Sirolimus‐eluting stent fracture detection by three‐dimensional optical coherence tomography

Stent fracture has emerged as a complication of drug‐eluting stent and is now recognized as contributing to in‐stent restenosis and possibly stent thrombosis. Although optical coherence tomography (OCT) can detect stent fractures in the absence of circumference struts, it is challenging to visualize stent fractures with only cross‐sectional OCT images. We describe two cases of restenosis with stent fracture detected by a novel three‐dimensional OCT image reconstruction technique. This technique allows identification of a single stent fracture even in the absence of angiographic signs. © 2011 Wiley Periodicals, Inc.     

Drug‐eluting stent fracture: Incidence,contributing factors,and clinical implications

Stent fracture has been observed in noncoronary vessels, especially in the superficial femoral and popliteal arteries and with bare metal stents in saphenous vein grafts of coronary arteries. Since the introduction of drug‐eluting stents, stent fractures have also been reported in small studies and case reports. We reviewed these publications to assess what is known regarding the incidence, contributing factors, and clinical implications of drug‐eluting stent fracture in coronary arteries. The reported rate of drug‐eluting stent fracture in coronary arteries ranges from 1 to 8%, although much of the available literature is derived from single‐center studies that are heterogeneous in their study methods. A higher risk of stent fracture may be associated with the right coronary artery location, excessive tortuosity or angulation of the vessel, overlapping stents, and longer stents. The closed‐cell design of the Cypher stent has been associated with increased rigidity that may increase the risk of stent fracture, although these studies did not assess the overall outcomes between the Cypher and Taxus stents in a head‐to‐head comparison. Stent fracture has been shown by most studies to be associated with a statistically increased incidence of focal in‐stent restenosis, and some have shown an increased risk of target lesion revascularization. Other complications observed with stent fracture include stent thrombosis, coronary aneurysms, myocardial infarction, and sudden death. © 2009 Wiley‐Liss, Inc.     

Placement of “biliary” stents in saphenous vein coronary bypass grafts

Angioplasty of coronary saphenous vein grafts has been associated with less favorable results than in native coronary arteries owing to a higher acute complication rate and an increased incidence of restenosis. We placed 16 nonarticulated balloon expandable stainless steel “biliary” stents at the sites of 13 stenotic or occluded aortocoronary saphenous vein graft lesions in 11 patients. All of the lesions were stented successfully. There were no instances of stent thrombosis or stent embolism. The percent diameter stenosis was reduced from 85.5 ± 14.1% to 3.5 ± 4.4% (p < .001), and the minimal lumen diameter of the lesion increased from 0.7 ± 0.7 mm at baseline to 3.7 ± 0.2 mm (p < .001) after stent placement. We conclude that this noncoronary stent appears to be safe and effective for treating saphenous vein coronary bypass grafts. The high procedural success rate and excellent anglographic results are very encouraging, while the restenosis rates remain to be determined. © 1993 Wiiey-Liss, Inc.     

Preventive effects of the heparin-coated stent on restenosis in the porcine model.

The coronary stent reduces acute coronary arterial occlusion and late restenosis during and after coronary intervention. However, stent thrombosis and restenosis are still major limitations in the widespread use of the coronary stent. Local drug delivery using the heparin-coated stent may be a new approach, which reduces the incidence of stent thrombosis and restenosis. In order to evaluate the effects of the heparin-coated stent on stent restenosis, heparin-coated stents were compared with control stents in a porcine coronary stent restenosis model. Stent overdilation injury (stent:artery = 1.3:1.0) was performed with bare Wiktor stents (group I, n = 10) and heparin-coated Wiktor stents (group II, n = 20; HEPAMED, Medtronics) in porcine coronary arteries. Follow-up quantitative coronary angiography (QCA) was performed at 4 weeks after stenting, and histo-pathologic assessments of stented porcine coronary arteries were compared in both groups. On QCA, percent diameter stenosis was significantly higher in group I than in group II (16.3% +/- 6.62% vs. 9.6% +/- 5.06%, P < 0.05). The injury score of stented porcine coronary arteries was the same in both groups (1. 26 +/- 0.23 vs. 1.20 +/- 0.22). The area of pathologic stenosis of the stented arteries was higher in group I than in group II (41.6% +/- 12.5% vs. 27.1% +/- 9.9%, P < 0.005). The neointimal area was higher in group I than in group II (4.58 +/- 1.41 mm(2) vs. 2.57 +/- 1.07 mm(2), P < 0.05). By immunohistochemistry, the proliferating cell nuclear antigen (PCNA) index was higher in group I compared with group II (11.2% +/- 6.75% vs. 6.3% +/- 4.14%, P < 0.05). The heparin-coated stent is effective in the prevention of late coronary stent restenosis in a porcine coronary stent restenosis model. This may be related to the inhibition of neointimal cell proliferation.     

