The contribution of "mechanical" problems to in-stent restenosis: An intravascular ultrasonographic analysis of 1090 consecutive in-stent restenosis lesions

Incidence, predictors, and clinical impact of the impeded-by-stent phenomenon after placing two-linked design new generation drug-eluting stents

BACKGROUND

When a catheter device is delivered during percutaneous coronary intervention, its passage can be disrupted by a deployed in a coronary artery. However, the condition and details of this phenomenon, that is impeded-by-stent phenomenon (ISP), remain unclear.

METHODS

We designed a prospective, open-label, single-center, observational study to clarify the incidence, predictors, and clinical impact of ISP in drug-eluting stents (DESs). Two independent operators observed and judged the occurrence of ISP, which was defined as all disturbances to a device delivery by deployed DESs. We consecutively used the Ultimaster™ (Terumo, Tokyo, Japan) DES for one month (109 patients, October 2018), followed by the Synergy™ (Boston Scientific Corporation, Marlborough, MA, USA) DES the next month (119 patients, November 2018).

RESULTS

DESs (2.5-4.0 mm in diameter) were implanted in 230 de novo coronary vessels. ISPs were observed in 17 of 239 stented segments (7.1 %). Multivariate analysis showed that bifurcation lesions (adjusted odds ratio [OR], 4.2; 95 % confidence interval [CI], 1.5-12.6; p = 0.008), predilatation balloon diameter (mm) (OR, 0.2; 95 % CI, 0.1-0.9; p = 0.03), and Ultimaster™ use (OR, 6.0; 95 % CI, 1.9-27.2; p = 0.002) were independent predictors of ISPs. During the 1.5-year follow-up period, no repeat revascularization or stent thrombosis occurred in patients with ISP.

CONCLUSIONS

ISP itself does not trigger notable clinical outcomes, including repeat revascularization and stent thrombosis. However, caution should be considered regarding the latent risk of procedural complications.

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.

Endovascular Debulking of Human Carotid Plaques by Using an Excimer Laser Combined With Balloon Angioplasty: An ex vivo Study

Purpose: We aimed to evaluate the safety and effectiveness of applying an excimer laser in debulking human carotid atherosclerotic plaques by investigating the distal debris, plaque luminal gain, and micromorphology of the plaque surface.

Methods: Eighteen plaque samples obtained from carotid endarterectomy (CEA) were randomly allocated to the excimer laser ablation (45 mJ/mm², 25 Hz) alone group (group 1), balloon angioplasty (8 atm) alone group (group 2), and excimer laser ablation combined with balloon angioplasty group (group 3). Hematoxylin–eosin staining and Movat's pentachrome staining were performed on the collected particles to quantify the size and composition of the debris. The superficial micromorphological structure of the plaque lumen surface after device treatments was observed using a scanning electron microscope. Micro-CT, tissue sections, and pathological stainings were applied to the treated plaques. The plaque lumen and artery lumen were three-dimensionally reconstructed using clinical computed tomography angiography and the micro-CT images. Lumen enlargement was set as the main measurement of effectiveness.

Results: Group 3 produced the highest luminal gain (5.40 ± 4.51 mm²), while the other two groups had gains of 4.05 ± 3.20 and 3.77 ± 2.55 mm². Both devices caused disruptions to the plaque lumen surface. Laser ablation exposed the fibers under the endothelium and balloon angioplasty cracked the surface. The mean amounts were 3,611 ± 1,475.4 for group 1, 2,828 ± 1,266.7 for group 2, and 4,400 ± 2,567.9 for group 3. More than 90% of the distal debris was smaller than 10 μm. Group 2 produced the most debris with Feret (maximum caliper diameter) ≥ 40 μm; group 1 had the least. There was little difference in the contents of collagen and reticular fiber in the debris in each group, but a big difference was observed in the contents of fibrin and mucin.

