Bioresorbable Vascular Scaffolds-Dead End or Still a Rough Diamond?

Biodegradable Stents in the Treatment of Arterial Stenosis

Arterial diseases (ADs) are a significant health problem, with high mortality and morbidity rates. Endovascular interventions, such as balloon angioplasty (BA), bare-metal stents (BMSs), drug-eluting stents (DESs) and drug-coated balloons (DCBs), have made significant progress in their treatments. However, the issue has not been fully resolved, with restenosis remaining a major concern. In this context, bioresorbable vascular stents (BVSs) have emerged as a promising area of investigation. This manuscript includes articles that assess the use of BVSs. Studies have identified ongoing challenges, such as negative vascular remodeling and elastic recoil post-angioplasty, stent-related injury, and in-stent restenosis following BMS placement. While DESs have mitigated these issues to a considerable extent, their durable structures are unable to prevent late stent thrombosis and delay arterial recovery. BVSs, with their lower support strength and tendency towards thicker scaffolds, increase the risk of scaffold thrombosis. Despite inconsistent study results, the superiority of BVSs over DESs has not been demonstrated in randomized trials, and DES devices continue to be the preferred choice for most cases of arterial disease. Esprit BTK (Abbott Vascular) received approval from the US FDA for below-knee lesions in 2024, offering hope for the use of BVSs in other vascular conditions. Enhancing the design and thickness of BVS scaffolds may open up new possibilities. Large-scale and longer-term comparative studies are still required. This article aims to provide an overview of the use of biodegradable stents in the endovascular treatment of vascular stenosis.

Efficacy and safety of ticagrelor monotherapy following a brief DAPT vs. prolonged 12-month DAPT in ACS patients post-PCI: a meta-analysis of RCTs

BACKGROUND

As per current guidelines, acute coronary syndrome (ACS) patients who undergo percutaneous coronary intervention (PCI) should be started on dual antiplatelet therapy (DAPT) for a period of 12 months.

OBJECTIVE

To assess the efficacy and safety of brief DAPT (up to 3 months) succeeded by ticagrelor monotherapy compared with a 12-month DAPT in ACS patients following PCI.

METHODS

We systematically searched Cochrane, Embase, and PubMed to find relevant randomized clinical trials. Examined outcomes included the incidence of major adverse cerebrovascular and cardiovascular events (MACCE), bleeding events, and the composite incidence of net adverse clinical events (NACE).

RESULTS

Our primary analysis included 21,927 ACS patients from six RCTs. Our pooled results indicate that following PCI in individuals with ACS, brief DAPT followed by ticagrelor did not increase the risk of MACCE (OR 0.92, 95% CI 0.79-1.07) but significantly reduced the risk of minor or major bleeding (OR 0.52, 95% CI 0.44-0.62) and NACE (OR 0.71, 95% CI 0.59-0.86) compared with a long-term DAPT within a follow-up of 12 months.

CONCLUSION

Brief DAPT followed by ticagrelor monotherapy is superior to a 12-month DAPT in offering a net clinical advantage in ACS patients following PCI.

The unpredictable resorption of bioresorbable scaffolds-A tale of two ABSORBs

Bioresorbable stents represent a revolutionary treatment for coronary artery disease. Such a device offers the prospect for complete naturalization of artery lumen after strut resorption and restoration of vasomotion while curtailing the duration of dual anti-platelet therapy. The prototype bioresorbable scaffold (BRS-ABSORB GT1) demonstrated good feasibility and safety in the initial studies compared to metallic drug eluting stent but later fell out of favor due to multiple report of stent thrombosis and target lesion failure. Unpredictable resorption of struts turned out to be one of the "Achilles heel" of the BRS and stent strut were still visible in vessel on optical coherence tomography (OCT) at 3 years. We report a case of differential resorption of two ABSORB BRS implanted simultaneously in the same patient by the same operator. Follow up coronary angiogram revealed only minimal plaques on right coronary artery (RCA) and left anterior descending artery (LAD). The BRS were identified on cine-angiogram by their radio-opaque markers at both ends. The OCT run in LAD artery revealed "ghost remnants" of BRS struts in LAD, whereas the RCA BRS had completely healed with minimal "ghost" struts. The ghost remnants of BRS resembled the original "Check box" appearance on OCT during the index implantation.

In Vivo Efficacy of an Adhesive Bioresorbable Patch to Treat Aortic Dissections

Endovascular repair of aortic dissection still presents significant limitations. Preserving the mechanical and biological properties set by the aortic microstructure is critical to the success of implantable grafts. In this paper, we present the performance of an adhesive bioresorbable patch designed to cover the entry tear of aortic dissections. We demonstrate the power of using a biomimetic scaffold in a vascular environment.

