Large Stent Research Articles

Compression, distortion and dislodgement of large caliber stents in congenital heart defects caused by cardiopulmonary resuscitation: a case series and review of the literature

Stenting of vascular, extracardiac or lately intracardiac stenosis has become an established interventional treatment for a variety of problems in congenital or acquired heart disease. Most stent procedures are completed successfully and the long-term outcome is favorable in the majority of cases. Stent collapse or deformation is a well recognized entity in peripheral stents and can be attributed to insufficient radial force; it can also be attributed to excessive external forces, like deformation of stents in the right ventricular outflow tract, where external compression is combined with continuous movement caused by the beating heart. The protection of the thoracic cage may prove to be insufficient in extraordinary circumstances, such as chest compression in trauma or cardiopulmonary resuscitation (CPR). In this case series, we describe three patients in whom large endovascular stents were placed to treat significant stenosis of the aorta, the aortic arch or the venous system of the inferior vena cava close to the atrium. In all patients, CPR was necessary during their clinical course for various reasons; after adequate CPR, including appropriate chest compression all patients survived the initial resuscitation phase. Clinical, echocardiographic as well as radiologic re-evaluation after resuscitation revealed significant stent distortion, compression, displacement or additional vascular injury. The possibility of mechanical deformation of large endovascular stents needs to be considered and recognized when performing CPR; if CPR is successful, immediate re-evaluation of the implanted stents--if possible by biplane fluoroscopy--seems mandatory.

The Odyssey of TAVR from concept to clinical reality.

On 16 April 2002, my colleagues and I performed, in an inoperable and desperately ill man with critical calcific aortic stenosis (AS), the first clinical percutaneous implantation of an aortic valve bioprosthesis. As of 2013, more than 80,000 patients have been treated; and transcatheter aortic valve replacement (TAVR), so strongly criticized by all the experts throughout the early years, continues to grow in parallel with its constant technological improvements. Transcatheter aortic valve replacement can now be recognized as a medical breakthrough. It is a revolutionary technology that meets an unfulfilled clinical need for a common disease, is validated by rigorous evidence-based studies, and is applicable worldwide. We report here the main phases of this 20-year odyssey and briefly consider the prospects of TAVR, which remains in continuous development.

Role of endoscopic stents and selective minimal access drainage in oesophageal leaks: feasibility and outcome

Leaks following oesophageal surgery are considered to be amongst the most dreaded complications and contributory to postoperative mortality. Controversies still exist regarding the best option for the management of oesophageal leaks due to lack of standardized treatment protocols. This study was designed to analyse the feasibility outcome and complications associated with placement of removable, fully covered, self-expanding metallic stents for oesophageal leaks with concomitant minimally invasive drainage when appropriate. The study group included 32 patients from a prospectively maintained database of oesophageal leaks, with the majority being anastomotic leaks after minimally invasive oesophagectomy (n = 28), followed by laparoscopic cardiomyotomy (n = 3) and extended total gastrectomy (n = 1). The procedures took place between March 2007 and April 2013. Most patients had an intrathoracic leak (n = 22), with a mean time to detection of the leak following surgery of 7.50 days (SD = 2.23). Subsequent to endoscopic stenting, enteral feeding via a nasojejunal tube was started on the second day and oral feeding was delayed until the 14th day (n = 31). Six patients underwent thoracoscopic (n = 5) or laparoscopic drainage (n = 1) along with stenting for significant mediastinal and intra-abdominal contamination. The stent migration rate of our study was 8.54%. The overall success in terms of preventing mortality was 96%. Endoscopic stenting should be considered a primary option for managing oesophageal leaks. Delayed oral intake may reduce the incidence of stent migration. Larger stents (bariatric or colorectal stents) serve as a useful option in case of migrated stents. Combined minimally invasive procedures can be safely adapted in appropriate clinical circumstances and may contribute to better outcomes.

