Outcome after acute incomplete sirolimus-eluting stent apposition as assessed by serial intravascular ultrasound

Improving PCI Outcomes Using Postprocedural Physiology and Intravascular Imaging

Although clinical outcomes after percutaneous coronary intervention (PCI) are improving, the long-term risk for target vessel failure remains concerning. Although the application of intravascular imaging and physiological indexes significantly improves outcomes, their routine use in practice remains limited. Nevertheless, merely using these modalities is not enough, and to truly improve patient outcomes, optimal intravascular dimensions with minimal vascular injury should be targeted. When assessing post-PCI results using either type of physiological or imaging technology, a broad spectrum of stent- and vessel-related anomalies can be expected. As not all of these issues warrant treatment, a profound knowledge of what to expect and how to recognize and when to treat these intraluminal problems is needed. Additionally, promising new modalities such as angiography-derived coronary physiology and hybrid imaging catheters are becoming available. The authors provide an overview of the currently available tools and techniques to define suboptimal PCI and when to apply these technologies to improve outcomes.

A Prospective, observational, Italian multi-center registry of self-aPposing® cOronary Stents in patients presenting with ST-segment Elevation Myocardial InfarcTION: The iPOSITION registry

BACKGROUND

Primary percutaneous coronary intervention (pPCI) in ST-segment elevation myocardial infarction (STEMI) can be challenging for high thrombus burden and catecholamine-induced vasoconstriction. The Xposition-S stent was designed to prevent stent undersizing and minimize strut malapposition. We evaluated 1-year clinical outcomes of a nitinol, self-apposing®, sirolimus-eluting stent, pre-mounted on a novel balloon delivery system, in de novo lesions of patients presenting with STEMI undergoing pPCI.

METHODS

The iPOSITION is a prospective, multicenter, post-market, observational study. The primary endpoint, target lesion failure (TLF), was defined as the composite of cardiac death, recurrent target vessel myocardial infarction (TV-MI), and clinically driven target lesion revascularization (TLR).

RESULTS

The study enrolled 247 STEMI patients from 7 Italian centers. Both device and procedural success occurred in 99.2% of patients, without any death, TV-MI, TLR, or stent thrombosis during the hospital stay and at 30-day follow-up. At 1 year, TLF occurred in 2.6%, cardiac death occurred in 1.7%, TV-MI occurred in 0.4%, and TLR in 0.4% of patients. The 1-year stent thrombosis rate was 0.4%.

CONCLUSIONS

The use of an X-position S self-apposing® stent is feasible in STEMI pPCI, with excellent post-procedural results and 1-year outcomes.

Cut-off value of strut-vessel distance for the resolution of acute incomplete stent apposition in the early phase using serial optical coherence tomography after cobalt-chromium everolimus-eluting stent implantation

OBJECTIVE

The purpose of this study was to identify a cut-off value to predict the resolution of incomplete-stent-apposition (ISA) after cobalt-chromium everolimus-eluting stent (CoCr-EES) implantation at early follow-up.

BACKGROUND

To date, appropriate stent apposition at the acute period using intracoronary imaging has been recommended because persistent ISA is considered to be a risk factor for stent thrombosis. We examined the indices for resolving acute ISA. In particular, we determined the cut-off value for strut vessel distance (SV-distance) as visualized by optical coherence tomography (OCT) at 8 months after CoCr-EES implantation. However, the cut-off value of SV-distance for the earlier resolution of ISA is unclear.

METHODS

A total of 95 cases and 103 stents were registered in the MECHANISM Elective substudy. The SV-distance was measured at the deepest site of the target malapposition and every 1 mm from the proximal edge to the distal edge of the mal-apposed area using OCT. Cut-off values for ISA resolution at 1 and 3 months were estimated by SV-distance using receiver operating characteristic analysis.

RESULTS

The total number of analyzed struts was 14,418 at the 1-month follow-up and 11,986 at the 3-month follow-up. The optimal SV-distance cut-off values just after stent implantation to predict ISA resolution were 185 µm at the 1-month follow-up and 195 μm at the 3-month follow-up.

CONCLUSION

For resolution of ISA, SV-distance cut-off values of 185 µm at 1 month postimplantation and 195 μm at 3 months postimplantation can be used as the index of endpoint of the percutaneous coronary intervention.

Predictors and Long-Term Clinical Impact of Acute Stent Malapposition: An Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents (ADAPT-DES) Intravascular Ultrasound Substudy

BACKGROUND

The impact of acute stent malapposition (ASM) on long-term clinical outcomes in patients undergoing percutaneous coronary intervention is still controversial. We sought to evaluate predictors and long-term clinical outcomes of ASM.