Multiple Stent Fractures After Everolimus-Eluting Stent Implantation Causing Acute Myocardial Infarction: A Case Report

Stent fracture is an uncommon complication of drug-eluting stent implantation, but it has a clinical significance because of its potential association with adverse cardiac events such as in-stent restenosis, target lesion revascularization, and stent thrombosis. Multiple stent fractures account for a small proportion, but they may lead to more serious complications. Newer generation drug-eluting stents are designed for improved safety and efficacy compared with early generation drug-eluting stents. Multiple stent fractures after newer generation drug-eluting stent implantation are a rare case.We report a case of 25-year-old male who presented with acute myocardial infarction caused by multiple stent fractures after everolimus-eluting stents implantation and was treated by balloon angioplasty.Physicians should be aware of the possibility of multiple stent fractures even after newer generation drug-eluting stent implantation.     

Late stent thrombosis in brachytherapy: the role of long-term antiplatelet therapy

Advances in percutaneous coronary intervention (PCI) have emerged in the past decade. Stenting has improved upon the limitations of angioplasty, acute vessel closure and restenosis by providing mechanical vascular support, resulting in sustained clinical and angiographic benefit. This has led to greater utilization of the technique, although it is associated with a significant incidence of in-stent restenosis. Neointimal hyperplasia is the pathophysiologic process that leads to in-stent restenosis. Brachytherapy can be effective in reducing the occurrence of this process. Unfortunately, brachytherapy trials have identified the phenomenon of late stent thrombosis as a potentially serious complication of this procedure. Late stent thrombosis is thrombosis that occurs > 30 days after PCI. The risk of thrombosis is increased in patients receiving a new stent in addition to brachytherapy. It also appears to be increased when adjunctive antiplatelet therapy with ticlopidine or clopidogrel is discontinued early. Strategies to prevent late stent thrombosis include the prolonged use of combination antiplatelet therapy in addition to limited placement of new stents in patients treated with brachytherapy for in-stent restenosis.     

Stent thrombosis due to stent fracture in heavily calcified right coronary artery

Coronary stent fracture is an often unrecognized cause of target vessel failure, however, it has been reported more frequently in the drug-eluting stent era. Clinical presentation of stent fracture may range from benign in-stent restenosis to potentially fatal acute stent thrombosis. Interventional treatment of stent thrombosis can be carried out by high pressure balloon dilatation or second stent implantation into the stented segment after thrombus aspiration. Intravascular ultrasound is mandatory in order to exclude mechanical problems in the background of the stent thrombosis and to achieve good final stent apposition and expansion. We report on a stent fracture induced stent thrombosis occurring in a highly calcified proximal right coronary artery. (Treated previously with rotational atherectomy in the middle part, but not in the aortoostial location.) Our case emphasizes the importance of opitimal plaque modification with rotational atherectomy in a calcified aorto-ostial segment of right coronary artery to prevent long term complications such as stent thrombosis or restenosis due to stent fracture.     

Coronary Stent Fracture: A Recently Appreciated Phenomenon with Clinical Relevance

In the stent era, in addition to restenosis, there are many important consequences deserving more attention. Firstly described in peripheral vascular interventions, it took several years for stent fracture to be known as an appreciable complication of coronary intervention. Especially with the introduction of drug eluting stents and the use of coronary stents in more complex cases, its prevalence has raised and new data have been published concerning its mechanism, predictors, diagnosis, clinical course and treatments. This review will discuss the available literature about stent fracture.     

A case of early drug-eluting stent fracture

Although stent fracture following femoro-popliteal intervention is well recognized, coronary stent fracture represents an underrecognized entity. Its incidence is low but it represents an important clinical entity as it may complicate with stent thrombosis causing acute coronary syndromes, or may predispose to instent restenosis. Although coronary stent fracture may involve both bare metal stents (BMS) and drug-eluting stents (DES), a recent analysis of the literature indicates that reports of stent fracture have increased since DES was introduced. Furthermore, chronic stretch at specific vessel sites as bends may lead to late occurrence of fracture. We present the case of a patient with a non-ST-segment elevation acute coronary syndrome caused by the early fracture of an everolimus-eluting stent (Xience?) implanted only three days before.     

