Late thrombosis in cypher stents after the discontinuation of antiplatelet therapy

Five-Year Impacts of Antithrombotic Therapy Based on 10-Year Clinical Outcomes of Cypher™ Stent Implantation

Introduction

Few researchers have investigated the optimal long-term antithrombotic therapy regimen, especially after first-generation drug-eluting stent (DES) use. This study aimed to evaluate the impact of mid-term antithrombotic therapy on long-term outcomes in patients treated with the first sirolimus-eluting coronary stent (Cypher™).

Methods

Between 2004 and 2009, 1021 patients underwent Cypher™ implantation at our institute; among them, 567 patients had available data on antithrombotic therapy at year 5. We assessed patients’ antithrombotic therapy at year 5 post Cypher™ implantation and examined their association with adverse events from year 5 to year 10 post Cypher™ implantation.

Results

Patients with dual-antiplatelet therapy (DAPT) at year 5 had significantly lower risk of stent thrombosis (ST) than those with single-antiplatelet therapy (SAPT) (hazard ratio [HR] 0.24, p = 0.034). The HR of major bleeding in DAPT, compared to SAPT, was high, but the difference was not significant (HR 1.72, p = 0.26). Risk of major bleeding was significantly higher in patients on oral anticoagulants (OAC) than in those in other groups (OAC/SAPT; HR 5.31, p = 0.0048, OAC/DAPT; HR 3.08, p = 0.022), without significant reduction in the risk of cardiovascular events.

Conclusions

The incidence of ST after Cypher™ implantation in patients with DAPT at year 5 was significantly lower than that in SAPT. However, the risk of bleeding was higher with DAPT than with SAPT. Moreover, the risk of major bleeding was significantly higher in patients on anticoagulant therapy than in other patients. New options for the use of antithrombotic drugs after percutaneous coronary intervention warrant further studies on the optimal antithrombotic therapy for first-generation DES.

Hemocompatibility of hyaluronan enhanced linear low density polyethylene for blood contacting applications

Despite their overall success, different blood-contacting medical devices such as heart valves, stents, and so forth, are still plagued with hemocompatibility issues which often result in the need for subsequent replacement and/or life-long anticoagulation therapy. Consequently, there is a significant interest in developing biomaterials that can address these issues. Polymeric-based materials have been proposed for use in many applications due to their ability to be finely tuned through manufacturing and surface modification to enhance hemocompatibility. In this study, we have developed a novel, hydrophilic biomaterial comprised of an interpenetrating polymer network (IPN) of hyaluronan (HA) and linear low density polyethylene (LLDPE). HA is a highly lubricous, anionic polysaccharide ubiquitously found in the human body. It is currently being investigated for a vast array of biomedical applications including cardiovascular therapies such as hydrogel-based regenerative cell therapies for myocardial infarction, HA-coated stents, and surface modifications of polyurethane and metals for use in blood-contacting implants. The aim of this study was to assess the in vitro thrombogenic response of the hydrophilic polymer surface, HA-LLDPE for future potential use as flexible heart valve leaflets. The results indicate that HA-LLDPE is non-toxic and reduces thromobogenicity as compared to LLDPE surfaces, asserting its feasibility for use as a blood-contacting biomaterial. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1964-1975, 2018.

Correlates and outcomes of late and very late drug-eluting stent thrombosis: results from DESERT (International Drug-Eluting Stent Event Registry of Thrombosis)

OBJECTIVES

The aim of this study was to identify clinical, procedural, and angiographic correlates of late/very late drug-eluting stent (DES) thrombosis as well as to determine the clinical outcomes of these events.

BACKGROUND

Late/very late DES thromboses are a poorly studied phenomenon, partly due to the relative infrequency of these events, even in large cohort studies.

