Deep learning model DeepNeo predicts neointimal tissue characterization using optical coherence tomography

BACKGROUND

Accurate interpretation of optical coherence tomography (OCT) pullbacks is critical for assessing vascular healing after percutaneous coronary intervention (PCI). Manual analysis is time-consuming and subjective, highlighting the need for a fully automated solution.

METHODS

In this study, 1148 frames from 92 OCT pullbacks were manually annotated to classify neointima as homogeneous, heterogeneous, neoatherosclerosis, or not analyzable on a quadrant level. Stent and lumen contours were annotated in 305 frames for segmentation of the lumen, stent struts, and neointima. We used these annotations to train a deep learning algorithm called DeepNeo. Performance was further evaluated in an animal model (male New Zealand White Rabbits) of neoatherosclerosis using co-registered histopathology images as the gold standard.

RESULTS

DeepNeo demonstrates a strong classification performance for neointimal tissue, achieving an overall accuracy of 75%, which is comparable to manual classification accuracy by two clinical experts (75% and 71%). In the animal model of neoatherosclerosis, DeepNeo achieves an accuracy of 87% when compared with histopathological findings. For segmentation tasks in human pullbacks, the algorithm shows strong performance with mean Dice overlap scores of 0.99 for the lumen, 0.66 for stent struts, and 0.86 for neointima.

CONCLUSIONS

To the best of our knowledge, DeepNeo is the first deep learning algorithm enabling fully automated segmentation and classification of neointimal tissue with performance comparable to human experts. It could standardize vascular healing assessments after PCI, support therapeutic decisions, and improve risk detection for cardiac events.

Vascular Healing After Biodegradable Polymer Sirolimus-Eluting Versus Durable Polymer Everolimus-Eluting Stents in Chronic Total Occlusions

BACKGROUND

Biodegradable polymer stents may reduce the risk of neoatherosclerosis and stent thrombosis. Limited data is available for biodegradable polymer sirolimus-eluting stent (BP-SES) and durable polymer drug-eluting stents (DP-EES) in chronic total occlusions (CTO).

AIM

This study was to evaluate healing patterns of BP-SES versus DP-EES in CTO at 3 and 13 months based on optical coherence tomography (OCT).

METHODS

The TARGET-CTO study is a prospective, multicenter, randomized noninferiority controlled trial for BP-SES compared to DP-EES in CTO. In the current predefined subanalysis, 44 consecutive patients underwent OCT follow-up at 3 and 13 months. The primary endpoint was mean neo-intimal thickness at 3 months.

RESULTS

At 3 months, mean neo-intimal thickness was 47.6 ± 15.7 µm in BP-SES and 62.5 ± 37.3 µm in DP-EES (p = 0.384), meeting the noninferiority for BP-SES (pnoninferiority < 0.001). Mean neo-intimal thickness at 13 months was 76.4 ± 34.1 µm in BP-SES and 106.6 ± 54.9 µm in DP-EES (p = 0.086). No significant differences in strut coverage were observed at 3 or 13 months. At 13 months significantly higher percentages of frames with layered neo-intima and neoatherosclerosis were observed in DP-EES compared to BP-SES (p = 0.015 and p = 0.021, respectively).

CONCLUSIONS

BP-SES was noninferior to DP-EES in terms of neo-intimal thickness at 3 months and healing responses at 3-month follow-up were comparable. At 13 months, less advanced neoatherosclerosis patterns were observed in BP-SES as compared to DP-EES.

Widespread Use of Imaging-Guided PCI in Asia: Time for Extended Application

In recent years, a wealth of clinical data has emerged regarding intravascular imaging involving either intravascular ultrasound or optical coherence tomography. This surge in data has propelled the adoption of intravascular imaging-guided percutaneous coronary intervention (PCI) in daily clinical practice. The findings of current randomized clinical trials regarding imaging guidance have lent strong support to the benefits of intravascular imaging-guided PCI. This holds especially true for the diagnosis and treatment of complex lesions, such as left main disease, diffuse long lesions, chronic total occlusion, severely calcified lesions, bifurcations, and in-stent restenosis, as well as in high-risk patients such as those with acute myocardial infarction or chronic kidney disease. During intravascular imaging-guided PCI, operators attempt to achieve stent optimization for maximized benefits of imaging guidance. This paper provides a comprehensive review on the updated clinical data of intravascular imaging-guided PCI and intravascular ultrasound/optical coherence tomography-derived stent optimization criteria.

Plaque burden is associated with minimal intimal coverage following drug-eluting stent implantation in an adult familial hypercholesterolemia swine model

Safety and efficacy of coronary drug-eluting stents (DES) are often preclinically tested using healthy or minimally diseased swine. These generally show significant fibrotic neointima at follow-up, while in patients, incomplete healing is often observed. The aim of this study was to investigate neointima responses to DES in swine with significant coronary atherosclerosis. Adult familial hypercholesterolemic swine (n = 6) received a high fat diet to develop atherosclerosis. Serial OCT was performed before, directly after, and 28 days after DES implantation (n = 14 stents). Lumen, stent and plaque area, uncovered struts, neointima thickness and neointima type were analyzed for each frame and averaged per stent. Histology was performed to show differences in coronary atherosclerosis. A range of plaque size and severity was found, from healthy segments to lipid-rich plaques. Accordingly, neointima responses ranged from uncovered struts, to minimal neointima, to fibrotic neointima. Lower plaque burden resulted in a fibrotic neointima at follow-up, reminiscent of minimally diseased swine coronary models. In contrast, higher plaque burden resulted in minimal neointima and more uncovered struts at follow-up, similarly to patients' responses. The presence of lipid-rich plaques resulted in more uncovered struts, which underscores the importance of advanced disease when performing safety and efficacy testing of DES.