METHODS AND RESULTS

ADAPT-DES (Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents) was a prospective multicenter study of 8663 patients undergoing percutaneous coronary intervention using drug-eluting stents. In a prespecified intravascular ultrasound-guided substudy, 2072 patients with 2446 culprit lesions had post-percutaneous coronary intervention intravascular ultrasound and were classified according to the presence or absence of ASM. After intravascular ultrasound-guided percutaneous coronary intervention, the overall prevalence of ASM after successful drug-eluting stents implantation was 14.4% per patient and 12.6% per lesion. Compared to lesions without ASM, lesions with ASM had larger in-stent lumen areas, larger stent areas, and larger in-stent vessel areas. A larger mean plaque area along with more attenuated plaque was observed in lesions with ASM versus lesions without ASM. Lesions with ASM had greater proximal and distal reference lumen areas and more distal, but not proximal, reference calcium compared to lesions without ASM. At 2-year follow-up, there was no significant difference in the incidence of cardiac death; myocardial infarction; early, late, or very late stent thrombosis; or clinically driven target lesion revascularization in patients with ASM versus those without ASM. Furthermore, ASM was not an independent predictor of 2-year major adverse cardiac events or target lesion revascularization even when forced into the multivariate model.

CONCLUSIONS

In patients treated with intravascular ultrasound-guided drug-eluting stents implantation, ASM was not associated with adverse clinical events during long-term follow-up including, but not limited to, stent thrombosis.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00638794.

Role of invasive imaging in acute and long-term assessment of bioresorbable scaffold technology

Fully bioresorbable scaffolds (BRS) represent a novel approach for the percutaneous treatment of coronary artery stenosis, providing temporary vessel scaffolding with drug-eluting capability during the restenosis-prone phase of the vascular healing. Beyond this initial critical period, when mechanical scaffolding support is no longer necessary, the device is bioresorbed, restoring the normal vascular physiology with the aim to eliminate the long-term safety concerns related to permanent metallic implants. Nonetheless, current BRS technology suffers from limited mechanical properties as compared to available metallic platforms, requiring careful attention to lesion preparation, accurate vessel sizing, and implantation technique. Intravascular imaging has played an important role in providing knowledge on the acute effects after BRS deployment, and it helped refine the current technique of BRS implantation. In addition, extensive work with multiple intravascular imaging modalities have also contributed to the understanding of the unique dynamic vascular changes that are experienced in the treated segment from post-implantation up to complete device bioresorption. In this manuscript, we review the role of invasive imaging modalities-from angiography to sound- and light-based techniques-to guide BRS implantation procedures, to assess its acute results postimplantation, and the changes experienced in the long-term until complete bioresorption has ensued. © 2016 Wiley Periodicals, Inc.

Optimisation of percutaneous coronary intervention: indispensables for bioresorbable scaffolds

INTRODUCTION

With new developments in percutaneous coronary intervention (PCI), such as the introduction of bioresorbable scaffolds (BRS), percutaneous treatment of coronary artery diseases has entered a new era. Without metallic remnants, BRSs appear able to overcome several limitations of the existing metallic stents and provide a physiologic treatment of coronary artery pathology.

AREAS COVERED

BRS have different mechanical properties compared to the traditional metallic stents that should be taken into account during their implantation. Lesion selection, device sizing and satisfied pre-dilatation should be implemented prudently. Although intravascular imaging is not mandatory for the implantation of BRSs it may have a value in optimizing device deployment assess final results and reduce the risk of device related adverse events such as re-stenosis, or scaffold thrombosis. This review aims to reveal the crucial points about the methods of optimization in each steps of BRS implantation. Expert commentary: The target lesions for BRS should be selected meticulously. Pre-dilatation, post-dilatation and intra-vascular imaging techniques should be implemented appropriately to avoid undesirable events after scaffold implantation.

A Comparison of Intravascular Imaging Modalities for Detection of Stent Struts in Acute Coronary Syndrome

BACKGROUND

We used optical coherence tomography (OCT) and intravascular ultrasound (IVUS) to assess the struts of implanted stents in patients with acute coronary syndrome (ACS).

METHODS

A totle of 10,756 stent struts were analyzed with OCT in 42 patients of ACS. Of them, both of IVUS and OCT imaging were performed in 33 patients. Appearance of stent struts was classified as well apposed, buried, malapposed, and nondetectable, and the number of stent struts were counted by OCT and IVUS was compared.

RESULTS

Most of stent struts were well apposed (78.1%, 8,407/10,756). However, malapposed struts were 5.6% (607/10,756), and 14.1% (1,514/10,756) of stent struts were buried by thrombus. The nondetectable struts were 2.11% (228/10,756) in ACS. 94.7% (216/228) of nondetectable stent struts were associated with red thrombus, and plaque prolapse was in 5.3% (12/228). The number of stent struts counted by OCT were larger than that of IVUS. The mean number of stent struts at the proximal and distal stent edges were 24 ± 6.57 in OCT, the stent struts IVUS counted were 20 ± 4.18 (P < 0.0001). Although the frequency of malapposed struts were similar 4.6% (376/8,248) in OCT versus 4.8% (369/7,674) in IVUS (P = 0.788). Stent struts were often buried by thrombus in ACS 15.2% (1,252/8,248) in OCT versus 9.7% (747/7,674) in IVUS; P = 0.006. The nondetectable struts were fewer in IVUS than OCT 0.2% (16/7,674) in IVUS versus 2.2% (187/8,248) in OCT; P < 0.0001.