METHODS

In the DESERT (International Drug-Eluting Stent Event Registry of Thrombosis), a retrospective, case-control registry, 492 cases of late/very late definite DES thrombosis from 21 international sites were matched in a 1:1 fashion with controls without stent thrombosis (ST). Controls were matched according to 2 criteria: same enrolling institution and date of initial DES implantation. Baseline and procedural variables were collected, and clinical follow-up was obtained for patients with ST as long as 1 year after the event. Offline quantitative coronary angiography was performed for a subset of 378 case-control pairs.

RESULTS

The majority of ST events occurred after 1 year (75%) and continued to occur for as long as 7.3 years. The clinical presentation of late/very late ST events was mainly myocardial infarction (66.7% ST-segment elevation myocardial infarction and 22.0% non-ST-segment elevation myocardial infarction); in-hospital mortality was 3.8%. A minority of patients (30%) with ST were receiving dual-antiplatelet therapy at the time of the event. Independent clinical correlates of late/very late ST were younger age, African-American race, current smoking, multivessel disease, longer stented length, overlapping stents, and percutaneous coronary intervention of vein graft lesions. Independent angiographic correlates for late/very late ST were lesions within the left anterior descending artery or a bypass graft, thrombus, and a larger residual diameter stenosis after the initial DES implantation. Despite the large sample of ST cases, all identified correlates of late/very late ST had weak associations with subsequent ST (all odds ratios <2.5).

CONCLUSIONS

Despite a large sample of ST cases and use of limited matching to maximize the identification of predictive factors associated with late/very late ST, the variables associated with the development of late/very late ST were only weakly predictive of subsequent events. Additionally, a relatively low observed mortality rate of ST in this series may reflect a different pathophysiology of these late/very late events compared with acute/subacute ST. (Drug Eluting Stent Registry of Thrombosis [DESERT]; NCT00812552).

Dual antiplatelet therapy over 6 months increases the risk of bleeding after biodegradable polymer-coated sirolimus eluting stents implantation: insights from the CREATE study

BACKGROUND

The optimal duration of dual antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation remains controversial. The primary aim of our study was to evaluate the impact of optimal DAPT duration on bleeding events between 6 and 12 months after biodegradable polymer-coated DES implantation. The secondary aim is to determine the predictors and prognostic implications of bleeding.

METHODS

This study is a post hoc analysis of the Multi-Center Registry of EXCEL Biodegradable Polymer Drug Eluting Stents (CREATE) study population. A total of 2,040 patients surviving at 6 months were studied, including 1,639 (80.3%) who had received 6-month DAPT and 401 (19.7%) who had received DAPT greater than 6 months. Bleeding events were defined according to the bleeding academic research consortium (BARC) definitions as described previously and were classified as major/minor (BARC 2-5) and minimal (BARC 1). A left censored method with a landmark at 6 months was used to determine the incidence, predictors, and impact of bleeding on clinical prognosis between 6 and 12 months.

RESULTS

At 1-year follow-up, patients who received prolonged DAPT longer than 6 months had a significantly higher incidence of overall (3.0% vs. 5.5%, P = 0.021) and major/minor bleeding (1.1% vs. 2.5%, P = 0.050) compared to the patients who received 6-month DAPT. Multivariate analysis showed that being elderly (OR = 1.882, 95% CI: 1.109-3.193, P = 0.019), having diabetes (OR = 1.735, 95% CI: 1.020-2.952, P = 0.042), having a history of coronary artery disease (OR = 2.163, 95% CI: 1.097-4.266, P = 0.026), and duration of DAPT longer than 6 months (OR = 1.814, 95% CI: 1.064-3.091, P = 0.029) were independent predictors of bleeding. Patients with bleeding events had a significantly higher incidence of cardiac death, myocardial infarction, target lesion revascularization, and stent thrombosis.

CONCLUSIONS

Prolonged DAPT (greater than 6 months) after biodegradable polymer-coated DES increases the risk of bleeding, and is associated with adverse cardiac events at 1-year follow-up. (J Interven Cardiol 2014;27:119-126).

