Specific binding to intracellular proteins determines arterial transport properties for rapamycin and paclitaxel

Efficacy of paclitaxel-coated versus uncoated balloon angioplasty for revascularization of coronary in-stent restenosis: a meta-analysis and metaregression

BACKGROUND

Treatment of in-stent restenosis (ISR) accounts for 10% of percutaneous coronary interventions in the USA. Paclitaxel-coated balloons (PCBs) are an alternative to uncoated balloons (UCBs) for ISR.

METHODS

We systematically searched PubMed, Scopus, and Cochrane Central for studies comparing PCB with UCB in treating ISR. Outcomes included late lumen loss, binary restenosis, target lesion revascularization (TLR), and major adverse cardiovascular events (MACE).

RESULTS

Eight trials including 1410 patients [PCB in 865 (61%), follow-up 6 months to 10 years) were identified. Angiographic outcomes of late lumen loss [mean difference: -0.50 mm; 95% confidence interval (CI): -0.66 to -0.33; P < 0.01] and binary restenosis [relative risk (RR): 0.22; 95% CI: 0.13-0.40; P < 0.01] at 6-8 months were lower with PCB. TLR at 6 months (RR: 0.16; 95% CI: 0.06-0.40; P < 0.001) and 1 year (RR: 0.45; 95% CI: 0.31-0.66; P < 0.001), MACE at 6 months (RR: 0.25; 95% CI: 0.16-0.38; P < 0.001), MACE at 3-5 years (RR: 0.54; 95% CI: 0.37-0.80; P = 0.002), and TLR at 3-5 years (RR: 0.51; 95% CI: 0.29-0.90; P = 0.021) were lower with PCB. Meta-regression revealed that ISR lesions in the left anterior descending artery were associated with lower rates of binary restenosis while the opposite was observed for left circumflex lesions.

CONCLUSION

Revascularization of coronary ISR with PCB is associated with reduced late lumen loss, binary restenosis, TLR, CCE, and MACE. PCB may be a preferred strategy for coronary ISR.

Transport across the thoracic aortic wall: implications for aneurysm pathobiology, diagnosis, and treatment

Thoracic aortic aneurysms (TAAs) are a dilation of the aorta that may fatally dissect or rupture. The current clinical management for TAA is continuous monitoring and surgical replacement once the aortic diameter reaches a specified size or rate of growth. Although operative intervention is often successful in preventing fatal outcomes, not all patients will reach surgical criteria before an aortic event, and the surgery carries significant risk with a potential requirement for reoperation. There is a need for patient-specific diagnostic tools and/or novel therapeutics to treat TAA. In this review, we discuss fluid and solute transport through the aortic wall (transmural aortic transport), its potential contributions to TAA progression, and possible applications for diagnosis and treatment. We first discuss the structural organization of the aortic wall with a focus on cellular and extracellular matrix (ECM) changes associated with TAA that may alter transmural transport. We then focus on aortic transmural transport processes defined with biphasic and multiphasic theory. Biphasic theory describes fluid interactions with a porous solid (i.e., the aortic wall), whereas multiphasic theory describes fluid and solute(s) interactions with a porous solid. We summarize experimental and computational methods to quantify transport through the aortic wall. Finally, we discuss how transmural transport may be used to diagnose, monitor, or treat TAA. Further understanding of transmural transport may lead to new insights into TAA pathobiology and future clinical solutions.

A systematic review and meta-analysis of the use of drug-coated balloon angioplasty for treatment of both de novo and in-stent coronary chronic total occlusions

BACKGROUND

Modern contemporary percutaneous coronary intervention (PCI) techniques with drug-eluting stents (DES) have high procedural success rates in chronic total occlusion (CTO) but with a high prevalence of repeat revascularization. The use of drug-coated balloons (DCBs) in CTO is an alternative treatment strategy. The evidence for DCBs in CTO is, therefore, of interest, and we provide a structured and comprehensive review of the evidence available in terms of the use of DCBs in CTO, including de novo and in-stent (IS) CTO lesions.

OBJECTIVES

We conducted a systematic review and meta-analysis on the use of DCBs in the management of coronary CTO.

METHODS

Electronic databases (PubMed, Embase and Ovid) were systematically searched from inception to April 2024 for DCB CTO studies. A meta-analysis was undertaken using a random-effects inverse-variance method due to heterogeneity. The primary outcome is target lesion revascularization (TLR). Secondary outcomes are major adverse cardiac events (MACE) as a composite of target lesion revascularization (TLR), cardiac death (CD), and any myocardial infarction (MI) including procedural and non-procedural MI, target vessel revascularization (TVR), angiographic outcomes such as late lumen loss (LLL), binary restenosis, and reocclusion.

RESULTS

A total of 10 studies consisting of 1,695 patients were systematically reviewed. This showed that late luminal changes in terms of lumen gain and minimal lumen loss were consistently seen in CTO cohorts 7-12 months after DCB treatment. Five studies were included for meta-analysis with 1,474 patients. There were no significant differences in TLR between treatment strategies such as DCB, DES, and hybrid (DES + DCB) in both de novo and IS-CTO populations as follows: DCB vs DES [OR, 0.71; 95% CI 0.49-1.02], DCB vs DES in IS-CTO [OR, 0.78; 95% CI 0.45-1.34], DCB vs Hybrid [OR, 0.96; 95% CI 0.39-1.43], and hybrid vs DES [OR, 0.76; 95% CI 0.15-3.84]. Similar findings were seen with the MACE outcome. A sensitivity analysis showed no difference between the above-mentioned groups in terms of MI, CD, and TVR.

CONCLUSION

The limited initial evidence on DCB in coronary CTO-PCI suggests a safe and effective alternative treatment strategy and suggests RCTs are, therefore, required.

Small-Diameter Stents in Cardiovascular Applications

Small-diameter stents play a crucial role in treating congenital heart diseases and variety of vascular conditions that have application from paediatrics to geriatric conditions, and a comprehensive review in this direction is lacking. This review explores historical development, design innovations, material compositions and mechanistic insights into functions of small-diameter stents, with a specific emphasis on biodegradable options. The necessity for stents that can adapt to growth of paediatric patients is discussed, highlighting the transition from durable polymers to bioresorbable materials such as polylactic acid (PLA) and magnesium alloys. While acknowledging the advancements made in reducing complications like restenosis and thrombosis, the review addresses the challenges that persist, including the need for improved biocompatibility and minimization of late adverse cardiac events associated with certain stent technologies. A detailed examination of various stent generations emphasizes the importance of drug release kinetics, structural integrity and potential for personalized interventions based on patient-specific factors. The exploration of novel therapeutic compounds, including nanoparticles and interfering RNA, illustrates the ongoing research aimed at enhancing stent efficacy. Ultimately, the review seeks to provide a comprehensive understanding of current landscape while identifying the gaps that future research must address to develop the ideal stent for diverse patient populations.