Conclusion: Excimer laser ablation could significantly increase the luminal gain of carotid plaque with high stenosis. Excimer laser combined with balloon angioplasty achieved the highest lumen enlargement. Our result also suggests that the embolic protection strategy needs to be renewed for the application of a plaque debulking device in the future.

Flash Ostial Balloon in Right Internal Mammary Artery Percutaneous Coronary Intervention: A Novel Approach

Despite the widespread use of coronary stents and effective anticoagulation regimens, the treatment of ostial lesions is limited by high restenosis rates. Ostial stenosis is a technically difficult condition to treat but this novel technique shows the ability to enable the optimal coverage of the ostium with excellent stent flaring using a Flash ostial balloon (Cardinal Health Inc., Dublin, OH).

Reconstruction of an accidentally crushed stent guided by intravascular ultrasound during a left main percutaneous coronary intervention

We present a case of an accidentally crushed stent due to an unnoticed passage of a guidewire through a lateral stent strut with subsequent stent compression after balloon dilatation, during a planned percutaneous coronary intervention on the left main. The crushed stent segment was reconstructed with step-by-step balloon dilation, guided by intravascular ultrasound.

Diagnostic value of microRNA-143 in predicting in-stent restenosis for patients with lower extremity arterial occlusive disease

Purpose

This study was conducted to explore the diagnostic value of microRNA-143 (miRNA-143) in predicting in-stent restenosis (ISR) of lower extremity arterial occlusive disease (LEAOD).

Methods

From February 2012 to March 2015, 165 patients (112 males and 53 females) with LEAOD undergoing interventional treatment were enrolled in this study. Serum miRNA-143 expression was detected using quantitative real-time polymerase chain reaction (qRT-PCR). Patients were assigned into the restenosis and non-restenosis groups according to routine surveillance postoperative angiography. A logistic regression analysis was conducted to analyze the risk factors for ISR in LEAOD patients. A receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic value of miRNA-143 in predicting ISR for LEAOD patients.

Results

There were 74 and 91 patients in the restenosis and non-restenosis groups, respectively. Before the treatment, there were significant differences in history of diabetes, smoking status, blood sugar level (BSL) at admission, low-density lipoprotein cholesterol (LDL-C) level, and stent diameter between the restenosis and non-restenosis groups (all P < 0.05). Serum miRNA-143 expression was lower in the restenosis group than in the non-restenosis group (P < 0.05). Serum miRNA-143 expression in the restenosis group was correlated with smoking status, history of diabetes, BSL, and LDL-C (all P < 0.05). Logistic regression analysis demonstrated that miRNA-143, LDL-C, and smoking status were correlated with the postoperative ISR (all P < 0.05). ROC curve analysis revealed that the area under the curve (AUC) of miRNA-143 in predicting ISR for LEAOD patients was 0.866.

Conclusion

Our results indicate that miRNA-143 can be a promising tool for predicting the ISR in LEAOD patients.

Mechanisms and Patterns of Intravascular Ultrasound In-Stent Restenosis Among Bare Metal Stents and First- and Second-Generation Drug-Eluting Stents

The most common causes of in-stent restenosis (ISR) are intimal hyperplasia and stent under expansion. The purpose of this study was to use intravascular ultrasound (IVUS) to compare the ISR mechanisms of bare metal stents (BMS), first-generation drug-eluting stents (DES), and second-generation DES. There were 298 ISR lesions including 52 BMS, 73 sirolimus-eluting stents, 52 paclitaxel-eluting stents, 16 zotarolimus-eluting stents, and 105 everolimus-eluting stent. Mean patient age was 66.6 ± 1.1 years, 74.2% were men, and 48.3% had diabetes mellitus. BMS restenosis presented later (70.0 ± 66.7 months) with more intimal hyperplasia compared with DES (BMS 58.6 ± 15.5%, first-generation DES 52.6 ± 20.9%, second-generation DES 48.2 ± 22.2%, p = 0.02). Although reference lumen areas were similar in BMS and first- and second-generation DES, restenotic DES were longer (BMS 21.8 ± 13.5 mm, first-generation DES 29.4 ± 16.1 mm, second-generation DES 32.1 ± 18.7 mm, p = 0.003), and stent areas were smaller (BMS 7.2 ± 2.4 mm(2), first-generation DES 6.1 ± 2.1 mm(2), second-generation DES 5.7 ± 2.0 mm(2), p <0.001). Stent fracture was seen only in DES (first-generation DES 7 [5.0%], second-generation DES 8 [7.4%], p = 0.13). In conclusion, restenotic first- and second-generation DES were characterized by less neointimal hyperplasia, smaller stent areas, longer stent lengths, and more stent fractures than restenotic BMS.

