Very late stent thrombosis related to incomplete neointimal coverage or neoatherosclerotic plaque rupture identified by optical coherence tomography imaging

Stent Underexpansion Is an Underestimated Cause of Intrastent Restenosis: Insights From RESTO Registry

BACKGROUND

Despite improvement in devices, in-stent restenosis remains a frequent and challenging complication of percutaneous coronary interventions.

METHODS AND RESULTS

The RESTO (Morphological Parameters of In-Stent Restenosis Assessed and Identified by OCT [Optical Coherence Tomography]; study NCT04268875) was a prospective multicenter registry including patients presenting with coronary syndromes related to in-stent restenosis. All patients underwent preintervention OCT analysis, which led to analysis of in-stent restenosis phenotype, number of strut layers, and presence of stent underexpansion. The primary end point was the in-stent restenosis type according to the OCT morphological classification. The 1-year incidence of target vessel failure (a composite of death from cardiac causes, target-vessel myocardial infarction, or ischemia-driven target-vessel revascularization) was assessed. The study included 297 patients. The culprit stent was a drug-eluting stent in 74.2% of cases. OCT analysis revealed the presence of neoatherosclerosis in 57% (52% calcified), neointimal hyperplasia in 43% (58% homogeneous), stent underexpansion (minimal stent area <4.5 mm2) in 43%, and multiple stent layers in 30%. The prepercutaneous coronary intervention OCT analysis modified the operator's strategy for management in 30% of cases. Treatment involved drug-eluting stent implantation in 61.6% and drug-eluting balloon angioplasty in 36.1% of cases with only 63.2% optimal results. The 1-year target vessel failure incidence was 11% (95% CI, 9%-13%). Residual postpercutaneous coronary intervention stent underexpansion was associated with significantly higher target vessel failure incidence (19% [95% CI, 14%-24%] versus 7% [95% CI, 5-9], P=0.01).

CONCLUSIONS

OCT identified neoatherosclerosis and neointimal hyperplasia in comparable proportions. Stent underexpansion was frequent and favored subsequent adverse clinical outcomes.

Healed neointima of in-stent restenosis lesions in patients with stable angina pectoris: an intracoronary optical coherence tomography study

The phenomenon to heal neointimal rupture or thrombus after coronary stenting occurs as well as in native coronary artery. We investigated clinical characteristics and neointimal vulnerability of healed neointima by optical coherence tomography (OCT). We treated 67 lesions by percutaneous coronary intervention for in-stent restenosis (ISR) and conducted OCT examinations. Healed neointima was defined as neointima having one or more layers with different optical densities and a clear demarcation from underlying components. ISR with healed neointima was found in 49% (33/67) of the lesions. Compared to ISR without healed neointima, ISR with healed neointima showed significantly longer stent age (102 ± 72 vs. 31 ± 39 months, P < 0.001), lower frequency of dual antiplatelet therapy [42% (14/33) vs. 74% (25/34), P = 0.017], lower use of angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (ACE-I or ARB) [61% (20/33) vs. 91% (31/34), P = 0.028], lower usage of second-generation drug-eluting stents (DESs) [36% (12/33) vs. 63% (22/34), P = 0.029], higher usage of thick-strut stents [42% (14/33) vs. 15% (5/34), P = 0.012], larger neointimal area (6.8 ± 2.6 vs. 5.2 ± 1.8 mm², P = 0.005), higher incidence of thin-cap fibroatheroma [58% (19/33) vs. 21% (7/34), P = 0.002], neointimal rupture [45% (15/33) vs. 9% (3/34), P = 0.001], and lower incidence of stent underexpansion [15% (5/33) vs. 44% (15/34), P = 0.010]. In conclusions, ISR with healed neointima was associated with neointimal vulnerability, stent age, stent type, stent strut thickness, stent expansion, antiplatelet therapy, and use of ACE-I or ARB.