CONCLUSION

Stent struts are frequently buried and nondetectable due to thrombi burden in ACS patients. Adequate thrombus removal and proper selection of the imaging device is warranted in ACS.

Intracoronary optical coherence tomography: a review of clinical applications

Optical coherence tomography (OCT) is a light-based technology that provides very high spatial resolution images. OCT has been initially employed as a research tool to investigate plaque morphology and stent strut coverage. The introduction of frequency domain OCT allowing fast image acquisition during a prolonged contrast injection via the guiding catheter has made OCT applicable for guidance of coronary interventions. In this manuscript, the various applications of OCT are reviewed, from assessment of plaque vulnerability and severity to characteristics of unstable lesions and thrombus burden to stent optimization and evaluation of late results.

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.

The relationship between post-stent strut apposition and follow-up strut coverage assessed by a contour plot optical coherence tomography analysis

OBJECTIVES

This study sought to evaluate the relationship between post-stent strut apposition and follow-up strut coverage using contour plot optical coherence tomographic analysis.

BACKGROUND

Tracking the fate of interested regions of struts at different time points has not been investigated.

METHODS

Post-intervention and 6-month follow-up optical coherence tomographic evaluations were performed in 82 patients treated with biolimus- (n = 37) or sirolimus-eluting stents (n = 45). Post-stent apposition was classified as embedded, apposed, or malapposed. For volumetric stent evaluation, the post-intervention strut-artery distance and the neointimal thickness at follow-up were measured as a function of the circumferential arc length and longitudinal stent length. Computer-generated contour plots of the strut-artery distance and neointimal thickness were compared.

RESULTS

The percentages of embedded and malapposed struts after intervention were 1.8% (Interquartile range [IQR]: 0.6% to 6.2%) and 2.3% (IQR: 0.5% to 5.2%), respectively. The percentages of uncovered and malapposed struts at 6 months were 16.0% (IQR: 7.4% to 33.3%) and 0% (IQR: 0% to 0.7%), respectively. The percentage of uncovered struts at 6 months varied significantly with post-stent strut apposition (0% [IQR: 0% to 11.4%] in embedded, 16.3% [IQR: 8.1% to 31.3%] in apposed, and 26.8% [IQR: 0% to 56.3%] in malapposed, p < 0.001 for all pairwise comparisons). In lesions without tissue prolapse, embedded struts were all covered (100% covered struts) compared with those with tissue prolapse (76.8% covered, p < 0.001).

CONCLUSIONS

The optical coherence tomography-guided optimization of stent strut apposition enhances strut coverage at follow-up. This comprehensive method for evaluating strut apposition may provide more useful information to understanding the serial changes in strut coverage. (Neointimal Coverage After Implantation of Biolimus Eluting Stent With Biodegradable Polymer: Optical Coherence Tomographic Assessment According to the Treatment of Dyslipidemia and Hypertension and the Types of Implanted Drug-Eluting Stents; NCT01502904).

Impact of strut-vessel distance and underlying plaque type on the resolution of acute strut malapposition: serial optimal coherence tomography analysis after everolimus-eluting stent implantation

The consequences of acute strut malapposition in everolimus-eluting stents (EES) are unknown. This study investigated the impact of strut-vessel (S-V) distance and plaque type underneath acute strut malapposition on the mid-term vessel response in EES. Twenty-nine patients (35 EES) underwent optical coherence tomography (OCT) immediately after percutaneous coronary intervention and at 8-month follow-up. S-V distance and plaque type (lipid, calcified, or fibrous) underneath acute strut malapposition were evaluated. Follow-up OCT classified acute strut malapposition as persistent or resolved. The S-V cutoff value for predicting resolved strut malapposition and the incidence of intra-stent thrombi were determined. Among 569 cases of acute strut malapposition, involving 29,168 struts, 139 (24.4 %) were persistent. Mean S-V distance was significantly longer in persistent than in resolved strut malapposition (600 ± 294 vs. 231 ± 95 μm; P < 0.0001). S-V distance ≤380 μm was the best cutoff value for predicting resolved strut malapposition (sensitivity 93.5 %, specificity 69.8 %, area under curve 0.878). Acute strut malapposition with S-V distance ≤380 μm remained persistent more frequently over lipid/calcified than over fibrous plaques (lipid: 13.4 %, calcified: 18.2 %, fibrous: 4.2 %; lipid vs. fibrous, P = 0.001; calcified vs. fibrous, P = 0.02). Intra-stent thrombi were more frequent in stents with ≥1 persistent strut malapposition than in those without [4/11 stents (36.3 %) vs. 0/24 (0 %); P = 0.006]. Lipid and calcified plaque, together with S-V distance, affect the resolution of acute strut malapposition in EES. Persistent strut malapposition is associated with the presence of thrombi at follow-up, which could be the substrate for late stent thrombosis.