Mechanical complications of everolimus-eluting stents associated with adverse events: an intravascular ultrasound study

AIMS

Mechanical complications contribute to bare metal and first-generation drug-eluting stent (DES) failure. However, the importance of the mechanical complications of second-generation DES remains unclear. We report mechanical complications associated with everolimus-eluting stent (EES) failures.

METHODS AND RESULTS

We retrospectively analysed 177 consecutive EES-treated lesions in 136 patients who underwent intravascular ultrasound (IVUS) at follow-up. Mechanical complications were identified in 17 patients (five stable angina, 10 unstable angina, two non-ST-elevation myocardial infarction [NSTEMI] without angiographic thrombus). Fifteen (88.2%) were treated with repeat revascularisation. By IVUS, there were 16 focal (94.1%) and one diffuse (5.9%) in-stent restenoses. Complete stent fracture with separation was seen in only one, partial stent fracture with separation was seen in three, and in 13 there was longitudinal deformation (n=2) or stent strut fracture (n=11) with overlapping of the proximal and distal stent fragments. In 13 EES with evidence of overlapping in the setting of either fracture or deformation, there was a 35.5±12.2% smaller stent area compared to the adjacent proximal and distal stent fragments, and >50% neointimal hyperplasia in 12 (92.3%).

CONCLUSIONS

We found EES mechanical complications, often followed by longitudinal deformation or fracture leading to excessive neointimal hyperplasia, in-stent restenosis, and repeat revascularisation.

A novel technique for catheter engagement of protruding aorto-ostial stent

We present a case of stenoses in the right coronary artery with a previously deployed stent showing gross protrusion into the aorta. Despite difficulty in cannulation of a guiding catheter into the coronary artery, percutaneous intervention was accomplished using a novel technique to engage the protruding stent.

Clinical utility of intravascular imaging and physiology in coronary artery disease

Intravascular imaging and physiology techniques and technologies are moving beyond the framework of research to inform clinical decision making. Currently available technologies and techniques include fractional flow reserve; grayscale intravascular ultrasound (IVUS); IVUS radiofrequency tissue characterization; optical coherence tomography, the light analogue of IVUS; and near-infrared spectroscopy that detects lipid within the vessel wall and that has recently been combined with grayscale IVUS in a single catheter as the first combined imaging device. These tools can be used to answer questions that occur during daily practice, including: Is this stenosis significant? Where is the culprit lesion? Is this a vulnerable plaque? What is the likelihood of distal embolization or periprocedural myocardial infarction during stent implantation? How do I optimize acute stent results? Why did thrombosis or restenosis occur in this stent? One of the legacies of coronary angiography is to presume that one technique will answer all of these questions; however, that often has been proved inaccurate in contemporary practice.

