Stent Strut Coverage Research Articles

Strut Coverage and Late Malapposition With Paclitaxel-Eluting Stents Compared With Bare Metal Stents in Acute Myocardial Infarction

Background— The safety of drug-eluting stents in ST-segment elevation myocardial infarction (STEMI) continues to be debated. Pathological studies have demonstrated an association between uncovered struts and subsequent stent thrombosis. Optical coherence tomography can detect stent strut coverage in vivo on a micron-scale level. We therefore used optical coherence tomography to examine strut coverage in patients with STEMI treated with paclitaxel-eluting stents (PES) and bare metal stents (BMS). Methods and Results— In the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, patients with STEMI were randomized 3:1 to PES or BMS implantation. In a formal substudy, optical coherence tomography at 13 months was performed in 118 consecutive randomized patients (89 PES, 29 BMS) in whom 188 stents were assessed (146 PES and 42 BMS). A total of 44 139 stent struts were analyzed by an independent core laboratory blinded to stent assignment. The primary prespecified end point, the percentage of uncovered stent struts per lesion at follow-up, was 1.1±2.5% in BMS lesions versus 5.7±7.0% in PES lesions ( P <0.0001). Malapposed struts were observed in 0.1±0.2% of BMS lesions versus 0.9±2.1% of PES lesions ( P =0.0003). Percentage net volume obstruction was 36.0±15.4% with BMS and 19.2±11.3% with PES ( P <0.0001). Conclusions— In patients with STEMI undergoing primary percutaneous coronary intervention, implantation of PES as compared with BMS significantly reduces neointimal hyperplasia but results in higher rates of uncovered and malapposed stent struts as assessed by optical coherence tomography at 13-month follow-up. Further studies are required to determine the clinical significance of these findings. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00433966.

Optical coherence tomography in ST-elevation myocardial infarction treated with novel drug-eluting stent: preprocedural, postimplant and 2-month follow-up findings

The use of drug-eluting stents (DES) allowed the reduction in the need for repeat revascularization. At the culprit site in acute myocardial infarction patients treated with first-generation DES, the interaction between the eluted drug and the underlying necrotic core may generate different patterns of pathologic vessel response and delayed healing. A new generation DES intrepide elutes trapidil. Its modes of action are neither cytotoxic nor cytostatic, and may promote normal re-endothelialization. Due to its high resolution, optical coherence tomography (OCT) allows accurate detection of thrombus deposition and stent strut coverage at follow-up. Intravascular ultrasound (IVUS) has enhanced tissue penetration and provides information on vessel remodeling. Using OCT and IVUS, we evaluated the intravascular morphology of the culprit vessel, the acute and intermediate result of novel DES implanted to treat an ST-segment elevation myocardial infarction.

Vulnerable disease may induce neointimal coverage after silorimus-eluting stent implantation

Neointimal formation can protect against thrombosis after sirolimus-eluting stent (SES) implantation; however, promoters of neointimal formation are unknown. Six-month follow-up angioscopy was performed in 141 consecutive patients with SES implantation. All patients received aspirin (100 mg) and ticlopidine (200 mg) daily until angioscopy. We defined 2 grades of neointimal coverage as follows: insufficient coverage including no or partial neointimal coverage of stent struts, and sufficient coverage. The possible promoters of neointimal formation that were evaluated in this study were the condition of coronary artery disease (stable angina or acute coronary syndrome); angioscopic markers, including visible thrombus and plaque color (white or yellow); serum markers, including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting blood glucose, hemoglobin A(1c), high-sensitive C-reactive protein, and fibrinogen; blood pressure and smoking; intervention markers, including stent size and length and intravascular ultrasound measurements; and medication, including statins, anticoagulants, angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, calcium antagonists, and β-blockers. Univariate analysis revealed that high-sensitive C-reactive protein, plaque color, and the condition of coronary artery disease were significantly correlated with the grade of neointimal coverage. Multivariate analysis using these 3 parameters revealed that only acute coronary syndrome (vulnerable disease) significantly promoted neointimal coverage. Vulnerable disease may promote neointimal coverage after SES implantation.