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.

Optical coherence tomography guided PCI - initial experience at Apollo Health City, Jubilee Hills, Hyderabad

Background

The capability of OCT to examine the structure of the arterial wall before or after PCI is superior to those of other imaging modalities. Therefore the application of OCT during PCI seems logical and has the potential to enhance our performance during the PCI procedures.

Methods

OCT was performed in fifty-two patients out of which, 45 patients underwent PCI. Out of these 45 patients, in 25 patients both pre and post PCI OCT assessment was done. In 20 patients only post PCI OCT assessment was done. In seven patients PCI was not done due to nonsignificant obstruction, these seven patients were not included in final analysis.

Results

Over all OCT leads to management changes in 65% of the time it was used. Alteration of stent length was done in 56% of the cases when evaluated pre PCI. Alteration of stent diameter was done in 36% cases when evaluated pre PCI. Treatment of malapposition was done in 24% of total cases. Further balloon dilatation for vessel expansion was done in 15% of total cases. In one case left main stenting was done after proximal edge dissection.

Conclusion

OCT makes better visualization of plaque, thrombus, stent malapposition, dissection, plaque prolapse and helps in optimization of PCI results. More extensive, long-term studies will be needed to assess the prognostic implications of these findings.

Stent longitudinal strength assessed using point compression: insights from a second-generation, clinically related bench test

BACKGROUND

Stent longitudinal distortion, while infrequent, can lead to adverse clinical events. Our first bench comparison of susceptibility of different stent designs to distortion applied force to the entire circumference of the proximal stent hoop. The test increased understanding of stent design and led to recommendations for design change in some. Our second-generation test more closely mimics clinical scenarios by applying force to a point on the proximal hoop of a malapposed stent.

METHODS AND RESULTS

Each 3-mm-diameter stent was secured in a test apparatus so that its proximal 5 mm was malapposed in a 3.5-mm tube. An instron applied force to the proximal hoop of each of 5 examples of each of 6 stent designs using a narrow rod so that force applied and distance compressed could be measured. Hoops on the side of the force were pushed together, became malapposed, and obstructed the lumen. In addition, the proximal stent hoop tilted causing malapposition, the contralateral side of the stent from the applied force causing lumen obstruction.

CONCLUSIONS

This second-generation, more clinically relevant test showed the Biomatrix Flex was the most resistant to deformation and the Element the most easily deformed. The addition of more connectors between the proximal hoops in the Promus Premier design has reduced the potential for distortion when compared with the Element, so that distortion was similar to the Vision, Multi-Link 8, and Integrity designs. The test also provided insight into the way in which stents are likely to distort in clinical practice.

Intravascular ultrasound assessment of drug-eluting stent coverage of the coronary ostium and effect on outcomes

When stenting an ostial or proximal coronary lesion, 1 fundamental decision is whether to extend the proximal end of the stent into the aorta (in the case of the left main [LM] or right coronary ostium) or into the polygon of confluence of the LM (in the case of the left anterior descending [LAD] ostium). Complete angiographic and intravascular ultrasound data and 9-month follow-up angiographic and clinical data were available from 459 patients with 138 ostial lesions (angiographic diameter stenosis within the ostium of ≥50%) or 321 nonostial lesions in which the proximal end of the stent ended at or near the coronary ostium. Strut protrusion was more frequent in the LM than in the right or LAD ostium (68% vs 59% vs 53%, p = 0.010). The length of strut protrusion was 3.4 ± 1.7 mm in the LM ostium, 1.7 ± 1.0 mm in the LAD ostium, and 2.4 ± 1.4 mm in the right ostium (p = 0.001). In contrast, incomplete stent coverage of the ostium was similar among the LM, LAD, and right coronary artery (23% vs 33% vs 28%, p = 0.084) with a residual uncovered segment plaque burden of 42 ± 11%. Ostial restenosis was similar between the lesions with versus without strut protrusion (3.2% vs 2.3%, p = 0.775) and between the lesions with incomplete versus complete stent coverage of the ostium (2.4% vs 3.0%, p = 0.100). Ostial restenosis was seen in only 2 of 61 lesions (3.3%) with acute malapposition. In conclusion, when treating an ostial or proximal coronary artery lesion with a drug-eluting stent, the decision of whether to protrude the proximal end of the stent or leave the ostium uncovered does not appear to be critical.