Drug-coated balloon therapy is more effective in treating late drug-eluting stent in-stent restenosis than the early occurring one-a systematic review and meta-analysis

Drug-eluting stent in-stent restenosis (DES-ISR) remains one of the important assignments to be resolved in interventional cardiology, as it is present in 5%-10% of total percutaneous coronary intervention cases. Drug-coated balloon (DCB) utilization is promising, as it comes with long-term protection from recurrent restenosis in optimal conditions without the hazard of higher risk for stent thrombosis and in-stent restenosis. We aim to reduce the need for recurrent revascularization in DES-ISR, specifying the population in which the DCB therapy should be used. In this meta-analysis, the results of studies containing data on the time frame between drug-eluting stent implantation and the clinical presentation of in-stent restenosis and concomitant drug-coated balloon treatment were summarized. A systematic search was performed in Medline, Central, Web of Science, Scopus and Embase databases on November 11th, 2021. The QUIPS tool was used to assess the risk of bias in the included studies. The occurrence of a major cardiac adverse events (MACE) composite endpoint, containing target lesion revascularization (TLR), myocardial infarction, and cardiac death, and each of these separately, was assessed at 12 months after the balloon treatment. Random effects meta-analysis models were used for statistical analysis. Data of 882 patients from four studies were analyzed. Across the included studies, a 1.68 OR (CI 1.57-1.80, p < 0.01) for MACE and a 1.69 OR (CI 1.18-2.42 p < 0.01) for TLR were observed, both in favor of late DES-ISR. The main limitation of the study is the relatively low patient number. Nevertheless, this analysis shows the first statistically significant results for the effect of DCB treatment in the early or late presentation of DES-ISR. As to date, intravascular imaging (IVI) remains limitedly accessible, other landmarks as the time frame of in-stent restenosis development are to be pursued to advance therapeutic outcomes. In consideration of other biological, technical and mechanical factors, time frame of occurrence as a prognostic factor could reduce the burden of recurrent revascularization in patients at an already high risk. Systematic Review Registration: identifier [CRD42021286262].

Optical coherence tomography in coronary atherosclerosis assessment and intervention

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Coronary In-Stent Restenosis: JACC State-of-the-Art Review

The introduction and subsequent iterations of drug-eluting stent technologies have substantially improved the efficacy and safety of percutaneous coronary interventions. However, the incidence of in-stent restenosis (ISR) and the resultant need for repeated revascularization still occur at a rate of 1%-2% per year. Given that millions of drug-eluting stents are implanted each year around the globe, ISR can be considered as a pathologic entity of public health significance. The mechanisms of ISR are multifactorial. Since the first description of the angiographic patterns of ISR, the advent of intracoronary imaging has further elucidated the mechanisms and patterns of ISR. The armamentarium and treatment strategies of ISR have also evolved over time. Currently, an individualized approach using intracoronary imaging to characterize the underlying substrate of ISR is recommended. In this paper, we comprehensively reviewed the incidence, mechanisms, and imaging characterization of ISR and propose a contemporary treatment algorithm.

Management of in-stent restenosis

In-stent restenosis (ISR) remains the most common cause of stent failure after percutaneous coronary intervention (PCI). Recent data suggest that ISR-PCI accounts for 5-10% of all PCI procedures performed in current clinical practice. This State-of-the-Art review will primarily focus on the management of ISR but will begin by briefly discussing diagnosis and classification. We then move on to detail the evidence base underpinning the various therapeutic strategies for ISR before finishing with a proposed ISR management algorithm based on current scientific data.

Effect of Rivaroxaban and Clopidogrel Combination Therapy on In-Stent Responses After Everolimus-Eluting Stent Implantation in a Porcine Coronary Model

AIM

According to recent clinical trials, a combination of direct oral anticoagulants with antiplatelet drugs is often recommended for atrial fibrillation patients who receive drug-eluting stents (DESs). Although the optimal combination comprises direct factor Xa inhibitors and a P2Y12 receptor antagonist (or aspirin), their influence on vascular responses to DESs remains unclear.

METHODS

Pigs were given either aspirin and clopidogrel (dual antiplatelet therapy [DAPT] group), aspirin and rivaroxaban (AR group), or clopidogrel and rivaroxaban (CR group), followed by everolimus-eluting stent (Promus Element) implantation into the coronary artery. Stented coronary arteries were evaluated via intravascular optical coherence tomography (OCT) and histological analysis at 1 and 3 months.

RESULTS

OCT revealed lower neointimal thickness in the DAPT group and comparable thickness among all groups at 1 and 3 months, respectively. Histological analyses revealed comparable neointimal area among all groups and the smallest neointimal area in the CR group at 1 and 3 months, respectively. In the DAPT and AR groups, the neointima continued to grow from 1 to 3 months. A shortened time course for neointima growth was observed in the CR group, with rapid growth within a month (maintained for 3 months). A higher incidence of in-stent thrombi was observed in the AR group at 1 month; no thrombi were found in either group at 3 months. More smooth muscle cells with contractile features were found in the CR group at both 1 and 3 months.

CONCLUSIONS

Our results proved the noninferiority of the combination of rivaroxaban with an antiplatelet drug, particularly the dual therapy using rivaroxaban and clopidogrel, compared to DAPT after DES implantation.

Temporal Course of Vascular Response After Fluoropolymer Paclitaxel-Eluting Stent Implantation for Femoropopliteal Artery Lesions

BACKGROUND

Limited data are available regarding the vascular response after fluoropolymer paclitaxel-eluting stent (FP-PES) implantation. This study sought to assess the vascular response at 6 and 12 months after FP-PES implantation for femoropopliteal artery lesions using serial optical coherence tomography (OCT) examination.

METHODS AND RESULTS

From the IMPERIAL trial, this study evaluated 10 de novo femoropopliteal lesions treated with FP-PES. The primary study endpoint was neointimal tissue coverage at a 6- and 12-month follow up, as assessed by serial OCT examination. The incidence of peri-strut low-intensity area (PLIA) and extra-stent lumen (ESL) was also assessed. A total of 203 matched cross-sectional images were evaluated at 6 and 12 months (5,615 and 5,763 struts, respectively). From 6 to 12 months, the mean neointimal thickness tended to increase from 198 µm to 233 µm, with a significant reduction in the incidence of malapposed struts (0.59% vs. 0.28%, P=0.039). Conversely, uncovered struts and PLIA were more frequently observed at 12 months (4.4% vs. 7.8%, P=0.01; 12.7% vs. 21.0%, P<0.001, respectively). The ESL area significantly increased over time without any difference in its incidence (0.24±0.32 mm2vs. 0.38±0.36 mm2, P=0.009).

CONCLUSIONS

Neointimal proliferation was markedly inhibited from 6 to 12 months after FP-PES implantation, whereas the incidence of uncovered struts and PLIA significantly increased over time with the enlargement of ESL.

