Serial Angioscopic Evidence of Incomplete Neointimal Coverage After Sirolimus-Eluting Stent Implantation

The possibility of delayed arterial healing 5 years after implantation of sirolimus-eluting stents: serial observations by coronary angioscopy

BACKGROUND

Although very late stent thrombosis occurs several years after implantation of sirolimus-eluting stent (SES), the morphologic changes of the stent beyond 2 years have not yet been systematically studied in living patients. The late vascular response to SES was therefore evaluated by serial angioscopic studies at 2 and 5 years after stent implantation.

METHODS

A total of 17 patients with 17 SES underwent a repeated angioscopy procedure at 2 and 5 years. Neointimal stent coverage (NSC) was classified as follows: grade 0, presence of uncovered struts; grade 1, visible struts through a thin neointima; or grade 2, complete neointimal coverage without visible struts. For each patient, the minimum and maximum NSC grade and the existence of in-stent thrombus were recorded.

RESULTS

The minimum and maximum NSC grade did not increase between the 2 and 5 years (0.59 ± 0.51 vs 0.88 ± 0.70, P = .17, and 1.82 ± 0.39 vs 1.94 ± 0.24, P = .30, respectively). The prevalence of patients with uncovered struts did not significantly decrease from 2 to 5 years (41% vs 29%, P = .49). During the follow-up period, 3 of 6 thrombi disappeared, whereas new thrombus formation was found in 3 patients without any clinical symptoms. In-stent thrombus did not decrease (35% vs 35%, P > .99).

CONCLUSIONS

The current serial angioscopic study suggests that incomplete NSC and the prevalence of latent thrombus within the SES segments did not decrease from 2 to 5 years. The risk of stent thrombosis related to incomplete healing of SES may continue for an extended period.

Serial angioscopic evaluation of neointimal coverage and incidence of thrombus formation after Paclitaxel-eluting stent implantation: comparison between 6- and 18-month follow-up

BACKGROUND

Long-term serial angioscopic follow-up data after paclitaxel-eluting stent (PES) implantation has not previously been published. The aim of this study is to compare the angioscopic parameters such as neointimal coverage grade and prevalence of red mural thrombus at 6- and 18-month follow-up after PES implantation.

HYPOTHESIS

Neointimal formation continues to grow and prevalence of angioscopic thrombus formation becomes low over time after PES implantation.

METHODS

We retrospectively enrolled 17 patients with 19 stents who underwent both 6- and 18-month follow-up coronary angioscopy after PES implantation. We evaluated the minimum and maximum neointimal coverage grade within 1 stent using coronary angioscopy by classifying neointimal coverage grade into 4 categories. Neointimal coverage grade and incidence of angioscopic red mural thrombus were compared between 6- and 18-month follow-up groups.

RESULTS

Minimum neointimal coverage grade at 18 months become lower than that at the 6-month follow-up (0.95 ± 0.62 at 6 mo vs 0.58 ± 0.51 at 18 mo, P = 0.035), whereas maximum grade was not significantly different (2.16 ± 0.83 at 6 mo vs 2.37 ± 0.76 at 18 mo, P = 0.248). High incidence of angioscopic red mural thrombus at 6 months was maintained even at 18-month follow-up (68% at 6 mo vs 84% at 18 mo, P = 0.224).

CONCLUSIONS

Long-term serial angioscopic follow-up demonstrated persistent high incidence of red mural thrombus formation at 18 months after PES implantation.

Coronary angioscopy: current topics and future direction

Disruption of vulnerable plaque and following thrombus formation are considered the main cause of acute coronary syndrome (ACS). Intracoronary angioscopy is an endoscopic technology that allows direct visualization of the coronary artery lumen and provides detailed information regarding plaque morphology in patients with coronary artery disease. The color and morphology of coronary plaque under angioscopy observation are proposed to be determinants for plaque stability. Angioscopically yellow plaque represents a thin-cap fibroatheroma, and is associated with a higher incidence of disruption and thrombus formation, and may be associated with future acute coronary syndromes. To circumvent the subjectivity of color interpretation, various quantitative methods have been proposed for identifying vulnerable plaques. Superior to other coronary imaging techniques such as VH IVUS and optical coherence tomography, angioscopy has impressively high sensitivity and specificity in detection of intraluminal thrombus. Angioscopy can also be used as an adjunctive technique during catheter intervention by directly visualizing the thrombus, stent struts and proliferating neointima. The time course and pattern of neointima coverage, as seen by angioscopy, various among different stent systems. Angioscopic assessment of serial changes after stent implantation may have potential benefits on patient's management after coronary stenting.