Intervention in Benign Biliary Stricture and Biliary Leak

: Benign causes of biliary obstruction are often iatrogenic in nature, and most commonly result from inadvertent damage to the biliary tree during surgical procedures, particularly laparoscopy. Benign biliary obstruction may be associated with trauma, inflammatory processes due to stone disease or pancreatitis, surgery with biliary-enteric anastomoses, liver transplantation, sphincter of Oddi dysfunction, and as a late complication of the treatment of other intra-abdominal processes. The percutaneous treatment of benign biliary strictures by dilatation has a success rate ranging from 67 to 90%, which is higher than that of endoscopic treatment. Common complications of percutaneous biliary drainage and intervention include hemorrhage from puncture of the portal vein or hepatic artery, pleural or gallbladder puncture, injury to bowel or kidney, and sepsis. Placement of metallic stents in the BBS has been tried with no long term promising results. Metallic stents should only be considered for failed attempts at surgical repair. Development of self-expandable covered stents specifically designed to be removed at a later date may change current management strategies. Treatment with covered metal stents or bio absorbable stents warrants further evaluation. Endoscopic biliary sphincterotomy (EBS) is a first-line therapy for various pancreaticobiliary diseases. The endoscopic management of benign biliary diseases typically consists of dilation and insertion of one or more plastic stents followed by elective stent exchange every 3 months to avoid cholangitis caused by stent clogging. Sequential placement of multiple, large diameter stents in patients with distal common bile duct stenosis secondary to chronic pancreatitis appears to be superior to single stent placement and may provide good long-term benefits.

Meta-Analysis of Outcomes After Intravascular Ultrasound–Guided Versus Angiography-Guided Drug-Eluting Stent Implantation in 26,503 Patients Enrolled in Three Randomized Trials and 14 Observational Studies

There are conflicting data regarding the benefit of intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) over angiography-guided PCI. Since the last meta-analysis was published, several new studies have been reported. We performed a comprehensive meta-analysis to evaluate the clinical impact of IVUS-guided PCI with drug-eluting stent compared with conventional angiography-guided PCI. This meta-analysis included 26,503 patients from 3 randomized and 14 observational studies; 12,499 patients underwent IVUS-guided PCI and 14,004 underwent angiography-guided PCI. Main outcome measures were total mortality, myocardial infarction (MI), stent thrombosis, and target lesion revascularization (TLR). IVUS-guided PCI was significantly associated with more stents, longer stents, and larger stents. Regarding clinical outcomes, IVUS-guided PCI was associated with a significantly lower risk of TLR (odds ratio [OR] 0.81, 95% confidence interval [CI] 0.66 to 1.00, p=0.046). In addition, the risk of death (OR 0.61, 95% CI 0.48 to 0.79, p<0.001), MI (OR 0.57, 95% CI 0.44 to 0.75, p<0.001), and stent thrombosis (OR 0.59, 95% CI 0.47 to 0.75, p<0.001) were also decreased. In conclusion, our meta-analysis demonstrated that IVUS-guided PCI was associated with lower risk of death, MI, TLR, and stent thrombosis after drug-eluting stent implantation.

Optimal incentive contracts for knowledge workers

We study optimal incentive provision for “knowledge workers”, a crucial resource for many organizations. We augment a standard moral-hazard framework to reflect two key patterns: First, retention is a challenge because workers are free to leave; thereby harming their employer. Second, the value of the worker׳s outside option might depend on effort on the job. Optimal contracts that retain workers exhibit properties such as first-best effort and surplus, or non-responsiveness to changes in underlying conditions. Due to large rents, full retention is, however, costly for employers. Hence, even when socially inefficient, separation might occur in equilibrium.

Finite Element Modeling of A Novel Self-Expanding Endovascular Stent Method in Treatment of Aortic Aneurysms

