A narrative review of progress in airway stents

Background and ObjectiveAirway stents, used to restore airway patency, are mostly utilized by patients with malignant airway strictures, and are occasionally used in a range of other airway related diseases, including conditions which result in benign stenosis, malacia, and fistula. There has been an increasing number of airway stents that are being developed thanks to improvements in interventional therapy. However, the method of promoting airway stents for clinical application remains undetermined. Herein, we describe the recent advances in airway stents by reviewing the published studies, providing the reference for clinical decision-making and further research on airway stents.MethodsRelevant articles between January 1964 and November 2021 were obtained from PubMed, Web of Science, and EMBASE databases. The terms “metallic”, “silicone”, “drug-eluting", “biodegradable”, “radioactive”, “three-dimensional (3D)”, and “stents” were searched in different combinations.Key Content and FindingsIn this review, we focus on the latest evidence in terms of the application of various stents with novel materials and designs including novel metallic, novel silicone, drug-eluting, biodegradable, radioactive, and 3D stents for airway stenosis. Despite reducing the well-known complications of all current commercially available stents, novel stents are still in their infancy without a long track record of utility and safety, and remain some limitations. There are more steps to be taken before such stents enter routine clinical practice.ConclusionsA combination of 3D-printing method and biodegradable material may present a promising avenue of solving the existing problems pertaining to “classic” stents and has potential to become the main trend in the future.     

Outcomes of stenting with overlapping drug-eluting stents versus overlapping drug-eluting and bare-metal stents for the treatment of diffuse coronary lesions

Introduction

We investigated the outcomes of stenting with overlapping drug-eluting stents (DES) versus overlapping stenting with a combination of drug-eluting and bare metal stents (BMS) in very long ≥(≥ 25 mm).

Methods and Results

Fifty-two patients treated with either overlapping DES-DES (n = 22) or DES-BMS (n = 30) were selected from a registry of 588 patients with very long coronary lesions. Patients with acute myocardial infarction (MI) within the preceding 48 hours were excluded. The DES-DES combination was more frequently used for longer lesions compared with the DES-BMS group (47.95 ± 9.25 vs 39.98 ± 9.15 mm, p = 0.003). Left anterior descending artery lesions were also more frequently treated with the DES-DES combination (95.5 vs 66.7%, p = 0.02). In four patients in the DES-BMS group, overlapping stents were used for the coverage of dissections. Peri-procedural non-Q-wave MI occurred in one patient in the DES-BMS group. On follow up, only one case of non-fatal MI occurred in a patient with overlapping DES-DES.

Conclusion

Overlapping a BMS in the proximal part of a long DES instead of exclusive deployment of two or more overlapped DES seems to be a safe and feasible therapeutic strategy in our practice.     

Long-term clinical outcomes of drug-eluting stents vs. 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.     

Safety and efficacy of drug-eluting stents and bare metal stents in acute coronary syndrome

Compared with medical therapy, percutaneous coronary intervention has been shown to reduce the rates of death and recurrent ischemia in patients presenting with acute coronary syndromes (ACS). In the current interventional era, both drug-eluting stents (DES) and bare-metal stents (BMS) have been widely used, despite the fact that the use of DES in the context of ACS was initially an “off-label” indication and that ACS has been associated with stent thrombosis (ST). In contrast to the wealth of data available for the use of DES in patients with ST-elevation myocardial infarction, data regarding the performance of DES in non–ST-elevation ACS is restricted to a handful of registries with conflicting data. The aim of this review was to summarize the safety and efficacy of DES in the entire spectrum of ACS.     

Gastrointestinal and biliary stents

Advances in stent design have led to a substantial increase in the use of stents for a variety of malignant and benign strictures in the gastrointestinal tract and biliary system. Whereas early stents were mostly composed of plastic, the majority of contemporary stents are self‐expanding metal stents that are composed of either nitinol or stainless steel. These stents are able to exert an adequate expansile force and, at the same time, are highly flexible and biocompatible. Covered stents have been introduced to minimize tumor ingrowth through the metal mesh but are associated with higher rates for spontaneous migration. This has led to the development of covered stents with uncovered ends and stents with both covered and uncovered layers. Drug‐eluting and biodegradable stents are also likely to become available in the near future. Although stents appear to be the preferred form of palliation for some patients with advanced cancer, many patients will benefit from a multidisciplinary approach that usually includes surgeons and oncologists.     

