Stent fracture and restenosis in the drug-eluting stent era

Drug-Eluting Stent Restenosis: Modern Approach to a Classic Challenge

In-stent restenosis (ISR) is a recognized complication following percutaneous coronary intervention in which the luminal diameter is narrowed through neointimal hyperplasia and vessel remodeling. Although rates of ISR have decreased in most recent years owing to newer generation drug-eluting stents, thinner struts, and better intravascular imaging modalities, ISR remains a prevalent dilemma that proves to be challenging to manage. Several factors have been proposed to contribute to ISR formation, including mechanical stent characteristics, technical factors during the coronary intervention, and biological aspects of drug-eluting stents. Presentation of ISR can range from asymptomatic to late myocardial infarction and could be difficult to differentiate from acute thrombus formation. No definite guidelines are present on the management of ISR. In this review, we will discuss the mechanisms underlying ISR and provide insight into patient-related and procedural risk factors contributing to ISR, in addition to highlighting common treatment approaches utilized in the management of ISR.

Incidence of coronary drug-eluting stent fracture: A systematic review and meta-analysis

Background

Reported evidence of coronary stent fracture (CSF) has increased in recent years. The purpose of this study was to determine reliable estimates of the overall incidence of CSF.

Methods and results

The MEDLINE, Embase and Cochrane databases were searched until March 18, 2022. Pooled estimates were acquired using random effects models. Meta-regression and subgroup analysis were used to explore sources of heterogeneity, and publication bias was evaluated by visual assessment of funnel plots and Egger’s test. Overall, 46 articles were included in this study. Estimates of CSF incidence were 5.5% [95% confidence interval (CI): 3.7–7.7%] among 39,953 patients based on 36 studies, 4.8% (95% CI: 3.1–6.8%) among 39,945 lesions based on 29 studies and 4.9% (95% CI: 2.5–9.4%) among 19,252 stents based on 8 studies. There has been an obvious increase in the incidence of CSF over the past two decades, and it seems that the duration of stent placement after stent implantation has no impact on incidence estimation.

Conclusion

The incidence of CSF was 5.5% among patients, 4.8% for lesions and 4.9% for stents and increased over the past 20 years. The duration of stent placement after stent implantation was found to have no impact on the incidence of CSF, but drug-eluting stent (DES) types and right coronary artery (RCA) lesions influenced the pooled incidence.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022311995], identifier [CRD42022311995].

Management of in-stent restenosis

In-stent restenosis (ISR) remains the most common cause of stent failure after percutaneous coronary intervention (PCI). Recent data suggest that ISR-PCI accounts for 5-10% of all PCI procedures performed in current clinical practice. This State-of-the-Art review will primarily focus on the management of ISR but will begin by briefly discussing diagnosis and classification. We then move on to detail the evidence base underpinning the various therapeutic strategies for ISR before finishing with a proposed ISR management algorithm based on current scientific data.

Fracture of self-expandable metallic stent inserted for unresectable gastric cancer at the esophagogastric junction: successful retrieval of distal fragment by gastrotomy

Endoscopic stenting is useful for amelioration of gastrointestinal stenosis. This procedure benefits severely compromised patients who cannot afford surgery. Although the self-expandable metallic stent (SEMS) is safe, it is also associated with several complications such as perforation, migration, and fracture. Migration of a SEMS is not particularly rare; however, fracture of a SEMS is relatively rare. An 88-year-old man underwent stenting for dysphagia at another hospital. He was being treated for gastric cancer at the esophagogastric junction. After appropriate stenting, he regained his ability to eat and was discharged the hospital. Only 2 months later, however, he again lost his ability to eat and visited our hospital. Abdominal X-ray and computed tomography revealed a stent fracture. The proximal fragment was in the esophagus, and the distal fragment was in the stomach. An emergency operation involving gastrotomy and gastrostomy was performed. Open gastrotomy was performed to remove the fractured distal stent, and percutaneous tube gastrostomy was placed through the same gastric incision for nutrition support. The surgery was successful, and he was again able to eat. In this report, we discuss the occurrence of SEMS fracture within a short time periods after insertion.