Impact of Intravascular Ultrasound in Clinical Practice

Intravascular ultrasound (IVUS) has expanded our understanding of atherosclerotic plaque morphology, and provides an opportunity to guide cardiovascular interventions and evaluate results. Use of this technique requires understanding of ultrasound physics, catheter differences, skills in vessel, plaque and stent quantification and knowledge of artifacts and various physiologic and pathologic findings. Optimal cardiovascular interventions should result in absence of inflow or outflow obstruction, precise geographic landing, while attaining the largest feasible luminal gain without plaque protrusion, vessel dissection or perforation and, if deployed, with complete stent expansion and apposition to the vessel wall. IVUS is safe, cost efficient and effectively optimises cardiovascular interventions. In addition, IVUS improves outcomes when used to guide coronary interventions using bare metal stents (BMS) and drug eluting stents (DES). The role of IVUS in endovascular therapy is rapidly expanding. This review will focus on the impact of IVUS in clinical practice.

Oxidative stress and pathological changes after coronary artery interventions

Oxidative stress greatly influences the pathogenesis of various cardiovascular disorders. Coronary interventions, including balloon angioplasty and coronary stent implantation, are associated with increased vascular levels of reactive oxygen species in conjunction with altered endothelial cell and smooth muscle cell function. These alterations potentially lead to restenosis, thrombosis, or endothelial dysfunction in the treated artery. Therefore, the understanding of the pathophysiological role of reactive oxygen species (ROS) generated during or after coronary interventions, or both, is essential to improve the success rate of these procedures. Superoxide O2(·-) anions, whether derived from uncoupled endothelial nitric oxide synthase, nicotinamide adenine dinucleotide phosphate oxidase, xanthine oxidase, or mitochondria, are among the most harmful ROS. O2(·-) can scavenge nitric oxide, modify proteins and nucleotides, and induce proinflammatory signaling, which may lead to greater ROS production. Current innovations in stent technologies, including biodegradable stents, nitric oxide donor-coated stents, and a new generation of drug-eluting stents, therefore address persistent oxidative stress and reduced nitric oxide bioavailability after percutaneous coronary interventions. This review discusses the molecular mechanisms of ROS generation after coronary interventions, the related pathological events-including restenosis, endothelial dysfunction, and stent thrombosis-and possible therapeutic ways forward.

Compound ex vivo and in silico method for hemodynamic analysis of stented arteries

Hemodynamic factors such as low wall shear stress have been shown to influence endothelial healing and atherogenesis in stent-free vessels. However, in stented vessels, a reliable quantitative analysis of such relations has not been possible due to the lack of a suitable method for the accurate acquisition of blood flow. The objective of this work was to develop a method for the precise reconstruction of hemodynamics and quantification of wall shear stress in stented vessels. We have developed such a method that can be applied to vessels stented in or ex vivo and processed ex vivo. Here we stented the coronary arteries of ex vivo porcine hearts, performed vascular corrosion casting, acquired the vessel geometry using micro-computed tomography and reconstructed blood flow and shear stress using computational fluid dynamics. The method yields accurate local flow information through anatomic fidelity, capturing in detail the stent geometry, arterial tissue prolapse, radial and axial arterial deformation as well as strut malapposition. This novel compound method may serve as a unique tool for spatially resolved analysis of the relationship between hemodynamic factors and vascular biology. It can further be employed to optimize stent design and stenting strategies.

Clinical Outcomes and Treatment After Drug-Eluting Stent Failure

Background—

The optimal percutaneous treatment of drug-eluting stent (DES) in-stent restenosis (ISR) and the correlates for recurrent DES ISR remain unclear.

Methods and Results—

From 2003 to 2008, 563 patients presenting with recurrent symptoms of ischemia and angiographic ISR after DES implantation were included. Of these, 327 were treated with re-DES (58.1%), 132 underwent vascular brachytherapy (23.4%), and 104 were treated with conventional balloon angioplasty (18.5%). Variables associated with target lesion revascularization at 1 year were explored by individual proportional hazard models. This population presents a high prevalence of comorbidities, including diabetes (43.7%), previous myocardial infarction (MI) (45.8%), coronary bypass graft surgery (39.2%), chronic renal failure (18.8%), and heart failure (17.3%). Baseline clinical characteristics were balanced among the 3 groups; however, patients undergoing vascular brachytherapy presented with more complex lesions and a higher prevalence of prior stent/vascular brachytherapy failure than did the rest of the population. The overall incidence of recurrent DES failure at 1-year follow-up was 12.2%, which was similar among the 3 groups ( P =0.41). The rate of the composite end point (death, Q-wave-MI and target lesion revascularization) at 1-year follow-up was 14.1% for re-DES, 17.5% for vascular brachytherapy, and 18.0% for conventional balloon angioplasty ( P =0.57). After univariable analysis tested the traditional known covariates related to ISR, none of them were associated with repeat target lesion revascularization.

