Impact of stent strut link location in proximal balloon edge dilation technique for bifurcation percutaneous coronary intervention

The single-stent strategy has generally been accepted as the default approach to bifurcation percutaneous coronary intervention. We have proposed the proximal balloon edge dilation (PBED) technique to prevent stent deformation during side branch (SB) dilation. This bench study aimed to evaluate the impact of stent link location and stent design on stent deformation, obstruction by stent struts at a jailed SB ostium, and incomplete stent apposition in the proximal optimization technique (POT)-PBED procedure. A coronary bifurcation model was used. We intentionally set the absence or presence of stent link on the carina (link-free or link-connect) under videoscope observation and compared stent parameters between 3- and 2-link stents (n = 5 each, n = 20 total). In the link-free group, the SB jailing rate of 3-link stents was significantly higher than that of 2-link stents (15.5 ± 5.1% vs. 6.6 ± 1.2%, p = 0.009). In the link-connect group, the SB jailing rate of 3-link stents was significantly lower than that of 2-link stents (30.0 ± 4.5% vs. 39.0 ± 2.6%, p = 0.009). In the bifurcation segment, the rate of incomplete stent apposition was significantly lower for 3-link stents of the link-connect group than for 2-link stents of the link-connect group (3.3 ± 4.2% vs. 19.0 ± 7.8%, p = 0.009). For both stent designs, ellipticity ratio was higher for link-connect group than link-free group. Link location as well as stent cell design greatly impacted stent deformation during the POT-PBED procedure.

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.

Impact of Coronary Stent Design in Proximal Balloon Edge Dilation Technique for Bifurcation Percutaneous Coronary Intervention

The proximal optimizing technique (POT) -proximal balloon edge dilation (PBED) sequence for side branch (SB) dilatation with cross-over single-stent implantation decreases both strut obstruction at the SB ostium and stent deformation at the main branch (MB).The purpose of this experimental bench test was to assess the impact of stent design on stent deformation, obstruction by stent struts at a jailed SB ostium, and stent strut malapposition in the POT-PBED sequence.Fractal coronary bifurcation bench models (60- and 80-degree angles) were used, and crossover single-stent implantation (3-link stent: XIENCE Sierra, Abbott Vascular, Santa Clara, CA, n = 10; 2-link stent: Synergy, Boston Scientific, Marlborough, MA, n = 10) was performed from the MB using the POT-PBED sequence. Jailing rates at the SB ostium, stent deformation, and stent strut malapposition of the bifurcation segment were assessed using videoscopy and optical coherence tomography.After SB dilatation using the PBED technique, jailing rates at the SB ostium and stent deformation did not differ significantly between the two types of stents. Conversely, the rate of malapposed struts of the bifurcation segment after the PBED procedure was significantly lower with 3-link stents than with 2-link stents for both 60- and 80-degree angles (60-degree angle: 4.3% ± 4.4% versus 22.0% ± 11.1%, P = 0.044; 80-degree angle: 20.8% ± 15.1% versus 57.2% ± 17.0%, P < 0.001, respectively).In the POT-PBED sequence, 3-link stents might be a preferable coronary bifurcation stent, maintaining a jailed SB ostium while significantly reducing stent strut malapposition of the bifurcation segment when compared with 2-link stents.

Influence of dual antiplatelet therapy duration on neointimal condition after second-generation drug-eluting stent implantation

