Excimer laser coronary angioplasty combined with drug-coated balloon in the treatment of in-stent restenosis

OBJECTIVES

The aim of this study is to investigate the safety and efficacy of excimer laser coronary angioplasty (ELCA) combined with drug-coated balloons (DCBs) in the treatment of in-stent restenosis (ISR), and to explore whether the contrast injection technique would improve the neointimal tissue ablation of ELCA.

METHODS

We studied patients diagnosed with ISR between January 2019 and October 2022 at two medical centers. These patients underwent DCB angioplasty guided by optical coherence tomography (OCT). Based on whether ELCA was performed before DCB treatment, patients were categorized into two groups: the ELCA + DCB group and the DCB group. All patients underwent clinical follow-up 1 year after the procedure. The primary endpoint was the 1-year rate of target lesion revascularization (TLR), which was defined as any repeat percutaneous intervention or bypass surgery on the target vessel conducted to address restenosis or other complications related to the target lesion. The secondary endpoints including immediate luminal gain (ΔMLA, defined as the difference in minimum lumen area before and after the intervention).

RESULTS

A total of 85 lesions in 75 patients were included. The mean age of the study population was 64.2 ± 12.0 years, with 81.3% male. Baseline clinical characteristics were well-balanced, and procedural success was 100% in both groups. The ELCA + DCB group (n = 24) exhibited a greater ΔMLA compared to the DCB group (n = 61) (3.57 ± 0.79 mm² vs. 2.50 ± 1.06 mm², [95% confidence interval, CI: 0.57-1.69], p < 0.001), The reduction in 1-year TLR was more frequently observed in patients from the ELCA + DCB group compared to the DCB group (hazard ratio 0.33 [95% CI: 0.11-0.99]; log-rank p = 0.048). The exploratory analysis showed that ELCA with contrast infusion is associated with greater acute lumen gain compared to ELCA with saline infusion (p < 0.001).

CONCLUSIONS

The combination of ELCA and DCB is a safe and effective treatment strategy for in-stent stenosis. Additionally, compared with saline injection, ELCA with contrast injection is associated with greater acute lumen gain. However, the optimal contrast agent concentration and long-term outcome of the contrast injection technique need confirmation through larger sample sizes and prospective studies.

Intravascular imaging in the diagnosis and management of patients with suspected intracoronary pathologies: A CJC White Paper

Intravascular imaging has become an integral part of the diagnostic and management strategies for intracoronary pathologies. This White Paper summarizes current evidence and its implications on the use of intravascular imaging in interventional cardiology practice. The areas addressed are planning and optimization of percutaneous coronary intervention, management of stent failure, and evaluation of ambiguous coronary lesions and myocardial infarction with non-obstructive coronary disease (MINOCA). Findings are presented following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system in an expert consensus process involving a diverse Writing group and vetted by a Review group. Expert consensus was achieved around nine statements. Use of intravascular imaging in guiding percutaneous revascularization is supported by high quality evidence, particularly for lesions with increased risk of recurrent events or stent failure. Specific considerations for intravascular imaging guidance of intervention in left main lesions, chronic occlusion lesions as well as patients at high risk of contrast nephropathy are explored. Use of intravascular imaging to identify pathologies associated with stent failure and guide repeat intervention, resolve ambiguities in lesion assessment and establish diagnoses in patients presenting with MINOCA is supported by moderate to low quality evidence. Each topic is accompanied by clinical pointers to aid the practicing interventional cardiologist in implementation of the White paper findings. The findings of this White Paper will help to guide the utilization of intravascular imaging towards those situations in which the balance of efficacy, safety and cost are most optimal.

Objective Methods to Assess Aorto-Iliac Calcifications: A Systematic Review

Vascular calcifications in aorto-iliac arteries are emerging as crucial risk factors for cardiovascular diseases (CVDs) with profound clinical implications. This systematic review, following PRISMA guidelines, investigated methodologies for measuring these calcifications and explored their correlation with CVDs and clinical outcomes. Out of 698 publications, 11 studies met the inclusion criteria. In total, 7 studies utilized manual methods, while 4 studies utilized automated technologies, including artificial intelligence and deep learning for image analyses. Age, systolic blood pressure, serum calcium, and lipoprotein(a) levels were found to be independent risk factors for aortic calcification. Mortality from CVDs was correlated with abdominal aorta calcification. Patients requiring reintervention after endovascular recanalization exhibited a significantly higher volume of calcification in their iliac arteries. Conclusions: This review reveals a diverse landscape of measurement methods for aorto-iliac calcifications; however, they lack a standardized reproducibility assessment. Automatic methods employing artificial intelligence appear to offer broader applicability and are less time-consuming. Assessment of calcium scoring could be routinely employed during preoperative workups for risk stratification and detailed surgical planning. Additionally, its correlation with clinical outcomes could be useful in predicting the risk of reinterventions and amputations.