A multiphasic model for determination of mouse ascending thoracic aorta mass transport properties with and without aneurysm

Thoracic aortic aneurysms (TAAs) are associated with aortic wall remodeling that affects transmural transport or the movement of fluid and solute across the wall. In previous work, we used a Fbln4E57K/E57K (MU) mouse model to investigate transmural transport changes as a function of aneurysm severity. We compared wild-type (WT), MU with no aneurysm (MU-NA), MU with aneurysm (MU-A), and MU with an additional genetic mutation that led to increased aneurysm penetrance (MU-XA). We found that all aneurysmal aortas (MU-A and MU-XA) had lower fluid flux compared to WT. Non-aneurysmal aortas (MU-NA) had higher 4 kDa FITC-dextran solute flux than WT, but aneurysmal MU-A and MU-XA aortas had solute fluxes similar to WT. Our experimental results could not isolate competing factors, such as changes in aortic geometry and solid material properties among these mouse models, to determine how intrinsic transport properties change with aneurysm severity. The objective of this study is to use biphasic and multiphasic models to identify changes in transport material properties. Our biphasic model indicates that hydraulic permeability is significantly decreased in the severe aneurysm model (MU-XA) compared to non-aneurysmal aortas (MU-NA). Our multiphasic model shows that effective solute diffusivity is increased in MU-NA aortas compared to all others. Our findings reveal changes in intrinsic transport properties that depend on aneurysm severity and are important for understanding the movement of fluids and solutes that may play a role in the diagnosis, progression, or treatment of TAA.

Endovascular tools for vascular access stenosis: Flow-chart proposal

Stenosis represents the most relevant arteriovenous fistula (AVF) pathology and can affects the entire conduit forming the fistula, from afferent artery to central venous vessels. Correction of vascular access stenosis significantly affects the survival and quality of life for end stage renal disease patients (ESRD) dependent on hemodialysis. Guidelines consider the procedure of percutaneous transluminal angioplasty (PTA) relevant for the primary treatment of these lesions with excellent results in restoring AVF immediately at the end of the procedure. From first AVF angioplasty in 1981 to now, wide scientific innovation has led to development of new devices, composed by different materials and technologies, specific for the site and the type of stenosis to be treated, able to manage resistant stenotic lesion and to reduce stenosis recurrences. International guidelines do not clearly specify all treatment possibilities in the individual case. In this review the authors want to provide specific information on most used devices for stenosis treatment based on literature evidence, showing when and where to use the various tools available with flow-chart treatment proposal.

Polymer-interface-tissue model to estimate leachable release from medical devices

The ability to predict clinically relevant exposure to potentially hazardous compounds that can leach from polymeric components can help reduce testing needed to evaluate the biocompatibility of medical devices. In this manuscript, we compare two physics-based exposure models: 1) a simple, one-component model that assumes the only barrier to leaching is the migration of the compound through the polymer matrix and 2) a more clinically relevant, two-component model that also considers partitioning across the polymer-tissue interface and migration in the tissue away from the interface. Using data from the literature, the variation of the model parameters with key material properties were established, enabling the models to be applied to a wide range of combinations of leachable compound, polymer matrix and tissue type. Exposure predictions based on the models suggest that the models are indistinguishable over much of the range of clinically relevant scenarios. However, for systems with low partitioning and/or slow tissue diffusion, the two-component model predicted up to three orders of magnitude less mass release over the same time period. Thus, despite the added complexity, in some scenarios it can be beneficial to use the two-component model to provide more clinically relevant estimates of exposure to leachable substances from implanted devices.

Safety and efficacy of drug-eluting stents versus heparin-bonded stents in treatment of femoropopliteal peripheral artery disease: study protocol for a multicentre, prospective randomised controlled trial in China (ELITE trial)

INTRODUCTION

Endovascular therapy has emerged as a prominent strategy for managing femoropopliteal peripheral artery disease, offering acceptable safety and efficacy compared with open surgical bypass. Both paclitaxel-eluting stents and heparin-bonded covered stents have exhibited enhanced clinical outcomes compared with bare metal stents. However, there is currently a lack of level I evidence comparing the safety and efficacy of paclitaxel-eluting stents and heparin-bonded covered stents. Therefore, the primary objective of this study is to systematically evaluate the efficacy and safety outcomes of these two types of stents.

METHODS AND ANALYSIS

The ELITE trial is a prospective, multicentre, parallel, randomised controlled trial. A total of 450 patients will be recruited. The primary endpoints of the study include primary patency at 1 year post-index procedure.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained from the Ethics Committee of West China Hospital of Sichuan University (approval number: 2023-1186). The results will be submitted to a major clinical journal for peer review and publication.

TRIAL REGISTRATION

ELITE trial was registered on 27 September 2023 in the Chinese Clinical Trials Registry (ChiCTR2300076236).

Predictors of target lesion failure after percutaneous coronary intervention with a drug-coated balloon for de novo lesions

BACKGROUND

There are limited data about determinant factors of target lesion failure (TLF) in lesions after percutaneous coronary intervention (PCI) using a drug-coated balloon (DCB) for de novo coronary artery lesions, including optical coherence tomography (OCT) findings.

AIMS

The present study aims to investigate the associated factors of TLF in de novo coronary artery lesions with DCB treatment.

METHODS

We retrospectively enrolled 328 de novo coronary artery lesions in 328 patients who had undergone PCI with a DCB. All lesions had been treated without a stent, and both pre- and post-PCI OCT had been carried out. Patients were divided into two groups, with or without TLF, which was defined as a composite of culprit lesion-related cardiac death, myocardial infarction, and target lesion revascularisation, and the associated factors of TLF were assessed.

RESULTS

At the median follow-up period of 460 days, TLF events occurred in 31 patients (9.5%) and were associated with patients requiring haemodialysis (HD; 29.0% vs 10.8%), with a severely calcified lesion (median maximum calcium arc 215° vs 104°), and with the absence of OCT medial dissection (16.1% vs 60.9%) as opposed to those without TLF events. In Cox multivariable logistic regression analysis, HD (hazard ratio [HR]: 2.26, 95% confidence interval [CI]: 1.00-5.11; p=0.049), maximum calcium arc (per 90°, HR: 1.34, 95% CI: 1.05-1.72; p=0.02), and the absence of post-PCI medial dissection on OCT (HR: 8.24, 95% CI: 3.15-21.6; p<0.001) were independently associated with TLF.

CONCLUSIONS

In de novo coronary artery lesions that received DCB treatment, factors associated with TLF were being on HD, the presence of a severely calcified lesion, and the absence of post-PCI medial dissection.

Efficacy and safety of drug-coated balloons in chronic total coronary occlusion recanalization: a systematic review and meta-analysis

BACKGROUND

With advancements in chronic total coronary occlusion (CTO) recanalization techniques and concepts, the success rate of recanalization has been steadily increasing. However, the current data are too limited to draw any reliable conclusions about the efficacy and safety of drug-coated balloons (DCBs) in CTO percutaneous coronary intervention (PCI). Herein, we conducted a meta-analysis to confirm the efficacy of DCB in CTO PCI.

METHODS

We systematically searched PubMed, Web of Science and Embase from inception to July 25, 2023. The primary outcome was major advent cardiovascular events (MACE), including cardiac death, nonfatal myocardial infarction (MI), target lesion revascularization (TLR), and target vessel revascularization (TVR). The follow-up angiographic endpoints were late lumen enlargement (LLE), reocclusion and restenosis.

RESULTS

Five studies with a total of 511 patients were included in the meta-analysis. Across studies, patients were predominantly male (72.9-85.7%) and over fifty years old. The summary estimate rate of MACE was 13.0% (95% CI 10.1%-15.9%, I2 = 0%, p = 0.428). The summary estimate rates of cardiac death and MI were 2.2% (95% CI 0.7%-3.7%, I2 = 0%, p = 0.873) and 1.2% (95% CI -0.2-2.6%, I2 = 13.7%, p = 0.314), respectively. Finally, the pooled incidences of TLR and TVR were 10.1% (95% CI 5.7%-14.5%, I2 = 51.7%, p = 0.082) and 7.1% (95% CI 3.0%-11.2%, I2 = 57.6%, p = 0.070), respectively. Finally, the summary estimate rates of LLE, reocclusion and restenosis were 59.4% (95% CI 53.5-65.3%, I2 = 0%, p = 0.742), 3.3% (95% CI 1.1-5.4%, I2 = 0%, p = 0.865) and 17.5% (95% CI 12.9-22.0%, I2 = 0%, p = 0.623), respectively.