Prevalence, predictors, and long-term prognosis of premature discontinuation of oral antiplatelet therapy after drug eluting stent implantation

To date, limited information is available on the long-term discontinuation rates of antiplatelet therapy after drug-eluting stent implantation. The aim of the present study was to determine the prevalence and predictors of premature discontinuation of oral antiplatelet therapy after drug-eluting stent implantation and to evaluate its effects on long-term prognosis. We studied 1,358 consecutive patients successfully treated with drug-eluting stents and discharged with dual oral antiplatelet therapy. Aspirin was to be maintained lifelong, and clopidogrel was prescribed for 12 months. The patients were followed for 36 months. The prevalence and predictors of aspirin and clopidogrel discontinuation were assessed. Major adverse cardiac events, defined as death, myocardial infarction, destabilizing symptoms leading to hospitalization, and nonfatal stroke, were recorded. Definite, probable, and possible stent thrombosis (ST) and major and minor bleeding were also determined. Of the 1,358 patients, 8.8% had discontinued one or both antiplatelet agents within the first 12 months ("early" discontinuation) and 4.8% had discontinued aspirin after 1 year ("late" discontinuation). Early discontinuation was predicted by in-hospital major bleeding, the use of oral anticoagulants at discharge, and the lack of a statin prescription. Previous stroke was the only independent predictor of late discontinuation. Patients with early discontinuation experienced a greater incidence of major adverse cardiac events (28.6% vs 13.7%, p <0.001) and ST (7.6% vs 3.4%, p = 0.038). All-cause mortality (13.4% vs 4.7%, p <0.001) and cardiovascular death (5% vs 1.2%, p = 0.007) were significantly more frequent among patients with early discontinuation. In patients with late discontinuation, a nonstatistically significant increase was seen in major adverse cardiac events (20% vs 13.3%, p = 0.128) and ST (6.2% vs 3.2%, p = 0.275). In conclusion, premature discontinuation of antiplatelet therapy is relatively common, especially within the first year, and strongly associated with increased cardiovascular events, including ST and death.

Late angiographic stent thrombosis: the LAST straw for drug-eluting stents?

The long-term patency advantage of drug-eluting stents represents a quantum leap in the percutaneous treatment of ischemic heart disease. Although initial landmark trials demonstrated equivalent safety to bare-metal stents, subsequent follow-up analyses have suggested a slight late thrombotic risk. This widely publicized issue poses major public health implications for the medical and lay communities. However, available data indicate that this late risk is counterbalanced by the dramatic drug-eluting stent reduction in target lesion revascularizations, resulting in equivalent overall major adverse cardiovascular event rates than that of the bare-metal stents The recent Food and Drug Administration's guidelines regarding these devices are delineated in detail. Specifically, compliance with dual antiplatelet therapy (minimum 1 year) is of paramount consideration in patient selection for drug-eluting stents. Moreover, when deployed for "on-label" indications, they provide significant restenosis advantage, with a slight late thrombotic risk but without overall increase in death or infarction.

Safety and efficacy of the drug-eluting stent: a double-edged sword?

Like the introduction of bare metal stents (BMS), that of drug-eluting stents (DES) represented a quantum leap in the interventional cardiology community's ongoing efforts to conquer restenosis. However, recent concerns over late thrombosis (LT) have tempered the initial enthusiasm. Nonetheless, when compared with BMS, the slightly higher DES-LT is counterbalanced by the device's markedly lower incidence of restenosis, resulting in net equivalent rates of death, myocardial infarction, and overall major adverse cardiovascular events. This article summarizes for the noncardiology practitioner the benefits and risks of DES, as well as essentials of postprocedural care of the DES patient. We discuss the pathophysiology of stent thrombosis, pivotal DES trials, and adjunct antiplatelet pharmacology. In December 2006, the Food and Drug Administration convened an expert panel to review these devices. Their recommendations, as well as the joint statement from the American College of Cardiology/American Heart Association/Society of Cardiovascular Angiography and Interventions, are outlined.