Coronary optical frequency domain imaging (OFDI) for in vivo evaluation of stent healing: comparison with light and electron microscopy

AimsCoronary late stent thrombosis, a rare but devastating complication, remains an important concern in particular with the increasing use of drug-eluting stents. Notably, pathological studies have indicated that the proportion of uncovered coronary stent struts represents the best morphometric predictor of late stent thrombosis. Intracoronary optical frequency domain imaging (OFDI), a novel second-generation optical coherence tomography (OCT)-derived imaging method, may allow rapid imaging for the detection of coronary stent strut coverage with a markedly higher precision when compared with intravascular ultrasound, due to a microscopic resolution (axial ∼10–20 µm), and at a substantially increased speed of image acquisition when compared with first-generation time-domain OCT. However, a histological validation of coronary OFDI for the evaluation of stent strut coverage in vivo is urgently needed. Hence, the present study was designed to evaluate the capacity of coronary OFDI by electron (SEM) and light microscopy (LM) analysis to detect and evaluate stent strut coverage in a porcine model.Methods and resultsTwenty stents were implanted into 10 pigs and coronary OFDI was performed after 1, 3, 10, 14, and 28 days. Neointimal thickness as detected by OFDI correlated closely with neointimal thickness as measured by LM (r = 0.90, P < 0.01). The comparison of stent strut coverage as detected by OFDI and SEM analysis revealed an excellent agreement (r = 0.96, P < 0.01). In particular, stents completely covered by OFDI analysis were also completely covered by SEM analysis. All incompletely covered stents by OFDI were also incompletely covered by SEM. Analyses of fibrin-covered stent struts suggested that these may rarely be detected as uncovered stent struts by OFDI. Importantly, optical density measurements revealed a significant difference between fibrin- and neointima-covered coronary stent struts [0.395 (0.35–0.43) vs. 0.53 (0.47–0.57); P < 0.001], suggesting that differences in optical density provide information on the type of stent strut coverage. The sensitivity and specificity for detection of fibrin vs. neointimal coverage was evaluated using receiver-operating characteristic analysis.ConclusionThe present study demonstrates that OFDI is a highly promising tool for accurate evaluation of coronary stent strut coverage, as supported by a high agreement between OFDI and light and electron microscopic analysis. Furthermore, our data indicate that optical density measurements can provide additional information with respect to the type of stent strut coverage, i.e. fibrin vs. neointimal coverage. Therefore, coronary OFDI analysis will provide important information on the biocompatibility of coronary stents.

Optical coherence tomography in unprotected left main coronary artery stenting

Delayed or incomplete stent endothelisation and stent malapposition may predispose to DES thrombosis that can be a catastrophic event in the left main coronary artery (LMCA). OCT can accurately identify stent struts and arterial tissue, but is limited by the need of vessel blood clearance and penetration; also no data exist on its use in LMCA. We sought to verify whether optical coherence tomography (OCT) can accurately assess arterial wall response after drug eluting stent (DES) implantation in the LMCA.OCT images were obtained in 15 patients (mean age 70.7 + or - 8.0 years) six months after LMCA DES implantation. Acquisitions were performed without proximal balloon occlusion during isoosmolar contrast injection through a 6 Fr guiding catheter without side holes at a speed of 2-3 mL/sec. Offline image analyses were performed to evaluate assessable stent area (all slices), strut coverage, apposition, and abnormal tissue responses for every three slices (= every 0.45 mm). All OCT images were obtained without periprocedural complications. Overall, 69 + or - 20% of the stent inner area was analysable; this corresponded to 2.7 + or - 0.8 analysable quadrants per slice. Out of 1,281 struts, 1,136 (88.7%) were well apposed and fully covered, 101 (7.8%) were uncovered; and 45 (3.5%) were malapposed although nine of the malapposed struts (20%) were covered by some tissue. In five patients OCT detected abnormal intraluminal tissue, and in two cases this finding was related to uncovered struts.OCT assessment of vascular response after LMCA DES implantation is safe and feasible. Further development of OCT imaging technology will be necessary for complete evaluation of LMCA stents.