The evolving role of inflammatory biomarkers in risk assessment after stent implantation

The main adverse reactions to coronary stents are in-stent restenosis (ISR) and stent thrombosis. Along with procedural factors, individual susceptibility to these events plays an important role. In particular, inflammatory status, as assessed by C-reactive protein levels, predicts the risk of ISR after bare-metal stent implantation, although it does not predict the risk of stent thrombosis. Conversely, C-reactive protein levels fail to predict the risk of ISR after drug-eluting stent (DES) implantation, although they appear to predict the risk of stent thrombosis. Of note, DES have abated ISR rates occurring in the classical 1-year window, but new concern is emerging regarding late restenosis and thrombosis. The pathogenesis of these late events seems to be related to delayed healing and allergic reactions to polymers, a process in which eosinophils seem to play an important role by enhancing restenosis and thrombosis. The identification of high-risk individuals based on biomarker assessment may be important for the management of patients receiving stent implantation. In this report, we review the evolving role of inflammatory biomarkers in predicting the risk of ISR and stent thrombosis.

Optical coherence tomography endpoints in stent clinical investigations: strut coverage

Late stent thrombosis (LST) and very LST (VLST) are infrequent complications after drug-eluting stent (DES) implantation, but they carry a significant risk for patients. Delayed healing, which may be represented by incomplete stent coverage, has been observed in necropsy vessel specimens treated with DES. As a result, in vivo assessment of stent coverage, as well as stent apposition using optical coherence tomography (OCT), have been recently used as surrogate safety endpoints in clinical trials testing DES platforms. By adopting strut coverage assessed by OCT, one can assess the safety profile of the new generation of DES in preregistration studies. This article focuses on stent strut coverage as a central predictor of late DES thrombosis from the histopathological point of view, discusses the limitations of the current imaging modalities and presents the technical characteristics of OCT for the detection of neointimal coverage after stent implantation. We also review the preclinical and clinical investigations using this novel imaging modality.

Strut coverage and late malapposition with paclitaxel-eluting stents compared with bare metal stents in acute myocardial infarction: optical coherence tomography substudy of the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) Trial

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.

The Management of Antiplatelet Therapy in Patients With Coronary Stents Undergoing Noncardiac Surgery

Whereas the development of coronary stents has been a major breakthrough in the treatment of coronary artery disease, stent thrombosis, associated with myocardial infarction and death, has introduced a new challenge in the care of patients with coronary stents undergoing noncardiac surgery. This review presents the authors’ recommendations regarding the optimal management of such patients. Elective surgery should be postponed for at least 6 weeks and optimally 3 months for a bare-metal stent and at least 1 year for a drug-eluting stent. On the other hand, managing a patient undergoing non-elective surgery is more difficult and necessitates a case-by-case assessment of bleeding risk versus thrombotic risk based on patient comorbidities, type of stents present, details of the coronary intervention, and type of surgical procedure. Patients with a risk of bleeding that outweighs the risk of stent thrombosis should discontinue at least clopidogrel, whereas all other patients should continue dual antiplatelet therapy throughout the perioperative period.

Assessment by optical coherence tomography of stent struts across side branch. -Comparison of bare-metal stents and drug-elution stents.-

BACKGROUND

Late stent thrombosis (LST) after drug-eluting stent (DES) implantation is a major clinical problem that has not been fully explained. Incomplete neointimal coverage of stent struts is an important morphometric predictor of LST, which may be associated with impaired healing and the absence of full coverage of struts at branch-point ostia. Optical coherence tomography (OCT) was performed to compare 3 types of stents placed across side branches.

METHODS AND RESULTS

At 9-month follow-up, the neointimal coverage of the struts of 58 stents across a side branch was measured by OCT (bare metal (BMS), n = 20; sirolimus-eluting (SES), n = 23; paclitaxel-eluting (PES), n = 15). According to the diameter ratio of side branch to main vessel, the side branches were classified as either large (ratio > 0.33) or small (ratio ≤ 0.33). BMS had the lowest frequency of uncovered struts (29.4%) and the greatest neointimal thickness on the struts (123 ± 33 µm). Neointimal thickness on the struts was less for SES than for PES (72 ± 16 vs. 91 ± 22 µm, P = 0.009), but there was no difference in the frequency of uncovered struts (66.1% vs. 58.6%, P=0.493). For large side branches, the frequency of uncovered struts was greater than in the small group for SES (87.5% vs. 40.7%, P = 0.0002) and PES (83.3% vs. 18.2%; P = 0.0013); there was no significant difference for BMS (43.8% vs. 16.7%, P = 0.138).

CONCLUSIONS

Neointimal coverage on struts across a side branch was less frequently observed in DES than in BMS, particularly in large side branches.

