Neointimal tissue characteristics following sirolimus-eluting stent implantation: OCT quantitative tissue property analysis

Methotrexate Therapy Promotes Cell Coverage and Stability in in-Stent Neointima

PURPOSE

Anti-proliferative drugs released from drug-eluting stents delay cell coverage and vascular healing, which increases the risk of late stent thrombosis. We assessed the potential effects of systemic methotrexate (MTX) on cell coverage, vascular healing and inflammation activation in vivo and in vitro.

METHODS

We applied MTX in the right common carotid artery in a rabbit stenting model to determine the impact on cell coverage and inflammation activation using a serial optical coherence tomography (OCT) analysis and elucidated the molecular mechanism of MTX in human umbilical vein endothelial cells (HUVECs).

RESULTS

Low-dose MTX promoted the development of cell coverage and vascular healing, which was associated with fewer uncovered struts (%) and cross-sections with any uncovered struts (%) at 4 weeks of stenting. The MTX group also exhibited lower rates of heterogeneity, microvessels and per-strut low-signal-intensity layers, indicating neointimal instability at 12 weeks of stenting. In vitro, low-dose MTX strongly inhibited HUVEC apoptosis, promoted proliferation and inhibited inflammatory activation by targeting the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway.

CONCLUSION

Low-dose MTX may be a key means of promoting early cell coverage via the inhibition of the inflammatory response and stability of neointima by targeting inflammatory pathways after stent implantation.

A comparison of procedural success rate and long-term clinical outcomes between in-stent restenosis chronic total occlusion and de novo chronic total occlusion using multicenter registry data

Background

There have been little data about outcomes of percutaneous coronary intervention (PCI) for in-stent restenosis (ISR) chronic total occlusion (CTO) in the drug eluting stent (DES) era. This study aimed to compare the procedural success rate and long-term clinical outcomes of ISR CTO and de novo CTO.

Methods and results

Patients who underwent PCI for ISR CTO (n = 164) versus de novo CTO (n = 1208) were enrolled from three centers in Korea between January 2008 and December 2014. Among a total of ISR CTO, a proportion of DES ISR CTO was 79.3% (n = 130). The primary outcome was major adverse cardiac events (MACEs); a composite of all-cause death, non-fatal myocardial infarction (MI), or target lesion revascularization (TLR). Following propensity score-matching (1:3), the ISR CTO group (n = 156) had a higher success rate (84.6% vs. 76.0%, p = 0.035), mainly driven by high success rate of PCI for DES ISR CTO (88.6%), but showed a higher incidence of MACEs [hazard ratio (HR): 2.06; 95% confidence interval (CI) 1.37–3.09; p < 0.001], mainly driven by higher prevalence of MI [HR: 9.71; 95% CI 2.06–45.81; p = 0.004] and TLR [HR: 3.04; 95% CI 1.59–5.81; p = 0.001], during 5 years of follow-up after successful revascularization, as compared to the de novo CTO group (n = 408).

Conclusion

The procedural success rate was higher in the ISR CTO than the de novo CTO, especially in DES ISR CTO. However, irrespective of successful revascularization, the long-term clinical outcomes for the ISR CTO were significantly worse than those for the de novo CTO, in terms of MI and TLR.

Graphic abstract

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.

Evaluation of the characterization of thrombi in vitro by optical coherence tomography

AIM

The purpose of this study was to provide a new assessable method of the optical coherence tomography (OCT) in characterization of thrombi with different concentrations of red blood cell (RBC).

METHODS AND RESULTS

A series of thrombus models were constructed by using human blood in vitro. The thrombi were made by using human blood with different concentration of RBC (from 1% to 35%). Then tip of an FD-OCT catheter was put on the top of the thrombus to scan. After OCT being performed, all the acquired images were processed by a newly developed software to analyze the RBC levels related thrombus characteristics including attenuation, backscattering and light penetration depth. The attenuation was correlated with RBC concentration up to 9%. However, no apparent change was observed in thrombus with RBC concentration range from 10% to 35%. The same trend was seen in backscattering and penetration depth.

CONCLUSIONS

FD-OCT is able to detect thrombus with different RBC concentrations up to 9%.

The clinical characteristics and prognosis of lesions with in-stent eccentric tissue proliferation and strong signal attenuation detected by optical coherence tomography

There are still some patients who require repeat revascularization despite of drug-eluting stent (DES) implantation. The present study aimed to investigate the relationship between optical coherence tomography (OCT) findings and recurring target lesion revascularization (TLR) after percutaneous coronary intervention (PCI) for in-stent restenosis (ISR). We reviewed 50 patients (54 coronary lesions) who underwent PCI for ISR, which included 25 DES-ISR lesions. The PCI strategy depended on the interventionalist's discretion, and DES implantation was performed for 38 (70 %) lesions. Tissue characteristics were assessed qualitatively and quantitatively using the frame showing maximal lumen narrowing (minimal lumen area). In qualitative analysis, OCT detected coexistence of eccentric tissue proliferation and strong signal attenuation (ESA). ESA was observed in six lesions (11 %) in five patients (10 %). Hemodialysis (80 vs. 20 %, p = 0.013) and DES-ISR (100 vs. 40 %, p = 0.0069) were significantly more frequent in ESA patients/lesions than in others. One-year follow-up revealed that re-TLR was more frequently performed for ESA lesions (83 vs. 8 %, p = 0.0002). The findings reveal that ESA detected in OCT images of ISR is related to TLR after PCI for DES-ISR especially in patients undergoing maintenance hemodialysis.

