Paclitaxel-Eluting Stents for Chronically Occluded Saphenous Vein Grafts (EOS) Study

Objectives: The aim of this study was to report the feasibility, short- and medium-term results of percutaneous coronary intervention (PCI) on saphenous vein graft (SVG) chronic total occlusions (CTO) using paclitaxel-eluting stents (PES).
Background: In postbypass patients, PCI on SVG CTO, rather than native vessel CTO, is another treatment option. However, the acute procedural and medium-term outcomes are unknown.
Methods: Twenty-two consecutive, symptomatic postbypass patients underwent PCI on SVG CTO; angiographic success was seen in 16 patients (73%). The successful cases were evaluated at 1 year; restudy angiography was performed at 11 ± 5 months in 15 patients (94%).
Results: The patients had a mean age of 73 years with predominance of male (68%); the mean SVG age was 14 years. On average, patients received 3.4 PESs per lesion; the stent size was 3.5 ± 0.4 mm with a total stent length of 98 ± 34 mm. The use of embolic protection devices and glycoprotein IIb/ IIIa inhibitors was observed in 6 (38%) and 5 (31%) patients, respectively. The in-hospital major adverse cardiac event (MACE) was 13%, accountable by 2 patients with postprocedure myocardial infarction. At follow-up, 6 patients had angiographic restenosis (40%); there was 1 noncardiac death and 3 target vessel revascularizations. The 1-year MACE was 25%; the graft survival free of occlusion and revascularization was 56%.
Conclusions: PCI on SVG CTO is a feasible approach with a fairly high success and low in-hospital complication. However, it is associated with a relatively high angiographic restenosis and MACE at 1 year. (J Interven Cardiol 2010;23:40–45)     

Endoscopic Treatment of Benign Biliary Strictures Using Covered Self-Expandable Metal Stents (CSEMS)

Background and Aims

Traditional endoscopic management of benign biliary strictures (BBS) consists of placement of one or more plastic stents. Emerging data support the use of covered self-expandable metal stents (CSEMS). We sought to assess outcome of endoscopic temporary placement of CSEMS in patients with BBS.

Methods

This was a retrospective study of CSEMS placement for BBS between May 2005 and July 2012 from two tertiary care centers. A total of 145 patients (81 males, median age 59 years) with BBS were identified; 73 of which were classified as extrinsic and were caused by chronic pancreatitis, and 70 were intrinsic. Main outcome measures were resolution of stricture and adverse events (AEs) due to self-expandable metal stents (SEMS)-related therapy.

Results

Fully covered and partially covered 8–10 mm diameter SEMS were placed and subsequently removed in 121/125 (97 %) attempts in BBS (failure to remove four partially covered stents). Stricture resolution occurred in 83/125 (66 %) patients after a median stent duration of 26 weeks (median follow-up 90 weeks). Resolution of extrinsic strictures was significantly lower compared to intrinsic strictures (31/65, 48 % vs. 52/60, 87 %, p = 0.004) despite longer median stent duration (30 vs. 20 weeks). Thirty-seven AEs occurred in 25 patients (17 %), with 12 developing multiple AEs including cholangitis (n = 17), pancreatitis (n = 5), proximal stent migration (n = 3), cholecystitis (n = 2), pain requiring SEMS removal and/or hospitalization (n = 3), inability to remove (n = 4), and new stricture formation (n = 3).

Conclusions

Benign biliary strictures can be effectively treated with CSEMS. Successful resolution of biliary strictures due to extrinsic disease is seen significantly less often than those due to intrinsic disease. Removal is successful in all patients with fully covered SEMS.     

Silicone-Covered Metal Stents (An In Vitro Evaluation for Biofilm Formation and Patency)

Self-expanding metal stents are being used morecommonly to prevent biliary tract obstruction.Silicone-covered self-expanding metal stents (Wallstent,Schneider, Inc.) have been developed to prevent tumor ingrowth. Biofilm formation and occlusionmaterial in siliconecovered self-expanding metal stentscompared to standard polyethylene stents were examinedin an in vitro model. Matched pairs of polyethylene and silicone-covered metal stents were perfusedwith infected bile for 8, 12, and 16 weeks at a rate of0.5 cc/min at 37°C. Two reservoirs fitted withsilicone-covered metal stents had ampicillin/sulbactam added and were perfused for 16 weeks. Thestents were then analyzed by scanning electronmicroscopy and light microscopy for biofilm formationand presence of occlusion material. The twoampicillin/sulbactam-treated stents showed no biofilm formation. Biofilm wasseen on all of the remaining stents. There was adifference in occlusion thickness between the 8- and16-week polyethylene stents, and no difference between the biofilm thickness at 8, 12, or 16 weeks inthe silicone-covered metal stents. Silicone-coveredself-expanding metal stents will likely extend patencyrates in malignant obstructive jaundice by providing a larger lumen for bile flow and allowingcyclical antibiotics to prevent bacterial biofilmformation.     