Early coronary healing in ST segment elevation myocardial infarction: sirolimus-eluting stents vs. drug-coated balloons after bare-metal stents. The PEBSI-2 optical coherence tomography randomized study

OBJECTIVES

Drug-coated balloons (DCBs) have theoretical advantages over drug-eluting stents (DESs) to facilitate stent healing. We studied whether, in patients undergoing primary coronary interventions (pPCIs), a strategy of DCB after bare-metal stent improves early healing as determined by optical coherence tomography (OCT) compared with new-generation DES.

METHODS

pPCI patients were randomized (1:1) to treatment with new-generation sirolimus-eluting stents (DES group) or DCB-strategy. Vessel healing was assessed by OCT at 90 days.

RESULTS

Fifty-three patients were randomized (26 DES vs. 27 DCB). At 90 days, both strategies showed a low rate of uncovered struts (3.2 vs. 3.2%, P = 0.64) and a very high and similar rate of covered and apposed struts (96.6 vs. 96.1%, respectively; P = 0.58). However, DCB group had a significantly lower rate of major coronary evaginations (68 vs. 37%, P = 0.026), and more frequently developed a thin homogeneous neointimal layer (20 vs. 70.4%, P = 0.001) suggesting distinct superior healing at 3 months compared to DES.

CONCLUSIONS

In pPCI both, sirolimus-DES and DCB-strategy, provide excellent strut coverage at 3 months. However, DCB ensures more advanced and optimal stent healing compared to sirolimus-DES. Further research is needed to determine whether, in patients undergoing pPCI, DCB offers superior long-term clinical and angiographic outcomes than new-generation DES (NCT03610347).

Impact of optical coherence tomography-derived neointimal tissue morphology on development of very late in-stent restenosis

OBJECTIVES

This study evaluated the progression of very late in-stent restenosis (VL-ISR) by analyzing four serial coronary angiography (CAG) images and its correlation with neointimal tissue characterization of the VL-ISR lesions on optical coherence tomography (OCT).

BACKGROUND

Recently, VL-ISR is occasionally observed beyond a few years after drug-eluting stents (DESs) implantation.

METHODS

This study analyzed 50 VL-ISR lesions after DES in which 4 serial CAGs over a period of 2 years, including at baseline procedure, 9 months after baseline procedure, 12 months before VL-ISR, and at the time of VL-ISR, were performed. Neointimal tissue characteristics by OCT were categorized as homogeneous, heterogeneous with invisible strut (Type I), heterogeneous with visible strut (Type II), speckled (Type III), or heterogeneous with sharply delineated border (Type IV).

RESULTS

From the development process, 23 VL-ISRs (46%) were categorized as rapid progression and 27 (54%) as gradual progression. The five categories of neointimal tissue composition significantly differed between lesions with rapid and gradual progression. Homogeneous neointima and Type IV heterogeneous neointima were observed only in lesions with gradual progression. Moreover, most Type I heterogeneous neointima was identified in lesions with gradual progression. Instead, main neointimal tissue components of lesions with rapid progression were Type II (43%) and Type III (43%) heterogeneous neointima.

CONCLUSION

The progression rate of in-stent atherosclerotic changes is gradual, whereas organized thrombus could be associated with an increased risk of rapid neointimal growth. The two types of stenosis progression provide a new insight into the mechanism of VL-ISR development after DES implantation.

Neointima characteristics as a prognostic marker for drug-coated balloon angioplasty in patients with in-stent restenosis: an optical coherence tomography study

BACKGROUND

Research has shown that the prognosis of in-stent restenosis (ISR) lesions after drug-coated balloon (DCB) angioplasty can differ in relation to in-stent neointimal characteristics. However, changes in neointima characteristics after DCB have not been studied. This study sought to investigate changes in neointima characteristics after DCB for ISR.

METHODS

From the Yonsei Optical Coherence Tomography (OCT) registry, data on DCBs performed in patients with ISR were collected. Neointima characteristics were categorized as homogeneous, heterogeneous, layered neointima, and neoatherosclerosis in each OCT procedure. Homogeneous and layered neointima were classified as a favorable neointima, while heterogeneous neointima and neoatherosclerosis were classified as an unfavorable neointima. The data of 67 ISR patients were analyzed.

RESULTS

The median duration between initial and follow-up OCT was 9.6 months. Patients with homogeneous and layered neointima on the initial OCT before DCB mostly appeared as homogeneous (66.7 and 68.2%, respectively) on the follow-up OCT, whereas most of the patients with heterogeneous neointima on the initial OCT remained unaltered (70%). Patients with unfavorable neointima at either the initial (P = 0.023) or the follow-up OCT (P = 0.037) had a worse major adverse cardiovascular event-free survival than the other patients. Patients who showed unfavorable neointima at both the initial and the follow-up OCT had the worst event-free survival (P = 0.038).

CONCLUSIONS

The follow-up OCT neointimal characteristics after DCB for ISR was associated with initial OCT characteristics. Sustained unfavorable neointima in serial OCT imaging may reflect poor prognosis in patients with ISR treated with DCB.

Comparison of post-stent irregular protrusion and subsequent neointimal characteristics between second- and third-generation drug-eluting stent implantation

BACKGROUND

Third-generation drug-eluting-stents (3rd DES) may improve coronary arterial healing and reduce neoatherosclerosis formation. We evaluated post-stent findings and subsequent vascular healing of 3rd DES by comparing to second-generation drug-eluting-stents (2nd DES) at intermediate-term follow-up using optical coherence tomography (OCT).

METHOD

We evaluated 170 patients with 170 lesions who underwent DES implantation (2nd DES, n = 98; 3rd DES, n = 72) and OCT-guided follow-up examination. After propensity score (PS) matching for baseline clinical characteristics, OCT findings from 56 pairs of patients with 2nd DES and 3rd DES implants were compared. Post-stent irregular protrusion (IP) was defined as the protrusion of material with an irregular surface into the lumen between the stent struts. Neoatheroscleosis was defined as neointima contained heterogeneous pattern, rupture, lipid-laden, thin-cap fibroatheroma, or calcification. The presence of peri-strut low-intensity area (PLIA) and in-stent neointimal tissue characteristics were also analyzed at 6- to 8-month follow-up.

