Stent thrombosis with drug-eluting and bare-metal stents: evidence from a comprehensive network meta-analysis

Coronary stents: historical development, current status and future directions

INTRODUCTION

Coronary angioplasty with stenting has revolutionized the treatment of coronary artery disease. This article describes the history of coronary angioplasty and stenting, reviews the contemporary stents and recommendations and highlights the on-going work and potential future directions.

SOURCES OF DATA

This review examined the data on coronary stents available in PubMed.

AREAS OF AGREEMENT

Coronary artery stenting is the treatment of choice for patients requiring coronary angioplasty. Stents, and particularly drug-eluting stents, reduce the risk of restenosis, but may be associated with the hazard of late stent thrombosis. Dual anti-platelet treatment is recommended for patients receiving coronary stents.

AREAS OF CONTROVERSY

The selection of stents for various lesions and patients and the duration of anti-platelet therapy remain debated areas.

AREAS TIMELY FOR DEVELOPING RESEARCH

There are on-going preclinical and clinical studies to develop better stent platforms, more biocompatible polymers, novel anti-proliferative and anti-platelet drugs, pro-healing stents and bioresorbable scaffolds.

Safety and efficacy of second-generation everolimus-eluting Xience V stents versus zotarolimus-eluting resolute stents in real-world practice: patient-related and stent-related outcomes from the multicenter prospective EXCELLENT and RESOLUTE-Korea registries

OBJECTIVES

This study sought to compare the safety and efficacy of the Xience V/Promus everolimus-eluting stent (EES) (Abbott Vascular, Temecula, California) with the Endeavor Resolute zotarolimus-eluting stent (ZES-R) (Medtronic Cardiovascular, Santa Rosa, California) in "all-comer" cohorts.

BACKGROUND

Only 2 randomized controlled trials have compared these stents.

METHODS

The EXCELLENT (Efficacy of Xience/Promus Versus Cypher to Reduce Late Loss After Stenting) and RESOLUTE-Korea registries prospectively enrolled 3,056 patients treated with the EES and 1,998 patients treated with the ZES-R, respectively, without exclusions. Stent-related composite outcomes (target lesion failure [TLF]) and patient-related composite outcomes were compared in crude and propensity score-matched analyses.

RESULTS

Of 5,054 patients, 3,830 (75.8%) had off-label indication (2,217 treated with EES and 1,613 treated with ZES-R). The stent-related outcome (82 [2.7%] vs. 58 [2.9%], p = 0.662) and the patient-related outcome (225 [7.4%] vs. 153 [7.7%], p = 0.702) did not differ between EES and ZES-R, respectively, at 1 year, which was corroborated by similar results from the propensity score-matched cohort. The rate of definite or probable stent thrombosis (18 [0.6%] vs. 7 [0.4%], p = 0.306) also was similar. In multivariate analysis, off-label indication was the strongest predictor of TLF (adjusted hazard ratio: 2.882; 95% confidence interval: 1.226 to 6.779; p = 0.015).

CONCLUSIONS

In this robust real-world registry with unrestricted use of EES and ZES-R, both stents showed comparable safety and efficacy at 1-year follow-up. Overall incidences of TLF and definite stent thrombosis were low, even in the patients with off-label indication, suggesting excellent safety and efficacy of both types of second-generation drug-eluting stents.

Coronary stent thrombosis: current insights into new drug-eluting stent designs

The advances of interventional cardiology have been achieved by new device development, finding appropriate drug regimes, and understanding of pathomechanism. Drug-eluting stents (DES) implantation with dual anti-platelet therapy reduced revascularization without increasing mortality or myocardial infarction compared with bare-metal stenting. However, late-term stent thrombosis (ST) and restenosis limited its value and raised the safety concern. Main mechanisms of this phenomenon are impaired endothelialization and hypersensitivity reaction with polymer. The second generation DES further improved safety and/or efficacy by using thinner stent strut and biocompatible polymer. Recently, new concept DES with biodegradable polymer, polymer-free and bioabsorbable scaffold are under investigation in the quest to minimize the risk of ST.

Nickel-free stainless steel avoids neointima formation following coronary stent implantation

SUS316L stainless steel and cobalt-chromium and platinum-chromium alloys are widely used platforms for coronary stents. These alloys also contain nickel (Ni), which reportedly induces allergic reactions in some subjects and is known to have various cellular effects. The effects of Ni on neointima formation after stent implantation remain unknown, however. We developed coronary stents made of Ni-free high-nitrogen austenitic stainless steel prepared using a N2-gas pressurized electroslag remelting (P-ESR) process. Neointima formation and inflammatory responses following stent implantation in porcine coronary arteries were then compared between the Ni-free and SUS316L stainless steel stents. We found significantly less neointima formation and inflammation in arteries implanted with Ni-free stents, as compared to SUS316L stents. Notably, Ni2+ was eluted into the medium from SUS316L but not from Ni-free stainless steel. Mechanistically, Ni2+ increased levels of hypoxia inducible factor protein-1α (HIF-1α) and its target genes in cultured smooth muscle cells. HIF-1α and their target gene levels were also increased in the vascular wall at SUS316L stent sites but not at Ni-free stent sites. The Ni-free stainless steel coronary stent reduces neointima formation, in part by avoiding activation of inflammatory processes via the Ni-HIF pathway. The Ni-free-stainless steel stent is a promising new coronary stent platform.