Guidelines recommend shorter duration (1–12 months) for dual antiplatelet therapy (DAPT) in the second-generation drug-eluting stent (DES) era. However, whether shorter DAPT duration affects stent strut conditions and neointimal characteristics at mid-term follow-up remains uncertain. Therefore, we studied the relation between DAPT duration and vascular healing response as assessed by optical coherence tomography (OCT). This study was retrospective observational study. Participants comprised 64 patients who underwent serial OCT at both 9 and 18 months after DES implantation. All patients received DAPT until the 9-month follow-up then were divided into two groups: 49 patients who continued DAPT (longer DAPT group); and 15 patients who stopped taking the P2Y12 inhibitor and were treated with aspirin alone (shorter DAPT group) at the 18-month follow-up. Using OCT, we evaluated and compared stent strut conditions and neointimal characteristics between groups at both 9 and 18 months after stent implantation. Baseline clinical and procedural parameters were mostly similar between groups. At the 18-month follow-up, no in-stent thrombus assessed by OCT was observed in either group. No significant differences in OCT characteristics or measurements of neointima were seen between groups at 9- or 18-month follow-ups. Neointimal volume increased from 9 to 18 months in both groups, with a similar degree of neointimal proliferation in both groups (shorter DAPT group, 0.23 ± 0.29 mm³/mm; longer DAPT group, 0.19 ± 0.27 mm³/mm; P = 0.56). In conclusion, interrupting DAPT 9 months after second-generation DES implantation did not affect the development of in-stent thrombus, neointimal proliferation or stent strut coverage at 18-month follow-up compared with continuing DAPT.

Effect of proximal balloon edge dilation technique for opening a side branch ostium in repetitive-proximal optimizing technique sequence

OBJECTIVE

The purpose of this experimental bench test was to compare stent deformation, obstruction of stent struts at a jailed side branch (SB) ostium, and stent strut malapposition between SB inflation using proximal balloon edge dilation (PBED) technique and SB inflation using conventional balloon dilation in repetitive-proximal optimizing technique (re-POT) sequence.

BACKGROUND

The second proximal optimizing technique (POT) procedure in the re-POT sequence might increase obstruction of stent struts at a jailed SB ostium, because deformation of stent cells at the main branch (MB) occurred during SB inflation for opening the SB ostium.

METHODS

A fractal coronary bifurcation bench model made of flexible urethane was used, and crossover single-stent implantation (Xience Sierra, Abbott Vascular, Santa Clara, CA, n = 12) was performed from the MB with the re-POT sequence. During the re-POT sequence, the jailing rate at the SB ostium assessed by videoscopy was compared between SB inflation using PBED technique (PBED group, n = 6) and SB inflation using conventional balloon dilation (conventional group, n = 6).

RESULTS

The jailing rate after the second POT procedure tended to be lower in the PBED group than in the conventional group (26 ± 12% vs. 34 ± 8%, p = .211), and the change in the jailing rate during the second POT procedure was significantly smaller in the PBED group than in the conventional group (4.8 ± 5.3% vs. 11.6 ± 3.5%, p = .026).

CONCLUSIONS

In the re-POT sequence, the PBED technique with a short balloon for SB inflation might minimize worsening of the jailing rate at the SB ostium during the second POT procedure.

Coronary bifurcation bench test using multimodality imaging: Impact of stent strut link location on stent deformity and jailed side-branch orifices during re-proximal optimizing technique

OBJECTIVES

The purpose of this study was to compare the stent deformation, obstruction of stent struts at a jailed side branch (SB) ostium, and stent strut malapposition after a repetitive proximal optimizing technique (re-POT) sequence between bifurcation lesions with and without stent links at SB ostia in ex vivo experimental setting.

METHODS

A flexible urethane coronary bifurcation bench model was used, and crossover single stent implantation was performed from main branch (MB) with re-POT sequence. Under videoscope observation, presence (link group, n = 12) or absence (no-link group, n = 12) of stent link at distal semicircle of SB ostium was intentionally set, and rewiring was performed through distal cell in four different stent platforms.

RESULTS

There were no significant differences in the rate of malapposed struts and in SB jailing ratio after the re-POT sequence between the link and no-link groups. SB jailing ratio increased significantly from 8.0% to 9.6% during the second POT procedure (P < 0.001). SB jailing ratio after the second POT procedure differed among stent platforms.

CONCLUSIONS

The presence of a stent link at an SB ostium was not associated with a rate of malapposed struts and SB jailing ratio after the re-POT sequence. SB jailing ratio was significantly increased after second POT procedure, but was different among stent platforms. The Xience stent might minimize the change of SB jailing ratio and be suitable for coronary bifurcation stenting using re-POT sequence.