48-Month Clinical Outcomes and Prognostic Factors in an All-Comers Population with Acute Coronary Syndrome and Chronic Coronary Syndrome Undergoing Percutaneous Coronary Intervention with a Sirolimus-Eluting Stent

We characterized the performance as well as safety of a second-generation thin-strut sirolimus-eluting stent with a biodegradable polymer, Alex Plus (Balton, Poland), deployed in the acute coronary syndrome (ACS) setting. We enrolled patients who were subjected to percutaneous coronary intervention (PCI) between July 2015 and March 2016 and took into consideration demographics, clinical and laboratory data, and clinical outcomes. We defined the primary endpoint as the 48-month rate of major cardiovascular adverse events (MACE), including cardiac death, myocardial infarction (MI), or target lesion revascularization (TLR). The secondary endpoints were all-cause death, cardiac death, MI, and TLR rates at 12-, 24-, 36-, and 48 months. We enrolled 232 patients in whom 282 stents were implanted, including 88 ACS and 144 chronic coronary syndrome (CCS) patients. The mean age of the ACS population was 67 ± 13 years old, and 32% of it consisted of females. Patients with ACS were characterized by lower rates of arterial hypertension (85.2% vs. 95.8%, p = 0.004), dyslipidemia (67% vs. 81.9%, p = 0.01), prior MI (34.1% vs. 57.6%, p < 0.001), and prior PCI (35.2% vs. 68.8%, p < 0.001). At 48 months, among the ACS patients, the rates of MACE, death, cardiac death, MI, and TLR were 23.9%, 11.4%, 7.9%, 9.1%, and 10.2%, respectively. No stent thrombosis cases were reported. Multivariable Cox regression revealed that the statistically significant MACE predictors were massive calcifications in coronary arteries (HR 9.0, 95% CI 1.75-46.3, p = 0.009), post-dilatation (HR 3.78, 95% CI 1.28-11.2, p = 0.016), prior CABG (HR 6.64, 95% CI 1.62-27.1, p = 0.008), vitamin K antagonist use (HR 5.99, 95% CI 1.29-27.8, p = 0.022), and rivaroxaban use (HR 51.7, 95% CI 4.48-596, p = 0.002). The study findings show that Alex Plus was effective and safe in a contemporary cohort of real-world ACS patients undergoing primary PCI. The outcomes were comparable between the ACS and chronic coronary syndrome patients, with a trend of lower TLR in ACS patients at 4 years.

Evolution of Coronary Stent Platforms: A Brief Overview of Currently Used Drug-Eluting Stents

Cardiovascular disease, including ischemic heart disease, is the leading cause of death worldwide, and percutaneous coronary interventions (PCIs) have been demonstrated to improve the prognosis of these patients on top of optimal medical therapy. PCIs have evolved from plain old balloon angioplasty to coronary stent implantation at the end of the last century. There has been a constant technical and scientific improvement in stent technology from bare metal stents to the era of drug-eluting stents (DESs) to overcome clinical challenges such as target lesion failure related to in-stent restenosis or stent thrombosis. A better understanding of the underlying mechanisms of these adverse events has led DESs to evolve from first-generation DESs to thinner and ultrathin third-generation DESs with improved polymer biocompatibility that seems to have reached a peak in efficiency. This review aims to provide a brief historical overview of the evolution of coronary DES platforms and an update on clinical studies and major characteristics of the most currently used DESs.

Thermo-Mechanical Characterization of 4D-Printed Biodegradable Shape-Memory Scaffolds Using Four-Axis 3D-Printing System

This study was conducted on different models of biodegradable SMP (shape-memory polymer) scaffolds. A comparison was conducted utilizing a basic FDM (fused deposition modeling)/MEX (material extrusion) printer with a standard printing technique and a novel, modified, four-axis printing method with a PLA (poly lactic acid) polymer as the printing material. This way of making the 4D-printed BVS (biodegradable vascular stent) made it possible to achieve high-quality surfaces due to the difference in printing directions and improved mechanical properties-tensile testing showed a doubling in the elongation at break when using the four-axis-printed specimen compared to the regular printing, of 8.15 mm and 3.92 mm, respectfully. Furthermore, the supports created using this method exhibited a significant level of shape recovery following thermomechanical programming. In order to test the shape-memory effect, after the thermomechanical programming, two approaches were applied: one approach was to heat up the specimen after unloading it inside temperature chamber, and the other was to heat it in a warm bath. Both approaches led to an average recovery of the original height of 99.7%, while the in-chamber recovery time was longer (120 s) than the warm-bath recovery (~3 s) due to the more direct specimen heating in the latter case. This shows that 4D printing using the newly proposed four-axis printing is an effective, promising technique that can be used in the future to make biodegradable structures from SMP.

