Long-Term Follow-Up of Incomplete Stent Apposition in Patients Who Received Sirolimus-Eluting Stent for De Novo Coronary Lesions

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute coronary syndromes (ACS) in 2024

Primary Percutaneous Coronary Intervention (PCI) has significantly contributed to reducing the mortality of patients with ST-segment elevation myocardial infarction (STEMI) even in cardiogenic shock and is now the standard of care in most of Japanese institutions. The Task Force on Primary PCI of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) proposed an expert consensus document for the management of acute myocardial infarction (AMI) focusing on procedural aspects of primary PCI in 2018 and updated in 2022. Recently, the European Society of Cardiology (ESC) published the guidelines for the management of acute coronary syndrome in 2023. Major new updates in the 2023 ESC guideline include: (1) intravascular imaging should be considered to guide PCI (Class IIa); (2) timing of complete revascularization; (3) antiplatelet therapy in patient with high-bleeding risk. Reflecting rapid advances in the field, the Task Force on Primary PCI of the CVIT group has now proposed an updated expert consensus document for the management of ACS focusing on procedural aspects of primary PCI in 2024 version.

Incidence, risk factors, and clinical sequelae of incomplete stent apposition after sirolimus-eluting stent

Incomplete stent apposition has been documented after sirolimus-eluting stent implantation. However, its clinical sequelae remain controversial. To identify the incidence and its clinical consequences of ISA, IVUS was performed on 78 patients. In spite of well apposition immediately after the deployment, late stent malapposition occurred after 6-months follow-up. A total of 7 patients who received SES showed ISA. There were no significant differences in IVUS measurements between patients with or without ISA. However, there was an increase in external elastic membrane area in ISA group than non-ISA group (19.69 ± 3.50 vs. 15.05 ± 2.56 mm2, P<0.05). There were positive clinical events for ISA cases at 6-months clinical follow-up. Univariate and multivariable analyses indicated that hs-CRP, miR-21, and MMP-2 were risk factor for ISA. ISA was observed in 9% of patients after SES implantation, which was related to vessel positive remodeling. The incidence of MACEs in patients with ISA was higher than those without ISA. However, careful long-term follow-up remains to be clarified.

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) update 2022

Primary Percutaneous Coronary Intervention (PCI) has significantly contributed to reducing the mortality of patients with ST-segment elevation myocardial infarction (STEMI) even in cardiogenic shock and is now the standard of care in most of Japanese institutions. The Task Force on Primary PCI of the Japanese Association of Cardiovascular Interventional and Therapeutics (CVIT) society proposed an expert consensus document for the management of acute myocardial infarction (AMI) focusing on procedural aspects of primary PCI in 2018. Updated guidelines for the management of AMI were published by the European Society of Cardiology (ESC) in 2017 and 2020. Major changes in the guidelines for STEMI patients included: (1) radial access and drug-eluting stents (DES) over bare-metal stents (BMS) were recommended as a Class I indication, (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. In 2020, updated guidelines for Non-ST-Elevation Myocardial Infarction (NSTEMI) patients, the followings were changed: (1) an early invasive strategy within 24 h is recommended in patients with NSTEMI as a Class I indication, (2) complete revascularization in NSTEMI patients without cardiogenic shock is considered as Class IIa recommendation, and (3) in patients with atrial fibrillation following a short period of triple antithrombotic therapy, dual antithrombotic therapy (e.g., DOAC and single oral antiplatelet agent preferably clopidogrel) is recommended, with discontinuation of the antiplatelet agent after 6 to 12 months. Furthermore, an aspirin-free strategy after PCI has been investigated in several trials those have started to show the safety and efficacy. The Task Force on Primary PCI of the CVIT group has now proposed the updated expert consensus document for the management of AMI focusing on procedural aspects of primary PCI in 2022 version.

Healed Erosion: The Role of Pre-interventional Optical Coherence Tomography in a Patient Clinically Suspected of Having Unstable Angina with Coronary Spasm

A 46-year-old man complained of chest pain at rest for the past three months. His symptoms gradually exacerbated and were suspected of being due to unstable angina. A coronary angiogram revealed focal tight stenosis at the proximal left anterior descending coronary artery with gross spastic coronary findings. Optical coherence tomography (OCT) revealed layered low-intensity structures with microvessels and the accumulation of macrophages, which indicated progressive stenosis with multiple-layered organized thrombus caused by coronary erosion. We treated the stenosis using a drug-coated balloon instead of drug-eluting stents. There was no restenosis, and OCT revealed good plaque healing at follow-up. This case suggests that the pre-interventional OCT plaque morphology can have a positive impact on the revascularization strategy.

Paclitaxel-Coated Balloon Angioplasty Versus Drug-Eluting Stent in Acute Myocardial Infarction: The REVELATION Randomized Trial

OBJECTIVES

This study sought to assess the efficacy and safety of a drug-coated balloon (DCB) strategy versus drug-eluting stent (DES) in primary percutaneous coronary intervention for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

In primary percutaneous coronary intervention for STEMI, stenting has proved to be beneficial with regard to repeat revascularization, but not recurrent myocardial infarction or death, compared with balloon angioplasty alone. A strategy of DCB angioplasty without stenting might abolish the potential disadvantages of stent implantation while reducing the probability of restenosis observed in plain old balloon angioplasty.

