Stent Expansion Research Articles

Abstract 18968: Safety and Efficacy of Shockwave Intravascular Lithotripsy in the Management of Calcified Coronary Arteries: A Systematic Review and Meta-Analysis

Introduction: Shockwave intravascular lithotripsy (SWL) aims to facilitate optimal stent delivery and expansion for improved blood flow in treating calcified coronary artery disease. We sought to assess the safety and efficacy of SWL in managing de novo calcified lesions, lesions after failed/sub-optimal pre-dilatation with conventional balloon-based devices, under-expanded stents, and in-stent restenosis. Methods: A comprehensive literature search (Medline, Embase, Web of Science, Cochrane, and Google Scholar) was performed for studies that evaluated SWL in managing calcified coronary lesions. Efficacy outcomes included residual stenosis <30% and successful stent delivery with a low incidence of device delivery failure. Safety outcomes included procedural complications and major adverse cardiovascular events (MACE). MACE is a composite outcome of all-cause mortality, cardiac mortality, myocardial infarction, target vessel/lesion revascularization, and stent thrombosis. Event rates across the included studies were pooled in a meta-analysis using the random effects model. An overall estimate and 95% confidence interval were reported for each outcome. Heterogeneity was estimated using the I-squared statistic. Results: Out of the 1446 identified studies, 40 were included, with a total of 2718 patients. Residual stenosis <30% was achieved in 91.3% of patients (95% confidence interval 89.7% to 92.6%). Device delivery failure occurred in 6.7% of patients (95% CI 5% to 9%). In-hospital MACE occurred in 6.1% of patients (95% CI 5% to 7.4%), 30-day MACE in 7.4% (95% CI 6.2% to 8.8%), 6-month MACE in 8.3% (95% CI 7.1% to 9.6%), and 1-year MACE in 10% (95% CI 8.7% to 11.4%). Conclusions: SWL is a safe and efficient calcium modification intervention with high clinical success, minimal angiographic complications, and a low adverse event rate. Direct comparisons with the standard of care are needed in larger studies to establish clinical utility and superiority.

Results of systematic patient outcome monitoring: Does post-dilatation during angiography-guided percutaneous coronary intervention improve clinical outcomes?

ObjectivesThis study evaluates clinical outcomes after implementing a liberal post-dilatation strategy during PCI. BackgroundPost-dilatation after percutaneous coronary intervention (PCI) is performed to achieve optimal stent expansion and reduce complications. However, its prognostic effects are unclear and conflicting. MethodsThis study is a pre-post-intervention analysis of two cohorts, before (2015-2017) and after (2018-2020) implementation of a liberal post-dilatation strategy. The primary end point consisted of major adverse cardiovascular events (MACE) at 30 days. Secondary end points consisted of the individual components of the primary end point as well as 1 year mortality and target vessel revascularization. ResultsA total of 10,153 patients were included: 5,383 in the pre-cohort and 4,770 in the post-cohort. The 30-day MACE was 5.00% in the pre-cohort and 4.09% in the post-cohort (p = 0.008; OR 0.75 (CI 0.61-0.93)). There was a significant difference between the pre- and post-cohort in 30-day mortality, respectively, 2.91% and 2.25% (p = .01; OR 0.70 (CI 0.53-0.93)), and MI at 30 days, 1.17% versus 0.59% (p = .003; OR 0.49 (CI 0.31-0.78)). At 1 year, there was a significant difference in mortality between the pre-cohort, 5.84%, and post-cohort, 5.19% (p = .02; OR 0.79 (CI 0.66-0.96)). ConclusionsA liberal post-dilatation strategy after PCI was associated with a significant decrease in 30-day MACE, 30-day MI, 30-day mortality, and 1-year mortality. Future studies are warranted to validate the causality between post-dilatation and improvement of clinical outcomes.