IVUS-Guided Versus OCT-Guided Coronary Stent Implantation: A Critical Appraisal

Procedural guidance with intravascular ultrasound (IVUS) imaging improves the clinical outcomes of patients undergoing percutaneous coronary intervention (PCI) by: 1) informing the necessity for lesion preparation; 2) directing appropriate stent sizing to maximize the final stent area and minimize geographic miss; 3) selecting the optimal stent length to cover residual disease adjacent to the lesion, thus minimizing geographic miss; 4) guiding optimal stent expansion; 5) identifying acute complications (edge dissection, stent malapposition, tissue protrusion); and 6) clarifying the mechanism of late stent failure (stent thrombosis, neointimal hyperplasia, stent underexpansion or fracture, or neoatherosclerosis). Optical coherence tomography (OCT) provides similar information to IVUS (with some important differences), also potentially improving acute and long-term patient outcomes compared to angiography-guided PCI. The purpose of this review is to describe the similarities and differences between IVUS and OCT technologies, and to highlight the evidence supporting their utility to improve PCI outcomes.

Biodegradable polymer-based, argatroban-eluting, cobalt-chromium stent (JF-04) for treatment of native coronary lesions: final results of the first-in-man study and lessons learned

AIMS

The aim of the study was to investigate the six-month angiographic and nine-month clinical follow-up outcomes in a first-in-man study using the biodegradable polymer-based cobalt-chromium argatroban-eluting stent (JF-04) for treatment of native coronary atherosclerotic lesions.

METHODS AND RESULTS

A total of 31 patients with either stable or unstable angina, or silent myocardial ischaemia, exhibiting de novo coronary lesions were enrolled at seven Japanese sites. The lesions were treated with the JF-04 stent after predilatation. The primary endpoint was angiographic in-stent late loss six months after implantation. The secondary endpoints included angiographic restenosis and in-stent volume obstruction by intravascular ultrasound at six months and target vessel failure (TVF) at nine months. Procedural success was achieved in 100% of cases. At six months, angiographic in-stent late loss was 1.01±0.48 mm and binary restenosis was observed in nine cases (29.0%). Among these restenotic cases, most (n=8) demonstrated advanced angiographic restenosis patterns, including diffuse/proliferative restenosis and total occlusion. At nine months, TVF was observed in four cases (12.9%), exclusively attributed to target vessel revascularisation.

CONCLUSIONS

This argatroban-eluting stent failed to inhibit neointimal hyperplasia sufficiently, despite the theoretical benefits and promising clinical experience with local drug delivery.

Wall Apposition Is a Key Factor for Aneurysm Occlusion after Flow Diversion: A Histologic Evaluation in 41 Rabbits

BACKGROUND AND PURPOSE

Robust wall apposition for flow-diverter stents may be important for endothelialization. Using a large series of experimental aneurysms treated with the Pipeline Embolization Device, the objectives of this study were to 1) assess interobserver agreement for the evaluation of wall apposition on posttreatment DSA and evaluate its association with aneurysm occlusion, and 2) measure the relationship between wall apposition assessed with histology and aneurysm occlusion rate after treatment.

MATERIALS AND METHODS

Saccular aneurysms were created in 41 rabbits and treated with the Pipeline Embolization Device. DSA was performed just after the deployment of the device and at follow-up. Three investigators independently graded wall apposition on posttreatment DSA as good or poor. A histopathologist blinded to the angiographic results graded the wall apposition on histologic samples. We examined the correlation between angiographic occlusion and wall apposition with histology and angiography.

RESULTS

Wall apposition evaluated on histology was strongly associated with saccular aneurysm occlusion. Sensitivity and specificity of wall apposition to predict complete occlusion at follow-up were 76.9% and 84.0%, respectively, with an overall accuracy of 81.6%. In this experimental study, DSA was suboptimal to assess flow-diverter apposition, with moderate interobserver agreement and low accuracy.

