Late coronary stent thrombosis: early vs. late stent thrombosis in the stent era.

The incidence of coronary stent thrombosis is < 1%-2% in recent studies, with the highest-risk period considered to be the first 30 days following stent implantation. Recently, stent thrombosis after 30 days has been reported in patients undergoing brachytherapy with stenting. We reviewed the incidence of stent thrombosis causing myocardial infarction in nonbrachytherapy patients at our institution between 1 January 1996 and 30 November 1999. A case control methodology was employed with a 1:3 ratio of stent thrombosis to control patients. Of 1,191 patients undergoing coronary stenting, acute (< 24 hr) plus subacute (1-30 days) stent thrombosis occurred in 0.92% (11 of 1,191 patients). A further 0.76% (9 of 1,191 patients) developed late stent thrombosis after 30 days. There were no clinical or angiographic features at the time of the initial procedure that were associated with stent thrombosis as an entire group compared with control group, but early (acute and subacute) stent thrombosis patients had a smaller final stent minimal lumen diameter and longer stent length compared with patients who had late stent thrombosis or controls. Late stent thrombosis occurs in nonbrachytherapy patients and is almost as frequent as early stent thrombosis. Further studies are required to determine whether longer-term poststent pharmacological treatment may decrease or prevent this complication.     

药物洗脱支架断裂的影像认识

目的借助冠状动脉造影和血管内超声的影像资料,确定支架断裂的发生和类型。方法回顾性分析北京大学人民医院2 021例冠状动脉造影和183例血管内超声（IVUS）影像资料。结果共发现3例患者的6处支架断裂,其中2例经IVUS证实。3例支架断裂均发生在西罗莫司药物洗脱支架,且均发生在冠状动脉介入术后1年以内。冠状动脉造影证实4处支架断裂为完全断裂伴断裂处支架移位。IVUS证实3处支架断裂为完全断裂,2处为部分断裂;1处断裂靠近支架重叠处;1处支架断裂伴有血管瘤形成。结论冠状动脉造影和IVUS可以帮助确定支架断裂的诊断。     

Symptomatic stent cast

Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.     

Impact of asymmetric stent expansion on neointimal hyperplasia following sirolimus-eluting stent implantation

To assess whether asymmetric stent expansion affects suppression of neointimal hyperplasia after sirolimus-eluting stent implantation, 64 patients in the SIRolImUS-coated Bx Velocity stent trial who underwent single 18-mm stent implantation and 3-dimensional intravascular ultrasonography at 8-month follow-up were enrolled. To assess the longitudinal stent asymmetric expansion, 2 cross sections with a maximal/minimal stent area were chosen in each patient. To assess for tomographic stent asymmetric expansion, stent eccentricity was determined by dividing the minimum stent diameter by the maximum stent diameter. At the 2 cross sections with a maximal/minimal stent area, a sirolimus-eluting stent reduced neointimal hyperplasia significantly with no interaction between the treatment and stent areas. A sirolimus-eluting stent also significantly reduced neointimal hyperplasia in the concentric and eccentric stent groups.     

Late stent thrombosis after implantation of a sirolimus-eluting stent.

Late stent thrombosis in the era of routine high-pressure stent deployment and combined antiplatelet therapy with thienopyridines and aspirin has become a rare but feared complication. We describe a patient with acute myocardial infarction due to late stent thrombosis 6 weeks after deployment of a sirolimus-eluting stent and 2 weeks after the discontinuation of clopidogrel. This is the first report of late thrombosis of a sirolimus-eluting stent.     

硅酮支架与覆膜金属支架并发症的对比观察

目的对照观察硅酮支架与Z型不锈钢覆膜金属支架置入后的并发症,为临床支架的选择提供参考。方法 2014年4月至2015年2月因气道狭窄或气道瘘65例患者置入硅酮支架,77例患者置入覆膜金属支架,术后定期支气管镜检查,观察2个月内两组病例的主要并发症。结果硅酮支架组置入分叉型支架45例、沙漏状支架7例、直筒型支架13例;覆膜支架组置入分叉型支架70例、直筒型支架7例。两组并发症比较:痰液潴留硅酮支架50例(76.9%)、覆膜支架61例(79.2%),相差不显著(P0.05);肉芽增生硅酮支架39例(60.0%)、覆膜支架69例(89.6%),相差显著(P0.01);支架移位:分叉型及沙漏状支架均无移位,直筒型支架移位硅酮支架2例(15.3%)、覆膜支架6例(85.7%),相差显著(P0.01);顽固性咳嗽硅酮支架4例(6.1%)、覆膜支架7例(9.0%),相差不显著(P0.05)。因肉芽增生明显经处理效果差,9例覆膜支架取出支架,硅酮支架未因肉芽增生取出支架。结论硅酮支架与覆膜支架比较,硅酮致肉芽增生较轻,其直筒型移位较少,建议对需长期放置支架的患者,优先考虑硅酮支架。     