Angiographic maximal luminal diameter and appropriate deployment of the everolimus-eluting bioresorbable vascular scaffold as assessed by optical coherence tomography: an ABSORB cohort B trial sub-study

AIMS

Bioresorbable vascular scaffolds (BVS) present different mechanical properties as compared to metallic platform stents. Therefore, the standard procedural technique to achieve appropriate deployment may differ.

METHODS AND RESULTS

Fifty-two lesions treated with a 3 x 18 mm BVS were imaged with optical coherence tomography (OCT) post-implantation and screened for parameters suggesting non-optimal deployment. These included minimal scaffold area (minSA)<5 mm², residual area stenosis (RAS)>20%, edge dissections, incomplete scaffold/strut apposition (ISA)>5% and scaffold pattern irregularities. The angiographic proximal and distal maximal lumen diameters (DMAX) were measured by quantitative coronary angiography. Based on the DMAX values, the population was divided into three groups: DMAX <2.5 mm (n=13), DMAX between 2.5-3.3 mm (n=30) and DMAX >3.3 mm (n=9). All three groups presented with similar pre-implantation angiographic characteristics except for the vessel size and were treated with similar balloon/artery ratios. The group with a DMAX <2.5 mm presented with a higher percentage of lesions with minSA <5 mm² (30.8% vs. 10.0% vs. 0%; p=0.08) and edge dissections (61.5% vs. 33.3% vs. 11.1%; p=0.05). Lesions with >5% of ISA were significantly higher in the group with DMAX >3.3 mm (7.7% vs. 36.7% vs. 66.7%; p=0.02). RAS >20% was similar between all groups (46.2 vs. 53.3 vs. 77.8%; p=0.47) and scaffold pattern irregularities were only documented in three cases.

CONCLUSIONS

BVS implantation guided with quantitative angiography may improve the OCT findings of optimal deployment. The clinical significance of these angiographic and OCT findings warranted long term follow-up of larger cohort of patients.

Optimization of stent deployment by intravascular ultrasound

Intravascular ultrasound (IVUS) is a useful diagnostic method that provides valuable information in addition to angiography regarding the coronary vessel lumen, dimensions, plaque burden, and characteristics. The major use of IVUS in coronary intervention is to guide interventional strategies and assess optimal stent deployment. Since the introduction of the drug-eluting stent (DES), concerns about restenosis have decreased. However, high-risk lesion subsets are being routinely treated with DESs, and the incidence of suboptimal results after stent deployment, such as stent underexpansion, incomplete stent apposition, edge dissection, geographic miss, and the risk of stent thrombosis, have correspondingly increased. Thus, optimization of stent deployment under IVUS guidance may be clinically important. In this review, we focus on the potential role of IVUS in stent optimization during percutaneous coronary intervention and its clinical benefits.

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.

Comprehensive intravascular ultrasound assessment of stent area and its impact on restenosis and adverse cardiac events in 403 patients with unprotected left main disease

BACKGROUND

We assessed the optimal intravascular ultrasound (IVUS) stent area to predict angiographic in-stent restenosis (ISR) after sirolimus-eluting stent implantation for unprotected left main coronary artery (LM) disease.

METHODS AND RESULTS

A total of 403 patients treated with single- or 2-stent strategies (crushing and T-stent) had immediate poststenting IVUS and 9-month follow-up angiography. Poststenting minimal stent area (MSA) was measured in each of 4 segments: ostial left anterior descending (LAD), ostial left circumflex (LCX) polygon of confluence (POC, confluence zone of LAD and LCX), and proximal LM above the POC. Overall, 46 (11.4%) showed angiographic restenosis at 9 months: 3 of 67 (4.5%) nonbifurcation lesions treated with a single-stent, 14 of 222 (6.3%) bifurcation lesions treated with single-stent crossover, and 29 of 114 (25.4%) of bifurcation lesions treated with 2 stents. The MSA cutoffs that best predicted ISR on a segmental basis were 5.0 mm(2) (ostial LCX ISR), 6.3 mm(2) (ostial LAD ISR), 7.2 mm(2) (ISR within the POC), and 8.2 mm(2) (ISR within the LM above the POC). Using these criteria, 133 (33.8%) had underexpansion of at least 1 segment. Angiographic ISR (at any location) was more frequent in lesions with underexpansion of at least 1 segment versus lesions with no underexpansion (24.1% versus 5.4%, P<0.001). Two-year major adverse coronary event-free survival rate was significantly lower in patients with underexpansion of at least 1 segment versus lesions with no underexpansion (90±3% versus 98±1%, log-rank P<0.001), and poststenting underexpansion was an independent predictor for major adverse cardiac events (adjusted hazard ratio, 5.56; 95% confidence interval, 1.99-15.49; P=0.001).

CONCLUSIONS

With these criteria, IVUS optimization during LMCA stenting procedures may improve clinical outcomes.