Peri-Contrast Staining as a Marker of Stent Failure: Restenosis, Thrombosis, and Fracture

Peri-stent contrast staining (PSS), defined as contrast staining around the stent struts, has been identified as an indicator of future stent failure in first generation, sirolimus-eluting coronary stents. 1 PSS has been associated with in-stent restenosis, stent thrombosis, stent fracture, and the development of coronary aneurysm. As the frequency of patients with first generation sirolimus-eluting coronary stents becomes infrequent; PSS may go unrecognized. Herein, we present a patient with a decade of longitudinal follow-up, who developed PSS identified on coronary angiogram with recurrent stent failure.

Comparison of Drug-Coated Balloons to Bare Metal Stents in the Treatment of Symptomatic Vertebral Artery-Origin Stenosis: A Prospective Randomized Trial

OBJECTIVE

We sought to compare the angiographic and clinical outcomes of drug-coated balloon (DCB) with distal embolic protection devices (EPDs) versus bare metal stent (BMS) without EPD in the treatment of symptomatic vertebral artery origin stenosis (VAOS).

METHODS

Between January 2017 and December 2018, a prospective randomized trial was conducted involving 95 patients with symptomatic VAOS randomly assigned to treatment with DCB + EPD (n = 49) or BMS without EPD (n = 46). Target vessel restenosis (RS) >50% detected by computed tomography angiography was the primary endpoint. Technical success, clinical success, and signal intensity abnormalities on diffusion-weighted imaging within 3 days after operation were compared.

RESULTS

The 30-day technical success rate was 93.9% for DCB group versus 95.7% for the BMS group (P = 0.094). Diffusion-weighted imaging within 3 days postoperative showed asymptomatic embolization in 2 (4.1%) patients in the DCB group and 9 (19.6%) patients in the BMS group (P = 0.004). At a mean 16-month follow-up, the clinical success rate was 89.8% for the DCB group versus 91.3% (42/46) for the BMS group (P = 0.125). The RS was seen in 5/49 (10.2%) in the DCB group and 6/46 (13.0%) in the BMS group (P = 0.082). Target vessel revascularization was performed in 4 (8.7%) BMS group versus 3 (6.1%) in the DCB group (P = 0.091).

CONCLUSIONS

DCB with EPD in the treatment of symptomatic VAOS is technically feasible and safe and significantly reduced thromboembolic events on imaging when compared with BMS without EPD. There was no significant difference between the 2 groups in the rate of RS during 12 months after surgery.

Fracture in drug-eluting stents increases focal intimal hyperplasia in the atherosclerosed rabbit iliac artery

OBJECTIVES

Drug-eluting stent (DES) strut fracture (SF) is associated with higher incidence of In-stent restenosis (ISR)-return of blockage in a diseased artery post stenting-than seen with bare metal stents (BMS). We hypothesize that concomitance of drug and SF leads to greater neointimal response.

BACKGROUND

Controlled release of therapeutic agents, such as sirolimus and its analogs, or paclitaxel from has reduced tissue based DES failure modes compared to BMS. ISR is dramatically reduced and yet the implications of mechanical device failure is magnified.

METHODS

Bilateral Xience Everolimus-eluting stents (EES) were implanted in 20 New Zealand White rabbits on normal (n = 7) or high fat (HF)/high cholesterol (HC) (n = 13) diets. Implanted stents were intact or mechanically fractured. Everolimus concentration was as packaged or pre-eluted. After 21 days, stented vessels were explanted, resin embedded, MicroCT scanned, and analyzed histomorphometrically.

RESULTS

Fractured EES were associated with significant (P < 0.05) increases in arterial stenosis and neointimal formation and lower lumen-to-artery area ratios compared to intact EES. Hyperlipidemic animals receiving pre-eluted EES revealed no significant difference between intact and fracture groups.

CONCLUSIONS

SF increases intimal hyperplasia, post EES implant, and worse with more advanced disease. Pre-eluted groups, reflective of BMS, did not show significant differences, suggesting a synergistic effect of everolimus and mechanical injury, potentially explaining the lack of SF reports for BMS. Here, we report that ISR has a higher incidence with SF in EES, the clinical implication is that patients with SF after DES implantation merit careful follow-up.