Coronary Stent Healing in Cancer Patients-An Optical Coherence Tomography Perspective

Objective: This study assessed stent healing patterns and cardiovascular outcomes by optical coherence tomography (OCT) in cancer patients after drug-eluting stent (DES) placement.

Background: Cancer treatment, owing to its cytotoxic and antiproliferative effects, could delay stent healing and increase stent thrombosis risk, especially when dual antiplatelet therapy (DAPT) is discontinued early for oncological treatment. OCT can assess stent endothelialization and other healing parameters, which may provide clinical guidance in these challenging scenarios.

Methods: This single-center retrospective study enrolled all cancer patients who underwent OCT for assessment of vascular healing patterns after prior DES placement from November 2009 to November 2018. Primary study endpoints were stent healing parameters, including stent coverage, apposition, degree of expansion, neointimal hyperplasia heterogeneity, in-stent restenosis, stent thrombosis, and overall survival (OS).

Results: A total of 67 patients were included in this study. Mean time between DES placement and OCT evaluation was 154 ± 82 days. Stent healing matched published values for DES in non-cancer patients (P ≥ 0.063). At 1 year, the OS was 86% (95% confidence interval [CI]: 78–96%) with 0% incidence of acute coronary syndrome. Advanced cancers and active chemotherapies were associated with inferior OS (P = 0.024, hazard ratio [HR]: 3.50, 95% CI: 1.18–10.42 and P = 0.026, HR: 2.65, 95% CI: 1.13–6.22, respectively), while stent healing parameters were unassociated with OS. Forty-one patients (61%) had DAPT duration ≤6 months.

Conclusions: Stent healing of contemporary DES appears similar in cancer and non-cancer patients. Cardiovascular risk of cancer patients after DES placement can be managed to facilitate timely cancer therapies, as the underlying malignancy and active chemotherapy ultimately determine survival.

Everolimus-Eluting Biodegradable Abluminal Coating Stent versus Durable Conformal Coating Stent: Termination of the Inflammatory Response Associated with Neointimal Healing in a Porcine Coronary Model

Objectives

We evaluated the effect of the different carrier systems on early vascular response through histological analysis and scanning electron microscopy using a porcine model.

Background

Although Synergy™ and Promus PREMIER™ share an identical stent material and drug elution (everolimus), they use different drug carrier systems: biodegradable abluminal coating polymer or durable conformal coating polymer, respectively. However, data regarding the impact of the different coating systems on vessel healing are currently limited.

Methods

Twelve Synergy™ and Promus PREMIER™ were implanted in 12 swine. Histopathological analysis of the stented segments was performed on the 2^nd and 14^th days after implantation. Morphometric analysis of the inflammation and intimal fibrin content was also performed.

Results

On the 2^nd day, neointimal thickness, percentage of neointimal area, and inflammatory and intimal fibrin content scores were not significantly different between the two groups. On the 14^th day, the inflammatory and intimal fibrin content scores were significantly lower in Synergy™ versus those observed in Promus PREMIER™. In Synergy™, smooth muscle cells were found and the neointimal layers were smooth. In contrast, inflammatory cells were observed surrounding the struts of Promus PREMIER™.

Conclusions

These results demonstrate that termination of reactive inflammation is accelerated after abluminal coating stent versus implantation of conformal coating stent.

Intracoronary Imaging for Assessment of Vascular Healing and Stent Follow-up in Bioresorbable Vascular Scaffolds

Bioresorbable Vascular Scaffolds (BVS) are polymer-based materials implanted in the coronary arteries in order to treat atherosclerotic lesions, based on the concept that once the lesion has been treated, the material of the implanted stent will undergo a process of gradual resorption that will leave, in several years, the vessel wall smooth, free of any foreign material and with its vasomotion restored. However, after the first enthusiastic reports on the efficacy of BVSs, the recently published trials demonstrated disappointing results regarding long-term patency following BVS implantation, which were mainly attributed to technical deficiencies during the stenting procedure. Intracoronary imaging could play a crucial role for helping the operator to correctly implant a BVS into the coronary artery, as well as providing relevant information in the follow-up period. This review aims to summarize the role of intracoronary imaging in the follow-up of coronary stents, with a particular emphasis on the role of intravascular ultrasound and optical coherence tomography for procedural guidance during stent implantation and also for follow-up of bioabsorbable scaffolds.

