Vasomotor Response to Nitroglycerine Over 5 Years Follow-Up After Everolimus-Eluting Bioresorbable Scaffold Implantation

Long-term outcomes following bioresorbable vascular scaffolds

INTRODUCTION

The higher scaffold thrombosis rates observed with the first-generation bioresorbable scaffolds (BRSs) compared to conventional drug-eluting stents were likely due in part to bioresorbable polymers having insufficient radial strength, necessitating larger strut profiles. Meta-analysis of the long-term outcomes from the first-generation Absorb bioresorbable vascular scaffold (BVS) showed that this period of excess risk ended at 3 years. Therefore, current attention has been focused on improving early outcomes by increasing the scaffold's tensile strength and reducing strut thickness.

AREAS COVERED

This review summaries the lessons learned from the first-generation BRS. It updates the long-term clinical outcomes of trials evaluating the ABSORB BVS and metallic alloy-based BRS. In addition, it reviews the next-generation BRSs manufactured in Asia.

EXPERT OPINION

Critical areas to improve the performance and safety of biodegradable scaffolds include further development in material science, surface modification, delivery systems, and long-term follow-up studies.

Revolutionizing Cardiovascular Frontiers: A Dive Into Cutting-Edge Innovations in Coronary Stent Technology

Plain balloon angioplasty was the initial method used to enlarge the intracoronary lumen size. However, it was linked to acute coronary closure due to early vessel recoil. This led to the invention of coronary stents, which offer mechanical support to open and maintain the vascular lumen. Nevertheless, the metallic scaffold introduced other issues, such as thrombosis and restenosis caused by neointimal proliferation. To address these concerns, polymers were employed to cover the scaffold, acting as drug reservoirs and regulators for controlled drug release. The use of polymers prevents direct contact between blood and metallic scaffolds. Drugs within the stent were incorporated to inhibit proliferation and expedite endothelialization in the healing process. Despite these advancements, adverse effects still arise due to the inflammatory reaction caused by the polymer material. Consequently, resorbable polymers and scaffolds were later discovered, but they have limitations and are not universally applicable. Various scaffold designs, thicknesses, materials, polymer components, and drugs have their own advantages and complications. Each stent generation has been designed to address the shortcomings of the preceding generation, yet new challenges continue to emerge. Conflicting data regarding the long-term safety and efficacy of coronary stents, especially in the extended follow-up, further complicates the assessment.

Serial Baseline, 12-, 24-, and 60-Month Optical Coherence Tomography Evaluation of ST Segment Elevation Myocardial Infarction Patients Treated with Absorb Bioresorbable Vascular Scaffold

Data on long-term neointimal healing and neoatherosclerosis progression after primary percutaneous coronary intervention (PCI) with implantation of everolimus-eluting bioresorbable vascular scaffold (BVS) (ABSORB BVS 1.0, Abbott Vascular) are limited. The mechanisms underlying very late scaffold failure remain to be further elucidated. This study sought to assess healing pattern and presence of neoatherosclerosis. This was a single-center, prospective, longitudinal study with serial optical coherence tomography (OCT) assessment at baseline, 12, 24 and 60 months after PCI performed in 12 patients presenting with ST-segment elevation myocardial infarction (STEMI). The median follow-up was 59 months. The diameter stenosis increased from 7.11 ± 4.99% at 1-year to 21.00 ± 11.31% at 5 years, (p = 0.03), whereas minimum lumen diameter remained stable throughout the follow-up period, as assessed by angiography. Minimum and mean lumen area declined over the 5-year follow-up by 1.00 ± 1.57 mm2 and 1.75 ± 0.87 mm2, respectively; a significant decrease in minimum and mean lumen area in the first two years, was followed by stable luminal dimensions between 2 and 5 years of follow-up. The lumen eccentricity (0.85 ± 0.03) and asymmetry (0.43 ± 0.10) indexes showed no change over 60-month follow-up. The incidence of atherosclerosis was high both in the in-scaffold (IS) and out-scaffold (OS) regions consisting of calcifications (IS = 100%, OS = 92%, p = 0.99), macrophages (IS = 92% and OS = 67%, p = 0.31), neovascularization (IS = 75%, OS = 50%, p = 0.40). In conclusion, serial OCT imaging up to 5 years after implantation of BVS in STEMI indicated complete scaffold resorption, stable lumen area following period of neointima growth in the first two years after PCI and high incidence of neoatherosclerosis.