Prediction of stent under-expansion in calcified coronary arteries using machine learning on intravascular optical coherence tomography images

It can be difficult/impossible to fully expand a coronary artery stent in a heavily calcified coronary artery lesion. Under-expanded stents are linked to later complications. Here we used machine/deep learning to analyze calcifications in pre-stent intravascular optical coherence tomography (IVOCT) images and predicted the success of vessel expansion. Pre- and post-stent IVOCT image data were obtained from 110 coronary lesions. Lumen and calcifications in pre-stent images were segmented using deep learning, and lesion features were extracted. We analyzed stent expansion along the lesion, enabling frame, segmental, and whole-lesion analyses. We trained regression models to predict the post-stent lumen area and then computed the stent expansion index (SEI). Best performance (root-mean-square-error = 0.04 ± 0.02 mm2, r = 0.94 ± 0.04, p < 0.0001) was achieved when we used features from both lumen and calcification to train a Gaussian regression model for segmental analysis of 31 frames in length. Stents with minimum SEI > 80% were classified as “well-expanded;” others were “under-expanded.” Under-expansion classification results (e.g., AUC = 0.85 ± 0.02) were significantly improved over a previous, simple calculation, as well as other machine learning solutions. Promising results suggest that such methods can identify lesions at risk of under-expansion that would be candidates for intervention lesion preparation (e.g., atherectomy).

Value of stent boost imaging in decision making after coronary stenting

Background: Several studies reported the comparability of digital stent enhancement techniques (including stent boost imaging) in detecting suboptimal results of coronary stenting with Intra Vascular Ultrasound and optical coherence tomography. Aims: to assess results of stent deployment and determine the incidence of suboptimal results requiring changing final decision using stent boost imaging. Methods: This cross-sectional study included 120 patients eligible for PCI were recruited during a period of one year (January 2021 to 2022) using DES. Results: Suboptimal results were found in 38% of the PCI cases with stents (angiography guided). Importantly it was found that improper lesion preparation in our practice could not help improving stent optimization. Also, angiography guided PCI has significant incidence of suboptimal results. Digital stent enhancement techniques like stent boost have significant and important value in better decision making. After adjusting for age and sex, six factors were identified as independent predictors for final decision change (stent length, LAD/RCA affection, proximal segment affection, calcification, and optical coherence tomography. Conclusion: This study has confirmed the utility of stent boost for the optimization of PCI in daily practice. Stent Boost is a simple and costless technique that provides an accurate assessment of a deployed stent without extending the procedure time and without more risk. It appears to be useful for the immediate evaluation of stent expansion and optimization of PCI by additional post-dilatation, when appropriate. Future studies are needed to determine whether Stent Boost data will correlate with adverse long-term clinical outcomes in patients undergoing PCI.

Mitigating the risk of flow deterioration by deferring stent optimization in STEMI patients with large thrombus burden: Insights from a prospective cohort study

ObjectivesIt is uncertain, if omitting post-dilatation and stent oversizing (stent optimization) is safe and may decrease the risk for distal thrombus embolization (DTE) in STEMI patients with large thrombus burden (LTB).BackgroundIn patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI) with stenting, (DTE) and flow deterioration are common and increase infarct size leading to worse outcomes.MethodsFrom a prospective registry, 74 consecutive STEMI patients with LTB undergoing pPCI with stenting and intentionally deferred stent optimization were analyzed. Imaging data and outcomes up to 2 years follow-up were analyzed.ResultsOverall, 74 patients (18% females) underwent deferred stent optimization. Direct stenting was performed in 13 (18%) patients. No major complications occurred during pPCI. Staged stent optimization was performed after a median of 4 (interquartile range (IQR) 3; 7) days. On optical coherence tomography, under-expansion and residual thrombus were present in 59 (80%) and 27 (36%) cases, respectively. During deferred stent optimization, we encountered no case of flow deterioration (slow or no-reflow) or side branch occlusion. Minimal lumen area (mm2) and stent expansion (%) were corrected from 4.87±1.86mm to 6.82±2.36mm (p<0.05) and from 69±18% to 91±12% (p<0.001), respectively. During follow-up, 1 patient (1.4%) required target lesion revascularization and 1 (1.4%) patient succumbed from cardiovascular death.ConclusionsAmong STEMI patients with LTB, deferring stent optimization in the setting of pPCI appears safe and potentially mitigates the risk of DTE. The impact of this approach on infarct size and clinical outcomes warrants further investigation in a dedicated trial.

