Variable histological and ultrasonic characteristics of restenosis after drug-eluting stents

Prediction of Slow-Flow Phenomenon After Stent Implantation Using Near-Infrared Spectroscopy in Patients With Acute and Chronic Coronary Syndrome

BACKGROUND

The slow-flow phenomenon is associated with worse clinical outcomes after percutaneous coronary intervention (PCI), so our goal for this study was to see how predictive how near-infrared spectroscopy (NIRS) could be.

METHODS AND RESULTS

We enrolled 179 lesions from 152 patients who had de novo coronary stent implantation guided by NIRS-intravascular ultrasound (IVUS) (male: 69.1%, mean age: 74.3±11.5 years, acute coronary syndrome: 65.1%, diabetes: 42.1%). NIRS automatically determined the maximum 4-mm lipid core burden index (maxLCBI4 mm) value at pre- and post-PCI procedures. The slow-flow phenomenon was defined as the deterioration of TIMI (Thrombolysis in Myocardial Infarction) flows on angiography during the PCI procedure in the absence of mechanical obstruction. The slow-flow phenomenon occurred in 13 (7.3%) lesions, and the slow-flow phenomenon group had a significantly higher maxLCBI4 mm(740±147 vs. 471±223, P<0.001). The best maxLCBI4 mmcutoff point in both acute and chronic coronary syndrome was 578 and 480, with sensitivity of 100%, for predicting the slow-flow phenomenon. In the receiver-operating characteristics analysis, the area under the curve for acute and chronic coronary syndrome was 0.849 and 0.851, respectively.

CONCLUSIONS

The results of this study support the utility of NIRS-IVUS-guided PCI for the prediction of the slow-flow phenomenon.

Time course of restenosis with "black hole" on intravascular ultrasound after implantation of platinum-chromium everolimus-eluting stent: Assessment using optical frequency-domain imaging

Management of in-stent restenosis (ISR) remains challenging even in the drug-eluting stent era. We report the case of a Japanese female with repeated ISR after primary percutaneous coronary intervention (PCI) for acute coronary syndrome. We observed ISR tissue with "black hole" on intravascular ultrasound, which appeared to be heterogeneous tissue on optical frequency-domain imaging (OFDI). Paclitaxel-coated balloon dilatation of the ISR lesion with "black hole" was ineffective. The morphological assessment of ISR tissue using OFDI might be important to treat ISR lesions by PCI. OFDI is a novel tool to observe the difference in the in-stent tissue characteristics. <Learning objective: In-stent restenosis (ISR) remains a clinical problem even in the drug-eluting stent (DES) era. The morphological assessment of ISR tissue using optical frequency-domain imaging (i.e. homogeneous, heterogeneous, and layered types) might be important to treat ISR lesions by percutaneous coronary intervention since the reaction to DES and drug-coating balloon seems to be different according to the in-stent tissue characteristics.>.

Clinical Impact of Suboptimal Stenting and Residual Intrastent Plaque/Thrombus Protrusion in Patients With Acute Coronary Syndrome

Background—

Clinical consequences of optical coherence tomographic (OCT) high-definition visualization of plaque/stent structures in acute patients remain undefined. In this retrospective substudy, we assessed the prognostic impact of postprocedural culprit lesion OCT findings in patients with acute coronary syndrome undergoing percutaneous coronary intervention.

Methods and Results—

In the CLI-OPCI (Centro per la Lotta Contro L’Infarto-Optimization of Percutaneous Coronary Intervention) database collecting cases from 5 independent OCT-experienced centers, we retrospectively analyzed postprocedural OCT findings in acute coronary syndrome patients and explored its possible impact (specifically that of residual intrastent plaque/thrombus protrusion) on outcome. From 2009 to 2013, 507 patients (588 lesions) were evaluated. Patients experiencing device-oriented cardiovascular events showed more frequently the features of suboptimal stent implantation defined as the presence of significant residual intrastent plaque/thrombus protrusion (hazard ratio [HR], 2.35; P <0.01), in-stent minimum lumen area (MLA) <4.5 mm 2 (HR, 2.72; P <0.01), dissection >200 µm at distal stent edge (HR, 3.84; P <0.01), and reference lumen area <4.5 mm 2 at either distal (HR, 6.07; P <0.001) or proximal (HR, 8.50; P <0.001) stent edges. Postprocedural OCT assessment of treated culprit lesion revealed at least one of these parameters in 55.2% of cases, with an associated increased risk of device-oriented cardiovascular events during follow-up (17.9% versus 4.8%; P <0.001). Both the presence of at least one of these parameters (HR, 3.69; P =0.002) and the residual intrastent plaque/thrombus protrusion (HR, 2.83; P =0.008) were confirmed as independent predictors of device-oriented cardiovascular events.

Conclusions—

In this retrospective study of acute coronary syndrome patients undergoing percutaneous coronary intervention, a composite of OCT-defined suboptimal stent implantation characteristics at the culprit lesion and residual intrastent plaque/thrombus protrusion was associated with adverse outcome.