RESULTS

There were no significant differences between the incidence of post-stent IP or neoatherosclerosis formation in the 2nd DES and the 3rd DES (45% vs. 38%, p = 0.44; 30% vs. 20%, p = 0.19, respectively). However, the incidences of PLIA and layered neointimal pattern, which indicate immature neointimal healing, were significantly lower in the 3rd DES compared to the 2nd DES (41% vs. 61%, p = 0.04; 2% vs. 11%, p = 0.04, respectively). As comparing intermediate-term follow-up OCT neointimal findings in patients with IP between 2nd DES and 3rd DES, most neointima tended to have a homogeneous pattern (95% versus 76%, p = 0.06) in the 3rd DES than in the 2nd DES.

CONCLUSIONS

The incidence of post-stent IP and subsequent neoatherosclerosis formation at intermediate-term follow-up after stent implantation were similar between patients with 2nd DES and 3rd DES, however, vascular healing might be favorable when using 3rd DES.

Repetitive restenosis in a biodegradable polymer sirolimus-eluting stent with hypersensitivity reaction: a case report

Background 

Hypersensitivity reaction is a classic cause of in-stent restenosis (ISR) in coronary stents, typically reported in bare-metal stents and first-generation drug-eluting stents. Biodegradable polymer sirolimus-eluting stent (BP-SES) was developed with the concept of biocompatibility, and there has been no report of ISR of BP-SES with hypersensitivity reaction.

Case summary 

An 81-year-old woman presented with ST-elevation acute inferior myocardial infarction. Primary percutaneous coronary intervention was performed for the culprit lesion in the left circumflex artery with a permanent polymer everolimus-eluting stent (PP-EES), followed by BP-SES implantation in the left anterior descending artery. Eight months later, coronary angiography showed total occlusion of the PP-EES and diffuse ISR in the BP-SES, treated with a paclitaxel-eluting balloon. Fluorodeoxyglucose with positron emission tomography showed increased uptake around the BP-SES, and cardiac magnetic resonance imaging revealed a late gadolinium-enhanced area around both stents. Four months later, she developed re-ISR in the BP-SES, and optical coherence tomography demonstrated diffuse-layered neointimal hyperplasia with microvascularization and peri-strut low-intensity area. She was successfully treated with coronary artery bypass grafting.

Discussion 

Our case demonstrated repetitive short-term ISR of the BP-SES. Observation by both intravascular and non-invasive imaging modalities suggested the presence of hypersensitivity reaction localized in the stent. Hypersensitivity to the metal may be a possible mechanism because both stents are composed of L605 cobalt-chromium alloy. This is the first report of ISR of a BP-SES with hypersensitivity reaction. Non-invasive imaging can be useful to assess this critical condition.

Short-term stent coverage of second-generation zotarolimus-eluting durable polymer stents: Onyx one-month optical coherence tomography study

Introduction

To date the early strut coverage with the second-generation durable-polymer ONYX zotarolimus-eluting stent (O-ZES) is unknown.

Aim

Optical coherence tomography (OCT) assessed the strut coverage of O-ZES at thirty-day follow-up.

Material and methods

OCT was performed after implantation and at 1-month follow-up in 15 patients treated with O-ZES.

Results

Mean patient age was 67 ±7 years (73% males). The clinical presentation consisted of acute coronary syndromes (n = 13) and stable coronary disease (n = 2). Four (26%) patients had diabetes. OCT analysis was performed at baseline and 1-month follow-up in all stents. 378 cross-sections with 3582 struts were assessed at baseline and 3661 at follow-up. At follow-up, 88% struts were covered by tissue with a median thickness 37.91 μm (IQR: 22.32–64.15). Median in-stent area obstruction by neointima was 2.64% (IQR: 1.70–4.84). From the total stent covered area, 92.3% showed complete strut coverage. Homogeneous tissue was observed in 74% of cases. There were no differences in minimal lumen area (5.07 ±1.08 mm² vs. 4.81 ±0.94 mm², p = 0.125) or minimal stent area (4.95 ±1.22 mm² vs. 4.92 ±0.99 mm²) at baseline and at follow-up. There were no differences in the rate of strut malapposition (4.3% vs. 5.7%, p = 0.417). For all stents, malapposition volume was 47.9 mm³ at baseline and 51.7 mm³ at follow-up, giving the late acquired stent malapposition volume of 3.8 mm³.

Conclusions

The second-generation durable polymer O-ZES showed favorable vessel healing at 30-day OCT follow-up.

Blood Cell Parameters and Predicting Coronary In-Stent Restenosis

Major advances in coronary interventional techniques and pharmacotherapy as well as the use of drug-eluting stents (DESs) have considerably reduced the risk of in-stent restenosis (ISR). However, ISR remains a major clinical challenge. Inflammation and platelet activation are important processes that underlie the pathophysiology of ISR. Parameters related to blood cells, entailing both cell count and morphology, are useful markers of the inflammatory response and platelet activation in clinical practice. Recent studies have highlighted several new combined or derived parameters related to blood cells that independently predict ISR after DES implantation. The neutrophil/lymphocyte ratio, an inflammatory marker, is regarded as a predictor of the risk of ISR and the stability of atherosclerotic plaques. The mean platelet volume, a widely used platelet activation parameter, has been shown to be a predictor of the risk of ISR and the efficacy of antiplatelet therapy. Other markers considered include the platelet/lymphocyte ratio, red blood cell distribution width, and platelet distribution width. This review provides an overview of these parameters that may help stratify the risk of coronary angiographic and clinical outcomes related to ISR.

Prediction models for different plaque morphology in non-significantly stenosed regions of saphenous vein grafts assessed with optical coherence tomography

Introduction

Coronary artery bypass grafting (CABG) is a method of choice in treatment of diffuse coronary artery disease (CAD), although it has some limitations such as late saphenous vein graft (SVG) patency loss, which occurs in one fifth of all conduits at 5 years. Since atherosclerosis in SVG has diffuse characteristics, it appears that significantly and non-significantly stenosed lesions may have an equal impact on worse prognosis.

Aim

To assess non-significant lesions of SVG by the use of optical coherence tomography (OCT) and investigate the clinical and laboratory findings with the potential impact on plaque composition.

Material and methods

Twenty-nine patients with 43 non-significant lesions were enrolled in the study. All variables were assessed using uni- and multivariable logistic regression analysis with each plaque morphology as a dependent variable. Odds ratio (OR) and 95% confidence interval (CI) were computed.