Inflammation as a determinant of healing response after coronary stent implantation

Cardiovascular disease remains the leading cause of death and morbidity worldwide. Inflammation plays an important role in the development of atherosclerosis and is associated with adverse clinical outcomes in patients after percutaneous coronary interventions. Data on stent elements that lead to excessive inflammatory response, proper identification of high-risk patients, prevention and treatment targeting residual inflammatory risk are limited. This review aims to present the role of inflammation in the context of evolving stent technologies and appraise the potential imaging modalities in detection of inflammatory response and anti-inflammatory therapies.

Outcomes after complete dissolution of everolimus-eluting bioresorbable scaffolds implanted during routine practice

INTRODUCTION AND OBJECTIVES

Long-term outcomes of unselected patients treated with bioresorbable vascular scaffold (BVS) implantation are lacking, especially for the period after complete dissolution of the BVS. This study sought to evaluate 5-year outcomes in patients treated with BVS in routine practice.

METHODS

Consecutive patients who underwent implantation of everolimus-eluting BVS during routine clinical practice at 2 high-volume centres in Germany were studied. The patients were followed-up for up to 5 years. The primary endpoints of interest were the composite of death, myocardial infarction and target lesion revascularization, as well as definite scaffold thrombosis.

RESULTS

A total of 419 patients (mean age 66.6 ± 10.9 years; 31.5% had diabetes) were included, of whom 38.9% presented with an acute coronary syndrome. Of the 527 lesions treated, 49.0% were classified as complex and 13.1% were bifurcation lesions. At 5 years, the composite clinical endpoint occurred in 33.1% of patients and definite scaffold thrombosis occurred in 4.7%. Most definite scaffold thrombosis occurred within 2 years after BVS implantation.

CONCLUSIONS

In patients treated with BVS implantation in routine clinical practice the rates of adverse clinical events at 5 years were high, including a considerable incidence of scaffold thrombosis.

Bioresorbable scaffold implantation in STEMI patients: 5 years imaging subanalysis of PRAGUE-19 study

Background

Bioresorbable scaffold (BRS) Absorb™ clinical use has been stopped due to higher rate of device thrombosis. Scaffold struts persist longer than 2 years in the vessel wall. Second generation devices are being developed. This study evaluates long-term invasive imaging in STEMI patients.

Methods

PRAGUE-19 study is an academic study enrolling consecutive STEMI patients with intention to implant Absorb™ BRS. A total of 83 STEMI patients between December 2012 and March 2014 fulfilled entry criteria. Coronary angiography and optical coherence tomography at 5 year follow-up was performed in 25 patients.

Results

Primary combined clinical endpoint (death, myocardial infarction or target vessel revascularization) occurred in 12.6% during the five-year follow-up with overall mortality 6.3%. Definite scaffold thrombosis occurred in 2 patients in the early phase after BRS implantation. Quantitative coronary angiography after 5 years demonstrated low late lumen loss of 0.11 ± 0.35 mm with binary restenosis rate of 0%. Optical coherence tomography demonstrated complete resorption of scaffold struts and mean lumen diameter of 3.25 ± 0.30 and 3.22 ± 0.49 (P = 0.73) at baseline and after 5 years, respectively. Three patients developed small coronary artery aneurysm in the treated segment.

Conclusion

Invasive imaging results 5 years after BRS implantation in STEMI showed complete resorption of scaffold struts and stable lumen vessel diameter.

Trial registration ISRCTN43696201 (retrospectivelly registred, June 7th, 2019). https://www.isrctn.com/ISRCTN43696201.

Fully bioresorbable vascular scaffolds: lessons learned and future directions

Fully bioresorbable scaffolds (BRS) were designed to overcome the limitations of metallic drug-eluting stents, which permanently cage the vessel wall, thereby preventing normal coronary vasomotion, preclude bypass grafting and can provoke long-term foreign-body responses. Although multiple scaffolds have been or are in development, the Absorb Bioresorbable Vascular Scaffold (BVS; Abbott Vascular) was the first FDA-approved device and was widely expected to fulfil the dream of interventional cardiologists of a transient scaffold that would disappear 'when the job was done' and would not hamper further treatment options. Although early, small studies and even large, randomized trials showed beneficial outcomes up to 1 year of follow-up, longer-term results have been disappointing, with increased rates of device thrombosis and target-lesion revascularization. The Absorb BVS device was withdrawn from the market because of low demand. In this Review, we summarize the preclinical and clinical data available for BRS to understand how the vascular biological reactions to these devices differ from biological reactions to metallic drug-eluting stents and how these responses translate into clinical outcomes. We also discuss next-generation BRS and outline modifications that are needed to improve the long-term outcomes with these devices so that they eventually become a viable option for patients with symptomatic obstructive coronary artery disease.