CONCLUSION

Accordingly, DCB has the potential to be used as a treatment for CTO in suitable patients.

Serial angiography and angioscopy of late lumen enlargement after drug-coated balloon for dysfunctional arteriovenous fistula

The use of a drug-coated balloon (DCB) to treat dysfunctional arteriovenous fistula (AVF) has shown promising results. After percutaneous coronary intervention with DCB, late lumen enlargement (LLE) often develops in the early follow-up phase, but questions regarding the natural history of changes in lesions after DCB angioplasty have not been clearly elucidated. Here, we reported on a patient in whom angiography and angioscopy were performed immediately and 4 months after DCB angioplasty to treat cephalic vein stenosis of the dysfunctional AVF. Immediately after DCB application, angiography showed good dilatation and blood flow and mild vascular dissection that did not affect blood flow. Angioscopy showed that although the balloon had damaged the intima and the paclitaxel particles had adhered to the vessel wall. Four months after DCB treatment, follow-up angiography and angioscopy were performed. Angiography showed LLE in the cephalic vein of the AVF that had been treated by DCB angioplasty. Angioscopy showed that the intima of the vessel had almost completely healed, and the paclitaxel particles had disappeared. LLE might occur when DCB is used for AVF.

Efficacy and Safety of Dual Paclitaxel and Sirolimus Nanoparticle-Coated Balloon

We evaluated a novel dual active pharmaceutical ingredient (API) drug-coated balloon (DCB), which consists of a coating of nanoparticles encapsulating low-dose paclitaxel (PTX) in combination with sirolimus in a synergistic ratio. Compared to the PTX DCB, the dual API DCB demonstrated similar inhibition of cell proliferation in vitro but at a significantly lower total drug dose (over 13 times lower than sirolimus nanoparticles). Animal experiments demonstrated that the dual API DCB is more effective in inhibiting intimal cell proliferation with insignificant downstream embolic effects and myocardial damage compared to the PTX DCB. These findings indicate that dual API DCBs have a high potential to demonstrate improved clinical outcomes and a greater safety profile than the PTX DCBs.

Drug-Coated Balloons in the Management of Coronary Artery Disease

Drug-coated balloons (DCBs) are specialized coronary devices comprised of a semicompliant balloon catheter with an engineered coating that allows the delivery of antiproliferative agents locally to the vessel wall during percutaneous coronary intervention. Although DCBs were initially developed more than a decade ago, their potential in coronary interventions has recently sparked renewed interest, especially in the United States. Originally designed to overcome the limitations of conventional balloon angioplasty and stenting, they aim to match or even improve upon the outcomes of drug-eluting stents without leaving a permanent implant. Presently, in-stent restenosis is the condition with the most robust evidence supporting the use of DCBs. DCBs provide improved long-term vessel patency compared with conventional balloon angioplasty and may be comparable to drug-eluting stents without the need for an additional stent layer, supporting their use as a first-line therapy for in-stent restenosis. Beyond the treatment of in-stent restenosis, DCBs provide an additional tool for de novo lesions for a strategy that avoids a permanent metal scaffold, which may be especially useful for the management of technically challenging anatomies such as small vessels and bifurcations. DCBs might also be advantageous for patients with high bleeding risk due to the decreased necessity for extended antiplatelet therapy, and in patients with diabetes and patients with diffuse disease to minimize long-stented segments. Further studies are crucial to confirm these broader applications for DCBs and to further validate safety and efficacy.

Endovascular Drug Delivery

Drug-eluting stents (DES) and balloons revolutionize atherosclerosis treatment by targeting hyperplastic tissue responses through effective local drug delivery strategies. This review examines approved and emerging endovascular devices, discussing drug release mechanisms and their impacts on arterial drug distribution. It emphasizes the crucial role of drug delivery in modern cardiovascular care and highlights how device technologies influence vascular behavior based on lesion morphology. The future holds promise for lesion-specific treatments, particularly in the superficial femoral artery, with recent CE-marked devices showing encouraging results. Exciting strategies and new patents focus on local drug delivery to prevent restenosis, shaping the future of interventional outcomes. In summary, as we navigate the ever-evolving landscape of cardiovascular intervention, it becomes increasingly evident that the future lies in tailoring treatments to the specific characteristics of each lesion. By leveraging cutting-edge technologies and harnessing the potential of localized drug delivery, we stand poised to usher in a new era of precision medicine in vascular intervention.

Different drugs in drug-eluting stents for peripheral artery disease: a systematic evaluation and Bayesian meta-analysis

Drug-eluting stents (DESs) have become the first-line treatment for symptomatic peripheral arterial disease (PAD). Currently, there are many types of DESs on the market. The same type of DESs has different concentrations, and various drugs in them show uneven efficacy. The selection of DESs remains controversial. This study was aimed at comparing the long-term real-world outcomes of different DESs in the treatment of peripheral arterial occlusive disease (PAOD). The databases including Cochrane Library, Embase, and PubMed were searched with a time frame until March 25, 2023. The primary patency (PP) and target lesion revascularization (TLR) at 6 months were used as the primary endpoints. A total of 32 studies (5467 patients) were eligible. At the six-month follow-up, DES-Evero 1 ug/mm2 ranked first in terms of PP, with a significant difference from BMSs (RR [95% CI] = 1.6). DES-Siro 0.9 ug/mm2, DES-Siro 1.4 ug/mm2, DES-Siro 1.95 ug/mm2, DES-PTX 0.167 ug/mm2, DES-PTX 1 ug/mm2 and covered stents (CSs) showed significantly better PPs than BMSs. In terms of TLR, DES-Siro 0.9 ug/mm2 (0.31) ranked first, and DES-Evero 1 ug/mm2 ranked last. Among the treatment modalities for PAD, different DESs showed overall encouraging results in improving PP and TLR compared with BMSs. DES-Evero 1 ug/mm2 showed the best PP, but it had the highest reintervention rate at 6 months. Sirolimus-eluting stents were not always more effective with higher concentrations of sirolimus. Among various DESs, sirolimus-eluting stents and everolimus-eluting stents were superior to paclitaxel-eluting stents.

Single-Cell RNA Sequencing Reveals That Adaptation of Human Aortic Endothelial Cells to Antiproliferative Therapies Is Modulated by Flow-Induced Shear Stress

BACKGROUND

Endothelial cells (ECs) are capable of quickly responding in a coordinated manner to a wide array of stresses to maintain vascular homeostasis. Loss of EC cellular adaptation may be a potential marker for cardiovascular disease and a predictor of poor response to endovascular pharmacological interventions such as drug-eluting stents. Here, we report single-cell transcriptional profiling of ECs exposed to multiple stimulus classes to evaluate EC adaptation.

METHODS

Human aortic ECs were costimulated with both pathophysiological flows mimicking shear stress levels found in the human aorta (laminar and turbulent, ranging from 2.5 to 30 dynes/cm2) and clinically relevant antiproliferative drugs, namely paclitaxel and rapamycin. EC state in response to these stimuli was defined using single-cell RNA sequencing.