Optical Coherence Tomography Assessment of In Vivo Vascular Response After Implantation of Overlapping Bare-Metal and Drug-Eluting Stents

We designed a randomized trial exploiting optical coherence tomography (OCT) to assess coverage and apposition of overlapping bare-metal stents (BMS) and drug-eluting stents (DES) in human coronary arteries. Overlapping DES impair healing in animals. Optical coherence tomography allows accurate in vivo assessment of stent strut coverage and apposition. Seventy-seven patients with long coronary stenoses were randomized to overlapping sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), zotarolimus-eluting stents (ZES), or BMS. The primary goal of the study was to determine the rate of uncovered/malapposed struts in overlap versus nonoverlap segments, according to stent type, at 6-month follow-up with OCT. A total of 53,047 struts were analyzed. The rate of uncovered/malapposed struts was 1.5 +/- 3.4% and 0.6 +/- 2.7% in overlap versus nonoverlap BMS (p = NS), respectively, and 4.3 +/- 11% and 3.6 +/- 8% in overlap versus nonoverlap DES (p = NS), respectively. There were no differences in the rates of uncovered/malapposed struts between overlapping BMS and DES, likely due to low frequency of uncovered/malapposed struts in ZES (0.1 +/- 0.4%), which offset the higher rates observed in SES (6.7 +/- 9.6%) and PES (6.7 +/- 16.5%, p < 0.05). Overlap segments showed greater neointimal volume obstruction versus nonoverlap segments in all DES (p < 0.05 for all DES types). Strut-level neointimal thickness at overlap and nonoverlap segments were lowest in SES (0.16 +/- 0.1 mm and 0.12 +/- 0.1 mm, respectively) compared with PES (0.27 +/- 0.1 mm and 0.20 +/- 0.1 mm, respectively), ZES (0.40 +/- 0.16 mm and 0.33 +/- 0.13 mm, respectively), and BMS (0.55 +/- 0.31 mm and 0.53 +/- 0.25 mm, respectively, p < 0.05). As assessed by OCT the impact of DES on vascular healing was similar at overlapping and nonoverlapping sites. However, strut malapposition, coverage pattern, and neointimal hyperplasia differ significantly according to DES type. (Optical Coherence Tomography for Drug Eluting Stent Safety [ODESSA]; NCT00693030).

Different Vascular Healing Patterns With Various Drug-Eluting Stents in Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction: Optical Coherence Tomographic Findings

The introduction of optical coherence tomography has provided a new method for evaluating the vascular response to drug-eluting stents (DESs). We used optical coherence tomography to compare neointimal coverage and stent malapposition among DESs in patients with ST-segment elevation myocardial infarction. Optical coherence tomography was performed at 9 months after implantation of 3 types of DESs at the culprit lesions in 46 patients with ST-segment elevation myocardial infarction (16 sirolimus-eluting stents [SESs, Cypher Select], 11 paclitaxel-eluting stents [PESs, Taxus Liberte], and 19 zotarolimus-eluting stents [ZESs, Endeavor Sprint]). The neointimal thickness and apposition at each strut at each 1-mm interval and the presence of thrombi in each stent were evaluated. A total of 11,512 stent struts were analyzed. SESs had the thinnest neointimal thickness (SES 62 +/- 43 mum vs PES 244 +/- 142 mum vs ZES 271 +/- 128 mum, p <0.001). The incidence of uncovered struts and malapposed struts were significantly greater in SESs and PESs than in ZESs (SES vs PES vs ZES, 16.2 +/- 17.8% vs 4.7 +/- 7.4% vs 0.6 +/- 1.5%, respectively, p = 0.001; and 4.0 +/- 8.2% vs 2.1 +/- 4.5% vs 0 +/- 0%, respectively, p = 0.001). Thrombus was also detected more often in SESs and PESs than in ZESs (SES, 6 [38%] vs PES, 3 [27%] vs ZES, 1 [5%], p = 0.02). In conclusion, the rate of stent strut coverage and malapposition were significantly different among the DES types in ST-segment elevation myocardial infarction. In particular, most stent struts in ZESs were covered with neointima and well-apposed. These findings imply that the type of DES might affect the vascular response in thrombotic lesions of ST-segment elevation myocardial infarction.

