Intravascular Ultrasound Results From the ENDEAVOR IV Trial

Solid implantable devices for sustained drug delivery

Implantable drug delivery systems (IDDS) are an attractive alternative to conventional drug administration routes. Oral and injectable drug administration are the most common routes for drug delivery providing peaks of drug concentrations in blood after administration followed by concentration decay after a few hours. Therefore, constant drug administration is required to keep drug levels within the therapeutic window of the drug. Moreover, oral drug delivery presents alternative challenges due to drug degradation within the gastrointestinal tract or first pass metabolism. IDDS can be used to provide sustained drug delivery for prolonged periods of time. The use of this type of systems is especially interesting for the treatment of chronic conditions where patient adherence to conventional treatments can be challenging. These systems are normally used for systemic drug delivery. However, IDDS can be used for localised administration to maximise the amount of drug delivered within the active site while reducing systemic exposure. This review will cover current applications of IDDS focusing on the materials used to prepare this type of systems and the main therapeutic areas of application.

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK)/Fibroblast Growth Factor-Inducible 14 (Fn14) Axis in Cardiovascular Diseases: Progress and Challenges

Cardiovascular diseases (CVD) are the leading cause of mortality in Western countries. CVD include several pathologies, such as coronary artery disease, stroke, peripheral artery disease, and aortic aneurysm, among others. All of them are characterized by a pathological vascular remodeling in which inflammation plays a key role. Interaction between different members of the tumor necrosis factor superfamily and their cognate receptors induce several biological actions that may participate in CVD. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its functional receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed during pathological cardiovascular remodeling. The TWEAK/Fn14 axis controls a variety of cellular functions, such as proliferation, differentiation, and apoptosis, and has several biological functions, such as inflammation and fibrosis that are linked to CVD. It has been demonstrated that persistent TWEAK/Fn14 activation is involved in both vessel and heart remodeling associated with acute and chronic CVD. In this review, we summarized the role of the TWEAK/Fn14 axis during pathological cardiovascular remodeling, highlighting the cellular components and the signaling pathways that are involved in these processes.

A major role of TWEAK/Fn14 axis as a therapeutic target for post-angioplasty restenosis

Background

Tumor necrosis factor-like weak inducer of apoptosis (Tnfsf12; TWEAK) and its receptor Fibroblast growth factor-inducible 14 (Tnfrsf12a; Fn14) participate in the inflammatory response associated with vascular remodeling. However, the functional effect of TWEAK on vascular smooth muscle cells (VSMCs) is not completely elucidated.

Methods

Next generation sequencing-based methods were performed to identify genes and pathways regulated by TWEAK in VSMCs. Flow-citometry, wound-healing scratch experiments and transwell migration assays were used to analyze VSMCs proliferation and migration. Mouse wire injury model was done to evaluate the role of TWEAK/Fn14 during neointimal hyperplasia.

Findings

TWEAK up-regulated 1611 and down-regulated 1091 genes in VSMCs. Using a gene-set enrichment method, we found a functional module involved in cell proliferation defined as the minimal network connecting top TWEAK up-regulated genes. In vitro experiments in wild-type or Tnfrsf12a deficient VSMCs demonstrated that TWEAK increased cell proliferation, VSMCs motility and migration. Mechanistically, TWEAK increased cyclins (cyclinD1), cyclin-dependent kinases (CDK4, CDK6) and decreased cyclin-dependent kinase inhibitors (p15^lNK4B) mRNA and protein expression. Downregulation of p15^INK4B induced by TWEAK was mediated by mitogen-activated protein kinase ERK and Akt activation.

Tnfrsf12a or Tnfsf12 genetic depletion and pharmacological intervention with TWEAK blocking antibody reduced neointimal formation, decreasing cell proliferation, cyclin D1 and CDK4/6 expression, and increasing p15^INK4B expression compared with wild type or IgG-treated mice in wire-injured femoral arteries. Finally, immunohistochemistry in human coronary arteries with stenosis or in-stent restenosis revealed high levels of Fn14, TWEAK and PCNA in VSMCs enriched areas of the neointima as compared with healthy coronary arteries.

Interpretation

Our data define a major role of TWEAK/Fn14 in the control of VSMCs proliferation and migration during neointimal hyperplasia after wire injury in mice, and identify TWEAK/Fn14 as a potential target for treating in-stent restenosis.