Acute coronary syndrome due to early multiple and complete fractures in sirolimus‐eluting stent: A case report and brief literature review

Despite drug eluting stents (DES), as compared to bare metal stents, have reduced in‐stent restenosis, complex and long lesions remains a challenge for interventional cardiologist. Their treatment is often associated with an unfavorable outcome, related to in‐stent restenosis, stent thrombosis, and target lesion revascularization. These complications may derive from the contact between metallic structures and coronary artery endothelium, and consequent overexpression of platelet activating factors, growth factors, and inflammatory cytokines. Recently, an additional mechanism has emerged as new cause of these complications: “stent fracture.” Several factors are involved in this phenomenon including material and stent platform, target vessel features, stent implantation technique, and implant duration. We reported a case of 69 years old man with rare early and complex DES fractures on right coronary that caused acute coronary syndrome 36 hr after a previous percutaneous coronary intervention.© 2012 Wiley Periodicals, Inc.     

Safety and efficacy of angiography-guided stent placement in small native coronary arteries of < 3.0 mm in diameter

Background and hypothesis: Increased operator experience, greater insight in stent deployment techniques, and improved poststent medication regimen have significantly reduced the risk of thrombotic stent closure following stent placement in large coronary arteries ( 3.0 mm in diameter). Whether equally favorable results are afforded by stent placement in small vessels (> 3.0 mm), however, remains unclear. Accordingly, the aim of this study was the specific examination of the risk of stent placement in small native coronary vessels, using stent deployment technique consisting of supplementary dilatations with larger balloons or high-pressure inflations, and aggressive aspirin-ticlopidine and short-term oral anticoagulation poststent therapy. Methods: Forty-seven balloon-expandable stents (20 Gianturco-Roubin, 21 NIR, 6 Palmaz-Schatz) were successfully implanted without intravascular guidance in 45 native coronary arteries (mean reference diameter of 2.5 mm) in 44 consecutive patients (31 men, 13 women), the majority of whom (87%) were stented for the treatment of failed or suboptimal balloon angioplasty outcome. Results: Successful stent placement reduced the lesion diameter stenosis from 91 ± 9% to 3 ± 7% (p = 0.0001). There were no early stent thrombosis or major cardiovascular events prior to hospital discharge. During a 12-month follow-up period, most patients remained symptomatically improved and no myocardial infarction, stroke, or death was observed. Five-month angiographic reassessment revealed an in-stent restenosis rate of 41%, which was higher in vessels 2.5 mm in size (47 vs. 33% for vessels > 2.5 mm, p = 0.2747). Conclusions: In selected patients with small native coronary vessels < 3.0 mm in diameter, angiography-guided optimal stent placement is associated with a low risk of stent thrombosis and bleeding complications. However, the in-stent restenosis rate is high with the stents used in this study.     

Fracture of Zotarolimus-Eluting Stent after Implantation

Drug-eluting stents were developed and approved for the reduction of in-stent restenosis. However, restenosis still occurs, and stent fracture is suggested as a cause of restenosis after implantation. Although sirolimus-eluting stents are considered to carry a high risk of fracture, the risk is also present with other drug-eluting stents. Herein, we report the case of a 78-year-old woman who received a zotarolimus-eluting stent for a bifurcation lesion of the left anterior descending coronary artery. Ten months later, she underwent coronary angiography due to angina. The angiogram revealed in-stent restenosis, with a grade IV stent fracture. After percutaneous coronary angioplasty, the patient''s clinical symptoms improved.Key words: Blood vessel prosthesis implantation/instrumentation, coronary restenosis/diagnosis/etiology/prevention & control, drug-eluting stents, drug implants/adverse effects, prosthesis failure, retreatment, stents/adverse effectsAlthough drug-eluting stents (DESs) reduce in-stent restenosis, important complications of coronary DESs are restenosis and thrombosis. Stent fractures have also been reported¹ and are considered to be possible causes of restenosis² within DESs. The sirolimus-eluting stent is reported to be prone to fracture.³ For example, there is the Cypher® stent (Cordis Corporation, a Johnson & Johnson company; Miami Lakes, Fla)—made of balloon-expandable stainless steel, a durable copolymer mixture of polyethylene-covinyl acetate and poly-u-butyl methacrylate, and sirolimus, which is a Gap 1 (G1) cell-cycle inhibitor.⁴ Other DESs are also considered to be at risk of fracture. One, the Endeavor® Sprint Zotarolimus-Eluting Coronary Stent System (Medtronic, Inc.; Minneapolis, Minn), uses a cobalt chromium stent platform; a durable, antithrombotic, phosphorylcholine-encapsulated coating; and another G1 cell-cycle inhibitor, zotarolimus.⁴ Here, we report the case of a woman who was treated with a zotarolimus-eluting stent that subsequently fractured.     