Rapid Evaluation of Vessel HEaling After AngiopLasty (REVEAL) trial: rationale, objectives and design

Novel approaches to modify stents have been developed to address the limitations of bare-metal stents (BMS) and drug-eluting stent (DES), aiming for ideal features, such as decreased restenosis rates with decreased thrombogenicity and without the need for long-term dual antiplatelet therapy. The Assessment of The LAtest Non-Thrombogenic Angioplasty Stent (ATLANTA) trial was the first-in-man study to show the safety and efficacy of the Polyzene-F coated CATANIA stent (CeloNova BioSciences, Newnan, Georgia, USA) as an alternative to both BMS and DES. The stent was found to be associated with a good clinical outcome with no vessel thrombosis and a modest growth of late neointima. A subgroup undergoing optical coherence tomography late assessment showed almost complete stent strut coverage at 6 months. However, whether the CATANIA stent is superior in promoting a greater stent strut coverage rate both at 7 and 30 days with respect to DES and BMS is unknown. The Rapid Evaluation of Vessel HEaling After AngiopLasty (REVEAL) trial will be a prospective, randomized study providing new evidence on early vessel healing and thrombus development after stenting with different stent types. Optical coherence tomography examination at 7-10 days or 28-32 days after implantation will evaluate strut coverage and vessel healing. The primary endpoint will be a comparison of the percentage of 'healed stent struts' at 28-32 days, identified by the presence of an evenly apposed rim of tissue on stent struts, and without apposition of thrombotic material, on the total amount of analyzed struts for the stent groups.

Comparison of Neointimal Coverage of Sirolimus-Eluting Stents and Paclitaxel-Eluting Stents Using Optical Coherence Tomography at 9 Months After Implantation

The differences between using sirolimus-eluting stents (SESs) and paclitaxel-eluting stents (PESs) in the vascular response at 9 months after implantation were examined with optical coherence tomography (OCT). OCT was carried out in 33 SESs [33 patients, 19 with acute coronary syndrome (ACS) and 14 with stable angina pectoris (SAP)] and 27 PESs (27 patients, 15 with ACS and 12 with SAP) at 9 months after stent implantation. Stent strut coverage and apposition at each strut were evaluated. The frequency of uncovered struts was significantly higher in SES (12.5+/-15.2 vs 4.9+/-7.9 %, P=0.01). The incidence of complete covered stents with neointima was 9.1% (3/33) in SES and 29.6% (8/27) in PES (P=0.05). The pattern of neointima in PES was more heterogeneous than that in SES (1.3+/-0.5 for SES vs 2.0+/-0.6 for PES, P<0.001). The intracoronary thrombus was frequently detected in SES [10 (30.3%) in SES vs 5 (18.5%) in PES, P=0.29]. Uncovered struts were frequently observed in SES, but the pattern of neointima was more heterogeneous in PES at 9 months. In addition, stent coverage was incomplete in both stent groups at 9 months after stent implantation.

An optical coherence tomography study of a biodegradable vs. durable polymer-coated limus-eluting stent: a LEADERS trial sub-study

Incomplete endothelialization has been found to be associated with late stent thrombosis, a rare but devastating phenomenon, more frequent after drug-eluting stent implantation. Optical coherence tomography (OCT) has 10 times greater resolution than intravascular ultrasound and thus appears to be a valuable modality for the assessment of stent strut coverage. The LEADERS trial was a multi-centre, randomized comparison of a biolimus-eluting stent (BES) with biodegradable polymer with a sirolimus-eluting stent (SES) using a durable polymer. This study sought to evaluate tissue coverage and apposition of stents using OCT in a group of patients from the randomized LEADERS trial. Fifty-six consecutive patients underwent OCT during angiographic follow-up at 9 months. OCT images were acquired using a non-occlusive technique at a pullback speed of 3 mm/s. Data were analysed using a Bayesian hierarchical random-effects model, which accounted for the correlation of lesion characteristics within patients and implicitly assigned analytical weights to each lesion depending on the number of struts observed per lesion. Primary outcome was the difference in percentage of uncovered struts between BESs and SESs. Twenty patients were included in the analysis in the BES group (29 lesions with 4592 struts) and 26 patients in the SES group (35 lesions with 6476 struts). A total of 83 struts were uncovered in the BES group and 407 out of 6476 struts were uncovered in the SES group [weighted difference -1.4%, 95% confidence interval (CI) -3.7 to 0.0, P = 0.04]. Results were similar after adjustment for pre-procedure lesion length, reference vessel diameter, number of implanted study stents, and presence of stent overlap. There were three lesions in the BES group and 15 lesions in the SES group that had > or =5% of all struts uncovered (difference -33.1%, 95% CI -61.7 to -10.3, P < 0.01). Strut coverage at an average follow-up of 9 months appears to be more complete in patients allocated to BESs when compared with SESs. The impact of this difference on clinical outcome and, in particular, on the risk of late stent thrombosis is yet to be determined.

