Experimental validation and clinical feasibility of 3D reconstruction of coronary artery bifurcation stents using intravascular ultrasound

The structural morphology of coronary stents and the local hemodynamic environment following stent deployment in coronary arteries are crucial determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to facilitate geometrically accurate three-dimensional (3D) reconstruction of coronary stents. This work presents an innovative algorithm for the 3D reconstruction of coronary artery stents, leveraging intravascular ultrasound (IVUS) and angiography. The accuracy and reproducibility of our method were tested in stented patient-specific silicone models, with micro-computed tomography serving as a reference standard. We also evaluated the clinical feasibility and ability to perform computational fluid dynamics (CFD) studies in a clinically stented coronary bifurcation. Our experimental and clinical studies demonstrated that our proposed algorithm could reproduce the complex 3D stent configuration with a high degree of precision and reproducibility. Moreover, the algorithm was proved clinically feasible in cases with stents deployed in a diseased coronary artery bifurcation, enabling CFD studies to assess the hemodynamic environment. In combination with patient-specific CFD studies, our method can be applied to stenting optimization, training in stenting techniques, and advancements in stent research and development.

Intravascular Imaging Findings After PCI in Patients With Focal and Diffuse Coronary Artery Disease

BACKGROUND

Following percutaneous coronary intervention (PCI), optical coherence tomography provides prognosis information. The pullback pressure gradient is a novel index that discriminates focal from diffuse coronary artery disease based on fractional flow reserve pullbacks. We sought to investigate the association between coronary artery disease patterns, defined by coronary physiology, and optical coherence tomography after stent implantation in stable patients undergoing PCI.

METHODS AND RESULTS

This multicenter, prospective, single-arm study was conducted in 5 countries (NCT03782688). Subjects underwent motorized fractional flow reserve pullbacks evaluation followed by optical coherence tomography-guided PCI. Post-PCI optical coherence tomography minimum stent area, stent expansion, and the presence of suboptimal findings such as incomplete stent apposition, stent edge dissection, and irregular tissue protrusion were compared between patients with focal versus diffuse disease. Overall, 102 patients (105 vessels) were included. Fractional flow reserve before PCI was 0.65±0.14, pullback pressure gradient was 0.66±0.14, and post-PCI fractional flow reserve was 0.88±0.06. The mean minimum stent area was 5.69±1.99 mm2 and was significantly larger in vessels with focal disease (6.18±2.12 mm2 versus 5.19±1.72 mm2, P=0.01). After PCI, incomplete stent apposition, stent edge dissection, and irregular tissue protrusion were observed in 27.6%, 10.5%, and 51.4% of the cases, respectively. Vessels with focal disease at baseline had a lower prevalence of incomplete stent apposition (11.3% versus 44.2%, P=0.002) and more irregular tissue protrusion (69.8% versus 32.7%, P<0.001).

CONCLUSIONS

Baseline coronary pathophysiological patterns are associated with suboptimal imaging findings after PCI. Patients with focal disease had larger minimum stent area and a higher incidence of tissue protrusion, whereas stent malapposition was more frequent in patients with diffuse disease.

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.

Impact of acute and persistent stent malapposition after percutaneous coronary intervention on adverse cardiovascular outcomes

INTRODUCTION

The association of coronary stent malapposition (SM) and adverse clinical outcomes after percutaneous coronary intervention (PCI) remains unclear. We aimed to perform a systematic review and meta-analysis of randomized and observational studies to assess the association between acute and persistent SM detected using intravascular ultrasound (IVUS) or optical coherence tomography (OCT) and adverse cardiovascular outcomes.

EVIDENCE ACQUISITION

Available studies were identified through a systematic search of PubMed, reference lists of relevant articles, and Medline. Main efficacy outcomes of interest were: device-oriented composite endpoint (DoCE, including cardiac death, myocardial infarction [MI], target lesion revascularization [TLR], and stent thrombosis [ST]), major safety events (MSE, including cardiac death, MI and ST), TLR, and ST. A sensitivity analysis regarding the impact of major malapposition was also performed.

EVIDENCE SYNTHESIS

A total of 9 studies enrolling 6497 patients were included in the meta-analysis. After a mean follow-up of 24±14 months, overall acute and/or persistent malapposition was not significantly associated with the occurrence of all the outcomes of interest, including DoCE (risk ratio [RR] 1.00, 95% confidence interval [CI, 0.79-1.26], P=0.99), MSE (RR 1.42, 95%CI [0.81-2.50], P=0.22), TLR (RR 0.84, 95%CI [0.59-1.19], P=0.33), and ST (RR 1.16, 95%CI [0.48-2.85], P=0.74). In the sensitivity analysis, we found a significant increase of MSE in patients with major malapposition (RR 2.97, 95%CI [1.51-5.87], P=0.001).

CONCLUSIONS

Acute and persistent SM were not overall associated with adverse cardiovascular clinical outcomes at follow-up. However, major malapposition was associated with an increased risk of major safety events, including cardiac death, MI and ST. These findings should be taken into account during stent implantation and PCI optimization.

Impact of Reference Mismatch on Procedure Outcomes of Percutaneous Coronary Intervention

A significant mismatch between proximal and distal reference lumen diameters of the target lesion may pose challenges during percutaneous coronary intervention (PCI) and therefore influence the outcomes. We investigated total 1706 lesions underwent IVUS guided percutaneous coronary intervention, that were divided into 2 groups, including 411 lesions in Mismatch group and 1295 lesions in Non-Mismatch group. After propensity score matching, 397 lesions in each group were selected for final data set. The analysis showed that Mismatch group PCI required more frequently use of post-stenting optimization (79.6% vs 53.9%, P < .001) using higher max pressure (19.5 ± 3.9 vs 16.7 ± 3.7 atm, P < .001). Besides, Mismatch group also encountered more PCI major complications (7.8% vs 4.0%, P = .024) and lower procedure success rate (91.4% vs 95.5%, P = .022). On final angiogram, Mismatch group had smaller minimum lumen diameter (2.62 ± .45 vs 2.90 ± .57 mm, P < .001) and lower angiographic success rate (93.2% vs 96.7%, P = .023). On final IVUS, Mismatch group had higher rate of incomplete stent apposition and stent edge dissection (6.3% vs 3.0%, P = .029 and 2.5% vs .5%, P = .021, respectively). In conclusion, reference mismatch posed significant challenging during PCI that led to unfavorable procedural outcomes. These impacts may translate into long-term clinical implications that need to be addressed in future studies.