A novel large self-expanding endovascular stent was designed with strut thickness of 70 μm × 70 μm width. The method was developed and investigated to identify a novel simpler technique in aortic aneurysm therapy. Stage 1 analysis was performed after deploying it in a virtual aneurysm model of 6 cm wide × 6 cm long fusiform hyper-elastic anisotropic design. At cell width of 9 mm, there was no buckling or migration of the stent at 180 Hg. Radial force of the stents was estimated after parametric variations. In stage 2 analysis, a prototype 300 μm × 150 μm stent with a cell width of 9 mm was chosen, and it was evaluated similarly after embedding in the aortic wall, and also with a tissue overgrowth of 1 mm over the stent. The 300/150 μm stent reduced the peak wall stress by 70% in the aneurysm and 50% reduction in compliance after embedding. Stage 3 analysis was performed to study the efficacy of stents with struts (thickness/width) 70/70, 180/100 and 300/150 μm after embedding and tissue overgrowth. The adjacent wall stresses were very minimal in stents with 180/100 and 70/70 μm struts after embedding. There is potential for a novel stent method in aortic aneurysm therapy.

Sole Stenting with Large Cell Stents for Very Small Ruptured Intracranial Aneurysms

A flow-diverting stent such as the Pipeline embolization device (PED, ev3 Endovascular, Plymouth, MN, USA) and Silk flow-diverting stent (Balt Extrusion, Montmorency, France) offers an acceptable alternative for the treatment of difficult aneurysms according to their morphologies, including giant, wide-necked, fusiform, and blister types. However, complications arising from the use of these stents have frequently been reported including several cases of branch artery occlusion and delayed occlusion of the stented parent vessel shortly after antiplatelet medications were discontinued, highlighting the potential need for long-term antiplatelet therapy, and disastrous bleeding complications in unruptured aneurysm. In addition, these microcell stents are difficult to use in distal aneurysms located over the ICA bifurcation and basilar tip because of the stiffness of the device, and perforating vessel occlusion is more likely to occur due to the characteristics of the stent. Before the era of flow-diverting microcell stents, large cell intracranial stents like the Neuroform stent (Boston Scientific/Target Therapeutic, Fremont, CA, USA) and Enterprise stent (Cordis Neurovascular, Miami, FL, USA) without coiling were used to provide flow-diverting effects for complex intracranial aneurysms. Sole stenting has been used even in cases of ruptured aneurysm, with patients on different antiplatelet medications. However, no single endovascular institute has embraced sole stenting using large cell intracranial stents as a systemized treatment for ruptured intracranial aneurysms. Here we designed this study to evaluate the possibility of safely treating very small aneurysms using one or two stents without coiling during the period of subarachnoid hemorrhage (SAH). This retrospective study was conducted with eight patients who had rupture of very small intracranial aneurysms (less than 3 mm in size). All were treated using the Neuroform and the Enterprise stents; there was single stenting in five, in-stent telescopic stenting in two, and Y-configured stenting in one. The angiographic results with clinical outcomes were collected and analyzed. Complete aneurysm obliteration was observed in three cases, and size reduction or stable angiographic findings was found in five cases on the last follow-up angiography. No growing aneurysm or rebleeding was found on any follow-up angiography. Thromboembolic complications were found in one patient. It is difficult to make conclusions on the long-term efficacy of this technique with such a small number of cases, however sole stenting with a large cell intracranial stent for the treatment of very small aneurysms may be used safely as an alternative treatment even during an episode of SAH.

A Multicenter Randomized Controlled Trial of Malignant Gastric Outlet Obstruction: Tailored Partially Covered Stents (Placed Fluoroscopically) versus Standard Uncovered Stents (Placed Endoscopically).

The aim of our study is to compare the efficacy and safety of “outlet-shape” tailored stents with standard stents for the management of distal gastric cancer causing gastric outlet obstructions (GOOs) with varying gastric cavity shapes and sizes. To determine the shape and size of the GOOs, stomach opacifications were performed using contrast media before stenting. Two basic shapes of the residual cavity of the proximal GOO were observed: cup shaped or approximately cup shaped and funnel shaped or approximately funnel shaped. Other shapes were not found. In the GOO tailored group, the size and shape of the proximal ends of the tailored stent were suited for the residual cavity of the proximal GOO. The tailored stents included large cup-shaped stents and large funnel-shaped stents. GOO tailored covered stents led to less restenosis and reintervention rates compared to standard uncovered stents but with the same survival.

Does manual thrombus aspiration help optimize stent implantation in ST-segment elevation myocardial infarction?