Sirolimus-eluting stent implantation outside a previous stent

With device improvements, more total occlusions have been crossed with a guidewire and balloon. However, true intraluminal/intrastent passage is not always accessed, which is not apparent on coronary angiography. In this study, using intravascular ultrasound as well as computed tomography, we demonstrated a crushed stent previously implanted outside the sirolimus-eluting stent, which resulted from subintimal (outside the stent) passage of a guidewire.     

Very late stent fracture associated with a sirolimus-eluting stent

Late stent thrombosis (>1 year after implantation) is a recognised complication involving drug-eluting stents. Stent fracture is increasingly being reported as a complication of drug-eluting stent, and in particular sirolimus-eluting stent use. We report the case of very late sirolimus-eluting stent fracture resulting in an acute coronary syndrome. This case report highlights the need for greater awareness and post-marketing surveillance to detect a potential mechanism for late stent thrombosis in the drug-eluting stent era.     

Stenting the stent

BACKGROUND: Stents are constructed with predefined radial strength which, on occasion, may be insufficient to support a resistant lesion. METHODS: We prospectively assessed the need for, and safety of, implanting a second stent within the first, during the index procedure, in a consecutive series of 500 patients undergoing percutaneous coronary intervention (PCI) by a single operator in the period 1998 2001. The indication was a lesion that appeared angiographically suboptimal after full balloon/stent expansion to high pressure with appropriate sizing. Visible thrombus was an exclusion. Stents were slotted tubes or ring designs whenever possible. Clinical follow-up was > 1 year and angiographic re-study was performed when indicated. RESULTS: We identified 18 patients/lesions (3.6%) that required implantation of a stent within a stent. The appearance was due to tissue/stent prolapse in 72%, edge dissection in 17%, narrow stent inflow/outflow in 5.5% and inadvertent stent detachment in 5.5%. There were no lesion-related acute or in-hospital complications. There was no late thrombosis or death. Follow-up was 21 10 months, and revealed 11% target lesion revascularization, of which half were at the site of stent overlap. CONCLUSION: Stenting the stent, where extra support is required, is safe and effective.     

Very late stent thrombosis in late stent malapposition after sirolimus-eluting stent implantation

Late stent malapposition (LSM) has been demonstrated to be more common after drug-eluting stent (DES) implantation than after bare-metal stent (BMS) implantation. To date, this unusual intravascular ultrasonic finding after DES implantation, however, has not received enough attention, because previous studies suggested few adverse clinical sequelae from LSM. We present a case of angiographically-confirmed very late stent thrombosis (ST) in LSM after elective implantation of sirolimus-eluting stents. In this 32-year-old male patient, very late ST occurred at 29 months after DES implantation and at 20 months after the identification of LSM. Although this patient had received sufficient dual antiplatelet therapy with aspirin and clopidogrel for more than 1 year, he suffered from ST shortly after the discontinuation of clopidogrel. Thus, patients with LSM may pose a significant risk for very late ST after discontinuation of dual antiplatelet therapy. The findings suggest that dual antiplatelet therapy should be further prolonged in patients with LSM.     

Microwave coagulation versus insertion of a second stent for occluded biliary metal stent.

BACKGROUND/AIMS: There is no consensus regarding optimal management of self-expandable metallic stent occlusion. We investigated the efficacy of microwave coagulation therapy for recanalization as compared to second stent placement. METHODOLOGY: Sixty patients with malignant obstruction of the common bile duct were treated with metal stent placement from January 1992 to July 1999. Of these, 13 patients subsequently developed stent occlusion due to tumor ingrowth. We compared stent patency and patient survival rates after microwave coagulation to those after insertion of a second stent. The influence of the duration of patency of the first stent on the second stent patency was also evaluated. RESULTS: Of the 13 patients with stent occlusion, 7 were treated with microwave coagulation therapy, and 6 with insertion of a second metal stent. In all cases, occluded stents were successfully recanalized without any complications. There was no significant difference in duration of first stent patency between the two groups. The median duration of second stent patency was prolonged in microwave-treated patients (152 days vs. 104 days, P > 0.05). The median duration of patient survival after last recanalizing procedure was also prolonged in microwave-treated patients (131 days vs. 78 days, P > 0.05). Microwave energy did not induce destruction of the stent filament. CONCLUSIONS: Microwave coagulation did not offer significantly longer duration of stent patency and patient survival compared to insertion of a second metal stent. However, this procedure is safe, feasible, and certainly as good as a second stent placement. It may be an alternative to insertion of a second stent within the occluded stent.     