In vivo detection of plaque erosion by intravascular optical coherence tomography using artificial intelligence

Plaque erosion is one of the most common underlying mechanisms for acute coronary syndrome (ACS). Optical coherence tomography (OCT) allows in vivo diagnosis of plaque erosion. However, challenge remains due to high inter- and intra-observer variability. We developed an artificial intelligence method based on deep learning for fully automated detection of plaque erosion in vivo, which achieved a recall of 0.800 ± 0.175, a precision of 0.734 ± 0.254, and an area under the precision-recall curve (AUC) of 0.707. Our proposed method is in good agreement with physicians, and can help improve the clinical diagnosis of plaque erosion and develop individualized treatment strategies for optimal management of ACS patients.

Three dimensional reconstruction of coronary artery stents from optical coherence tomography: experimental validation and clinical feasibility

The structural morphology of coronary stents (e.g. stent expansion, lumen scaffolding, strut apposition, tissue protrusion, side branch jailing, strut fracture), and the local hemodynamic environment after stent deployment are key determinants of procedural success and subsequent clinical outcomes. High-resolution intracoronary imaging has the potential to enable the geometrically accurate three-dimensional (3D) reconstruction of coronary stents. The aim of this work was to present a novel algorithm for 3D stent reconstruction of coronary artery stents based on optical coherence tomography (OCT) and angiography, and test experimentally its accuracy, reproducibility, clinical feasibility, and ability to perform computational fluid dynamics (CFD) studies. Our method has the following steps: 3D lumen reconstruction based on OCT and angiography, stent strut segmentation in OCT images, packaging, rotation and straightening of the segmented struts, planar unrolling of the segmented struts, planar stent wireframe reconstruction, rolling back of the planar stent wireframe to the 3D reconstructed lumen, and final stent volume reconstruction. We tested the accuracy and reproducibility of our method in stented patient-specific silicone models using micro-computed tomography (μCT) and stereoscopy as references. The clinical feasibility and CFD studies were performed in clinically stented coronary bifurcations. The experimental and clinical studies showed that our algorithm (1) can reproduce the complex spatial stent configuration with high precision and reproducibility, (2) is feasible in 3D reconstructing stents deployed in bifurcations, and (3) enables CFD studies to assess the local hemodynamic environment within the stent. Notably, the high accuracy of our algorithm was consistent across different stent designs and diameters. Our method coupled with patient-specific CFD studies can lay the ground for optimization of stenting procedures, patient-specific computational stenting simulations, and research and development of new stent scaffolds and stenting techniques.

Impact of stent malapposition on intracoronary flow dynamics: An optical coherence tomography-based patient-specific study

Percutaneous coronary intervention with stent implantation has emerged as a popular approach to treat coronary artery stenosis. Stent malapposition (SM), also referred as incomplete stent apposition, could reduce stent tissue coverage and hence increase the risk of late stent thrombosis. The objective of this study was to investigate the impact of SM on intracoronary flow dynamics by combining optical coherence tomography (OCT) image-based model reconstruction and computational analysis. Firstly, a stenosed coronary artery model was reconstructed from OCT and angiography imaging data of a patient. Two structural analyses were carried out to simulate two types of coronary artery stent implantations: a fully-apposed (FA) case and a SM case. Then, based on the two deformed coronary geometries, two computational fluid dynamics (CFD) analyses were performed to evaluate the differences of hemodynamic metrics between the FA and the SM cases, including wall shear stress (WSS), time-averaged WSS (TWSS), oscillatory shear index (OSI), WSS gradient (WSSG), time-averaged WSSG (TWSSG), and relative residence time (RRT). The results indicated that maximum flow velocity was higher in the SM case than that of the FA case, due to the incomplete expansion of the stent and artery. Moreover, the SM case had a lower percentage of areas of adverse WSS (< 0.5 Pa) and RRT (> 10/Pa) but a higher percentage of areas of adverse OSI (> 0.1) and WSSG (> 5000 Pa/m). Specifically, the differences of OSI, WSSG, and RRT between the two cases were relatively small. It was suggested that SM might not be responsible for negative hemodynamic metrics which would further result in stent thrombosis on the basis of the present specific model.

Double kissing inflation outside the stent secures the patency of small side branch without rewiring

BACKGROUND

The jailed balloon technique is widely used for coronary bifurcation lesions, but a residual risk of SB occlusion remains, necessitating SB rewiring and further interventions, including balloon inflation or stenting, which may result in failure and SB loss. This study introduced a novel modified technique of small side branch (SB) protection, namely, double kissing inflation outside the stent (DKo) technique, for coronary bifurcations without the need for SB rewiring.

METHODS

We performed the DKo technique in consecutive patients in our center from 1/2019 to 12/2019. The procedure was as follows. We inserted a guide wire into both branches followed by proper preparation. The SB balloon was simultaneously inflated with main vessel (MV) stenting. The SB balloon remained in situ until it was kissing inflated with postdilation of the bifurcation core, which is different from traditional strategies. The proximal optimization technique was performed with a short noncompliant balloon strictly not exceeding the bifurcation. Rates of SB loss and in-hospital outcomes were evaluated.

RESULTS

The technique was successfully performed in all 117 enrolled patients without any rewiring or SB loss. The mean lesion lengths of the MV and SB were 38.3 ± 19.9 mm and 11.7 ± 7.1 mm, respectively. On average, 1.5 ± 0.6 stents were used per patient, while the mean pressure of the SB balloon was 7.4 ± 3.1 atm. DKo achieved excellent procedural success in the proximal and distal MVs: increased minimal lumen diameter (0.64 ± 0.58 mm to 3.05 ± 0.38 mm, p < 0.001; 0.57 ± 0.63 mm to 2.67 ± 0.35 mm, p < 0.001) and low residual stenosis (11.4 ± 3.4%; 7.2 ± 4.6%). DKo secured the patency of the SB without any rewiring and improved the SB stenosis with minimal lumen diameter (0.59 ± 0.48 mm to 1.20 ± 0.42 mm, p < 0.001) and stenosis (71.9 ± 19.4% to 42.2 ± 14.0%, p < 0.001). No MACE was noted in the hospital.