In vitro studies of platelet adhesion, activation, and protein adsorption on curcumin-eluting biodegradable stent materials

A major complication of coronary stenting is in-stent restenosis (ISR) due to thrombus formation. We hypothesized that locally released curcumin from coronary stent surface would inhibit ISR due to thrombus formation because of antithrombosis of curcumin. In the present work, curcumin-eluting polylactic acid-co-glycolic acid (PLGA) films were fabricated and their properties in vitro were investigated. The in vitro platelet adhesion and activation, as well as protein adsorption on curcumin-loading PLGA films were investigated to evaluate the blood compatibility of curcumin-eluting films. The structure of curcumin-eluting PLGA film and control was examined by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicating that the peaks of curcumin did not shift in curcumin-eluting films. The results of contact angle and surface free energy indicated that loading curcumin in PLGA would make PLGA become more hydrophilic, which contributed to the increase of polar fraction of surface free energy. With the increase of curcumin in films, platelets adhering to the curcumin-eluting films decreased significantly. The number of activation platelets decreased after incorporating curcumin in PLGA films. Loading curcumin in PLGA film can markedly reduce the fibrinogen adsorption. All results indicated that incorporating curcumin in PLGA film can improve the blood compatibility of PLGA films. It can be used to fabricate drug-eluting stent to prevent thrombosis formation.

Biocompatibility of tetramethylpyrazine-eluting stents in normal porcine coronary arteries

OBJECTIVE

Drug-eluting stents have been used to markedly decrease in-stent restenosis in 6 months, but they are noticed due to the late thrombogenicity. The purpose of the present study was to evaluate the biocompatibility of Tetramethylpyrazine-eluting stents by investigating the intimal response and thrombogenicity in normal porcine coronary arteries by quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and histomorphometry.

METHODS

Bare metal stents (BMS) were uniformly spray-coated with Tetramethylpyrazine (TMP 200 microg) and prepared for TMP-eluting stents (TES). Fourteen coronary arteries in 14 pigs underwent stent implantation. Seven TES were implanted in 7 pigs and 7 BMS in other 7 pigs. The stents were deployed with a stent-to-artery ratio of 1.1-1.2/1.0 in order to induce vascular wall injury. QCA and IVUS were performed before and immediately after the implantations and at 28 days (end time point). The analysis on blood cell count, biochemical parameters, status of behavior of pigs were evaluated before the implantation and at the time of 1 and 28 days. Stented-coronary arteries, stented-coronary arteries related ventricular wall, lung, liver and kidney were harvested after euthanasia of animals at the endpoint. Histopathology and histomorphometry had been done to assess the local toxicity of TES to these organs.

RESULTS

All the stents were successfully implanted, however, 4 pigs died of cardiac tamponade or anesthesia. No bone marrow depression and hemolysis was seen. No damage to the function and metabolism of liver and kidney was discovered. No thrombosis was found in control and test groups. Few inflammatory cells were found in the stented-coronary artery walls at each endpoint in both groups. No damage to stented-coronary arteries related ventricular wall, lung, liver and kidney was detected due to TES implantation. Compared with the control group, the neointimal area was significantly reduced in the TES group (60.2+/-23.5% vs 10.0+/-2.1%, P=0.01) by IVUS analysis, but the lumen area in the TES group was increased (4.34+/-0. 93 mm(2) vs 1.29+/-1.02 mm(2), P=0.011), the neointimal area was reduced markedly (1.51+/-0.45 mm(2) vs 4.60+/-1.39 mm(2), P=0.004).

CONCLUSIONS

The biocompatibility of TES in porcine model at 28 days seems to be good and acceptable. Biocompatibility can be evaluated by IVUS and histopathology in a porcine restenosis model.