Association of lactate detection with in-hospital mortality in critically ill patients with acute myocardial infarction: a retrospective cohort study

OBJECTIVES

To assess the associations of lactate level or lactate clearance at different time points with in-hospital mortality in critically ill patients with acute myocardial infarction (AMI).

DESIGN

A cohort study.

SETTING

The Medical Information Mart for Intensive Care III database.

PARTICIPANT

490 AMI patients.

INTERVENTION

None.

PRIMARY AND SECONDARY OUTCOME MEASURES

In-hospital mortality of patients.

RESULTS

In total, 120 (24.49%) patients died at the end of follow-up. After adjusting for confounders, increased risk of in-hospital mortality in patients with AMI was observed in those with high lactate level (24 hours) (HR=1.156, 95%CI: 1.002 to 1.333). Increased lactate clearance (24 hours) was correlated with a decreased risk of in-hospital mortality in patients with AMI (HR=0.995, 95% CI: 0.994 to 0.997). The area under the curves (AUCs) of lactate level (24 hours) and lactate clearance (24 hours) were 0.689 (95% CI: 0.655 to 0.723) and 0.672 (95% CI: 0.637 to 0.706), respectively. The AUC of lactate level (24 hours) and lactate clearance (24 hours) was higher than lactate level (baseline).

CONCLUSIONS

Increased lactate level (24 hours) was associated with an elevated risk of in-hospital mortality in patients with AMI and increased lactate clearance (24 hours) was correlated with a decreased risk of in-hospital mortality in patients with AMI despite the age and genders.

Preclinical Evaluation of an Everolimus-Eluting Bioresorbable Vascular Scaffold Via a Long-Term Rabbit Iliac Artery Model

BACKGROUND

Biodegradable poly (l-lactic acid) (PLLA), a bio safe polymer with a large elastic modulus, is widely used in biodegradable medical devices. However, because of its poor mechanical properties, a PLLA strut must be made twice as thick as a metal strut for adequate blood vessel support. Therefore, the mechanical properties of a drug-eluting metal-based stents (MBS) and a bioresorbable vascular scaffolds (BVS) were evaluated and their safety and efficacy were examined via a long-term rabbit iliac artery model.

METHODS

The surface morphologies of the MBSs and BVSs were investigated via optical and scanning electron microscopy. An everolimus-eluting (EE) BVS or an EE-MBS was implanted into rabbit iliac arteries at a 1.1:1 stent-to-artery ratio. Twelve months afterward, stented iliac arteries from each group were analyzed via X-ray angiography, optical coherence tomography (OCT), and histopathologic evaluation.

RESULTS

Surface morphology analysis of the EE coating on the MBS confirmed that it was uniform and very thin (4.7 μm). Comparison of the mechanical properties of the EE-MBS and EE-BVS showed that the latter outperformed the former in all aspects (radial force (2.75 vs. 0.162 N/mm), foreshortening (0.24% vs. 1.9%), flexibility (0.52 vs. 0.19 N), and recoil (3.2% vs. 6.3%). At all time points, the percent area restenosis was increased in the EE-BVS group compared to the EE-MBS group. The OCT and histopathological analyses indicate no significant changes in strut thickness.

CONCLUSION

BVSs with thinner struts and shorter resorption times should be developed. A comparable long-term safety/efficacy evaluation after complete absorption of BVSs should be conducted.

Evaluation of resistance to radial cyclic loads of poly(L-lactic acid) braided stents with different braiding angles

Poly(L-lactic acid) (PLLA) braided stents have superior biocompatibility and flexibility, substituting metal stents in peripheral blood vessels. However, the radial supporting capacity of PLLA braided stent should be improved to bear the dynamic load from the peripheral artery. This paper evaluated the radial support performance of PLLA braided stents with different braiding angles after the radial cyclic loads test. The results indicate that braiding angle of stents is an important parameter affecting its ability to resist radial cyclic loads. The stent with a smaller braiding angle has better initial radial support but insufficient durability, while the stent with a larger braiding angle could maintain adequate radial support and suitable ability to resist radial cyclic loads. The theoretical analysis, verified by observing the surface morphology of filament crossover points, found that filaments of the stents with smaller braiding angles have more significant axial displacement and axial rotation angle during radial compression, which made the friction phenomenon more intense and led to insufficient ability to resist radial cyclic loads. This study could provide a meaningful idea for preparing biodegradable braided stents with suitable ability to resist radial cyclic loads.