CONCLUSIONS

DKo for bifurcation lesions was shown to be acceptable with high procedural success and excellent SB protection.

Impact of Malapposed and Overlapping Stents on Hemodynamics: A 2D Parametric Computational Fluid Dynamics Study

Despite significant progress, malapposed or overlapped stents are a complication that affects daily percutaneous coronary intervention (PCI) procedures. These malapposed stents affect blood flow and create a micro re-circulatory environment. These disturbances are often associated with a change in Wall Shear Stress (WSS), Time-averaged WSS (TAWSS), relative residence time (RRT) and oscillatory character of WSS and disrupt the delicate balance of vascular biology, providing a possible source of thrombosis and restenosis. In this study, 2D axisymmetric parametric computational fluid dynamics (CFD) simulations were performed to systematically analyze the hemodynamic effects of malapposition and stent overlap for two types of stents (drug-eluting stent and a bioresorbable stent). The results of the modeling are mainly analyzed using streamlines, TAWSS, oscillatory shear index (OSI) and RRT. The risks of restenosis and thrombus are evaluated according to commonly accepted thresholds for TAWSS and OSI. The small malapposition distances (MD) cause both low TAWSS and high OSI, which are potential adverse outcomes. The region of low OSI decrease with MD. Overlap configurations produce areas with low WSS and high OSI. The affected lengths are relatively insensitive to the overlap distance. The effects of strut size are even more sensitive and adverse for overlap configurations compared to a well-applied stent.

Differential Vascular Responses to New-Generation Drug-Eluting Stenting According to Clinical Presentation: Three-Month Optical Coherence Tomographic Study

We evaluated early vascular responses after new-generation drug-eluting stent (DES) implantation. From 2 randomized trials, we identified 471 patients (138 patients with acute myocardial infarction [AMI] vs 333 patients with stable angina or unstable angina [SA/UA]) treated by DESs who underwent serial optical coherence tomography (OCT) from postprocedure to 3 months. At 3-month follow-up OCT, malapposed strut percentage was higher in AMI than in SA/UA (5.3% vs 0.7%, P < .001); it was markedly increased from postprocedure in AMI (2.0%-5.3%, P < .001), whereas it decreased in SA/UA (1.7%-0.7%, P < .001). Patients with AMI showed a higher risk of persistent (59% vs 37%; P < .001) or late-acquired malapposition (15% vs 8%; P = .04). Uncovered strut percentage at 3 months was also higher in AMI than in SA/UA (13.1% vs 6.7%, P < .001). The AMI presentation was the significant risk factor for both significant stent malapposition (SM, ≥200 μm; odds ratio [OR] = 3.45, CI = 1.85-7.14, P < .001) and uncovered stent (% uncovered struts >6.0%; OR = 2.44, CI = 1.35-4.76, P = .004), together with malapposed distance and postprocedural thrombi. Further, AMI presentation was the predictor for the occurrence of early period late-acquired and persistent malapposition. Serial OCT comparison analyses showed that patients with AMI compared with patients with SA/UA showed more delayed strut coverage, more severe degree SM or uncovered stents, and higher incidences of early period persistent or late-acquired SM.

Long-term Clinical Outcomes of Drug-Eluting Stent Malapposition

Previous pathologic, intravascular imaging, and clinical studies have investigated the association between adverse cardiac events and stent malapposition, including acute stent malapposition (ASM, that is detected at index procedure) and late stent malapposition (LSM, that is detected during follow-up) that can be further classified into late-persistent stent malapposition (LPSM, ASM that remains at follow-up) or late-acquired stent malapposition (LASM, newly developed stent malapposition at follow-up that was not present immediately after index stent implantation). ASM has not been associated with adverse cardiac events compared with non-ASM, even in lesions with large-sized malapposition. The clinical outcomes of LSM may depend on its subtype. The recent intravascular ultrasound studies with long-term follow-up have consistently demonstrated that LASM steadily increased the risk of thrombotic events in patients with first-generation drug-eluting stents (DESs). This association has not yet been identified in LPSM. Accordingly, it is reasonable that approaches to stent malapposition should be based on its relationship with clinical outcomes. ASM may be tolerable after successful stent implantation, whereas prolonged anti-thrombotic medications and/or percutaneous interventions to modify LASM may be considered in selected patients with first-generation DESs. However, these treatments are still questionable due to lack of firm evidences.

Post-dilatation improves stent apposition in patients with ST-segment elevation myocardial infarction receiving primary percutaneous intervention: A multicenter, randomized controlled trial using optical coherence tomography

BACKGROUND

Stent failure is more likely in the lipid rich and thrombus laden culprit lesions underlying ST-segment elevation myocardial infarction (STEMI). This study assessed the effectiveness of post-dilatation in primary percutaneous coronary intervention (pPCI) for acute STEMI.

METHODS

The multi-center POST-STEMI trial enrolled 41 consecutive STEMI patients with symptom onset <12 hours undergoing manual thrombus aspiration and Promus Element stent implantation. Patients were randomly assigned to control group (n=20) or post-dilatation group (n=21) in which a non-compliant balloon was inflated to >16 atm pressure. Strut apposition and coverage were evaluated by optical coherence tomography (OCT) after intracoronary verapamil administration via thrombus aspiration catheter, post pPCI and at 7-month follow-up. The primary endpoint was rate of incomplete strut apposition (ISA) at 7 months after pPCI.