Drug-Eluting Balloons in Calcified Coronary Lesions: A Meta-Analysis of Clinical and Angiographic Outcomes

Background: The usefulness of drug-eluting balloons (DEBs) has not been fully elucidated in calcified coronary lesions (CCLs). This meta-analysis aimed to evaluate the efficacy of DEBs compared to a drug-eluting stent (DES) in this setting. Methods: PubMed, EMBASE and Cochrane were searched through December 2023. The primary endpoint was 12 months major adverse cardiac events (MACE). Secondary endpoints included clinical outcomes and angiographic results after PCI and at a 12-month follow-up. Results: Five studies and a total of 1141 patients with 1176 coronary lesions were included. Overall, the DEB was comparable to DES in MACE (RR = 0.86, 95% CI: 0.62-1.19, p = 0.36), cardiac death (RR = 0.59, 95% CI: 0.23-1.53, p = 0.28), myocardial infarction (RR = 0.89, 95% CI: 0.25-3.24, p = 0.87) and target lesion revascularization (RR = 1.1, 95% CI: 0.68-1.77, p = 0.70). Although the DEB was associated with worse acute angiographic outcomes (acute gain; MD = -0.65, 95% CI: -0.73, -0.56 and minimal lumen diameter; MD = -0.75, 95% CI: -0.89, -0.61), it showed better results at 12 months follow-up (late lumen loss; MD = -0.34, 95% CI: -0.62, -0.07). Conclusions: This meta-analysis showed that the DEB strategy is comparable to DES in the treatment of CCLs in terms of clinical outcomes. Although the DEB strategy had inferior acute angiographic results, it may offer better angiographic results at follow-up.

A novel approach to saline/contrast delivery in excimer laser coronary atherectomy (ELCA) to enhance efficacy: MAXCon ELCA technique

The advent of excimer laser coronary atherectomy (ELCA) nearly four decades ago heralded a novel way to treat complex lesions, both coronary and peripheral, which were previously untraversable and thus untreatable. These complex lesions include heavily calcified lesions, ostial lesions, bifurcation lesions, chronic total occlusions, in-stent restenosis (including stent underexpansion), and degenerative saphenous vein grafts. We discuss the technology of ELCA, its indications, applications, and complications, and suggest the "MAXCon ELCA" technique for better outcomes without increased risk. Lastly, we present a case of MAXCon ELCA effectively treating a complex lesion.

Current Management of In-Stent Restenosis

In-stent restenosis (ISR) remains the primary cause of target lesion failure following percutaneous coronary intervention (PCI), resulting in 10-year incidences of target lesion revascularization at a rate of approximately 20%. The treatment of ISR is challenging due to its inherent propensity for recurrence and varying susceptibility to available strategies, influenced by a complex interplay between clinical and lesion-specific conditions. Given the multiple mechanisms contributing to the development of ISR, proper identification of the underlying substrate, especially by using intravascular imaging, becomes pivotal as it can indicate distinct therapeutic requirements. Among standalone treatments, drug-coated balloon (DCB) angioplasty and drug-eluting stent (DES) implantation have been the most effective. The main advantage of a DCB-based approach is the avoidance of an additional metallic layer, which may otherwise enhance neointimal hyperplasia, provide the substratum for developing neoatherosclerosis, and expose the patient to a persistently higher risk of coronary ischemic events. On the other hand, target vessel scaffolding by DES implantation confers relevant mechanical advantages over DCB angioplasty, generally resulting in larger luminal gain, while drug elution from the stent surface ensures the inhibition of neointimal hyperplasia. Nevertheless, repeat stenting with DES also implies an additional permanent metallic layer that may reiterate and promote the mechanisms leading to ISR. Against this background, the selection of either DCB or DES on a patient- and lesion-specific basis as well as the implementation of adjuvant treatments, including cutting/scoring balloons, intravascular lithotripsy, and rotational atherectomy, hold the potential to improve the effectiveness of ISR treatment over time. In this review, we comprehensively assessed the available evidence from randomized trials to define contemporary interventional treatment of ISR and provide insights for future directions.

TRIM27 Promotes Endothelial Progenitor Cell Apoptosis in Patients with In-Stent Restenosis by Ubiquitinating TBK1

Approximately 2-10% in-stent restenosis (ISR) may occur following percutaneous coronary intervention (PCI) despite the use of modern drug-eluting stents (DES); thus, our study aimed to explore the effects of tripartite motif-containing (TRIM) 27 on ISR and the underlying mechanism. For this purpose, a total of 42 patients undergoing coronary angiography who had prior coronary angiography with DES implantation were recruited. Endothelial progenitor cells (EPCs) markers (defined as CD34 and vascular endothelial growth factoreceptor-2 (VEGFR-2)) in peripheral blood were measured to asses the circulating EPC level. The TRIM family-related gene expressions were detected by reverse transcription-quantitative polymerase chain reaction. Results suggested that ISR patients had reduced CD34+VEGFR-2+ and increased apoptosis rate of EPCs, along with upregulated TRIM27 and TRIM37 and downregulated TRIM28. TRIM27 promoted and TBK1 inhibited the apoptosis rate of EPCs. Mechanically, TRIM27 interacted with TBK1 to ubiquitinate TBK1 in in vitro study. In summary, TRIM27 promoted the progression of ISR in patients after PCI by ubiquitinating TBK1, which might provide novel ideas for the clinical treatment of ISR.