Prevention of the renarrowing of coronary arteries using drug-eluting stents in the perioperative period: an update

The management of patients scheduled for surgery with a coronary stent, and receiving 1 or more antiplatelet drugs, has many controversies. The premature discontinuation of antiplatelet drugs substantially increases the risk of stent thrombosis (ST), myocardial infarction, and cardiac death, and surgery under an altered platelet function could also lead to an increased risk of bleeding in the perioperative period. Because of the conflict in the recommendations, this article reviews the current antiplatelet protocols after positioning a coronary stent, the evidence of increased risk of ST associated with the withdrawal of antiplatelet drugs and increased bleeding risk associated with its maintenance, the different perioperative antiplatelet protocols when patients are scheduled for surgery or need an urgent operation, and the therapeutic options if excessive bleeding occurs.

Late Vascular Responses From 2 to 4 Years After Implantation of Sirolimus-Eluting Stents

Background—

Late vascular responses after implantation of drug-eluting stents may play a key role in steadily increasing occurrence of very late stent thrombosis have not yet been fully investigated in human beings.

Methods and Results—

Serial optical coherence tomography observations at 2 and 4 years were collected for 17 patients treated with 21 sirolimus-eluting stents. Corresponding 376 cross sections within single-stent segments at intervals of 1 mm were selected for analyses, and neointimal thickness on each strut was measured. Extrastent lumen (ESL) was defined as an external lumen of the stent. Area and angle of ESL were measured. A total of 3369 and 3221 struts were identified at 2 and 4 years, respectively. From 2 to 4 years, mean neointimal thickness increased (76.8±75.6 μm versus 123.0±102.5 μm; P <0.0001), whereas frequency of patients with uncovered struts decreased (88% versus 29%; P =0.002). Although prevalence of patients that had ESL was similar (59% of 2 years versus 65% of 4 years; P =1.0), the cross sections with ESL increased (9.6% versus 15.2%; P =0.02). Moreover, area and angle of ESL increased from 2 to 4 years (0.28±0.27 mm 2 versus 0.62±0.68 mm 2 and 16.6±5.4° versus 65.1±38.4°; P <0.01, respectively). The incidence of subclinical thrombus did not decrease (24% at 2 years versus 29% at 4 years; P =1.0). All thrombi were identified in patients who had cross sections with ESL.

Conclusions—

The current serial optical coherence tomography study showed an augmentation of neointimal growth at the late phase of sirolimus-eluting stent implantation. ESL may contribute to thrombus formation and ESL of sirolimus-eluting stents expanded from 2 to 4 years.

Local determinants of thrombus formation following sirolimus-eluting stent implantation assessed by optical coherence tomography

OBJECTIVES

We conducted this study to assess the prevalence and determinants of subclinical thrombus after sirolimus-eluting stent (SES) implantation.

BACKGROUND

Angioscopic analyses have demonstrated the presence of thrombus is more common than the clinical incidence of SES thrombosis.

METHODS

Fifty-three patients (53 lesions) underwent 6-month follow-up optical coherence tomography. A stent eccentricity index ([SEI] minimum/maximum stent diameter) was determined in each cross section. To evaluate unevenness of neointimal thickness, a neointimal unevenness score ([NUS] maximum neointimal thickness in the cross section/average neointimal thickness of the same cross section) was calculated for each cross section. Average SEI and NUS were calculated for each stent. Major adverse cardiac events were defined as a composite of death, myocardial infarction, and target vessel revascularization.

RESULTS

Fourteen cases of thrombus (26%) were detected by optical coherence tomography (thrombus: n = 14 vs. nonthrombus: n = 39). The percentage of thrombus was associated with longer stents (36.4 +/- 20.2 mm vs. 25.1 +/- 9.8 mm; p = 0.008), a larger number of uncovered struts (17 +/- 16 vs. 8 +/- 11; p = 0.03), smaller average SEI (0.89 +/- 0.04 vs. 0.92 +/- 0.03; p = 0.001), and greater average NUS (2.22 +/- 0.24 vs. 2.00 +/- 0.33; p = 0.03). A significant relationship existed between average SEI and average NUS (p < 0.0001, R = 0.68), and between average SEI and the number of uncovered struts (p < 0.0006, R = 0.46). There was no significant difference in major adverse cardiac events during follow-up (median: 485 days, 7.1% vs. 12.8%; p > 0.99).

CONCLUSIONS

Longer stents and greater asymmetric stent expansion may be important determinants of thrombus formation after SES implantation. In this small cohort, the presence of thrombus did not increase the risk of major adverse cardiac events.