Load-sharing characteristics of stenting and post-dilation in heavily calcified coronary artery

In this work, stenting in non-calcified and heavily calcified coronary arteries was quantified in terms of diameter-pressure relationships and load transfer from the balloon to the artery. The efficacy of post-dilation in non-calcified and heavily calcified coronary arteries was also characterized in terms of load sharing and the changes in tissue mechanics. Our results have shown that stent expansion exhibits a cylindrical shape in non-calcified lesions, while it exhibits a dog bone shape in heavily calcified lesions. Load-sharing analysis has shown that only a small portion of the pressure load (1.4 N, 0.8% of total pressure load) was transferred to the non-calcified lesion, while a large amount of the pressure load (19 N, 12%) was transferred to the heavily calcified lesion. In addition, the increasing inflation pressure (from 10 to 20 atm) can effectively increase the minimal lumen diameter (from 1.48 to 2.82 mm) of the heavily calcified lesion, the stress (from 1.5 to 8.4 MPa) and the strain energy in the calcification (1.77 mJ to 26.5 mJ), which are associated with the potential of calcification fracture. Results indicated that increasing inflation pressure can be an effective way to improve the stent expansion if a dog bone shape of the stenting profile is observed. Considering the risk of a balloon burst, our results support the design and application of the high-pressure balloon for post-dilation. This work also sheds some light on the stent design and choice of stent materials for improving the stent expansion at the dog bone region and mitigating stresses on arterial tissues.

Conceptual design and analysis of novel hybrid auxetic stents with superior expansion

This paper presents a conceptual design and finite element (FE) simulation of a novel class of negative Poisson's ratio (NPR) stents with hybrid auxetic structures fabricated by FDM 3D printing technology. The desired structures were first designed in a planar form by a combination of re-entrant, star-shaped, and chiral unit-cells (UCs) but with a difference in the way of connecting UCs to each other. A planar form of the designed stent was 3D printed with thermoplastic polyurethane (TPU) filaments. Then, its mechanical behaviors under quasi-static tensile loading was analysed by the FE method and experimental testing. A good agreement was observed between the FE method and the experiment, and achievement of a significant NPR of −2.3 was revealed. By converting the planar structure into the shape of a stent, the stent expansion and its function were further investigated using the developed FE method based on a complete model consisting of a balloon, plaque, artery, and blood pressure. The results showed that the designed stent has a diameter increase of 96% and 93% at the end of the loading and unloading processes, respectively, which is acceptable according to previous studies. In addition, the distribution of stress in the artery, plaque, and stent and the phenomena of radial and longitudinal recoil, dogboning, and foreshortening of the stent were also investigated. The study revealed that the designed stent could be used as the next generation of polymer stents for vascular diseases in biomedical applications.

Impact of Calcium Eccentricity on the Safety and Effectiveness of Coronary Intravascular Lithotripsy: Pooled Analysis From the Disrupt CAD Studies.

Coronary intravascular lithotripsy (IVL) safely facilitates successful stent implantation in severely calcified lesions. This analysis sought to determine the relative impact of lesion calcium eccentricity on the safety and effectiveness of IVL using high-resolution optical coherence tomography imaging. Individual patient-level data (n=262) were pooled from 4 distinct international prospective studies (Disrupt CAD I, II, III, and IV) and analyzed by an independent optical coherence tomography core laboratory. IVL performance in eccentric versus concentric calcification was analyzed by dividing calcified lesions into quartiles (≤180° [most eccentric], 181°-270°, 271°-359°, and 360° [concentric]) by maximum continuous calcium arc. In the 230 patients with clear imaging field on optical coherence tomography, there were no differences in preprocedure minimum lumen area, diameter stenosis, or maximum calcium thickness. The calcium length and volume index increased progressively with increasing mean and maximum continuous calcium arc (ie, concentricity). Conversely, the minimum calcium thickness decreased progressively with increasing concentricity. Post-procedure, the number of calcium fractures, fracture depth, and fracture width increased with increasing concentricity, with a 4-fold increase in the number of fractures in lesions with 360° of calcium arc compared with ≤180°. This increase in IVL-induced calcium fracture with increasing calcium burden and concentricity facilitated stent expansion and luminal gain such that there were no significant differences across quartiles. IVL induced calcium fractures proportional to the magnitude of coronary artery calcium, including in eccentric calcium, leading to consistent improvements in stent expansion and luminal gain in both eccentric and concentric calcified coronary lesions.