To evaluate the impact of thrombus aspiration (TA) on procedural outcomes in a real-world ST-segment elevation myocardial infarction (STEMI) registry. From May 2006 to August 2008, 542 consecutive STEMI patients referred for primary or rescue percutaneous coronary intervention were enrolled and the angiographic results and stent implantation characteristics were compared according to the performance of manual TA. A total of 456 patients were analyzable and categorized in TA group (156 patients; 34.2%) and non-TA (NTA) group (300 patients; 65.8%). Patients treated with TA had less prevalence of multivessel disease (39.7% vs 54.7%, P = 0.003) and higher prevalence of initial thrombolysis in myocardial infarction flow < 3 (P < 0.001) than NTA group. There was a higher rate of direct stenting (58.7% vs 45.5%, P = 0.009), with shorter (24.1 ± 11.8 mm vs 26.9 ± 15.7 mm, P = 0.038) and larger stents (3.17 ± 0.43 mm vs 2.93 ± 0.44 mm, P < 0.001) in the TA group as compared to NTA group. The number of implanted stents (1.3 ± 0.67 vs 1.5 ± 0.84, P = 0.009) was also lower in TA group. In an "all-comers" STEMI population, the use of TA resulted in more efficient procedure leading to the implantation of less number of stents per lesion of shorter lengths and larger sizes.

Asset freezing, corporate political resources and the Tullock paradox

In 1967, Gordon Tullock asked why firms do not spend more on campaign contributions, despite the large rents that could be generated from political activities. We suggest in this paper that part of the puzzle could come from the fact that one important type of political activity has been neglected by the literature which focuses on campaign contributions or political connections. We call this neglected activity “asset freezing”: situations in which firms delay lay-offs or invest in specific technologies to support local politicians’ re-election objectives. In doing so, firms bear a potentially significant cost as they do not use a portion of their economic assets in the most efficient or productive way. The purpose of this paper is to provide a first theoretical exploration of this phenomenon. Building on the literature on corporate political resources, we argue that a firm's economic assets can be evaluated based on their degree of “political freezability,” which depends on the flexibility of their use and on their value for policy-makers. We then develop a simple model in which financial contributions and freezing assets are alternative options for a firm willing to lawfully influence public policy-making, and derive some of our initial hypotheses more formally.

Should Proximal LAD be treated differently? Insights from a large DES stent registry

The current revascularization treatment recommendation is different according to lesion location and a higher recommendation is given to surgery for proximal LAD (pLAD) lesions over PCI. This is based on previous studies and expert opinion. We aimed to investigate whether indeed there is a difference in outcome with respect to LAD lesion location while using a drug eluting stent (DES). The NOBORI-2 trial, enrolled 3067 consecutive patients in 125 centers who were treated with DES for single and multivessel disease. We compared 834 [27.2%] patients who underwent PCI of the pLAD as part of their revascularization, to 2203 [71.8%] patients in which stenting to other lesion(s) but not the pLAD was performed. The pLAD group had lower incidence of hypertension, peripheral vascular disease, prior PCI and CABG, but had more lesions treated [1.55 ± 0.8 vs. 1.35 ± 0.6], more stents implanted [1.98 ± 1.2 vs. 1.66 ± 1.0] and longer overall stent length [31.8 ± 20.2 vs. 28.2 ± 17.8 mm]. There was no difference in the occurrence of the primary endpoint [cardiac death, myocardial infarction and target lesion revascularization] at 1 or 2 years of follow up between the pLAD and non pLAD [6.0% vs. 4.6%, p=0.14 and 7.7% vs. 6.6%; p=0.22, respectively]. The relief from anginal symptoms was similar. Multivariate analysis showed that pLAD location was not a variable that predicted MACE or TLF. Stent thrombosis rate was similar. When considering PCI with DES, there is no difference in outcome between patients with and without proximal LAD lesions.

Peak oil supply or oil not for sale?