Impact of vessel curvature on neointimal healing after stent implantation as assessed by optical coherence tomography

PURPOSE

Previous studies have indicated that stent implantation could alter the vessel geometry, which may impact the neointimal healing process. Curvature is an important parameter for evaluating vessel geometry. The purpose of our study was to investigate the relationship between vessel curvature and neointimal healing after stent implantation.

METHODS

Fifty-nine patients with acute coronary syndrome (ACS) who underwent stent implantation were enrolled in the study. According to the post-percutaneous coronary intervention vessel curvature measured by quantitative coronary angiography, patients were divided into high (n = 30) and low (n = 29) curvature groups. Neointimal thickness and area together with the neointimal type were assessed by optical coherence tomography at a 6-month follow-up.

RESULTS

Baseline clinical characteristics were comparable between the 2 groups. The vessel curvature at pre- and 6-month follow-up was significantly higher in the high curvature group than the low curvature group. At 6-month follow-up, neointimal thickness (0.22 [0.08-0.32] mm vs. 0.10 [0.07-0.16] mm, P = .043) and neointimal area (1.86 [0.66-2.66] vs. 0.82 [0.60-1.41] mm, P = .030) were significantly higher in the high curvature group than the low curvature group. In the high curvature group, the incidence of the heterogeneous neointimal type was higher than that in the low curvature group (50.00% vs. 17.20%, respectively, P = .004), whereas the frequency of the homogeneous neointimal type was lower (43.30% vs. 82.80%, respectively, P = .004) in the high curvature group than the low curvature group.

CONCLUSION

Higher vessel curvature after stent implantation may potentially have an impact on the neointimal healing with a higher incidence of heterogeneous neointimal.

Relationship between optical coherence tomography-defined in-stent neoatherosclerosis and out-stent arterial remodeling assessed by serial intravascular ultrasound examinations in late and very late drug-eluting stent failure

BACKGROUND

Little is known regarding the association between chronological out-stent vessel remodeling and in-stent tissue characteristics of drug-eluting stent (DES) failure. We aimed to evaluate the relationship between serial vessel remodeling after DES implantation and neoatherosclerosis (NA) assessed by optical coherence tomography (OCT) in patients with DES failure.

METHODS

Forty-eight patients with late and very late stent failure after DES implantation, who underwent intravascular ultrasound (IVUS) at both the initial percutaneous coronary intervention and the time of stent failure and OCT imaging at the time of stent failure, were retrospectively investigated. NA on OCT was defined as neointimal formation with the presence of lipids or calcification inside the stents. Lesions were divided into two groups: those with NA and those without NA (NA: n=21; non-NA: n=27). From the serial IVUS examinations, external elastic membrane (EEM) volume and out-stent plaque volume were normalized by stent length and their changes were compared between the two groups.

RESULTS

The NA group showed older stent age [median, 5.1 years (IQR, 4.8-8.3) vs 1.4 years (IQR, 0.8-4.5); p<0.01] and more prevalent sirolimus-eluting stents (SES; 81.0% vs. 29.6%; p<0.01). IVUS findings of the NA group showed a greater serial increase in both normalized EEM volume and normalized out-stent plaque volume (OSPVI) [1.05 (0.41-1.90) vs. 0.11 (-0.64 to 0.80) mm²; p<0.01; and 0.88 (0.57-1.98) vs. 0.12 (-0.41 to 0.78) mm²; p<0.01]. On multivariate analysis, percentage change in OSPVI (OR, 1.07; 95% CI, 1.01-1.14; p=0.02) and SES (OR, 9.78; 95% CI, 2.20-43.40; p<0.01) remained independent predictors of NA.