Angioscopic Evaluation of Neointimal Coverage of Coronary Stents

Drug-eluting stents (DES) reduce coronary restenosis significantly; however, late stent thrombosis (LST) occurs, which requires long-term antiplatelet therapy. Angioscopic grading of neointimal coverage of coronary stent struts was established, and it was revealed that neointimal formation is incomplete and prevalence of LST is higher in DES when compared to bare-metal stents. It was also observed that the neointima is thicker and LST is less frequent in paclitaxel-eluting and zotarolimus-eluting stents than in sirolimus-eluting stents. Many new stents were devised and they are now under experimental or clinical investigations to overcome the shortcomings of the stents that have been employed clinically. Endothelial cells are highly anti-thrombotic. Neo-endothelial cell damage is considered to be caused by friction between the cells and stent struts due to the thin neointima between them which might act as a cushion. Therefore, development of a DES that causes an appropriate thickness (around 100 μm) of the neointima is a potential option with which to prevent neo-endothelial cell damage and consequent LST while preventing restenosis.

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

BACKGROUND

Neointimal formation can protect against thrombosis after sirolimus-eluting stent (SES) implantation; however, promoters of neointimal formation are unknown.

METHODS

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.

RESULTS

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.

CONCLUSION

Vulnerable disease may promote neointimal coverage after SES implantation.

Very late stent thrombosis occurring simultaneously in sirolimus-eluting stents and bare-metal stent in three different coronary vessels

A 36-year-old male was diagnosed with acute inferior myocardial infarction (MI). Emergent coronary angiography (CAG) revealed an occlusive lesion in the distal segment of the right coronary artery (RCA). The proximal and distal sites of the lesion were treated with a bare-metal stent (BMS) and a sirolimus-eluting stent (SES), respectively. Nine days later, he underwent elective percutaneous coronary intervention (PCI). Two SESs were implanted for the stenotic lesion in the left anterior descending artery (LAD), in addition to one SES for the mid-stenotic lesion in the left circumflex artery (LCX). Nine months after PCI, follow-up CAG revealed no restenosis at any stent-implanted site. Two years and 4 months after PCI, he was admitted to our hospital because of acute anterior MI. Emergent CAG revealed total thrombotic occlusion in the in-stent proximal site of LAD. Moreover, thrombotic lesions were also observed in in-stent sites: in both BMS of RCA and SES of LCX. He underwent intracoronary aspiration thrombectomy and plain old balloon angioplasty for LAD using intra-aortic balloon pumping. PCI for the thrombotic lesions in RCA and LCX was not performed. Seventeen days after the stent thrombosis, CAG revealed the complete disappearance of thrombi in LAD, LCX, and RCA.

High incidence of intramural thrombus after overlapping paclitaxel-eluting stent implantation: angioscopic and histopathologic analysis in porcine coronary arteries

BACKGROUND

Systematic analysis of in vivo angioscopy and postmortem histopathology for paclitaxel-eluting stents (PES) has not been previously reported. We assessed 1-month angioscopic and histopathologic sequelae of overlapping PES in pig coronary arteries.

METHODS AND RESULTS

Overlapping PES and bare-metal stents (BMS; n=9, one pair per pig) were implanted, and animals were euthanized at 1 month. Late lumen loss was reduced in PES compared with BMS (0.46+/-0.63 mm versus 1.30+/-0.50 mm; P=0.01). Angioscopically, PES stent struts were clearly visible and accompanied by substantial red material indicating mural thrombi. In contrast, stent struts and mural thrombi were barely visible in BMS (P<0.001 versus PES). Macroscopically, mural thrombi were abundant but distributed irregularly throughout the PES, with greater concentration in overlapping segments. Only occasional mural thrombi were noted for BMS. Microscopically, neointima of BMS was fibrocellular and mature, whereas only a thin layer of immature neointima was seen in PES. Neointimal thickness was less in PES than BMS (0.11+/-0.07 mm versus 0.33+/-0.12 mm; P=0.018). Additionally, extensive para-strut and intramural thrombi, red blood cell debris, and minute luminal thrombi were observed in PES. Despite normal angioscopic appearance of both proximal and distal nonstented reference segments, endothelium-dependent relaxation to substance P was notably diminished (PES, 0+/-7% versus BMS, 10+/-6%; P=0.007), whereas nitroglycerin response was preserved (PES, 9+/-5% versus BMS, 12+/-7%; P=0.34).

CONCLUSIONS

In the porcine coronary model, overlapping PES is associated with marked intramural thrombi, which was accurately detected on angioscopy at 1 month. Moreover, despite normal luminal angioscopic appearance, adjacent nonstented reference segments demonstrated impaired endothelium-dependent vasoreactivity.

