Morphological, Functional, and Biological Vascular Healing Response 6 Months After Drug-Eluting Stent Implantation

Acute myocardial infarction caused by vasospasm of a jailed diagonal branch subsequent to stent implantation in the left anterior descending artery: a case report

Background

Coronary stents have been reported to cause endothelial dysfunction, potentially leading to spasm at the edges of the stent. However, the clinical significance of vascular spasm in stent-jailed side branches remains poorly understood.

Case summary

A 67-year-old woman was referred to our hospital for angina occurring both during exercise and at rest. An everolimus-eluting stent was implanted for a physiologically significant stenosis in the proximal left anterior descending artery, while an intermediate stenosis persisted in the jailed first diagonal branch. Although her exertional angina resolved, her rest symptoms worsened after percutaneous coronary intervention (PCI). She was admitted with acute myocardial infarction 1 month later. Urgent coronary angiography showed no stent failure, but an acetylcholine provocation test induced a spasm leading to total occlusion of the jailed diagonal branch. An additional stent was implanted in the diagonal branch due to a residual stenosis even after isosorbide dinitrate administration. After the second PCI, her chest pain completely resolved.

Discussion

This is the first documentation of aggregated coronary spasm observed at the ostium of stent-jailed side branch. Stent implantation may induce endothelial dysfunction and promote inflammation, leading to spasms particularly at stent edges. This phenomenon can extend to side branches jailed by the stent, and invasive intervention may be a viable therapeutic strategy for such cases.

Effects of TCFA on stent neointimal coverage at 9 months after EXCEL drug-eluting stent implantation assessed by OCT

BACKGROUND

The aim of this study was to investigate the effects of thin-cap fibroatheromas (TCFAs) on stent neointimal coverage at the 9‑month follow-up after EXCEL stent implantation assessed by optical coherence tomography (OCT).

METHODS

A total of 93 patients with non-ST elevation acute coronary syndrome (NSTEACS) who underwent EXCEL stent implantation were prospectively enrolled in the study and divided into a TCFA group (n = 47) and a non-TCFA group (n = 46) according to whether EXCEL stents covered the TCFAs. A TCFA was defined as a plaque with lipid content in more than one quadrant and fibrous cap thickness measuring less than 65 μm. The effect of TCFAs on stent neointimal coverage at the 9‑month follow-up after stent implantation was evaluated by OCT. The primary study endpoints were the incidence of neointimal uncoverage and stent malapposition.

RESULTS

At the 9‑month follow-up, the minimal lumen diameter of the TCFA group tended to be smaller (2.8 ± 0.8 vs. 2.1 ± 0.8, p = 0.08) and the diameter of stenosis in the TCFA group tended to be larger (15.1 ± 10.3% vs. 26.3 ± 15.1%, p = 0.08) than those in the non-TCFA group. The mean intimal thickness of the TCFA group was significantly lower than that of the non-TCFA group (67.2 ± 35.5 vs. 145.1 ± 48.7, p < 0.001). The uncovered struts (10.1 ± 9.7 vs. 4.8 ± 4.3, p = 0.05) and malapposed struts (2.1 ± 4.7 vs. 0.3 ± 0.5, p = 0.003) in the TCFA group were more significant than those in the non-TCFA group. Multivariate analysis showed that TCFAs and lesion types were independent predictors of incomplete neointimal coverage (p < 0.05), and lesion types were independent predictors of stent malapposition (p < 0.05).

CONCLUSION

In patients with NSTEACS, TCFAs delayed endothelium coverage at 9 months after stent implantation, and TCFAs were independent predictors of incomplete neointimal coverage of the stent.

Coronary Endothelium-Dependent Vasomotor Function After Drug-Eluting Stent and Bioresorbable Scaffold Implantation