CONCLUSIONS

NA in late and very late DES failure was associated with out-stent positive vessel remodeling. In addition to SES, out-stent progressive positive remodeling may help predict NA in late and very late DES failure.

Clinical Implication of Optical Coherence Tomography-Based Neoatherosclerosis

Recent research has indicated neoatherosclerosis (NA), the de novo development of atherosclerosis within the neointimal region of the stented segment after coronary stent implantation, as a mechanism of late/very late stent thrombosis (VLST) and restenosis. This research is based on histologic and intravascular imaging studies. Optical coherence tomography (OCT) is an imaging tool that is superior with regard to resolution capacity, and can be used to visualize detailed information about distinct morphological characteristics of the restenotic tissue. Thus, OCT is a valuable imaging tool for examining NA, such as macrophage infiltration, lipid accumulation, in-stent calcification, or neointimal rupture. This article discusses the prevalence, predictors, and clinical implications of NA that can be observed by OCT.

A case of in-stent restenosis with pathologically proven chronic inflammation seven years after sirolimus-eluting stent implantation

A 67-year-old man was admitted to our hospital due to chest pain at rest. Seven years previously, the patient underwent percutaneous coronary intervention (PCI) of the left ascending artery and implanted sirolimus-eluting stent (SES). Coronary angioscopy (CAS) performed at that time showed a white plaque at the SES site. Two years after the first PCI, repeat CAS demonstrated light yellow plaques at the SES site. At the time of his presentation to our hospital, coronary angiography showed in-stent restenosis at the SES site, and CAS demonstrated the plaque rupture with presence of dense yellow plaque and various thrombi. After distal protection, drug-eluting balloon treatment was performed. Collected specimens from culprit sites included foamy macrophages, cholesterin crystals, neutrophils, and fibrin, suggesting that progressive neoatherosclerosis at the SES site triggered the acute coronary syndrome. This study highlights the importance of ensuring careful patient follow-up after SES implantation. <Learning objective: After 1st generation drug-eluting stent implantation, careful follow up is warranted, as the process of neoatherosclerosis can be ongoing and contribute to in-stent restenosis.>.

The impact of in-stent neoatherosclerosis on long-term clinical outcomes: an observational study from the Kobe University Hospital optical coherence tomography registry

AIMS

Although pathological studies have indicated the development of neoatherosclerosis (NA) after stenting, its risk factors and impact on future clinical events remain unclear. We aimed to clarify the possible risk factors for NA development and to evaluate the impact of NA in a large Japanese observational OCT database of patients with coronary heart disease.

METHODS AND RESULTS

One hundred and seventy-five consecutive patients (314 lesions) who underwent OCT examination >1 year after bare metal or drug-eluting stent implantation were enrolled. We assessed the presence of NA by follow-up OCT and compared adverse clinical events between NA+ and NA- patients. Forty-six patients had NA at the follow-up OCT. These patients had higher low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) levels at follow-up. In multivariate logistic analysis, LDL cholesterol and CRP levels at follow-up were independently associated with the presence of NA (odds ratio [OR]: 1.022, p=0.008, OR 1.022, p=0.001, respectively). Moreover, patients with NA had a higher incidence of major adverse cardiac events (MACE) at follow-up. Multivariate Cox hazard analysis showed that the presence of NA was an independent risk factor for MACE (hazard ratio: 2.909, p=0.012).

CONCLUSIONS

High LDL cholesterol and CRP levels may be risk factors for NA development in patients treated with coronary stents. Moreover, the presence of NA was independently associated with MACE, suggesting the need for careful clinical follow-up of these patients.

Mechanical abnormalities associated with first- and second-generation drug-eluting stent thrombosis analyzed by optical coherence tomography in the national PESTO French registry

BACKGROUND AND OBJECTIVES

DES thrombosis may be triggered by different mechanisms that are difficult to identify by angiography alone. This work aimed to investigate and compare the characteristics of stent thrombosis (ST) between 1st- and 2nd-generation drug-eluting stents (DES) among a large cohort of patients explored by optical coherence tomography (OCT).