METHODS

In the prospective, randomized, single-center REVELATION trial, we compared DCB with DES in patients presenting with STEMI. Patients with a new, nonseverely calcified culprit lesion in a native coronary artery and a residual stenosis of <50% after pre-dilatation were randomized to treatment with a DCB or DES. The primary endpoint was fractional flow reserve at 9 months, allowing for a functional measurement of the infarct-related lesion.

RESULTS

A total of 120 patients were included. At 9 months after enrolment, the mean fractional flow reserve value was 0.92 ± 0.05 in the DCB group (n = 35) and 0.91 ± 0.06 in the DES group (n = 38) (p = 0.27). One abrupt vessel closure requiring treatment occurred after treatment with DCB. Up to 9-months follow-up, 2 patients required nonurgent target lesion revascularization (1 in each group).

CONCLUSIONS

In the setting of STEMI, the DCB strategy was noninferior to DES in terms of fractional flow reserve assessed at 9 months. Furthermore, it seemed to be a safe and feasible strategy. (Revascularization With Paclitaxel-Coated Balloon Angioplasty Versus Drug-Eluting Stenting in Acute Myocardial Infarction [REVELATION]; NCT02219802).

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) in 2018

While primary percutaneous coronary intervention (PCI) has significantly contributed to improve the mortality in patients with ST segment elevation myocardial infarction even in cardiogenic shock, primary PCI is a standard of care in most of Japanese institutions. Whereas there are high numbers of available facilities providing primary PCI in Japan, there are no clear guidelines focusing on procedural aspect of the standardized care. Whilst updated guidelines for the management of acute myocardial infarction were recently published by European Society of Cardiology, the following major changes are indicated; (1) radial access and drug-eluting stent over bare metal stent were recommended as Class I indication, and (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. Although the primary PCI is consistently recommended in recent and previous guidelines, the device lag from Europe, the frequent usage of coronary imaging modalities in Japan, and the difference in available medical therapy or mechanical support may prevent direct application of European guidelines to Japanese population. The Task Force on Primary Percutaneous Coronary Intervention of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) has now proposed the expert consensus document for the management of acute myocardial infarction focusing on procedural aspect of primary PCI.

LumenRECON Guidewire: Pilot Study of a Novel, Nonimaging Technology for Accurate Vessel Sizing and Delivery of Therapy in Femoropopliteal Disease

BACKGROUND

Proper vessel sizing during endovascular interventions is crucial to avoid adverse procedural and clinical outcomes. LumenRECON (LR) is a novel, nonimaging, 0.035-inch wire-based technology that uses the physics-based principle of Ohm's law to provide a simple, real-time luminal size while also providing a platform for therapy delivery. This study evaluated the accuracy, reliability, and safety of the LR system in patients presenting for a femoropopliteal artery intervention.

METHODS AND RESULTS

This multicenter, prospective pilot study of 24 patients presenting for peripheral intervention compared LR measurements of femoropopliteal artery size to angiographic visual estimation, duplex ultrasound, quantitative angiography, and intravascular ultrasound. The primary effectiveness and safety end point was comparison against core laboratory adjudicated intravascular ultrasound values and major adverse events, respectively. Additional preclinical studies were also performed in vitro and in vivo in swine to determine the accuracy of the LR guidewire system. No intra- or postprocedure device-related adverse events occurred. A balloon or stent was successfully delivered in 12 patients (50%) over the LR wire. Differences in repeatability between successive LR measurements was 2.5±0.40% (R²=0.96) with no significant bias. Differences in measurements of LR to other modalities were 0.5±1.7%, 5.0±1.8%, -1.5±2.0%, and 6.8±3.4% for intravascular ultrasound core laboratory, quantitative angiography, angiographic, and duplex ultrasound, respectively.

CONCLUSIONS

This study demonstrates that through a physics-based principle, LR provides a real-time, safe, reproducible, and accurate vessel size of the femoropopliteal artery during intervention and can additionally serve as a conduit for therapy delivery over its wire-based platform.

Aneurysmal coronary artery disease: An overview

Aneurysmal coronary artery disease (ACAD) comprises both coronary artery aneurysms (CAA) and coronary artery ectasia (CAE). The reported prevalence of ACAD varies widely from 0.2 to 10%, with male predominance and a predilection for the right coronary artery (RCA). Atherosclerosis is the commonest cause of ACAD in adults, while Kawasaki disease is the commonest cause in children and adolescents, as well as in the Far East. Most patients are asymptomatic, but when symptoms do exist, they are usually related to myocardial ischemia. Coronary angiography is the mainstay of diagnosis, but follow up is best achieved using noninvasive imaging that does not involve exposure to radiation. The optimal management strategy in patients with ACAD remains controversial. Medical therapy is indicated for the vast majority of patients and includes antiplatelets and/or anticoagulants. Covered stents effectively limit further expansion of the affected coronary segments. Surgical ligation, resection, and coronary artery bypass grafting are appropriate for large lesions and for associated obstructive coronary artery disease.