Comparison of intravascular lithotripsy and rotational atherectomy for the treatment of heavily calcified coronary lesions: the STIFF (Stenoses with calcificaTIon treated with angioplasty eFFected with dedicated interventional tools) study

BACKGROUND

Percutaneous coronary interventions in heavily calcified coronary lesions are associated with technical difficulties and the worse prognosis. Lesion preparation is important to reduce complications and improve outcomes. The aim of this study is to compare the results of rotational atherectomy (RA) and intravascular lithotripsy (IVL) at achieving optimal stent implantation using intravascular ultrasound criteria.

METHODS

Retrospective, single-center study comparing patients with heavily calcified coronary lesions that underwent percutaneous coronary interventions using RA or IVL.

RESULTS IN TOTAL

25 patients (13 in the RA group and 12 in the IVL group) were included. Reference vessel diameter was similar between the groups [2.59 (2.51-3.63) mm in the RA group vs. 2.79 (2.59-3.16) mm in the IVL group; P = 0.89], as were minimal lumen area [1.02 (0.80-1.23) mm vs. 1.40 (1.01-1.40) mm; P = 0.43] and diameter stenosis [60.4% (52.3-72.3) vs. 56.1% (47.8-61.3); P = 0.56). The final minimal lumen area was significantly larger in the IVL group [7.6 mm2 (5.8-8.6) vs. 5.4 mm2 (4.5-6.2); P = 0.01] as were lumen area gain [4.1 mm2 (2.6-5.9) vs. 2.3 mm2 (1.4-3.6); P = 0.01] and final stent volume [491.2 mm3 (372.2-729.8) vs. 326.2 mm3 (257.1-435.4); P = 0.03]. In the RA group, 69.2% of the patients achieved the preestablished intravascular ultrasound-based criteria for successful stent implantation, vs. 100% of the patients in the IVL group (P = 0.04).

CONCLUSION

Patients in the IVL group achieved the Intravascular Ultrasound Versus Angiography-Guided Drug-Eluting Stent Implantation trial criteria of successful stent implantation more frequently than those treated with RA.

Clinical Outcome of Paclitaxel-Coated Balloon Angioplasty Versus Drug-Eluting Stent Implantation for the Treatment of Coronary Drug-Eluting Stent In-Stent Chronic Total Occlusion

AIMS

In-stent chronic total occlusion (IS-CTO) represents a unique challenge for percutaneous coronary intervention. Whether the optimal treatment for IS-CTO is angioplasty with paclitaxel-coated balloons (PCBs) or repeat stenting with drug-eluting stents (DESs) is unclear. We aimed to evaluate the long-term clinical outcome of PCB angioplasty and DES repeat stenting for DES IS-CTO.

METHODS

We retrospectively included patients with DES IS-CTO who underwent successful PCB angioplasty or DES repeat stenting from January 2016 to December 2019. The primary endpoints were major adverse cardiac events (MACEs), including cardiac death, myocardial infarction, and target lesion revascularization (TLR). Cox proportional hazards model was performed to compare the risk of MACEs between PCB angioplasty and DES repeat stenting, and to further explore the prognostic factors of patients with DES IS-CTO.

RESULTS

A total of 214 patients with DES IS-CTO were enrolled: 78 patients (36.4%) treated with PCB and 136 patients (63.6%) treated with DES respectively. The median follow-up was 1160 days, and MACEs were observed in 28.2% of patients with PCB angioplasty versus 26.5% of patients with DES repeat stenting (P = 0.784), mainly driven by TLR (21.8% vs. 19.9%, P = 0.735). There was no significant difference in the risk of MACEs between the PCB group and the DES group (hazard ratio [HR] 1.25, 95% confidence interval [CI] 0.64-2.46, P = 0.512). Multivariate Cox analysis revealed that chronic kidney disease and ≥ 3 stent layers in the lesion were independent predictors of MACEs, while switching to another antiproliferative drug was an independent protective factor (all P < 0.05).

CONCLUSIONS

PCB angioplasty was an effective alternative treatment strategy for DES IS-CTO, which had similar long-term outcomes to DES repeat stenting in contemporary practice, but both were accompanied by a high rate of long-term MACEs. Improving the poor prognosis of patients with DES IS-CTO remains a challenge.