METHODS AND RESULTS

The PESTO study was a prospective national registry involving 29 French catheterization facilities. Patients with acute coronary syndromes were prospectively screened for presence of definite ST and analyzed by OCT after culprit lesion deocclusion. The analysis involved 71 subjects including 34 patients with 1st-generation DES (DES1G) and 35 patients with 2nd-generation DES (DES2G). Most patients (80%) presented with very late stent thrombosis. The median time between initial PCI and ST was longer in DES1G than DES2G patients (3.8 [2.6-6.5] years vs. 1.1 [0.04-2.3] years, p<0.0001). OCT identified an underlying morphological abnormality in 96% of the cases. Significant malapposition was the main abnormality observed either in DES1G (26%) or DES2G patients (35%). Ruptured neoatherosclerotic lesions were more frequently observed with DES1G than with DES2G (26% vs. 3%, p=0.008). There was no significant difference in percentage of malapposed struts and uncovered struts between groups.

CONCLUSIONS

In this registry, DES thrombosis mainly occurred ≥1year after initial PCI. OCT identified a mechanical abnormality in the vast majority of the cases. Similar causes were observed between DES1G and DES2G, but neoatherosclerotic lesions were more common in DES1G.

Characterization of coronary atherosclerosis by intravascular imaging modalities

Coronary artery disease (CAD) is highly prevalent in Western countries and is associated with morbidity, mortality, and a significant economic burden. Despite the development of anti-atherosclerotic medical therapies, many patients still continue to suffer from coronary events. This residual risk indicates the need for better risk stratification and additional therapies to achieve more reductions in cardiovascular risk. Recent advances in imaging modalities have contributed to visualizing atherosclerotic plaques and defining lesion characteristics in vivo. This innovation has been applied to refining revascularization procedure, assessment of anti-atherosclerotic drug efficacy and the detection of high-risk plaques. As such, intravascular imaging plays an important role in further improvement of cardiovascular outcomes in patients with CAD. The current article reviews available intravascular imaging modalities with regard to its method, advantage and disadvantage.

Impact of optical coherence tomography- and coronary angioscopy-assessed neointimal tissue characteristics on occurrence of periprocedural myonecrosis in patients with in-stent restenosis

Several characteristics of neointimal tissues, including neoatherosclerotic progression, have been reported in lesions with in-stent restenosis (ISR). However, the effects of these characteristics on outcomes after percutaneous coronary intervention (PCI) for ISR lesions remain unclear. We assessed the relationships between neointimal tissue characteristics and the occurrence of periprocedural myonecrosis (PMN) after PCI in ISR lesions. We investigated 72 ISR lesions in 72 patients with stable angina pectoris (SAP) who underwent pre- and post-revascularization optical coherence tomography (OCT) and coronary angioscopy (CAS). All lesions were classified as with PMN, defined by an elevated peak high-sensitivity cardiac troponin-T level during the 24-h post-PCI period, and without PMN. PMN was observed in 23 (31.9 %) lesions. PMN lesions had higher frequencies of OCT-derived thin-cap fibroatheroma (26.1 vs. 6.1 %, P = 0.03), CAS-derived intensive yellow neointima (30.4 vs. 10.2 %, P = 0.04), neointima with complex surface (60.9 vs. 28.6 %, P = 0.01), and CAS-derived atheromatous appearance (CAS-AAP), defined as yellow plaque including complex thrombi underneath disrupted neointimal coverage after ballooning (47.8 vs. 16.3 %, P = 0.008) at the most stenotic sites inside stents, compared to lesions without PMN. Multivariate logistic regression analysis identified CAS-AAP (odds ratio: 3.568, 95 % confidence interval: 1.109-11.475, P = 0.033) as an independent predictor of PMN. For ISR lesions in SAP patients, an OCT- and CAS-based assessment of neointimal tissue characteristics might help to predict the occurrence of PMN.