Estrogen-Eluting Stents

Coronary stenting is routinely utilized to treat symptomatic obstructive coronary artery disease. However, the efficacy of bare metal coronary stents has been historically limited by restenosis, which is primarily due to excessive neointima formation. Drug-eluting stents (DES) are composed of a stainless steel backbone encompassed by a polymer in which a variety of drugs that inhibit smooth muscle cell proliferation and excessive neointima formation are incorporated. DES have significantly reduced the incidence of restenosis but are also associated with a small (~0.5% per year) but significant risk of late stent thrombosis. In that regard, estrogen-eluting stents have also undergone clinical evaluation in reducing restenosis with the additional potential benefit of enhancing reendothelialization of the stent surface to reduce stent thrombosis. Estrogen directly promotes vasodilatation, enhances endothelial healing, and prevents smooth muscle cell migration and proliferation. Due to these mechanisms, estrogen has been postulated to reduce neointimal hyperplasia without delaying endothelial healing. In animal studies, estrogen treatment was effective in decreasing neointimal hyperplasia after both balloon angioplasty and stenting regardless of the method of drug delivery. The first uncontrolled human study using estrogen-coated stents demonstrated acceptable efficacy in reducing late lumen loss. However, subsequent randomized clinical trials did not show superiority of estrogen-eluting stents over bare metal stents or DES. Further studies are required to determine optimal dose and method of estrogen delivery with coronary stenting and whether this approach will be a viable alternative to the current DES armamentarium.     

Absorbierbare Stents

Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal.The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated.Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion revascularization rate of 23.8% which was below the 30% cut point of the study protocol. No myocardial Q wave infarction or death were reported. The primary endpoint was reached.During the follow-up period, vasomotion was tested in some of the patients. The proof of principle was confirmed: restoration of vasomotion during acetylcholine testing.The development of the absorbable magnesium stent, which was pushed forward by B. Heublein, Hanover, Germany, has been successful and opens new possibilities for treatment of coronary arteries. Permanent foreign-body implantation is avoided allowing further revascularization procedures in the future, bypass grafting, and restoration of vasomotion. Even prophylactic stenting in nonsignificant stenosis, like vulnerable lesions, may become a regular procedure. Noninvasive coronary imaging by CT and MRI is now possible. Stenting of children and in peripheral arteries may become a standard procedure. Currently, the degradation process of the magnesium stent has to be prolonged, and the neointima proliferation rate has to be reduced so that the DREAM (Drug-Eluting Absorbable Magnesium Stent) concept of Ron Waksman, Washington, DC, USA, can be realized.     

Enterale Stents

Stenosis of the duodenum is a common complication of malignancy of the pancreatic head or the biliary system. The resulting gastroduodenal outlet obstruction has a significant morbidity and lowers the patient’s quality of life. In addition to the palliative surgical gastroenterostomy, the endoscopic application of enteral stents has been established as a treatment. This method is efficient for symptom relief and causes few complications. There is a lack of large prospective randomized studies comparing the two methods, but the palliative endoscopic method seems to be effective and efficient, and in advanced tumor stages, probably even superior to surgical gastroenterostomy.     

Rationale and design of the Drug‐Eluting Stents vs Bare‐Metal Stents in Saphenous Vein Graft Angioplasty (DIVA) Trial

VA Cooperative Studies Program #571 (DIVA) was designed to evaluate the efficacy of drug‐eluting stents (DES) for reducing aortocoronary saphenous vein bypass graft (SVG) failure when compared with bare‐metal stents (BMS) in participants undergoing stenting of de novo SVG lesions. Participants undergoing clinically indicated stenting of de novo SVG lesions were randomized in a 1:1 ratio to DES or BMS. Randomization was stratified by presence/absence of diabetes mellitus and the number of target SVG lesions (1 vs ≥2) within each participating site. At sites that did not routinely administer 12‐months of dual antiplatelet therapy after SVG stenting participants without acute coronary syndromes received 1 month of open‐label clopidogrel, followed by 11 months of clopidogrel for those assigned to DES and 11 months of placebo for those assigned to BMS. The primary endpoint was the 12‐month incidence of target‐vessel failure (defined as the composite of cardiac death, target‐vessel myocardial infarction, or target‐vessel revascularization). Secondary endpoints included the incidence of other clinical endpoints and the incremental cost‐effectiveness of DES relative to BMS. Due to lower‐than‐anticipated target‐vessel failure rates, target enrollment was increased from 519 to 762. The study had randomized 599 participants when recruitment ended in December 2015. The DIVA trial will provide clarity on the appropriate stent type for de novo SVG lesions.     

Long-term clinical outcomes of the Drug-Eluting Stents in the Real World (DESIRE) Registry

Background: Recently, cardiologists have treated more complex patients and lesions with drug-eluting stents (DES). However, long-term efficacy and safety of the off-label use of these new devices is yet to be demonstrated.
Methods: The Drug-Eluting Stents in the Real World (DESIRE) registry is a prospective, nonrandomized single-center registry with consecutive patients treated solely with DES between May 2002 and May 2007. The primary end-point was long-term occurrence of major adverse cardiac events (MACE). Patients were clinically evaluated at 1, 3, and 6 months and then annually up to 5 years.
Results: A total of 2,084 patients (2,864 lesions and 3,120 DES) were included. The mean age was 63.8 ± 11.5 years. Diabetes was detected in 28.9% and 40.7% presented with acute coronary syndrome. Cypher™ was the predominant DES in this registry (83.5%). Mean follow-up time was 2.6 ± 1.2 years and was obtained in 96.5% of the eligible patients. Target lesion revascularization (TLR) was performed in 3.3% of the patients. Q wave myocardial infarction (MI) occurred in only 0.7% of these patients and total stent thrombosis rate was 1.6% (n = 33). Independent predictors of thrombosis were PCI in the setting of MI (HR 11.2; 95% CI, 9.6–12.4, P = 0.001), lesion length (HR 4.6; 95% CI, 3.2–5.3, P = 0.031), moderate to severe calcification at lesion site (HR 13.1; 95% CI, 12.1–16.7, P < 0.001), and in-stent residual stenosis (HR 14.5; 95% CI, 10.2–17.6, P < 0.001).
Conclusion: The use of DES in unselected population is associated with long-term safety and effectiveness with acceptable low rates of adverse clinical events.