An Interesting Case and Literature Review of a Coronary Stent Fracture in a Current Generation Platinum Chromium Everolimus-Eluting Stent

Coronary interventions are the mainstay of treatment for stenotic coronary vascular lesions. New stent designs are constantly being evaluated to improve stent performances and clinical outcomes. Coronary stent fracture is uncommon; however, it is associated with potential major consequences including acute coronary syndrome and the need for repeated target vessel revascularization due to in-stent restenosis or stent thrombosis. We report a case of a 66-year-old man with an extensive cardiac disease history, who presented with intractable angina and was found to have a fracture of a current generation, platinum chromium everolimus-eluting stent (Synergy, Boston Scientific Inc.).

Low Cycle Fatigue Study of AISI 316L Cardiovascular Stent for Two Different Designs

The main originality of this work consists in investigating low cycle fatigue of AISI 316L cardiovascular stents under hypertensive loading. For this purpose, two geometries of stents are expanded to various diameters and subjected to hypertensive blood pressure. Based on a combination between the fatigue parameter of Jiang-Sehitoglu and the relationship of Coffin-Manson, a numerical model for the prediction of the number of cycles to crack failure is developed. The stent is found to exhibit a fatigue life reduction with the increase of the expansion diameter due to ratchetting strain. In addition, the location of the failure is independent on the design. However, the U-shape strut permits a better distribution of pressure over the stent strut resulting in a longer fatigue life as compared to the Ω-shape.

Stent Fracture and Peri-Stent Contrast Staining After Everolimus-Eluting Stent Implantation - 5-Year Outcomes

BACKGROUND

Stent fracture (SF) and peri-stent contrast staining (PSS) after sirolimus-eluting stent implantation are reported to be risk factors of adverse events. However, the effect of these after everolimus-eluting stent (EES) implantation on long-term outcomes remains unclear.Methods and Results:The study sample comprised 636 patients (1,081 lesions) undergoing EES implantation in 2010 and follow-up angiography within 1 year. The 5-year cumulative rates of target lesion revascularization (TLR) and major adverse cardiac events (MACE: a combination of all-cause death, myocardial infarction, and TLR) were compared between patients with and without SF or PSS. SF was observed in 2.7%, and PSS in 3.0%. The cumulative rates of MACE and TLR were significantly higher in the SF group than in the non-SF group (51.7% vs. 27.5% and 48.3% vs. 13.4%, respectively), but showed no significant differences between the PSS and non-PSS groups. In a landmark analysis, the rate of TLR within 1 year was significantly higher in the SF group than in the non-SF group (44.8% vs. 7.2%), but beyond 1 year showed no significant difference (6.3% vs 6.7%).

CONCLUSIONS

The 5-year clinical outcomes suggested that SF after EES implantation is related to increased risk of MACE and TLR, especially within 1 year after the procedure, but PSS after EES implantation is unrelated.

Stent fracture is associated with a higher mortality in patients with type-2 diabetes treated by implantation of a second-generation drug-eluting stent

Type 2 diabetes correlates with clinical events after the implantation of a second-generation drug-eluting stent (DES). The rate and prognostic value of stent fracture (SF) in patients with diabetes who underwent DES implantation remain unknown. A total of 1160 patients with- and 2251 without- diabetes, who underwent surveillance angiography at 1 year after DES implantation between June 2004 and August 2014, were prospectively studied. The primary endpoints included the incidence of SF and a composite major adverse cardiac event [MACE, including myocardial infarction (MI), cardiac death, and target-vessel revascularization (TVR)] at 1-year follow-up and at the end of follow-up for overall patients, and target lesion failure [TLF, including cardiac death, target vessel myocardial infarction (TVMI) and target lesion revascularization (TLR)] at the end of study for SF patients. In general, diabetes was associated with a higher rate of MACE at 1-year (18.4 vs. 12.9%) and end of follow-up (24.0 vs. 18.6%, all p < 0.001), compared with those in patients who did not have diabetes. The 1-year SF rate was comparable among patients with diabetes (n = 153, 13.2%) and non-diabetic patients (n = 273, 12.1%, p > 0.05). Diabetic patients with SF had a 2.6-fold increase of SF-related cardiac death at the end of study and threefold increase of re-repeat TLR when compared with non-diabetic patients with SF (5.9 vs. 2.2%, p = 0.040; 6.5 vs. 2.2%, p = 0.032), respectively. Given the fact that diabetes is correlated with increased MACE rate, SF in diabetic patients translates into differences in mortality and re-repeat TLR compared with the non-diabetic group.