The restrictions imposed by climate change are inevitable and will be exerted either via precautionary mitigation of (mainly energy-related) CO2 emissions or via irreversible impacts on ecosystems and on human habitats. Either way, oil markets are bound to incur drastic shrinking. Concern over peak oil supply will crumble when the irrevocable peak oil demand is created. Replacing oil in the world's energy economies requires redirected market forces, notably in the form of steadily increasing oil end-use prices. Yet, thus far, crude oil prices have obeyed the market fundamentals of expanding-contracting demand and oligopolistic supply. A hockey stick supply curve supports high sales prices, providing large rents to submarginal sources. Cutting oil demand and maintaining high prices implies reducing the supply hockey stick's length by curtailing some oil producers. In such a scenario, the alliances, goals, and tactics of oil geopolitics are set to change. We identify a distribution over friendly and hostile oil suppliers, with others drifting in between the two sides. Conflicts and warfare are less aimed at conquering oil fields for exploitation than at paralyzing production capabilities of opponents or of unreliable transient sources. Covert warfare and instigation of internal conflicts are likely tactics to exhaust hostile opponents.

Implantation of new cobalt-chromium stents in the treatment of aortic coarctation

Purpose: Stenting in Coarctation of the Aorta (CoA) has been performed with different stents. Recently new bare metal stent made of a Cobalt-Chromium (Co-Cr) alloy was introduced to clinical practice. They have hybrid open/closed cell design and are laser cut. We evaluated immediate result and midterm follow-up of implantation of this stents in the management of CoA at a single tertiary care center. Methods: Thirty five new type Co-Cr stents were implanted in 35 patients (pts): 30 with native CoA and 5 with recurrent after previous surgery (ReCoA). All had arterial hypertension in upper limbs, absent or weak femoral puls and continuous flow in abdominal aorta in Doppler examination. Mean patient age was 28,3±15,6 (ranged from 9 to 65) years. The stents were manually mounted on high pressure balloons and delivered through 10 to 14 Fr Mullins sheaths using a conventional femoral approach. Andrastent XL have expansion range till 25 mm, Andrastent XXL till 32 mm and both are different available lengths (from 13 till 57 mm). Results: All procedures were successful (no migration, proper expantion, no aorta dissection/rupture) – 15 XL Andrastents and 20 XXL were applied. In one pt (49 years old man) with severe secondary LV failure (EF 15%) the procedure was performed urgently during cardiogenic shock with good clinical result. The systolic gradient across the native CoA decreased from a mean 48,3±20,2 before to 11,9±10,2 mm Hg after the procedure and in case of ReCoA from 37,8±20,7 before to a mean 9,7±12,4 mm Hg after the procedure. The mean fluoroscopy time was 6,1±2,3 min. Procedural outcome remained favorable during mean follow-up 1,2±0,8. No aneurysm formation, stent fracture, dislocation were observed after the procedure in follow-up. Planned redilatation of implanted stent was performed between 4 and 14 months in 9 patients. In another 8 pts controlled angio CT was performed. Conclusions: Implantation of new large cobalt-chromium stents are very good therapeutical option for the treatment of native and recurrent CoA. Its strong radial force, flexibility and good radio-opacity is advantageous in implantation in CoA.

Impact of stent diameter and length on in-stent restenosis after drug eluting stent versus bare metal stent implantation in patients needing large coronary stents

