD)的治疗。然而,该技术存在血管壁弹性回缩和内膜增生等不足。PTA术后植入金属裸支架(BMS)虽然可以减少血管壁弹性回缩,但由此引起的支架内再狭窄(ISR)又成为治疗中的一个突出问题。药物洗脱支架(DES)被用来解决狭窄问题,但晚期支架内血栓形成(LST)、内皮化延迟和必须长期抗血小板治疗等问题也随之而来。在这样的背景下,药物涂层球囊(DCB)获得了快速发展。DCB作为非支架方案,可将所携载的活性药物转移至病变段血管壁,对ISR或原发病变均有较好的治疗效果。本文简要介绍了DCB的发展历史,并通过实验室研究、动物实验和临床试验,从机制上阐述涂层技术、涂层药物、赋形剂等对DCB功效和安全性的影响以及DCB在PAD治疗中的应用进展。     

Drug-Eluting versus Bare-Metal Stent for Treatment of Saphenous Vein Grafts: A Meta-Analysis

Background

Saphenous vein grafts develop an aggressive atherosclerotic process and the efficacy of drug eluting stents (DES) in treating saphenous vein graft (SVG) lesions has not been convincingly demonstrated. The aim of this study was to review and analyze the current literature for controlled studies comparing DES versus bare metal stents (BMS) for treatment of SVG stenoses.

Methodology/Principal Findings

We searched several scientific databases and conference proceedings up to March 15, 2010 for controlled studies comparing target vessel revascularization (TVR) between DES and BMS. Summary odds ratios (OR) for the primary endpoint TVR and secondary endpoints infarction, stent thrombosis and death were calculated using random-effect models. A total of 29 studies (3 randomized controlled trials RCT) involving 7549 (202 in RCT) patients were included. The need for target vessel revascularization in the DES group tended to be lower compared to BMS for the 3 RCT (OR 0.50 [0.24–1.00]; p = 0.051) and for observational studies (0.62 [0.49–0.79]; p<0.001). There was no significant difference in the risk for myocardial infarction in the RCT (OR 1.25 [0.22–6.99]; p = 0.250) but a lower risk for DES based on the observational studies 0.68 [0.49–0.95]; p = 0.023. The risk for stent thrombosis was found to be non-different in the RCT (OR 0.78 [0.03–21.73], p = 0.885) while it was in favor of DES in the observational studies (0.58 [0.38 – 0.84]; p<0.001). The mortality was not significantly different between DES and BMS in the RCT''s (OR 2.22 [0.17 – 29.50]; p = 0.546) while the observation studies showed a decreased mortality in the DES group (0.69 [0.55–0.85]; p<0.001).

Conclusion

DES may decrease TVR rate in treatment of SVG stenoses. No differences in reinfarction rate, stent thrombosis or mortality was found between the DES and BMS groups in the RCT''s while the observational data showed lower risk for myocardial infarction, stent thrombosis and death in the DES group. This may be a result of patient selection bias in the observational studies or represent a true finding that was not the detected in the RCT analysis due to limited statistical power.     

Optimization of Drug Delivery by Drug-Eluting Stents

Drug-eluting stents (DES), which release anti-proliferative drugs into the arterial wall in a controlled manner, have drastically reduced the rate of in-stent restenosis and revolutionized the treatment of atherosclerosis. However, late stent thrombosis remains a safety concern in DES, mainly due to delayed healing of the endothelial wound inflicted during DES implantation. We present a framework to optimize DES design such that restenosis is inhibited without affecting the endothelial healing process. To this end, we have developed a computational model of fluid flow and drug transport in stented arteries and have used this model to establish a metric for quantifying DES performance. The model takes into account the multi-layered structure of the arterial wall and incorporates a reversible binding model to describe drug interaction with the cells of the arterial wall. The model is coupled to a novel optimization algorithm that allows identification of optimal DES designs. We show that optimizing the period of drug release from DES and the initial drug concentration within the coating has a drastic effect on DES performance. Paclitaxel-eluting stents perform optimally by releasing their drug either very rapidly (within a few hours) or very slowly (over periods of several months up to one year) at concentrations considerably lower than current DES. In contrast, sirolimus-eluting stents perform optimally only when drug release is slow. The results offer explanations for recent trends in the development of DES and demonstrate the potential for large improvements in DES design relative to the current state of commercial devices.     