Fund

ISCiii-FEDER, CIBERCV and CIBERDEM.

Histopathological comparison of biodegradable polymer and permanent polymer based sirolimus eluting stents in a porcine model of coronary stent implantation

Biodegradable stent coatings were recently introduced as a potential solution to overcome sustained inflammatory responses observed with permanent polymer-based drug-eluting stents. In a preliminary study, selected biodegradable or permanent polymer-based sirolimus-eluting stent (SES) formulations were screened for effectiveness in comparison to bare metal stents (BMS) at 28 days. Subsequently, the most favourable SES formulation was compared to commercially available SES (CypherTM) at 28,90 and 180 days to investigate the histopathologic response as well as tissue, blood and organ pharmacokinetics. Overlapping SES implantation was conducted to evaluate vascular healing at 28 days in this particular setting. SES with biodegradable poly (L-lactide) polymer (PLLA) or poly(lactide-co-glycolide) showed the most favourable outcome with regards to reductions in neointimal area in comparison to BMS at 28 days. The PLLA SES showed a similar reduction in neointimal area compared to CypherTM at 28 days, with significant greater reductions at 90 and 180 days (1.7 ± 0.7 mm2 vs. 3.1 ± 1.5 mm2, p=0.03 and 1.8 ± 1.2 mm2 vs. 3.0 ± 1.5 mm2, p=0.01, respectively). Sirolimus vascular tissue concentrations were detectable up to 90 days following implantation. Overlapping stented segments showed favourable histopathologic results with respect to fibrin deposition and endothelialisation at 28 days. In conclusion, the use of PLLA as drugeluting matrix resulted in mild inflammatory responses in the presence of effective sirolimus tissue concentrations. The greater efficacy observed at long-term follow-up in PLLA SES compared to CypherTM may be a multifactorial result of stent design, polymer biocompatibility and improved release kinetics.

Relative dose and vascular response after drug-eluting stent implantation: A dosimetric 3D-intravascular ultrasound study

BACKGROUND

In drug-eluting stents (DESs), the theoretical drug dose exposed to the vessel wall per stent surface area may vary due to the fixed loading dose and differences in the stent surface area once expanded in varying vessel sizes. The aim of this study was to evaluate the potential effects of different dose intensities, as estimated by 3D-IVUS dosimetry, on vascular response after DES implantation.

METHODS

Follow-up (6-9 months) 3D-IVUS was performed in 840 coronary lesions treated with a single DES of the following types: sirolimus (SES, n=148), paclitaxel (PES, n=162), Endeavor zotarolimus (E-ZES, n=233), Resolute zotarolimus (R-ZES, n=147), and everolimus (EES, n=150). Volume index (volume/length, mm(3)/mm) was obtained for vessel, lumen, plaque, stent, and neointima. In each lesion, exposed dose intensity was calculated as known loading dose divided by measured luminal surface area of the stented segment. Lesions were divided into tertiles based on the exposed dose intensity: high, medium, and low dose groups.

RESULTS

The exposed dose intensity ranged 0.74-1.76 μg/mm(2) for SES, 0.41-1.18 μg/mm(2) for PES, 0.71-1.57 μg/mm(2) for E-ZES, 0.72-1.63 μg/mm(2) for R-ZES, and 0.40-0.99 μg/mm(2) for EES. All types of DES showed no significant difference in neointimal hyperplasia among the 3 groups, except that E-ZES showed significantly less neointimal hyperplasia in the high dose group.

CONCLUSIONS

Detailed 3D-IVUS revealed significant lesion-to-lesion variability in dose intensity exposed to the vessel wall following DES implantation. However, the major types of DES appear to yield equally effective neointimal suppression, despite the varying dose intensity, except for E-ZES.

Polymers for Cardiovascular Stent Coatings

Polymers have found widespread applications in cardiology, in particular in coronary vascular intervention as stent platforms (scaffolds) and coating matrices for drug-eluting stents. Apart from permanent polymers, current research is focussing on biodegradable polymers. Since they degrade once their function is fulfilled, their use might contribute to the reduction of adverse events like in-stent restenosis, late stent-thrombosis, and hypersensitivity reactions. After reviewing current literature concerning polymers used for cardiovascular applications, this review deals with parameters of tissue and blood cell functions which should be considered to evaluate biocompatibility of stent polymers in order to enhance physiological appropriate properties. The properties of the substrate on which vascular cells are placed can have a large impact on cell morphology, differentiation, motility, and fate. Finally, methods to assess these parameters under physiological conditions will be summarized.