RESULTS

There were similar baseline characteristics except for stent length (21.9 [SD 6.5] mm vs. 26.0 [SD 5.8] mm, respectively, P=0.03). In post-dilatation vs. control group, ISA rate was lower (2.5% vs. 4.5%, P=0.04) immediately after pPCI without affecting final TIMI flow 3 rate (95.2% vs. 95.0%, P>0.05) or corrected TIMI frame counts (22.6±9.4 vs. 22.0±9.7, P>0.05); and at 7-month follow-up (0.7% vs. 1.8%, P<0.0001), the primary study endpoint, with similar strut coverage (98.5% vs. 98.4%, P=0.63) and 1-year rate of major adverse cardiovascular events (MACE).

CONCLUSION

In STEMI patients, post-dilatation after stent implantation and thrombus aspiration improved strut apposition up to 7 months without affecting coronary blood flow or 1-year MACE rate. Larger and longer term studies are warranted to further assess safety (ClinicalTrials.gov identifier: NCT02121223).

Ten-Year Clinical Outcomes of Late-Acquired Stent Malapposition After Coronary Stent Implantation

Objective:

The goal of this study was to determine the impact of late-acquired stent malapposition (LASM) on long-term clinical outcomes in patients treated with coronary stent implantation.

Approach and Results:

We investigated major adverse cardiac event during 10 years after 6-month intravascular ultrasound examination using our previous studies database. A total of 732 patients treated with bare-metal stent (54 LASM versus 678 non-LASM) and 529 patients treated with first-generation drug-eluting stent (82 LASM versus 447 non-LASM), who did not have clinical event or censoring at the time of follow-up intravascular ultrasound, were included for the present analysis. major adverse cardiac event was defined as the composite of cardiac death, target vessel–related myocardial infarction, target lesion revascularization and stent thrombosis. Multivariable adjustment and inverse probability weight were performed to consider baseline differences. After multivariable adjustment, LASM was related to a greater risk of major adverse cardiac event (hazard ratio, 1.666 [95% CI, 1.041–2.665]; P =0.0333) and very-late stent thrombosis (hazard ratio, 3.529 [95% CI, 1.153–10.798]; P =0.0271) than non-LASM in patients treated with first-generation drug-eluting stent, but not in those treated with bare-metal stent. Results were consistent after inverse probability weight. Among patients with LASM of first-generation drug-eluting stent, no late stent thrombosis occurred in patients who continued to receive dual antiplatelet therapy.

Conclusions:

The relationship between LASM and major adverse cardiac event might depend on the type of implanted stents during the long-term follow-up, highlighting the clinical significance of polymers and drugs in drug-eluting stent system.

Comparison of diagnostic performance in assessing the rewiring position into a jailed side branch between online 3D reconstruction systems version 1.1 and 1.2 derived from optical frequency domain imaging

The three-dimensional reconstruction of optical coherence tomography and optical frequency domain imaging (3D-OCT/OFDI) helps optimize bifurcation percutaneous coronary interventions (PCIs) with side branch (SB) dilatation by identifying the optimal rewiring position. 3D-OCT/OFDI’s diagnostic performance for assessing the rewiring position into a jailed SB is unknown. We retrospectively evaluated the diagnostic performances of a conventional (ver. 1.1) and a new (ver. 1.2) online 3D-OFDI reconstruction system based on an offline 3D reconstruction system’s performance. We analyzed 45 patients’ 52 OFDI pullbacks with main vessel stenting followed by rewiring into a jailed SB for coronary bifurcation lesions. We counted the undetected stent struts in the polygon of confluence as the stent detection performance. We assessed the diagnostic agreement regarding the rewiring position into a jailed SB by the three 3D reconstruction systems. The percentage of undetected struts and the diagnostic agreement of ver.1.2 were significantly better than those of ver.1.1 [5.1 ± 5.1% vs. 30.2 ± 14.2%; p < 0.0001, and 94.2% (49/52) vs. 76.9% (40/52); p = 0.0120]. The new online 3D-OFDI reconstruction system provides better diagnostic performance than the conventional online system for assessing the rewiring position into a jailed SB.

Vulnerable struts with CRE8, Biomatrix and Xience stents assessed with OCT and their correlation with clinical variables at 6-month follow-up: the CREBX-OCT study

First-generation drug eluting stents (DES) reduced the incidence of restenosis and need for repeated target lesion revascularization but, in autoptic studies, frequently resulted in incomplete endothelial coverage, which is an important predictor of late adverse events and increased mortality after stent implantation. More recently, not only uncovered, but also malapposed or protruding struts have been considered vulnerable structures, as they are deemed to perturb blood flow, whereas only struts well embedded into the vessel wall are considered stable. We compared the number of uncovered and of other vulnerable (protruding or malapposed) struts among three different second-generation drug-eluting stents (DES) (Cre8, Biomatrix, Xience), using optical coherence tomography (OCT) 6 months after implantation. Moreover, we analyzed the relationship between the percentage of vulnerable struts and the clinical characteristics of patients. 60 patients with stable angina or non-ST-Elevation acute coronary syndrome and indication to percutaneous angioplasty were randomly assigned to receive one of the three DES. After 6 months, OCT images were obtained. After 6 months, OCT images were obtained (1289 cross sections; 10,728 struts). None of the three DES showed non-coated struts or areas of stent thrombosis. Significant differences in the average number of protruding struts (Cre8: 33.9 ± 12.6; Biomatrix: 26.2 ± 18.1; Xience: 13.2 ± 8.5; p < 0.001) and in the proportion of malapposed struts (Cre8: 0.7%; Biomatrix: 0.9%; Xience: 0.0%; p = 0.040) and of incomplete stent apposition area (Cre8: 10.4%; Biomatrix: 4.7%; Xience: 0.7%; p < 0.001) were observed. No significant difference was found in neointimal hyperplasia area with a not significant tendency toward greater minimal and maximal struts thickness for Biomatrix. In comparison with Cre8 and Biomatrix, Xience showed a significantly lower proportion of vulnerable struts in all clinical sub-groups considered. In the group of 60 patients a significant relation was found between age and number of vulnerable struts (p = 0.014). The three second-generation DES were similarly effective in permitting neo-intimal formation and complete struts coating 6 months after implantation, but Cre8 and Biomatrix showed a greater proportion of protruding and malapposed struts.Trail Registry: Clinical Trials.gov Identifier: NCT02850497.