Conclusions—

Recurrence of ISR after DES treatment failure is neither infrequent nor benign, and optimal therapy remains unclear and challenging. Given the absence of traditional risk factors for ISR in this population, further research is required to elucidate both the correlates involved in DES ISR and the optimal treatment for this condition.

Comparison of long-term clinical and angiographic outcomes following implantation of bare metal stents and drug-eluting stents in aorto-ostial lesions

Percutaneous coronary intervention (PCI) to aorto-ostial (AO) lesions is technically demanding and associated with high revascularization rates. The aim of this study was to assess outcomes after bare metal stent (BMS) compared to drug-eluting stent (DES) implantation after PCI to AO lesions. A retrospective cohort analysis was conducted of all consecutive patients who underwent PCI to AO lesions at 2 centers. Angiographic and clinical outcomes in 230 patients with DES from September 2000 to December 2009 were compared to a historical control group of 116 patients with BMS. Comparison of the baseline demographics showed more diabetics (32% vs 16%, p = 0.001), lower ejection fractions (52.3 ± 9.7% vs 55.0 ± 11.5%, p = 0.022), longer stents (17.55 ± 7.76 vs 14.37 ± 5.60 mm, p <0.001), and smaller final stent minimum luminal diameters (3.43 ± 0.53 vs 3.66 ± 0.63 mm, p = 0.001) in the DES versus BMS group. Angiographic follow-up (DES 68%, BMS 66%) showed lower restenosis rates with DES (20% vs 47%, p <0.001). At clinical follow-up, target lesion revascularization rates were lowest with DES (12% vs 27%, p = 0.001). Cox regression analysis with propensity score adjustment for baseline differences suggested that DES were associated with a reduction in target lesion revascularization (hazard ratios 0.28, 95% confidence interval 0.15 to 0.52, p <0.001) and major adverse cardiac events (hazard ratio 0.50, 95% confidence interval 0.32 to 0.79, p = 0.003). There was a nonsignificantly higher incidence of Academic Research Consortium definite and probable stent thrombosis with DES (n = 9 [4%] vs n = 1 [1%], p = 0.131). In conclusion, despite differences in baseline characteristics favoring the BMS group, PCI with DES in AO lesions was associated with improved outcomes, with lower restenosis, revascularization, and major adverse cardiac event rates.

Current and evolving stent evaluation by coronary computed tomographic angiography

OBJECTIVES

To demonstrate the variety of stent abnormalities that may be evaluated by coronary computed tomographic angiography (CTA).

BACKGROUND

The application of CTA to the evaluation of coronary stents has focused almost entirely on the detection of in-stent restenosis.

METHODS

All CTA performed for stent evaluation at a single institution were reviewed.

RESULTS

In addition to in-stent restenosis, stent fracture, and overlap failure, a multiplicity of stent-related problems not previously addressed by CTA was categorized and illustrated: late stent thrombosis, jailed branches, edge stenosis, bifurcation stents, inadequate stent expansion, stent aneurysms, peri-stent plaque, and stenting into bridged myocardium.

CONCLUSIONS

CTA may be used to evaluate the full range of stent-related problems. This work provides the framework for future studies validating these applications.