Drug-Eluting Stents in Animals and Patients

Four legs good, two legs better. — —George Orwell, Animal Farm, 1945 Since the earliest use of coronary stents for treating symptomatic coronary stenosis, maintaining patent arteries after treatment has remained an elusive goal. Although the first bare metal stents opened stenotic arteries, they injured the arterial wall. The buildup of intimal scar tissue caused restenosis, a frustrating problem for prevention or treatment. After a dozen years of research, however, drug-eluting stents were developed; armed with polymer coating and paclitaxel or sirolimus, they prevented restenosis and were hailed as a major therapeutic breakthrough. Article see p 141 Not long afterward, however, questions about the safety and efficacy of drug-eluting stents surfaced as reports of late stent thrombosis began to appear.1,2 Cardiologists wondered if prevention of restenosis was always a good thing. If no protective cellular layer formed over the struts of the drug-eluting stent—even months or years after implantation—would thrombus develop on the exposed metal scaffolding or other damaged or inflamed areas on the blood vessel wall? Over months or years, would progressive inflammation or late “catchup” tissue growth cause drug-eluting stents to lose their early advantage over bare metal stents? The pendulum in this debate has swung back and forth as clinical trials first raised concern about increased thrombosis and then later quelled our fears as our understanding of how drug-eluting stents work in real life has matured. An important issue has been the increased use of stents in patients with more complex coronary and other disorders, raising the question of whether the established standards of safety and efficacy still apply. Answers for these challenging questions have come from 2 worlds: clinical studies of patients with stents …

A Randomized Optical Coherence Tomography Study of Coronary Stent Strut Coverage and Luminal Protrusion With Rapamycin-Eluting Stents

We used optical coherence tomography, which has a resolution of <20 microm, to analyze thin layers of neointima in rapamycin-eluting coronary stents. Lack of neointimal coverage has been implicated in the pathogenesis of drug-eluting coronary stent thrombosis. Angiography and intracoronary ultrasound lack the resolution to examine this. We conducted a randomized trial in patients receiving polymer-coated rapamycin-eluting stents (Cypher, Cordis, Johnson & Johnson, Miami, Florida) and nonpolymer rapamycin-eluting stents (Yukon, Translumina, Hechingen, Germany) to examine neointimal thickness, stent strut coverage, and protrusion at 90 days. Twenty-four patients (n = 12 for each group) underwent stent deployment and invasive follow-up at 90 days with optical coherence tomography. The primary end point was binary stent strut coverage. Coprimary end points were neointimal thickness and stent strut luminal protrusion. No patient had angiographic restenosis. For polymer-coated and nonpolymer rapamycin-eluting stents, respectively, mean (SD), neointimal thickness was 77.2 (25.6) microm versus 191.2 (86.7) mum (p < 0.001). Binary stent strut coverage was 88.3% (11.8) versus 97.2% (6.1) (p = 0.030). Binary stent strut protrusion was 26.5% (17.5) versus 4.8% (8.6) (p = 0.001). Mean neointimal thickness for the polymer-coated rapamycin-eluting stent was significantly less than the nonpolymer rapamycin-eluting stent but as a result coverage was not homogenous, with >10% of struts being uncovered. High-resolution imaging allowed development of the concept of the protrusion index, and >25% of struts protruded into the vessel lumen with the polymer-coated rapamycin-eluting stent compared with <5% with the nonpolymer rapamycin-eluting stent. These findings may have important implications for the risk of stent thrombosis and, therefore, future stent design. (An optical coherence tomography study to determine stent coverage in polymer coated versus bare metal rapamycin eluting stents. ORCA 1, from the Optimal Revascularization of the Coronary Arteries group; ISRCTN42475919).