Outcomes of First- Versus Second-Generation Drug-Eluting Stent Implanted for Right Coronary Artery Ostial Narrowing

Clinical outcome is generally poor when stents are implanted at right coronary artery ostial lesion (RCAos). We compared the clinical outcome between the first-generation drug-eluting stent (first DES) and second-generation drug-eluting stent (second DES) used for RCAos. Consecutive 88 patients who underwent percutaneous coronary interventions of de novo RCAos using the first DES (33 patients) or second DES (55 patients) were analyzed. The incidence of major adverse cardiac events (MACE) defined as the composite of cardiac death, myocardial infarction attributed to right coronary artery, and target lesion revascularization within 2.5 years was compared. The incidence of MACE was significantly lower in second DES (11% vs 36%, p = 0.010) than that in the first DES. Multivariate analysis revealed use of second DES (odds ratio 0.24, 95% CI 0.11 to 0.93, p = 0.008) alone was significantly associated with MACE. In conclusion, second DES revealed better clinical outcome than the first DES when used in de novo RCAos.

Zotarolimus-eluting stent fracture at initial implantation diagnosed with StentBoost

Stent fracture is a rare complication of drug-eluting stent implantation with a reported rate of 0.84%–3.2% in various clinical studies with first-generation drug-eluting stents and 29% in autopsy studies. Sirolimus-eluting stents with their closed cell design were reported to be more prone to fracture compared to paclitaxel-eluting stents. Other risk factors for stent fracture are multiple stenting, longer stent length, chronic renal failure, right coronary artery intervention, and a higher maximal inflation pressure. The role of angiography in diagnosing stent fracture is limited, a fact also questioning the reliability of angiographic data. Image enhancement techniques like StentBoost are widely available in new-generation angiography systems and are used to assess stent expansion, overlap size, or to localize the postdilation balloon. Here, we report a case of zotarolimus-eluting stent fracture at initial implantation diagnosed with StentBoost.

[Very late drug-eluting stent thrombosis by stent fracture]

The superiority of drug-eluting stents in reducing the risk of in-stent restenosis compared to bare-metal stents is no longer challenged. Nevertheless, the drug-eluting stents may carry long-term risk of late and very late stent thrombosis. The promoting factors of this complication are usually divided into three chapters depending on the patient, the procedure and the stent. Indeed, the literature has reported several parameters related to the stent itself, such as its length, the malapposition, its diameter, but also more rarely the occurrence of stent fracture. We present the case of a patient admitted for myocardial infarction after a very late thrombosis of Cypher drug-eluting stent four years after its implantation and related to stent fracture.

Stent fracture and longitudinal compression detected on coronary CT angiography in the first- and new-generation drug-eluting stents

To evaluated prevalence and clinical implication of stent fracture and longitudinal compression in first- and new-generation drug-eluting stents (DES) using coronary computed tomography angiography (CCTA). The incidence of stent fracture and longitudinal compression were compared between first- and new-generation DES in 374 patients who underwent coronary stenting using DES and follow-up CCTA due to recurrent angina. 235 and 139 patients received 322 first- and 213 new-generation DES, respectively. The crude per-stent incidence of longitudinal compression (6.1 vs. 0.3 %, p < 0.001) was higher after new- than first-generation DES implantation using CCTA and the incidence of stent fracture (11.3 vs. 8.1 %, p = 0.23) was comparable. On follow-up coronary angiography for 347 stents, stent fracture (3.2 %) and longitudinal compression (0.9 %) were less detected than those on CCTA. Ostial stenting was a risk factor of longitudinal compression (p < 0.001). Stent fracture was associated with younger patients (p = 0.03), longer stent (p = 0.010), and excessively tortuous lesions (p = 0.001). The presence of stent fracture or longitudinal compression was not associated with poor clinical outcomes. The longitudinal compression more frequently occurred after new-generation DES implantation. The stent fracture was comparable between two DES. However, the occurrence of such mechanical deformities did not translate into a poor clinical outcome.