Impact of post-intervention minimal stent area on 9-month follow-up patency of paclitaxel-eluting stents: an integrated intravascular ultrasound analysis from the TAXUS IV, V, and VI and TAXUS ATLAS Workhorse, Long Lesion, and Direct Stent Trials

OBJECTIVES

We investigated the predictive value of the intravascular ultrasound (IVUS) measured post-intervention minimum stent area (MSA) on 9-month follow-up paclitaxel-eluting stent (PES) patency compared with bare-metal stents (BMS).

BACKGROUND

Stent underexpansion is a strong predictor for restenosis after sirolimus-eluting stent implantation, but the implication of underexpansion in PES is still unknown.

METHODS

From the combined TAXUS IV, V, and VI and TAXUS ATLAS Workhorse, Long Lesion, and Direct Stent trials, 1,580 patients (PES 1,098, BMS 482) in IVUS substudies were analyzed. The MSA that best predicted angiographic in-stent restenosis (ISR) (% diameter stenosis > or =50%) was determined.

RESULTS

The post-intervention IVUS MSA was similar in PES and BMS (6.6 +/- 2.5 mm(2) vs. 6.7 +/- 2.3 mm(2), p = 0.92). At 9-month follow-up, ISR was lower in the PES group versus the BMS group (10% vs. 31%, p < 0.0001). Using multivariable logistic regression analysis, post-intervention IVUS MSA was the independent predictor of subsequent ISR in both the PES and BMS groups (p = 0.0002 for PES and p = 0.0002 for BMS). The ability of the post-intervention IVUS MSA to predict ISR was further assessed using receiver operating characteristic analysis. The post-intervention IVUS MSA was found to be a faithful discriminator between patients with and without ISR in both PES (c = 0.6382) and BMS (c = 0.6373). Finally, the optimal thresholds of post-intervention IVUS MSA that best predicted stent patency at 9 months were 5.7 mm(2) for PES and 6.4 mm(2) for BMS.

CONCLUSIONS

Post-intervention MSA measured by IVUS can predict 9-month follow-up stent patency after both PES and BMS implantation. (Randomized Trial Evaluating Slow-Release Formulation TAXUS Paclitaxel-Eluting Coronary Stents to Treat De Novo Coronary Lesions; NCT00301522) (Direct Stenting of TAXUS Liberté-SR Stent for the Treatment of Patients With de Novo Coronary Artery Lesions; NCT00371423) (A Study of the TAXUS Liberté Stent for the Treatment of Long De Novo Coronary Artery Lesions; NCT00371475) (A Study of the TAXUS Liberté Stent for the Treatment of de Novo Coronary Artery Lesions in Small Vessels; NCT00371748).

Impact of different re-stenting strategies on expansion of a drug-eluting stent implanted to treat bare-metal stent restenosis

We used intravascular ultrasound (IVUS) to compare the expansion of drug-eluting stents (DES) implanted to treat bare-metal stent (BMS) restenosis after 3 common re-stenting strategies. A total of 80 consecutive BMS restenotic targets were re-stented either directly (n = 30, group 1) or after low-pressure (<8 atm) pre-dilation with an undersize regular balloon (n = 16, group 2) or after high-pressure (>12 atm) pre-dilation with a semicompliant balloon the same or greater diameter as the original BMS diameter (n = 34, group 3). More patients from groups 2 and 3 had diabetes mellitus. The targets in group 1 were more proximal and focal. Lesions from groups 2 and 3 were more severe. The size and deployment pressure of the DESs and the achieved angiographic results were all similar. The post-intervention minimum stent area and the percentage of expansion of DES (minimum stent area/distal reference lumen area x 100%) were, however, both significantly larger in group 3 (6.4 +/- 1.5 mm(2) in group 3 vs 5.6 +/- 1.6 mm(2) in group 1 vs 4.4 +/- 1.4 mm(2) in group 2, p <0.001; and 88 +/- 30% in group 3 vs 74 +/- 14% in group 1 vs 73 +/- 23% in group 2, p = 0.021). A post-intervention minimum stent area <5.0 mm(2) was seen in only 3 lesions in group 3 (8.8%) versus 14 in group 1 (46.7%) and 11 in group 2 (68.8%; adjusted odds ratio 0.11, 95% confidence interval 0.03 to 0.38, p <0.001). Overall, the acute lumen gain was mainly from BMS re-expansion; however, the BMS volume increased the most in group 3 (p <0.001). In conclusion, high-pressure pre-dilation leads to superior post-intervention expansion of DESs implanted to treat BMS restenosis, regardless of the original expansion because of the greater BMS re-expansion.