Observation of Neointimal Coverage Around the Aneurysm Neck After Stent-Assisted Coil Embolization by Optical Frequency Domain Imaging: Technical Case Report

BACKGROUND AND IMPORTANCE: Stent-assisted coil embolization has been established as a treatment option for wide-necked or complex aneurysms. However, concerns have been raised about the incidence of thromboembolic complications, which is higher for coil embolization without stent assistance. Long-term antiplatelet therapy is necessary to prevent acute or delayed ischemic events potentially associated with incomplete stent apposition after treatment with stent-assisted coil embolization. Optical frequency domain imaging (OFDI) provides excellent-resolution images of intraluminal structures, allowing evaluation of the outcomes of stent-assisted procedures in terms of stent apposition and neointimal coverage. We here describe the novel use of OFDI for the observation of intravascular tissue formation after stent-assisted coil embolization.

CLINICAL PRESENTATION: Two patients were treated with stent-assisted coil embolization for unruptured vertebral artery aneurysm. At the 1- or 2-yr follow-up visit, routine angiography followed by OFDI were performed to evaluate neointimal coverage of the stent strut and stent apposition to the vascular wall. OFDI enabled clear visualization of the vessel wall structures and demonstrated complete coverage of the stent struts as well as full stent wall apposition in 1 patient and incomplete coverage near the aneurism neck as well as mallaposition of some struts in the other patient.

CONCLUSION: OFDI represents a feasible modality for the evaluation of intracranial vasculature and the outcomes of stent-assisted coil embolization in terms of intimal healing of aneurysms, stent-vessel interactions, and neointimal coverage of the stent. Such information is helpful in determining the duration of antiplatelet therapy after stent-assisted coil embolization.

Drug deposition in coronary arteries with overlapping drug-eluting stents

Drug-eluting stents are accepted as mainstream endovascular therapy, yet concerns for their safety may be under-appreciated. While failure from restenosis has dropped to below 5%, the risk of stent thrombosis and associated mortality remain relatively high. Further optimization of drug release is required to minimize thrombosis risk while maintaining therapeutic dose. The complex three-dimensional geometry of deployed stents together with the combination of diffusive and advective drug transport render an intuitive understanding of the situation exceedingly difficult. In situations such as this, computational modeling has proven essential, helping define the limits of efficacy, determine the mode and mechanism of drug release, and identify alternatives to avoid toxicity. A particularly challenging conformation is encountered in coronary arteries with overlapping stents. To study hemodynamics and drug deposition in such vessels we combined high-resolution, multi-scale ex vivo computed tomography with a flow and mass transfer computational model. This approach ensures high geometric fidelity and precise, simultaneous calculation of blood flow velocity, shear stress and drug distribution. Our calculations show that drug uptake by the arterial tissue is dependent both on the patterns of flow disruption near the wall, as well as on the relative positioning of drug-eluting struts. Overlapping stent struts lead to localized peaks of drug concentration that may increase the risk of thrombosis. Such peaks could be avoided by anisotropic stent structure or asymmetric drug release designed to yield homogeneous drug distribution along the coronary artery and, at the least, suggest that these issues need to remain in the forefront of consideration in clinical practice.

Successful treatment of very late drug-eluting stent thrombosis using bare-metal stent evaluated using intravascular ultrasound and optical frequency domain imaging

A 65-year-old man who underwent percutaneous coronary intervention with sirolimus-eluting stents (SESs) 2 years ago was admitted with recurrent acute chest pain. Coronary angiography showed thrombotic occlusion within the SESs. After aspiration thrombectomy, multi-focal peri-stent contrast staining (PSS) was observed. Optical frequency domain imaging (OFDI) showed intracoronary thrombus, incomplete stent apposition (ISA), and multiple inter-strut hollows. Intravascular ultrasound (IVUS) images showed positive vessel remodeling. We deployed bare-metal stents in the SESs. Follow-up angiography showed no in-stent restenosis or PSS. OFDI showed well-covered stent surface with homogeneous neointima, without ISA. Additionally, IVUS images showed that the vessel remodeling had not worsened.

Safety and feasibility of a PAclitaxel-eluting balloon angioplasty in Primary Percutaneous coronary intervention in Amsterdam (PAPPA): one-year clinical outcome of a pilot study

AIMS

In primary percutaneous coronary intervention (PPCI), stenting has been shown to reduce the need for repeat target lesion revascularisation (TLR) compared to balloon angioplasty alone, but did not result in a reduction of recurrent myocardial infarction (MI) or cardiac death. Meanwhile, stent-related adverse events such as stent thrombosis continue to be of concern. Our aim was to evaluate the safety and feasibility of drug- coated balloon (DCB) angioplasty without stenting in PPCI.

METHODS AND RESULTS

One hundred patients presenting with ST-elevation MI were prospectively enrolled in this pilot study. They underwent PPCI with DCB angioplasty; additional stenting was allowed only in case of type C to F coronary dissection or residual stenosis >50%. All patients were treated with i.v. bivalirudin. The primary endpoint was the composite of cardiac death, recurrent MI and TLR. A total of 59 patients received treatment with DCB angioplasty alone, whereas additional stenting was required in 41 patients. One-year clinical follow-up was completed in 98 patients. A total of five major adverse cardiac events were reported (5%). Cardiac death was seen in two patients, while three patients underwent TLR.