Current status of clinically available bioresorbable scaffolds in percutaneous coronary interventions

Drug-eluting stents (DES) are widely used as first choice devices in percutaneous coronary interventions. However, certain concerns are associated with the use of DES, i.e. delayed arterial healing with a subsequent risk of neo-atherosclerosis, late stent thrombosis and hypersensitivity reactions to the DES polymer. Bioresorbable vascular scaffolds are the next step in percutaneous coronary interventions introducing the concept of supporting the natural healing process following initial intervention without leaving any foreign body materials resulting in late adverse events. The first-generation devices have shown encouraging results in multiple studies of selected patients up to the point of full bioresorption, supporting the introduction in regular patient care. During its introduction in daily clinical practice outside the previously selected patient groups, a careful approach should be followed in which outcome is continuously monitored.     

Stent Thrombosis is the Primary Cause of ST-Segment Elevation Myocardial Infarction following Coronary Stent Implantation: A Five Year Follow-Up of the SORT OUT II Study

Background

The widespread use of coronary stents has exposed a growing population to the risk of stent thrombosis, but the importance in terms of risk of ST-segment elevation myocardial infarctions (STEMIs) remains unclear.

Methods

We studied five years follow-up data for 2,098 all-comer patients treated with coronary stents in the randomized SORT OUT II trial (mean age 63.6 yrs. 74.8% men). Patients who following stent implantation were readmitted with STEMI were included and each patient was categorized ranging from definite- to ruled-out stent thrombosis according to the Academic Research Consortium definitions. Multivariate logistic regression was performed on selected covariates to assess odds ratios (ORs) for definite stent thrombosis.

Results

85 patients (4.1%), mean age 62.7 years, 77.1% men, were admitted with a total of 96 STEMIs, of whom 60 (62.5%) had definite stent thrombosis. Notably, definite stent thrombosis was more frequent in female than male STEMI patients (81.8% vs. 56.8%, p = 0.09), and in very late STEMIs (p = 0.06). Female sex (OR 3.53 [1.01–12.59]) and clopidogrel (OR 4.43 [1.03–19.01]) was associated with increased for definite stent thrombosis, whereas age, time since stent implantation, use of statins, initial PCI urgency (STEMI [primary PCI], NSTEMI/unstable angina [subacute PCI] or stable angina [elective PCI]), and glucose-lowering agents did not seem to influence risk of stent thrombosis.

Conclusion

In a contemporary cohort of coronary stented patients, stent thrombosis was evident in more than 60% of subsequent STEMIs.     

Long-term clinical efficiency of endovascular treatment using Cypher rapamycin-eluting stents in patients with coronary heart disease

The study was undertaken to analyze the long-term results in patients with coronary heart disease (CHD) one year or more after Cypher stent implantation. It covered 1221 patients. One-, two-, and three- vessel lesions were observed in 693 (56.8%), 344 (28.2%), and 184 (15%) patients, respectively. A total of 1967 Cypher stents were implanted. The results of treatment were analyzed 1 and 2 years after intervention. The efficiency of a procedure was evaluated by the following parameters: the presence or absence of anginal symptoms, the presence and absence of complications (fatal outcome, myocardial infarction). The following morphological parameters: the rate of restenosis and that of late stent thrombosis were also assessed. The results of one- and two-year follow-ups were used to make a multivariate analysis of the clinical and morphological predictors of coronary complications (fatal outcome, myocardial infarction, recurrent angina pectoris) in the late period, as well as the predictors of restenosis and late stent thrombosis. Restenosis following 1 year of Cypher stent implantation is 3.1%. The factors that significantly increase the risk of this complication within the first year are diabetes mellitus and revascularization in the patients operated on. The one-year rate of Cypher stent thromboses is 1.6%. Patients' discontinuation of antiaggregant therapy is the sole factor that significantly increases the rate of their late thromboses in this period. Within the second year of a follow-up, the rate of late Cypher stent thromboses is 1.8%. The risk of this complication is significantly increased by factors, such as a lengthy (more than 3 mm) stented portion, renal failure, and less than 40% left ventricular ejection fraction.     