Background Early generation drug-eluting stents (DESs) showed a high grade of coronary endothelial dysfunction that was attributed to lack of stent reendothelialization. Endothelium-dependent vasomotor response of current DESs and bioresorbable scaffolds (BRSs) remains unknown. This study sought to assess the device-related endothelial function of current devices and to correlate neointima healing with endothelial function. Methods and Results A total of 206 patients from 4 randomized trials treated with the durable-polymer everolimus-eluting Xience (n=44), bioresorbable-polymer sirolimus-eluting Orsiro (n=35), polymer-free biolimus-eluting Biofreedom (n=24), bioactive endothelial-progenitor cell-capturing sirolimus-eluting Combo DES (n=25), polymer-based everolimus-eluting Absorb (n=44), and Mg-based sirolimus-eluting Magmaris BRS (n=34) underwent endothelium-dependent vasomotor tests and optical coherence tomography imaging, as per protocol, at follow-up. Crude vasomotor responses of distal segments to low-dose acetylcholine (10^-6 mol/L) were different between groups: bioresorbablepolymer DEShad the worst (-8.4%±12.6%) and durable-polymer DES had the most physiologic (-0.4%±11.8%; P=0.014). High-dose acetylcholine (10^-4 mol/L) showed similar responses between groups (ranging from -10.8%±11.6% to -18.1%±15.4%; P=0.229). Device healing was different between devices. Uncovered struts ranged from 6.3%±7.1% (bioresorbable-polymer DES) to 2.5%±4.5% (bioactive DES; P=0.056). In multivariate models, endothelium-dependent vasomotor response was associated with age, bioresorbable-polymer DES, and angiographic lumen loss, but not with strut coverage nor plaque type. Endothelial dysfunction (defined as ≥4% vasoconstriction) was observed in 46.6% of patients with low-dose and 68.9% with high-dose acetylcholine, without differences between groups. Conclusions At follow-up, endothelial dysfunction was frequently observed in distal segments treated with current stents without remarkable differences between devices. Although neointima healing was different between devices, poor healing was not associated with endothelial dysfunction.

Coronary endothelial and microvascular function distal to polymer-free and endothelial cell-capturing drug-eluting stents. The randomized FUNCOMBO trial

INTRODUCTION AND OBJECTIVES

The vasomotor function of new-generation drug-eluting stents designed to enhance stent healing and reendothelialization is unknown. This study aimed to compare the endothelial function of the infarct-related artery (IRA) treated with bioactive circulating endothelial progenitor cell-capturing sirolimus-eluting stents (COMBO) vs polymer-free biolimus-eluting stents (BioFreedom) in ST-segment elevation myocardial infarction patients at 6 months. Secondary objectives were to compare the microcirculatory function of the IRA and stent healing at 6 months.

METHODS

Sixty patients were randomized to bioactive sirolimus-eluting stent vs polymer-free biolimus-eluting stents implantation. At 6 months, patients underwent coronary angiography with vasomotor, microcirculatory and optical coherence tomography examinations. Endothelial dysfunction of the distal coronary segment was defined as ≥ 4% vasoconstriction to intracoronary acetylcholine infusion.

RESULTS

Endothelial dysfunction was similarly observed between groups (64.0% vs 62.5%, respectively; P=.913). Mean lumen diameter decreased by 16.0 ±20.2% vs 16.1 ±21.6% during acetylcholine infusion (P=.983). Microcirculatory function was similar in the 2 groups: coronary flow reserve was 3.23 ±1.77 vs 3.23±1.62 (P=.992) and the index of microcirculatory resistance was 24.8±16.8 vs 21.3±12.0 (P=.440). Optical coherence tomography findings were similar: uncovered struts (2.3% vs 3.2%; P=.466), malapposed struts (0.1% vs 0.3%; P=.519) and major evaginations (7.1% vs 5.6%; P=.708) were observed in few cases.

CONCLUSIONS

Endothelial dysfunction of the IRA was frequent and was similarly observed with new-generation drug-eluting stents designed to enhance stent reendothelialization at 6 months. Endothelial dysfunction was observed despite almost preserved microcirculatory function and complete stent coverage. Larger and clinically powered studies are needed to assess the role of residual endothelial dysfunction in ST-segment elevation myocardial infarction patients. Registered in ClinicalTrials.gov: NCT04202172.

Comparison of neointimal coverage between ultrathin biodegradable polymer-coated sirolimus-eluting stents and durable polymer-coated everolimus-eluting stents: 6 months optical coherence tomography follow-up from the TAXCO study

Aim

The TAXCO study was designed to compare the degree of neointimal coverage and the prevalence of malapposition at 6 months subsequent to implantation of ultrathin biodegradable polymer‐coated sirolimus‐eluting stents (SES) and durable polymer‐coated everolimus‐eluting stents (EES) of thin strut thickness using optical coherence tomography (OCT).