Results

Plaque rupture (PRT) was independently associated with age (OR = 1.49, 95% CI: 1.09–2.04, p = 0.015) and lower rates of high-density lipoproteins (HDL) cholesterol (OR = 0.67, 95% CI: 0.49–0.92, p = 0.016). Intimal tearing or rupture (ITR) was related to reduced GFR (OR = 0.52, 95% CI: 0.38–0.72, p = 0.0004). Lipid-rich plaque (LRP) was associated with raised platelet count (PLT) (OR = 1.51, 95% CI: 1.16–1.96, p = 0.004) and increased frequency of smoking (OR = 1.45, 95% CI: 1.12–1.89, p = 0.007).

Conclusions

Atherosclerosis of SVG is not restricted to significantly stenosed lesions. Plaque composition is independently associated with different types of clinical and laboratory findings, mostly recognized as risk factors of CAD.

Association Between TG-to-HDL-C Ratio and In-Stent Stenosis Under Optical Coherence Tomography Guidance

We determined the relevance between the TG-to-HDL-C ratio and stent restenosis. Ninety-nine patients with in-stent stenosis (ISR) who were admitted to An Zhen Hospital in Beijing between April 2014 and June 2017 were selected. At the same time, 122 patients with coronary stenosis <50% were selected. All patients were tested for TG, HDL-C, and TG/HDL-C ratio. Optical coherence tomography (OCT) can assess microscopic status in all ISR patients. The proportion of male and Diabetic patients were significantly higher for ISR. There were differences in the prevalence of cigarette smokers among the different tissue types, among which the layered tissue type accounted for the highest proportion. In logistic regression analysis the study showed that male, diabetes mellitus, and the TG/HDL-C ratio are risk factors for ISR. The ISR ROC was 0.725 based on the TG/HDL-C ratio diagnosis. It is related to the degree of coronary stenosis and effective in diagnosing in-stent stenosis in ISR.

Correlation between pre-procedural plaque morphology and patterns of in-stent neointimal hyperplasia at 1-year follow-up in patients treated with new-generation drug-eluting stents: An optical coherence tomography based analysis

INSTRUCTION

Several factors affect the in-stent intimal healing process after drug-eluting stents (DESs) implantation. We hope to investigate the influence of plaque characteristics on subsequent heterogeneous neointimal hyperplasia (NIH) using optical coherence tomography (OCT).

METHODS

The study population consisted 217 patients with single-vessel de novo lesions who underwent both pre-procedural OCT scan and 12-month follow-up OCT examination. NIH is defined as at least five consecutive cross-sectional images with no less than 100µm neointimal thickness. According to OCT follow-up, patients were divided into three groups: neointima-covered group, homogeneous, and heterogeneous NIH group.

RESULTS

102 patients were categorized in neointima-covered group, 91 and 24 patients in homogeneous and heterogeneous group, respectively. Time interval between OCT scans was similar (P = 0.55). No significant differences in the patients' age, gender, comorbidities, laboratory findings, procedural, and lesion-related findings were found among these three groups. Heterogeneous group tended to have more subjects presented as acute coronary syndrome (ACS) (P = 0.04) and mean macrophage grade was higher in this group (P = 0.01). While no statistically significant difference concerning mean intimal thickness (P = 0.21) or neointimal burden (P = 0.73) was found between homogeneous and heterogeneous group. Multivariate logistic regression analysis showed that mean macrophage grade (OR: 2.26, 95%CI: 1.12 to 4.53, P = 0.02) and initial clinical presentation of ACS (OR: 2.81, 95%CI: 1.03 to 7.72, P = 0.04) were significant independent risk factors for heterogeneous NIH.

CONCLUSION

Mean macrophage grade measured by OCT as a semi-quantitative morphological risk factor, as well as clinical presentation of ACS, was associated with in-stent neointimal heterogeneity after DES implantation.

An optical coherence tomography study of neointimal morphology and strut coverage at different time intervals from implantation of biodegradable polymer-coated sirolimus-eluting stents

OBJECTIVES

The aim of the study was to capture the evolution of neointima after implantation of a biodegradable polymer-coated, sirolimus-eluting, cobalt-chromium coronary stent system (BP-DES).

BACKGROUND

Optical coherence tomography (OCT) suggests that in-stent neointimal morphology influences clinical outcomes after DES implantation.

METHODS

Sixty patients treated with single BP-DES implantation were examined by quantitative coronary angiography (QCA) and OCT at 3, 6, and 12-month follow-up.

RESULTS

Median late lumen loss by QCA (mm) was 0.04 (IQR 0, 0.08), 0.17 (IQR 0, 0.32), and 0.14 (IQR 0.07, 0.31) at 3, 6, and 12-month follow-up respectively (P = 0.03). OCT cross-section multilevel analysis showed uncovered struts in 3.90%, 1.78%, and 0.02% of struts respectively (P = 0.03). The corresponding malapposition rates were 0.12%, 0.04%, and 0%. Lipid-rich neointima was observed only at 12-month follow-up in one restenotic lesion (0.77% cross-sections) that was accountable for the only target vessel revascularization. The homogeneous pattern was prevalent at all three time points, but its incidence displayed an upward trend (3 months: 59%; 6 months: 71%; 12 months: 88%) despite no difference in neointimal volume between 6 and 12 months. Conversely, a trend could be observed of decreasing incidence of heterogeneous pattern as the follow-up length increased.

CONCLUSIONS

In this study of a single-type BP-DES, the majority of stent struts were covered within 3 months from implantation. While the quantitative neointimal accumulation plateaued at 6 months with no further significant increase beyond 6 months, the neointima continued to evolve qualitatively and mature along with better strut coverage between 6 and 12 months after implantation.

Saphenous graft atherosclerosis as assessed by optical coherence tomography data for stenotic and non-stenotic lesions from the OCTOPUS registry

Introduction

Coronary artery bypass grafting (CABG), although widely used for a long time in diffuse coronary artery disease (CAD), has serious limitations associated with graft aging and its degeneration.

Aim

The relationship between saphenous vein graft (SVG) plaque morphology assessed by optical coherence tomography (OCT) and clinical findings has not been elucidated yet.

Material and methods

We compared the morphology of SVG in stenotic vs. non-stenotic lesions using OCT imaging in 29 patients hospitalized in our center within the OCTOPUS registry.