Structural Mechanics Predictions Relating to Clinical Coronary Stent Fracture in a 5 Year Period in FDA MAUDE Database

Endovascular stents are the mainstay of interventional cardiovascular medicine. Technological advances have reduced biological and clinical complications but not mechanical failure. Stent strut fracture is increasingly recognized as of paramount clinical importance. Though consensus reigns that fractures can result from material fatigue, how fracture is induced and the mechanisms underlying its clinical sequelae remain ill-defined. In this study, strut fractures were identified in the prospectively maintained Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience Database (MAUDE), covering years 2006-2011, and differentiated based on specific coronary artery implantation site and device configuration. These data, and knowledge of the extent of dynamic arterial deformations obtained from patient CT images and published data, were used to define boundary conditions for 3D finite element models incorporating multimodal, multi-cycle deformation. The structural response for a range of stent designs and configurations was predicted by computational models and included estimation of maximum principal, minimum principal and equivalent plastic strains. Fatigue assessment was performed with Goodman diagrams and safe/unsafe regions defined for different stent designs. Von Mises stress and maximum principal strain increased with multimodal, fully reversed deformation. Spatial maps of unsafe locations corresponded to the identified locations of fracture in different coronary arteries in the clinical database. These findings, for the first time, provide insight into a potential link between patient adverse events and computational modeling of stent deformation. Understanding of the mechanical forces imposed under different implantation conditions may assist in rational design and optimal placement of these devices.

Complete stent fracture 1 year after LIMA PCI due to LIMA and subclavian artery dissection

Stent platforms are prone to fracture while incidental data are demonstrating a potential unfavorable outcome. Predisposing factors usually involve long lesions and tortuous vessels requiring more than one stent. This issue is magnified when it involves a periprocedural iatrogenic left internal mammary artery (LIMA) and subclavian artery dissection. In such complex clinical scenarios, the risk of potential complications including stent fractures is thought to be higher, though there is no data to determine the prognosis or to outline the outcomes of any management option. We present a case of complete stent fracture 1 year after LIMA percutaneous coronary intervention due to LIMA and subclavian artery dissection highlighting the circumstantial evidence in the literature that guided our management decisions.

Drug delivery of anti-restenosis agent by 40 - 60°C heating to porcine aortic smooth muscle cells in vitro

We investigated the uptake of anti-restenosis agent in vascular smooth muscle cells with heating observing the fluorescence intensity of Oregon green labeled paclitaxel in vitro. The heating temperature to porcine aortic smooth muscle cells was varied from 40 to 60°C in 5 s in order to simulate laser-mediated short-duration heating balloon. The cells were contacted with the agent from 1 to 30 min in 37°C after the heating. We measured the agent uptake characteristics on agent concentration and duration in 37°C as a reference. The uptake of the agent in the cells increased with increasing of both the concentration around the cells and contact duration in the case of 37°C. When the cells were heated with 40°C in 5 s and then contacted with the agent in 30 minutes, the uptake of the agent in the cells significantly increased. The uptake of the agent with 50°C or 60°C in 5 s did not show any increasing. We prospected that 40°C heating to the smooth muscle cells would promote the agent uptake ability of the cells because of homeostasis of the cells.

Two cases of immediate stent fracture after zotarolimus-eluting stent implantation

Drug-eluting stent (DES) implantation is currently the standard treatment for various types of coronary artery disease. However, previous reports indicate that stent fractures, which usually occur after a period of time from the initial DES implantation, have increased during the DES era; stent fractures can contribute to unfavorable events such as in-stent restenosis and stent thrombosis. In our present report, we describe two cases of zotarolimus-eluting stent fracture: one that was detected six hours after implementation, and the other case that was detected immediately after deployment. Both anatomical and technical risk factors contributed to these unusual cases of immediate 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.