CONCLUSIONS

Good wall apposition is strongly associated with complete occlusion after flow-diverter therapy. In this study, DSA was suboptimal for assessing wall apposition of flow-diverter stents. These findings suggest that improved tools for assessing flow diverter-stent wall apposition are highly relevant.

Assessment and Quantitation of Stent Results by Intracoronary Optical Coherence Tomography

Optical coherence tomography evaluation of poststent results includes stent expansion as the absolute minimum stent area ratio by comparing the minimum stent area with the proximal and distal reference lumen areas or mean stent area defined as the total stent volume divided by the analyzed stent length; stent strut malapposition defined when the distance from the center of the blooming artifact and the surface of plaque is greater than the sum of stent thickness and polymer thickness; tissue protrusion through the stent struts; semiquantitative residual thrombus evaluation; and stent edge dissection.

Vascular Response After Zilver PTX Stent Implantation for Superficial Femoral Artery Lesions

Purpose: To compare the vascular response after paclitaxel-coated nitinol drug-eluting stent (Zilver PTX) implantation for superficial femoral artery lesions after 6 and 12 months using optical coherence tomography (OCT). Methods: Serial OCT examinations were performed in 5 patients (4 men; mean age 78.4±6.8 years) with 9 Zilver PTX stents at 6- and 12-month follow-up. Variables evaluated included neointimal thickness and apposition on each strut, the incidence of extrastent lumen (ESL), peristrut low-intensity area (PLIA), and neovascularization at 1-mm intervals. Results: A total of 249 matched cross-section images were evaluated and included 4788 and 4826 struts at 6 and 12 months, respectively. Mean neointimal thickness significantly increased from 480 to 540 µm between 6 and 12 months (p<0.001). The percentage of uncovered struts tended to decrease at 12 months (3% vs. 2.3%, p=0.054), whereas the percentage of malapposed struts were similar at both examinations (0.2% vs. 0.2%, p>0.99). Although the incidence of ESL in cross sections was not different (35% vs. 31%, p=0.29), median ESL area significantly increased from 6 to 12 months [0.12 (0.04–0.36) vs. 0.31 (0.14–0.59) mm2, p=0.003)]. The presence of PLIA (29% vs. 44%, p<0.001) and neovascularization (14% vs. 27%, p<0.001) increased from 6 to 12 months. Conclusion: These findings suggest that delayed vascular healing and persistent peristent inflammation may be present even at 12 months after Zilver PTX implantation.

Mechanism of luminal patency of the self-expanding Sideguard sidebranch stent: evaluation by intravascular ultrasound and optical coherence tomography

BACKGROUND

The Cappella Sideguard (CS) sidebranch stent is a self-expanding, thin-strut, nitinol device with anatomic flaring at the sidebranch ostium designed to treat bifurcation lesions.

OBJECTIVE

To evaluate the mechanism of long-term lumen patency of the novel, self-expanding CS sidebranch stent compared with a balloon-expandable stent in the main vessel.

METHODS

We performed intravascular ultrasound postintervention and at follow-up in 24 CS stents and in 28 balloon-expandable drug-eluting stents deployed in the corresponding main vessel. Thirteen patients also had optical coherence tomography (OCT) at follow-up to evaluate neointimal hyperplasia and strut coverage.

RESULTS

CS stent area at the sidebranch carina increased significantly from 3.8 ± 1.2 mm(2) postintervention to 4.6 ± 1.2 mm(2) at follow-up (P < 0.001), resulting in no change in lumen area (3.8 ± 1.2 mm(2) to 3.7 ± 1.2 mm(2) , P = 0.72) despite a neointimal area at follow-up of 0.9 ± 0.8 mm(2) . Volumetric changes were similar, and the distribution of neointimal hyperplasia peaked 1-2 mm distal to the carina. Change of lumen volume inversely correlated to the neointimal volume (R = -0.48, P < 0.001), but correlated positively to the change in stent volume (R = 0.52, P < 0.0001). By OCT, most CS struts were covered (100% [98.9, 100]) at the bifurcation site, whereas 61% of floating DES struts that crossed the sidebranch were covered by smooth tissue with a similar texture compared with neointima.