Assessment of drug-eluting stents and bioresorbable stents by grayscale IVUS and IVUS-based imaging modalities

Grayscale IVUS and IVUS-based imaging modalities during the last years have become useful in the assessment not only of drug eluting stent, but also of new bioresorbable vascular scaffolds. Although IVUS resolution is not sufficient for determining stent coverage (optical coherence tomography is the gold standard), serial IVUS can measure intimal hyperplasia, assess acute and late incomplete stent apposition, detect the presence and persistence of edge dissections, study edge effects and look for causes of restenosis and thrombosis. In addition other IVUS-based imaging modalities, such as IVUS-VH, iMAP or palpography, can be used to study the serial compositional and mechanical changes of the plaque behind stent struts and also to follow the bioresorption of the new bioresorbable scaffolds, analyzing the backscattering signal coming from the polymeric struts. This review details and evaluates grayscale IVUS and IVUS-based techniques findings in clinical trials, highlighting the usefulness of these imaging modalities in the study of drug eluting stents and bioresorbable vascular scaffold.

Optical coherence tomography: its value in intravascular diagnosis today

Optical coherence tomography is a recently developed high-resolution intravascular diagnostic technique. Initially, it was mainly used for characterizing atherosclerotic plaque because it served a number of functions, from identifying plaque with high lipid content to detecting macrophage accumulation, both of which are associated with plaque instability. Currently, there is growing interest in the value of optical coherence tomography in the area of coronary intervention, where the technique offers significant advantages over more widespread intravascular diagnostic techniques such as intravascular ultrasound: its higher resolution means that the vessel lumen diameter can be measured more precisely, periprocedural complications such microdissection of the coronary artery can be detected, stent apposition relative to the vessel wall can be optimized, neointimal hyperplasia can be detected after stent implantation, and neointimal thickness can be measured. It would therefore appear to be a very useful technique for interventional cardiologists. This review article considers the technical details of the technique and its applications, and compares it with other intravascular diagnostic techniques.

Incidence, Mechanisms, Predictors, and Clinical Impact of Acute and Late Stent Malapposition After Primary Intervention in Patients With Acute Myocardial Infarction

Background— The incidence and mechanisms of acute and late stent malapposition after primary stent implantation in ST-segment elevation myocardial infarction remain unclear.

Methods and Results— The Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial was a dual-arm, factorial, randomized trial comparing paclitaxel-eluting stents (PES) and otherwise equivalent bare metal stents (BMS) in ST-segment elevation myocardial infarction patients. The intravascular ultrasound substudy enrolled 241 patients with 263 native coronary lesions (201 PES, 62 BMS) with baseline and 13-month follow-up imaging. Postintervention acute stent malapposition (ASM) occurred in 34.3% PES- and 40.3% BMS-treated lesions. Of these, 39.1% PES- and 40.0% BMS-treated lesions resolved at follow-up, especially within the stent body (66.7%); complete resolution was accompanied by a reduction in external elastic membrane area. An ASM area >1.2 mm 2 best separated persistent from resolved ASM. At follow-up, a higher frequency of late stent malapposition was detected in PES-treated lesions (46.8%) mainly because of more late acquired stent malapposition (30.8%) compared with BMS-treated lesions. Late acquired stent malapposition area correlated to the decrease of peri-stent plaque in the subset of lesions without positive remodeling and only to change in external elastic membrane in the group with positive remodeling. Independent predictors of late acquired stent malapposition were plaque/thrombus protrusion (odds ratio, 5.60; 95% confidence interval [CI], 2.32 to 13.54) and PES use (odds ratio, 6.32; 95% CI, 2.15 to 18.62).

Conclusions— The incidence of ASM was similar in PES- and BMS-treated lesions, but late acquired stent malapposition was more common in PES-treated lesions. The reason for resolved ASM was negative remodeling, with larger ASM areas separating persistent from resolved ASM. Late acquired stent malapposition was due mainly to positive remodeling and plaque/thrombus resolution.

Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00433966.

Long-term impact of routinely detected early and late incomplete stent apposition: an integrated intravascular ultrasound analysis of the TAXUS IV, V, and VI and TAXUS ATLAS workhorse, long lesion, and direct stent studies

OBJECTIVES

We sought to determine the 2-year impact of early and late-acquired incomplete stent apposition (ISA) on clinical events.

BACKGROUND

The late clinical impact of early or late-acquired ISA in bare-metal stents (BMS) and TAXUS stents (Boston Scientific, Natick, Massachusetts) is debatable.

METHODS

We evaluated 1,580 patients enrolled in the intravascular ultrasound (IVUS) substudies of TAXUS IV, V, VI and TAXUS-ATLAS WH, LL, and DS trials.