Introduction: The advantage of drug eluting stents (DES) compared to bare metal stents (BMS) is small for the the risk of in-stent-restenosis (ISR) in short lesions of large coronary arteries. Therefore, the British National Institutes of Clinical Excellence (NICE) guidelines recommend to use BMS instead of DES in lesions 3mm diameter. However, no dedicated trial has tested this question. We analysed the impact of stent length and stent diameter on ISR in the BASKET-PROVE study population. Methods: In the multicentre randomized BASKET-PROVE study we compared BMS vs. DES regarding target vessel revascularization (TVR) rates in large coronary arteries (needing ≥3mm stents) resulting in significantly lower 2-year TVR rates in the DES group. For this retrospective subgroup analysis two experienced interventionalists blinded to stent type reviewed all angiographic films for the presence of ISR. We used a mixed-effects Cox survival model to analyse the impact of stent length and stent diameter on ISR on a basis, with ISR being defined as luminal narrowing >50% by visual assessment. Results: 2312 patients with a total of 3278 stented segments were included in the analysis (mean age 63.7±10.9 years; 24.4% female). 123 patients had at least one re-angiography during the two years follow-up due to recurrent ischemia. A total of 75 ISR in 63 patients were observed (mean age 61.9±11.1 years). ISR was significantly more frequent in segments with a BMS (5.3%) compared to segments with a DES (0.74%; HR = 6.18, p<0.001). Based on the Cox analysis, the strongest predictor of ISR was the use of a BMS (hazard ratio (HR)) 6.74; p<0.001). There was a decreased risk of ISR per 1mm increase in stent diameter (HR of 0.30, p=0.003). The HR for stent length per segment was 1.02 (p=0.02; CI= 1.0-1.04) indicating a 2% increased risk of ISR per 1mm increase in stent length. Co-factors like renal failure or diabetes mellitus had no significant effect on ISR. The HR for ISR in patients with stent diameter >3mm and stent length <15mm was not significantly different between the DES and the BMS group although the event rate in this subgroup was low (2.0% with BMS, 1.4% with DES, p=NS). Conclusion: The risk of ISR in patients receiving stents in large coronary arteries is low. Nevertheless, even in patients in need of stents ≥3.0mm, the strongest predictor of ISR was the use of a BMS. Other co-factors like renal failure or DM are not associated with ISR in this population. Alltogether, these findings challenge the restriction of NICE to use BMS instead of DES in vessels >3.0mm.

Abstract 348: A Novel Self Expanding Stent Technology for treatment of Aortic Aneurysms - Finite Element Analysis

Background: To investigate a novel self-expanding Nitinol stent model in treatment of aortic aneurysms. Methods: A novel large self-expanding Nitinol stent method was designed with strut thickness of 70µM x 70µM width and it was deployed in a virtual aneurysm model of 6cm wide x 6cm long fusiform hyper-elastic anisotropic model. At cell width of 9mm, there was no buckling of the deployed stent. The peak wall stress and stress-strain properties of the aortic aneurysm wall; and the adjacent normal segments of aorta were studied at various pressures with or without stent. The radial force of the stents was tested after parametric variations. A prototype 300µM x 150µM stent with cell width of 9mm was evaluated similarly for maximal stress distribution after embedding in the aortic wall and with a tissue overgrowth of 1mm over the stent. Results: The 300µM x 150µM stent reduced the peak wall stress by 70% in the aneurysm and 50% reduction in compliance after a tissue overgrowth of 1mm over the stent struts. Conclusions: There is potential for a novel Nitinol based self-expanding stent in the therapy of aortic aneurysms.

Angioscopically apparent large thrombus and uncovered stent struts 6 months after late stent thrombosis of a paclitaxel-coated nitinol drug-eluting stent implanted in the superficial femoral artery

A 74-year-old woman complained of claudication due to in-stent restenosis of bare-metal stents in the right superficial femoral artery, and two Zilver PTXs were deployed. However, hemarthrosis developed, and aspirin and clopidogrel were discontinued. Thirty-six days later, she suddenly felt rest pain in her right leg. Angiography revealed total occlusion at the Zilver PTX implantation site, demonstrating late stent thrombosis. Aspiration and thrombolysis yielded adequate flow and symptom resolution. Follow-up catheterization was scheduled 6months later. While the Zilver PTX stents were angiographically patent, angioscopy demonstrated a large red thrombus and uncovered stent struts. Therefore, dual antiplatelet therapy was continued.

Angioplasty of acquired pulmonary vein stenosis using covered stent

One of the most serious complications post-catheter ablation of atrial fibrillation is the development of pulmonary vein stenosis. Controversy currently exists about the optimal treatment approach. The use of balloons and larger stents (~10 mm) results in more optimal outcome than just balloon angioplasty alone; however, even with stent implantation, recurrent restenosis may occur in 30 to 50% of patients. We report the case of a 28-year-old man who developed recurrent left inferior pulmonary vein stenosis following radiofrequency ablation for atrial fibrillation. This was initially stented with good result but soon after developed restenosis and required balloon angioplasty. Following the third episode of restenosis, stenting of the pulmonary vein was performed using a covered stent. The pulmonary vein has remained patent for the last 5 years.