CONCLUSIONS

This first study of a DCB angioplasty-only strategy in the setting of PPCI showed good one-year clinical results.

Evolving management of patients treated by drug-eluting stent: prevention of late events

SUMMARY

Drug eluting stents (DES) were introduced in clinical practice to overcome the problem of in-stent restenosis (ISR) that limited the overall efficacy of percutaneous coronary revascularization with bare metal stent (BMS). Long-term outcome data confirm a sustained benefit of DES as compared with BMS. However, this benefit is mainly evident in the first year of follow-up. Indeed, DES-related events may extend over this time, due to late events (late ISR and/or very late stent thrombosis). Prevention of late failure of DES may become a specific therapeutic target.

Comparison of vascular response to the everolimus-eluting stent versus the paclitaxel-eluting stent: intravascular ultrasound results from the SPIRIT III trial

AIMS

The purpose of this study was to investigate the vascular response of the everolimus-eluting stent (EES) compared with the paclitaxel-eluting stent (PES) using serial intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the SPIRIT III trial, a multicentre, 2:1 randomised, controlled study comparing EES and PES in de novo native coronary artery lesions. IVUS images were eligible for volumetric analysis at eight-month follow-up in 158 lesions (EES: 113, PES: 45). At eight months, EES had a smaller neointimal volume index (VI: mm3/mm) (EES: 0.4±0.4 vs. PES: 0.8±0.8 mm3/mm, p=0.002) and also a smaller % neointimal obstruction (EES: 7.1±6.7% vs. PES: 11.1±10.5%, p=0.005) compared with PES. While there was no significant change in vessel VI with EES, there was a significant increase in vessel VI in PES during eight-month follow-up (EES: 0.1±1.2 vs. PES: 1.2±0.8 mm3/mm, p=0.001). There were no statistical differences in the frequency of edge dissection or incomplete stent apposition between the two groups.

CONCLUSIONS

Detailed IVUS analysis confirmed significantly less neointimal hyperplasia with EES compared with PES. While there was no increase in vessel volume with EES during the eight-month follow-up period, vessel enlargement was seen at the stented segment in PES.

Recurrence of late incomplete stent apposition after very late stent thrombosis following drug-eluting stent implantation

A 48-year old man was admitted to our hospital because of chest pain 20 months after sirolimus-eluting stent implantation to his left anterior descending coronary artery. A coronary angiogram showed a thrombosis of the stented segment, which was successfully treated with bare-metal stent implantation. One month later, optical coherence tomography (OCT) demonstrated late-acquired incomplete stent apposition (ISA) in the stented segment. Additional dilatation was performed using a 4.5 mm balloon. Eleven months later, OCT and intravascular ultrasound images revealed recurrent ISA as a result of progressive vessel remodeling. Serial observation of the stented segment with late-acquired ISA is necessary to understand the natural course of late-acquired ISA and to establish a therapeutic strategy for late-acquired ISA after drug-eluting stent implantation.

Impact of positive peri-stent vascular remodeling after sirolimus-eluting and paclitaxel-eluting stent implantation on 5-year clinical outcomes: intravascular ultrasound analysis from the Poststent Optimal Stent Expansion Trial multicenter randomized trial

BACKGROUND

Positive peri-stent vascular remodeling (PPVR) after drug-eluting stent (DES) implantation is an important mechanism of late-acquired stent malapposition (LASM).

METHODS AND RESULTS

A total of 226 patients (sirolimus-eluting stent [SES], n=105; paclitaxel-eluting stent [PES], n=121) from the Poststent Optimal Stent Expansion Trial who underwent a post-intervention and 9-month follow-up intravascular ultrasound were followed clinically for 5 years. PPVR was arbitrarily defined as a >10% increase in the external elastic membrane volume index at follow-up. PPVR and LASM occurred more frequently with SESs than with PESs. The 5-year rate of major adverse cardiac events was lower with SES than with PES (10.7% vs. 23.2%, P=0.002). The late and very late stent thrombosis (ST) rate was similar between the 2 DES types, but it was higher in patients with PPVR than in those without PPVR (8.8% vs. 1.3%, P=0.009) regardless of the DES type. Early discontinuation (<1 year) of dual antiplatelet therapy (DAPT; hazard ratio [HR], 24.14; 95% confidence interval [CI]: 4.90-118.87; P<0.001), PPVR (HR, 14.94; 95%CI: 1.85-120.46; P=0.011), LASM (HR, 8.01; 95%CI: 1.93-33.16; P=0.004), and stent length (HR, 1.14; 95%CI: 0.98-1.32 per mm; P=0.078) were associated with increased risk of late and very late ST.

CONCLUSIONS

PPVR and LASM development after DES implantation, along with early discontinuation of DAPT and longer stent length, are important risk factors of late and very late ST.