Scaffold and edge vascular response following implantation of everolimus-eluting bioresorbable vascular scaffold: a 3-year serial optical coherence tomography study

OBJECTIVES

This study sought to investigate the in-scaffold vascular response (SVR) and edge vascular response (EVR) after implantation of an everolimus-eluting bioresorbable scaffold (BRS) using serial optical coherence tomography (OCT) imaging.

BACKGROUND

Although studies using intravascular ultrasound have evaluated the EVR in metal stents and BRSs, there is a lack of OCT-based SVR and EVR assessment after BRS implantation.

METHODS

In the ABSORB Cohort B (ABSORB Clinical Investigation, Cohort B) study, 23 patients (23 lesions) in Cohort B1 and 17 patients (18 lesions) in Cohort B2 underwent truly serial OCT examinations at 3 different time points (Cohort B1: post-procedure, 6 months, and 2 years; B2: post-procedure, 1 year, and 3 years) after implantation of an 18-mm scaffold. A frame-by-frame OCT analysis was performed at the 5-mm proximal, 5-mm distal edge, and 2-mm in-scaffold margins, whereas the middle 14-mm in-scaffold segment was analyzed at 1-mm intervals.

RESULTS

The in-scaffold mean luminal area significantly decreased from baseline to 6 months or 1 year (7.22 ± 1.24 mm(2) vs. 6.05 ± 1.38 mm(2) and 7.64 ± 1.19 mm(2) vs. 5.72 ± 0.89 mm(2), respectively; both p < 0.01), but remained unchanged from then onward. In Cohort B1, a significant increase in mean luminal area of the distal edge was observed (5.42 ± 1.81 mm(2) vs. 5.58 ± 1.53 mm(2); p < 0.01), whereas the mean luminal area of the proximal edge remained unchanged at 6 months. In Cohort B2, the mean luminal areas of the proximal and distal edges were significantly smaller than post-procedure measurements at 3 years. The mean luminal area loss at both edges was significantly less than the mean luminal area loss of the in-scaffold segment at both 6-month and 2-year follow-up in Cohort B1 or at 1 year and 3 years in Cohort B2.

CONCLUSIONS

This OCT-based serial EVR and SVR evaluation of the Absorb Bioresorbable Vascular Scaffold (Abbott Vascular, Santa Clara, California) showed less luminal loss at the edges than luminal loss within the scaffold. The luminal reduction of both edges is not a nosologic entity, but an EVR in continuity with the SVR, extending from the in-scaffold margin to both edges. (ABSORB Clinical Investigation, Cohort B [ABSORB B]; NCT00856856).

Meta-analysis of randomized clinical trials comparing short-term versus long-term dual antiplatelet therapy following drug-eluting stents

Current guidelines recommend 12 months of dual antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation in the absence of increased bleeding risk. Studies have suggested that early discontinuation of DAPT can result in an increased risk of stent thrombosis. However, given the potential for major bleeding, the optimal duration of DAPT after DES implantation remains uncertain. We searched PubMed, EMBASE, Scopus, and ClinicalTrials.gov databases from inception until October 2013 for randomized controlled trials that compared shorter versus longer DAPT duration after DES implantation. Four randomized controlled trials were included. A total of 4,081 patients received DAPT for 3 to 6 months, and 4,076 patients were treated with DAPT for 12 to 24 months. Oral DAPT consisted of aspirin and clopidogrel. There was no significant difference in the rate of the composite outcome of cardiac death or myocardial infarction between the short (3.3%) and prolonged (3.0%) DAPT groups (odds ratio 1.11, 95% confidence interval 0.87 to 1.43, p=0.41). A landmark analysis performed at the time of discontinuation of DAPT in the short DAPT group demonstrated a nonsignificant higher rate of stent thrombosis in patients treated with a short course of DAPT (0.35% vs 0.20%, p=0.22). Major bleeding was significantly higher in the group of patients treated with prolonged DAPT (0.29% vs 0.71%, p=0.01). In conclusion, prolonged DAPT compared with short-term treatment is associated with increased major bleeding but is not associated with a decrease in the composite rates of death or myocardial infarction.