CONCLUSION

Although neointimal hyperplasia accumulates within the CS stent mainly 1-2 mm distal to the carina, the self-expanding CS stent may be effective in maintaining an adequate patency in the sidebranch by continued stent expansion noted at follow-up.

Research and clinical applications of optical coherence tomography in invasive cardiology: a review

In cardiology, optical coherence tomography (OCT) is an invasive imaging technique based on the principle of light coherence. This system was developed to obtain three-dimensional high resolution images to examine coronary artery normal and/or pathological structure. This technique replaces the ultrasound used by its main alternative procedure, intravascular ultrasound, by a near-infrared light source. Acute coronary syndromes due to atherosclerotic vascular disease are the leading cause of mortality in developed and developing countries. As a consequence, intravascular imaging systems became an important area of research and 1991 marks the first use of OCT in coronary artery observations. Since its first appearance in invasive cardiology, OCT maintains a strong presence in the research environments for the identification of vulnerable plaques, as it is able to overcome difficulties presented by other techniques such as virtual intravascular ultrasound, near-infrared spectroscopy, and histology. Moreover, OCT is increasingly being used in the clinical practice as a guide during coronary interventions and in the assessment of vascular response after coronary stent implantation. This review focuses on the relevance of OCT in research and clinical applications in the field of invasive cardiology and discusses the future directions of the field.

A novel method to assess coronary artery bifurcations by OCT: cut-plane analysis for side-branch ostial assessment from a main-vessel pullback

AIMS

In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB.

METHODS AND RESULTS

Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) cut-plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with cut-plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: rcut-plane = 0.927 vs. rconventional = 0.870, P = 0.256; mean diameter: rcut-plane = 0.918 vs. rconventional = 0.788, P = 0.056; minimum diameter: rcut-plane = 0.841 vs. rconventional = 0.812, P = 0.734; maximum diameter: rcut-plane = 0.770 vs. rconventional = 0.635, P = 0.316). Cut-plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm(2), P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001).

CONCLUSION

Measurements of SB ostium performed in a laboratory setting by cut-plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.

A rabbit model of spontaneous thrombosis induced by lipopolysaccharide

AIM

Inflammation plays a critical role in the development of atherosclerotic plaque, and lipopolysaccharide (LPS) is a potentially important source of inflammation. The aim of this study was to develop a rabbit model of spontaneous thrombosis mimicking the pathophysiological and morphological characteristics of atherosclerotic plaque in humans.

METHODS

The rabbits were randomized into four groups: group A (n=10) received a normal diet; group B (n=10) received a regular diet and weekly LPS injections (1 μg/kg, Escherichia coli); group C (n=15) received a cholesterol-enriched diet before and after sustaining a balloon injury to the right common carotid artery; and group D (n=15) was treated the same as group C in addition to receiving LPS injections. The morphological characteristics of the resulting lesions were evaluated using optical coherence tomography (OCT) and histology.

RESULTS

No significant atherosclerotic plaque was observed in groups A or B. Group D exhibited a higher incidence of spontaneous luminal thrombi than group C or B (60% vs. 20% vs. 10%, p<0.05). All of the thrombi detected with OCT were confirmed on histology. A good correlation between the fibrous cap thickness and thrombus arc was obtained on OCT and the histological evaluations.

CONCLUSIONS

A rabbit model of LPS-induced spontaneous thrombosis was developed in which OCT was used to follow changes in plaque morphology.

OCT compared with IVUS in a coronary lesion assessment: the OPUS-CLASS study

OBJECTIVES

The aim of this study was to investigate the reliability of frequency domain optical coherence tomography (FD-OCT) for coronary measurements compared with quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS).

BACKGROUND

Accurate luminal measurement is expected in FD-OCT because this technology offers high resolution and excellent contrast between lumen and vessel wall.