Wall shear stress in intracranial self-expanding stents studied using ultra-high-resolution 3D reconstructions

BACKGROUND AND PURPOSE

Imaging of intracranial stents is constrained by resolution limits of current clinical imaging techniques providing insufficient visualization of deployment details and impeding its use for computational hemodynamic (CHD) simulations. The purpose of our study was to evaluate whether ultra-high-resolution MicroCT scans can illuminate detailed aspects of realistic in vitro stent deployment and serve as a reliable basis for CHD simulations of blood flow through self-expanding intracranial stents.

MATERIALS AND METHODS

A Neuroform Treo (NF) stent and an Enterprise (ENT) stent were deployed in identical straight polytetrafluoroethylene tubes filled with contrast agent. MicroCT scans were obtained at a spatial resolution of 14 mum and used for ultra-high-resolution 3D reconstructions. CHD simulations were performed, with particular emphasis on local flow behavior near the wall and struts. Flow differences between the geometrically different stents were studied.

RESULTS

MicroCT data revealed strut prolapse near the markers for the closed-cell design (ENT) stent and at some of the unconnected vertices of the open-cell design (NF) stent, which also showed some misalignments. CHD simulations showed that reverse wall shear stress occurred near some of the strut vertices and markers for the NF but only near the markers for the ENT.

CONCLUSIONS

This work demonstrates the feasibility of ultra-high-resolution MicroCT imaging in elucidating important details of intracranial stent deployment as a basis for accurate CHD simulations and in enabling a structural and hemodynamic study of realistically deployed stents with different geometry and design.

Intravascular ultrasound (IVUS) guided fixation of an accidentally crushed coronary stent

Stent deployment during coronary intervention has become more and more common recently. Inappropriate stent deployment may lead to unexpected high mortality and morbidity rates. A 62 year-old man with unstable angina presented with a bifurcation lesion after diagnostic coronary angiography. A drug-eluting stent was successfully deployed across the bifurcation lesion. However, after wire exchange and rewiring followed by high pressure balloon postdilatation, the stent was accidentally crushed under IVUS guidance. We used a looping wire technique and successfully redilated the crushed instent portion. This case suggests interventionists should not always change the wire before stent well deployment and should bear in mind the value of IVUS in managing such a complication.

Acute lumen overdilation improves outcome after brachytherapy of in-stent restenosis

BACKGROUND

The aim of our study was to test the impact of acute lumen overdilation on neointimal hyperplasia and late lumen size after vascular brachytherapy for in-stent restenosis (ISR).

METHODS

Forty-seven ISR lesions located in 47 coronary arteries in 44 consecutive patients underwent beta brachytherapy with serial intravascular ultrasound studies. Vessel, lumen, and stent cross-sectional area were measured at 1-mm steps. Based on an interpolated reference cross-sectional area, each cross section was assessed as overdilated (lumen cross-sectional area>interpolated reference cross-sectional area) or not overdilated (lumen cross-sectional area <interpolated reference cross-sectional area).