Neoatherosclerosis - Long-Term Assessment of Bioresorbable Vascular Scaffold

Although metallic stents improved the safety and efficacy of percutaneous coronary intervention (PCI), even the latest generation of drug-eluting stents (DES) is still limited by several factors. The limitations of DES are mainly related to the permanent metallic caging in vessel, chronic inflammatory response to the polymer and adverse effects of antiproliferative drug on endothelial tissue, leading to impaired physiological vasomotor response and late stent-related adverse events such as stent thrombosis and neoatherosclerosis. Bioresorbable vascular scaffold (Absorb BVS; Abbott Vascular) was designed to overcome these drawbacks of DES by disappearing from the vessel wall. Absorb BVS, however, was withdrawn from the world market because of increased incidence of scaffold thrombosis compared with DES. Importantly, only very limited long-term post-BVS implantation data are available, especially with regard to neoatherosclerosis, which can lead to very late adverse events even after resorption of the scaffold. Therefore, the goal of this review was to highlight the mid to long term clinical outcomes published to date, and to describe the features of the intimal healing process and neoatherosclerosis in the 5 years following Absorb BVS implantation, mainly based on our previous study. This may provide important information on the pathophysiology of the scaffolded vessel for clinicians, and promote identification of future bioresorbable materials for PCI that will minimize the stimulus for neoatherosclerosis.

Neoatherosclerosis 5 Years After Bioresorbable Vascular Scaffold Implantation

BACKGROUND

Data regarding neoatherosclerosis after everolimus-eluting bioresorbable vascular scaffold (BVS) (ABSORB BVS Rev. 1.1, Abbott Vascular, Santa Clara, California) implantation are limited.

OBJECTIVES

This study investigated the findings of neoatherosclerosis at 5 years after BVS 1.1 implantation by using multi-imaging modalities, including optical coherence tomography (OCT).

METHODS

Patients included in the ABSORB EXTEND (ABSORB EXTEND Clinical Investigation) trial at Shonan Kamakura General Hospital underwent OCT at baseline after the index procedure and at 1 and 5 years. Intimal plaque distributions in the in-scaffold and out-scaffold segments were analyzed.

RESULTS

Twenty patients (22 lesions) with stable angina pectoris were enrolled. The median follow-up duration was 67 months (interquartile range: 65 to 69 months), and the mean age was 69 ± 8 years. Patients with diabetes mellitus (25%) were included. Based on the baseline angiogram, 10 (46%) lesions were type B2/C lesions. At 1 and 5 years of follow-up, significant differences in the prevalence of in-scaffold lipid-laden neointima (17% vs. 61%; p = 0.04), calcification (28% vs. 94%; p < 0.01), neovascularization (6% vs. 78%; p < 0.01), and thin-cap fibroatheroma (0% vs. 22%; p = 0.02) were found. In the out-scaffold segments, no significant difference in the plaque prevalence between 1 and 5 years was noted.

CONCLUSIONS

The occurrence and progression of in-scaffold neoatherosclerosis with luminal narrowing was observed at 5 years after BVS 1.1 implantation. The small size of the current study warrants confirmation in larger study. (ABSORB EXTEND Clinical Investigation [ABSORB EXTEND]; NCT01023789).

Three-year clinical outcomes of patients treated with everolimus-eluting bioresorbable vascular scaffolds: Final results of the ABSORB EXTEND trial

BACKGROUND

There is still limited data on the very long term clinical outcomes after ABSORB BRS in daily practice. We sought to evaluate the 3 year-performance of the Absorb bioresorbable vascular scaffolds for the treatment of low/moderate complexity patients enrolled in the ABSORB EXTEND trial.

METHODS

ABSORB EXTEND is a prospective, single-arm, open-label clinical study in which 812 patients were enrolled at 56 sites. This study allowed the treatment of lesions ≤28 mm in length and reference vessel diameter of 2.0-3.8 mm (as assessed by on-line QCA). To determine the independent predictors of MACE, a multivariable logistic regression model was built using a stepwise (forward/backward) procedure.

RESULTS

Average population age was 61 years and 26.5% had diabetes. Most patients had single target lesion (92.4%). Adequate scaffold deployment (PSP) was achieved in 14.2% of the cases. At three years, the composite endpoints of MACE and ischemia-driven target vessel failure were 9.2% and 10.6%, respectively. The cumulative rate of ARC definite/probable thrombosis was 2.2%, with 1.2% of the cases occurring after the 1st year. Independent predictors of MACE were hypertension and the need for "bail out" stent.

CONCLUSION

At three-year follow-up, the use of ABSORB in low/moderate complex PCI was associated with low and acceptable rates of major adverse clinical events, despite the infrequent use of the recommended contemporary scaffold deployment technique. However, scaffold thrombosis rate was higher than reported with current generation of metallic DES. The study is registered on clinicaltrials.gov (unique identifier NCT01023789).