药物涂层支架与金属裸支架治疗ST段抬高型心肌梗死的临床价值比较

目的：评价药物涂层支架（DES）与金属裸支架（BMS）在急性心肌梗死患者中应用的安全性和有效性。方法：选择2003年1月-2010年12月,在我院确诊的急性sT段抬高型心肌梗死（STEMI）167例患者,其中使用BMS65例,DES102例。对比分析两组患者住院期间和出院后1年内的主要心血管或脑血管事件（MAACE）的发生情况及支架内血栓形成的发生率。结果：至随访结束,BMS组有1例患者猝死,5例出现复发心绞痛。DES组有1例突发急性左心衰后死亡,1例复发心绞痛和1例发生亚急性支架内血栓。结论：DES应用于STEMI具有较好的安全性,其术后MAACE发生率较BMS低。     

The 2010s in clinical drug-eluting stent and bioresorbable scaffold research: a Dutch perspective

Dutch researchers were among the first to perform clinical studies in bare metal coronary stents, the use of which was initially limited by a high incidence of in-stent restenosis. This problem was greatly solved by the introduction of drug-eluting stents (DES). Nevertheless, enthusiasm about first-generation DES was subdued by discussions about a higher risk of very-late stent thrombosis and mortality, which stimulated the development, refinement, and rapid adoption of new DES with more biocompatible durable polymer coatings, biodegradable polymer coatings, or no coating at all. In terms of clinical DES research, the 2010s were characterised by numerous large-scale randomised trials in all-comers and patients with minimal exclusion criteria. Bioresorbable scaffolds (BRS) were developed and investigated. The Igaki-Tamai scaffold without drug elution was clinically tested in the Netherlands in 1999, followed by an everolimus-eluting BRS (Absorb) which showed favourable imaging and clinical results. Afterwards, multiple clinical trials comparing Absorb and its metallic counterpart were performed, revealing an increased rate of scaffold thrombosis during follow-up. Based on these studies, the commercialisation of the device was subsequently halted. Novel technologies are being developed to overcome shortcomings of first-generation BRS. In this narrative review, we look back on numerous devices and on the DES and BRS trials reported by Dutch researchers.

     

Luminal Flow Amplifies Stent-Based Drug Deposition in Arterial Bifurcations

Background

Treatment of arterial bifurcation lesions using drug-eluting stents (DES) is now common clinical practice and yet the mechanisms governing drug distribution in these complex morphologies are incompletely understood. It is still not evident how to efficiently determine the efficacy of local drug delivery and quantify zones of excessive drug that are harbingers of vascular toxicity and thrombosis, and areas of depletion that are associated with tissue overgrowth and luminal re-narrowing.

Methods and Results

We constructed two-phase computational models of stent-deployed arterial bifurcations simulating blood flow and drug transport to investigate the factors modulating drug distribution when the main-branch (MB) was treated using a DES. Simulations predicted extensive flow-mediated drug delivery in bifurcated vascular beds where the drug distribution patterns are heterogeneous and sensitive to relative stent position and luminal flow. A single DES in the MB coupled with large retrograde luminal flow on the lateral wall of the side-branch (SB) can provide drug deposition on the SB lumen-wall interface, except when the MB stent is downstream of the SB flow divider. In an even more dramatic fashion, the presence of the SB affects drug distribution in the stented MB. Here fluid mechanic effects play an even greater role than in the SB especially when the DES is across and downstream to the flow divider and in a manner dependent upon the Reynolds number.