Different properties of poly(L-lactic acid) monofilaments and its corresponding braided springs after constrained and unconstrained annealing

Thermal annealing is widely applied to enhance the mechanical performance of PLLA monofilaments, which brings in a variety of expected strengths through different constrained methods. In this work, samples with constrained and unconstrained annealing process were both prepared and characterized, including mechanical performance, surface morphology, radial supporting performance and axial flexibility. Experimental results revealed that the monofilaments under constrained annealing showed higher elastic modulus with 6.4 GPa, which were higher than those without any constraint. While the maximal elongation at break with 51.11% were observed in unconstrained annealed monofilaments. Few changes were presented in the molecular weight between the two types of samples. Moreover, the springs under constrained annealing inhibited the most reliable radial supporting performance with higher radial compression force and chronic outward force, 0.665 N/mm and 0.14 N respectively. However, unconstrained annealing springs showed better flexibility with 0.178 N bending stiffness and 1.58 N maximum bending force. These results suggested that filaments and springs with various properties can be obtained under different annealing conditions.

Comparison of high-sensitivity C-reactive protein vs. C-reactive protein for diagnostic accuracy and prediction of mortality in patients with acute myocardial infarction

BACKGROUND

The role of chronic inflammation in the pathogenesis of atherosclerosis has been unequivocally proven. However, the prognostic impact of C-reactive protein, a marker of inflammatory response in patients with acute myocardial infarction has not been fully clarified. Furthermore, there is no direct comparison of the diagnostic accuracy of C-reactive protein and high sensitivity C-reactive protein in the acute myocardial infarction population.

METHODS

In this prospective observational cohort study, 344 patients with acute myocardial infarction were enrolled. All-cause mortality was a primary endpoint. Patients were followed prospectively for a median of six years.

RESULTS

The correlation between high sensitivity C-reactive protein and C-reactive protein (r = 0.99; P < 0.001) and the diagnostic accuracy (98.6%) was high. The ROC analysis revealed that C-reactive protein and high sensitivity C-reactive protein had a low AUC for prediction of mortality (C-reactive protein: 0.565, 95% CI [0.462-0.669], vs. high sensitivity C-reactive protein: 0.572, 95% CI [0.470-0.675]) or major adverse cardiac events (C-reactive protein: AUC 0.607, 95% CI [0.405-0.660], vs. high sensitivity C-reactive protein: AUC 0.526, 95% CI [0.398-0.653]) when assessed at time point of acute myocardial infarction. In contrast, longitudinal inflammatory risk assessment with serial C-reactive protein measurements in the stable phase of the disease revealed a 100% specificity, 100% negative predictive value, 32% sensitivity and 12% positive predictive value of C-reactive protein to predict long-term mortality. The Kaplan Meier analysis showed a significant survival benefit for patients at low residual inflammatory risk (P = 0.014).

CONCLUSION

C-reactive protein and high sensitivity C-reactive protein provide a similar diagnostic accuracy, highlighting that C-reactive protein might replace high sensitivity C-reactive protein in routine assessments. Furthermore, low inflammatory status during the stable phase after acute myocardial infarction predicts favourable six-year survival.

Efficacy and Safety of Ticagrelor Monotherapy in Patients Undergoing Percutaneous Coronary Intervention: A Meta-Analysis

Dual antiplatelet therapy (DAPT) and subsequent P2Y₁₂ inhibitor monotherapy, particularly ticagrelor, is an emerging treatment strategy in patients undergoing percutaneous coronary intervention (PCI). This meta‐analysis was designed to investigate whether short‐term DAPT followed by ticagrelor monotherapy is associated with a favorable outcome as compared with standard DAPT (1–3 months of DAPT was termed “short‐term” DAPT, 6–12 months DAPT was termed “standard” DAPT). The primary outcome was the composite of major adverse cardiovascular events (MACE) comprising myocardial infarction, stroke, and cardiovascular death. Secondary outcomes included all‐cause mortality and net adverse clinical events (NACE; myocardial infarction, stroke, all‐cause death, stent thrombosis, and major bleeding). The primary safety outcome was major bleeding. Three studies comprising 26,143 patients were included. The risk of MACE was similar between the two treatment groups (risk ratio (RR) 0.86, 95% confidence interval (CI), 0.72–1.02, P = 0.08, I² = 22%). Short‐term DAPT followed by ticagrelor monotherapy resulted in a 20% relative risk reduction of all‐cause mortality (RR 0.80, 95% CI, 0.65–0.98, P = 0.03, I² = 0%) and an 18% relative risk reduction of NACE (RR 0.82, 95% CI, 0.71–0.94, P = 0.005, I² = 33%) as compared with standard DAPT. Short‐term DAPT followed by ticagrelor monotherapy significantly decreased the risk of major bleeding (RR 0.67, 95% CI, 0.49–0.92, P = 0.01, I² = 65%). In patients with acute coronary syndrome, short‐term DAPT followed by ticagrelor monotherapy resulted in an unchanged ischemic risk but a significantly lower bleeding risk compared with standard DAPT. Short‐term DAPT followed by ticagrelor monotherapy compared with standard DAPT resulted in a favorable safety and efficacy profile. Direct comparisons of aspirin vs. ticagrelor monotherapy following PCI are needed.