RESULTS

Overall, 502 sections were overdilated and 673 sections were not. Overdilated sections had a larger final lumen cross-sectional area (8.02+/-1.98 vs. 6.90+/-2.23 mm2, P<.001) and more recurrent neointimal hyperplasia (1.59+/-2.17 vs. 0.31+/-1.79 mm2, P<.001), but a smaller follow-up area stenosis (-1.03+/-32.99% vs. 22.15+/-20.75%, P<.001). This was especially true in smaller arteries (angiographic reference<3.0 mm) where larger follow-up lumen cross-sectional area and a corresponding smaller area stenosis were present (5.38+/-1.98 vs. 4.84+/-1.88 mm2 and 6.90+/-31.57% vs. 28.61+/-21.86%, P<.01 and P<.001, respectively).

CONCLUSIONS

Especially in small arteries, the strategy of acute lumen overdilation during balloon angioplasty prior to beta vascular brachytherapy treatment of ISR lesions has a favorable long-term result.

Intravascular ultrasound in patients with challenging in-stent restenosis: importance of precise stent visualization

Intravascular ultrasound (IVUS) is widely used to optimize stent (ST) implantation. However, its value to guide therapy in challenging cases of in-stent restenosis (ISR) is not well established. We present 3 patients with complex ISR where IVUS interrogation was useful: (a) to readily identify the ST "entry door," (b) to accurately detect ST malapposition, (c) to measure the extent of ST protrusion out from its deployed position, and (d) to guide and optimize therapy. Thus, due to its unique ability to visualize the complete structure of the underlying ST, IVUS constitutes a superb diagnostic tool in patients with ISR, especially in challenging anatomic settings.

Long-Term Outcomes After Stenting of Bifurcation Lesions With the “Crush” Technique

OBJECTIVES

The purpose of this study was to evaluate predictors of an adverse outcome after "crush" bifurcation stenting.

BACKGROUND

The "crush" technique is a recently introduced strategy with limited data regarding long-term outcomes.

METHODS

We identified 231 consecutive patients treated with drug-eluting stent implantation with the "crush" technique for 241 de novo bifurcation lesions. Clinical follow-up was obtained in 99.6%.

RESULTS

The in-hospital major adverse cardiac event (MACE) rate was 5.2%. At 9 months, 10 (4.3%) patients had an event consistent with possible post-procedural stent thrombosis. Survival free of target lesion revascularization (TLR) was 90.3%; the only independent predictor of TLR was left main stem (LMS) therapy (odds ratio [OR] 4.97; 95% confidence interval [CI] 2.00 to 12.37, p = 0.001). Survival free of MACE was 83.5% and independent predictors of MACE were LMS therapy (OR 3.79; 95% CI 1.76 to 8.14, p = 0.001) and treatment of patients with multivessel disease (OR 4.21; 95% CI 0.95 to 18.56, p = 0.058). Angiographic follow-up was obtained in 77% of lesions at 8.3 +/- 3.7 months. The mean late loss of the main vessel and side branch were 0.30 +/- 0.64 mm and 0.41 +/- 0.67 mm, respectively, with binary restenosis rates of 9.1% and 25.3%. Kissing balloon post-dilation significantly reduced the side branch late lumen loss (0.24 +/- 0.50 mm vs. 0.58 +/- 0.77 mm, p < 0.001).

CONCLUSIONS

The crush technique of bifurcation stenting with drug-eluting stents is associated with favorable outcomes for most lesions; however, efficacy appears significantly reduced in LMS bifurcations, and further research is needed before the technique can be routinely recommended in this group. Furthermore, the incidence of possible stent thrombosis is of concern and requires further investigation. Kissing balloon post-dilatation is mandatory to reduce side branch restenosis.

Intravascular Ultrasound in the Current Percutaneous Coronary Intervention Era

The use of intravascular ultrasound (IVUS) in the cardiac catheterization laboratory has continued to evolve since its introduction nearly 15 years ago. In this review, the authors discuss the current strategies regarding the use of this imaging modality during percutaneous coronary interventions. Although routine IVUS guidance of interventions is unnecessary, the tomographic perspective provided by this modality can be very informative in selected cases. It remains unknown whether the use of emerging IVUS-based technologies such as elastography or spectral analysis is feasible for identification of vulnerable plaques.