Results

Stenotic lesions were characterized by higher incidence of thin-cap fibroatheroma (TCFA) (33% vs. 0%, p = 0.0048), thrombus (28% vs. 0%, p = 0.0008), lipid-rich plaque (LRP) (75% vs. 35%, p = 0.0013) and plaque within the SVG valve (19% vs. 0%, p = 0.0114) as compared to non-stenotic lesions. Patients with intimal tearing or rupture (ITR) were older (75.8% vs. 68.9 years, p = 0.047) and had lower left ventricular ejection fraction (LVEF) (32.0% vs. 49.7%, p = 0.001) and glomerular filtration rate (GFR) (36.0 vs. 73.6 ml/min/1.73 m², p = 0.010). Patients with calcified lesions vs. those without had lower high-density lipoprotein (HDL) cholesterol (33.2 vs. 44.1 mg/dl, p = 0.018), similarly to those with ruptured plaque vs. those without (28.3 vs. 41.7 mg/dl, p = 0.047).

Conclusions

Presence of ITR was associated with advanced age, decreased LVEF and renal insufficiency. Decreased concentration of HDL was associated with higher occurrence of calcified and ruptured plaque.

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.

Macrophage polarization and acceleration of atherosclerotic plaques in a swine model

Aims

Atherosclerosis is a well-known cause of cardiovascular disease and is associated with a variety of inflammatory reactions. However, an adequate large-animal model of advanced plaques to investigate the pathophysiology of atherosclerosis is lacking. Therefore, we developed and assessed a swine model of advanced atherosclerotic plaques with macrophage polarization.

Methods

Mini-pigs were fed a 2% high-cholesterol diet for 7 weeks followed by withdrawal periods of 4 weeks. Endothelial denudation was performed using a balloon catheter on 32 coronary and femoral arteries of 8 mini-pigs. Inflammatory proteins (high-mobility group box 1 [HMGB1] or tumor necrosis factor alpha (TNF-α) were injected via a micro-infusion catheter into the vessel wall. All lesions were assessed with angiography and optical coherence tomography and all tissues were harvested for histological evaluation.

Results

Intima/plaque area was significantly higher in the HMGB1- and TNF-α-injected groups compared to the saline-injected group (p = 0.002). CD68 antibody detection and polarization of M1 macrophages significantly increased in the inflammatory protein-injected groups (p<0.001). In addition, advanced atherosclerotic plaques were observed more in the inflammatory protein-injected groups compared with the control upon histologic evaluation.

Conclusion

Direct injection of inflammatory proteins was associated with acceleration of atherosclerotic plaque formation with M1 macrophage polarization. Therefore, direct delivery of inflammatory proteins may induce a pro-inflammatory response, providing a possible strategy for development of an advanced atherosclerotic large-animal model in a relatively short time period.

Prognostic Value of Type D Personality for In-stent Restenosis in Coronary Artery Disease Patients Treated With Drug-Eluting Stent

OBJECTIVE

To evaluate the predictive value of Type D personality on in-stent restenosis (ISR) rates at 1 and 2 years post-percutaneous coronary intervention (PCI) in patients with coronary artery disease.

METHODS

Consecutive patients with coronary artery disease who underwent PCI for drug-eluting stents (n = 173) completed the Type D Scale-14 (DS14) at baseline. Follow-up coronary angiographic evaluation was routinely planned at 1 and 2 years after the procedure.

RESULTS

Follow-up coronary angiography was performed in 159 and 112 patients at 1 and 2 years post-PCI, respectively. On multivariate analysis, Type D personality was found to be an independent predictor of ISR at 1 year (odds ratio [OR] = 2.67, 95% confidence interval [CI] = 1.16-6.14, p = .021) and 2 years (OR = 4.92, 95% CI = 1.82-9.60, p = .017) after adjusting for cardiovascular risk factors. However, Type D did not predict ISR when the analysis was performed using the interaction between negative affectivity and social inhibition. The main effect of negative affectivity emerged as a significant risk factor for 1-years (OR = 4.22, 95% CI = 1.18-7.86, p = .034) and 2-year ISR (OR = 6.93, 95% CI = 2.25-11.50, p = .016).

CONCLUSIONS

In this study, Type D personality was an independent predictor of ISR at 1 and 2 years post-PCI; the association strengthened with time. The negative affectivity component seems to drive the relationship between Type D and ISR over time. Our findings provide new insights into the mechanisms involved in the association between Type D and adverse clinical outcomes of PCI.

Comparative assessment of three drug eluting stents with different platforms but with the same biodegradable polymer and the drug based on quantitative coronary angiography and optical coherence tomography at 12-month follow-up

The aim of this study was to compare neointima proliferation in three drug-eluting stents (DES) produced by the same company (Balton, Poland) which are covered with a biodegradable polymer and elute sirolimus (concentration: 1.0 and 1.2 µg/mm²), but have different stent platforms and strut thickness: stainless steel Prolim^® (115 µm) and BiOSS LIM^® (120 µm) and cobalt-chromium Alex^® (70 µm). We analyzed data of patients with quantitative coronary angiography (QCA) and optical coherence tomography (OCT) at 12 months from BiOSS LIM Registry, Prolim Registry and Alex OCT clinical trial. There were 56 patients enrolled, in whom 29 Prolim^® stents were deployed, in 11-BiOSS LIM^® and in 16-Alex stents. The late lumen loss was the smallest in Prolim^® subgroup (0.26 ± 0.17 mm) and did not differ from Alex^® subgroup (0.28 ± 0.47 mm). This parameter was significantly bigger in BiOSS^® subgroup (0.38 ± 0.19 mm; p < 0.05). In OCT analysis there was no statistically significant difference between Prolim^® and Alex^® subgroups in terms of mean neointima burden (24.6 ± 8.6 vs. 19.27 ± 8.11%) and neointima volume (28.16 ± 15.10 vs. 24.51 ± 17.64 mm³). In BiOSS^® group mean neointima burden (30.9 ± 6.2%) and mean neointima volume (44.9 ± 4.9 mm³) were significantly larger. The morphological analysis revealed that in most cases in all groups the neointima was homogenous with plaque presence only around stent struts. In the QCA and OCT analysis regular DES (Prolim^® and Alex^®) obtained similar results, whereas more pronounced response from the vessel wall was found in the BiOSS^® subgroup.

Dynamic neointimal pattern after drug-eluting stent implantation defined by optical coherence tomography

OBJECTIVES

Certain neointimal patterns including neoatherosclerosis (NA) are known to be associated with poor clinical outcome. The prevalence and time course of different neointimal patterns have not been studied systematically. The aim of this study was to investigate the serial changes in neointimal pattern after drug-eluting stent implantation.

