Contemporary Management of Stent Failure: Part One

Stent failure: the diagnosis and management of intracoronary stent restenosis

INTRODUCTION

Despite advances in stent technology for percutaneous coronary intervention (PCI) in the treatment of coronary disease, these procedures can be complicated by stent failure manifesting as intracoronary stent restenosis (ISR). Even with advances of stent technology and medical therapy this complication is reported to affect around 10% of all percutaneous coronary intervention (PCI) procedures. Depending on stent type (drug-eluting versus bare metal), ISR have subtle differences in mechanism and timing and offer different challenges in diagnosing the etiology and subsequent treatment options.

AREAS COVERED

This review will be visiting the definition, pathophysiology and risk factors of ISR.

EXPERT OPINION

The evidence behind management options has been illustrated with the aid of real life clinical cases and summarized in a proposed management algorithm.

Relationship Between Attenuated Plaque Identified by Intravascular Ultrasound and Thrombus Formation After Excimer Laser Coronary Angioplasty

BACKGROUND

Excimer laser coronary angioplasty (ELCA) has been reported to be a safe and effective atherectomy device in percutaneous coronary intervention (PCI). However, thrombotic complications after ELCA have been occasionally observed. In this study, we evaluated the impact of attenuated plaque on thrombus formation and transient no-reflow after ELCA.

METHODS

This study enrolled 58 lesions in 56 patients who underwent PCI with ELCA. It was a retrospective observational study at a single center. All lesions were imaged by intravascular ultrasound (IVUS) before and immediately after ELCA. On the plaque with ultrasound attenuation, attenuation angle per millimeter and attenuation length were measured. ELCA-induced thrombus was detected by IVUS, and transient no-reflow after ELCA was recorded.

RESULTS

Thrombus was detected in 14 lesions (30 %), and transient no-reflow occurred in 3 lesions (5 %). Lesions with thrombus had a higher mean attenuation angle (median [interquartile range] 142° [112°-152°] vs. 64° [0°-115°]; p = 0.001), maximum attenuation angle (209° [174°-262°] vs. 86° [0°-173°]; p < 0.001), and longer attenuation length (12 mm [8 mm-17 mm] vs. 2 mm [0 mm-5 mm]; p < 0.001). Lesions with thrombus leading to transient no-reflow had a longer lipid length and a significantly higher troponin I level after PCI.

CONCLUSIONS

IVUS-identified attenuated plaque was strongly correlated with ELCA-induced thrombus. Furthermore, attenuation length may predict transient no-reflow.

Treatment of In-Stent Restenosis Using a Dedicated Super High-Pressure Balloon

BACKGROUND

Treatment of in-stent restenosis (ISR) is challenging and treatment failure rate remains high. Correction of stent under-expansion and neointimal compression using the twin-layer OPN™ highly non-compliant balloon (NCB) at high pressure (>30 atm) may lead to increased luminal gain and thus better clinical outcomes. We evaluated periprocedural safety and clinical long-term outcomes after ISR treatment using the OPN™ NCB in a real-world population.

METHODS

From an ongoing registry, consecutive ISR patients treated with the OPN™ NCB at a tertiary cardiology center in Switzerland were analyzed. We evaluated procedural efficacy, periprocedural complications, target lesion/vessel failure (TLF/TVF), and major adverse cardiovascular events (MACE).

RESULTS

Totally, 208 ISR lesions were treated in 188 patients (mean age 68 ± 13 years, 78 % males). Most lesions were moderately to heavily calcified (89 %), the majority (70.2 %) had complex lesion characteristics (AHA Type B2/C lesions) and 50.5 % were non-focal ISR lesions. After ISR treatment using high pressure pre- and post-dilatation (mean pressure 33 ± 6 atm) with the OPN™ NCB device, the rate of major complications was low (0.96 % coronary perforation, 4 % major dissections, 1.9 % no-reflow and 0.5 % acute vessel closure). At 1-year follow-up, MACE occurred in 19.7 %; 15.4 % patients had TVF; MI and stent thrombosis was found in 5.9 % and 2.1 % of all patients, respectively; and 5 patients died.