Management of Antiplatelet Therapy During Acute Percutaneous Coronary Intervention: New Strategies and Therapeutics

Aggressive intravenous and oral dual antiplatelet therapy has established primary percutaneous coronary intervention (PCI) as the standard of care for acute myocardial infarction. Clopidogrel is currently the thienopyridine of choice for dual antiplatelet therapy in patients treated with PCI. The dose regime and duration of therapy of clopidogrel has undergone multiple refinements. Recently, 2 novel third generation oral inhibitors of P2Y12 receptors, prasugrel and ticagrelor, have undergone clinical evaluation with promising results. This article is a non-exhaustive review of the literature, concentrating on the role of current and novel oral antiplatelet agents for acute myocardial infarction particularly highlighting the limitations and issues associated with clopidogrel use. Key words: Acute myocardial infarction, Clopidogrel, Dual antiplatelet therapy, Prasugrel, Ticagrelor

Does "late catch-up" exist in drug-eluting stents: insights from a serial quantitative coronary angiography analysis of sirolimus versus paclitaxel-eluting stents

BACKGROUND

Recent studies have suggested the possibility of late catch-up after drug-eluting stent implantation. There are limited data on whether late catch-up exists in sirolimus-eluting stents (SESs) and paclitaxel-eluting stents (PESs).

METHODS

Consecutive patients were routinely recommended 2 serial angiographic follow-ups (at 6-9 and 18-24 months post-percutaneous coronary intervention). A serial quantitative coronary angiographic analysis was performed in lesions not receiving target lesion revascularization at first follow-up. Early luminal loss (LL) was defined as the difference in minimal luminal diameter between the first angiographic follow-up and immediate post-percutaneous coronary intervention, and delayed LL was defined as the difference in minimal luminal diameter between the second and first angiographic follow-up.

RESULTS

Four hundred twelve lesions in the main cohort (PES 128, SES 284) and 47 lesions in the secondary hybrid cohort (PES 23, SES 24), which received serial angiographic follow-ups without target lesion revascularization, were included. In the main cohort, early LL was higher in PES compared with SES (0.56 vs 0.20 mm, P < .01), whereas delayed LL occurring after the first angiographic follow-up was higher in SES (0.10 vs 0.28 mm, P < .01), suggesting more prominent late catch-up in SES. Early LL showed better correlation with total LL (correlation coefficient 0.82 vs 0.30) in PES, whereas delayed LL showed better correlation with total LL (correlation coefficient 0.42 vs 0.91) in SES. Such observations were reproducible in the hybrid cohort, where both SES and PES were implanted at index procedure.

CONCLUSION

Late catch-up occurs in both PES and SES with greater delayed late loss in SES. Our data suggest that the process of neointima formation after SES and PES implantation may follow a slightly different timeline.

Bare metal stent implantation for in-stent restenosis with a drug-eluting stent

Following the positioning of a bare metal stent (BMS) implant, a yellow plaque is healed with a reduction of the color grade and thrombogenicity, i.e. vulnerability by angioscopy in the chronic phase ("plaque sealing" of BMS; the "whitening effect" of BMS). However, we have reported that thrombus and yellow plaque increases at the drug-eluting stent (DES) site. A 71-year-old man underwent percutaneous coronary intervention using two DESs for a severe stenotic lesion in his right coronary artery. Follow-up coronary angiography (CAG) showed in-stent restenosis (ISR) at the stent-overlap site. We performed traditional balloon angioplasty, but follow-up CAG showed ISR again at the same position as the first restenosis. In angioscopic findings, the normal vessel wall was white, but the site of DES implantation was yellow and a yellow, soft, swelling neointimal proliferation-like vulnerable plaque was observed at the restenotic site. In expectation of the "whitening effect" of BMS, we implanted a new BMS. As anticipated, follow-up CAG showed no restenosis. Moreover, the angioscopic findings indicated a clean, white, neointimal proliferation-like stable plaque at the BMS implant site in the yellow vulnerable area of DES. The "BMS in DES" therapy should be considered one of the strategies for ISR of DES.

Intracoronary thrombus formation after drug-eluting stents implantation: optical coherence tomographic study

BACKGROUND

Intracoronary thrombus formation after drug-eluting stent (DES) implantation is not sufficiently evaluated.

METHODS

Optical coherence tomography (OCT) was performed in 226 patients (total DES n = 244, sirolimus-eluting stent [SES] n = 95, paclitaxel-eluting stent [PES] n = 62, zotarolimus-eluting stent [ZES] n = 87) after implantation (mean 11 months, range 3-66 months). Using OCT, we investigated the incidence and determinants of intracoronary thrombus.