Comparison of Recurrent With First-Time In-Stent Restenosis

Recurrent in-stent restenosis (Re-ISR) remains a therapeutic challenge. We aimed to investigate the clinical characteristics, treatment, and long-term outcomes in patients with Re-ISR compared with those with first-time ISR (First-ISR). This retrospective study consecutively enrolled patients who underwent percutaneous coronary intervention (PCI) for ISR in Fuwai Hospital between January 2017 and December 2018. Re-ISR was defined as a second event of ISR after a previous successful treatment of the ISR lesion. The primary outcome was defined as a composite of all-cause death, spontaneous myocardial infarction, and repeat revascularization. A total of 2,006 patients (2,154 lesions) with ISR underwent successful PCI were enrolled and categorized into 2 groups: the Re-ISR group (246 patients/259 lesions) and the First-ISR group (1,760 patients/1,895 lesions). During a mean follow-up of 36 months, the primary outcomes occurred in 80 patients (32.5%) in the Re-ISR group and 349 patients (19.3%) in the First-ISR group (p <0.001 by log-rank test), major driven by spontaneous myocardial infarction (4.9% vs 2.7%, p = 0.049) and repeat revascularization (30.1% vs 16.5%, p <0.001). The multivariable Cox regression analysis revealed that Re-ISR was independently associated with a higher rate of major adverse cardiovascular events (adjusted hazard ratio 1.88, 95% confidence interval 1.39 to 2.53, p <0.001) and repeated revascularization (adjusted hazard ratio 2.09, 95% confidence interval 1.53 to 2.84, p <0.001). The relation remained consistent after the propensity score analysis. In conclusion, in the present cohort of patients who underwent PCI for ISR, Re-ISR was significantly associated with a higher risk of long-term outcomes than First-ISR.

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 71.3 years (95% CI 64.9 to 73.1), and 77% (95% CI 71.2% to 82.4%) were male. The mean follow-up time was 2.6 months (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 3.4 mm2 (95% CI 3 to 3.8), and the post-IVL value was 6.9 mm2 (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.

Optical Coherence Tomography Findings in Patients Presenting With In-Stent Restenosis: A Prospective Observational Study of Patterns of Neointimal Hyperplasia and Associated Risk Factors

Introduction Morphological features of neointimal tissue play a pivotal role in the pathophysiology of in-stent restenosis (ISR) after percutaneous coronary intervention (PCI). This study was designed to qualitatively and quantitatively assess neointimal characteristics of lesions using optical coherence tomography (OCT) in patients presenting with ISR.  Methods This was a single-center, prospective, observational study performed at a tertiary-care center in India. Patients diagnosed with stable angina and acute coronary syndrome with post-procedural angiographically documented restenosis (>50%) were included. Results A total of 34 patients with ISR were studied. Neointimal hyperplasia was classified as (i) homogenous group (n = 18) and (ii) non-homogenous group (n = 16). Fourteen (77.8%) diabetics belonged to the homogenous group. Predominant plaque characteristics such as neoatherosclerosis, cholesterol crystals, and calcium were documented in 14 (77.8%), 12 (66.7%), and 11 (61.1%) patients in the homogenous group and 10 (62.5%), 10 (62.5%), and 9 (56.2%) patients in the non-homogenous group, respectively. Unexpanded stent struts were identified in 11 (61.1%) and 11 (68.8%) patients in the homogenous and non-homogenous groups, respectively. Mean strut thickness was 93.73 ± 31.03 µm and 83.54 ± 18.0 µm, ISR was 72.50 ± 15.93% and 65.37 ± 21.69%, the neointimal thickness was 588.06 ± 167.82 μm and 666.25 ± 218.05 μm, and neointimal hyperplasia was 54.54 ± 11.23% and 59.26 ± 8.86% in the homogenous and non-homogenous groups, respectively. Conclusion Neoatherosclerosis and stent underexpansion were predominantly observed in our study and only diabetes was found to be significantly associated with homogenous neointimal hyperplasia.

In-vivo assessment of vascular injury for the prediction of in-stent restenosis

BACKGROUND

Despite optimizations of coronary stenting technology, a residual risk of in-stent restenosis (ISR) remains. Vessel wall injury has important impact on the development of ISR. While injury can be assessed in histology, there is no injury score available to be used in clinical practice.

METHODS

Seven rats underwent abdominal aorta stent implantation. At 4 weeks after implantation, animals were euthanized, and strut indentation, defined as the impression of the strut into the vessel wall, as well as neointimal growth were assessed. Established histological injury scores were assessed to confirm associations between indentation and vessel wall injury. In addition, stent strut indentation was assessed by optical coherence tomography (OCT) in an exemplary clinical case.

RESULTS

Stent strut indentation was associated with vessel wall injury in histology. Furthermore, indentation was positively correlated with neointimal thickness, both in the per-strut analysis (r = 0.5579) and in the per-section analysis (r = 0.8620; both p ≤ 0.001). In a clinical case, indentation quantification in OCT was feasible, enabling assessment of injury in vivo.

CONCLUSION

Assessing stent strut indentation enables periprocedural assessment of stent-induced damage in vivo and therefore allows for optimization of stent implantation. The assessment of stent strut indentation might become a valuable tool in clinical practice.