CONCLUSIONS

For ISR treatment, using the super non-compliant OPN™ balloon at very high pressures is safe. Moreover, its use might lead to a low rate of TLF/TVF during long-term follow-up, but this requires further evaluation in dedicated comparative trials.

Predicting Cardiovascular Stent Complications Using Self-Reporting Biosensors for Noninvasive Detection of Disease

Self-reporting implantable medical devices are the future of cardiovascular healthcare. Cardiovascular complications such as blocked arteries that lead to the majority of heart attacks and strokes are frequently treated with inert metal stents that reopen affected vessels. Stents frequently re-block after deployment due to a wound response called in-stent restenosis (ISR). Herein, an implantable miniaturized sensor and telemetry system are developed that can detect this process, discern the different cell types associated with ISR, distinguish sub plaque components as demonstrated with ex vivo samples, and differentiate blood from blood clot, all on a silicon substrate making it suitable for integration onto a vascular stent. This work shows that microfabricated sensors can provide clinically relevant information in settings closer to physiological conditions than previous work with cultured cells.

The Mechanisms of Restenosis and Relevance to Next Generation Stent Design

Stents are lifesaving mechanical devices that re-establish essential blood flow to the coronary circulation after significant vessel occlusion due to coronary vessel disease or thrombolytic blockade. Improvements in stent surface engineering over the last 20 years have seen significant reductions in complications arising due to restenosis and thrombosis. However, under certain conditions such as diabetes mellitus (DM), the incidence of stent-mediated complications remains 2–4-fold higher than seen in non-diabetic patients. The stents with the largest market share are designed to target the mechanisms behind neointimal hyperplasia (NIH) through anti-proliferative drugs that prevent the formation of a neointima by halting the cell cycle of vascular smooth muscle cells (VSMCs). Thrombosis is treated through dual anti-platelet therapy (DAPT), which is the continual use of aspirin and a P2Y₁₂ inhibitor for 6–12 months. While the most common stents currently in use are reasonably effective at treating these complications, there is still significant room for improvement. Recently, inflammation and redox stress have been identified as major contributing factors that increase the risk of stent-related complications following percutaneous coronary intervention (PCI). The aim of this review is to examine the mechanisms behind inflammation and redox stress through the lens of PCI and its complications and to establish whether tailored targeting of these key mechanistic pathways offers improved outcomes for patients, particularly those where stent placement remains vulnerable to complications. In summary, our review highlights the most recent and promising research being undertaken in understanding the mechanisms of redox biology and inflammation in the context of stent design. We emphasize the benefits of a targeted mechanistic approach to decrease all-cause mortality, even in patients with diabetes.

In Stent Neo-Atherosclerosis: Pathophysiology, Clinical Implications, Prevention, and Therapeutic Approaches

Despite the dramatic improvements of revascularization therapies occurring in the past decades, a relevant percentage of patients treated with percutaneous coronary intervention (PCI) still develops stent failure due to neo-atherosclerosis (NA). This histopathological phenomenon following stent implantation represents the substrate for late in-stent restenosis (ISR) and late stent thrombosis (ST), with a significant impact on patient’s long-term clinical outcomes. This appears even more remarkable in the setting of drug-eluting stent implantation, where the substantial delay in vascular healing because of the released anti-proliferative agents might increase the occurrence of this complication. Since the underlying pathophysiological mechanisms of NA diverge from native atherosclerosis and early ISR, intra-coronary imaging techniques are crucial for its early detection, providing a proper in vivo assessment of both neo-intimal plaque composition and peri-strut structures. Furthermore, different strategies for NA prevention and treatment have been proposed, including tailored pharmacological therapies as well as specific invasive tools. Considering the increasing population undergoing PCI with drug-eluting stents (DES), this review aims to provide an updated overview of the most recent evidence regarding NA, discussing pathophysiology, contemporary intravascular imaging techniques, and well-established and experimental invasive and pharmacological treatment strategies.