RESULTS

Intracoronary thrombus was detected in 35 (14%) cases (27 SES [28%], 7 PES [11%], and 1 ZES [1%], P < .001) and was associated with longer stent, smaller stent diameter, and stents at bifurcation lesions. More uncovered stent struts (26 +/- 23 vs 8 +/- 17, P < .001) and malapposed stent struts (6 +/- 14 vs 2 +/- 6, P < .001) were also associated with intracoronary thrombus. Multiple logistic regression analysis found the following determinants of intracoronary thrombus: stent length > or =28 mm (odds ratio [OR] 7.31, 95% CI 1.79-29.86, P = .01), stent diameter <3.0 mm (OR 4.38, 95% CI 1.38-13.97, P = .01), and > or =8 uncovered struts in each stent (OR 3.29, 95% CI 1.07-10.17, P = .04).

CONCLUSIONS

Length, size, and types of DES may be more important than clinical factors in intracoronary thrombus formation after DES implantations.

Coronary angioscopic evaluation for serial changes of luminal appearance after pharmacological and catheter interventions

Although preventive pharmacological therapies effectually reduce the risk of cardiovascular events, acute coronary syndrome (ACS) remains a leading cause of morbidity and mortality in our country, Japan. Disruption of atherosclerotic vulnerable plaques and flow-limiting thrombus formation in non-stent segments of native coronary arteries are considered a main mechanism of ACS. In addition, stent thrombosis originating from implanted metallic coronary stents, so-called vulnerable stents, occasionally appears as ACS in the clinical settings. Coronary angioscopy is a unique imaging modality permitting direct visualization of luminal structures, such as atherosclerotic plaque, thrombus, stent struts, and proliferating neointima. On the basis of accumulated angioscopic findings, intense yellow plaques and stents without neointimal coverage are considered vulnerable plaques and vulnerable stents, respectively. In contrast, morphological disappearance of vulnerable plaques or vulnerable stents by pharmacological and trans-catheter therapies imply stabilization of the plaques or stents. Hence, angioscopic assessment for vulnerability (or stability) of atherosclerotic plaques and implanted stents might be useful for risk classification in the future events of ACS. To evaluate serial changes of coronary lumen after pharmacological and catheter interventions using angioscopy might also provide important information on potential benefits and surrogate endpoints of the therapies and on patients' management.

Incredibly late thromboses in first generation drug eluting stents: a case series

Background

The drug-eluting stents have decreased the incidence of instent restenosis compared to bare metal stents. But, the incidence of late and very late stent thrombosis has increased with the drug-eluting stents.

Case presentation

We are here, reporting three cases of incredibly late instent thrombosis, each one occurring after more than 50 months of drug-eluting stent placement.

Conclusion

The occurrence of stent thrombosis as late as 5 years has been reported in literature. This highlights the importance that there may be no limit to the time duration to the occurrence of very late stent thrombosis and dual antiplatelet therapy with aspirin and clopidogrel may have to be continued indefinitely in patients with drug-eluting stents.

The risk of stent thrombosis in patients with acute coronary syndromes treated with bare-metal and drug-eluting stents

OBJECTIVES

We aimed to evaluate the risk of definite stent thrombosis with bare-metal stents (BMS) and drug-eluting stents (DES) in patients treated for acute coronary syndromes.

BACKGROUND

Acute coronary syndromes (ACS) have been reported as increasing the risk for stent thrombosis.

METHODS

Between January 2000 and December 2005, 5,816 consecutive patients underwent percutaneous coronary intervention for de novo lesions with a single stent type. These patients consisted of 3 sequential groups of BMS (n = 2,248), sirolimus-eluting stents (n = 822) and paclitaxel-eluting stents (n = 2,746). In total, 3,485 patients presented with an ACS.

RESULTS

After a median follow-up of 1,394 days, patients with ACS had a definite stent thrombosis rate of 2.5% versus 1.0% in patients with stable angina (propensity score-adjusted hazard ratio [HR]: 2.80, 95% confidence interval [CI]: 1.72 to 4.56). ACS patients had a higher risk of early and late stent thrombosis, although the increased risk of very late stent thrombosis was only present in ACS patients treated with DES. In stable patients, any stent thrombosis resulted in a significant increase in mortality (adjusted HR: 4.0, 95% CI: 1.7 to 9.3), although this was particularly evident for late or very late stent thrombosis; in contrast only early stent thrombosis significantly increased mortality in patients with acute coronary syndrome patients (adjusted HR: 2.0, 95% CI: 1.0 to 4.1).

CONCLUSIONS

Patients with acute coronary syndromes are at higher risk of early and late stent thrombosis with either BMS or DES, although very late stent thrombosis seems to be uniquely associated with DES. The clinical sequelae of late and very late stent thrombosis are more pronounced in stable patients.

Atherosclerotic and thrombogenic neointima formed over sirolimus drug-eluting stent: an angioscopic study

OBJECTIVES

We sought to examine by angioscopy the neointima formation and thrombogenic potential of the neointima after deployment of a drug-eluting stent (DES).