METHODS

In 5 medical centers, 100 patients with coronary artery disease were prospectively studied by using angiography, FD-OCT, and IVUS. In addition, 5 phantom models of known lumen dimensions (lumen diameter 3.08 mm; lumen area 7.45 mm(2)) were examined using FD-OCT and IVUS. Quantitative image analyses of the coronary arteries and phantom models were performed by an independent core laboratory.

RESULTS

In the clinical study, the mean minimum lumen diameter measured by QCA was significantly smaller than that measured by FD-OCT (1.81 ± 0.72 mm vs. 1.91 ± 0.69 mm; p < 0.001) and the minimum lumen diameter measured by IVUS was significantly greater than that measured by FD-OCT (2.09 ± 0.60 mm vs. 1.91 ± 0.69 mm; p < 0.001). The minimum lumen area measured by IVUS was significantly greater than that by FD-OCT (3.68 ± 2.06 mm(2) vs. 3.27 ± 2.22 mm(2); p < 0.001), although a significant correlation was observed between the 2 imaging techniques (r = 0.95, p < 0.001; mean difference 0.41 mm(2)). Both FD-OCT and IVUS exhibited good interobserver reproducibility, but the root-mean-squared deviation between measurements was approximately twice as high for the IVUS measurements compared with the FD-OCT measurements (0.32 mm(2) vs. 0.16 mm(2)). In a phantom model, the mean lumen area according to FD-OCT was equal to the actual lumen area of the phantom model, with low SD; IVUS overestimated the lumen area and was less reproducible than FD-OCT (8.03 ± 0.58 mm(2) vs. 7.45 ± 0.17 mm(2); p < 0.001).

CONCLUSIONS

The results of this prospective multicenter study demonstrate that FD-OCT provides accurate and reproducible quantitative measurements of coronary dimensions in the clinical setting.

The role of optical coherence tomography in coronary intervention

Optical coherence tomography (OCT) is an optical analog of intravascular ultrasound (IVUS) that can be used to examine the coronary arteries and has 10-fold higher resolution than IVUS. Based on polarization properties, OCT can differentiate tissue characteristics (fibrous, calcified, or lipid-rich plaque) and identify thin-cap fibroatheroma. Because of the strong attenuation of light by blood, OCT systems required the removal of blood during OCT examinations. A recently developed frequency-domain OCT system has a faster frame rate and pullback speed, making the OCT procedure more user-friendly and not requiring proximal balloon occlusion. During percutaneous coronary intervention (PCI), OCT can provide detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition [ISA]). At follow-up examinations after stent implantation, stent strut coverage and ISA can be assessed. Several OCT studies have demonstrated delayed neointimal coverage following drug-eluting stent (DES) implantation vs. bare metal stent (BMS) placement. While newer DESs promote more favorable vascular healing, the clinical implications remain unknown. Recent OCT studies have provided insights into restenotic tissue characteristics; DES restenotic morphologies differ from those with BMSs. OCT is a novel, promising imaging modality; with more in-depth assessments of its use, it may impact clinical outcomes in patients with symptomatic coronary artery disease.

Natural history of stent edge dissection, tissue protrusion and incomplete stent apposition detectable only on optical coherence tomography after stent implantation – preliminary observation –

BACKGROUND

The clinical impact of stent edge dissection, tissue protrusion, and incomplete stent apposition (ISA) after stent implantation, detectable only on optical coherence tomography (OCT), is still unknown because the natural course has not been investigated.

METHODS AND RESULTS

All consecutive patients with angina pectoris in whom both intravascular ultrasound (IVUS) and OCT were performed immediately after stenting and at follow-up were included in the present study. The natural history of OCT-detected stent edge dissection, tissue protrusion, and ISA during follow-up was investigated. A total of 36 patients with 39 lesions was analyzed. At baseline, OCT showed 12 stent edge dissections, 25 tissue protrusions, and 8 ISAs, whereas IVUS demonstrated 6 stent edge dissections, 5 tissue protrusions, and 3 ISAs. All IVUS findings were clearly visualized on OCT. The maximum length of dissection flap and depth of ISA visualized on OCT were significantly shorter than those visualized on IVUS. Maximum length of tissue protrusion tended to be smaller on OCT than on IVUS. At follow-up (median 188 days), all findings noted on OCT were healed or resolved without any restenosis or thrombus formation.