Prevalence, Management and Outcomes of Percutaneous Coronary Intervention for Coronary In-Stent Restenosis: Insights From the France PCI Registry

BACKGROUND

Despite the evolution of stent technology, there is a non-negligible risk of in-stent restenosis (ISR) after Percutaneous coronary intervention (PCI). Large-scale registry data on the prevalence and clinical management of ISR is lacking.

METHODS

The aim was to describe the epidemiology and management of patients with ≥1 ISR lesions treated with PCI (ISR PCI). Data on characteristics, management and clinical outcomes were analyzed for patients undergoing ISR PCI in the France-PCI all-comers registry.

RESULTS

Between January 2014 and December 2018, 31,892 lesions were treated in 22,592 patients, 7.3 % of whom underwent ISR PCI. Patients undergoing ISR PCI were older (68.5 vs 67.8; p < 0.001), and more likely to have diabetes (32.7 % vs 25.4 %, p < 0.001), chronic coronary syndrome or multivessel disease. ISR PCI concerned drug eluting stents (DES) ISR in 48.8 % of cases. Patients with ISR lesions were more frequently treated with DES than drug eluting balloon or balloon angioplasty (74.2 %, 11.6 % and 12.9 %, respectively). Intravascular imaging was rarely used. At 1 year, patients with ISR had higher target lesion revascularization rates (4.3 % vs. 1.6 %; HR 2.24 [1.64-3.06]; p < 0.001).

CONCLUSIONS

In a large all-comers registry, ISR PCI was not infrequent and associated with worse prognosis than non-ISR PCI. Further studies and technical improvements are warranted to improve the outcomes of ISR PCI.

Drug-coated balloon therapy is more effective in treating late drug-eluting stent in-stent restenosis than the early occurring one-a systematic review and meta-analysis

Drug-eluting stent in-stent restenosis (DES-ISR) remains one of the important assignments to be resolved in interventional cardiology, as it is present in 5%-10% of total percutaneous coronary intervention cases. Drug-coated balloon (DCB) utilization is promising, as it comes with long-term protection from recurrent restenosis in optimal conditions without the hazard of higher risk for stent thrombosis and in-stent restenosis. We aim to reduce the need for recurrent revascularization in DES-ISR, specifying the population in which the DCB therapy should be used. In this meta-analysis, the results of studies containing data on the time frame between drug-eluting stent implantation and the clinical presentation of in-stent restenosis and concomitant drug-coated balloon treatment were summarized. A systematic search was performed in Medline, Central, Web of Science, Scopus and Embase databases on November 11th, 2021. The QUIPS tool was used to assess the risk of bias in the included studies. The occurrence of a major cardiac adverse events (MACE) composite endpoint, containing target lesion revascularization (TLR), myocardial infarction, and cardiac death, and each of these separately, was assessed at 12 months after the balloon treatment. Random effects meta-analysis models were used for statistical analysis. Data of 882 patients from four studies were analyzed. Across the included studies, a 1.68 OR (CI 1.57-1.80, p < 0.01) for MACE and a 1.69 OR (CI 1.18-2.42 p < 0.01) for TLR were observed, both in favor of late DES-ISR. The main limitation of the study is the relatively low patient number. Nevertheless, this analysis shows the first statistically significant results for the effect of DCB treatment in the early or late presentation of DES-ISR. As to date, intravascular imaging (IVI) remains limitedly accessible, other landmarks as the time frame of in-stent restenosis development are to be pursued to advance therapeutic outcomes. In consideration of other biological, technical and mechanical factors, time frame of occurrence as a prognostic factor could reduce the burden of recurrent revascularization in patients at an already high risk. Systematic Review Registration: identifier [CRD42021286262].

Management of failed stenting of the unprotected left main coronary artery

Percutaneous coronary intervention (PCI) is increasingly accepted as treatment for unprotected left main coronary artery (ULMCA) disease especially in those patients who are unsuitable for cardiac surgery. Treatment of any stent failure is associated with increased complexity and worse clinical outcomes when compared with de novo lesion revascularization. Intracoronary imaging has provided new insight into mechanisms of stent failure and treatment options have developed considerably over the last decade. There is paucity of evidence on the management strategy for stent failure in the specific setting of ULMCA. Treating any left main with PCI requires careful consideration and consequently treatment of failed stents in ULMCA is complex and provides unique challenges. Consequently, we provide an overview of ULMCA stent failure, proposing a tailored algorithm to guide best management and decision in daily clinical practice, with a special focus on intracoronary imaging characterization of causal mechanisms and specific technical and procedural considerations.