Adhesion Evaluation of Titanium Oxides Films on 316L Stainless Steel Substrate

Titanium oxides films were deposited on tensile sample and vascular stents made of 316L stainless steel by unbalanced magnetron sputtering. The effects of structures, deposition temperature, Ti interlayer and thickness on the adhesion of titanium oxide films were investigated by tensile tests. The results revealed that the structure of the Ti-O films affect their adhesion dramatically. TiO film is brittle and fragile, lacking ability of deformation. Therefore its adhesion was worse than that of TiO2 film. The higher substrate temperature was helpful to improve adhesion of film, the adhesion of the TiO film deposited at 673K was better than those of the TiO films deposited at 323K and 473K. The adhesion of the TiO film with Ti interlayer was better than the one without interlayer. The introduction of Ti interlayer was beneficial to adhesion of film. The adhesion of thinner TiO2 film was better than that of thicker one. TiO2 film deposited on stents had good adhesion. After expansion, the film didn’t crack and peel off. TiO2 film has potential application on the vascular stents for improving its blood compatibility.

Incidence and predictors of drug-eluting stent thrombosis during and after discontinuation of thienopyridine treatment

BACKGROUND

The need for prolonged aspirin and thienopyridine therapy and the risk of stent thrombosis (ST) remain as drawbacks associated with drug-eluting stents.

METHODS AND RESULTS

A prospective observational cohort study was conducted between June 2002 and January 2004 on 3021 patients consecutively and successfully treated in 5389 lesions with drug-eluting stents. Detailed patient information was collected on antiplatelet therapy. We analyzed the incidence of ST throughout the 18-month follow-up period and its relationship with thienopyridine therapy. ST occurred in 58 patients (1.9%) at 18 months. Forty-two patients (1.4%) experienced the event within 6 months of stent implantation. Acute myocardial infarction (fatal or nonfatal) occurred in 46 patients (79%) and death in 23 patients (39%) with ST. The median interval from discontinuation of thienopyridine therapy to ST was 13.5 days (interquartile range 5.2 to 25.7 days) for the first 6 months and 90 days (interquartile range 30 to 365 days) between 6 and 18 months. On multivariable analysis, the strongest predictor for ST within 6 months of stenting was discontinuation of thienopyridine therapy (hazard ratio, 13.74; 95% CI, 4.04 to 46.68; P<0.001). Thienopyridine discontinuation after 6 months did not predict the occurrence of ST (hazard ratio, 0.94; 95% CI, 0.30 to 2.98; P=0.92).

CONCLUSIONS

Discontinuation of thienopyridine therapy was the major determinant of ST within the first 6 months, but insufficient information is available to determine whether there is benefit in continuing a thienopyridine beyond 6 months.

Improved blood compatibility of rapamycin-eluting stent by incorporating curcumin

This paper dealt with improving the blood compatibility of the rapamycin-eluting stent by incorporating curcumin. The rapamycin- and rapamycin/curcumin-loaded PLGA (poly(d,l-lactic acid-co-glycolic acid)) coatings were fabricated onto the surface of the stainless steel stents using an ultrasonic atomization spray method. The structure of the coating films was characterized by Fourier transform infrared spectroscopy (FTIR). The optical microscopy and scanning electron microscopy (SEM) images of the drug-eluting stents indicated that the surface of all drug-eluting stents was very smooth and uniform, and there were not webbings and "bridges" between struts. There were not any cracks and delaminations on stent surface after expanded by the angioplasty balloon. The in vitro platelet adhesion and activation were investigated by static platelet adhesion test and GMP140 (P-selection), respectively. The clotting time was examined by activated partially prothromplastin time (APTT) test. The fibrinogen adsorption on the drug-loaded PLGA films was evaluated by enzyme-linked immunosorbent assay (ELISA). All obtained data showed that incorporating curcumin in rapamycin-loaded PLGA coating can significantly decrease platelet adhesion and activation, prolong APTT clotting time as well as decrease the fibrinogen adsorption. All results indicated that incorporating curcumin in rapamycin-eluting coating obviously improve the blood compatibility of rapamycin-eluting stents. It was suggested that it may be possible to develop a drug-eluting stent which had the characteristics of not only good anti-proliferation but also improved anticoagulation.