Relationship between stent malapposition and incomplete neointimal coverage after drug-eluting stent implantation

BACKGROUND

Using optical coherence tomography (OCT), we evaluated the relationship between malapposed and uncovered struts following implantation of drug-eluting stents (DESs).

METHODS

A total of 271 patients with 306 lesions who underwent DES implantation and follow-up OCT were included in the study. The lesions were grouped based on the presence of malapposition and then by the median value of the percentage of malapposed struts (1.3%) to produce 3 groups: lesions without malapposition (group I, n = 232) and those with percentage of malapposed struts <1.3% (group II, n = 37) or ≥1.3% (group III, n = 37). Percentages of malapposed and uncovered struts were calculated as percent ratio of malapposed or uncovered to total struts in the defined cross-sections, respectively. We compared percentage of uncovered struts in all analyzable struts and in the residual struts without malapposed segments among the 3 groups.

RESULTS

Group III showed a significantly larger percentage of uncovered struts among all the struts (group I, 3.7 ± 6.4 vs. II, 5.5 ± 5.6 vs. III, 17.6 ± 15.9%, P < 0.001) and among residual struts without malapposed segments (3.7 ± 6.4 vs. 5.2 ± 5.7 vs. 15.0 ± 14.4%, respectively, P < 0.001). There was a significant correlation between malapposed and uncovered struts in group III (r = 0.393, P = 0.016), but not in group II (r =-0.007, P = 0.965) among residual struts without malapposed segments.

CONCLUSION

The percentage of uncovered DES struts was quite different depending on the presence and extent of malapposed struts.

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.

Comparison of vascular remodeling in patients treated with sirolimus-versus zotarolimus-eluting stent following acute myocardial infarction

BACKGROUND

The differences in the vascular response to stent implantation or in the incidence of late acquired stent malapposition among different types of drug-eluting stents are not well known in patients with acute myocardial infarction (MI).

HYPOTHESIS

The pattern of vascular remodeling and degree of neointimal proliferation were different depending on the different types of drug-eluting stents.

METHODS

This study used intravascular ultrasound (IVUS) to investigate vascular remodeling in patients treated with implantation of sirolimus-eluting stents (SESs) vs zotarolimus-eluting stents (ZESs) following acute MI. The study population consisted of 100 patients with acute MI who were treated either with SES (n = 41) or ZES (n = 59) and underwent both poststenting and 9-month follow-up IVUS examination. Serial vascular changes surrounding stented segments were compared between SES- and ZES-treated lesions.

RESULTS

Percentage of neointimal volume obstruction at follow-up was significantly smaller in SES-treated compared to ZES-treated lesions (2.8 ± 7.1% vs 18.1 ± 15.7%, respectively; P < 0.001). However, positive vascular remodeling, which was defined as greater than 10% increase in external elastic membrane volume index (31.7% vs 10.2%, respectively, P = 0.007), and late acquired stent malapposition (12.0% vs 0%, respectively, P = 0.006 ) occurred more frequently in SES-treated than in ZES-treated lesions.

CONCLUSIONS

The pattern of vascular remodeling, including positive remodeling, late acquired stent malapposition, and degree of neointimal proliferation might be different depending on the different types of drug-eluting stents in patients with acute MI.

Vascular ultrasound for atherosclerosis imaging

Cardiovascular disease is a leading cause of death in the Western world. Therefore, detection and quantification of atherosclerotic disease is of paramount importance to monitor treatment and possible prevention of acute events. Vascular ultrasound is an excellent technique to assess the geometry of vessel walls and plaques. The high temporal as well as spatial resolution allows quantification of luminal area and plaque size and volume. While carotid arteries can be imaged non-invasively, scanning of coronary arteries requires invasive intravascular catheters. Both techniques have already demonstrated their clinical applicability. Using linear array technology, detection of disease as well as monitoring of pharmaceutical treatment in carotid arteries are feasible. Data acquired with intravascular ultrasound catheters have proved to be especially beneficial in understanding the development of atherosclerotic disease in coronary arteries. With the introduction of vascular elastography not only the geometry of plaques but also the risk for rupture of plaques might be identified. These so-called vulnerable plaques are frequently not flow-limiting and rupture of these plaques is responsible for the majority of cerebral and cardiac ischaemic events. Intravascular ultrasound elastography studies have demonstrated a high correlation between high strain and vulnerable plaque features, both ex vivo and in vivo. Additionally, pharmaceutical intervention could be monitored using this technique. Non-invasive vascular elastography has recently been developed for carotid applications by using compound scanning. Validation and initial clinical evaluation is currently being performed. Since abundance of vasa vasorum (VV) is correlated with vulnerable plaque development, quantification of VV might be a unique tool to even prevent this from happening. Using ultrasound contrast agents, it has been demonstrated that VV can be identified and quantified. Although far from routine clinical application, non-invasive and intravascular ultrasound VV imaging might pave the road to prevent atherosclerotic disease in an early phase. This paper reviews the conventional vascular ultrasound techniques as well as vascular ultrasound strain and vascular ultrasound VV imaging.