Conclusions

The flow effects on drug deposition and subsequent uptake from endovascular DES are amplified in bifurcation lesions. When only one branch is stented, a complex interplay occurs – drug deposition in the stented MB is altered by the flow divider imposed by the SB and in the SB by the presence of a DES in the MB. The use of DES in arterial bifurcations requires a complex calculus that balances vascular and stent geometry as well as luminal flow.     

Comparative Efficacy and Safety of Drug-Eluting Stent and Conventional Therapies in Coronary Heart Disease Patients with In-Stent Restenosis: A Meta-Analysis

We performed a meta-analysis to compare therapeutic outcome/safety of drug-eluting stent (DES) and conventional in-stent restenosis (ISR) treatments. We browsed through large volume of clinical data by searching MEDLINE, EMBASE, Cochrane central register of controlled trials, and EBSCO databases. In this study, 11 randomized controlled trials, 17 non-randomized controlled trials, 6,330 patients, and 6,662 lesions were included. Clinical and coronary angiography follow-up for 6–16 months was included. The major outcomes were target lesion revascularization (TLR) and major adverse cardiac events (MACE). We found that DES showed advantage in TLR (OR = 0.46; 95 % CI: 0.34, 0.62; P < 0.00001), MACE (OR = 0.51; 95 % CI: 0.34, 0.77; P = 0.001), Late Lumen Loss (IV = ?0.30; 95 % CI: ?0.44, ?0.15; P < 0.0001), stenosis of lumen diameter (OR = ?17.45; 95 % CI: ?23.69, ?11.21; P < 0.00001), and restenosis (OR = 0.26; 95 % CI: 0.17, 0.40; P < 0.00001) over conventional ISR treatment. Regarding cardiac death (OR = 0.80; 95 % CI: 0.55, 1.17; P = 0.25), myocardial infarction (OR = 1.00;95 %CI: 0.66, 1.51; P = 1.00) and late thrombosis (OR = 0.70; 95 % CI: 0.42, 1.17; P = 0.18), there was no significant difference between different treatments. We, therefore, concluded that in treating percutaneous coronary intervention–ISR, DES was more effective in reducing incidence of TLR, MACE, and restenosis, and decreasing severity of late lumen loss/stenosis of lumen diameter compared with bare metal stent, percutaneous transluminal coronary angioplasty, intracoronary brachytherapy, and cutting balloon treatments. There was no significant difference between DES and conventional therapy for ISR. As suggested by current statistical analysis, DES after ISR did not involve a higher incidence of cardiac death, myocardial infarction, and thrombosis.     

Improving smooth muscle cell exposure to drugs from drug-eluting stents at early time points: a variable compression approach

The emergence of drug-eluting stents (DES) as a viable replacement for bare metal stenting has led to a significant decrease in the incidence of clinical restenosis. This is due to the transport of anti-restenotic drugs from within the polymer coating of a DES into the artery wall which arrests the cell cycle before restenosis can occur. The efficacy of DES is still under close scrutiny in the medical field as many issues regarding the effectiveness of DES drug transport in vivo still exist. One such issue, that has received less attention, is the limiting effect that stent strut compression has on the transport of drug species in the artery wall. Once the artery wall is compressed, the stents ability to transfer drug species into the arterial wall can be reduced. This leads to a reduction in the spatial therapeutic transfer of drug species to binding sites within the arterial wall. This paper investigates the concept of idealised variable compression as a means of demonstrating how such a stent design approach could improve the spatial delivery of drug species in the arterial wall. The study focused on assessing how the trends in concentration levels changed as a result of artery wall compression. Five idealised stent designs were created with a combination of thick struts that provide the necessary compression to restore luminal patency and thin uncompressive struts that improve the transport of drugs therein. By conducting numerical simulations of diffusive mass transport, this study found that the use of uncompressive struts results in a more uniform spatial distribution of drug species in the arterial wall.     