Comparison of vascular response to the everolimus-eluting stent versus the paclitaxel-eluting stent: intravascular ultrasound results from the SPIRIT III trial

AIMS

The purpose of this study was to investigate the vascular response of the everolimus-eluting stent (EES) compared with the paclitaxel-eluting stent (PES) using serial intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the SPIRIT III trial, a multicentre, 2:1 randomised, controlled study comparing EES and PES in de novo native coronary artery lesions. IVUS images were eligible for volumetric analysis at eight-month follow-up in 158 lesions (EES: 113, PES: 45). At eight months, EES had a smaller neointimal volume index (VI: mm3/mm) (EES: 0.4±0.4 vs. PES: 0.8±0.8 mm3/mm, p=0.002) and also a smaller % neointimal obstruction (EES: 7.1±6.7% vs. PES: 11.1±10.5%, p=0.005) compared with PES. While there was no significant change in vessel VI with EES, there was a significant increase in vessel VI in PES during eight-month follow-up (EES: 0.1±1.2 vs. PES: 1.2±0.8 mm3/mm, p=0.001). There were no statistical differences in the frequency of edge dissection or incomplete stent apposition between the two groups.

CONCLUSIONS

Detailed IVUS analysis confirmed significantly less neointimal hyperplasia with EES compared with PES. While there was no increase in vessel volume with EES during the eight-month follow-up period, vessel enlargement was seen at the stented segment in PES.

Optimized duration of clopidogrel therapy following treatment with the Endeavor zotarolimus-eluting stent in real-world clinical practice (OPTIMIZE) trial: rationale and design of a large-scale, randomized, multicenter study

BACKGROUND

Current recommendations for antithrombotic therapy after drug-eluting stent (DES) implantation include prolonged dual antiplatelet therapy (DAPT) with aspirin and clopidogrel ≥12 months. However, the impact of such a regimen for all patients receiving any DES system remains unclear based on scientific evidence available to date. Also, several other shortcomings have been identified with prolonged DAPT, including bleeding complications, compliance, and cost. The second-generation Endeavor zotarolimus-eluting stent (E-ZES) has demonstrated efficacy and safety, despite short duration DAPT (3 months) in the majority of studies. Still, the safety and clinical impact of short-term DAPT with E-ZES in the real world is yet to be determined.

METHODS

The OPTIMIZE trial is a large, prospective, multicenter, randomized (1:1) non-inferiority clinical evaluation of short-term (3 months) vs long-term (12-months) DAPT in patients undergoing E-ZES implantation in daily clinical practice. Overall, 3,120 patients were enrolled at 33 clinical sites in Brazil. The primary composite endpoint is death (any cause), myocardial infarction, cerebral vascular accident, and major bleeding at 12-month clinical follow-up post-index procedure.

CONCLUSIONS

The OPTIMIZE clinical trial will determine the clinical implications of DAPT duration with the second generation E-ZES in real-world patients undergoing percutaneous coronary intervention.

Impact of diabetes mellitus on vessel response in the drug-eluting stent era: pooled volumetric intravascular ultrasound analyses

BACKGROUND

Exaggerated neointimal hyperplasia is considered as the primary mechanism for increased restenosis in patients with diabetes mellitus (DM) treated with bare-metal stent. However, the vessel response in DM and non-DM treated with different drug-eluting stents (DES) has not been systematically evaluated.

METHODS AND RESULTS

We investigated 3D intravascular ultrasound (postprocedure and 6 to 9 months) in 971 patients (267 with DM and 704 without DM) treated with sirolimus- (n=104), paclitaxel- (n=303), zotarolimus- (n=391), or everolimus- (n=173) eluting stents. Volumetric data were standardized by length as volume index (VI). At postprocedure, lumen VI at the stented segment was significantly smaller in DM than in non-DM, whereas vessel VI was similar between the 2 groups. At follow-up, neointimal obstruction and maximum cross-sectional narrowing (neointimal area/stent area) were not significantly different between the 2 groups with no interaction for the DES type. Consequently, lumen VI was smaller in DM than in non-DM at follow-up. In the reference segments, residual plaque burden at postprocedure was significantly greater in DM than in non-DM, although change in lumen VI was similar between the 2 groups. The arterial responses at the reference segments also showed no interaction for the DES type.