Post-operative simultaneous very late two-vessel drug eluting stent thrombosis with sparing of bare metal stent in a Jehovah's witness after clopidogrel withdrawal

Very late stent thrombosis is a feared complication after drug-eluting stent (DES) implantation. Several factors related to the patient, generation and type of the deployed stent, procedure, and premature antiplatelet withdrawal are known to contribute to this complication. Herein, we describe a case of a Jehovah's witness patient who developed simultaneous two-vessel 1st generation DES thrombosis 5.4 and 3.5 years after deployment [with sparing of the bare metal stent (BMS)] in the immediate post-operative period secondary to clopidogrel withdrawal. The case was complicated by ST-segment elevation myocardial infarction, cardiogenic shock, and a ventricular fibrillation cardiac arrest requiring urgent percutaneous coronary intervention. The acute thrombosis of DESs with sparing of the BMS exemplify how they are more prone to this complication due to delayed endothelialization of stent struts and neoinitimal coverage. <Learning objective: Extreme caution should be excercised when attempting to withdraw antiplatelets immediately before surgery in patients with drug eluting stents even if the recomended 12-month period of dual antiplatelet therapy has elapsed because of the risk of very late stent thrombosis.>.

A multicenter randomized comparison of paclitaxel-coated balloon catheter with conventional balloon angioplasty in patients with bare-metal stent restenosis and drug-eluting stent restenosis

BACKGROUND

The aim of this study was to investigate the efficacy and safety of paclitaxel-coated balloon (PCB) for the treatment of the bare-metal stent restenosis (BMS-ISR) and drug-eluting stent restenosis (DES-ISR).

METHODS

This study was a prospective, multicenter, randomized (2:1) trial conducted in 208 patients with 213 in-stent restenosis lesions (BMS-ISR: 123 lesions, DES-ISR: 90 lesions) at 13 centers in Japan. Patients were randomly assigned to a PCB group (137 patients with 142 lesions) or a conventional balloon angioplasty (BA) group (71 patients with 71 lesions). The primary end point was target vessel failure at 6-month follow-up.

RESULTS

Clinical and angiographic follow-up 6 months after intervention was performed in 207 patients (99.5%) with 208 lesions (97.7%). Target vessel failure was noted in 6.6% of the PCB group and 31.0% of the BA group (P < .001). Recurrent restenosis occurred in 4.3% of the PCB group and 31.9% of the BA group (P < .001). Late lumen loss was lower in the PCB group than in the BA group (0.11 ± 0.33 mm vs 0.49 ± 0.50 mm, P < .001). In PCB-treated lesions, recurrent restenosis occurred in 1.1% of patients with BMS-ISR and in 9.1% of patients with DES-ISR (P = .04). Late lumen loss was lower in patients with BMS-ISR than in patients with DES-ISR (0.05 ± 0.28 mm vs 0.18 ± 0.38 mm, P = .03).

CONCLUSIONS

This randomized clinical study suggested that PCB provided much better clinical and angiographic outcomes than did conventional BA in patients with BMS-ISR and DES-ISR. Drug-eluting stent restenosis was associated with poorer outcomes compared with BMS-ISR after treatment with PCB.

Stent fracture: how frequently is it recognized?

In spite of there being several case reports, coronary stent fracture is not a well-recognized entity and incidence rates are likely to be underestimated. In this article, we review different aspects of stent fracture, including incidence, classification, predictors, outcome, diagnosis, and management.

Serial gray scale intravascular ultrasound findings in late drug-eluting stent restenosis

The primary aim of the present study was to assess the gray scale intravascular ultrasound (IVUS) findings that might be associated with late drug-eluting stent restenosis. The study included 47 patients (54 lesions) who had undergone either baseline IVUS-guided stent implantation or IVUS-guided repeat stenting to treat in-stent restenosis and then had IVUS follow-up data for ≥1.5 years afterward without any intervening procedures. The left anterior descending artery was the culprit in 59% of cases, and 50% of the lesions were at bifurcation sites. Quantitative and qualitative IVUS analyses showed a decreased minimum lumen area at follow-up from 6.0 ± 1.8 to 3.8 ± 1.4 mm(2) (p <0.0001) that was mainly due to neointimal hyperplasia with chronic stent recoil (defined as a >15% decrease in minimum stent area) in only 2 lesions and stent fracture in only 5 lesions. Calcified neointima appeared in 12 lesions, mostly in the form of macrocalcification, and was associated with increased calcium both behind the stent and in the reference segment. In conclusion, late drug-eluting stent restenosis showed neointimal calcification in 20% of cases, and chronic stent recoil was rare.