Angiographic and optical coherence tomography insights into bioresorbable scaffold thrombosis: single-center experience

BACKGROUND

As bioresorbable vascular scaffolds (BVSs) are being increasingly used in complex real-world lesions and populations, BVS thrombosis cases have been reported. We present angiographic and optical coherence tomography (OCT) findings in a series of patients treated in our center for definite bioresorbable scaffold thrombosis.

METHODS AND RESULTS

Up to June 2014, 14 patients presented with definite BVS thrombosis in our center. OCT was performed in 9 patients at the operator's discretion. Angiographic and OCT findings were compared with a control group comprising 15 patients with definite metallic stent thrombosis. In the BVS group, time interval from index procedure to scaffold thrombosis ranged from 0 to 675 days. Incomplete lesion coverage by angiography was identified in 4 of 14 cases, malapposition by OCT in 5 of 9 cases, strut discontinuity in 2 of 9 cases, and underexpansion in 2 of 9 cases. Five patients had discontinued dual antiplatelet therapy, and in 3 of them discontinued dual antiplatelet therapy discontinuation had occurred the week preceding the event. There were no significant differences in angiographic or OCT findings between BVS and metallic stent thrombosis.

CONCLUSIONS

Suboptimal implantation with incomplete lesion coverage, underexpansion, and malapposition comprises the main pathomechanism for both early and late BVS thrombosis, similar to metallic stent thrombosis. Dual antiplatelet therapy discontinuation seems to also be a secondary contributor in several late events. Our observations suggest that several potential triggers for BVS thrombosis could be avoided.

Mechanisms of Very Late Drug-Eluting Stent Thrombosis Assessed by Optical Coherence Tomography

BACKGROUND

The pathomechanisms underlying very late stent thrombosis (VLST) after implantation of drug-eluting stents (DES) are incompletely understood. Using optical coherence tomography, we investigated potential causes of this adverse event.

METHODS AND RESULTS

Between August 2010 and December 2014, 64 patients were investigated at the time point of VLST as part of an international optical coherence tomography registry. Optical coherence tomography pullbacks were performed after restoration of flow and analyzed at 0.4 mm. A total of 38 early- and 20 newer-generation drug-eluting stents were suitable for analysis. VLST occurred at a median of 4.7 years (interquartile range, 3.1-7.5 years). An underlying putative cause by optical coherence tomography was identified in 98% of cases. The most frequent findings were strut malapposition (34.5%), neoatherosclerosis (27.6%), uncovered struts (12.1%), and stent underexpansion (6.9%). Uncovered and malapposed struts were more frequent in thrombosed compared with nonthrombosed regions (ratio of percentages, 8.26; 95% confidence interval, 6.82-10.04; P<0.001 and 13.03; 95% confidence interval, 10.13-16.93; P<0.001, respectively). The maximal length of malapposed or uncovered struts (3.40 mm; 95% confidence interval, 2.55-4.25; versus 1.29 mm; 95% confidence interval, 0.81-1.77; P<0.001), but not the maximal or average axial malapposition distance, was greater in thrombosed compared with nonthrombosed segments. The associations of both uncovered and malapposed struts with thrombus were consistent among early- and newer-generation drug-eluting stents.

CONCLUSIONS

The leading associated findings in VLST patients in descending order were malapposition, neoatherosclerosis, uncovered struts, and stent underexpansion without differences between patients treated with early- and new-generation drug-eluting stents. The longitudinal extension of malapposed and uncovered stent was the most important correlate of thrombus formation in VLST.