PATIENTS AND METHODS

A total of 132 patients with 207 drug-eluting stents, who underwent two follow-up optical coherence tomography studies at 6 and 12 months, were included. Neointimal patterns were categorized as homogeneous, heterogeneous, layered, or NA using optical coherence tomography. Quantitative and qualitative analyses of neointima were carried out.

RESULTS

Both at 6 and at 12 months, the homogenous neointima was the predominant type (>75%), followed by the layered and the heterogeneous pattern. At 12 months, progression to NA was observed in 0.6% of the patients in the homogeneous group, in 5.6% of the patients in the heterogeneous group, and in 3.9% of the patients in the layered group. Regression to the homogeneous pattern was observed in 5.6% of the patients in the heterogeneous group and 11.5% of the patients in the layered group.

CONCLUSION

The homogenous neointima is the predominant pattern both at 6 and at 12 months. The neointimal pattern changed between 6 and 12 months in 10.6% of stents. Further studies are needed to understand the mechanisms of these neointimal changes and their clinical significance.

Development of Advanced Atherosclerotic Plaque by Injection of Inflammatory Proteins in a Rabbit Iliac Artery Model

PURPOSE

Appropriate animal models of atherosclerotic plaque are crucial to investigating the pathophysiology of atherosclerosis, as well as for the evaluation of the efficacy and safety of vascular devices. We aimed to develop a novel animal model that would be suitable for the study of advanced atherosclerotic lesions in vivo.

MATERIALS AND METHODS

Atherosclerotic plaque was induced in 24 iliac arteries from 12 rabbits by combining a high cholesterol diet, endothelial denudation, and injection into the vessel wall with either saline (n=5), olive oil (n=6), or inflammatory proteins [n=13, high-mobility group protein B1 (HMGB1) n=8 and tumor necrosis factor (TNF)-α n=5] using a Cricket™ Micro-infusion catheter. Optical coherence tomography (OCT) was performed to detect plaque characteristics after 4 weeks, and all tissues were harvested for histological evaluation.

RESULTS

Advanced plaque was more frequently observed in the group injected with inflammatory proteins. Macrophage infiltration was present to a higher degree in the HMGB1 and TNF-α groups, compared to the oil or saline group (82.1±5.1% and 94.6±2.2% compared to 49.6±14.0% and 46.5±9.6%, p-value<0.001), using RAM11 antibody staining. On OCT, lipid rich plaques were more frequently detected in the inflammatory protein group [saline group: 2/5 (40%), oil group: 3/5 (50%), HMGB1 group: 6/8 (75%), and TNF-α group: 5/5 (100%)].

CONCLUSION

These data indicate that this rabbit model of atherosclerotic lesion formation via direct injection of pro-inflammatory proteins into the vessel wall is useful for in vivo studies investigating atherosclerosis.

Optical Coherence Tomography of De Novo Lesions and In-Stent Restenosis in Coronary Saphenous Vein Grafts (OCTOPUS Study)

BACKGROUND

The OCTOPUS registry prospectively evaluates the procedural and long-term outcomes of saphenous vein graft (SVG) PCI. The current study assessed the morphology of de novo lesions and in-stent restenosis (ISR) in patients undergoing PCI of SVG.

METHODS AND RESULTS

Optical coherence tomography (OCT) of SVG lesions in consecutive patients presenting with stable CAD and ACS was carried out. Thirty-nine patients (32 de novo and 10 ISR lesions) were included in the registry. ISR occurred in 5 BMS and 5 DES. There were no differences in the presence of plaque rupture and thrombus between de novo lesions and ISR. Lipid-rich tissue was identified in both de novo lesions and in ISR (75% vs. 50%, P=0.071) with a higher prevalence in BMS than in DES (23% vs. 7.5%; P=0.048). Calcific de novo lesions were detected in older grafts as compared with non-calcific atheromas (159±57 vs. 90±62 months after CABG, P=0.001). Heterogeneous neointima was found only in ISR (70% vs. 0, P<0.001) and was observed with similar frequency in both BMS and DES (24% vs. 30%, P=0.657). ISR was detected earlier in DES than BMS (median, 50 months; IQR, 18-96 months vs. 27 months; IQR, 13-29 months, P<0.001).

CONCLUSIONS

OCT-based characteristics of de novo and ISR lesions in SVG were similar except for heterogeneous tissue, which was observed only in ISR. (Circ J 2016; 80: 1804-1811).

Role of red blood cell distribution in predicting drug-eluting stent restenosis in patients with stable angina pectoris after coronary stenting

BACKGROUND

It has been reported that increased red blood cell distribution width (RDW) predicts adverse events in cardiovascular disease and in patients undergoing percutaneous coronary intervention. However, the role of serum RDW levels in drug-eluting stent (DES) restenosis remains unclear. We aimed to investigate the relationship between serum RDW levels and in-stent restenosis (ISR) after coronary stenting with DES in stable angina pectoris (SAP) patients.

MATERIALS AND METHODS

A total of 293 consecutive chronic SAP patients with coronary DES implantation were enrolled in this study. The ISR was analyzed by coronary angiography analysis at a mean follow-up of 8 months. According to whether ISR was detected, patients were divided into two groups: the ISR group (n=45) and the non-ISR group (n=247). Serum RDW was assessed both at admission and at the 8-month follow-up in all patients. Standard medication was continued throughout the investigation period.

RESULTS

Baseline characteristics of the two groups were similar. Patients in the ISR group had significantly higher RDW levels compared with patients in the non-ISR group both at admission and at follow-up (P<0.01, respectively). Furthermore, the ISR group had significantly longer stent length and lower stent diameter compared with the non-ISR group (P<0.01, respectively). In a multivariate analysis, diabetes mellitus, current smoking, RDW levels, C-reactive protein levels, stent length, and stent diameter were associated independently with ISR.

CONCLUSION

Serum RDW level may independently predict ISR at both admission and follow-up in SAP patients with coronary DES implantation, which indicates that a chronic inflammatory response might be involved in the pathogenesis of ISR.

Novel sirolimus-eluting stent Prolim® with a biodegradable polymer in the all-comers population: one year clinical results with quantitative coronary angiography and optical coherence tomography analysis

BACKGROUND

The aim of this study was to assess the safety and the efficacy of the novel sirolimus-eluting Prolim® stent with a biodegradable polymer in the all-comers population.