Safety and effectiveness of the self-aPposing, bAlloon-delivered, siRolimus-eluting stent for the Treatment of the coronary Artery disease: SPARTA, a multicenter experience

AIMS

To assess the long-term outcomes of patients treated with sirolimus-eluting Stentys stent in a real-life setting.

BACKGROUND

Few data regarding the safety and effectiveness of self-apposing sirolimus-eluting Stentys stent are available.

METHODS

278 patients (30% stable coronary artery disease, 70% acute coronary syndromes, and 54% on unprotected left main) treated with sirolimus eluting Stentys stent were retrospectively included in the self-aPposing, bAlloon-delivered, siRolimus-eluting stent for the Treatment of the coronary Artery disease multicenter registry. Major adverse cardiovascular events (MACE, a composite of cardiac death, myocardial infarction, target lesion revascularization, stent thrombosis) were the primary end-point, single components of MACE were the secondary ones.

RESULTS

After 13 months (interquartile range 5-32), MACE was 14%. Stent thrombosis occurred in 3.9% of the patients (2.5% definite stent thrombosis and 1.4% probable stent thrombosis), 66% of them presenting with ST-segment elevation myocardial infarction (STEMI) at admission. Cardiovascular death, target lesion revascularization and myocardial infarction was 4.7%, 8.3%, and 7.2%, respectively. At multivariate analysis, risk of MACE was increased by diabetes (hazard ratios 4.76; P = 0.002) but was not affected by the indication leading to sirolimus-eluting Stentys stent implantation (marked vessel tapering vs. coronary ecstasies, hazard ratios 0.74, P = 0.71).

CONCLUSION

Sirolimus-eluting Stentys stent may represent a potential solution for specific coronary anatomies such as bifurcation, ectasic, or tapered vessels. Risk of stent thrombosis appears related to clinical presentation with STEMI and to anatomic features, stressing the importance of the use of intracoronary imaging for self-expandable stents implantation.

Severe Acute Stent Malapposition After Drug-Eluting Stent Implantation: Effects on Long-Term Clinical Outcomes

Background

The effects of severe acute stent malapposition (ASM) after drug‐eluting stent implantation on long‐term clinical outcomes are not clearly understood. We evaluated long‐term clinical outcomes of severe ASM using optical coherence tomography.

Methods and Results

We pooled patient‐ and lesion‐level data from 6 randomized studies. Five studies investigated follow‐up drug‐eluting stent strut coverage and one investigated ASM. In this data set, a total of 436 patients with 444 lesions underwent postintervention optical coherence tomography examination and these data were included in the analysis. Severe ASM was defined as lesions with ≥400 μm of maximum malapposed distance or ≥1 mm of maximum malapposed length. Composite events (cardiac death, target lesion–related myocardial infarction, target lesion revascularization, and stent thrombosis) were compared between patients with and without severe ASM. The postintervention optical coherence tomography findings indicated that 62 (14.2%) patients had lesions with ≥400 μm of maximum malapposed distance and 186 (42.7%) patients had lesions with ≥1 mm of maximum malapposed length. The 5‐year clinical follow‐up was completed in 371 (86.1%) of the eligible 431 patients. The cumulative rate of composite events was similar among the patients in each group during 5‐year follow‐up: 3.3% in patients with ASM ≥400 μm of maximum malapposed distance versus 3.1% in those with no ASM or ASM <400 μm of maximum malapposed distance (P=0.89), and 1.2% in patients with ASM ≥1 mm of maximum malapposed length versus 4.6% in those with no ASM or ASM <1 mm of maximum malapposed length (P=0.06).

Conclusions

During the 5‐year follow‐up, ASM severity was not associated with long‐term clinical outcomes in patients treated with drug‐eluting stents.

Long-Term Clinical Outcomes of Late Stent Malapposition Detected by Optical Coherence Tomography After Drug-Eluting Stent Implantation

Background

The relationship between late stent malapposition (LSM) and adverse cardiovascular events is controversial. Studies are needed to evaluate long‐term (>5 years) clinical outcomes of LSM detected by optical coherence tomography (OCT) after drug‐eluting stent implantation.

Methods and Results

We investigated long‐term clinical outcomes of OCT‐detected LSM in 351 patients who received drug‐eluting stents and were examined by both poststent and follow‐up OCT (175±60 days after drug‐eluting stent implantation) from January 2009 to December 2011. LSM was observed in 99 patients (28%). We evaluated the cumulative rate of composite events (cardiovascular death, target‐vessel–related myocardial infarction, target‐vessel revascularization, and stent thrombosis). During 80.1±24.5 months of follow‐up, very late stent thrombosis did not occur in any patients with LSM. The cumulative 8‐year rate of composite events was 7.3% in patients with LSM and 10.5% in patients without LSM (P=0.822, log‐rank test). We further divided patients into the following 4 groups: patients with both late‐persistent and late‐acquired stent malapposition (n=23), patients with late‐persistent stent malapposition alone (n=45), patients with late‐acquired stent malapposition alone (n=31), and patients without LSM (n=252). The cumulative 8‐year rates of composite events were similar among these 4 groups (0%, 9.6%, 9.7%, and 10.5%, respectively; P=0.468 by log‐rank test).

Conclusions

During long‐term follow‐up (>5 years), very late stent thrombosis did not occur in patients with OCT‐detected LSM. The rates of adverse clinical events were similar between patients with LSM versus those without LSM. Presence of OCT‐detected LSM was not associated with unfavorable clinical outcomes.

See Editorial by Ali et al

The "Oculo-Appositional Reflex": Should Optical Coherence Tomography-Detected Stent Malapposition Be Corrected?