Intravascular Imaging for Guiding In-Stent Restenosis and Stent Thrombosis Therapy

Advances in stent technology and the design of endovascular devices with thinner struts, anti-inflammatory and antithrombotic polymers, and better drug kinetics have enhanced the safety and efficacy of the second-generation drug-eluting stents and broadened their use in the therapy of high-risk patients and complex anatomies. However, despite these developments, in-stent restenosis and stent thrombosis remain the Achilles' heel of percutaneous coronary intervention, with their cumulative incidence reaching up to 10% at 5 years following percutaneous coronary intervention. The treatment of stent failure poses challenges and is associated with a worse prognosis than conventional percutaneous coronary intervention. Several studies have recently highlighted the value of intravascular imaging in identifying causes of stent failure, underscored its role in treatment planning, and registries have shown that its use may be associated with better clinical outcomes. The present review aims to summarize the evidence in the field; it discusses the value of intravascular imaging in identifying the mechanisms of in-stent restenosis and stent thrombosis in assessing the morphological characteristics of neointima tissue that appears to determine long-term outcomes in evaluating procedural results, and presents the findings of studies supporting its value in guiding therapy in stent failure.

Coronary lithotripsy for the treatment of underexpanded stents: the international & multicentre CRUNCH registry

BACKGROUND

Stent underexpansion increases the risk of cardiac adverse events. At present, there are limited options to treat refractory stent underexpansion. In this context, the intravascular lithotripsy (IVL) system might be a safe and effective strategy.

AIMS

We aimed to evaluate the safety and efficacy of IVL in addressing resistant stent underexpansion due to heavy underlying calcification.

METHODS

This was an international multicentre registry including patients receiving IVL therapy to treat stent underexpansion from December 2017 to August 2020. Angiographic and intracoronary imaging data were collected. The efficacy endpoint was device success (technical success with a final percentage diameter stenosis <50%). The safety endpoint was in-hospital major adverse cardiac events (MACE).

RESULTS

Seventy patients were included, the mean age was 73±9.2 years and 76% were male. The median time from stent implantation to IVL therapy was 49 days (0-2,537). Adjuvant treatment with non-compliant balloon dilatations pre- and post-IVL was performed in 72.3% and 76.8% of patients, respectively, and additional stenting was performed in 22.4%. Device success was 92.3%. Minimum lumen diameter increased from 1.49±0.73 mm to 2.41±0.67 mm (p<0.001) and stent expansion increased by 124.93±138.19% (p=0.016). No IVL-related procedural complications or MACE were observed. The use of bailout IVL therapy directly after stenting and the presence of ostial underexpanded lesions negatively predicted lumen diameter gain.

CONCLUSIONS

Coronary lithotripsy is safe and effective in increasing lumen and stent dimensions in underexpanded stents secondary to heavily calcified lesions.

Prevalence and Impact of Neoatherosclerosis on Clinical Outcomes After Percutaneous Treatment of Second-Generation Drug-Eluting Stent Restenosis

BACKGROUND

Clinical and morphological factors associated with lipidic versus calcified neoatherosclerosis within second-generation drug-eluting stents and the impact of lipidic versus calcified neoatherosclerosis on long-term outcomes after repeat intervention have not been well studied.

METHODS

A total of 512 patients undergoing optical coherence tomography before percutaneous coronary intervention for second-generation drug-eluting stents in-stent restenosis were included. Neoatherosclerosis was defined as lipidic or calcified neointimal hyperplasia in ≥3 consecutive frames or ruptured lipidic neointimal hyperplasia. The primary outcome was target lesion failure (cardiac death, target vessel myocardial infarction, definite stent thrombosis, or clinically driven target lesion revascularization).

RESULTS

The overall prevalence of neoatherosclerosis was 28.5% (146/512): 56.8% lipidic, 30.8% calcified, and 12.3% both lipidic and calcific. The prevalence increased as a function of time from stent implantation: 20% at 1 to 3 years, 30% at 3 to 7 years, and 75% >7 years. Renal insufficiency, poor lipid profile, and time from stent implantation were associated with lipidic neoatherosclerosis, whereas severe renal insufficiency, female sex, and time from stent implantation were associated with calcified neoatherosclerosis. Multivariable Cox regression revealed that female sex and lipidic neoatherosclerosis were associated with more target lesion failure, whereas stent age and final minimum lumen diameter after reintervention were related to lower target lesion failure. Calcified neoatherosclerosis was not related to adverse events after reintervention for in-stent restenosis given a large enough minimum lumen diameter was achieved.

CONCLUSIONS

Lipidic but not calcified neoatherosclerosis was associated with poor subsequent outcomes after repeat revascularization if optimal stent expansion was achieved in lesions with calcified neoatherosclerosis.