CONCLUSIONS

DM and non-DM lesions showed similar vessel response in both in-stent and reference segments regardless of the DES type. In the DES era, the follow-up lumen in DM patients seems to be determined primarily by the smaller lumen at postprocedure rather than exaggerated neointima within the stent or plaque proliferation at the reference segments.

Stent thrombosis: an overview

Stent thrombosis is a challenging problem following percutaneous coronary intervention that can lead to serious clinical consequences, such as death and acute myocardial infarction. Its pathophysiology is not yet completely known, and there are several causes suggested, such as incomplete stent endothelization, presence of polymers and late incomplete stent apposition. One of the main predictors is the early discontinuation of dual antiplatelet therapy. Stent improvements related to their design, with more friendly metallic platforms, thinner biocompatible or biodegradable polymers, absence of polymers, and even stents manufactured with bioabsorbable materials, could make the percutaneous procedure much safer and effective, allowing its application in increasingly complex anatomic and clinical scenarios, with low thrombosis rates.

Sex differences in neointimal hyperplasia following endeavor zotarolimus-eluting stent implantation

Inconsistent results in outcomes have been observed between the genders after drug-eluting stent implantation. The aim of this study was to investigate gender differences in neointimal proliferation for the Endeavor zotarolimus-eluting stent (ZES) and the Driver bare-metal stent (BMS). A total of 476 (n = 391 ZES, n = 85 BMS) patients whose volumetric intravascular ultrasound analyses were available at 8-month follow-up were studied. At 8 months, neointimal obstruction and maximum cross-sectional narrowing (CSN) were significantly lower in women than in men receiving ZES (neointimal obstruction 15.5 ± 9.5% vs 18.2 ± 10.9%, p = 0.025; maximum CSN 30.3 ± 13.2% vs 34.8 ± 15.0%, p = 0.007). Conversely, these parameters tended to be higher in women than in men receiving BMS (neointimal obstruction 36.3 ± 15.9% vs 27.5 ± 17.2%, p = 0.053; maximum CSN 54.3 ± 18.6% vs 45.6 ± 18.3%, p = 0.080). There was a significant interaction between stent type and gender regarding neointimal obstruction (p = 0.001) and maximum CSN (p = 0.003). Multivariate linear regression analysis revealed that female gender was independently associated with lower neointimal obstruction (p = 0.027) and maximum CSN (p = 0.004) for ZES but not for BMS. Compared to BMS, ZES were independently associated with a reduced risk for binary restenosis in both genders (odds ratio for women 0.003, p = 0.001; odds ratio for men 0.191, p <0.001), but the magnitude of this risk reduction with ZES was significantly greater in women than men (p = 0.015). In conclusion, female gender is independently associated with decreased neointimal hyperplasia in patients treated with ZES. The magnitude of risk reduction for binary restenosis with ZES is significantly greater in women than in men.

Regulator of calcineurin 1 mediates pathological vascular wall remodeling

Angiotensin-II–driven calcineurin activation and regulator of calcineurin-1 (Rcan-1) expression is required for pathological vascular remodeling in mice.

Artery wall remodeling, a major feature of diseases such as hypertension, restenosis, atherosclerosis, and aneurysm, involves changes in the tunica media mass that reduce or increase the vessel lumen. The identification of molecules involved in vessel remodeling could aid the development of improved treatments for these pathologies. Angiotensin II (AngII) is a key effector of aortic wall remodeling that contributes to aneurysm formation and restenosis through incompletely defined signaling pathways. We show that AngII induces vascular smooth muscle cell (VSMC) migration and vessel remodeling in mouse models of restenosis and aneurysm. These effects were prevented by pharmacological inhibition of calcineurin (CN) or lentiviral delivery of CN-inhibitory peptides. Whole-genome analysis revealed >1,500 AngII-regulated genes in VSMCs, with just 11 of them requiring CN activation. Of these, the most sensitive to CN activation was regulator of CN 1 (Rcan1). Rcan1 was strongly activated by AngII in vitro and in vivo and was required for AngII-induced VSMC migration. Remarkably, Rcan1^−/− mice were resistant to AngII-induced aneurysm and restenosis. Our results indicate that aneurysm formation and restenosis share mechanistic elements and identify Rcan1 as a potential therapeutic target for prevention of aneurysm and restenosis progression.