See Article by Im et al

Numerical study of incomplete stent apposition caused by deploying undersized stent in arteries with elliptical cross-sections

Incomplete stent apposition (ISA) is one of the causes leading to post-stent complications, which can be found when an undersized or under-expanded stent is deployed at lesions. Previous research efforts have focused on ISA in idealized coronary arterial geometry with circular cross-sections. However, arterial cross-section eccentricity plays an important role in both location and severity of ISA. Computational fluid dynamics (CFD) simulations are carried out to systematically study the effects of ISA in arteries with elliptical cross-sections, as such stents are partially embedded on the minor axis sides of the ellipse and malapposed elsewhere. Overall, ISA leads to high time-averaged WSS (TAWSS) at the proximal end of the stent and low TAWSS at the ISA transition region and the distal end. Shear rate depends on both malapposition distance and blood stream locations, which is found to be significantly higher at the inner stent surface than the outer surface. The proximal high shear rate signifies increasing possibility in platelet activation, when coupled with low TAWSS at the transition and distal region which may indicate a nidus for in-stent thrombosis.

Innovative invasive management without stent implantation guided by optical coherence tomography in acute coronary syndrome

BACKGROUND

A two-step strategy of invasive management without stenting, guided by optical coherence tomography (OCT), in selected patients with acute coronary syndrome (ACS), might avoid systematic stent implantation and allow medical therapy alone.

AIMS

To assess the feasibility and safety of such a procedure, and to define coronary imaging characteristics in a specific population.

METHODS

This single-centre proof-of-concept study included all patients with ACS who benefited from a two-step revascularization procedure with optimal reperfusion during primary percutaneous coronary intervention followed by delayed angiography and OCT. OCT imaging determined medical therapy treatment alone without stenting in case of absence of vulnerable plaque rupture and <70% stenosis. Follow-up consisted of screening for major adverse cardiac events (MACE) at 12months.

RESULTS

Forty-six patients were included, mainly men (86.9%) and smokers (65.2%), with a mean age of 47.1years. Most cases (80.4%) were large thrombus burden lesions. Delayed angiography and OCT were performed in a median period of 6 [3-10] days. No adverse events occurred between the initial and second angiograms. Plaque rupture was detected in 39.1% of patients, plaque erosion in 54.3% and calcified nodule in 6.5%. Twenty-three patients benefited from systematic delayed OCT over a median period of 171days, showing an increase in minimal lumen area. At 12months, two patients (4.3%) presented MACE and were stented. No sudden death or myocardial infarction recurrence occurred.

CONCLUSIONS

Analysing ACS mechanisms by OCT might facilitate treatment decisions in patients with ST-segment elevation myocardial infarction managed by a two-step procedure. Conservative treatment with antithrombotic therapy without stenting seems to be a reliable option in a selected population.

Five-year clinical follow-up of the STENTYS self-apposing stent in complex coronary anatomy: a single-centre experience with report of specific angiographic indications

Objectives

We sought to investigate angiographic indications for the use of the STENTYS technique and evaluated the long-term safety and clinical efficacy of the stent.

Background

Coronary lesions involving complex anatomy, including aneurysmatic, ectatic, or tapered vessel segments often carry a substantial risk of stent malapposition. The self-apposing stent technique may reduce the risk of stent malapposition and therefore improve clinical outcomes.

Methods

A total of 120 consecutive patients treated with the STENTYS stent were included (drug-eluting stent (DES) n = 101, bare-metal stent (BMS) n = 19). All lesions were scored for angiographic indications for the STENTYS stent, including aneurysms, ectasias, tapering, absolute diameters, bifurcation lesions, and saphenous vein grafts. Off-line quantitative coronary angiography analyses were performed pre-procedure and post-procedure. Five years follow-up was obtained including cardiac death, target vessel myocardial infarction (TV-MI), target vessel revascularisation, stent thrombosis, and the composite endpoint target vessel failure (cardiac death, TV-MI and target vessel revascularisation).

Results

Angiographic indications for STENTYS use were aneurysm (30%), ectasia (19%), tapering (27%), bifurcation lesions (8%), and saphenous vein graft lesions (16%) and absolute diameters (22%). Mean maximal diameter was 4.51 ± 0.99 mm. At 5‑year follow-up target vessel failure rates were 24.1% in the total cohort (DES 22.8% vs. BMS 33%, p = 0.26). Definite stent thrombosis rate was 3.8% at 5‑year follow-up in this cohort with complex and high-risk lesions (DES 4.5% vs. BMS 0%, p = 0.39).

Conclusions

Angiographic indications for the use of the self-apposing stent were complex lesions with atypical coronary anatomy. Our data showed reasonable stent thrombosis rates at 5‑year follow-up, considering the high-risk lesion characteristics.

Electronic supplementary material

The online version of this article (10.1007/s12471-018-1111-7) contains supplementary material, which is available to authorized users.

Multianalysis with optical coherence tomography and vasomotion in everolimus-eluting stents and everolimus-eluting biovascular scaffolds: the MOVES trial

Aims

To compare endothelium-dependent vasomotor function and vascular healing 15 months after implantation of two new-generation drug-eluting stents and biovascular scaffolds (BVS).

Methods and results

A total of 28 patients previously treated with a SYNERGY stent (bioabsorbable polymer everolimus-eluting stents (BP-EES)), a PROMUS stent (persistent polymer everolimus-eluting stents (PP-EES)) or an ABSORB (BVS) underwent control coronary angiography, 15 months after implantation, coupled with optical coherence tomography imaging and supine bicycle exercise. Intracoronary nitroglycerin was administered after exercise testing. Coronary vasomotor response was assessed using quantitative coronary angiography at rest, during supine bicycle exercise and after nitroglycerin. The primary end point was the percent change in mean lumen diameter compared with baseline. Secondary end points were strut coverage and apposition.There were no significant differences in vasomotor response between the three treatment groups. Patients with PP-EES showed significant vasoconstriction of the proximal peristent segment at maximum exercise (P=0.02). BP-EES (2.7%, 95% CI 0 to 5.5) and BVS (3.2%, 95% CI 0 to 6.7) showed less uncovered struts than PP-EES (12.1%, 95% CI 2.9 to 21.3, P=0.02 and 0.09, respectively). Complete strut apposition was more frequently seen with BP-EES (99.6%, 95% CI 99.2 to 100) than with BVS (98.9%, 95% CI 98.2 to 99.6, P=0.04) or PP-EES (95.0%, 95% CI 91.6 to 98.5, P=0.001).

Conclusion

BVS and thin strut BP-EES have a reassuring vasomotion profile, suggesting minimal endothelial dysfunction 15 months after implantation.