CONCLUSIONS

Acute findings after stenting, such as edge dissection, tissue protrusion, and ISA, detectable only on OCT, tended to be smaller than those seen on both OCT and IVUS. The majority of OCT-detected acute findings resolved completely at follow-up.

Current status of optical coherence tomography

Optical coherence tomography (OCT) is a novel imaging technology based on low-coherence interferometry that use near-infrared light in real-time, and allows cross-sectional in-situ visualization of the vessel wall at the microscopic level. OCT provides 10-fold higher resolution than intravascular ultrasound which is currently the most used modality for intra-coronary imaging. OCT offers the obvious advantages when characterizing precise plaque microstructure and distinguishing various type of plaques. OCT is also being assessed for its potential role in the understanding of neointimal coverage, vascular healing and the progression of atherosclerosis in coronary vasculature after stenting on the micron scale. These unique capabilities could be helpful in guiding coronary management and interventions. Recent improvement in next generation OCT technology, such as frequency-domain OCT, will allow for a simple imaging procedure, providing more useful information and complementing other modalities on both clinical and research applications for the cardiologists.

Recent progress in the management of pulmonary hypertension

Pulmonary hypertension (PH) is a fatal disease caused by small pulmonary artery obstruction from vascular proliferation and remodeling. PH is characterized by elevated pulmonary arterial pressure and increased pulmonary vascular resistance, frequently leading to right-sided heart failure and death. The classification of PH has been recently updated to include 5 major categories of the disorder, are as: Group 1, pulmonary arterial hypertension (PAH); Group 2, PH due to left heart disease; Group 3, PH due to lung diseases and/or hypoxia; Group 4, chronic thromboembolic PH (CTEPH); and Group 5, others. Recently, significant progress has been made in the understanding of the pathophysiology, diagnosis and treatment of PH. Regarding the pathophysiology of the disorder, direct evidence for Rho-kinase activation in the pulmonary artery from PAH patients has been provided. Regarding diagnosis, optical coherence tomography is useful as a new differential diagnostic tool for distal type CTEPH vs. PAH. Regarding treatment, in addition to the conventional therapy, several new drugs are under clinical trial, including fasudil (a Rho-kinase inhibitor), riosiguat (a soluble guanylate cyclase activator), and imatinib (a tyrosine kinase inhibitor). In addition, pulmonary angioplasty and intensive immunosuppressive therapy may be effective for CTEPH and connective tissue disease-associated PAH, respectively. We briefly review the recent progress in the management of PH.

Fusion of 3D QCA and IVUS/OCT

The combination/fusion of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS)/optical coherence tomography (OCT) depends to a great extend on the co-registration of X-ray angiography (XA) and IVUS/OCT. In this work a new and robust three-dimensional (3D) segmentation and registration approach is presented and validated. The approach starts with standard QCA of the vessel of interest in the two angiographic views (either biplane or two monoplane views). Next, the vessel of interest is reconstructed in 3D and registered with the corresponding IVUS/OCT pullback series by a distance mapping algorithm. The accuracy of the registration was retrospectively evaluated on 12 silicone phantoms with coronary stents implanted, and on 24 patients who underwent both coronary angiography and IVUS examinations of the left anterior descending artery. Stent borders or sidebranches were used as markers for the validation. While the most proximal marker was set as the baseline position for the distance mapping algorithm, the subsequent markers were used to evaluate the registration error. The correlation between the registration error and the distance from the evaluated marker to the baseline position was analyzed. The XA-IVUS registration error for the 12 phantoms was 0.03 ± 0.32 mm (P = 0.75). One OCT pullback series was excluded from the phantom study, since it did not cover the distal stent border. The XA-OCT registration error for the remaining 11 phantoms was 0.05 ± 0.25 mm (P = 0.49). For the in vivo validation, two patients were excluded due to insufficient image quality for the analysis. In total 78 sidebranches were identified from the remaining 22 patients and the registration error was evaluated on 56 markers. The registration error was 0.03 ± 0.45 mm (P = 0.67). The error was not correlated to the distance between the evaluated marker and the baseline position (P = 0.73). In conclusion, the new XA-IVUS/OCT co-registration approach is a straightforward and reliable solution to combine X-ray angiography and IVUS/OCT imaging for the assessment of the extent of coronary artery disease. It provides the interventional cardiologist with detailed information about vessel size and plaque size at every position along the vessel of interest, making this a suitable tool during the actual intervention.