RESULTS

We identified differentially expressed genes and inferred the TF (transcription factor) landscape modulated by flow shear stress using single-cell RNA sequencing. These flow-sensitive markers differentiated previously identified spatially distinct subpopulations of ECs in the murine aorta. Moreover, distinct transcriptional modules defined flow- and drug-responsive EC adaptation singly and in combination. Flow shear stress was the dominant driver of EC state, altering their response to pharmacological therapies.

CONCLUSIONS

We showed that flow shear stress modulates the cellular capacity of ECs to respond to paclitaxel and rapamycin administration, suggesting that while responding to different flow patterns, ECs experience an impairment in their transcriptional adaptation to other stimuli.

Ultrasound-Assessed Lesion Morphology and Drug-Coated Balloon Treatment for de novo Dysfunctional Arteriovenous Fistula in Hemodialysis Patients

AIM

This study aimed to evaluate the effect of ultrasound-assessed lesion morphology on the outcomes of drug-coated balloon (DCB) versus plain old balloon angioplasty (POBA) treatment for de novo dysfunctional arteriovenous fistulas (AVF) lesions.

METHODS

This single-center retrospective study enrolled 114 consecutive patients (mean age, 73 ± 10 years; male, 69%) with de novo dysfunctional AVF lesions who underwent percutaneous transluminal angioplasty (PTA) using DCB (n = 48) and POBA (n = 66). The morphology of the stenotic lesions, evaluated using ultrasonography, was classified into intimal hyperplasia and shrinking types. The outcome measure was 12-month primary patency. Factors associated with loss of primary patency were evaluated using Cox proportional hazards models.

RESULTS

The baseline characteristics were not significantly different between the 2 treatment groups. The 12-month primary patency rate was significantly higher in the DCB group than in the POBA group (66.8 ± 7.1% versus 35.9 ± 6.3%, P = .006). The 12-month primary patency rate in the lesions with intimal hyperplasia type was not significantly different (DCB: 70.3 ± 9.5% versus POBA: 45.9 ± 8.0%; P = .310), whereas that in the shrinking type was significantly higher in the DCB group than in the POBA group (61.9 ± 10.6% versus 15.2 ± 8.1%; P < .001). The interaction analysis demonstrated that lesion morphology had a significantly different hazard ratio (HR) for restenosis between the POBA and DCB groups (P for interaction = .031). The multivariate analysis revealed that DCB usage (adjusted hazard ratio [aHR], 0.49; 95% confidence interval [CI]: [0.28, 0.87]; P = .015), ultrasound-assessed lesion morphology (shrinking type: aHR, 1.77; 95% CI: [1.07, 2.93]; P = .026), and location of stenosis (aHR, 2.26; 95% CI: 1.15, 4.46; P = .018) were significantly associated with AVF patency after PTA.

CONCLUSION

This study revealed that lesion morphology evaluated using ultrasonography had a differential impact on DCB and POBA outcomes. The therapeutic effect of DCB was unexpectedly confirmed in the shrinking type.

CLINICAL IMPACT

The effectiveness of DCB in inhibiting smooth muscle cell proliferation in intimal hyperplasia lesions was expected based on the known mechanism of action of paclitaxel. However the therapeutic effect of DCB was unexpectedly confirmed in the shrinking type too. We may not need to hesitate usage of DCB for shrinking type.

Cardiovascular Tissue Engineering Models for Atherosclerosis Treatment Development

In the early years of tissue engineering, scientists focused on the generation of healthy-like tissues and organs to replace diseased tissue areas with the aim of filling the gap between organ demands and actual organ donations. Over time, the realization has set in that there is an additional large unmet need for suitable disease models to study their progression and to test and refine different treatment approaches. Increasingly, researchers have turned to tissue engineering to address this need for controllable translational disease models. We review existing and potential uses of tissue-engineered disease models in cardiovascular research and suggest guidelines for generating adequate disease models, aimed both at studying disease progression mechanisms and supporting the development of dedicated drug-delivery therapies. This involves the discussion of different requirements for disease models to test drugs, nanoparticles, and drug-eluting devices. In addition to realistic cellular composition, the different mechanical and structural properties that are needed to simulate pathological reality are addressed.

Pre-clinical investigation of liquid sirolimus for local drug delivery

Introduction

Sirolimus is currently being explored as an alternative drug to paclitaxel for the treatment of peripheral artery disease (PAD). To date, sirolimus has only been used as drug coatings for stents and balloons and no studies have yet demonstrated the delivery of sirolimus in liquid form. The purpose of this pilot study was to investigate the feasibility of the delivery of liquid sirolimus into arterial segments in a benchtop peripheral artery bioreactor.

Methods

The feasibility to deliver liquid therapy was first tested on four drug delivery devices using a fluorescently tagged liquid drug and an ex vivo porcine artery benchtop model. The four devices included the Bullfrog micro-infusion device, ClearWay RX catheter, Occlusion perfusion catheter (OPC), and the targeted adjustable pharmaceutical administration system (TAPAS). Penetration of the fluorescently tagged drug was measured via microscopic imaging and quantification of the depth of drug penetration into all device-treated tissue. Based on the penetration outcome, we then selected a single device to deliver liquid sirolimus into the ex vivo porcine artery model undergoing physiological flow and pressure conditions. The liquid sirolimus-treated arteries were collected from the ex vivo bioreactor at 1- and 24-hour post-delivery and arterial drug retention analyzed by liquid chromatography-tandem mass spectrometry.

Results

Fluorescent microscopy demonstrated that drug delivery with the OPC had greater drug penetration into the medial wall as compared to other devices (OPC: 234 ± 161 µm; TAPAS: 127 ± 68 µm; ClearWay: 118 ± 77 µm; Bullfrog: 2.12 ± 3.78 µm; p = 0.098). The results of the ex vivo flow-circuit bench top model showed that the OPC device successfully delivered the liquid sirolimus at 1-hour (5.17 ± 4.48 ng/mg) and 24-hour (0.78 ± 0.55 ng/mg).

Conclusions

These results demonstrate for the first time the ability to deliver liquid sirolimus directly to the medial layer of an artery via a liquid delivery catheter.

Clinical expert consensus document on drug-coated balloon for coronary artery disease from the Japanese Association of Cardiovascular Intervention and Therapeutics

Drug-coated balloon (DCB) technology was developed to deliver the antiproliferative drugs to the vessel wall without leaving any permanent prosthesis or durable polymers. The absence of foreign material can reduce the risk of very late stent failure, improve the ability to perform bypass-graft surgery, and reduce the need for long-term dual antiplatelet therapy, potentially reducing associated bleeding complications. The DCB technology, like the bioresorbable scaffolds, is expected to be a therapeutic approach that facilitates the "leave nothing behind" strategy. Although newer generation drug-eluting stents are the most common therapeutic strategy in modern percutaneous coronary interventions, the use of DCB is steadily increasing in Japan. Currently, the DCB is only indicated for treatment of in-stent restenosis or small vessel lesions (< 3.0 mm), but potential expansion for larger vessels (≥ 3.0 mm) may hasten its use in a wider range of lesions or patients with obstructive coronary artery disease. The task force of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) was convened to describe the expert consensus on DCBs. This document aims to summarize its concept, current clinical evidence, possible indications, technical considerations, and future perspectives.

Intraplaque wiring enables drug-coated balloons to be utilized for percutaneous recanalization of chronically occluded coronary arteries

OBJECTIVES

This study aimed to determine whether drug-coated balloon (DCB) angioplasty following intraplaque wiring and the use of modified balloons is safe and effective in the percutaneous treatment of coronary chronic total occlusions (CTOs).