Methods to assess bioresorbable vascular scaffold devices behaviour after implantation

Bioresorbable vascular scaffolds (BRS) represent a novel approach for coronary revascularization offering several advantages as compared to current generation DES, potentially reducing rate of late adverse events and avoiding permanent vessel caging. Nevertheless, safety concerns have been raised for an increased risk of scaffold thrombosis (ScT) in both early and late phases, probably related to a suboptimal scaffold implantation. In this context, the use of different imaging methodologies has been strongly suggested in order to guarantee an optimal implantation. We herein analyze the different imaging methodologies available to assess BRS after implantation and at follow-up.

Occlusion Status on Magnetic Resonance Angiography Is Associated with Risk of Delayed Ischemic Events in Cerebral Aneurysms Treated with Stent-Assisted Coiling

OBJECTIVE

Management after stent-assisted coiling (SAC) for unruptured intracranial aneurysm is sometimes difficult because close monitoring for ischemic events for a long period of time after the procedure is necessary. The purpose of this study was to clarify the usefulness of magnetic resonance angiography (MRA) at follow-up after SAC.

METHODS

Sixty-six consecutive cases of SAC for unruptured intracranial aneurysm in our institute and affiliated hospitals were retrospectively reviewed for a delayed ischemic event. Occlusion status of the aneurysm and stent apposition on time-of-flight (TOF)-MRA, patient demographics, and characteristics of the aneurysms were analyzed for a possible relationship to delayed ischemic events.

RESULTS

Over a median follow-up of 755 days, 14 patients had delayed ischemic events after a median follow-up of 230.5 days. All of the ischemic events were transient or asymptomatic. Univariate analysis revealed that the history of hypertension (P = 0.042) and the occlusion status of the aneurysm (P = 0.006) were significantly associated with delayed ischemic events. Multivariate analysis indicated that dome filling had a hazard ratio of 4.96 (95% confidence interval [CI], 1.30-23.60) and 3.74 (95% CI, 1.10-13.34), compared with neck remnant and complete obliteration, respectively. Six of 7 patients who had persistent dome filling during follow-up developed a delayed ischemic event.

CONCLUSIONS

In this preliminary study, dome filling on follow-up TOF-MRA is a possible risk factor for delayed ischemic events. TOF-MRA could be a modality for tailored management after SAC.

Classification of mechanisms of strut malapposition after angiographically optimized stent implantation: An optical coherence tomography study

AIMS

To elucidate causes and extent of strut malapposition in angiographically optimized stenting.

METHODS AND RESULTS

Using a new classification system for strut malapposition, the mechanisms of stent strut malapposition were classified as localized lumen enlargement, vessel asymmetry, stent undersizing, strut underexpansion and stent deployment issue. Stent implantations (n = 110) in 100 consecutive patients undergoing optical coherence tomography (OCT) after the operator considered the stent as optimally deployed angiographically were reviewed to determine if strut apposition was complete. 127,894 stent struts in 110 stents were analyzed. There were 6,644 struts malapposed (5.2% ±7.3%), with strut malapposition found in 82 of 110 stents (74.5%). Localized lumen enlargement was the most common cause of malapposition (74.4% of malapposition clusters). Stent undersizing was the second most common cause (46.3%) followed by strut under-expansion in 29.3%, stent deployment issue in 18.2%, and vessel asymmetry in 9.7%.

CONCLUSION

Malapposition of any degree is common after angiographic stent optimization, occurring in up to three-quarters of stents. The most frequent mechanism was localized lumen enlargement. The second most common cause of strut malapposition was stent undersizing, which was angiographically invisible. Whether performing OCT after angiographic optimization improves short- and long-term outcomes requires further study. © 2017 Wiley Periodicals, Inc.

Primary angioplasty: Effect of deferred stenting on stent size

BACKGROUND

Primary angioplasty with immediate stenting (IS) is the gold standard for ST-segment elevation myocardial infarction (STEMI). Deferred stenting (DS) has been proposed to limit periprocedural complications, and may influence stent size because of thrombus and spasm alleviation.

AIM

We sought to study the effect of DS on stent size.

METHODS

Over the study period, 258 patients underwent primary angioplasty for STEMI (DS, n=84; IS, n=174). An informative coronary angiogram run - i.e. allowing for proper lesion analysis - was selected and anonymized by an independent operator. Two experienced operators randomly analysed these runs, and proposed stent dimensions after having measured vessel diameter and lesion length by quantitative coronary analysis. The primary objective was the variation in stent size between the two coronary angiograms.

RESULTS

The median delay between the two coronary angiograms was 2 days. Overall, the stent length was shorter (-1.64mm; P=0.030) and its diameter was larger (+0.13mm; P<0.001) during the second coronary angiogram, especially in the right coronary arteries.

CONCLUSIONS

DS led to the implantation of a larger and shorter stent; this is probably because DS allows for more accurate assessment of the residual lesion after relief of spasm and thrombus, and may have clinical consequences in terms of stent thrombosis and restenosis.

Late-acquired incomplete stent apposition after everolimus-eluting stent versus sirolimus-eluting stent implantation in patients with non-ST-segment elevation myocardial infarction and ST-segment elevation myocardial infarction

AIMS

Our aim was to evaluate the incidence and clinical outcomes of late-acquired incomplete stent apposition (LAISA) after implantation of first- and second-generation drug-eluting stents in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

Late-Acquired incomplete stent aPPOsition after everolimus-eluting stent versus sirolimus-eluting Stent ImplanTatION in pAtients with non ST-segment elevation Myocardial Infarction and ST-segment elevation myocardial infarction (APPOSITION-AMI) was a prospective, randomised study comparing LAISA after everolimus-eluting stent (EES) and sirolimus-eluting stent (SES) implantation in AMI patients. Intravascular ultrasound examination was serially performed post-procedurally and at eight-month follow-up in 195 AMI patients (205 native coronary lesions: 100 EES; 105 SES). LAISA was observed in 6.0% and 16.2% of EES- vs. SES-treated lesions (p=0.021), respectively. In 64.7% of SES-treated lesions, LAISA was caused by positive remodelling, whereas thrombus dissolution or plaque reduction was observed in 66.7% of EES-treated lesions. Among patients with LAISA, MACE developed in one (4.5%) in the SES group with no ST in either group up to one year.