药物促进冠脉支架置入术后血管再内皮化

经皮冠状动脉球囊扩张和支架置入术是目前治疗冠心病的重要手段。早期的冠脉支架为金属裸支架（BMS）,由于BMS置入术后冠状动脉的再狭窄率较高,药物涂层支架（DES）应运而生。DES通过抑制血管内膜的增生降低支架置入术后再狭窄,但同时也带来了内皮延迟愈合,内皮化延迟是支架内晚期血栓发生的基础,晚期血栓常可带来非常严重的后果。目前已知很多药物可促进血管再内皮化,预防晚期血栓的发生。本文将重点就晚期血栓发生的机制、常见促进再内皮化的药物如粒细胞集落刺激因子、过氧化物酶体增殖物激活受体激动剂、促红细胞生成素、雌激素、他汀的机制及研究现状进行综述。     

Stent fracture associated with drug‐eluting stents: Clinical characteristics and implications

Objective : To evaluate the clinical characteristics and implications of stent fracture in drug‐eluting stents. Background : Approximately 2.5 million drug‐eluting stents are implanted every year worldwide. In 10 randomized controlled trials involving 2,602 patients, no incidence of stent fracture was recognized or reported. Methods : From April 2003 to December 2005, 2,728 patients underwent drug‐eluting stenting. The angiograms of all 530 patients who underwent repeat angiography were analyzed to identify the presence of stent fracture. We then documented the incidence of adverse events associated with drug‐eluting stent fracture and systematically analyzed the clinical, procedural, and structural factors, which might predispose to stent fracture. Results : Stent fracture was identified in 10 patients. None of these fractures were detectable at the time of stent placement. The median time interval from stent implantation to detection of fracture at repeat angiography was 226 days (range, 7–620 days). Adverse clinical outcomes associated with stent fracture occurred in 7 patients (6 patients had binary restenosis and 1 patient had stent thrombosis), all necessitating repeat intervention. Analysis of potential predisposing clinical, procedural, and structural factors revealed that 4 patients had excessive tortuosity in the proximal segment, and overlapping stents were used in 5 cases. All fractures occurred in sirolimus‐eluting stents. Conclusions : Stent fracture may represent a new potential mechanism of restenosis and stent thrombosis in drug‐eluting stents. Predisposing clinical and procedural factors may be vessel tortuosity and use of overlapping stents. The most important predisposing factor, however, may be stent structure, since all fractures occurred in sirolimus‐eluting stents. © 2006 Wiley‐Liss, Inc.     

Delayed strut fracture of sirolimus-eluting stent: a significant problem or an occasional observation?

In-stent restenosis after implantation of sirolimus-eluting stents (SES) still occur in some cases and stent fracture was recently suggested as a new potential mechanism of restenosis. We report a case of delayed stent strut fracture after percutaneous coronary intervention with SES. Until now, three cases regarding Cypher stent fracture have been reported in the literature. Further investigation should be performed to elucidate the clinical significance of stent fractures of SES.     

A completely fractured zotarolimus‐eluting stent in an aortocoronary saphenous vein bypass graft

Drug‐eluting stents (DES) have significantly improved the rate of target vessel revascularization in comparison with bare metal stents. DES fracture was not reported in multicenter randomized clinical trials, but several case reports of DES fracture have been published, mostly with sirolimus‐eluting stents. DES fracture is associated with stent restenosis and thrombosis. We report a zotarolimus‐eluting stent fracture in an aortocoronary saphenous vein graft (SVG) bypass. The patient presented with chest pain and a non‐ST‐elevation myocardial infarction. He underwent cardiac catheterization that showed a complete fracture of a zotarolimus‐eluting stent in the ostium of a sequential SVG to the diagonal and obtuse coronary arteries. His management included coronary angioplasty and retrieval of the proximal fractured segment. We discuss the potential causes for this stent fracture and suggest caution when using a DES in an ostial location of a SVG bypass, especially in a highly mobile vessel. © 2012 Wiley Periodicals, Inc.     