BACKGROUND

DCB is an alternative therapeutic option without the limitations of permanent vascular implants. However, its efficacy in CTOs has yet to be confirmed. The combination of modified balloons and DCB can be effectively applied when the intraplaque passage of the guidewire is achieved in CTOs.

METHODS

Data from 124 consecutive CTO lesions (105 patients) treated at our hospital between February 2016 and December 2020 were screened for inclusion and retrospectively analyzed. Among the 118 lesions successfully recanalized, intraplaque wiring was achieved in 108, and 85 were treated by the DCB-only approach following cutting/scoring balloon dilatation.

RESULTS

Follow-up data were available for 82 lesions (71 patients). The median occlusion length was 18.5 mm, and the J-CTO score was 1.7 ± 0.9. No in-hospital major adverse cardiac events occurred, including abrupt vessel closure. During the median 29-month follow-up period, target lesion revascularization was performed for 10 lesions. Follow-up coronary angiography (8.7 ± 3.9 months after the index procedure) was performed for 64 lesions, demonstrating late lumen loss of -0.15 mm (interquartile range -0.4 to 0.23 mm), binary restenosis (diameter stenosis ≥50%) in 12 lesions (18.8%), and late lumen enlargement in 37 (57.8%).

CONCLUSION

The DCB-only approach following the use of modified balloons is a promising strategy for coronary CTOs when intraplaque wiring is achieved.

The Ranger drug-coated balloon: advances in drug-coated technology for treatment of femoropopliteal segment arterial disease

Paclitaxel drug-coated balloons (DCBs) have been shown to improve patency and lower revascularization rates compared with plain old balloon angioplasty. DCBs continue to evolve by improving balloon-coating techniques that minimize the quantity of particles washed off into the bloodstream while maximizing drug retention and vascular-healing profile. Against this backdrop, it is clear that the future of antiproliferatives for the superficial femoral artery will focus on enhancements in device coating materials that will improve the efficiency of drug delivery. The Ranger DCB system recently gained US FDA approval for use. This review discusses the background of DCBs and how the Ranger DCB builds on these previous platforms based on experimental and clinical data.

Understudied factors in drug-coated balloon design and evaluation: A biophysical perspective

Drug-coated balloon (DCB) percutaneous interventional therapy allows for durable reopening of the narrowed lumen via physical tissue expansion and local anti-restenosis drug delivery, providing an alternative to traditional uncoated balloons or a permanent indwelling implant such as a conventional metallic drug-eluting stent. While DCB-based treatment of peripheral arterial disease (PAD) has been incorporated into clinical guidelines, DCB use has been recently curtailed due to reports that showed evidence of increased mortality risk in patients treated with paclitaxel (PTX)-coated balloons. Given the United States Food and Drug Administration's 2019 consequent warning regarding PTX-eluting DCBs and the subsequent marked reduction in clinical DCB use, there is now a critical need to better understand the compositional and mechanical factors underlying DCB efficacy and safety. Most work to date on DCB refinement has focused on designing both the enabling balloon catheter and alternate coatings composed of various drugs and excipients, followed by device evaluation in preclinical and clinical studies. We contend that improvement in DCB performance will require a better understanding of the biophysical factors operative during and following balloon deployment, and moreover that the elaboration and demonstrated control of these factors are needed to address current concerns with DCB use. This article provides a perspective on the biophysical interactions that govern DCB performance and offers new design strategies for the development of next-generation DCB devices.

Modeling Dual Drug Delivery from Eluting Stents: The Influence of Non-Linear Binding Competition and Non-Uniform Drug Loading

OBJECTIVE

There is increasing interest in simultaneous endovascular delivery of more than one drug from a drug-loaded stent into a diseased artery. There may be an opportunity to obtain a therapeutically desirable uptake profile of the two drugs over time by appropriate design of the initial drug distribution in the stent. Due to the non-linear, coupled nature of diffusion and reversible specific/non-specific binding of both drugs as well as competition between the drugs for a fixed binding site density, a comprehensive numerical investigation of this problem is critically needed.

METHODS

This paper presents numerical computation of dual drug delivery in a stent-artery system, accounting for diffusion as well as specific and non-specific reversible binding. The governing differential equations are discretized in space, followed by integration over time using a stiff numerical solver. Three different cases of initial dual drug distribution are considered.

RESULTS

For the particular case of sirolimus and paclitaxel, results show that competition for a limited non-specific binding site density and the significant difference in the forward/backward reaction coefficients play a key role in determining the nature of drug uptake. The nature of initial distribution of the two drugs in the stent is also found to influence the binding process, which can potentially be used to engineer a desirable dual drug uptake profile.

CONCLUSIONS

These results help improve the fundamental understanding of endovascular dual drug delivery. In addition, the numerical technique and results presented here may be helpful for designing and optimizing other drug delivery problems as well.

How does the Nature of an Excipient and an Atheroma Influence Drug-Coated Balloon Therapy?

The advent of drug-eluting stents and drug-coated balloons have significantly improved the clinical outcome of patients with vascular occlusions. However, ischemic vascular disease remains the most common cause of death worldwide. Improving the current treatment modalities demands a better understanding of the processes which govern drug uptake and retention in blood vessels. In this study, we evaluated the influence of urea and butyryl-trihexyl citrate, as excipients, on the efficacy of drug-coated balloon therapy. An integrated approach, utilizing both in-vitro and in-silico methods, was used to quantify the tracking loss, vessel adhesion, drug release, uptake, and distribution associated with the treatment. Moreover, a parametric study was used to evaluate the potential influence of different types of lesions on drug-coated balloon therapy. Despite the significantly higher tracking loss (urea: 35.5% vs. butyryl-trihexyl citrate: 8.13%) observed in the urea-based balloons, the drug uptake was almost two times greater than with its hydrophobic counterpart. Non-calcified lesions were found to delay the transmural propagation of sirolimus while calcification was shown to limit the retentive potential of lesions. Ultimately this study helps to elucidate how different excipients and types of lesions may influence the efficacy of drug-coated balloon therapy.

Drug-Eluting Stents

Endovascular revascularization strategies have advanced tremendously over the years and are now often considered first line for treatment of peripheral arterial disease. Drug-eluting stents (DESs) have been developed as one of the tools to overcome the limitations of elastic recoil and neointimal hyperplasia observed with balloon angioplasty and bare metal stents. While these stents have been extremely successful in coronary revascularization, they have not translated as effectively to the peripheral arteries which differ in their unique mechanical environments and differences in vessel and lesion composition. DESs, through their embedded pharmaceutical agent, seek to inhibit vascular smooth muscle cell (VSMC) proliferation and migration. Paclitaxel, sirolimus, and its derivatives (-limus family) achieve VSMC inhibition through unique mechanisms. Several clinical trials have been performed to evaluate the use of DES in the femoropopliteal and infrapopliteal territory and have demonstrated overall decrease in revascularization rates and improved clinical outcomes.

Treatment of Coronary De Novo Lesions by a Sirolimus- or Paclitaxel-Coated Balloon

OBJECTIVES

The aim of this randomized controlled trial was to investigate a novel sirolimus-coated balloon (SCB) compared with the best investigated paclitaxel-coated balloon (PCB).

BACKGROUND

There is increasing clinical evidence for the treatment of coronary de novo disease using drug-coated balloons. However, it is unclear whether paclitaxel remains the drug of choice or if sirolimus is an alternative, in analogy to drug-eluting stents.