Comparison of visibility of in-stent restenosis between conventional- and ultra-high spatial resolution computed tomography: coronary arterial phantom study

PURPOSE

The purposes of this experimental study were to compare the quantitative and qualitative visibility of in-stent restenosis between conventional-resolution CT (CRCT) and ultra-high-resolution CT (U-HRCT) and to investigate the effects of the image reconstruction techniques on the visualization of in-stent restenosis.

MATERIALS AND METHODS

A vessel tube with non-calcified plaque in a 3.0-mm stent was scanned by using CRCT and U-HRCT at 4 stent directions (0, 30, 60, and 90 degrees) to the through-plane direction. Hybrid iterative reconstruction (HIR); model-based iterative reconstruction (MBIR); deep-learning-based reconstruction (DLR) were used as reconstruction methods. The lumen size was assessed using the full width at half maximum method, and image quality was visually evaluated using 4-point scale.

RESULTS

U-HRCT had the significantly wider lumen sizes and narrower stent strut thickness than CRCT in three types of the reconstruction methods (P < 0.01). The lumen sizes for U-HRCT with 90 degrees were narrower than those with the other angle directions regardless of the reconstruction methods. Visual score was significantly higher for U-HRCT than CRCT (3.2 ± 0.7 vs 2.0 ± 0.4, P < 0.001).

CONCLUSIONS

U-HRCT quantitatively and qualitatively provided better visualization of in-stent restenosis compared to CRCT. Image quality of U-HRCT may be affected by stent angle.

Intrastent haematoma after treatment with a drug-eluting balloon for in-stent restenosis: a case report

Background

Intrastent haematoma after dilatation of in-stent restenosis (ISR) is rarely reported and the optimal treatment for this condition remains unclear.

Case summary

We present the case of an 87-year-old man with in-stent subtotal occlusion of left circumflex. He experienced chest pain after drug-eluting balloon was released in the stent. Intravascular ultrasound revealed intrastent haematoma, which was not relieved with a cutting balloon but completely sealed by an Endeavor Resolute stent.

Discussion

Intrastent haematoma after dilatation of ISR is rare. Reimplantation of stent seems the best method to solve this problem. Intravascular ultrasound imaging may provide insight into the cause of ISR and guide the treatment.

Excimer Laser Coronary Angioplasty in Coronary Lesions: Use and Safety From the NCDR/CATH PCI Registry

[Figure: see text].

Clinical characteristics of early and late drug-eluting stent in-stent restenosis and mid-term prognosis after repeated percutaneous coronary intervention

Background:

The mechanism and characteristics of early and late drug-eluting stent in-stent restenosis (DES-ISR) have not been fully clarified. Whether there are different outcomes among those patients being irrespective of their repeated treatments remain a knowledge gap.

Methods:

A total of 250 patients who underwent initial stent implantation in our hospital, and then were readmitted to receive treatment for the reason of recurrent significant DES-ISR in 2016 were involved. The patients were categorized as early ISR (<12 months; E-ISR; n = 32) and late ISR (≥12 months; L-ISR; n = 218). Associations between patient characteristics and clinical performance, as well as clinical outcomes after a repeated percutaneous coronary intervention (PCI) were evaluated. Primary composite endpoint of major adverse cardiac events (MACEs) included cardiac death, non-fatal myocardial infarction (MI), or target lesion revascularization (TLR).

Results:

Most baseline characteristics are similar in both groups, except for the period of ISR, initial pre-procedure thrombolysis in myocardial infarction, and some serum biochemical indicators. The incidence of MACE (37.5% vs. 5.5%; P < 0.001) and TLR (37.5% vs. 5.0%; P < 0.001) is higher in the E-ISR group. After multivariate analysis, E-ISR (odds ratio [OR], 13.267; [95% CI 4.984–35.311]; P < 0.001) and left ventricular systolic dysfunction (odds ratio [OR], 6.317; [95% CI 1.145–34.843]; P = 0.034) are the independent predictors for MACE among DES-ISR patients in the mid-term follow-up of 12 months.