TCT-679 Intravascular Lithotripsy Is Associated With Excellent Stent Expansion and Clinical Outcomes Despite High Calcium Angle and Thickness

TCT-679 Intravascular Lithotripsy Is Associated With Excellent Stent Expansion and Clinical Outcomes Despite High Calcium Angle and Thickness

TCT-291 Stent Expansion in Calcified Coronary Chronic Total Occlusions: The Impact of Different Stent Platforms

TCT-291 Stent Expansion in Calcified Coronary Chronic Total Occlusions: The Impact of Different Stent Platforms

TCT-600 Evaluation of the Stent Parameters Post-PCI (Minimum Stent Area, Stent Expansion Index, and Stent Gradient) and its Relation to Post-PCI Physiological Outcomes Assessed by Intravascular Imaging-Based Ultrasonic Flow Ratio and Optical Flow Ratio: Insights From the ASET JAPAN Trial

TCT-600 Evaluation of the Stent Parameters Post-PCI (Minimum Stent Area, Stent Expansion Index, and Stent Gradient) and its Relation to Post-PCI Physiological Outcomes Assessed by Intravascular Imaging-Based Ultrasonic Flow Ratio and Optical Flow Ratio: Insights From the ASET JAPAN Trial

Middle Aortic Syndrome in an Elderly Patient : Description of a Surgical Case

The middle aortic syndrome is a rare form of presentation of aortic coarctation that represents 0.5-2% of this same entity. It usually presents in the pediatric or young adult population; therefore, the age of this patient is of interest. It mainly affects women with an estimated ratio of 4:1. Renal involvement is the most prevalent, and idiopathic etiology is the most frequent. This pathology presents clinically with hypertension challenging to control along with intermittent claudication. This article comprises the case of an 81-year-old female patient with a history of hypertension, sedentary lifestyle, smoking, osteoporosis, cholecystectomy in 2010, and appendectomy in childhood. On this occasion, the patient had a stenosis of the infrarenal abdominal aorta and a simultaneous superficial femoral artery lesion and was treated in a hybrid approach with a balloon expandable stent and a suprapatellar femoral-popliteal bypass.

Crack the rock: the role of coronary lithotripsy for heavy calcified lesions

Since the first balloon angioplasty 40 years ago, percutaneous coronary interventions (PCI) applicability continues to expand, even in the context of complex coronary anatomies, previously considered unsuitable for PCI. A very challenging scenario for PCI is the treatment of heavily calcified coronary stenosis that is associated with early complications and late adverse events. Countless tools and techniques have been introduced to treat calcified coronary stenosis, and among these, a new and promising technique obtained from lithotripsy technology employed for the treatment of uretero-renal calculi has been introduced: the intravascular lithotripsy (IVL). IVL utilizes acoustic shockwaves in a balloon-based delivery system that induces calcium fractures, facilitating stent advancement and expansion. This review aims to describe the device used for IVL, the results of clinical studies published, and the possible clinical use.

Direct Comparison of Rotational vs Orbital Atherectomy for Calcified Lesions Guided by Optical Coherence Tomography

BackgroundThere are several retrospective studies comparing rotational atherectomy (RA) and orbital atherectomy (OA), but all percutaneous coronary interventions (PCIs) in those studies were not performed under intracoronary imaging guidance. ObjectivesThis study sought to compare the efficacy and safety of optical coherence tomography (OCT)-guided PCI with RA vs OA. MethodsThe DIRO (To directly compare RA and OA for calcified lesions, a prospective randomized trial) trial was conducted. We enrolled patients with de novo calcified lesions (arc >180°) assessed by OCT or angiographically moderate or severe calcifications if the OCT catheter could not cross the lesion before any intervention. Eligible patients were randomly 1:1 allocated to lesion preparation with RA vs OA. Stent expansion was defined as the minimum stent area divided by the distal reference area multiplied by 100. Tissue modification was assessed using preatherectomy and postatherectomy OCT images. Procedural outcomes including periprocedural myocardial infarctions were evaluated. Furthermore, clinical events and vascular healing evaluated by OCT at 8 months postprocedure were assessed. ResultsThe stent expansion was significantly greater in the RA group vs the OA group (99.5% vs 90.6%; P = 0.02). The maximum atherectomy area was significantly larger in the RA group than in the OA group (1.34 [IQR: 1.02-1.89] mm2 vs 0.83 [IQR: 0.59-1.11] mm2; P = 0.004). The procedural outcomes and clinical events at 8 months did not differ between the groups. The vascular healing was sufficient in both groups. ConclusionsThe prospective randomized DIRO trial revealed that RA could produce a more favorable tissue modification, which may lead to a larger stent expansion than OA in heavily calcified lesions.