Three-year clinical outcome with the Endeavor™ zotarolimus-eluting stent in primary percutaneous coronary intervention for ST elevation myocardial infarction: the Endeavor™ primary PCI study (E-PPCI)

Primary percutaneous coronary intervention (PPCI) is superior to thrombolysis in STEMI (ST segment elevation myocardial infarction) patients. Data on late stent thrombosis (ST) have raised concerns regarding the use of drug-eluting stents during PPCI. We report the first 3-year clinical evaluation of the zotarolimus-eluting stent (ZES) in patients undergoing PPCI for STEMI, a single-center, prospective cohort study of consecutive patients admitted with STEMI. All underwent PPCI within 12 hours of symptoms; each received one or more ZES in one or more target lesions. All patients received aspirin 300 mg, clopidogrel 600 mg, abciximab, and unfractionated heparin. A total of 102 STEMI patients (76 male, mean 62 years) received 162 ZES (mean 1.6 stents/patient). Median call-to-balloon time was 123 (102-152) minutes. Thirty-day combined major adverse cardiovascular event (MACE) rate was 3.9% (n = 4). Subacute ST occurred in 2 patients (1.96%). Combined MACE rates at 12 months and 3 years were 7.8% (n = 8) and 13.7% (n = 14). Late ST occurred in 1 patient (1%) with no occurrence of very late ST. This is the first 3-year report of the use of the ZES in an unselected, consecutive PPCI population. Overall 3-year incidence of MACE and target lesion revascularization (5.9%) was low, and was comparable to that seen with sirolimus- and paclitaxel-eluting stents in randomized controlled trials. At 3 years there was no occurrence of very late ST.

Optical coherence tomographic comparison of neointimal coverage between sirolimus- and resolute zotarolimus-eluting stents at 9 months after stent implantation

The Resolute zotarolimus-eluting stent (ZES-R) has a thinner stent strut with biocompatible polymer than first generation drug-eluting stents. However, minimal optical coherence tomography (OCT) data exists about vascular responses after ZES-R implantation. This study investigated OCT findings in ZES-R implantation and compared them to those in sirolimus-eluting stent (SES) implantation. A total of 123 lesions (43 ZES-R and 80 SES) in 111 patients were evaluated with OCT at 9 months after stent implantation. Strut apposition, neointimal hyperplasia (NIH) thickness, and stent coverage on each stent strut were evaluated. Mean NIH thickness was significantly greater in ZES-R-treated lesions than in SES-treated lesions (166 ± 73 μm vs. 96 ± 63 μm, respectively, P < 0.001). The percentage of uncovered strut was significantly lower in ZES-R-treated lesions than in SES-treated lesions (4.4 ± 4.8% vs. 10.3 ± 13.2%, respectively, P = 0.05). The percentage of malapposed struts was also significantly lower in ZES-R-treated than in SES-treated lesions (0.1 ± 0.4% vs. 1.5 ± 4.2%, respectively, P = 0.002). Intracoronary thrombus was less frequently detected in ZES-R-treated lesions (4.7% vs. 30.0%, respectively, P = 0.001). ZES-R showed a lower incidence of uncovered or malapposed stent struts and intracoronary thrombus than SES at 9-month follow-up OCT examination. Compared with SES, ZES-R may elicit more favorable vascular responses at the expense of an increased neointimal proliferation.

Impact of Polymer Formulations on Neointimal Proliferation After Zotarolimus-Eluting Stent With Different Polymers

Background—

Polymer formulation may affect the efficacy of drug-eluting stents. Resolute, Endeavor, and ZoMaxx are zotarolimus-eluting stents with different stent platforms and different polymer coatings and have been tested in clinical trials. The aim of this analysis was to compare the efficacy of zotarolimus-eluting stents with different polymers.