Bioresorbable Scaffolds in Percutaneous Coronary Intervention: Facing Old Problems, Raising New Hopes

PURPOSE OF REVIEW

In this review, we discuss about the reasons behind the failure of the Absorb bioresorbable vascular scaffold (BVS) device and about the challenges the future holds for the next generation of the bioresorbable scaffold (BRS) technology.

RECENT FINDINGS

Absorb BVS was burdened by intrinsic structural limitations which resulted in augmented rates of device thrombosis and clinical adverse events compared to current-generation metallic stent. Nevertheless, new generation devices with novel design and materials are in development. Second generation BRS have enhanced mechanical strength, smaller footprints, less thrombogenicity and modified bioresorption. These features, paired with proper patient and lesion selection and optimal "user-friendly" implant techniques, could possibly overcome the previous BRS generation limitations, rekindling physicians, and industry interest on this promising technology.

Plasma Trimethylamine-N-Oxide Is an Independent Predictor of Long-Term Cardiovascular Mortality in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome

To investigate the association of liver metabolite trimethylamine N-oxide (TMAO) with cardiovascular disease (CV)-related and all-cause mortality in patients with acute coronary syndrome (ACS) who underwent percutaneous coronary intervention. Our prospective observational study enrolled 292 patients with ACS. Plasma concentrations of TMAO were measured during the hospitalization for ACS. Observation period lasted seven yr in median. Adjusted Cox-regression analysis was used for prediction of mortality. ROC curve analysis revealed that increasing concentrations of TMAO levels assessed at the time point of ACS significantly predicted the risk of CV mortality (c-index=0.78, p < 0.001). The cut-off value of >4 μmol/L, labeled as high TMAO level (23% of study population), provided the greatest sum of sensitivity (85%) and specificity (80%) for the prediction of CV mortality and was associated with a positive predictive value of 16% and a negative predictive value of 99%. A multivariate Cox regression model revealed that high TMAO level was a strong and independent predictor of CV death (HR = 11.62, 95% CI: 2.26-59.67; p = 0.003). High TMAO levels as compared with low TMAO levels were associated with the highest risk of CV death in a subpopulation of patients with diabetes mellitus (27.3 vs. 2.6%; p = 0.004). Although increasing TMAO levels were also significantly associated with all-cause mortality, their estimates for diagnostic accuracy were low. High TMAO level is a strong and independent predictor of long-term CV mortality among patients presenting with ACS.

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.

J, McAllister TN, L'Heureux N. Human textiles: A cell-synthesized yarn as a truly "bio" material for tissue engineering applications

In the field of tissue engineering, many groups have come to rely on the extracellular matrix produced by cells as the scaffold that provides structure and strength to the engineered tissue. We have previously shown that sheets of Cell-Assembled extracellular Matrix (CAM), which are entirely biological yet robust, can be mass-produced for clinical applications using normal, adult, human fibroblasts. In this article, we demonstrate that CAM yarns can be generated with a range of physical and mechanical properties. We show that this material can be used as a simple suture to close a wound or can be assembled into fully biological, human, tissue-engineered vascular grafts (TEVGs) that have high mechanical strength and are implantable. By combining this truly "bio" material with a textile-based assembly, this original tissue engineering approach is highly versatile and can produce a variety of strong human textiles that can be readily integrated in the body. STATEMENT OF SIGNIFICANCE: Yarn of synthetic biomaterials have been turned into textiles for decades because braiding, knitting and weaving machines can mass-produce medical devices with a wide range of shapes and mechanical properties. Here, we show that robust, completely biological, and human yarn can be produced by normal cells in vitro. This yarn can be used as a simple suture material or to produce the first human textiles. For example, we produced a woven tissue-engineered vascular grafts with burst pressure, suture retention strength and transmural permeability that surpassed clinical requirements. This novel strategy holds the promise of a next generation of medical textiles that will be mechanically strong without any foreign scaffolding, and will have the ability to truly integrate into the host's body.