RESULTS

There were 96 cases of early ISA in 26 (7.2%) BMS patients, 35 (9.7%) TAXUS Express patients (p = 0.28 vs. BMS), and 35 (7.3%) TAXUS Liberté patients (p = 0.21 vs. TAXUS Express, and p = 1.00 vs. BMS). Major adverse cardiovascular events were similar at 9 months in patients with early ISA versus control subjects with no ISA for BMS (3.8% vs. 15.2%, p = 0.13) and for TAXUS (11.6% vs. 8.8%, p = 0.45). There was no impact of early ISA on stent thrombosis. At 9-month follow-up, there were 36 cases of late-acquired ISA in 7 (2.7%) BMS patients, 17 (3.1%) patients with TAXUS slow-release (TAXUS Express or TAXUS Liberté), and 12 (15.4%) patients receiving TAXUS moderate-release. Over 2 ensuing years, major adverse cardiovascular events were similar in patients with late-acquired ISA versus control subjects with no ISA for BMS (14.3% vs. 7.9%, p = 0.54), TAXUS (overall, 8.3% vs. 8.1% p = 0.87), or TAXUS slow-release formulation (0% vs. 7.9%, p = 0.28). There was no impact of late-acquired ISA on stent thrombosis.

CONCLUSIONS

Neither routinely detected acute ISA nor routinely detected late-acquired ISA in BMS or TAXUS patients was associated with adverse clinical events over long-term follow-up.

Simple versus complex approaches to treating coronary bifurcation lesions: direct assessment of stent strut apposition by optical coherence tomography

INTRODUCTION AND OBJECTIVES

Stenting of coronary bifurcation lesions carries an increased risk of stent deformation and malapposition. Anatomical and pathological observations indicate that the high stent thrombosis rate in bifurcations is due to malapposition of stent struts.

METHODS

Strut apposition was assessed with optical coherence tomography (OCT) in bifurcation lesions treated either using the simple technique of stent implantation in the main vessel only or a complex technique (i.e. Culotte's). A strut was regarded as malapposed if the gap between its endoluminal surface and the vessel wall was greater than its thickness plus an OCT resolution error margin of 15 microm.

RESULTS

Simple and complex (i.e. Culotte's) approaches were used in 17 and 14 patients, respectively. Strut malapposition was significantly more frequent for the half of the bifurcation on same side as the vessel side branch (median, 46.1%; interquartile range [IQR], 35.3-62.5%) than for the half opposite the side branch (9.1%; IQR, 2.2-21.6%), the distal segment (7.5%; IQR, 2.3-20.2%) or the proximal segment (12.6%; IQR, 7.8-23.1%; P< .0001); the gap between strut and vessel wall in malapposed struts was significantly greater in the first segment than the others: 98 microm (IQR, 37-297 microm) vs. 31 microm (IQR, 13-74 microm), 49 microm (IQR, 20-100 microm) and 38 microm (IQR, 17-90 microm), respectively (P< .0001). Using the complex technique had no effect on the prevalence of strut malapposition in the four segments relative to the simple technique (P=.31) but was associated with a smaller gap in the proximal segment (47 microm vs. 60 microm; P=.0008).

CONCLUSIONS

In coronary bifurcation lesions, strut malapposition occurred most frequently and was most significant close to the side branch ostium. The use of Culotte's technique did not significantly increase the prevalence of strut malapposition compared with a simple technique.

Optical coherence tomography assessment of a new dedicated bifurcation stent

AIMS

Dedicated bifurcation stents should facilitate deployment and improve coverage of bifurcational lesions. We used optical coherence tomography (OCT) to assess bifurcation lesions treated with a dedicated stent implanted in the side branch (SB) in conjunction with drug eluting stents in the main vessel (MV) in a culotte-like fashion.

METHODS AND RESULTS

Nine patients treated with the Tryton stent underwent postprocedural OCT examination. Total percent of malapposed struts per patient was 18.1+/-8.7%. The longitudinal distribution of the percent of malapposed struts per patient showed that the prevalence of malapposed struts was significantly higher at the level of the bifurcation (33.3%), than in both the proximal segment and the distal segment (18.5% and 9.8%, respectively, p=0.011). When the bifurcation was divided into two halves (opposite SB and toward SB), the highest percent of malapposed struts was toward the SB (47.6%). Also the wall-strut distance for malapposed struts was significantly higher in the bifurcation half toward the SB than in the proximal and the distal segment.

CONCLUSIONS

Malapposed struts are frequent in bifurcations despite the use of a dedicated stent. The highest frequency and largest vessel wall-stent strut distance are observed in the bifurcation half toward the SB.