Research and development of metals for medical devices based on clinical needs

The current research and development of metallic materials used for medicine and dentistry is reviewed. First, the general properties required of metals used in medical devices are summarized, followed by the needs for the development of α + β type Ti alloys with large elongation and β type Ti alloys with a low Young's modulus. In addition, nickel-free Ni-Ti alloys and austenitic stainless steels are described. As new topics, we review metals that are bioabsorbable and compatible with magnetic resonance imaging. Surface treatment and modification techniques to improve biofunctions and biocompatibility are categorized, and the related problems are presented at the end of this review. The metal surface may be biofunctionalized by various techniques, such as dry and wet processes. These techniques make it possible to apply metals to scaffolds in tissue engineering.

Flat panel digital detector cinefluoroscopy late following SES or BMS implantation for detection of coronary stent fracture in asymptomatic patients

BACKGROUND

Coronary stent fracture (SF), is rare and confined mainly in patients treated with sirolimus eluting stents (SES). The role of flat panel digital detector (FPDD) fluoroscopy in detecting SF has not been investigated.

METHODS

Assessment with FPDD fluoroscopy of asymptomatic patients, with 200 SES (Cypher, Cordis, J&J, Miami, Florida, US), and 200 bare metal stents (BMS), at 45.5 ± 15.7 and 38.4 ± 3.9 months post-stenting respectively. SF was defined as discontinuity of stent struts on fluoroscopy. Coronary angiography was reserved for patients with documented SF.

RESULTS

Effective radiation dose was 0.26 ± 0.14 mSv. SF was depicted in 6 (3%) SES, and 1 BMS (0.5%). Stent length was an independent predictor of SF (OR 1.19, 95% CI 1.03-1.4, p=0.024). RCA location and vessel angulation were marginally significant (OR 7.7, 95% CI 0.8-74.2, p=0.077 and OR 5.1, 95% CI 0.8-34, p=0.089). Significant angiographic restenosis was detected in 4 SES (66.6%), and 1 BMS (0.5%). Re-intervention was needed in 3 (42.8%) cases, (2 SES and 1 BMS).

CONCLUSION

Detection of SF with FPDD cinefluoroscopy late following coronary stenting is feasible, involves low radiation and is confined mainly to SES compared to BMS. Application of cinefluoroscopy as part of a routine stent surveillance programme in asymptomatic patients may be more appropriate in "high risk" settings (SES, long stents and adverse angiographic characteristics). The role of invasive imaging and subsequent management of such patients need further studying.

Successful management of a rare case of stent fracture and subsequent migration of the fractured stent segment into the ascending aorta in in-stent restenotic lesions of a saphenous vein graft

Stent fracture is a complication following implantation of drug eluting stents and is recognized as one of the risk factors for in-stent restenosis. We present the first case of successfully managing a stent fracture and subsequent migration of the fractured stent into the ascending aorta that occurred during repeat revascularization for in-stent restenosis of an ostium of saphenous vein graft after implantation of a zotarolimus-eluting stent. Although the fractured stent segment had migrated into the ascending aorta with a pulled balloon catheter, it was successfully repositioned in the saphenous vein graft using an inflated balloon catheter. Then, the fractured stent segment was successfully connected to the residual segment of the zotarolimus-eluting stent by covering it with an additional sirolimuseluting stent.

[Sirolimus-eluting stent displaced fracture: case report and review of the literature]

Drug-eluting stents have greatly reduced the risk of in-stent restenosis compared to bare metal stents by inhibiting neointimal growth. However, they may carry some long-term risks, especially the risk of late stent thrombosis. Recently, several cases of drug-eluting stent fracture have been also reported. The mechanisms, the diagnosis, the clinical implications and the management of this new complication are not well-known. We report the observation of a new case of displaced, sirolimus drug-eluting stent fracture. To our knowledge, this is the first reported case in France.