Stents Eluting 6-Mercaptopurine Reduce Neointima Formation and Inflammation while Enhancing Strut Coverage in Rabbits

Background

The introduction of drug-eluting stents (DES) has dramatically reduced restenosis rates compared with bare metal stents, but in-stent thrombosis remains a safety concern, necessitating prolonged dual anti-platelet therapy. The drug 6-Mercaptopurine (6-MP) has been shown to have beneficial effects in a cell-specific fashion on smooth muscle cells (SMC), endothelial cells and macrophages. We generated and analyzed a novel bioresorbable polymer coated DES, releasing 6-MP into the vessel wall, to reduce restenosis by inhibiting SMC proliferation and decreasing inflammation, without negatively affecting endothelialization of the stent surface.

Methods

Stents spray-coated with a bioresorbable polymer containing 0, 30 or 300 μg 6-MP were implanted in the iliac arteries of 17 male New Zealand White rabbits. Animals were euthanized for stent harvest 1 week after implantation for evaluation of cellular stent coverage and after 4 weeks for morphometric analyses of the lesions.

Results

Four weeks after implantation, the high dose of 6-MP attenuated restenosis with 16% compared to controls. Reduced neointima formation could at least partly be explained by an almost 2-fold induction of the cell cycle inhibiting kinase p27^Kip1. Additionally, inflammation score, the quantification of RAM11-positive cells in the vessel wall, was significantly reduced in the high dose group with 23% compared to the control group. Evaluation with scanning electron microscopy showed 6-MP did not inhibit strut coverage 1 week after implantation.

Conclusion

We demonstrate that novel stents coated with a bioresorbable polymer coating eluting 6-MP inhibit restenosis and attenuate inflammation, while stimulating endothelial coverage. The 6-MP-eluting stents demonstrate that inhibition of restenosis without leaving uncovered metal is feasible, bringing stents without risk of late thrombosis one step closer to the patient.     

Five-year clinical follow-up of the STENTYS self-apposing stent in complex coronary anatomy: a single-centre experience with report of specific angiographic indications

Objectives

We sought to investigate angiographic indications for the use of the STENTYS technique and evaluated the long-term safety and clinical efficacy of the stent.

Background

Coronary lesions involving complex anatomy, including aneurysmatic, ectatic, or tapered vessel segments often carry a substantial risk of stent malapposition. The self-apposing stent technique may reduce the risk of stent malapposition and therefore improve clinical outcomes.

Methods

A total of 120 consecutive patients treated with the STENTYS stent were included (drug-eluting stent (DES) n?=?101, bare-metal stent (BMS) n?=?19). All lesions were scored for angiographic indications for the STENTYS stent, including aneurysms, ectasias, tapering, absolute diameters, bifurcation lesions, and saphenous vein grafts. Off-line quantitative coronary angiography analyses were performed pre-procedure and post-procedure. Five years follow-up was obtained including cardiac death, target vessel myocardial infarction (TV-MI), target vessel revascularisation, stent thrombosis, and the composite endpoint target vessel failure (cardiac death, TV-MI and target vessel revascularisation).

Results

Angiographic indications for STENTYS use were aneurysm (30%), ectasia (19%), tapering (27%), bifurcation lesions (8%), and saphenous vein graft lesions (16%) and absolute diameters (22%). Mean maximal diameter was 4.51?±?0.99?mm. At 5?year follow-up target vessel failure rates were 24.1% in the total cohort (DES 22.8% vs. BMS 33%, p?=?0.26). Definite stent thrombosis rate was 3.8% at 5?year follow-up in this cohort with complex and high-risk lesions (DES 4.5% vs. BMS 0%, p?=?0.39).

Conclusions

Angiographic indications for the use of the self-apposing stent were complex lesions with atypical coronary anatomy. Our data showed reasonable stent thrombosis rates at 5?year follow-up, considering the high-risk lesion characteristics.

     

Bridging therapy for early surgery in patients on dual antiplatelet therapy after drug-eluting stent implantation

Objectives

To evaluate stent-related adverse cardiac events and bleeding complications within 30 days after surgical procedures in patients with recent drug-eluting stent (DES) implantation, in whom a bridging protocol was used.