Dislodged and mechanically distorted stent stuck within a previously implanted drug-eluting stent

Coronary stent loss during percutaneous coronary intervention is rare and is often associated with significant morbidity. Several retrieval techniques, overlying stent deployment and crushing, and surgical removal can be used to deal with a stent lost in the coronary system. We successfully treated a dislodged and mechanically distorted coil stent stuck within a previously implanted drug-eluting stent (DES) by stent-crush technique. This case might provide insight into the mechanisms responsible for the longitudinal fragility of cobalt alloy and coil-structure stents and stent fracture of DES. In the DES era, careful attention should be paid to such complications when attempting to deliver a stent to a distal vessel through a pre-existing DES.     

Diagnosis and treatment of coronary stent entanglement complicated by extreme stent distortion

A 2.5 x 32 mm Taxus Libert e stent was deployed at high pressure in the proximal right coronary artery (RCA) of a 71-year-old male patient, but the distal part of the lesion remained uncovered. A second stent (Driver 2.5 x 12 mm) could not be advanced through the first one and was withdrawn. The pullback traction resulted in dislodgement of the stent from its delivery balloon. Fluoroscopic examination suggested that the missing stent had traveled to the ascending aorta. Transesophageal echocardiography disclosed a dense, linear, mobile structure in the ascending aorta arising from the right coronary ostium. A 64-multislice computed tomographic scan revealed that both stents were entangled, with the first stent (Taxus 32 mm) elongated (approximately 90 mm in length), and the second one (Driver 12 mm) attached to the tail of the Taxus stent in the aorta. Stent retrieval was performed with a 15 mm snare loop catheter through a 7 Fr femoral sheath. Examination of the retrieved material revealed elongation of the Taxus stent entangled with the Driver stent. This case illustrates the potential for serious complications derived from stent entanglement, even with modern stent platforms, and how integrating noninvasive imaging modalities can provide crucial information regarding the cause of the complication and its solution.     

Very late stent thrombosis associated with multiple stent fractures and peri-stent aneurysm formation after sirolimus-eluting stent implantation.

Previous randomized trials have shown that drug-eluting stents (DES) are superior to bare-metal stents in reducing the need for target lesion revascularization, but safety issues with DES have recently been raised. We report a rare case of very late stent thrombosis 35 months after sirolimus-eluting stent implantation associated with delayed 5-segment stent fractures and peri-stent aneurysm formation.     

Stent-grafts for the treatment of TIPS dysfunction:Fluency stent vs Wallgraft stent

AIM:To evaluate the clinical efficacy of an expanded polytetrafluoro-ethylene-covered Fluency stent compared with that of a polyethylene terephthalate-covered Wallgraft stent for the management of transjugular intrahepatic portosystemic shunt(TIPS)dysfunction.METHODS:A retrospective review of patients who underwent TIPS revision with stent-grafts between May 2007 and June 2011 was conducted.The patients were divided into two groups according to the stentgrafts implanted:the Fluency stent(Bard Incorporated,Karlsruhe,Germany)and the Wallgraft stent(Boston Scientific,Galway,Ireland).The primary patency rates were calculated and compared using the Kaplan-Meier method.RESULTS:A total of 73 patients were evaluated in this study:33 with Fluency stents and 40 with Wallgraft stents.The primary patency rates at 12 and 24 mo were 91% and 85%,respectively,in the Fluency stent group and 78% and 63%,respectively,in the Wallgraft stent group.The primary shunt patency rates after TIPS revision were significantly better with the Fluency stent than with the Wallgraft stent(P = 0.033).CONCLUSION:TIPS revision with the Fluency stent has higher medium-term patency rates than that with the Wallgraft stent.     

Recurrent very late stent thrombosis after bare-metal stent implantation.

Very late bare-metal stent thrombosis occurring beyond 1 year after stenting is uncommon. Although much attention has been paid for late stent thrombosis, long-term outcome of patients who developed late stent thrombosis is not clear. We report a case of recurrent very late stent thrombosis after bare-metal stent implantation.     