BACKGROUND

Late stent thrombosis after DES implantation, a major safety concern, has been associated with poor strut coverage by neointima. Intracoronary angioscopy provides a method for visual evaluation of stent coverage by neointima and detection of thrombus in the stented coronary segment.

METHODS

Patients undergoing implantation of a sirolimus DES (n = 57) were serially examined by angioscopy immediately after (baseline) and again at 10 months (follow-up) after implantation. The angioscopic color grade of the neointima from white to yellow was assessed in a semiquantitative manner. Stent coverage was classified into not covered (Grade 0), covered by a thin layer (Grade 1), or buried under neointima (Grade 2). The thrombogenic potential of the neointima was evaluated by the prevalence of thrombus on the neointima.

RESULTS

The maximum yellow color grade of the neointima within DES-implanted lesions increased significantly from baseline to follow-up (1.4 +/- 1.1 vs. 1.9 +/- 0.6, p = 0.0008). Even among lesions without yellow color at baseline, yellow color was detected in 94% (17 of 18) of lesions at follow-up. The prevalence of thrombus was significantly higher on the yellow than on the white neointimal areas. Thrombus was detected on yellow and/or Grade-0/1 neointima, but never on the white Grade-2 neointima.

CONCLUSIONS

Sirolimus DES promoted formation of atherosclerotic yellow neointima in the stent-implanted lesion at 10-month follow-up. Thrombus was detected more often on the yellow area than on the white area and was never detected where a stent was buried under white neointima. These data suggest that the increased potential risk of late stent thrombosis in DES lesions may be due to the newly formed yellow neotima and cholesterol-laden plaque.

The "crush" technique for coronary artery bifurcation stenting: insights from micro-computed tomographic imaging of bench deployments

OBJECTIVES

This study provides insights into "crush" coronary bifurcation stenting through imaging of bench deployments.

BACKGROUND

Although the strategy of provisional side-branch stenting is widely accepted for suitable bifurcation lesions, there is no consensus on the best option for elective stenting with 2 stents. The crush technique has the potential to scaffold and apply the drug to the side-branch ostium where restenosis is most common.

METHODS

Sequential steps of crush stent deployment and post-dilation were undertaken in silicone phantoms and recorded on cine angiography and microcomputed tomography. We assessed the effect of deployment strategies, post-dilation strategies, and cell size on side-branch ostial area.

RESULTS

Side-branch ostial coverage by metal struts was 53% (95% confidence interval [CI]: 46 to 59) after 1-step kissing post-dilation and was reduced by 2-step kissing post-dilation to 33% (95% CI: 28 to 37; p < 0.0001). Although the residual stenosis after the classical crush strategy was 47% (95% CI: 39 to 53), it was 36% (95% CI: 31 to 40; p = 0.002) after mini-crush deployment. Stents with larger cell size (>3.5 mm diameter) had a residual stenosis of 37% (95% CI: 32 to 42) after crush deployment that was less than the residual stenosis for stents with smaller cell size (52%; 95% CI: 44 to 60; p < 0.0001).

CONCLUSIONS

Side-branch ostial stenosis after crush stenting was minimized by mini-crush deployment, 2-step kissing post-dilation, and the use of stents with larger cell size. It is unknown if optimizing stent deployment at bifurcation lesions will reduce clinical stent thrombosis and restenosis.

Comparison of vascular response after sirolimus-eluting stent implantation between patients with unstable and stable angina pectoris: a serial optical coherence tomography study

OBJECTIVES

The aim of the present study was to compare lesion morphologies after sirolimus-eluting stent (SES) implantation between patients with unstable angina pectoris (UAP) and stable angina pectoris (SAP) with the use of optical coherence tomography (OCT).

BACKGROUND

The lesion morphologies before and after coronary stenting have been proposed as important predictors of clinical outcome. The high resolution of OCT provides detailed information of coronary vessel wall.

METHODS

We enrolled 55 patients (UAP: n = 24, SAP: n = 31), and examined lesion morphologies by using OCT at pre- and post-SES implantation and 9 months' follow-up.

RESULTS

The incidence of plaque rupture (42% vs. 3%, p < 0.001), intracoronary thrombus (67% vs. 3%, p < or = 0.001) and thin-capped fibroatheroma (cap thickness <65 microm; 46% vs. 3%, p < 0.001) at pre-intervention was significantly greater in UAP than that in SAP. Although stent profiles and procedural characteristics were not different between the 2 groups, inadequate stent apposition (67% vs. 32%, p = 0.038) and tissue protrusion (79% vs. 42%, p = 0.005) after percutaneous coronary intervention were observed more frequently in patients with UAP. Plaque rupture was significantly increased after percutaneous coronary intervention in patients with UAP (42% to 75%, p = 0.018), and the persistence of core cavity after plaque rupture (28% vs. 4%, p = 0.031) at 9 months' follow-up was observed more frequently in UAP patients compared with SAP patients. At 9 months' follow-up, the incidence of inadequately apposed stent (33% vs. 4%, p = 0.012) and partially uncovered stent by neointima (72% vs. 37%, p = 0.019) was significantly greater in UAP patients than that in SAP patients. All patients took aspirin and ticlopidine during follow-up period, and no patients had stent thrombosis or adverse coronary events.