Test methods for evaluation of balloon expandable vascular stents – measurement of radial strength and stiffness

Abstract The radial strength of balloon expandable stents represents a key property for a successful recanalization of sclerotic blood vessels. This study focuses on the most commonly used method for investigation of radial strength and radial stiffness via segmented head test setup. A custom made user software was used for evaluation of the radial force curves considering requirements of international standards such as ASTM F3067. Contributing factors during measurement such as friction and test setup deformation as well as the single cycle and multi cycle approach were addressed and discussed.

SYNTAX Score and 1-Year Outcomes in the OPTIVUS-Complex PCI Study Multivessel Cohort

The optimal revascularization strategy in patients with multivessel disease and intermediate SYNTAX score (SS) has not been fully elucidated. This study aimed to investigate the clinical outcomes of optimal intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) stratified by SS. This was a substudy of the OPTIVUS-Complex PCI study Multivessel Cohort, which aimed to meet the prespecified criteria for optimal stent expansion after IVUS-guided PCI. A total of 1,005 patients were divided into 3 groups according to SS: low, ≤22; intermediate, 23 to 32; and high, ≥33. The primary end points were major adverse cardiac and cerebrovascular events (MACCE) defined as a composite of death, myocardial infarction, stroke, or coronary revascularization. The cumulative 1-year incidence of the primary end point was significantly higher in patients with high SS than in those with intermediate or low SS (25.0%, 10.9%, and 9.5%, respectively; p=0.003). This difference was mainly caused by the incidence of coronary revascularization. In the multivariable Cox proportional hazards models, the excess risk of patients with high versus low SS remained significant for the primary end point (hazard ratio 3.19, 95% confidence interval 1.65 to 6.16, p <0.001), whereas the excess risk of patients with intermediate versus low SS was no longer significant (hazard ratio 1.20, 95% confidence interval 0.72 to 2.01, p=0.46). After IVUS-guided multivessel PCI, patients with intermediate SS had a similar 1-year risk of MACCE to that of patients with low SS, whereas patients with high SS had a higher 1-year risk of MACCE than those with low SS.

Calcium evaluation using coronary computed tomography in combination with optical coherence tomography.

Optical coherence tomography (OCT) can assess calcium thickness, a key factor for predicting good stent expansion; however, it underestimates coronary calcium severity due to its penetration limitation. This study aimed to evaluate computed tomography (CT) and OCT images to assess calcification. We investigated 25 left anterior descending arteries of 25 patients, using coronary CT and OCT, and assessed their calcification. Of the 25 vessels, 1811 pairs of CT and OCT cross-sectional images were co-registered. Of the 1811 cross-sectional CT images, calcification was not detectable in 256 (14.1%) of the corresponding OCT images due to limited penetration. In the 1555 OCT calcium-detectable images, the maximum calcium thickness was not detectable in 763 (49.1%) images compared to the CT images. In CT images of slices corresponding to undetected calcium in OCT images, the angle, thickness, and maximum density of calcium were significantly smaller compared to slices corresponding to detected calcium in OCT. Calcium with an undetectable maximum thickness in the corresponding OCT image had a significantly greater calcium angle, thickness, and density than calcium with a detectable maximum thickness. There was an excellent correlation between CT and OCT with respect to calcium angle ( R= 0.82, P < 0.001). The calcium thickness on the OCT image had a stronger correlation with the maximum density on the corresponding CT image (R = 0.73, P < 0.001) than with the calcium thickness on the CT image (R = 0.61, P < 0.001). Cross-sectional CT imaging allows for pre-procedural assessment of calcium morphology and severity and could complement the lack of information on calcium severity in OCT-guided percutaneous coronary intervention.