METHODS

Seventy patients with coronary de novo lesions were enrolled in a randomized, multicenter trial to compare a novel SCB (SeQuent SCB, B. Braun Melsungen; 4 μg/mm²) with a PCB (SeQuent Please, B. Braun Melsungen; 3 μg/mm²). The primary endpoint was angiographic late lumen loss (LLL) at 6 months. Secondary endpoints included major adverse cardiovascular events and individual clinical endpoints such as cardiac death, target lesion myocardial infarction, clinically driven target lesion revascularization, and binary restenosis.

RESULTS

Quantitative coronary angiography revealed no differences in baseline parameters. After 6 months, in-segment LLL was 0.01 ± 0.33 mm in the PCB group versus 0.10 ± 0.32 mm in the SCB group. The mean difference between SCB and PCB was 0.08 (95% CI: -0.07 to 0.24). Noninferiority at a predefined margin of 0.35 was shown. However, negative LLL was more frequent in the PCB group (60% of lesions vs 32% in the SCB group; P = 0.019). Major adverse cardiovascular events up to 12 months also did not differ between the groups.

CONCLUSIONS

This first-in-human comparison of a novel SCB with a crystalline coating showed similar angiographic outcomes in the treatment of coronary de novo disease compared with a clinically proven PCB. However, late luminal enlargement was more frequently observed after PCB treatment. (Treatment of Coronary De-Novo Stenosis by a Sirolimus Coated Balloon or a Paclitaxel Coated Balloon Catheter Malaysia [SCBDNMAL]; NCT04017364).

An Implantable Artificial Atherosclerotic Plaque as a Novel Approach for Drug Transport Studies on Drug-Eluting Stents

Atherosclerotic arteries are commonly treated using drug-eluting stents (DES). However, it remains unclear whether and how the properties of atherosclerotic plaque affect drug transport in the arterial wall. A limitation of the currently used atherosclerotic animal models to study arterial drug distribution is the unpredictability of plaque size, composition, and location. In the present study, the aim is to create an artificial atherosclerotic plaque-of reproducible and controllable complexity and implantable at specific locations-to enable systematic studies on transport phenomena of drugs in stented atherosclerosis-mimicking arteries. For this purpose, mixtures of relevant lipids at concentrations mimicking atherosclerotic plaque are incorporated in gelatin/alginate hydrogels. Lipid-free (control) and lipid-rich hydrogels (artificial plaque) are created, mounted on DES and successfully implanted in porcine coronary arteries ex-vivo. Matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) is used to measure local drug distribution in the arterial wall behind the prepared hydrogels, showing that the lipid-rich hydrogel significantly hampers drug transport as compared to the lipid-free hydrogel. This observation confirms the importance of studying drug transport phenomena in the presence of lipids and of having an experimental model in which lipids and other plaque constituents can be precisely controlled and systematically studied.

Paclitaxel and mortality in patients with claudication and de novo femoropopliteal lesions: a historical cohort study

Objective

To compare the mortality rates of patients with claudication and de novo femoropopliteal lesions treated with and without paclitaxel coated devices (PCD).

Background

A recent meta-analysis, mostly including patients with claudication and de novo femoropopliteal lesions but also with recurrent stenoses and critical limb ischemia, has shown a significant excess mortality in patients treated with PCD.

Methods

Comparison of two historical cohorts of patients presenting with claudication and de novo femoropopliteal lesions treated with and without PCD between 2008 and 2018.

Results

After review of 5219 arteriograms in patients presenting with peripheral artery disease, 700 consecutive patients were included consisting in 72.6% of male (n = 508). Mean age was 68.1 ± 8.5 years. 45.7% of the patients (n = 320) had a treatment including a PCD. Mean femoropopliteal lesion length was 123 ± 91 mm including 44.6% of occlusions. Patients of the control group were censored at crossover to paclitaxel when applicable. Mortality rates at 1, 2 and 5 years were 4.6%, 7.5%, 19.4% and 1.6%, 6.2%, 16.6% in the non-PCD and PCD groups respectively. The relative risks of death when using PCD were 0.35 (p = 0.03), 0.83 (p = NS) and 0.86 (p = NS) at 1, 2 and 5 years respectively.

Conclusion

There was no excess mortality in patients with claudication and de novo femoropopliteal lesions treated with paclitaxel coated devices at 1, 2 and 5 years of follow-up in this cohort. The current study suggests that additional prospective randomized studies properly powered to study mortality are necessary.

Vascular Lesion-Specific Drug Delivery Systems: JACC State-of-the-Art Review

Drug delivery is central to modern cardiovascular care, where drug-eluting stents, bioresorbable scaffolds, and drug-coated balloons all aim to restore perfusion while inhibiting exuberant healing. The promise and enthusiasm of these devices has in some cases exceeded demonstration of efficacy and even understanding of driving mechanisms. The authors review the means of drug delivery in each device, outlining how the technologies affect vascular behavior. They focus on how drug retention and response are governed by lesion morphology: lipid displacing drug-specific binding sites, calcium inhibiting diffusion, blocking thrombi or promoting luminal washout, and vascular healing steering hyperplastic developments. In this regard, the authors outline the fundamental impact of vascular structure on drug delivery and review the development of contemporary and future devices for coronary and peripheral intervention. They look toward a future where incorporating information on lesion distribution is central to therapeutic success and envision a transition toward lesion-specific treatment for improved interventional outcomes.

Influence of Elongation of Paclitaxel-Eluting Electrospun-Produced Stent Coating on Paclitaxel Release and Transport through the Arterial Wall after Stenting

It was previously shown that polycaprolactone (PCL)-based electrospun-produced paclitaxel (PTX)-enriched matrices exhibit long-term drug release kinetics and can be used as coatings for drug-eluting stents (DES). The installation of vascular stents involves a twofold increase in stent diameter and, therefore, an elongation of the matrices covering the stents, as well as the arterial wall in a stented area. We studied the influence of matrix elongation on its structure and PTX release using three different electrospun-produced matrices. The data obtained demonstrate that matrix elongation during stent installation does not lead to fiber breaks and does not interfere with the kinetics of PTX release. To study PTX diffusion through the expanded artery wall, stents coated with 5%PCL/10%HSA/3%DMSO/PTX and containing tritium-labeled PTX were installed into the freshly obtained iliac artery of a rabbit. The PTX passing through the artery wall was quantified using a scintillator β-counter. The artery retained the PTX and decreased its release from the coating. The retention of PTX by the arterial wall was more efficient when incubated in blood plasma in comparison with PBS. The retention/accumulation of PTX by the arterial wall provides a prolonged drug release and allows for the reduction in the dose of the drugs in electrospun-produced stent coatings.

Significant difference between sirolimus and paclitaxel nanoparticles in anti-proliferation effect in normoxia and hypoxia: The basis of better selection of atherosclerosis treatment

Compared with paclitaxel, sirolimus has been more used in the treatment of vascular restenosis gradually as an anti-proliferative drug, but few basic studies have elucidated its mechanism. The anti-proliferative effects of sirolimus or paclitaxel have been demonstrated by numerous studies under normoxia, but few studies have been achieved focusing hypoxia. In this study, porcine carotid artery injury model and classical cobalt chloride hypoxia cell model were established. Sirolimus nanoparticles (SRM-NPs), paclitaxel nanoparticles (PTX-NPs) and blank nanoparticles (Blank-NPs) were prepared respectively. The effect of RPM-NPs on the degree of stenosis, proliferative index and the expression of PCNA after 28 days of porcine carotid artery injury model was evaluated. Compared with saline group and SRM groups, SRM-NPs group suppressed vascular stenosis, proliferative index and the expression of PCNA (P < 0.01 and P < 0.05). Endothelial cell (EC) and smooth muscle cell (SMC) were pre-treated with cobaltous chloride, followed by SRM-NPs, PTX-NPs, Blank-NPs or PBS control treating, the effects on cell proliferation, HIF-1 expression and glycolysis were detected. SRM-NPs could inhibit EC and SMC proliferation under hypoxia, while PTX-NPs couldn't (P < 0.001). Significant differences between sirolimus and paclitaxel NPs in anti-proliferation effect under normoxia and hypoxia may due to the different inhibitory effects on HIF-1α expression and glycolysis. In conclusion, these results suggest that sirolimus can inhibit the proliferation of hypoxic cells more effectively than paclitaxel. These observations may provide a basis for understanding clinical vascular stenosis therapeutic differences between rapamycin and paclitaxel.