Conclusions:

Early ISR and left ventricular systolic dysfunction are associated with MACE during the mid-term follow-up period for DES-ISR patients. The results may benefit the risk stratification and secondary prevention for DES-ISR patients in clinical practice.

Procedural and 1-year clinical outcomes of orbital atherectomy for treatment of coronary in-stent restenosis: A single-center, retrospective study

OBJECTIVES

We evaluated the procedural and 1-year clinical outcomes of orbital atherectomy (OA) for treatment of coronary in-stent restenosis (ISR).

BACKGROUND

The optimal treatment for ISR remains uncertain. While rotational and laser atherectomy have been used as neointimal debulking techniques for ISR, there have been few reports on OA for ISR.

METHODS

This is a retrospective observational study of consecutive patients who underwent percutaneous coronary intervention (PCI) for ISR with OA in Mount Sinai catheterization laboratory between November 2013 and January 2018. Procedural success was defined as angiographic success without in-hospital major adverse cardiac events (MACE; the composite of all-cause death, myocardial infarction [MI], or target vessel revascularization). Clinical outcomes were assessed at 1 month and 12 months postprocedure.

RESULTS

A total of 87 patients were included in the study. All 87 patients were treated with OA, after which 49 (56.3%) patients also received new drug-eluting stents. Angiographic success was achieved in 87 (100%) patients and procedural success was achieved in 79 (90.8%) patients. In-hospital MACE occurred in 8 (9.2%) patients, all due to periprocedural non-Q-wave MI. Acute lumen gain was 1.19 ± 0.57 mm after OA plus balloon angioplasty and 1.75 ± 0.50 mm after stent placement. MACE within 1 year occurred in 17 (19.5%) patients.

CONCLUSIONS

OA for ISR was performed with favorable procedural and 1-year clinical outcomes. Randomized trials are warranted to determine whether OA improves the poor prognosis of patients with ISR treated without debulking.

Management of dual traumatic arterial-venous fistula from a single shotgun injury: a case report and literature review

Background

Traumatic arteriovenous fistula (TAVF) is an uncommon vascular entity that arises in various locations, often from penetrating injuries, with a wide spectrum of signs and symptoms. This case report highlights the importance of suspecting multiple TAVFs after a single gunshot wound, especially if it involves pellets. It also sheds light on adapting treatment, whether endovascular or open repair, to the location and characteristics of each fistula.

Case presentation

A 35-year-old male, with history of shotgun wound 5 months earlier, presented to our clinic with right lower extremity (RLE) edema and pain. Arterial duplex scan and subsequent angiogram showed two TAVFs at the popliteal and posterior tibial (PT) arteries, both of which could not be exactly localized with a computed tomography angiography (CTA) due to artifacts. The fistula connecting the posterior tibial artery (PTA) and vein was repaired endovascularly using a covered-stent, while the fistula between the popliteal artery and vein was repaired surgically. Postoperative follow-up at 3 months showed no arteriovenous fistula (AVF), patent vessels and distal stent stenosis at the PTA.

Conclusions

Patients who sustain gunshot injuries with shrapnel or pellets and develop TAVF consequentially need to be followed up with the possibility of multiple AVFs in mind. Arterial duplex scan is highly sensitive to detect those AVFs, yet angiography remains gold standard, particularly with extensive metal artefacts. Endovascular repair, when feasible, should be considered first, unless the patient is unstable or has anatomical constraints that increase the risk of complications. Lastly, surgeons should be weary of deep venous thrombosis (DVT), the Branham effect and arterial aneurysmal dilation postoperatively.

Self-perception of overweight and obesity: A review of mental and physical health outcomes

The obesity crisis is one of the largest public health challenges of the 21st century. Population‐level adiposity has increased dramatically in recent times, and people not recognizing that they have overweight or obesity is now common. It has been widely assumed that not recognizing oneself as having overweight is detrimental to weight management and long‐term health. Here, diverse research is reviewed that converges on the counterintuitive conclusion that not recognizing oneself as having overweight is actually associated with more favourable physical and mental health outcomes than recognizing oneself as having overweight. Drawing on existing models in social psychology and weight stigma research, an explanatory model of the health effects of self‐perception of overweight is outlined. This model proposes that self‐perception of overweight triggers social rejection concerns and the internalization of weight stigma, which in turn induce psychological distress and negatively impact health‐promoting lifestyle behaviours. How self‐perception of overweight may in part explain progression from overweight to obesity, and the public health implications of self‐perception of overweight and obesity are also discussed.