Methods

The TAXCO study included a total of 42 patients who gave consent and underwent OCT examination between August 2017 and September 2017. Of 42, five patients' OCT examinations were of insufficient quality for quantitative analysis. Thus, the OCT analysis group consisted of 37 patients. Among them, 16 patients were treated with Xience (Abbott Vascular) and 21 with Tetriflex (Sahajanand Medical Technologies Pvt. Ltd., Surat, India), 6 (±1) months earlier at our institution. The OCT was performed using a C7 Dragonfly™ imaging catheter (St. Jude Medical Inc.). All OCT images were analyzed at an independent core laboratory (Cardiovascular Research Center, São Paulo, Brazil) by analysts who were blinded to patient and procedural information.

Results

A total of 763 crosssections (6,882 struts) were analyzed in Xience group, and 1,127 crosssections (9,968 struts) in Tetriflex group. At 6 months, on per‐lesion basis, no significant differences were observed between Xience group and Tetriflex group in mean percentage of uncovered struts (1.87 ± 3.86 vs. 2.42 ± 3.46, p = .137) and malapposed struts (0.05 ± 0.2 vs. 0.21 ± 0.69, p = .302). Strut‐level neointimal thickness also did not differ between Xience group and Tetriflex group (0.18 ± 0.12 vs. 0.14 ± 0.08 mm, p = .286).

Conclusion

This OCT study found no significant difference in strut coverage and neointimal thickness at 6 months after implantation of biodegradable polymer‐coated Tetriflex, when compared with durable polymer‐coated Xience.

Novel Zinc / Tungsten Carbide Nanocomposite as Bioabsorbable Implant

There is a lack of bioabsorbable materials with adequate mechanical strength suitable for implant applications that provide temporary support while tissue integrity is restored, especially for pediatric applications. Bioabsorbable metals have emerged as an attractive choice due to their combination of strength, ductility, and biocompatibility in vivo. Zinc has shown great promise as a bioabsorbable metal, but the weak mechanical properties of pure zinc limit its application as an implant material. This study investigates zinc-tungsten carbide (Zn-WC) nanocomposite as a novel material for bioabsorbable metallic implants. Ultrasound-assisted powder compaction was used to fabricate Zn-WC nanocomposites. This study includes the material characterization of microstructure, microhardness, and degradability. Results showed that tungsten carbide nanoparticles enhanced the mechanical properties of Zn, and maintained the favorable corrosion rate of pure Zn. These results encourage further investigation of Zn-WC nanocomposites for biomedical applications with the ultimate goal of creating safe and efficacious bioabsorbable metallic implants for many clinical applications.

The number of stents was an independent risk of stent restenosis in patients undergoing percutaneous coronary intervention

Percutaneous coronary intervention (PCI) is one of the most effective therapies for coronary artery disease, but stent restenosis remains an important clinical challenge. The studies about the independent effect of the number of stents on stent restenosis were limited.The purpose was to identify the independent effect of the number of stents on stent restenosis.A retrospective cohort study of data reuse.From July 2009 to August 2011, a total of 2338 cases met the inclusion and exclusion criteria.The univariate analysis showed that the number of stents was a risk of stent restenosis, the OR value was 1.30 (95% CI:1.15 to 1.47, P < .001). The multi-factor regression analysis also showed that the number of stents was an independent risk of stent restenosis, the adjusted OR value was 1.38 (95% CI: 1.15 to 1.66, P < .001).Compared with 1-2 stents, the adjusted OR values of 3-5 stents and more than 6 stents were respectively 2.20 (95% CI: 1.24 to 3.90, P = .007) and 5.33 (95% CI: 1.89 to 15.08, P = .002), and the trend adjusted OR values was 2.26 (95% CI: 1.43 to 3.59, P < .001).The subgroup analysis of multi-factor regression analysis showed that when patients with the following conditions: 50 < Age, female, non-DES or SES, the risk of stent restenosis increased obviously.The number of stents was an independent risk of stent restenosis in patients undergoing PCI, especially for patients with the following conditions: 2<the number of stents, 50 < age, female, Non-DES (Drug-eluting stents) or SES (sirolimus-eluting stent).

Intracoronary Optical Coherence Tomography 2018: Current Status and Future Directions

The advent of intravascular imaging has been a significant advancement in visualization of coronary arteries, particularly with optical coherence tomography (OCT) that allows for high-resolution imaging of intraluminal and transmural coronary structures. Accumulating data support a clinical role for OCT in a multitude of clinical scenarios, including assessing the natural history of atherosclerosis and modulating effects of therapies, mechanisms of acute coronary syndromes, mechanistic insights into the effects of novel interventional devices, and optimization of percutaneous coronary intervention. In this state-of-the-art review, we provide an overview of the published data on the clinical utility of OCT, highlighting the areas that need further investigation and the current barriers for further adoption of OCT in interventional cardiology practice.