Parent vessel size and curvature strongly influence risk of incomplete stent apposition in enterprise intracranial aneurysm stent coiling

BACKGROUND AND PURPOSE

Flexible microstents, such as the closed-cell EN, have facilitated adjunctive coiling of intracranial aneurysms. Little data are available on the ability of the stent struts to maintain vessel-wall apposition once deployed in the tortuous cerebral vasculature and the prevalence of ISA. The purpose of this study was to evaluate the relationship between geometric features of the parent vessel at the stent deployment site and prevalence of ISA.

MATERIALS AND METHODS

Postprocedural 3T-MRA was performed in a cohort of 39 patients undergoing EN stent-assisted intracranial aneurysm coiling. 3T-MRA was analyzed for the presence of ISA and supplemented by angiographic C-arm FPCT (DynaCT). Parent vessel diameter, curvature radius, and stent-subtended arc angle were measured at the site of deployment and analyzed for prediction of ISA in the ICA.

RESULTS

3T-MRA uncovered a unique crescent flow pattern (CS) outside the EN struts, which was confirmed by FPCT to indicate ISA resulting from EN crimping. ISA was detected on 3T-MRA in 19/39 patients (49%). Univariate analysis revealed ISA in the ICA to correlate with a large stent-subtended angle, a small curvature radius, and a large diameter but not stent length or jailing versus a sequential technique. Multivariate analysis identified ISA to correlate with vessel-curvature radius (OR, 253; P = .009), stent-subtended angle (OR, 225; P = .005), and parent vessel diameter (OR, 8.49; P = .044).

CONCLUSIONS

In this study, ISA was detectable by 3T-MRA in a significant proportion of patients undergoing EN stent-assisted coiling of ICA aneurysms in a vessel geometry- and stent-deployment location-dependent manner. This characteristic of EN coiling at this potentially tortuous location should be taken into account when selecting an endovascular strategy.

Impact of Polymer Formulations on Neointimal Proliferation After Zotarolimus-Eluting Stent With Different Polymers

Background—

Polymer formulation may affect the efficacy of drug-eluting stents. Resolute, Endeavor, and ZoMaxx are zotarolimus-eluting stents with different stent platforms and different polymer coatings and have been tested in clinical trials. The aim of this analysis was to compare the efficacy of zotarolimus-eluting stents with different polymers.

Methods and Results—

Data were obtained from the first-in man trial or first randomized trials of each stent, The Clinical RESpOnse EvaLUation of the MedTronic Endeavor CR ABT-578 Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (RESOLUTE), Randomized Controlled Trial to Evaluate the Safety and Efficacy of the Medtronic AVE ABT-578 Eluting Driver Coronary Stent in De Novo Native Coronary Artery Lesions (ENDEAVOR II), and ZoMaxx I trials. Follow-up intravascular ultrasound analyses (8 to 9 months of follow-up) were possible in 353 patients (Resolute: 88, Endeavor: 98, ZoMaxx: 82, Driver: 85). Volume index (volume/stent length) was obtained for vessel, stent, lumen, peristent plaque, and neointima. Cross-sectional narrowing was defined as neointimal area divided by stent area (%). Neointima-free frame ratio was calculated as the number of frames without intravascular ultrasound–detectable neointima divided by the total number of frames within the stent. At baseline, vessel, lumen, and peristent plaque volume index were not significantly different among the 4 stent groups. At follow-up, percent neointimal obstruction was significantly lower in Resolute compared with Endeavor, ZoMaxx, and Driver (Resolute: 3.7±4.0, Endeavor: 17.5±10.1, ZoMaxx: 14.6±8.1, Driver: 29.4±17.2%; P <0.001). Greater maximum cross-sectional narrowing and higher neointima-free frame ratio, suggesting less neointimal coverage, were observed in Resolute compared with other stent groups. Multiple regression analysis confirmed that the biodurable polymer used in Resolute independently correlated with neointimal suppression among 3 zotarolimus-eluting stents.

Conclusions—

The different polymer formulations significantly affect the relative amount of neointima for zotarolimus-eluting stents.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00248079.

Optical coherence tomography: a new imaging modality for plaque characterization and stent implantation

Optical coherence tomography (OCT) is a novel, catheter-based, invasive imaging system based on near-infrared light with high image resolution (15-20 μm). The system allows for unparalleled imaging of the coronary artery lumen, plaque characterization, assessment of coronary stent strut apposition, neointimal coverage, vascular proliferative response, complications such as focal dissection or thrombus formation, and insight into the time course of stent endothelization. This review will describe the currently available developments in OCT technology and its application in both the clinical and research arenas.

Incidence and natural history of coronary artery aneurysm developing after drug-eluting stent implantation

AIMS

There is a growing concern about the occurrence of coronary artery aneurysms (CAAs) after drug-eluting stent (DES) implantation and their long-term course. We assessed the occurrence and the factors affecting the long-term outcome of DES-associated CAA.