Drug-eluting stents are associated with similar cardiovascular outcomes when compared to bare metal stents in the setting of acute myocardial infarction

BACKGROUND: Recent randomized trials have demonstrated conflicting results regarding the use of drug-eluting stents (DESs) as compared to bare metal stents (BMSs) in primary percutaneous coronary intervention (PCI). We compared outcomes among patients presenting with acute ST-elevation myocardial infarction (STEMI) who received DES with those who received BMS. METHODS: In-hospital, 30-day, 6-month, and 1-year outcomes of a cohort of 122 patients who underwent primary or facilitated PCI and received a BMS were compared to 122 propensity-matched patients who received a DES. Seventy-two patients received sirolimus-eluting stents, and 50 received paclitaxel-eluting stents. RESULTS: Baseline demographics were similar among groups. One-, 6-, and 12-month outcomes, including reinfarction, death, stent thrombosis, and target vessel revascularization (TVR), were similar among groups. At 1 year, all-cause mortality was 13.3% in the BMS group and 9.2% in the DES group [P=not significant (ns)], recurrent MI was 5.3% in the BMS group vs. 4.4% in the DES group (P=ns), and TVR was 7% in the BMS group vs. 8.7% in the DES group (P=ns). CONCLUSIONS: Our data do not support the general use of DES in the setting of STEMI given similar cardiovascular outcomes among patients receiving BMS or DES, the need for long-term dual antiplatelet therapy with DES, and the possible repercussions of very late stent thrombosis.     

Promise and challenges of bioabsorbable stents.

Despite the development and progression of metallic stents, many concerns still remain because of their permanent nature. Although metallic stents are effective in preventing recoil and late restenosis after coronary angioplasty, they continue to have limitations such as stent thrombosis and mismatch of the stent to the vessel size. Thus, the concept of bioabsorbable stents has emerged as an alternative to permanent metal stents. This review will outline concepts, material designs, preclinical, and initial clinical experimental studies with bioabsorbable stents.     

胰管内支架治疗慢性胰腺炎

目的 探讨胰管内支架引流术治疗慢性胰腺炎的临床疗效。方法 对１４例临床及影像学检查确诊的慢性胰腺炎伴胰管狭窄患者在内镜下进行了胰管内支架引流术，并对术后腹痛缓解率、胃纳、脂肪泻、体重变化及并发症发生率作了近期及远期了随访观察。结果 １４例患者均在内镜下内支架一次性置入成功，支架规格为５～１０Ｆ，术后随访２８～５２０ｄ，平均２１０ｄ，１４例患者术后近期（〈３个月）腹痛缓解率为９２．９％（１３／１４）     

A comparative analysis of major clinical outcomes using drug‐eluting stents versus bare‐metal stents in a large consecutive patient cohort

Objectives : To ascertain the long‐term safety, efficacy, and pattern of use of drug‐eluting stents (DES) in routine clinical practice. Methods : We analyzed a registry of 6,583 consecutive patients undergoing percutaneous coronary intervention (PCI), of whom 2,633 were treated using DES (DES group) and 3,950 were treated using bare‐metal stents (BMS group). Propensity score was used for stratified analysis of outcomes and for matching. Outcomes were total mortality, myocardial infarction (MI), repeat target vessel revascularization (TVR) rates, and risk‐adjusted event‐free survival. Results : Follow‐up time was 6 months to 5.18 years (mean: 3 years). Patients in the DES group were more likely to be diabetic and had use of longer or more stents, treatment of more lesions and of more proximal main vessels. After propensity score matching, the cumulative mortality was 12.85% in the DES group versus 14.14% in the BMS group (P = 0.001). Use of DES reduced the occurrence of MI (5.17% vs.5.83%, P = 0.046), of clinically driven TVR (9.76% vs. 12.28%, P < 0.001) and of the composite endpoint of death/MI/TVR (23.38% vs. 26.07%; P < 0.001). Conclusions : Our risk‐adjusted event‐free survival analysis indicates a prognostic benefit for DES utilization that sustains up to 5 years following PCI. © 2010 Wiley‐Liss, Inc.     

Implantation of migrated biliary stents in the digestive tract

BackgroundBiliary stents constitute an alternative for the palliative treatment of benign or malignant biliary obstruction, biliary strictures, choledocholithiasis, biliary fistulas from lateral lesions of the biliary duct or cystic duct leaks due to slippage of clip closure. Obstruction resulting in cholangitis is common. Proximal migration to the biliary duct or distal migration to the duodenum with subsequent passage per rectum are relatively frequent, but impaction and perforation of the bowel are rare.Case outlinesTwo cases are reported. In one patient a migrated stent impacted in the caecal wall, and in the other the impaction produced a perforation of an adherent small bowel loop. Both patients were treated surgically and made an uneventful recovery.DiscussionBiliary stents migrate in 8–10% of patients and are generally eliminated by natural means. Occasionally they impact and perforate the digestive tract, usually in the duodenum or other fixed areas or in bowel affected by adhesions due to a previous operation. Although endoscopy is the treatment of choice to retrieve them, operation should be performed whenever there is suspicion of perforation of the intestinal wall.     