Intracoronary focal nitroglycerin injection through drilled balloon is very effective in the resolution of coronary spasm versus into proximal coronary artery: A prospective randomized comparison study

BACKGROUND

In this study, we aimed to compare the effectiveness and safety of NTG administration via catheter and local NTG infusion through a perforated balloon in order to prevent coronary spasm from developing during percutaneous intervention.

METHOD

The study began with 1:1 randomization into two groups of a total of 1688 patients scheduled for PCT. A total of 91 patients in the proximal group who developed lesions received 500 mcg NTG through a catheter, while 85 patients in the local group with lesions developed during the procedure received 500 mcg local NTG through a perforated balloon. After excluding patients who did not develop lesions during the procedure, and those without any change in the lesion with NTG application, the study was completed with 74 patients in the local group, and 70 patients in the proximal group.

RESULTS

Both groups were similar in terms of basic characteristics. Incidences of procedure-related hypotension (10% vs 52%, P < 0.001) and tachycardia (20% vs 57%, P < 0.001) were significantly lower in the local NTG group. Success in addressing spasm was significantly higher in the local NTG than in the proximal NTG group (91.66 ± 14.09% vs 75.99 ± 16.86%, P < 0.001).

DISCUSSION

Intracoronary injection with a perforated balloon, a simple technique introduced worldwide with our publication, can be used for administration of local NTG. Using this method, NTG can be better delivered with the perforated balloon to the vascular epithelium because of lower output, higher eruption rate, and perpendicularity to the endothelium. In this application, the balloon can better deliver drugs to the desired area via back-and-forth movements using a 0.014 guidewire.

CONCLUSION

The local administration of NTG to a spasming area through a perforated balloon is more effective and safer than the proximal administration of NTG.

Restenosis, Stent Thrombosis, and Bleeding Complications: Navigating Between Scylla and Charybdis

The field of interventional cardiology has significantly evolved over 40 years by overcoming several challenges. The introduction of first-generation drug-eluting stents significantly reduced the rates of restenosis, but at the expense of an increase of late stent thrombosis. Prolonged antithrombotic therapy reduced rates of stent thrombosis, but at the cost of increased bleeding. Although the advent of second-generation drug-eluting stents subsequently reduced the incidence of late stent thrombosis, its permanent nature prevents full recovery of vascular structure and function with accordant risk of very late stent failure. In the present era of interventional cardiology, the tradeoff between stent thrombosis, restenosis, and bleeding presents as a particularly complex challenge. In this review, the authors highlight major contributors of late/very late stent thrombosis while targeting stent restenosis, and they discuss evolutionary advances in stent technology and antiplatelet therapy, to further improve upon the care of patients with coronary artery disease.

The effect of bioresorbable vascular scaffold implantation on distal coronary endothelial function in dyslipidemic swine with and without diabetes

BACKGROUND

We studied the effect of bioresorbable vascular scaffold (BVS) implantation on distal coronary endothelial function, in swine on a high fat diet without (HFD) or with diabetes (DM+HFD).

METHODS

Five DM+HFD and five HFD swine underwent BVS implantation on top of coronary plaques, and were studied six months later. Conduit artery segments >5mm proximal and distal to the scaffold and corresponding segments of non-scaffolded coronary arteries, and segments of small arteries within the flow-territory of scaffolded and non-scaffolded arteries were harvested for in vitro vasoreactivity studies.

RESULTS

Conduit segments proximal and distal of the BVS edges showed reduced endothelium-dependent vasodilation as compared to control vessels (p≤0.01), with distal segments being most prominently affected(p≤0.01). Endothelial dysfunction was only observed in DM±HFD swine and was principally due to a loss of NO. Endothelium-independent vasodilation and vasoconstriction were unaffected. Surprisingly, segments from the microcirculation distal to the BVS showed enhanced endothelium-dependent vasodilation (p<0.01), whereas endothelium-independent vasodilation and vasoconstriction were unaltered. This enhanced vasorelaxation was only observed in DM+HFD swine, and did not appear to be either NO- or EDHF-mediated.

CONCLUSIONS

Six months of BVS implantation in DM+HFD swine causes NO-mediated endothelial dysfunction in nearby coronary segments, which is accompanied by a, possibly compensatory, increase in endothelial function of the distal microcirculation. Endothelial dysfunction extending into coronary conduit segments beyond the implantation-site, is in agreement with recent reports expressing concern for late scaffold thrombosis and of early BVS failure in diabetic patients.