METHODS AND RESULTS

We analyzed 3,612 consecutive patients (4,419 lesions) who underwent follow-up angiography after DES implantation. All 34 CAAs (0.76% per lesion) in 29 patients (0.8% per patient) were detected at follow-up, and the mean elapsed time from DES implantation to CAA diagnosis was 414 ± 213 days. Angiographically, CAAs developed almost exclusively in complex (type B2/C) de novo lesions (30 [88.2%] of 34 lesions), and lesion length was significantly greater in patients with CAA than without CAA (26.9 ± 9.03 vs 23.1 ± 7.14 mm; P = .004). Myocardial infarction with stent thrombosis occurred in 5 patients with CAA (17.2%), 4 of whom were on aspirin only without clopidogrel.

CONCLUSION

Although CAAs rarely develop after DES implantation and show mostly favorable clinical courses, long-term maintenance of clopidogrel therapy might be required to minimize occurrence of adverse clinical events resulting from stent thrombosis.

Incomplete stent apposition and delayed tissue coverage are more frequent in drug-eluting stents implanted during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction than in drug-eluting stents implanted for stable/unstable angina: insights from optical coherence tomography

OBJECTIVES

The aim of this study was to compare the frequency of incomplete stent apposition (ISA) and struts not covered by tissue at long-term follow-up (as assessed by optical coherence tomography [OCT]) in drug-eluting stents (DES) implanted during primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) versus DES implanted for unstable and stable angina.

BACKGROUND

Incomplete stent apposition and the absence of strut endothelialization might be linked to stent thrombosis. DES implanted for STEMI might have a higher risk of thrombosis.

METHODS

Consecutive patients in whom OCT was performed at least 6 months after DES implantation were included in the study. Stent struts were classified on the basis of the presence or absence of ISA and tissue coverage.

RESULTS

Forty-seven lesions in 43 patients (1,356 frames, 10,140 struts) were analyzed (49% stable angina, 17% unstable angina, 34% STEMI). Median follow-up time was 9 (range 7 to 72) months. Drug-eluting stents implanted during primary PCI presented ISA more often than DES implanted in stable/unstable angina patients (75% vs. 25.8%, p = 0.001). The frequency of uncovered struts was also higher in the STEMI group (93.8% vs. 67.7%, p = 0.048). On multivariate analysis, DES implantation in STEMI was the only independent predictor of ISA (odds ratio: 9.8, 95% confidence interval: 2.4 to 40.4, p = 0.002) and the presence of uncovered struts at follow-up (odds ratio: 9.5, 95% confidence interval: 1.0 to 90.3, p = 0.049).

CONCLUSIONS

DES implanted for STEMI had a higher frequency of incompletely apposed struts and uncovered struts as assessed by OCT at follow-up. DES implantation during primary PCI in STEMI was an independent predictor of ISA and the presence of uncovered struts at follow-up.

Comparison of vascular response to zotarolimus-eluting stent vs paclitaxel-eluting stent implantation: pooled IVUS results from the ZoMaxx I and II trials

BACKGROUND

The ZoMaxx I and II trials were randomized controlled studies of the zotarolimus-eluting, phosphorylcholine-coated, TriMaxx stent for the treatment of de novo coronary lesions. The aim of this study was to compare the vessel response between zotarolimus- (ZES) and paclitaxel-eluting stents (PES) using intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the ZoMaxx I and II trials, in which a standard IVUS parameter was available in 263 cases (baseline and 9-months follow up). Neointima-free frame ratio was calculated as the number of frames without IVUS-detectable neointima divided by the total number of frames within the stent. While an increase in vessel and plaque was observed in PES from baseline to follow up, there was no significant change in ZES. At follow up, % neointimal obstruction was significantly higher (15.4 ± 8.8% vs 11.3 ± 9.7%), and minimum lumen area at follow up was significantly smaller in ZES compared to PES. However, the incidence of IVUS-defined restenosis (maximum cross-sectional narrowing >60%) was similar in the 2 groups (3.2% vs 6.7%). Neointima-free frame ratio was significantly lower in ZES. There were 5 cases of late incomplete stent apposition in PES and none in ZES.

CONCLUSIONS

These IVUS results demonstrate a similar incidence of severe narrowing between these 2 DES. There was a moderate increase in neointimal hyperplasia that was associated with a greater extent of neointimal coverage in ZES compared with PES.

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.

Late and very late drug-eluting stent malapposition: serial 2-year quantitative IVUS analysis

BACKGROUND

The long-term natural history of acquired malapposition continues to be the subject of debate.

METHODS AND RESULTS

Using volumetric intravascular ultrasound analyses, we evaluated serial (poststenting, 6-month, and 2-year follow-up) changes in drug-eluting stent-treated vascular segments with acquired malapposition. External elastic membrane, stent, lumen, malapposition, and peristent plaque+media (P+M=external elastic membrane -stent- malapposition) areas were measured; and volumes were calculated and divided by stent length (normalized volume). Among 250 lesions in which complete serial intravascular ultrasound data were available, stent malapposition was identified in 19 lesions (7.6%) at 6 months, and an additional 13 malapposition lesions were newly detected at 2 years (5.2%). Because no malapposition sites resolved, the malapposition rate at 2 years was 12.8%. Malapposition areas and volumes were correlated to the increases in external elastic membrane (positive remodeling) throughout the study period, from immediately after stenting to 6 months and from 6 months to 2 years, both in the group that developed malapposition at 6 months and in the group that developed malapposition at 2 years. Clinical follow-up beyond the 2 year intravascular ultrasound study was done in all patients. Overall, there were 2 cardiac deaths and 1 noncardiac death. Two patients presented with acute myocardial infarction associated with very late stent thrombosis (1 definite stent thrombosis, 1 probable stent thrombosis). Three patients underwent repeat revascularization owing to in-stent restenosis developed after the 2-year follow-up.