Methods

In our centre a bridging protocol is used in patients scheduled for cardiac or non-cardiac surgery within 6 months after PCI with DES implantation. Clopidogrel and in some cases also acetylsalicylic acid is discontinued 5 days prior to the planned intervention and patients are admitted 2 to 3 days before the intervention for tirofiban infusion. This is discontinued 4 h before intervention. Close postoperative monitoring is performed and double antiplatelet therapy is restarted as soon as possible. Thirty-six consecutive patients were included in the protocol, 15 receiving coronary artery bypass graft and 21 non-cardiac interventions. Thrombotic and bleeding complications were studied for up to 30 days after the bridged procedure.

Results

No incidences of stent thrombosis or other adverse cardiac events (mortality, myocardial infarction) were seen in up to 30 days of follow-up. However, 6 bleeding events were reported of which 5 required a blood transfusion.

Conclusion

Our bridging protocol in patients requiring surgery after recent PCI with DES seems adequate to prevent stent thrombosis in this high-risk group. The bleeding risk is not insignificant but in our patient group controllable without major late sequelae. Larger studies should be performed to establish safety and efficacy in order to develop guidelines for these patients.     

Results of coronary stenting in relation to the length of an implanted stent

The paper considers the impact of the length of an implanted stent on the early and late outcomes of intracoronary stenting. The study included 177 patients on a retrospective basis. They all underwent intracoronary stenting of 215 stenoses. All the patients were divided into three groups in relation to the length of an implanted segment (under 20 mm, 20-30 mm, and under 30 mm). In 16 (9.04%) of the 177 patients, for complete stenosis correction, several, but not one, stents were inserted, i.e. multiple stenting of a coronary stenting was performed. The stents were implanted by the conventional procedure. There was no significant difference in clinical and angiographic success rates between the patients of all three groups. There were no complications, such as transmural myocardial infarction and deaths in any groups. Acute stent thrombosis was noted only in 1 (1.8%). There was no significant difference in the incidence of subacute stent thrombosis between Groups 2 and 3 patients. No case of subacute thrombosis of implanted stents was noted in Group 1 patients. Thus, acute and subacute stent thromboses were observed in 4 (2.3%) patients, they being all from Groups 2 and 3. There was no significant difference in the development of restenosis between Groups 1 and 2 and Groups 2 and 3. At the same time, restenosis significantly more frequently developed in patients from Group 3 than in those from Group 1. Thus, the findings indicate that the length of a stented segment is an important factor that influence both early and late outcomes of intracoronary stenting.     

Assessment of mechanical integrity for drug-eluting renal stent with micro-sized drug reservoirs

The drug-eluting stent (DES) has become the gold standard worldwide for the treatment of cardiovascular diseases. In recent years, an innovative variation of the DES with micro-sized drug reservoirs has been introduced. It allows programmable drug delivery with both spatial and temporal control and has several potential advantages over traditional DESs. However, creating such reservoirs on the stent struts may weaken the structure of the stent scaffolding and compromise its mechanical integrity. In this study, we propose to use this innovative stent concept in the renal indication for potential treatment of both renal artery stenosis (upstream) and its associated kidney diseases (downstream) at the same time. The effects of these micro-sized drug reservoirs on several key clinically relevant functional attributes of the drug-eluting renal stent were systematically and quantitatively investigated. Finite element models were developed to predict the mechanical integrity of a balloon-expandable stent at various stages. Results show that (1) creating drug reservoirs on a stent could impact the stent fatigue resistance to certain degrees; (2) drug reservoirs on the stent crowns lead to greater loss in all key stent attributes than reservoirs on either bar arms or connectors and (3) the proposed optimised depot stent was proven to be feasible and could triple drug capacity than the current DESs, with marginal trade-off in its key clinical attributes. These results can serve as the guidelines to help future stent designs to achieve the best combination of stent structural integrity and smart drug delivery in the future.