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

Coronary In-Stent Restenosis: JACC State-of-the-Art Review

The introduction and subsequent iterations of drug-eluting stent technologies have substantially improved the efficacy and safety of percutaneous coronary interventions. However, the incidence of in-stent restenosis (ISR) and the resultant need for repeated revascularization still occur at a rate of 1%-2% per year. Given that millions of drug-eluting stents are implanted each year around the globe, ISR can be considered as a pathologic entity of public health significance. The mechanisms of ISR are multifactorial. Since the first description of the angiographic patterns of ISR, the advent of intracoronary imaging has further elucidated the mechanisms and patterns of ISR. The armamentarium and treatment strategies of ISR have also evolved over time. Currently, an individualized approach using intracoronary imaging to characterize the underlying substrate of ISR is recommended. In this paper, we comprehensively reviewed the incidence, mechanisms, and imaging characterization of ISR and propose a contemporary treatment algorithm.

Management of in-stent restenosis

In-stent restenosis (ISR) remains the most common cause of stent failure after percutaneous coronary intervention (PCI). Recent data suggest that ISR-PCI accounts for 5-10% of all PCI procedures performed in current clinical practice. This State-of-the-Art review will primarily focus on the management of ISR but will begin by briefly discussing diagnosis and classification. We then move on to detail the evidence base underpinning the various therapeutic strategies for ISR before finishing with a proposed ISR management algorithm based on current scientific data.

Utility of coronary orbital atherectomy with guide-extension system for distally located undilatable in-stent restenosis: A case report

Orbital atherectomy (OA) may be effective in managing undilatable in‐stent restenosis (ISR) despite off‐label indications. We demonstrated that optical frequency domain imaging (OFDI)‐guided OA, with a guide‐extension system was effective even in distally located, undilatable ISR. However, OFDI revealed that inter‐struts calcified neoatherosclerosis remained a challenging issue.

Initial experience of a single referral centre using excimer laser coronary atherectomy-assisted expansion in undilatable stents: Excimer laser in undilatable stents

AIMS

Undilatable stents with severe peri-stent calcification are an important cause of target lesion failure and therapeutic options are limited. We report our initial experience with the safety and efficacy of excimer laser coronary atherectomy (ELCA)-assisted expansion of undilatable stents.

METHODS AND RESULTS

ELCA was performed with saline, blood and contrast-enhanced trains. All lesions were post-dilated at high pressures and treated with a drug-eluting balloon. Thirty-one lesions with undilatable stents were included at a single centre with experienced operators from March 2016 to February 2021. The mean number of prior procedures for in-stent restenosis was three and 14 lesions had multiple layers of stent. Procedural success (>50% increase in minimal stent diameter [MSD]) and adequate stent expansion (MSD >70% of reference vessel diameter) was achieved in all lesions. At six-month follow-up (N=26 lesions), there were six periprocedural myocardial infarctions due to slow flow, two cardiac deaths and one target lesion revascularisation. There were no perforations.

CONCLUSIONS

Our niche experience at a centre with experienced operators demonstrated that ELCA led to larger final lumen and stent dimensions in highly selected patients with undilatable stents and recurrent restenosis at the cost of relatively frequent slow flow.

Treatment of the Carotid In-stent Restenosis: A Systematic Review

Background and Purpose: In-stent restenosis (ISR) after carotid artery stent (CAS) is not uncommon. We aimed to evaluate therapeutic options for ISR after CAS. Methods: We searched PubMed and EMBASE until November 2, 2020 for studies including the treatment for ISR after CAS. Results: In total, 35 studies, covering 1,374 procedures in 1,359 patients, were included in this review. Most cases (66.3%) were treated with repeat CAS (rCAS), followed by percutaneous transluminal angioplasty (PTA) (17.5%), carotid endarterectomy (CEA) (14.3%), carotid artery bypass (1.5%), and external beam radiotherapy (0.4%). The rates of stroke & TIA within the postoperative period were similar in three groups (PTA 1.1%, rCAS 1.1%, CEA 1.5%). CEA (2.5%) was associated with a slightly higher rate of postoperative death than rCAS (0.7%, P = 0.046). Furthermore, the rate of long-term stroke & TIA in PTA was 5.7%, significantly higher than rCAS (1.8%, P = 0.036). PTA (27.8%) was also associated with a significantly higher recurrent restenosis rate than rCAS (8.2%, P = 0.002) and CEA (1.6%, P < 0.001). The long-term stroke & TIA and recurrent restenosis rates showed no significant difference between rCAS and CEA. Conclusions: rCAS is the most common treatment for ISR, with low postoperative risk and low long-term risk. CEA is an important alternative for rCAS. PTA may be less recommended due to the relatively high long-term risks of stroke & TIA and recurrent restenosis.

Additional ablation effect of low-speed rotational atherectomy following high-speed rotational atherectomy on early calcified in-stent restenosis: A case report

Optical frequency domain imaging-guided additional low-speed rotational atherectomy following sufficient high-speed rotational atherectomy for early calcified in-stent restenosis might be a safe and useful option for achieving additional large lumen gains and stent expansion.