METHODS

We prospectively enrolled all patients with stable coronary artery disease or acute coronary syndrome treated with Prolim® stent between January and December 2013 in two interventional cardiology centers in Poland. Angiographic control was planned at 12 months, in which 15 % of patients (randomly chosen) underwent optical coherence tomography imaging. The primary end-point was the cumulative rate of cardiac death, myocardial infarction, and target lesion revascularization at 12 months.

RESULTS

There were 204 patients enrolled, in whom 238 Prolim® stents were deployed (1.17 stent per patient). The mean age was 68 ± 10 years and 32.8 % were females. The examined stent was implanted in 5.9 % in STEMI patients, in 21.6 % - in NSTE-ACS and in 72.5 % - in patients with stable coronary artery disease. The Prolim® stent was most frequently implanted in right coronary artery (38.2 %) followed by left anterior descending artery (34.0 %). The cumulative major adverse cardiovascular events rate at 12 months was 6.9 %, and the clinically-driven target lesion revascularization rate - 5.4 %. At 12 months in quantitative coronary angiography the late lumen loss was 0.21 ± 0.18 mm, and in optical coherence tomography the mean neointima burden was 24.6 ± 8.6 %.

CONCLUSIONS

Sirolimus-eluting Prolim® stent with a biodegradable polymer is a feasible device with a very good safety profile and long-term clinical effectiveness.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02545985 .

Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

PURPOSE

Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~10-15 μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs).

METHODS

Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6 months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3 months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts.

RESULTS

The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1%±1.4% and 0.5%±3.2%. Interobserver variability also proved to be low: -2.1%±3.3% and 2.1%±4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02%±6.8% and -0.18%±5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ)=0.91 (95% confidence interval (CI): 0.88-0.93, p<0.01), κ=0.88 (95% CI: 0.85-0.91, p<0.01), and κ=0.73 (95% CI: 0.68-0.78, p<0.01), respectively.

CONCLUSIONS

FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage.

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.

Neointimal Coverage After Drug-Eluting Stent Implantation: Insights from Optical Coherence Tomography

Optical coherence tomography (OCT), which provides high-resolution imaging of the coronary vasculature, has provided novel insights into the pathophysiology of neointimal growth after drug-eluting stent (DES) implantation. The natural history, time course, and characteristics of strut coverage with neointima have been well defined by OCT. Pathology studies have identified strut coverage as a risk factor for stent thrombosis, and OCT studies have shown that next-generation DES have better strut coverage than first-generation DES. By reducing the incidence of stent thrombosis, improved strut coverage should lead to favorable clinical safety and the feasibility of shorter-duration dual antiplatelet therapy after DES implantation.

Serial changes of neointimal tissue after everolimus-eluting stent implantation in porcine coronary artery: an optical coherence tomography analysis

Purposes. The serial changes in neointimal tissues were compared between everolimus-eluting stent (EES) and bare-metal stent (BMS) in the porcine coronary artery using optical coherence tomography (OCT). Methods. Serial (1, 3, and 6 month follow-up after stent implantation) OCT examinations were performed in 15 swine with 15 BMS- and 15 EES-treated lesions in porcine coronary arteries. Results. In BMS-implanted lesions, neointimal volume decreased from 7.3 mm³ to 6.9 mm³ and 6.4 mm³ at 1, 3, and 6 months follow-up without statistical significance (P = 0.369). At the time points of 1, 3, and 6 months, neointimal tissue appearance was mainly a homogeneous pattern (80.0%, 93.3%, and 100%, resp.), while the other pattern was layered. In contrast, in EES-implanted lesions, neointimal volume significantly increased from 4.8 mm³ to 9.8 mm³ between 1 and 3 months but significantly decreased to 8.6 mm³ between 3 and 6 months (P < 0.001). Between 1 and 3 months, the layered pattern of neointimal tissue increased from 26.7% to 66.7% but decreased to 20.0% between 3 and 6 months. Conclusions. EES had a biphasic pattern of neointimal amounts that correlated with changes in neointimal morphology.

Long-term outcomes of neointimal hyperplasia without neoatherosclerosis after drug-eluting stent implantation

OBJECTIVES

The aim of this study was to investigate the correlation between in-stent neointimal tissue without features of neoatherosclerosis and long-term clinical outcomes.

BACKGROUND

Recent studies have reported differential morphological characteristics of in-stent neointimal tissue assessed by optical coherence tomography (OCT).

METHODS

The study population consisted of 336 patients with 368 drug-eluting stent-treated lesions. Patients received a follow-up OCT examination without any intervention. OCT-based neointima was categorized as homogeneous (n = 227 lesions in 208 patients), heterogeneous (n = 79 lesions in 73 patients), or layered (n = 62 lesions in 55 patients). Major adverse cardiac events (MACE) (a composite of cardiac death, nonfatal myocardial infarction, or target lesion revascularization) were assessed according to neointimal patterns during long-term clinical follow-up after OCT examination.

RESULTS

The time interval between stent implantation and OCT examination was similar among the 3 groups (p = 0.64). On multivariate logistic regression analysis, the significant determinant for the heterogeneous neointima was age (odds ratio [OR]: 1.037, 95% confidence interval [CI]: 1.007 to 1.068, p = 0.015) and an initial clinical presentation of acute coronary syndrome (OR: 1.967, 95% CI: 1.159 to 3.339, p = 0.012). The overall median follow-up duration for all patients after follow-up OCT examination was 31.0 months, and this was statistically different among the heterogeneous group (22.0 months), the homogeneous group (34.0 months), and the layered group (28.0 months, overall p = 0.002). MACE occurred more frequently in patients with heterogeneous neointima over a median 31-month follow-up period after OCT examination (13.7% vs. 2.9% in homogeneous vs. 7.3% in layered, p = 0.001). A propensity score-adjusted Cox regression analysis showed that independent risk factors for MACE were inclusion in the heterogeneous neointima (hazard ratio: 3.925, 95% CI: 1.445 to 10.662, p = 0.007) and minimal lumen cross-sectional area (hazard ratio: 0.368, 95% CI: 0.242 to 0.560, p < 0.001).

CONCLUSIONS

Determination of neointimal characteristics is helpful in predicting long-term clinical outcomes. Our data suggest that heterogeneous lesions are linked to poor long-term clinical prognoses.