Effects of Catheterization on Artery Function and Health: When Should Patients Start Exercising Following Their Coronary Intervention?

Coronary artery disease (CAD) is a leading cause of death worldwide, and percutaneous transluminal coronary angiography (PTCA) and/or percutaneous coronary intervention (PCI; angioplasty) are commonly used to diagnose and/or treat the obstructed coronaries. Exercise-based rehabilitation is recommended for all CAD patients; however, most guidelines do not specify when exercise training should commence following PTCA and/or PCI. Catheterization can result in arterial dysfunction and acute injury, and given the fact that exercise, particularly at higher intensities, is associated with elevated inflammatory and oxidative stress, endothelial dysfunction and a pro-thrombotic milieu, performing exercise post-PTCA/PCI may transiently elevate the risk of cardiac events. This review aims to summarize extant literature relating to the impacts of coronary interventions on arterial function, including the time-course of recovery and the potential deleterious and/or beneficial impacts of acute versus long-term exercise. The current literature suggests that arterial dysfunction induced by catheterization recovers 4-12 weeks following catheterization. This review proposes that a period of relative arterial vulnerability may exist and exercise during this period may contribute to elevated event susceptibility. We therefore suggest that CAD patients start an exercise training programme between 2 and 4 weeks post-PCI, recognizing that the literature suggest there is a 'grey area' for functional recovery between 2 and 12 weeks post-catheterization. The timing of exercise onset should take into consideration the individual characteristics of patients (age, severity of disease, comorbidities) and the intensity, frequency and duration of the exercise prescription.

Impact of low tissue backscattering by optical coherence tomography on endothelial function after drug-eluting stent implantation

This study evaluated the impact of optical coherence tomography (OCT)-derived low-backscattered tissue on mid-term coronary endothelial function after drug-eluting stent (DES) implantation. Although OCT enables detailed in vivo evaluation of neointimal tissue characterization after DES implantation, its association with physiological vascular healing response is unclear. Thirty-three stable angina pectoris patients underwent OCT examination and endothelial function testing with intracoronary infusion of incremental doses of acetylcholine 8-month after DES implantation in a single lesion of the left anterior descending artery. Neointimal tissue was classified into two patterns based on the predominant OCT light backscatter: high backscatter and low backscatter. Although the presence of uncovered or malapposed stent strut was not associated with the degree of vasoconstriction, the degree of vasoconstriction was significantly greater in the DES with low-backscattered neointima than in the DES without low-backscattered neointima (- 32.1 ± 25.7 vs. - 4.1 ± 20.1%, p = 0.003). Moreover, there was an inverse linear relationship between low backscatter tissue index and degree of vasoconstriction after acetylcholine infusion (r = 0.50 and p = 0.003). The endothelium-dependent vasomotor response after 8-month of DES was impaired in patients with low neointimal tissue backscatter on OCT imaging. OCT assessment of low-backscattered tissue may be used as surrogate markers for impairment of endothelial function after DES.

Inverse Relationship between Serum VEGF Levels and Late In-Stent Restenosis of Drug-Eluting Stents

Late in-stent restenosis (ISR) has raised concerns regarding the long-term efficacy of drug-eluting stents (DES). The role of vascular endothelial growth factor (VEGF) in the pathological process of ISR is controversial. This retrospective study aimed to investigate the relationship between serum VEGF levels and late ISR in patients with DES implantation. A total of 158 patients who underwent angiography follow-up beyond 1 year after intervention were included. The study population was classified into ISR and non-ISR groups. The ISR group was further divided according to follow-up duration and Mehran classification. VEGF levels were significantly lower in the ISR group than in the non-ISR group [96.34 (48.18, 174.14) versus 179.14 (93.59, 307.74) pg/mL, p < 0.0001]. Multivariate regression revealed that VEGF level, procedure age, and low-density lipoprotein cholesterol were independent risk factors for late ISR formation. Subgroup analysis demonstrated that VEGF levels were even lower in the very late (≥5 years) and diffuse ISR group (Mehran patterns II, III, and IV) than in the late ISR group (1–4 years) and the focal ISR group (Mehran pattern I), respectively. Furthermore, significant difference was found between diffuse and focal ISR groups. Serum VEGF levels were inversely associated with late ISR after DES implantation.