CONCLUSIONS

Expansive vascular remodeling may play a role in the development and dynamic progression of acquired drug-eluting stent malapposition, not only during the first 6 months after implantation but thereafter.

Long-term vascular changes after drug-eluting stent implantation assessed by serial volumetric intravascular ultrasound analysis

Using serial volumetric intravascular ultrasonography, we evaluated the predictors of late intimal hyperplasia (IH) increases after drug-eluting stent implantation. All eligible patients who underwent 6-month angiography without visual restenosis were requested to undergo a 2-year follow-up examination. Complete serial (after stenting and early [6-month], and late [2-year] follow-up) angiographic and intravascular ultrasound data were available for 135 patients with 143 lesions: 99 sirolimus-eluting stents and 44 paclitaxel-eluting stents. The external elastic membrane, stent, lumen, and peri-stent plaque volumes (external elastic membrane minus stent) were normalized by stent length. The percentage of IH volume was calculated as IH volume/stent volume x 100. The early reduction in the minimum lumen area was greater than the late reduction in the minimum lumen area (-0.8 +/- 0.8 vs -0.2 +/- 0.5 mm(2), p <0.001). A progressive increase occurred in the percentage of IH volume: 8.1 +/- 7.1% from baseline to 6 months and 2.4 +/- 3.9% from 6 months to 2 years (p <0.001, between the early and late increases in the percentage of IH). The use of paclitaxel-eluting stents was the only independent predictor for the percentage of IH volume at 6 months (beta = 0.419, p <0.001). The use of paclitaxel-eluting stents (beta = 0.365, p <0.001, 95% confidence interval 3.7 to 9.7) and the post-stenting normalized plaque and media volume (beta = 0.195, p = 0.020, 95% confidence interval 0.1 to 1.6) were the only independent predictors for the percentage of IH volume at 2 years. However, when the percentage of IH at 6 months was forced into the model, the percentage of IH at 6 months and the post-stenting normalized plaque and media volume, not paclitaxel-eluting stent use, predicted the 2-year percentage of IH. In conclusion, although IH continued to increase beyond 6 months, the growth rate of intima and luminal loss attenuated with time.

Extensive Late-Acquired Incomplete Stent Apposition After Sirolimus-Eluting Stent Implantation

Late-acquired incomplete stent apposition (ISA) is frequently observed after drug-eluting stent (DES) implantation. Most incidences of late-acquired ISA induced by positive vascular remodeling were of the focal type and occurred in a single vessel. We present an unusual case of a 45-year-old male subject diagnosed with late-acquired ISA that occurred in multiple vessels.

Clinical outcomes after sirolimus-eluting, paclitaxel-eluting, and bare metal stents (from the first phase of the prospective multicenter German DES.DE Registry)

The prospective multicenter German Drug-Eluting Stent (DES.DE) registry is an observational study to analyze and evaluate the therapeutic principle of the differential drug-eluting stents (sirolimus- and paclitaxel-eluting stents) and bare metal stents under real world conditions in the context of the German healthcare system. The baseline clinical and angiographic characteristics and follow-up events for 1 year were recorded for all enrolled patients. In addition, a health economics assessment was performed at 3, 6, 9, and 12 months after initial stent placement. The composite of death, myocardial infarction, and stroke, defined as major adverse cardiac and cerebrovascular events, and target vessel revascularization were used as the primary objectives. From October 2005 to October 2006, 6,384 patients were enrolled (sirolimus-eluting stents, n = 2,137; paclitaxel-eluting stents, n = 2,740; bare metal stents, n = 485) at 98 Deutsches Drug-Eluting Stent Register sites. With similar baseline clinical and descriptive morphology of coronary artery disease between both drug-eluting stent groups, no differences were present at 1 year of follow-up in the rates of overall mortality (3.8% vs 4.1%), target vessel revascularization (10.4% vs 10.4%), overall stent thrombosis (3.6% vs 3.8%), and major adverse cardiac and cerebrovascular events (8.1% vs 8.0%). Compared with the bare metal stent group, patients treated with drug-eluting stents had significantly lower rates of myocardial infarction (3.2% vs 6.0%; p <0.01), stroke (1.2% vs 2.7%; p <0.05), and target vessel revascularization (10.4% vs 14.9%; p <0.01) without any difference in the stent thrombosis rate (3.7% vs 4.3%; p = 0.57) or mortality rate (4.0% vs 5.2%; p = 0.21). In conclusion, the data generated from the German Drug-Eluting Stent registry revealed no differences between patients receiving a paclitaxel-eluting stent and sirolimus-eluting stent in a "real-world" setting with regard to the clinical outcomes at 1 year.