药物洗脱支架置人术后断裂导致支架内再狭窄的临床分析

目的 探讨药物洗脱支架(DES)置入术后支架断裂与再狭窄的关系及支架断裂的特点.方法 回顾性分析冠状动脉支架置人术后行冠状动脉造影复查的536例患者,实验分为DES组(N=397)和裸金属支架(BMS)组(n=139).分析支架置入术前、术后及复查时的冠状动脉造影图像,找出支架内再狭窄和支架断裂的病例,分析支架断裂和再狭窄的关系以及支架断裂的病变特征及形态特征.结果 DES组和BMS组再狭窄分别为31例和30例(P＜0.01),其中5例发生支架断裂,断裂的支架均为DES,BMS组未见支架断裂,两组差异有统计学意义(P＜0.05).发生支架断裂的5例靶病变均为扭曲病变,支架断裂均发生在血管扭曲成角处.结论 支架断裂是DES置入术后发生再狭窄的原因之一,扭曲病变置入长的DES后可能容易发生支架断裂.     

Recurrence of late-acquired incomplete stent apposition following sirolimus-eluting stent implantation

Stent thrombosis has been recognized as a potentially critical complication in percutaneous coronary intervention. In the bare-metal stent era, stent thrombosis was considered to be an acute or subacute event, occurring within 1 month after stent implantation. Recently, late or very late stent thrombosis after drug-eluting stent implantation has been brought into focus; however, the mechanism underlying this potentially fatal event is largely unknown. We report a case of critical late thrombosis 2 years after sirolimus-eluting stent implantation. Detailed serial intravascular ultrasound analyses revealed that late-acquired incomplete stent apposition, accompanied by extensive positive vascular remodeling, was involved in the pathogenesis of the nearly fatal event described in this case.     

Assessment of optimum stent deployment by stent boost imaging: comparison with intravascular ultrasound

Stent boost (SB) imaging is an enhancement of the radiologic edge of the stent by digital management of regular X-ray images. The purpose of the present study was to validate SB imaging by comparison with the anatomical standard using intravascular ultrasound (IVUS). We investigated SB and IVUS after stent implantation in 68 arteries in 60 patients. Based on those findings, we added high-pressure dilatation in four patients and another stent implantation in four patients. We defined the SB criteria for adequate stent deployment as: complete stent expansion, stent minimum diameter ≥70% of reference diameter, and stent minimum diameter ≥2.0 mm; and IVUS criteria for adequate stent deployment as: minimal stent area ≥5.0 mm². If the reference vessel was <2.8 mm, adequate stent deployment was defined as minimum stent area ≥4.5 mm². IVUS findings indicated inadequate stent deployment in 21/72 observations (29%). Seven SB images showed inadequate stent expansion. SB predicted inadequate findings of IVUS with 100% specificity, 33% sensitivity, and 81% agreement. Although the sensitivity of SB image for adequate stent deployment is low, the specificity is sufficiently high for it to be the first-line for monitoring just after stent implantation in centers where IVUS is not used routinely.     

Long-term follow-up after angiographically successful coronary stenting: direct stent versus conventional stent implantation

The purpose of the study was to compare the impacts of angiographically successful direct stent implantation and conventional stent implantation (stent implantation following predilatation) on long-term major cardiac events. The authors prospectively studied 40 patients who had successful direct stent implantation and 46 patients who had successful conventional stent implantation. The end-point of the study was defined as the occurrence of a major cardiac event, including recurrent angina, acute myocardial infarction, death, and target vessel revascularization. The demographic and clinical characteristics of the study groups were similar, except the indication of percutaneous angioplasty, which was more frequently unstable angina in the conventional stent group (63% vs 38%, P: 0.03). Procedural minor complications were more frequent in conventional stent implantation, and there was also a positive correlation between the conventional stent implantation and procedural minor complications (r = 0.231, P: 0.03), and postprocedural troponin elevation (r = 0.221, P: 0.04). The incidences of major cardiac events including recurrent angina, acute myocardial infarction, death, death or myocardial infarction, and target vessel revascularization were not different between the study groups during the long-term follow-up period (21 +/- 7.1 months for direct stent group and 20 +/- 7.5 months for conventional stent group). Overall end-points occurred in 9 patients (22%) in the direct stent group and in 9 patients (19%) in the conventional stent group. Kaplan-Meier survival analysis showed that there was no difference in event-free survival between the patients treated with direct stent implantation and conventional stent implantation (log-rank: 1.52, P = 0.21). Two-vessel intervention and hypertension were found to be related with long-term major cardiac events (r = 0.214, P: 0.048, r = 0.206, P: 0.04, respectively). In addition to the procedural advantages, direct stent implantation may also provide comparable results with conventional stent implantation concerning the late cardiac events following successful percutaneous coronary angioplasty.