药物涂层支架晚期血栓形成相关因素的分析

目的 探讨药物涂层支架（DES）晚期血栓形成的相关因素.方法 分别纳入我院2008年1月～2013年1月DES置入术后发生晚期血栓患者30例（血栓组）和置入DES 1年以上未发生支架内血栓患者30例（对照组）,通过64SCT冠状动脉成像观测支架贴壁情况、支架置入部位个数及长度与直径,采集病史分析晚期血栓的危险因素.结果 与对照组相比,血栓组支架贴壁不良发生率（60.0%vs.10.0%）、采用挤压支架技术（crush技术）比例（36.7% vs.13.3%）、分叉病变发生率（43.3% vs.16.7%）、多支架（＞4）置入比例（33.3% vs.0）均较高;支架平均长度较长[（39.2±20）mm vs.（21.7±7）mm],同时支架平均直径也较大[（3.0±0.5）mm vs.（2.5±0.5）mm],差异均有统计学意义（P＜0.05）;另外,血栓组合并左室射血分数减低、糖尿病、肾功能不全及过早停用双重抗血小板治疗的发生率明显高于正常组,有统计学差异（P＜0.05）.结论 DES晚期血栓形成与多种因素有关,包括复杂病变、置入支架过多、过长等,同时还与糖尿病、肾功能不全、抗凝不足等具有相关性.     

Late thrombosis of drug-eluting stents: a meta-analysis of randomized clinical trials

Purpose

Drug-eluting stents are commonly used for percutaneous coronary intervention. Despite excellent clinical efficacy, the association between drug-eluting stents and the risk for late thrombosis remains imprecisely defined.

Methods

We performed a meta-analysis on 14 contemporary clinical trials that randomized 6675 patients to drug-eluting stents (paclitaxel or sirolimus) compared with bare metal stents. Eight of these trials have reported more than a year of clinical follow-up.

Results

The incidence of very late thrombosis (>1 year after the index procedure) was 5.0 events per 1000 drug-eluting stent patients, with no events in bare metal stent patients (risk ratio [RR] = 5.02, 95% confidence interval [CI], 1.29 to 19.52, P = .02). Among sirolimus trials, the incidence of very late thrombosis was 3.6 events per 1000 sirolimus stent patients, with no events in bare metal stent patients (RR = 3.99, 95% CI, .45 to 35.62, P = .22). The median time of late sirolimus stent thrombosis was 15.5 months, whereas with bare metal stents it was 4 months. Among paclitaxel trials, the incidence of very late thrombosis was 5.9 events per 1000 paclitaxel stent patients, with no events in bare metal stent patients (RR = 5.72, 95% CI, 1.08 to 32.45, P = .049). The median time of late paclitaxel stent thrombosis was 18 months, whereas it was 3.5 months in bare metal stent patients.

Conclusions

Although the incidence of very late stent thrombosis more than 1 year after coronary revascularization is low, drug-eluting stents appear to increase the risk for late thrombosis. Although more of this risk was seen with paclitaxel stents, it remains possible that sirolimus stents similarly increase the risk for late thrombosis compared with bare metal stents.     

Endoscopic palliation of unresectable malignant oesophageal strictures with self-expanding metal stents: comparing Ultraflex and Esophacoil stents