Waksman In-Stent Restenosis Classification: A mechanism-based approach to the treatment of restenosis

Despite contemporary advances in stent technology, in-stent restenosis (ISR) remains a common issue following percutaneous coronary intervention. A novel classification system based on underlying mechanism of action of restenosis was recently introduced. The Waksman In-Stent Restenosis Classification characterizes different patterns of ISR to best delineate the type of restenosis and help guide treatment. Intravascular imaging with either intravascular ultrasound or optical coherence tomography allows for real-time evaluation of ISR. We herein provide an illustrative review of the Waksman In-Stent Restenosis Classification.

Non-Invasive Treatment for Coronary In-Stent Restenosis via Wireless Revascularization With Nitinol Active Stent

This paper reports a novel shape memory alloy (SMA) nitinol type active stent for non-invasive restenosis treatment, which operates using a radiofrequency (RF) electro-thermo-mechanical actuation technique for wireless revascularization. The developed stent is equipped with a capacitive pressure sensor for in-artery blood pressure measurement and can provide multiple expansion to restore the blood pressure flow. The device design, working principle, fabrication, and characterization of the nitinol active stent are reported in this work. The wireless monitoring feature is achieved via peak shifting in the reflection coefficient of the S₁₁ parameter. The active stent with initial diameter and resonant frequency of 2 mm and 315 MHz, respectively, is expanded uniformly in stages up to 4.2 mm in diameter when excited with an RF power of ∼30 W for 320 s. The active stent is delivered and deployed ex vivo inside the left coronary artery of a cervine heart. The stented cervine heart before and after wireless actuation is inspected via penetration of X-rays. Endoscopic images reveal the expansion of the stent strut profile within the lumen of the stented artery. The active stent expands in stages up to 3.7 mm in diameter to scaffold the cervine coronary artery after excited with an RF power of 46.7 W. The achievable wireless revascularization capability eradicates the necessity of reintervention and repeat stenting procedure, whereas real-time wireless monitoring provides rapid indication of in-artery re-narrowing occurrence.

Intravascular Ultrasound in Chronic Total Occlusion Percutaneous Coronary Intervention: Solving Ambiguity and Improving Durability

Chronic total occlusions remain among the most technically challenging lesions to treat percutaneously. Limitations of 2-dimensional angiography may further hinder successful treatment of these lesions. Intrasvascular ultrasound has a key role in percutaneous recanalization for a chronic total occlusion by providing key lesion characteristics, facilitating guidewire crossing, elucidating the intraplaque or extralaque path of the guidewire, optimizing lesion preparation, guiding stenting and identifying suboptimal results. Live visualization of the guidewire during crossing may reduce extraplaque wire tracking. This review describes the practical uses of intravascular imaging for commonly encountered scenarios when treating chronic total occlusions.

Intravascular Imaging-Guided Percutaneous Coronary Intervention

Despite consistent clinical data supporting the use of intravascular imaging with percutaneous coronary intervention, utilization remains low. A practical and standardized approach to incorporating intravascular imaging with percutaneous coronary intervention may overcome the barriers to utilization. This review focuses on basic image interpretation with intravascular ultrasound and optical coherence tomography and proposes an algorithmic approach to stent sizing and optimization. Incorporation of this strategic method for percutaneous coronary intervention may aid in the greater adoption of intravascular imaging for percutaneous coronary intervention.

Clinical implication of neointimal burden in in-stent restenosis treated with drug-coated balloon

BACKGROUND

Although drug-coated balloon (DCB) angioplasty is a well-established drug-eluting stent (DES) in-stent restenosis (ISR) strategy, there are minimal data regarding the association of neointimal burden on optical coherence tomography (OCT) before and after DCB and adverse clinical events. This study aimed to investigate the clinical impact of neointimal burden measured with OCT in patients with DES ISR after DCB angioplasty.

METHODS

From 2010 through 2013, a total of 122 patients with 122 ISR lesions were treated with DCB, which was preceded and followed by OCT examination. Major adverse cardiac events (MACE, a composite occurrence of cardiovascular cardiac death, nonfatal myocardial infarction [MI], or target lesion revascularization [TLR]) were evaluated.

RESULTS

MACE occurred in 27 patients (4 nonfatal MIs and 23 TLRs) during the follow-up (median: 55.3 months, interquartile range 43.1-66.0). The mean lumen area was significantly smaller (3.21 ± 2.42 mm² vs. 4.80 ± 2.53 mm² , p = .005) and the mean percentage of neointimal volume derived by OCT was greater (49.3 ± 9.2% vs. 38.3 ± 17.5%, p = .006) in patients with MACE before DCB angioplasty. The pre-procedural mean percentage of neointimal volume (cut-off 50%, area under the receiver operating characteristic [ROC] curve = 0.644, 95% confidence interval [CI] = 0.531-0.758, p = .022) and post-procedural mean percentage of neointimal volume (cut-off 25%, area under ROC curve = 0.659, 95% CI = 0.546-0.773, p = .012) were identified as significant parameters to predict MACE.

CONCLUSION

The OCT-derived mean percentages of neointimal volume before and after DCB angioplasty can be important parameters for predicting future MACE in patients with DES ISR.