Avaliação muito tardia do uso de stents farmacológicos para tratamento de pacientes com lesões em enxertos de veia safena: experiência de uma década do Registro DESIRE

INTRODUÇÃO: A intervenção coronária percutânea (ICP) em pontes de safena ainda representa um desafio à cardiologia intervencionista, pelas complicações agudas e pela escassez de dados referentes à efetividade tardia dos stents farmacológicos (SFs). MÉTODOS: Entre maio de 2002 e janeiro de 2013, pacientes submetidos a ICP com SF no Hospital do Coração foram incluídos no Registro DESIRE. Avaliamos os resultados de pacientes submetidos a ICP em pontes de safena (grupo 1), que foram comparados aos submetidos a ICP em vasos nativos (grupo 2). RESULTADOS: De um total de 4.655 pacientes, 311 foram incluídos no grupo 1 e 4.344, no grupo 2. O grupo 1 contou com pacientes mais idosos (68,4 ± 9,7 anos vs. 64 ± 11,2 anos; P < 0,01), com mais pacientes do sexo masculino (87,1% vs. 76,7%; P < 0,01) e com maior incidência de comorbidades. Angina instável foi a apresentação clínica mais frequente nesse grupo. Pacientes do grupo 1 receberam stents de maior calibre (3,18 ± 1,11 mm vs. 2,86 ± 0,43 mm; P < 0,01) e foram submetidos menos frequentemente a pré-dilatação (36,3% vs. 50,7%; P < 0,01) e a pós-dilatação (38,3% vs. 58,4%; P < 0,01). Apresentaram mais infarto agudo do miocárdio não-fatal na fase hospitalar (11,3% vs. 4,1%; P < 0,01) e mais eventos cardiovasculares adversos maiores na fase tardia (32,8% vs. 13,9%; P < 0,01), à custa de óbito cardíaco (7,7% vs. 3,2%; P = 0,02) e de revascularização da lesão-alvo (9% vs. 4,3%; P < 0,01). Trombose definitiva do stent foi mais frequente no grupo 1 (3,5% vs. 1%; P < 0,01). CONCLUSÕES: A despeito do inquestionável benefício dos SFs nos resultados tardios de ICP em pacientes complexos, o tratamento de pacientes com lesões em pontes de safena ainda permanece um desafio, com resultados agudos e tardios menos favoráveis que os de pacientes com lesões em vasos nativos.

Impact of stent mis-sizing and mis-positioning on coronary fluid wall shear and intramural stress

Stent deployments with geographical miss (GM) are associated with increased risk of target-vessel revascularization and periprocedural myocardial infarction. The aim of the current study was to investigate the underlying biomechanical mechanisms for adverse events with GM. The hypothesis is that stent deployment with GM [longitudinal GM, or LGM (i.e., stent not centered on the lesion); or radial GM, RGM (i.e., stent oversizing)] results in unfavorable fluid wall shear stress (WSS), WSS gradient (WSSG), oscillatory shear index (OSI), and intramural circumferential wall stress (CWS). Three-dimensional computational models of stents and plaque were created using a computer-assisted design package. The models were then solved with validated finite element and computational fluid dynamic packages. The dynamic process of large deformation stent deployment was modeled to expand the stent to the desired vessel size. Stent deployed with GM resulted in a 45% increase in vessel CWS compared with stents that were centered and fully covered the lesion. A 20% oversized stent resulted in 72% higher CWS than a correct sized stent. The linkages between the struts had much higher stress than the main struts (i.e., 180 MPa vs. 80 MPa). Additionally, LGM and RGM reduced endothelial WSS and increased WSSG and OSI. The simulations suggest that both LGM and RGM adversely reduce WSS but increase WSSG, OSI, and CWS. These findings highlight the potential mechanical mechanism of the higher adverse events and underscore the importance of stent positioning and sizing for improved clinical outcome.