Methods and Results—

Data were obtained from the first-in man trial or first randomized trials of each stent, The Clinical RESpOnse EvaLUation of the MedTronic Endeavor CR ABT-578 Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (RESOLUTE), Randomized Controlled Trial to Evaluate the Safety and Efficacy of the Medtronic AVE ABT-578 Eluting Driver Coronary Stent in De Novo Native Coronary Artery Lesions (ENDEAVOR II), and ZoMaxx I trials. Follow-up intravascular ultrasound analyses (8 to 9 months of follow-up) were possible in 353 patients (Resolute: 88, Endeavor: 98, ZoMaxx: 82, Driver: 85). Volume index (volume/stent length) was obtained for vessel, stent, lumen, peristent plaque, and neointima. Cross-sectional narrowing was defined as neointimal area divided by stent area (%). Neointima-free frame ratio was calculated as the number of frames without intravascular ultrasound–detectable neointima divided by the total number of frames within the stent. At baseline, vessel, lumen, and peristent plaque volume index were not significantly different among the 4 stent groups. At follow-up, percent neointimal obstruction was significantly lower in Resolute compared with Endeavor, ZoMaxx, and Driver (Resolute: 3.7±4.0, Endeavor: 17.5±10.1, ZoMaxx: 14.6±8.1, Driver: 29.4±17.2%; P <0.001). Greater maximum cross-sectional narrowing and higher neointima-free frame ratio, suggesting less neointimal coverage, were observed in Resolute compared with other stent groups. Multiple regression analysis confirmed that the biodurable polymer used in Resolute independently correlated with neointimal suppression among 3 zotarolimus-eluting stents.

Conclusions—

The different polymer formulations significantly affect the relative amount of neointima for zotarolimus-eluting stents.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00248079.

Long-term clinical outcomes with zotarolimus-eluting versus bare-metal coronary stents

OBJECTIVES

This study sought to evaluate the long-term safety of the zotarolimus-eluting stent (ZES) using a pooled analysis of pivotal trials.

BACKGROUND

Drug-eluting stents, compared with bare-metal stents (BMS), have reduced restenosis; however, individual trials of these stents have not had sufficient power to ascertain long-term safety.

METHODS

We combined patient level data from 6 prospective randomized single-arm multicenter trials involving 2,132 patients treated with ZES and 596 patients treated with a BMS control. The median follow-up was 4.1 years, with 5-year follow-up completed in 1,256 patients (97% of those eligible). The recommended minimum duration of dual antiplatelet therapy in these studies was 3 to 6 months regardless of stent type. An independent events committee adjudicated all events. The 2 treatment groups were compared after adjustment for between trial variation and for individual patient clinical and angiographic characteristics by propensity score.

RESULTS

The cumulative incidence of adverse events at 5 years for ZES and BMS were: death: 5.9% versus 7.6% (adjusted hazard ratio: 0.81, p = 0.34), cardiac death: 2.4 versus 3.7% (0.83, p = 0.57), myocardial infarction: 3.4 versus 4.8% (0.77, p = 0.37), target lesion revascularization: 7.0% vs. 16.5% (0.42, p < 0.001), stent thrombosis (definite or probable): 0.8 versus 1.7% (0.50, p = 0.21). After adjustment for variation in study and patient characteristics, there were no significant differences in stent thrombosis or the clinical safety event rates at 5 years between ZES and BMS.

CONCLUSIONS

Over 5 years, there was no increased risk of death, myocardial infarction, or stent thrombosis, and there was a benefit of prevention of repeat revascularization procedures in ZES compared with BMS.

Strut coverage and vessel wall response to zotarolimus-eluting and bare-metal stents implanted in patients with ST-segment elevation myocardial infarction: the OCTAMI (Optical Coherence Tomography in Acute Myocardial Infarction) Study

OBJECTIVES

Using optical coherence tomography, we assessed the proportion of uncovered struts at 6-month follow-up in zotarolimus-eluting stents (ZES), specifically Endeavor (Medtronic CardioVascular, Santa Rosa, California) stents, and identical bare-metal stents (BMS) implanted in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Sirolimus- and paclitaxel-eluting stents implanted in STEMI have been associated with delayed healing and incomplete strut coverage. ZES are associated with a more complete and uniform strut coverage in stable patients, but whether this holds true also after STEMI is unknown.

METHODS

Forty-four patients with STEMI who underwent primary PCI were randomized to ZES or BMS (3:1 randomization). Angiographic, intravascular ultrasound, and optical coherence tomography follow-up was conducted at 6 months and clinical follow-up at 1 year. All images were analyzed by an independent core laboratory that was blind to stent assignments.