Influence of vessel curvature and plaque composition on drug transport in the arterial wall following drug-eluting stent implantation

In the last decade, many computational models have been developed to describe the transport of drug eluted from stents and the subsequent uptake into arterial tissue. Each of these models has its own set of limitations: for example, models typically employ simplified stent and arterial geometries, some models assume a homogeneous arterial wall, and others neglect the influence of blood flow and plasma filtration on the drug transport process. In this study, we focus on two common limitations. Specifically, we provide a comprehensive investigation of the influence of arterial curvature and plaque composition on drug transport in the arterial wall following drug-eluting stent implantation. The arterial wall is considered as a three-layered structure including the subendothelial space, the media and the adventitia, with porous membranes separating them (endothelium, internal and external elastic lamina). Blood flow is modelled by the Navier-Stokes equations, while Darcy's law is used to calculate plasma filtration through the porous layers. Our findings demonstrate that arterial curvature and plaque composition have important influences on the spatiotemporal distribution of drug, with potential implications in terms of effectiveness of the treatment. Since the majority of computational models tend to neglect these features, these models are likely to be under- or over-estimating drug uptake and redistribution in arterial tissue.

Possible mechanism of late lumen enlargement after treatment for de novo coronary lesions with drug-coated balloon

BACKGROUND

Drug-coated balloon (DCB) treatment for de novo coronary artery disease has demonstrated late lumen enlargement (LLE) in mid-term follow-up and it was considered as clinical benefit; however, its mechanism and the predictive factor remains unclear.

METHODS

This study enrolled 46 consecutive patients (54 lesions) treated with DCB, using intravascular ultrasound (IVUS) at the index procedure and at the 9-month follow-up. We measured IVUS parameters at 1-mm intervals and calculated the mean volume of the external elastic membrane (EEM), lumen, and plaque. We calculated the dissection index (DI) defined as summation of the following points, 2: dissection over EEM, 1: intra-EEM dissection, 0: no dissection at every 1-mm interval, and divided by lesion length.

RESULTS

IVUS showed that there was no flow limiting dissection just after DCB treatment, the mean EEM and lumen volume (LV) had significantly increased while mean plaque volume had significantly decreased at 9 months, and 74.1% lesions exhibited LLE. We divided the patients into three groups according to delta mean LV. Mean EEM volume significantly increased and mean plaque volume significantly decreased in the larger and smaller LLE groups, but not in the non-LLE group. The DI was higher in a descending order in the three groups. The multiple regression analysis demonstrated that the DI was the strongest predictor of the change in mean LV.

CONCLUSIONS

LLE after DCB treatment may be caused by vessel enlargement and plaque regression. The non-flow limiting larger dissection just after DCB treatment may strongly associate with the intending LLE.

Balloon-based drug coating delivery to the artery wall is dictated by coating micro-morphology and angioplasty pressure gradients

Paclitaxel coated balloon catheters (PCB) were developed as a polymer-free non-implantable alternative to drug eluting stents, delivering similar drug payloads in a matter of minutes. While PCB have shown efficacy in treating peripheral arterial disease in certain patient groups, restenosis rates remain high and there is no class effect. To help further optimize these devices, we developed a scanning electron microscopy (SEM) imaging technique and computational modeling approach that provide insights into the coating micromorphology dependence of in vivo drug transfer and retention. PCBs coated with amorphous/flaky or microneedle coatings were inflated for 60 sec in porcine femoral arteries. Animals were euthanized at 0.5, 24 and 72 h and treated arteries processed for SEM to image endoluminal coating distribution followed by paclitaxel quantification by mass spectrometry (MS). Endoluminal surfaces exhibited sparse coating patches at 0.5 h, predominantly protruding (13.71 vs 0.59%, P < 0.001), with similar micro-morphologies to nominal PCB surfaces. Microneedle coating covered a 1.5-fold endoluminal area (16.1 vs 10.7%, P = 0.0035) owing to higher proximal and distal delivery, and achieved 1.5-fold tissue concentrations by MS (1933 vs 1298 μg/g, P = 0.1745) compared to amorphous/flaky coating. Acute longitudinal coating distribution tracked computationally predicted microindentation pressure gradients (r = 0.9, P < 0.001), with superior transfer of the microneedle coatings attributed to their amplification of angioplasty contact pressures. By 24 h, paclitaxel concentration and coated tissue areas both declined by >93% even as nonprotruding coating levels were stable between 0.5 and 72 h, and 2.7-fold higher for microneedle vs flaky coating (0.64 vs 0.24%, P = 0.0195). Tissue retained paclitaxel concentrations at 24-72 h trended 1.7-fold higher post treatment with microneedle coating compared to the amorphous/flaky coating (69.9 vs 39.9 μg/g, P = 0.066). Thus, balloon based drug delivery is critically dependent on coating micromorphologies, with superior performance exhibited by micromorphologies that amplify angioplasty pressures.

Treatment of Coronary Drug-Eluting Stent Restenosis by a Sirolimus- or Paclitaxel-Coated Balloon

OBJECTIVES

The aim of this randomized controlled trial was to investigate a novel sirolimus-coated balloon (SCB) compared with the best investigated paclitaxel-coated balloon (PCB).

BACKGROUND

Treatment of coronary in-stent restenosis (ISR) remains challenging. PCBs are an established treatment option outside the United States with a Class I, Level of Evidence: A recommendation in the European guidelines. However, their efficacy is better in bare-metal stent (BMS) ISR compared with drug-eluting stent (DES) ISR.

METHODS

Fifty patients with DES ISR were enrolled in a randomized, multicenter trial to compare a novel SCB (SeQuent SCB, 4 μg/mm²) with a clinically proven PCB (SeQuent Please Neo, 3 μg/mm²) in coronary DES ISR. The primary endpoint was angiographic late lumen loss at 6 months. Secondary endpoints included procedural success, major adverse cardiovascular events, and individual clinical endpoints such as stent thrombosis, cardiac death, target lesion myocardial infarction, clinically driven target lesion revascularization, and binary restenosis.

RESULTS

Quantitative coronary angiography revealed no differences in baseline parameters. After 6 months, in-segment late lumen loss was 0.21 ± 0.54 mm in the PCB group versus 0.17 ± 0.55 mm in the SCB group (p = NS; per-protocol analysis). Clinical events up to 12 months also did not differ between the groups.

CONCLUSIONS

This first-in-man comparison of a novel SCB with a crystalline coating shows similar angiographic outcomes in the treatment of coronary DES ISR compared with a clinically proven PCB. (Treatment of Coronary In-Stent Restenosis by a Sirolimus [Rapamycin] Coated Balloon or a Paclitaxel Coated Balloon [FIM LIMUS DCB]; NCT02996318).