Is late stent thrombosis in drug-eluting stents a real clinical issue? A single-center experience and review of the literature

BACKGROUND

Randomized studies have not found an increased rate of late stent thrombosis (LAST) in drug-eluting stents (DES) compared with bare metal stents (BMS) but those studies were statistically not powered to show such a difference. At the same time there is an increasing number of reports of LAST in DES patients in the current literature.

PATIENTS AND METHODS

We tried to describe the incidence of LAST in an unselected DES and BMS patient population. All patients who underwent stenting in our hospital between October 2003 and March 2006 were included in the study (n=1377). A total of 424 (30.1%) patients were treated with only BMS stents, 520 (37.8%) with paclitaxel-eluting stents (PES), 384 (27.9%) with sirolimus-eluting stents (SES) and 49 (3.6%) with BMS and DES. Long-term follow-up of all patients was used to determine the incidence of LAST as defined by angiographically proven stent thrombosis associated with acute symptoms more than 30 days after stent implantation. Followup was between 1 month and 2 years 7 months (mean 12 months). Patients treated with DES were younger (66+/-11 years) than BMS patients (72+/-10 years; p<0.001) and more often had diabetes (24.2% vs 17.4%; p < 0.001). A previous PCI had been performed in 27.1% of DES patients vs 13.9% of BMS patients (p < 0.001).

RESULTS

There were 9 cases of LAST: 2 with SES (at 6 and 11 months after implantation), 6 with PES (at 6, 9 (2x), 10, 16 and 26 months), and one with BMS (at 22 months). All patients with LAST presented with STEMI and without an angina history that suggested restenosis. Two cases were related to complete cessation of antiplatelet therapy, one because of patient non-compliance (SES), one after aspirin was stopped for orthopedic surgery (BMS). Two cases occurred within 1 month of cessation of clopidogrel therapy and while these patients were on aspirin therapy. Five cases occurred on aspirin monotherapy 2, 3, 4, 10 and 20 months, respectively after planned cessation of clopidogrel. None of the cases occurred under dual antiplatelet therapy. All patients underwent primary PCI; none died.

CONCLUSION

Angiographically proven LAST occurred in our unselected patient population with an incidence of 0.84% in patients treated with DES and 0.21% in BMS patients within a mean follow-up of 12 months (p = 0.36). LAST may indeed occur in clinically stable patients while on aspirin monotherapy. Since LAST led in all patients to STEMI it seems to be a serious clinical issue that prompts further investigation and discussion of length of dual platelet therapy.

Regulatory issues facing the development of drug-eluting stents: a US FDA perspective

Coronary drug-eluting stents (DES) are a breakthrough technology that has changed the standard of care for many patients undergoing percutaneous intervention for coronary artery disease. Initial trials of two DES demonstrated significant clinical benefit with respect to the need for reintervention when compared with bare metal stents. However, more recent studies of DES involve in-patients with more complex disease, such as bifurcation lesions, chronic total occlusions and multiple-vessel disease. Additionally, DES are now being evaluated in patients previously only considered for surgical intervention. Assessment of DES in these complicated patient populations can lead to challenges in trial design, but the US FDA is willing to consider alternative clinical trial designs and statistical analysis plans. Other complex issues associated with DES include duration of clinical trials to determine safety, and the appropriate dose and duration of concomitant antiplatelet therapy. Finally, the FDA acknowledges that DES are complex products to produce and we believe that through interaction with the FDA during development, difficulties with test methodologies, animal studies and clinical trial designs can be addressed. The future of DES likely involves new stent and carrier materials, including biodegradable materials and new drugs and biologicals. The FDA anticipates continued collaboration with physicians, manufacturers, academic institutions and professional societies.