BACKGROUND: Two types of self-expanding metal stents to palliate dysphagia in patients with unresectable malignant oesophageal strictures have been compared. METHODS: From February 1996 to October 2000, 50 metal stents (23 covered Ultraflex and 27 Esophacoil) were placed in 50 patients (40 males, mean age: 67+/-12 years, range: 33-100, mean dysphagia score: 3.18+/-0.66) with unresectable malignant oesophageal strictures. Patients were followed until death. A retrospective review has been made of a prospectively collected database. RESULTS: The two groups were comparable as far as concerns degree of dysphagia, location and stricture length. Stent placement was successful in all cases. Covered Ultraflex stent was placed in 2 patients with oesophagobronchial fistula. No procedure-related deaths were seen. Early severe complications occurred in 2 patients (perforation in 1 and tumour bleeding in 1, in the Esophacoil group). Nine patients and 1 patient complained of pain following Esophacoil and Ultraflex stent placement, respectively. Late complications were asymptomatic rupture of distal Esophacoil rings in 2 patients, symptomatic Ultraflex stent migration in 2 and tumour overgrowth in 3 (Esophacoil 1, Ultraflex 2). Mean dysphagia score at 4 weeks after stent placement was 1.9+/-0.77. Mean survival was 177+/-109 days (range: 35-603 days). There were no significant differences in technical success, dysphagia palliation, complications (except chest pain) and survival using the two types of stent. CONCLUSIONS: Self-expanding metal stents are safe with high technical success and achieve satisfactory long-term palliation for dysphagia. The covered Ultraflex and Esophacoil stents are equally effective.     

Radial force of coronary stents: A comparative analysis

High radial force has become an essential feature of new coronary stents. These stents are expected to exhibit sufficient radial force and minimum radial recoil when deployed in atheromatous lesions of various morphologies. The aim of this study was to compare the radial force of 17 coronary stents in vitro (Anglodynamics, ACS Multilink, AVE Micro II and GFX, Bard XT, Biocompatibles PC, Cook GR II, Cordis Crossflex, Hexacath Freedom, Johnson & Johnson PS 153'PS 154, and Crown, Medtronic Wiktor and BeStent BEL-15, Saint-Côme SC 1616, Scimed Nir 7 and 9). Two in vitro mechanical tests were performed to assess the stent radial force. The first test measured the deformation of coronary stents in a V-stand by using a deformation controlled by a dynamometer based on a longitudinal generatrix. The precision was of 1 micron. This comparative test highlighted the appreciable variation in behavior of the range of tested stents in terms of resistance to local compression. The line graphs obtained show a very small (and in some cases nonexistent) purely elastic behavior area in the stents, with this result reflecting a small (<0.4 Newtons) range of forces applied to all stents. Above this value, the stents did not return to their size before compression and the line graph remains approximately linear for a long period. It was therefore possible to distinguish between two families of stents on the basis of the presence or absence of this elastic area. In the second test, the stent was deployed in a 3.0-mm elastic tube and a pressure gradient created between the interior and exterior of the tube. The precision was of 50 microns. A typical line graph of the pressure-diameter relationship was recognizable for a given stent. No difference in behavior between the different coronary stents was noted up to 0.3 × 10⁵ Pa; subsequently, after 0.3 × 10⁵ Pa, sizable deformation differences were visible between the least resistant stent, the BeStent BEL-15, and the most resistant stent, the Crossflex. Cathet. Cardiovasc. Intervent. 46:380–391, 1999. © 1999 Wiley-Liss, Inc.     

A propensity score matched analysis to determine if second-generation drug-eluting stents outperform first-generation drug-eluting stents in a complex patient population

Background

Drug-eluting stents (DES) are routinely used in complex patients, but the impact of 1st- versus 2nd-generation DES on clinical outcomes has not been well described. This study aimed to assess the efficacy and safety of 2nd-generation (everolimus-eluting) DES compared to 1st-generation (sirolimus- and paclitaxel-eluting) DES in a selected, higher-risk population with complex clinical and angiographic features.

Methods

The study included 5693 consecutive patients with the presence of ≥ 1 predefined complex clinical and angiographic characteristic treated with either generation DES. Using propensity score matching, the clinical outcomes of 1076 patients treated with 2nd-generation DES were compared with the outcomes of a matched population treated with 1st-generation DES over 1-year follow-up.

Results

After matching, baseline clinical and angiographic characteristics were similar between groups. At 1-year follow-up, the rate of major adverse cardiac events was 9.4% with 2nd-generation DES and 11.3% with 1st-generation DES (p = 0.16). There were no significant differences in the rates of death (3.2 vs. 4.0%, p = 0.30), myocardial infarction (1.6 vs. 1.3%, p = 0.57), target vessel revascularization (5.9 vs. 7.3%, p = 0.17) or target lesion revascularization (4.4 vs. 5.0%, p = 0.50). Definite stent thrombosis was less frequent with 2nd-generation DES (0.1 vs. 0.8%, p = 0.011), as was definite or probable stent thrombosis (0.7 vs. 1.6%, p = 0.040).

Conclusion

In this propensity score matched patient population with complex features undergoing percutaneous coronary intervention, the use of 2nd-generation DES was associated with lower rates of stent thrombosis, and similar 1-year major adverse cardiac events compared to 1st-generation DES.