Tissue characterization of coronary plaques and assessment of thickness of fibrous cap using integrated backscatter intravascular ultrasound. Comparison with histology and optical coherence tomography

BACKGROUND

The purpose of this study was to develop a new online integrated backscatter intravascular ultrasound (IB-IVUS) system and to validate its ability to measure fibrous cap thickness by comparing IB-IVUS images with those from optical coherence tomography (OCT).

METHODS AND RESULTS

Images were acquired from 125 segments of 26 coronary arteries obtained at autopsy from 11 cadavers. In the training study (n=30), 242 regions-of-interest on color-coded maps were compared with histology. In the validation study, 95 cross-sections were diagnosed by IB-IVUS and histology. In 24 patients with stable angina, 28 arterial cross-sections were imaged by IB-IVUS and OCT in vivo. In the training study, cutoff values of 39 decibels (dB) and 17dB were the optimal predictors of lipid pool/fibrosis and fibrosis/calcification, respectively, with 38-MHz mode; 42dB and 20dB, respectively, with 43-MHz mode. In the validation study, IB classified the fibrous, lipid-rich and fibrocalcific components with an accuracy of 92%, 91% and 95%, respectively. Agreement between the histological and IB-IVUS diagnoses was excellent (Cohen's κ=0.83). There was a correlation between the fibrous cap thickness measured by IB-IVUS and OCT (r=0.74, P<0.001).

CONCLUSIONS

The IB-IVUS system with improved resolution provides high diagnostic accuracy for the analysis of the tissue characteristics of coronary plaques, and enables estimation of the thickness of the fibrous cap in the clinical setting.

STELLIUM 1: First-in-man follow-up evaluation of bioabsorbable polymer-coated paclitaxel-eluting stent

BACKGROUND

Durable polymers used for first-generation drug-eluting stents (DES) potentially contribute to persistent inflammation and late DES thrombosis. The vascular response to the Stellium stent, which is coated with an absorbable polymer for slow release of low-dose paclitaxel, was evaluated in the present study.

METHODS AND RESULTS

The 37 patients with stable angina were implanted with 47 Stellium stents. Quantitative coronary angiography (QCA) was performed at baseline, and QCA and optical coherence tomography (OCT) were performed at 6 months post-implant. The primary endpoint was major adverse cardiac events (MACE). At 6 months, 1 case of MACE occurred because of total occlusion of a protected left main artery. In-stent and segment binary restenosis rates were both 0%. In-stent late loss was 0.19 ± 0.54 mm. Altogether, 5,564 struts were visualized by OCT and mean neointimal thickness was 150.03 ± 146.36 µm. The number of well-apposed struts with and without neointima overlay was 5,135 (92.29%) and 396 (7.12%), respectively. Peri-strut low intensity was observed in 518 struts (9.31%).

CONCLUSIONS

This first-in-man study of the Stellium stent shows the promising possibility of bioabsorbable polymeric surface coating paclitaxel-eluting stents out to 6 months. The low rate of peri-strut low intensity suggests low cellular toxicity of the Stellium stent compared with the first-generation DES.