SPIRIT III JAPAN versus SPIRIT III USA: a comparative intravascular ultrasound analysis of the everolimus-eluting stent

The aim of this study was to evaluate the vascular response after everolimus-eluting stent (EES) implantation in the SPIRIT III Japan Registry (JAPAN) compared to EES implantation in the SPIRIT III United States (USA) trial using serial intravascular ultrasound (IVUS) analysis. Data were obtained from the JAPAN and the randomized EES arm of the USA trial. Serial (postprocedure and 8-month follow-up) IVUS analysis was available in 199 lesions (JAPAN 82, USA 117) of 183 patients (JAPAN 73, USA 110). Although no difference was observed in vessel size in the reference segment between the 2 groups, postprocedure minimum lumen area and stent volume index were significantly greater in the JAPAN arm (minimum lumen area 5.8 +/- 2.2 vs 5.1 +/- 1.5 mm(2), p = 0.03; stent volume index 7.0 +/- 2.4 vs 6.3 +/- 1.7 mm(3)/mm, p = 0.03). Postprocedure incomplete stent apposition (ISA) was less frequently observed in the JAPAN arm (15.9% vs 33.3%, p = 0.006), possibly related to higher maximum balloon pressure and/or more postdilatation without excess tissue prolapse or edge dissection. In the JAPAN arm, percent neointimal obstruction and maximum percent cross-sectional narrowing were significantly lower at 8-month follow-up (percent neointimal obstruction 3.5 +/- 4.2% vs 6.8 +/- 6.4%, p = 0.0004). Late acquired ISA was infrequent in the 2 arms. In conclusion, comparative IVUS analysis between the JAPAN and USA arms showed more optimal stent deployment in the JAPAN arm as evidenced by the lower incidence of postprocedure ISA and larger minimum lumen area after the procedure. Moreover, there was less neointimal hyperplasia in patients with EES implants from the JAPAN arm compared to the USA arm.

Comparison of sirolimus and paclitaxel-eluting stents for complex coronary lesions: an intravascular ultrasound study

BACKGROUND/AIMS

Recent intravascular ultrasound (IVUS) studies of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) have demonstrated a significant reduction in neointimal hyperplasia (NIH) based on simple coronary lesions. In this study, we evaluated the efficacy of SES and PES using IVUS in complex coronary lesions.

METHODS

Eighty-seven patients in whom 95 drug-eluting stents (66 SES and 29 PES) were implanted in complex coronary lesions were enrolled in this study. Case selection was based on the availability of IVUS and quantitative coronary angiographic (QCA) examinations at the index procedure and at follow-up. The neointimal volume index (volume/length: NIVI) and percent neointimal volume (% NIV) were calculated. The longitudinal length of stented segments without IVUS-detectable NIH was also evaluated.

RESULTS

The baseline patient demographics were similar between the SES and PES groups. At follow-up, no significant differences were observed in the vessel, plaque, or stent volume indices between the two groups. However, the NIVI and % NIV were significantly lower in the SES group (p<0.01). The longitudinal length of stented segments without IVUS-detectable NIH was significantly higher in the SES group (p<0.01). The net gain was significantly larger in the SES group (2.3+/-0.7 vs. 2.0x0.6 mm, p=0.025), while the rate of major adverse cardiac events was similar between the two groups.

CONCLUSIONS

Although SES showed significantly greater suppression of NIH at follow-up, both stents were highly effective at inhibiting NIH in complex coronary lesions.

Intravascular ultrasonography-guided stent angioplasty of an extracranial vertebral artery dissection

The authors report on a case of intravascular ultrasonography (IVUS)-guided stent angioplasty for iatrogenic extracranial vertebral artery (VA) dissection in a 49-year-old man after coil embolization for an unruptured aneurysm of the right posterior inferior cerebellar artery. Insignificant dissections occurred during the procedure. Postoperatively, the patient experienced gradually worsening posterior neck pain and headache, and follow-up angiography 8 months after the coil embolization revealed expansion of the dissection. The patient underwent stent angioplasty with IVUS guidance and his symptoms improved.

To the authors' knowledge, this is the first report of IVUS-guided stent angioplasty of an extracranial VA dissection. It was safe and feasible to treat extracranial VA dissections with stent placement under IVUS guidance. Intravascular environments are in real time with IVUS, and this technique is useful in the confirmation of a true lumen and evaluation of appropriate stent apposition. More clinical experience with this technique is necessary and mandatory, and devices with smaller diameters with improved trackability are essential for further introduction of IVUS into the field of endovascular neurosurgery.

Drug-eluting stents in the real world: how intravascular ultrasound can improve clinical outcome

Although the benefits of drug-eluting stents for the treatment of native coronary lesions in patients undergoing percutaneous coronary interventions have been demonstrated in multiple clinical trials, there remains concern about the risk of late stent thrombosis. The MATRIX registry, a prospective study designed to reflect clinical conditions, has enrolled a varied population of complex patients who have received the sirolimus-eluting stent (SES) and long-term dual antiplatelet therapy. Contributing to the low rate of stent thrombosis and other complications after SES deployment in this study is the routine use of intravascular ultrasound (IVUS) imaging before and after implantation at a high rate (38%). Important technical considerations for the IVUS operator include stent expansion, residual edge stenosis, and malapposition. Ensuring adequate stent dimensions and wall contact can contribute to successful outcomes in patients receiving SES.