Very delayed coronary stent fracture: A case report

A stent fracture is an emerging complication of the coronary stents. There are numerous risk factors for stent fractures; which include forceful exaggerated motion in the atrioventricular groove seen in right coronary artery, long stent, an ostial lesion at the point of maximum curvature in a tortuous vessel, stent over-expansion, stent overlapping with different size stents, complex lesion after stenting of a totally occluded vessel, Cypher stent and a highly mobile segment causing high mechanical stress. Furthermore, chronic stretch at specific vessel sites as bends may lead to late occurrence of fracture. Here we report a case of 40-year-old male who had two overlapping Cypher stents (3.0 × 13 mm and 2.75 × 18 mm) deployed at mid left anterior descending artery 2 years earlier presented with progressive chest pain.

Impact of Sirolimus-Eluting Stent Fracture on 4-Year Clinical Outcomes

Background—

Although stent fracture (SF) after sirolimus-eluting stent (SES) implantation has been recognized as one of the predisposing factors of in-stent restenosis, it remains uncertain whether SF can increase the risk of major adverse cardiac events (MACE), especially beyond 1 year after SES implantation. The aim of this study was to assess the impact of SF relative to non-SF on 4-year clinical outcomes after treatment with SES of comparable unselected lesions.

Methods and Results—

A total of 874 lesions in 793 patients undergoing SES implantation and subsequent angiography 6 to 9 months after index procedure were analyzed. At 6- to 9-month angiographic follow-up, SF was identified in 70 of 874 lesions (8.0%). In-stent late loss was significantly higher in SF lesions versus non-SF lesions (0.42±0.59 mm versus 0.13±0.49 mm, P <0.001), resulting in a significantly higher in-stent restenosis rate (21.4% versus 4.1%, P <0.001). At 4 years, SF versus non-SF was associated with a significantly higher MACE rate (23.2% versus 12.6%, P =0.014), mainly driven by significantly higher target-lesion revascularization (18.8% versus 10.2%, P =0.029) rate. Adverse effects of SF on clinical outcomes occurred mostly within the first year (17.4% versus 6.6%, P =0.001), with similar MACE rate between 1 and 4 years (5.8% versus 5.9%, P =0.611). No significant differences between SF versus non-SF patients were observed in the cumulative frequency of very late stent thrombosis (2.9% versus 1.4%, P =0.281), death (0% versus 2.1%, P =0.252), or myocardial infarction (5.8% versus 2.9%, P =0.165).

Conclusions—

SF of SES was associated with higher MACE rate up to 1 year, mainly driven by higher target-lesion revascularization, whereas no significant association was evident between years 1 and 4.

Effectiveness of paclitaxel-eluting balloon catheter in patients with sirolimus-eluting stent restenosis

OBJECTIVES

The aim of this study was to investigate the efficacy of a paclitaxel-eluting balloon (PEB) for the treatment of sirolimus-eluting stent (SES) restenosis.

BACKGROUND

Because drug-eluting stents (DES) are being used in increasingly complicated settings, DES restenosis is no longer an uncommon phenomenon, and its optimal treatment is unknown.

METHODS

This study was a prospective single-blind randomized trial conducted in 50 patients with SES restenosis. Patients were randomly assigned to a PEB group (n = 25) or a conventional balloon angioplasty (BA) group (n = 25). The primary end point was late lumen loss at 6-month follow-up. Secondary end points included the rate of binary restenosis (in-segment analysis) and major adverse cardiac events (MACE) at 6-month follow-up.

RESULTS

At 6-month angiographic follow-up (follow-up rate: 94%), in-segment late lumen loss was lower in the PEB group than in the BA group (0.18 ± 0.45 mm vs. 0.72 ± 0.55 mm; p = 0.001). The incidence of recurrent restenosis (8.7% vs. 62.5%; p = 0.0001) and target lesion revascularization (4.3% vs. 41.7%; p = 0.003) was also lower in the PEB group than in the BA group. The cumulative MACE-free survival was significantly better in the PEB group than in the BA group (96% vs. 60%; p = 0.005).

CONCLUSIONS

In patients with SES restenosis, PEB provided much better clinical, angiographic outcomes than conventional BA.