Relation of body mass index to risk of stent thrombosis after percutaneous coronary intervention

Stent thrombosis is a devastating complication after percutaneous coronary intervention (PCI), but the influence of obesity on risk of stent thrombosis is unclear, and it is unknown if this relation is dependent on stent type. The objective of this study was to examine the relation between body mass index (BMI) and stent thrombosis after PCI with bare-metal stent (BMS) or drug-eluting stent (DES). We followed 5,515 patients who underwent PCI with implantation of ≥1 BMS or DES at a high-volume tertiary invasive cardiology center from 2000 through 2006. Only patients with a single type of stent (BMS or DES) implanted at the index PCI were included. Median follow-up period was 26 months (interquartile range 12 to 44) and definite stent thrombosis occurred in 78 patients. Hazard ratio of definite stent thrombosis adjusted for number of stents at the index PCI was 0.92 (95% confidence interval [CI] 0.86 to 0.97) for each increase in kilograms per square meter of BMI. There was no significant interaction between stent type and BMI (p = 0.48). Hazard ratios for probable stent thrombosis and possible stent thrombosis adjusted for numbers of stents at the index PCI were 1.01 (CI 0.99 to 1.03) and 0.99 (CI 0.98 to 1.01) for each increase in kilograms per square meter of BMI, respectively. In conclusion, BMI was inversely correlated with risk of definite stent thrombosis after PCI irrespective of stent type.

Comparisons of detailed arterial healing response at seven months following implantation of an everolimus- or sirolimus-eluting stent in patients with ST-segment elevation myocardial infarction

BACKGROUND

The difference of arterial healing response following everolimus-eluting stent (EES) or sirolimus-eluting stent (SES) implantation in patients with ST-segment elevated myocardial infarction (STEMI) has not been compared in detail.

METHODS

Thirty-five patients with STEMI were randomly implanted with an EES or SES (23 EES, 12 SES). At seven months, neointimal thickness (NIT) and strut malapposition were evaluated by optical coherence tomography (OCT) and the grade and heterogeneity of neointimal coverage (NIC) and development of intra-stent thrombi were evaluated by angioscopy.

RESULTS

No significant differences were noted in clinical events experienced by the two groups, although one patient with an EES died following a papillary muscle rupture and one patient with a SES experienced sub-acute stent thrombosis. On OCT, although the EES implants showed a greater NIT than the SES implants (94.8 ± 88.8 μm vs 65.6 ± 63.3 μm, P<0.0001), both the EES and SES showed an excellent suppression of neointimal proliferation in the culprit lesion of STEMI. The frequency of uncovered and malapposed struts of EES was significantly lower than that of SES (2.7% vs. 15.7%, P<0.0001, 0.7% vs. 2.3%, P<0.0001, respectively). The ratio of stents fully covered with neointima of EES group was significantly higher than that of SES group (P=0.04). Angioscopic analysis also showed greater dominant NIC grade with homogenous NIC in EES than in SES (P=0.03, P=0.0002, respectively). The incidence of massive intra-stent thrombus of EES was lower than that of SES (P=0.05).

CONCLUSION

For patients with STEMI, EES may promote better arterial healing response than SES.

Everolimus-eluting stent versus bare-metal stent in ST-segment elevation myocardial infarction (EXAMINATION): 1 year results of a randomised controlled trial

BACKGROUND

Everolimus-eluting stent (EES) reduces the risk of restenosis in elective percutaneous coronary intervention. However, the use of drug-eluting stent in patients with ST-segment elevation myocardial infarction (STEMI) is still controversial. Data regarding the performance of second-generation EES in this setting are scarce. We report the 1-year result of the EXAMINATION (clinical Evaluation of the Xience-V stent in Acute Myocardial INfArcTION) trial, comparing EES with bare-metal stents (BMS) in patients with STEMI.

METHODS

This multicentre, prospective, randomised, all-comer controlled trial was done in 12 medical centres in three countries. Between Dec 31, 2008, and May 15, 2010, we recruited patients with STEMI up to 48 h after the onset of symptoms requiring emergent percutaneous coronary intervention. Patients were randomly assigned (ratio 1:1) to receive EES or BMS. Randomisation was in blocks of four or six patients, stratified by centre and centralised by telephone. Patients were masked to treatment. The primary endpoint was the patient-oriented combined endpoint of all-cause death, any recurrent myocardial infarction, and any revascularisation at 1 year and was analysed by intention to treat. The secondary endpoints of the study included the device-oriented combined endpoint of cardiac death, target vessel myocardial infarction or target lesion revascularisation, and rates of all cause or cardiac death, recurrent myocardial infarction, target lesion or target vessel revascularisation, stent thrombosis, device and procedure success, and major and minor bleeding. This trial is registered with ClinicalTrials.gov, number NCT00828087.