Optical Coherence Tomographic Results at Six-Month Follow-Up Evaluation of the CATANIA Coronary Stent System With NanoThin Polyzene-F Surface Modification (from the Assessment of The LAtest Non-Thrombogenic Angioplasty Stent [ATLANTA] Trial)

Drug-eluting stents were devised as an answer to restenosis, but research has shown that the eluting drug can interfere with the blood vessel's healing process, thus increasing the risk of stent thrombosis. A stent coated with the new proprietary polymer Polyzene-F, is a novel technical solution that promises to decrease in-stent restenosis and tackle the risk of thrombosis. Fifty-five patients were enrolled in the first clinical human study (ATLANTA registry), addressing the short-term follow-up results of the CATANIA stent with Polyzene-F. As a part of the study protocol, 15 patients were randomly assigned to optical coherence tomographic (OCT) examination at 6-month follow-up. Optical coherence tomograms were obtained using a Lightlab M2 system with a motorized pull-back at 2.0 mm/s. OCT images were acquired at 15.6 frames/s. A total of 1,904 cross-sectional images with 19,028 struts were analyzed. The rate of covered struts was 99.5%, whereas malapposed struts accounted for 0.15%. Area measurements were performed in 476 cross sections. Neointimal hyperplasia (NIH) area and percent NIH area were 3.2 +/- 1.4 mm2 and 38 +/- 17%, respectively. Percent NIH area was comparable between diabetics and nondiabetics. Qualitative assessment of OCT images demonstrated neither occurrence of stent fractures nor thrombus. In conclusion, OCT assessment of the Polyzene-F-covered stent at follow-up showed a small percentage of neointima. Also, almost complete stent strut coverage was revealed by optical coherence tomography. These figures indicate that the CATANIA stent with Polyzene-F is a promising solution for decreasing late stent restenosis and preventing thrombosis.

Abstract 3329: Discontinuation of Antiplatelet Therapy Correlates with Angioscopic Subclinical Thrombus After Sirolimus Eluting Stent Implantation

Background: Although some stent thorombois seems to be correlated with discontinuation of antiplatelet therapy, the suitable duration of antiplatelet therapy after silorimus eluting stent (SES) implantation is unknown. In this study, we evaluated effects of discontinuation of one of dual antiplatelet therapy on angioscopic subclincal thrombus in the patients who received dual antiplatelet therapy after SES implantation. Methods: Six-month follow-up angioscope was performed in 110 consecutive patients with SES implantation. We divided our patients into two groups randomly: the patients who received dual antiplatelet theraphy (aspirin (100mg) and ticlopidine (200mg)/day) until 6-month follow-up angioscope (D-group) and the patients who stopped ticlopidine at 3 months after SES implantation (continued to receive only aspirin) (S-group). We compared the following parameters between the two groups: angioscopic parameters including existence of visible thrombus, grades of neointimal coverage (0: no neointimal coverage of stent struts, 1: partial coverage, 2: complete coverage), plaque color around stent (0: white, 1: yellow) and coronary risk factors including hypertension, hypercholesterolemia, smoking, diabetes mellitus and hemodialysis. Results: Incidence of angioscopic visible thrombus in S-group was significalty higher than that in D group, while there were no significant differences of the other pamameters between the two groups (table ). Two patients among S-group (3%) and one patient among D group (2%) received revascularization therapy at 6 months after SES implanation (n.s.). All the study patients revealed no other major adverse cardiac events (MACE); death, acute myocardial infarction and coronary bypass surgery. Conclusions: Only three months discontinuation of ticlopidine may affect on product of angioscopic sublicnical thrombus, however it was not correlated with MACE during 6 months follow-up after SES implantation.