How Should I Treat Under Expanded Coronary Stents Due to Severe Coronary Calcification?

With aging society, one of the more challenging obstacles in percutaneous coronary interventions (PCI) are calcified coronary lesions (CAC). CAC may impede stent delivery; limit balloon and stent expansion, which result in lower minimal stent area (MSA), cause uneven drug distribution, and even hinder wire advancement [1-4]. Lower MSA and stent under-expansion are associated with adverse outcomes, including stent thrombosis, restenosis, and major adverse cardiac outcomes (MACE) [5,6].

Accuracy of IVUS-Based Machine Learning Segmentation Assessment of Coronary Artery Dimensions and Balloon Sizing

BackgroundAccurate intravascular ultrasound (IVUS) measurements are important in IVUS-guided percutaneous coronary intervention optimization by choosing the appropriate device size and confirming stent expansion. ObjectivesThe purpose of this study was to assess the accuracy of machine learning (ML) automatic segmentation of coronary artery vessel and lumen dimensions and balloon sizing. MethodsUsing expert analysis as the gold standard, ML segmentation of 60 MHz IVUS images was developed using 8,076 IVUS cross-sectional images from 234 patients, which were randomly split into training (83%) and validation (17%) data sets. The performance of ML segmentation was then evaluated using an independent test data set (437 images from 92 patients). The endpoints were the agreement rate between ML vs experts’ measurements for appropriate balloon size selection, and lumen and acute stent areas. Appropriate balloon size was determined by rounding down from the mean vessel diameter or rounding up from the mean lumen diameter to the next balloon size. The difference of lumen area ≥0.5 mm2 was considered as clinically significant. ResultsML model segmentation correlated well with experts’ segmentation for training data set with a correlation coefficient of 0.992 and 0.993 for lumen and vessel areas, respectively. The agreement rate in lumen and acute stent areas was 85.5% and 97.0%, respectively. The agreement rate for appropriate balloon size selection was 70.6% by vessel diameter only and 92.4% by adding lumen diameter. ConclusionsML model IVUS segmentation measurements were well-correlated with those of experts and selected an appropriate balloon size in more than 90% of images.

A Systematic Review and Meta-Analysis Including 354 Patients from 13 Studies of Intravascular Lithotripsy for the Treatment of Underexpanded Coronary Stents

Calcified coronary plaque (CCP) represents a challenging scenario for interventional cardiologists. Stent underexpansion (SU), often associated with CCP, can predispose to stent thrombosis and in-stent restenosis. To date, SU with heavily CCP can be addressed using very high-/high-pressure noncompliant balloons, off-label rotational atherectomy/orbital atherectomy, excimer laser atherectomy, and intravascular lithotripsy (IVL). In this meta-analysis, we investigated the success rate of IVL for the treatment of SU because of CCP. Studies and case-based experiences reporting on the use of IVL strategy for treatment of SU were included. The primary end point was IVL strategy success, defined as the adequate expansion of the underexpanded stent. A metanalysis was performed for the main focuses to calculate the proportions of procedural success rates with corresponding 95% confidence intervals (CIs). Random-effects models weighted by inverse variance were used because of clinical heterogeneity. This meta-analysis included 13 studies with 354 patients. The mean age was 71.3years (95% CI 64.9 to 73.1), and 77% (95% CI 71.2% to 82.4%) were male. The mean follow-up time was 2.6months (95% CI 1 to 15.3). Strategy success was seen in 88.7% (95% CI 82.3 to 95.1) of patients. The mean minimal stent area was reported in 6 studies, the pre-IVL value was 3.4mm2 (95% CI 3 to 3.8), and the post-IVL value was 6.9mm2 (95% CI 6.5 to 7.4). The mean diameter stenosis (percentage) was reported in 7 studies, the pre-IVL value was 69.4% (95% CI 60.7 to 78.2), and the post-IVL value was 14.6% (95% CI 11.1 to 18). The rate of intraprocedural complications was 1.6% (95% CI 0.3 to 2.9). In conclusion, the "stent-through" IVL plaque modification technique is a safe tool to treat SU caused by CCP, with a high success rate and a very low incidence of complications.