FINDINGS

Of the 1504 patients randomised, 1498 patients were randomly assigned to receive EES (n=751) or BMS (n=747). The primary endpoint was similar in both groups (89 [11·9%] of 751 patients in the EES group vs 106 [14·2%] of 747 patients in the BMS group; difference -2·34 [95% CI -5·75 to 1·07]; p=0·19). Device-oriented endpoint (44 [5·9%] in the EES group vs 63 [8·4%] in the BMS group; difference -2·57 [95% CI -5·18 to 0·03]; p=0·05) did not differ between groups, although rates of target lesion and vessel revascularisation were significantly lower in the EES group (16 [2·1%] vs 37 [5·0%], p=0·003, and 28 [3·7%] vs 51 [6·8%], p=0·0077, respectively). Rates of all cause (26 [3·5%] for EES vs 26 [3·5%] for BMS, p=1·00) or cardiac death (24 [3·2%] for EES vs 21 [2·8%] for BMS, p=0·76) or myocardial infarction (10 [1·3%] vs 15 [2·0%], p=0·32) did not differ between groups. Stent thrombosis rates were significantly lower in the EES group (4 [0·5%] patients with definite stent thrombosis in the EES group vs 14 [1·9%] in the BMS group and seven [0·9%] patients with definite or probable stent thrombosis in the EES group vs 19 [2·5%] in the BMS group, both p=0·019). Although device success rate was similar between groups, procedure success rate was significantly higher in the EES group (731 [97·5%] vs 705 [94·6%]; p=0·0050). Finally, Bleeding rates at 1 year were comparable between groups (29 [3·9%] patients in the EES group vs 39 [5·2%] in the BMS group; p=0·19).

INTERPRETATION

The use of EES compared with BMS in the setting of STEMI did not lower the patient-oriented endpoint. However, at the stent level both rates of target lesion revascularisation and stent thrombosis were reduced in recipients of EES.

FUNDING

Spanish Heart Foundation.

Coronary stent choice in patients with acute myocardial infarction

A prompt reperfusion with primary percutaneous coronary intervention represents the current gold standard treatment for patients with acute myocardial infarction. In this setting, coronary stents have been shown to improve outcomes compared to plain angioplasty and are routinely used. However, the stent selection among patients with acute myocardial infarction is still a matter of some debate. An increased risk of very late (>1-year) stent thrombosis has been associated with the use of early-generation drug-eluting stents (DES), leading to concerns regarding the long-term safety of these devices. Newer-generation DES were developed with the aim of addressing this safety issue, and were recently investigated in a few randomized studies in patients with acute myocardial infarction. The objective of the present review is to summarize the accumulated evidence, to guide the stent selection in patients with acute myocardial infarction.

Zotarolimus-eluting vs. sirolimus-eluting coronary stents in patients with and without acute coronary syndromes: a SORT OUT III substudy

OBJECTIVES

To compare clinical outcomes among patients with acute coronary syndrome treated with zotarolimus-eluting and sirolimus-eluting stents in the SORT OUT III trial.

BACKGROUND

Currently, only limited data allow direct comparison of clinical outcomes among patients with acute coronary syndrome treated with a second-generation drug-eluting stent (DES) eluting zotarolimus vs. a first-generation DES eluting sirolimus.

METHODS

Patients with acute coronary syndrome (n=1052) were randomized to treatment with zotarolimus-eluting (n=506) or sirolimus-eluting (n=546) stents and followed for 18 months. The primary composite endpoint, major adverse cardiac events (MACE), was defined as a composite of cardiac death, myocardial infarction or target vessel revascularization.

RESULTS

Zotarolimus-eluting stent treatment compared to sirolimus-eluting stent treatment was associated with increased rates of MACE (8·7% vs. 5·0%; hazard ratio (HR), 1·78; 95% confidence interval (CI), 1·10-2·88; P=0·02) and TVR (6·8% vs. 3·9%; HR, 1·77; 95% CI, 1·03-3·04; P=0·04), while all-cause death, cardiac death, myocardial infarction and definite stent thrombosis did not differ significantly. In the same trial, stable angina pectoris patients (n=1206) were randomized to zotarolimus-eluting (n=614) and sirolimus-eluting (n=592) stents with similar results.

CONCLUSIONS

With and without acute coronary syndromes, patients treated with the sirolimus-eluting stent had better clinical outcomes than those treated with the zotarolimus-eluting stent.