CONCLUSIONS

The incidence of LAISA was lower in AMI patients treated with EES as compared to SES, mainly secondary to positive remodelling in SES- but not EES-treated lesions. Patients with LAISA in both groups showed a very low MACE incidence at one-year follow-up.

Optical coherence tomography to evaluate coronary stent implantation and complications

Coronary optical coherence tomography (OCT) is now an established imaging technique in many catheterization laboratories worldwide. With its near-histological view of the vessel wall and lumen interface, it offers unprecedented imaging quality to improve our understanding of the pathophysiology of atherosclerosis, plaque vulnerability, and vascular biology. Not only is OCT used to accurately detect atherosclerotic plaque and optimize stent position, but it can further characterize plaque composition, quantify stent apposition, and assess stent tissue coverage. Given that its resolution of 15 μm is well above that of angiography and intravascular ultrasound, OCT has become the invasive imaging method of choice to examine the interaction between stents and the vessel wall. This review focuses on the application of OCT to examine coronary stents, the mechanisms of stent complications, and future directions of OCT-guided intervention.

Reduction in incomplete stent apposition area caused by jailed struts after single stenting at left main bifurcation lesions: micro-CT analysis using a three-dimensional elastic bifurcated coronary artery model

Stent struts protruding into ostial side branch called “jailed strut” at bifurcation lesions is a likely cause of thrombus formation. We aimed to investigate the influences of multiple kissing balloon inflation (KBI) for stent expansion, and stent platform design, respectively, on the reduction of incomplete stent apposition area (ISA area) caused by jailed struts at a side-branch ostium, using a three-dimensional elastic left main (LM) bifurcated coronary artery model. The referenced LM bifurcation angle data of 209 patients were stratified by tertiles focusing on the angle between the LM trunk (LMT) and left anterior descending artery (LAD). A bifurcation model was fabricated with angles of 129°, 122.2°, and 76.4° for LMT–LAD, LMT–left circumflex (LCx), and LAD–LCx, respectively, and with diameters of 5, 3.75, and 3.5 mm for LMT, LAD, and LCx, respectively; these diameters fulfill Murray’s law. A 75 % stenosis was included along the LMT. One-time and three-time KBIs were conducted using two-link Nobori and three-link Xience Xpedition (n = 6 each). The ISA area was quantified using micro-CT. Three-time KBI was effective in reducing the ISA area compared with one-time KBI for both the Nobori (p = 0.05) and Xience Xpedition (p = 0.07). The ISA area was smaller in the Nobori than in the Xience Xpedition, both in one-time and three-time KBI (one-time KBI: p = 0.003; three-time KBI: p = 0.001). Our findings of this study on reducing the ISA area by focusing on an interventional technique and stent design may help to improve coronary bifurcation intervention for a possibly better long-term clinical outcome.

Angiographic and optical coherence tomography insights into bioresorbable scaffold thrombosis: single-center experience

BACKGROUND

As bioresorbable vascular scaffolds (BVSs) are being increasingly used in complex real-world lesions and populations, BVS thrombosis cases have been reported. We present angiographic and optical coherence tomography (OCT) findings in a series of patients treated in our center for definite bioresorbable scaffold thrombosis.

METHODS AND RESULTS

Up to June 2014, 14 patients presented with definite BVS thrombosis in our center. OCT was performed in 9 patients at the operator's discretion. Angiographic and OCT findings were compared with a control group comprising 15 patients with definite metallic stent thrombosis. In the BVS group, time interval from index procedure to scaffold thrombosis ranged from 0 to 675 days. Incomplete lesion coverage by angiography was identified in 4 of 14 cases, malapposition by OCT in 5 of 9 cases, strut discontinuity in 2 of 9 cases, and underexpansion in 2 of 9 cases. Five patients had discontinued dual antiplatelet therapy, and in 3 of them discontinued dual antiplatelet therapy discontinuation had occurred the week preceding the event. There were no significant differences in angiographic or OCT findings between BVS and metallic stent thrombosis.

CONCLUSIONS

Suboptimal implantation with incomplete lesion coverage, underexpansion, and malapposition comprises the main pathomechanism for both early and late BVS thrombosis, similar to metallic stent thrombosis. Dual antiplatelet therapy discontinuation seems to also be a secondary contributor in several late events. Our observations suggest that several potential triggers for BVS thrombosis could be avoided.

Computational simulation of platelet interactions in the initiation of stent thrombosis due to stent malapposition

Coronary stenting is one of the most commonly used approaches to open coronary arteries blocked due to atherosclerosis. Stent malapposition can induce thrombosis but the microscopic process is poorly understood. The objective of this study was to determine the platelet-level process by which different extents of stent malapposition affect the initiation of stent thrombosis. We utilized a discrete element model to computationally simulate the transport, adhesion, and activation of thousands of individual platelets and red blood cells during thrombus initiation in stented coronary arteries. Simulated arteries contained a malapposed stent with a specified gap distance (0, 10, 25, 50, or 200 μm) between the struts and endothelium. Platelet-level details of thrombus formation near the proximal-most strut were measured during the simulations. The relationship between gap distance and amount of thrombus in the artery varied depending on different conditions (e.g., amount of dysfunctional endothelium, shear-induced activation of platelets, and thrombogenicity of the strut). Without considering shear-induced platelet activation, the largest gap distance (200 μm) produced no recirculation and less thrombus than the smallest two gap distances (0 and 10 μm) that created recirculation downstream of the strut. However, with the occurrence of shear-induced platelet activation, the largest gap distance produced more thrombus than the two smallest gap distances, but less thrombus than an intermediate gap distance (25 μm). A large gap distance was not necessarily the most thrombogenic, in contrast to implications of some computational fluid dynamics studies. The severity of stent malapposition affected initial stent thrombosis differently depending on various factors related to fluid recirculation, platelet trajectories, shear stress, and endothelial condition.