CONCLUSIONS

Serial OCT examinations demonstrated markedly different vascular response up to 9 months after SES implantation between UAP and SAP patients. Although the inadequate lesion morphologies after stenting were observed more frequently in UAP patients, these findings were not associated with adverse outcomes in patients with antiplatelet therapy.

Noncardiac Surgery and Bleeding After Percutaneous Coronary Intervention

Background— The decision on whether to implant a drug-eluting or bare-metal stent during percutaneous coronary intervention (PCI) depends in part on the perceived likelihood of the patient developing late stent thrombosis. Noncardiac surgery and bleeding are associated with discontinuation of dual antiplatelet therapy and with increased stent thrombosis. We assessed the incidence of and predictors for subsequent noncardiac surgery and bleeding episodes in patients who had undergone PCI.

Methods and Results— Hospital discharge coding data were used to identify all adult patients undergoing public hospital PCI in New Zealand from 1996 to 2001. Hospital admissions during the ensuing 5 years were analyzed for noncardiac surgery and bleeding episodes. Eleven thousand one hundred fifty-one patients (age, 62�11 years; 30% women) underwent PCI, mainly for an acute coronary syndrome (73%). During the 5-year follow-up, 26% of the population underwent at least 1 noncardiac surgical procedure (23% orthopedic, 20% abdominal, 12% urologic, 10% vascular, 35% others) and 8.6% had at least 1 bleeding episode either requiring or occurring during hospitalization. Of those, half were gastrointestinal, and one quarter of bleeding events required blood transfusion. The main clinical predictors of noncardiac surgery were advanced age, previous noncardiac surgery, osteoarthritis, and peripheral vascular disease. A previous bleeding admission and age were the strongest predictors of subsequent bleeding.

Conclusions— Noncardiac surgery is required frequently after PCI, whereas bleeding is less common. Before implanting a drug-eluting or bare-metal stent, individual patient risk stratification by the interventional cardiologist should include assessment of whether there is an increased likelihood of needing noncardiac surgery or developing bleeding.

Comprehensive meta-analysis on drug-eluting stents versus bare-metal stents during extended follow-up

BACKGROUND

Several observational reports have documented both increased and decreased cardiac mortality or Q-wave myocardial infarction with drug-eluting stents compared with bare-metal stents.

METHODS

We sought to evaluate the safety and efficacy of drug-eluting stents compared with bare-metal stents early after intervention (<1 year) and late (>1 year) among a broad population of patients, using a meta-analysis of randomized clinical trials.

RESULTS

We identified 28 trials with a total of 10,727 patients and a mean follow-up of 29.6 months. For early outcomes (<1 year), all-cause mortality for drug-eluting stents versus bare-metal stents was 2.1% versus 2.4% (risk ratio [RR] 0.91, [95% confidence interval (CI), 0.70-1.18]; P=.47), non-Q-wave myocardial infarction was 3.3% versus 4.4% (RR 0.78 [95% CI, 0.61-1.00]; P=.055), target lesion revascularization was 5.8% versus 18.4% (RR 0.28 [95% CI, 0.21-0.38]; P <.001), and stent thrombosis was 1.1% versus 1.3% (RR 0.87 [95% CI, 0.60-1.26]; P=.47). For late outcomes (>1 year), all-cause mortality for drug-eluting stents versus bare-metal stents was 5.9% versus 5.7% (RR 1.03 [95% CI, 0.83-1.28]; P=.79), target lesion revascularization was 4.0% versus 3.3% (RR 1.22 [95% CI, 0.92-1.60]; P=.16), non-Q-wave myocardial infarction was 1.6% versus 1.2% (RR 1.36 [95% CI, 0.74-2.53]; P=.32) and stent thrombosis was 0.7% versus 0.1% (RR 4.57 [95% CI, 1.54-13.57]; P=.006).

CONCLUSIONS

There was no excess mortality with drug-eluting stents. Within 1 year, drug-eluting stents appear to be safe and efficacious with possibly decreased non-Q-wave myocardial infarction compared with bare-metal stents. After 1 year, drug-eluting stents still have similar mortality, despite increased stent thrombosis. The reduction in target lesion revascularization with drug-eluting stents mainly happens within 1 year, but is sustained thereafter.