RESULTS

There were no differences between ZES and BMS in percentage of uncovered struts (median: 0.00% [interquartile range (IQR): 0.00% to 1.78%] vs. 1.98% [IQR: 0.21% to 7.33%], p = 0.13), maximum length of uncovered segments (0.00 [IQR: 0.00 to 1.19] mm vs. 1.38 [IQR: 0.65 to 3.30] mm, p = 0.10), percentage of malapposed struts (0.00% [IQR: 0.00% to 0.23%] vs. 0.15% [IQR: 0.00% to 5.81%], p = 0.16), and maximum length of malapposed segments (0.00 [IQR: 0.00 to 0.67] mm vs. 0.33 [IQR: 0.00 to 2.55] mm, p = 0.20). Neointimal response was similar between ZES and BMS (332 [IQR: 240 to 429] microm vs. 186 [IQR: 136 to 348] microm, p = 0.99) and evenly distributed. No late acquired malapposition was observed in both groups. There were no deaths, myocardial infarction, or stent thromboses at 1 year.

CONCLUSIONS

This optical coherence tomography study found no difference in strut coverage and similar vessel response to ZES, when compared with identical BMS, implanted during primary percutaneous coronary intervention in STEMI patients. (Six-Month Coverage and Vessel Wall Response of the Zotarolimus Drug-Eluting Stent Implanted in AMI Assessed by Optical Coherence Tomography [OCTAMI]; NCT00704561).

Comparison of vascular response to zotarolimus-eluting stent vs paclitaxel-eluting stent implantation: pooled IVUS results from the ZoMaxx I and II trials

BACKGROUND

The ZoMaxx I and II trials were randomized controlled studies of the zotarolimus-eluting, phosphorylcholine-coated, TriMaxx stent for the treatment of de novo coronary lesions. The aim of this study was to compare the vessel response between zotarolimus- (ZES) and paclitaxel-eluting stents (PES) using intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the ZoMaxx I and II trials, in which a standard IVUS parameter was available in 263 cases (baseline and 9-months follow up). Neointima-free frame ratio was calculated as the number of frames without IVUS-detectable neointima divided by the total number of frames within the stent. While an increase in vessel and plaque was observed in PES from baseline to follow up, there was no significant change in ZES. At follow up, % neointimal obstruction was significantly higher (15.4 ± 8.8% vs 11.3 ± 9.7%), and minimum lumen area at follow up was significantly smaller in ZES compared to PES. However, the incidence of IVUS-defined restenosis (maximum cross-sectional narrowing >60%) was similar in the 2 groups (3.2% vs 6.7%). Neointima-free frame ratio was significantly lower in ZES. There were 5 cases of late incomplete stent apposition in PES and none in ZES.

CONCLUSIONS

These IVUS results demonstrate a similar incidence of severe narrowing between these 2 DES. There was a moderate increase in neointimal hyperplasia that was associated with a greater extent of neointimal coverage in ZES compared with PES.

SPIRIT III JAPAN versus SPIRIT III USA: a comparative intravascular ultrasound analysis of the everolimus-eluting stent

The aim of this study was to evaluate the vascular response after everolimus-eluting stent (EES) implantation in the SPIRIT III Japan Registry (JAPAN) compared to EES implantation in the SPIRIT III United States (USA) trial using serial intravascular ultrasound (IVUS) analysis. Data were obtained from the JAPAN and the randomized EES arm of the USA trial. Serial (postprocedure and 8-month follow-up) IVUS analysis was available in 199 lesions (JAPAN 82, USA 117) of 183 patients (JAPAN 73, USA 110). Although no difference was observed in vessel size in the reference segment between the 2 groups, postprocedure minimum lumen area and stent volume index were significantly greater in the JAPAN arm (minimum lumen area 5.8 +/- 2.2 vs 5.1 +/- 1.5 mm(2), p = 0.03; stent volume index 7.0 +/- 2.4 vs 6.3 +/- 1.7 mm(3)/mm, p = 0.03). Postprocedure incomplete stent apposition (ISA) was less frequently observed in the JAPAN arm (15.9% vs 33.3%, p = 0.006), possibly related to higher maximum balloon pressure and/or more postdilatation without excess tissue prolapse or edge dissection. In the JAPAN arm, percent neointimal obstruction and maximum percent cross-sectional narrowing were significantly lower at 8-month follow-up (percent neointimal obstruction 3.5 +/- 4.2% vs 6.8 +/- 6.4%, p = 0.0004). Late acquired ISA was infrequent in the 2 arms. In conclusion, comparative IVUS analysis between the JAPAN and USA arms showed more optimal stent deployment in the JAPAN arm as evidenced by the lower incidence of postprocedure ISA and larger minimum lumen area after the procedure. Moreover, there was less neointimal hyperplasia in patients with EES implants from the JAPAN arm compared to the USA arm.