Optical Coherence Tomography For the Detection of the Vulnerable Plaque

Morphological characteristics of the atheromatous plaque have been associated with the development of plaque rupture and the pathogenesis of acute coronary syndromes (ACS). Plaques with a specific morphological phenotype that are at high risk of causing ACS are called vulnerable plaques, and can be identified in vivo through the use of intracoronary imaging. Optical coherence tomography (OCT) is a high-resolution intravascular imaging modality that enables detailed visualization of atheromatous plaques. Consequently, OCT is a valuable research tool for examining the role of morphological characteristics of atheromatous plaques in the progression of coronary artery disease and plaque destabilisation, which leads to the clinical manifestation of ACS. This article summarises the pathophysiological insights obtained by OCT imaging in the formation and rupture of the vulnerable plaque.

OCT demonstrating neoatherosclerosis as part of the continuous process of coronary artery disease

Although the advent of drug-eluting stents has reduced the rates of target vessel revascularization, there are observations of ongoing stent failure occurring very late after stent implantation and presenting as very late restenosis or as very late stent thrombosis. The de novo development of atherosclerosis within the neointimal region, called neoatherosclerosis, has been identified as one of the pathomechanisms of these observed late stent failures. The mechanisms of neoatherosclerosis development and its association with stent failure are currently the subject of intensive research. Optical coherence tomography (OCT) is an invasive imaging modality that allows us to visualize the micromorphology of coronary arteries with near-histological resolution, thus providing detailed assessment of the morphological characteristics of the neointima after stent implantation, including neoatherosclerosis. Several OCT studies have tried to provide in vivo insights in the mechanisms of neoatherosclerosis development and its association with late stent failure. This review summarizes the current insights into neoatherosclerosis obtained with OCT and discusses the association of neoatherosclerosis with late stent failure.

Clinical utility of intravascular imaging and physiology in coronary artery disease

Intravascular imaging and physiology techniques and technologies are moving beyond the framework of research to inform clinical decision making. Currently available technologies and techniques include fractional flow reserve; grayscale intravascular ultrasound (IVUS); IVUS radiofrequency tissue characterization; optical coherence tomography, the light analogue of IVUS; and near-infrared spectroscopy that detects lipid within the vessel wall and that has recently been combined with grayscale IVUS in a single catheter as the first combined imaging device. These tools can be used to answer questions that occur during daily practice, including: Is this stenosis significant? Where is the culprit lesion? Is this a vulnerable plaque? What is the likelihood of distal embolization or periprocedural myocardial infarction during stent implantation? How do I optimize acute stent results? Why did thrombosis or restenosis occur in this stent? One of the legacies of coronary angiography is to presume that one technique will answer all of these questions; however, that often has been proved inaccurate in contemporary practice.

Causes of very late stent thrombosis investigated using optical coherence tomography

OBJECTIVE

Very late stent thrombosis (VLST) remains an unresolved problem, and recent reports have indicated that VLST onset can occur in patients treated with both drug-eluting stents (DES) and bare metal stents (BMS). We evaluated the causes of VLST using optical coherence tomography (OCT).

METHODS

OCT was performed in 22 patients (12 DES-treated patients, 10 BMS-treated patients). Because two instances of VLST occurred simultaneously in one case in the DES group, the DES group comprised 13 lesions, while the BMS group comprised 10 lesions. All struts were counted in each frame, and the proportion of uncovered or malapposed struts was calculated based on the overall number of struts in the stent.

RESULTS

The interval from stent implantation to VLST onset was significantly longer in the BMS group. The proportion of uncovered struts and the ratio of malapposed struts were significantly higher in the DES group than in the BMS group. The OCT analysis demonstrated intimal hyperplasia or intimal disruption in all patients in the BMS group. However, in the DES group, severe hyperplasia and/or neoatherosclerosis was observed in only eight lesions (61.5%), while uncovered and malapposed struts were involved in the other lesions.

CONCLUSION

In most BMS-treated lesions, it appeared that VLST was caused by the occurrence of neoatherosclerosis after stent implantation. The causes of VLST in DES-treated lesions are more various and complicated than those observed for BMS-treated lesions.