In-stent neointimal characteristics and late neointimal response after drug-eluting stent implantation: A preliminary observation

BACKGROUND

Progressive neointimal proliferation may lead to late restenosis and/or neoatherosclerosis after drug-eluting stent (DES) implantation. Late neointimal response may be different among different tissue characteristics. The aim of this study was to assess impact of in-stent neointimal characteristics on late neointimal response following DES implantation.

METHODS

Serial (median 270 days and median 551 days after stent implantation) optical coherence tomography (OCT) examinations were performed in 42 stented lesions from 26 patients. In-stent neointimal tissue was categorized as either homogeneous or heterogeneous neointima based on the OCT appearance at 1st follow-up. Serial changes in neointimal area (NIA) were compared between lesions with homogeneous neointima and those with heterogeneous neointima.

RESULTS

At first follow-up, homogeneous neointima was observed in 22 (52%) and heterogeneous neointima in 20 (48%) lesions, respectively. During follow-up, NIA in lesions with homogeneous neointima decreased significantly (1.8±0.93 mm(2) to 1.5±0.88 mm(2), p<0.001). On the other hand, NIA in lesions with heterogeneous neointima did not change significantly (2.7±1.8 mm(2) to 2.8±1.6 mm(2), p=0.658). Homogeneous neointima was the only predictor of late neointimal regression (late neointimal regression defined as NIA at first follow-up - NIA at second follow-up <0) by multivariable analysis (odds ratio=7.591, 95% confidence interval: 1.616-35.67, p=0.010).

CONCLUSIONS

OCT characteristics of neointima after DES implantation may be related to late neointimal progression or regression.

Nonangiographic assessment of coronary artery disease: a practical approach to optical coherence tomography and fractional flow reserve

In an era of increased scrutiny of the appropriateness and safety of revascularization, interventional cardiologists must evolve by adding key tools to their armamentarium. This review highlights the utility of optical coherence tomography and fractional flow reserve in the catheterization lab and provides a practical guide for using these technologies during coronary intervention in various lesion subsets. We propose that fractional flow reserve informs the decision to intervene and optical coherence tomography guides the optimization of the outcome.

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.

Correlation between degree of neointimal hyperplasia and incidence and characteristics of neoatherosclerosis as assessed by optical coherence tomography

Emerging evidence suggests that neointimal degenerative changes with development of neoatherosclerosis (NA) may represent an important mechanism for late stent failure. The aim of the present study was to investigate the relation between degree of neointimal hyperplasia and incidence and characteristics of NA using optical coherence tomography. We identified a total of 252 stents with mean neointimal thickness (NIT) >100 μm in 212 patients: 100 bare metal stents (BMSs) and 152 drug-eluting stents (DESs). Based on the values of mean NIT, we divided stents into tertiles and compared neointimal characteristics among the 3 groups. NA was defined as the presence of lipid-laden intima and/or calcification inside the stent. In both BMS and DES, there was a difference in the prevalence of lipid-laden intima among the tertiles (18.2% vs 36.4% vs 47.1%, p = 0.042 [BMS]; 19.6% vs 56.9% vs 88.0%, p <0.001 [DES]). However, no difference in the prevalence of in-stent calcification was observed (21.2% vs 21.2% vs 2.9%, p = 0.053 [BMS]; 5.9% vs 9.8% vs 2.0%, p = 0.252 [DES]). In a multivariate model adjusting for stent type, follow-up duration, conventional coronary risk factors, statin, and angiotensin-converting enzyme inhibitor or angiotensin II receptor blockade use, mean NIT was independently associated with the presence of NA (odds ratio 2.53, 95% confidence interval 1.96 to 3.27, p <0.001). This study demonstrates the presence of a positive correlation between degree of neointimal hyperplasia after stent implantation and presence of lipid-laden intima. This association is independent from stent type and time from implantation and suggests a possible pathogenic link between the two processes.

Comparison of incidence and time course of neoatherosclerosis between bare metal stents and drug-eluting stents using optical coherence tomography

Recent studies have reported the development of neoatherosclerosis inside stents and subsequent acute coronary syndrome secondary to disruption of neointimal hyperplasia. The aim of the study was to compare the characteristics of neointimal hyperplasia and its time course between bare metal stents (BMSs) and drug-eluting stents (DESs) using optical coherence tomography. A total of 138 stents were divided into 3 groups according to the follow-up period: early phase, <9 months (25 BMSs and 27 DESs); intermediate phase, ≥9 and <48 months (18 BMSs and 43 DESs); and delayed phase, ≥48 months (13 BMSs and 12 DESs). Optical coherence tomographic analysis included the presence of lipid-laden intima, percentage of lipid-rich plaque, and signal attenuation. The optical coherence tomographic findings were compared between the BMSs and DESs in each period, and the difference between the periods was also determined. In the early phase, a greater incidence of lipid-laden plaque (37% vs 8%, p = 0.02) and a greater percentage of lipid-rich plaque (12.9 ± 25.1% vs 1.2 ± 4.3%, p = 0.01) were found in the DESs than in the BMSs. In the intermediate phase, the DES group continuously showed a significantly greater incidence of lipid-laden plaque (63% vs 28%, p = 0.03) and greater percentage of lipid-rich plaque (24.8 ± 28.1% vs 4.1 ± 7.3%, p <0.01). In addition, signal attenuation was greater in the DES group, suggesting early changes in neointimal hyperplasia properties. In the delayed phase, lipid-laden plaque was the predominant type in both groups. In conclusion, lipid-rich neoatherosclerosis develops inside stents earlier in DESs than in BMSs. After 48 months, most restenotic stents will have developed lipid-laden neointima in both groups.