Neointimal coverage of bare-metal and sirolimus-eluting stents evaluated with optical coherence tomography

Objective: To analyse the neointimal coverage of sirolimus-eluting stent (SES) and bare-metal stent (BMS) visualised in vivo by optical coherence tomography (OCT). Methods: OCT images were obtained in 26 coronary...

Late Coronary Stent Thrombosis

Introduced >20 years ago,1 coronary artery stents have improved the safety and particularly the efficacy of percutaneous coronary interventions (PCIs).2 Abrupt vessel closure, complicating 6% to 8% of balloon angioplasty procedures, was associated with a 5% mortality, 40% rate of myocardial infarction (MI), and 40% rate of emergency coronary artery bypass grafting.3 Stents significantly reduced these adverse events (Figure 1).4,5 The reduction of restenosis afforded by bare metal stents (BMS) was modest (30% to 40%). Repeat revascularization still occurred in 15% to 20% of cases.6 Drug-eluting stents (DES) with antiproliferative drugs attached via polymers on the stent surface to minimize smooth muscle proliferation have reduced restenosis and rates of target lesion revascularization by 50% to 70% compared with BMS across nearly all lesion and patient subsets.7 Initially8 and again more recently,9–16 safety concerns were raised about DES, particularly about late stent thrombosis (ST). Figure 1. Outcome of 112 patients with abrupt vessel closure in the prestent balloon angioplasty experience of a registry (1985 to 1986; total, 1801 patients)3 and 339 patients with abrupt vessel closure during balloon angioplasty treated with BMS (Palmaz-Schatz) (total, 4596 patients).5 CABG indicates coronary artery bypass grafting. ST was a bane of stent implantation from the beginning. The initial experience with Wallstents in the late 1980s was overshadowed by ST rates approaching 24%.17 Subsequent series with Palmaz-Schatz and Gianturco-Roubin stents (still predominantly bailout stenting) observed ST in 6% to 12% of cases.4,18 The postprocedural antithrombotic regimen at the time consisted of aspirin, often in conjunction with oral anticoagulation. Dual antiplatelet therapy of aspirin and the thienopyridine ticlopidine in conjunction with a shift from bailout to elective stenting resulted in a significant reduction of ST to <2%.5,19 Earlier oral antiplatelet drug loading and …

Does optical coherence tomography identify arterial healing after stenting? An in vivo comparison with histology, in a rabbit carotid model

Objective:To verify whether optical coherence tomography (OCT) can accurately monitor the occurrence of arterial healing after stenting.Setting:Delayed stent endothelialisation may predispose to stent thrombosis. OCT is a high-resolution intravascular imaging...

Incomplete Neointimal Coverage of Sirolimus-Eluting Stents: Angioscopic Findings

The goal of this study was to use angioscopy to investigate the amount of neointimal coverage after sirolimus-eluting stent (SES) implantation. Sirolimus-eluting stents reduce intimal hyperplasia. We used angioscopy to evaluate 37 consecutive stented coronary artery lesions (15 SES and 22 bare-metal stents [BMS]) in 25 patients (18 men, 7 women) at 3 to 6 months after stent implantation. Angioscopic evaluation focused on: 1) neointimal coverage of stent struts, and 2) the existence of thrombi. The degree of neointimal coverage was classified as grade 0 when there was no neointimal coverage (similar to immediately after the implantation); grade 1 when stent struts bulged into the lumen, but were covered and still translucently visible; grade 2 when stent struts were visible but not clearly seen (not translucent); and grade 3 when stent struts were not visible because they were embedded in the neointima. Thrombi were identified in eight stented segments, tended to be more common with SES (p = 0.14), but were not seen on angiography. Three of the 15 SES (20%) had grade 0 neointimal coverage, and only 2 SES (13.3%) had complete coverage (grades 2/3). In contrast, all 22 BMS showed complete intimal coverage (grades 2/3). Thrombi were more common in stents with incomplete neointimal coverage (p = 0.09). The SES had incomplete neointimal coverage three to six months after implantation, and this was associated with subclinical thrombus formation.