Zn2+-dependent suppression of vascular smooth muscle intimal hyperplasia from biodegradable zinc implants

Biodegradable arterial implants based on zinc have been found to suppress neointimal hyperplasia, suggesting that biodegradable materials containing zinc may be used to construct vascular implants with a reduced rate of restenosis. However, the molecular mechanism has remained unclear. In this report, we show that zinc-containing materials can be used to prevent neointimal formation when implanted into the rat aorta. Indeed, neointimal cells were significantly more TUNEL positive and alpha-actin negative at the interface of biodegradable zinc vs. biostable platinum implants, in association with greater caspase-3 activity. Although zinc stimulated extensive neointimal smooth muscle cell (SMC) death, macrophage and proinflammatory markers CD68 and iNOS were not increased in neointimal tissue relative to biostable platinum control implants. Using arterial explants, ionic zinc was confirmed to promote SMC apoptosis by activating the caspase apoptotic signaling pathway. These observations suggest that zinc-containing materials can be used to construct vascular implants such as stents with reduced neointimal hyperplasia.

Towards revealing key factors in mechanical instability of bioabsorbable Zn-based alloys for intended vascular stenting

Zn-based alloys are recognized as promising bioabsorbable materials for cardiovascular stents, due to their biocompatibility and favorable degradability as compared to Mg. However, both low strength and intrinsic mechanical instability arising from a strong strain rate sensitivity and strain softening behavior make development of Zn alloys challenging for stent applications. In this study, we developed binary Zn-4.0Ag and ternary Zn-4.0Ag-xMn (where x = 0.2-0.6wt%) alloys. An experimental methodology was designed by cold working followed by a thermal treatment on extruded alloys, through which the effects of the grain size and precipitates could be thoroughly investigated. Microstructural observations revealed a significant grain refinement during wire drawing, leading to an ultrafine-grained (UFG) structure with a size of 700 nm and 200 nm for the Zn-4.0Ag and Zn-4.0Ag-0.6Mn, respectively. Mn showed a powerful grain refining effect, as it promoted the dynamic recrystallization. Furthermore, cold working resulted in dynamic precipitation of AgZn3 particles, distributing throughout the Zn matrix. Such precipitates triggered mechanical degradation through an activation of Zn/AgZn3 boundary sliding, reducing the tensile strength by 74% and 57% for Zn-4.0Ag and Zn-4.0Ag-0.6Mn, respectively. The observed precipitation softening caused a strong strain rate sensitivity in cold drawn alloys. Short-time annealing significantly mitigated the mechanical instability by reducing the AgZn3 fraction. The ternary alloy wire showed superior microstructural stability relative to its Mn-free counterpart due to the pinning effect of Mn-rich particles on the grain boundaries. Eventually, a shift of the corrosion regime from localized to more uniform was observed after the heat treatment, mainly due to the dissolution of AgZn3 precipitates. STATEMENT OF SIGNIFICANCE: Owing to its promising biodegradability, zinc has been recognized as a potential biodegradable material for stenting applications. However, Zn's poor strength alongside intrinsic mechanical instability have propelled researchers to search for Zn alloys with improved mechanical properties. Although extensive researches have been conducted to satisfy the mentioned concerns, no Zn-based alloys with stabilized mechanical properties have yet been reported. In this work, the mechanical properties and stability of the Zn-Ag-based alloys were systematically evaluated as a function of microstructural features. We found that the microstructure design in Zn alloys can be used to find an effective strategy to not only improve the strength and suppress the mechanical instability but also to minimize any damage by augmenting the corrosion uniformity.