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.     

Clinical outcome of stent implantation in small coronary arteries using different types of coronary stents

PURPOSE: We evaluated the results of stent placement in small coronary arteries. SUBJECTS: The subjects were divided into 2 groups: the first contained 911 lesions treated with stenting in the coronary arteries (stent group), and the second contained 1,203 background- and patient-matched lesions treated with balloon angioplasty (POBA group). There was no significant difference in the background of patients or lesions between the groups. A "small coronary artery" was defined as a coronary artery with a reference vessel diameter < 3.0 mm. RESULTS: There was no significant difference in incidence of acute myocardial infarction (AMI), coronary artery bypass grafting, or death between the groups. In the stent group, acute occlusion (0.8%) and subacute thrombosis (2.1%) occurred. The restenosis rate of 29.8% in the stent group was significantly lower than in the POBA group (38.2%; p < 0.01). The restenosis rate of 19.4% in stented vessels 3.0 mm diameter was significantly lower than in vessels < 3.0 mm diameter (29.8%; p < 0.01). The rate of restenosis was 22.9% for the Multi-Link stent, 24.4% for the NIR stent, 34.1% for the GFX stent, and 35.3% for the PS stent. The restenosis rate of 23.8% in stented vessels > 2.5 mm diameter and < or = 20 mm length was significantly lower than in vessels , < or = 2.5 mm diameter and > 20 mm length (32.7%; p < 0.01). Factors associated with restenosis, analyzed using a stepwise multivariate logistic regression model, included ostial lesions and post-procedural minimum lumen diameter. CONCLUSIONS: Stent implantation in vessels < 3.0 mm diameter using a newly designed coronary stent yielded favorable clinical results, while there was a high prevalence of restenosis, leading to diffused stenotic lesions, in vessels < 2.5 mm diameter.     

Controlled Release of Heparin Reduces Neointimal Hyperplasia in Stented Rabbit Arteries: Ramifications for Local Therapy

Percutaneous coronary angioplasty is limited by neointimal hyperplasia and restenosis. Endovascular stenting has been proposed as a possible means of limiting this process. In practice stents have achieved early patency but are beset by early thrombosis and late restenosis. Heparin administered locally or systemically reduces smooth muscle cell hyperplasia following arterial injury in animals. Balloon-expandable stainless steel stents were placed in de-endothelialized rabbit iliac arteries to determine whether heparin released locally from perivascular matrices could reduce stent induced thrombosis and intimal hyperplasia. All animals received oral aspirin beginning 1 day prior to implantation and an IV bolus of heparin at balloon injury and stent placement. Heparin releasing ethylene-vinyl acetate copolymer matrices were placed adjacent to the stented portion of the artery in the treated group of rabbits. Thrombosis was evident in 30% of ten control arteries 14 days after stent placement and was reduced to 0% in nine segments receiving local heparin therapy (P < 0.05). Intimal hyperplasia was present in all experimental arterial sections, but total intimal area normalized for induced injury was reduced at 14 days from 12.6 ± 0.9 mm² in controls, to 6.8 ± 1.0 mm² in treated arteries (P < 0.001). Our results with perivascular drug administration may shed some light on the pathobiology of the vascular response to endovascular stent insertion and might assist in the design of novel means for enhancing the utilization of angioplasty and other interventional procedures.     

The use of intra-coronary optical coherence tomography for the assessment of sirolimus-eluting stent fracture

Drug-eluting stents (DES) have made a tremendous impact on the practice of percutaneous coronary intervention. Recently however, long-term DES failures have become a focal point, particularly with restenosis and thrombosis. An uncommon, yet important cause of DES failure is stent fracture. Of the two established first generation DES, the sirolimus-eluting stent (SES) has been particularly linked to cases of stent fracture, likely as a result of its closed cell design compared with other DES employing an open cell system. We present 2 cases of SES fracture confirmed using high-resolution intravascular optical coherence tomography giving unique insights into the in-vivo appearance of this complication.