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.

microRNAs Distinctively Regulate Vascular Smooth Muscle and Endothelial Cells: Functional Implications in Angiogenesis, Atherosclerosis, and In-Stent Restenosis

Endothelial cells (EC) and vascular smooth muscle cells (VSMC) are the main cell types within the vasculature. We describe here how microRNAs (miRs)--noncoding RNAs that can regulate gene expression via translational repression and/or post-transcriptional degradation--distinctively modulate EC and VSMC function in physiology and disease. In particular, the specific roles of miR-126 and miR-143/145, master regulators of EC and VSMC function, respectively, are deeply explored. We also describe the mechanistic role of miRs in the regulation of the pathophysiology of key cardiovascular processes including angiogenesis, atherosclerosis, and in-stent restenosis post-angioplasty. Drawbacks of currently available therapeutic options are discussed, pointing at the challenges and potential clinical opportunities provided by miR-based treatments.

Quantitative optical coherence tomography analysis for late in-stent restenotic lesions

Coronary optical coherence tomography (OCT) has the potential to identify in-stent neoatherosclerosis, which is a possible risk factor for late acute coronary events after drug-eluting stent implantation. The purpose of this study was to investigate differences between mid-term and late in-stent restenosis after stent implantation by quantitative and semiautomated tissue property analysis using OCT. In total, 1063 OCT image frames of 16 lesions in 15 patients were analyzed. This included 346 frames of 6 lesions in late in-stent restenosis, which was defined as restenosis that was not detected at 6 to 12 months but ≥ 12 months after follow-up coronary angiography. Signal attenuation was circumferentially analyzed using a dedicated semiautomated software. Attenuation was assessed along 200 lines delineated radially for analysis of the in-stent restenotic lesions (between the lumen and stent contours). All lines were anchored by the image wire to avoid artifacts resulting from wire location. Stronger signal attenuation at the frame level (2.46 ± 0.78 versus 1.47 ± 0.32, P < 0.001) and higher maximum signal intensity at the lesion level (9.19 ± 0.19 versus 8.84 ± 0.32, P = 0.018) were observed in late in-stent restenotic lesions than in mid-term in-stent restenotic lesions. OCT demonstrated stronger signal attenuation and higher maximum signal intensity in late in-stent restenotic lesions than in mid-term in-stent restenotic lesions, indicating the possibility of neoatherosclerosis.

Vascular responses to drug-eluting and bare metal stents in diabetic/hypercholesterolemic and nonatherosclerotic porcine coronary arteries

BACKGROUND

Animal models used to gain insight into the vascular response to drug-eluting stents are generally juvenile and nonatherosclerotic, whereas stents are placed in patients with complex atherosclerosis and comorbidities. Hence, models reflecting these complexities are needed to help elucidate the vascular effects of drug-eluting stents. We compared the vascular responses with bare metal stent (BMS) and paclitaxel-eluting stent (PES) implantation in a diabetic/hypercholesterolemic (DM/HC) porcine model of advanced coronary atherosclerosis with the standard juvenile porcine model.

METHODS AND RESULTS

Two studies using similar stent procedural protocols were performed in either DM/HC (n=20) or domestic swine (non-DM/HC, n=20). Animals pretreated with dual-antiplatelet therapy, underwent BMS or PES implantation (1/artery, 2 stents per animal) and were euthanized 30 or 90 days later. DM/HC resulted in a 24% increase in platelet aggregation (P=0.05 versus baseline), whereas dual-antiplatelet therapy reduced platelet aggregation in both groups (P<0.0001). DM/HC pigs developed substantially greater neointimal area versus non-DM/HC pigs, regardless of stent type, (P=0.004 for BMS at 30 days and P=0.002 at 90 days, P=0.005 for PES at 30 days, P=0.002 at 90 days). Compared with non-DM/HC pigs, reendothelialization was delayed in DM/HC pigs, more so after PES implantation. Increased para-strut leukocytes were observed for PES compared with BMS in the DM/HC pigs at both 30 days (P=0.023) and 90 days (P=0.04). As well, increased T-lymphocyte infiltration was seen in the DM/HC pigs.

CONCLUSIONS

Stent implantation in a DM/HC swine model provides a metabolic environment closer to human disease, including hyperglycemia, hypercholesterolemia, and increased platelet aggregation. This model augmented differences in the vascular response between PES and BMS that are not as clearly evident in the non-DM/HC swine, including increased neointimal area, delayed reendothelialization, and greater, persistent vascular inflammation.

Late regression of Cypher in-stent restenosis

We encountered a case of late regression after sirolimus-eluting stent restenosis. We report this case with intravascular ultrasound imaging demonstrating an intraluminal echolucent tissue, which looks like a black hole.

Immune responses regulating the response to vascular injury

PURPOSE OF REVIEW

Immune modulation of neointimal formation after vascular injury has been investigated for several decades but the complexities involved continue to obscure a clearer understanding of the process. The rapidly changing field of immunology makes this knowledge imperative.

RECENT FINDINGS

The review discusses immune factors involved in the response to vascular injury. Although innate immune responses play a predominantly detrimental role, the adaptive immune response is more complex. Mechanisms of T-cell activation, recruitment, as well as possible regulation are highlighted.

SUMMARY

Progress in understanding the role of the immune system in the response to arterial injury has been impressive. However, recent findings underscore the need to unravel the intricacies involved such as the kinetics and specific pathways of activation, specificity of immune cell involvement, and identification of targets for therapy. This is relevant in light of the increasing reports of immune factors involved in vascular disease and intervention in the clinical setting.