Mortality and Paclitaxel-Coated Devices: An Individual Patient Data Meta-Analysis

BACKGROUND

Paclitaxel-containing devices (PTXDs) significantly reduce reintervention in patients with symptomatic femoropopliteal peripheral artery disease. A recent aggregate-data meta-analysis reported increased late mortality in patients with peripheral artery disease treated with PTXDs. We performed an individual patient data meta-analysis to evaluate mortality.

METHODS

Manufacturers of US Food and Drug Administration-approved and commercially available devices in the United States provided deidentified individual patient data for independent analysis. Cox proportional hazards 1-stage meta-analysis models using intention-to-treat methods were used for the primary analysis. A secondary analysis of recovered missing vital status data was performed. The impact of control crossover to PTXDs, cause-specific mortality, and drug dose mortality were assessed.

RESULTS

A total of 2185 subjects and 386 deaths from 8 PTXD trials with 4-year median follow-up were identified. The primary analysis indicated a 38% (95% CI, 6% to 80%) increased relative mortality risk, corresponding to 4.6% absolute increase, at 5 years associated with PTXD use. Control and treatment arm loss to follow-up and withdrawal were 24% and 23%, respectively. With inclusion of recovered vital status data, the excess relative mortality risk was 27% (95% CI, 3%-58%). This observation was consistent across various scenarios, including as-treated analyses, with no evidence of increased risk over time with PTXDs. Mortality risk tended to be increased for all major causes of death. There were no subgroup differences. No drug dose-mortality association was identified.

CONCLUSIONS

This individual patient data meta-analysis, based on the most complete available data set of mortality events from PTXD randomized controlled trials, identified an absolute 4.6% increased mortality risk associated with PTXD use.

Adventitial injection delivery of nano-encapsulated sirolimus (Nanolimus) to injury-induced porcine femoral vessels to reduce luminal restenosis

Endovascular therapy in peripheral intervention has grown exponentially in the past decade, but the issue of high restenosis rates in lower extremity arteries still persist. While drug-coated balloons (DCB) have been the device of choice, recent controversary regarding the long-term safety of paclitaxel have raised concern over current DCBs. In our study, we proposed that the direct injection of a sirolimus nanoliposomal formulation (Nanolimus) using a infusion catheter can attenuate inflammation response in injured vessels. In vitro characterization showed retention of the nanoliposomes size and detectable drug amount up to 336 days in storage. For in vivo study, four female, mixed breed swines were subjected to balloon injury of the femoral arteries before treatment with either injection of saline (n = 4) or Nanolimus (n = 12) using the Bullfrog catheter. Pharmacokinetic analysis demonstrated sustained sirolimus release in the arteries and undetectable systemic drug level at 28 days. Arteries treated with Nanolimus showed significant reduction in neointima area (0.2 ± 0.3 mm² vs 2.0 ± 1.2 mm², p < 0.01) and luminal stenosis (14.2 ± 7.2% vs. 67.7 ± 24.8%, p < 0.01) compared to controls. In summary, adventitial delivery of sirolimus using an infusion catheter is a feasible and safe method to reduce vascular restenosis.

Mortality Assessment of Paclitaxel-Coated Balloons: Patient-Level Meta-Analysis of the ILLUMENATE Clinical Program at 3 Years

BACKGROUND

A recent summary-level meta-analysis comprising randomized, controlled trials (RCTs) of femoropopliteal paclitaxel-coated balloon and stent intervention identified excess late mortality in the paclitaxel-treated patients.

METHODS

We evaluated the safety of the Stellarex drug-coated balloon (DCB) for femoropopliteal artery disease with an independently performed meta-analysis of patient-level data from all patients in the Stellarex femoropopliteal clinical program. To compare mortality after DCB or uncoated percutaneous transluminal angioplasty (PTA), we aggregated data from 2 RCTs comprising 419 patients treated with DCB and 170 patients treated with PTA. In an additional analysis, data were aggregated from 6 poolable Stellarex DCB studies (2 RCTs, 3 single-arm studies, and 1 registry). All serious adverse events including deaths were adjudicated by a blinded, third-party, independent Clinical Events Committee. Kaplan-Meier estimates in the RCTs were compared with restricted mean survival time. Predictors of death were assessed with hazard ratios (HRs) and Cox proportional hazards modeling.

RESULTS

Baseline characteristics were similar in the patients treated with DCB and PTA in the pooled RCT analysis, with the exception that the DCB cohort was younger (67.4±9.7 versus 69.4±9.4 years, P=0.02), smoked more frequently (86.6% versus 78.8%, P=0.02), and were less often treated for recurrent lesions (8.8% versus 14.7%, P=0.04). In the RCTs, patients treated with DCB had all-cause mortality rates that were not different from those of patients treated with PTA (Kaplan-Meier estimates 1.8±0.7% versus 1.3±0.9%, 6.5±1.2% versus 5.9±1.9%, and 9.3±1.5% versus 9.9±2.4% at 1, 2, and 3 years, respectively, P=0.86). All-cause mortality rates were similar in a 1906-patient pooled nonrandomized DCB data set (Kaplan-Meier estimates of 2.1%, 4.9%, and 7.0% at 1, 2, and 3 years, respectively). Clinical Events Committee-adjudicated causes of death were balanced between the DCB and PTA cohorts. Multivariable Cox modeling identified age (HR, 1.06; 95% CI, 1.04-1.08; P<0.001), diabetes mellitus (HR, 1.42; 95% CI, 1.01-2.00; P=0.04), congestive heart failure (HR, 1.88; 95% CI, 1.12-3.16; P=0.02), and renal insufficiency (HR, 2.00; 95% CI, 1.33-3.01; P<0.001) as predictors of mortality. Paclitaxel exposure was unrelated to mortality (HR, 1.04; 95% CI, 0.98-1.10; P=0.23).

CONCLUSIONS

The mortality rates for patients treated with the DCB and uncoated PTA were indistinguishable over 3-year follow-up. Additional patient-level, adequately powered meta-analyses with larger RCT data sets will be needed to confirm the generalizability of these findings.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifiers: NCT02110524, NCT01858363, NCT01858428, NCT03421561, NCT01912937, NCT01927068, and NCT02769273.

Taking paclitaxel coated balloons to a higher level: Predicting coating dissolution kinetics, tissue retention and dosing dynamics

Paclitaxel coated balloons (PCBs) are a promising non-implantable alternative to drug-eluting stents, whereby drug is delivered to the arterial wall in solid form as a semi-continuous solid coating or as micro drug depots. To date, it has been impossible to predict or even infer local tissue dosing levels and persistence, making it difficult to compare in vivo performance of different devices in healthy animals or to extrapolate such data to diseased human arteries. Here we derive and analyze a coupled reaction diffusion model that accounts for coating dissolution and tissue distribution, and predicts the concentration of dissolved drug in the tissue during and post dissolution. Time scale analysis and numerical simulations based on estimated diffusion coefficients in healthy animal and diseased human arteries both imply that dissolution of crystalline paclitaxel coating is mass transfer coefficient-limited, and can therefore be solved for independently of the tissue transport equations. Specifically, coating retention is predicted to follow piecewise linear kinetics, reflecting the differential and faster dissolution of lumenal versus tissue-embedded coating owing to a disparity in convective forces. This prediction is consistent with published data on a range of PCBs and allowed for the estimation of the associated dissolution rate-constants and the maximal soluble drug concentration in the tissue during coating dissolution. Maximal soluble drug concentration in the tissue scales as the product of the solubility and ratio of the dissolution and diffusion rate-constants. Thus, coatings characterized by micromolar solubilities give rise to nanomolar soluble concentrations in healthy animal arteries and ~0.1 micromolar in calcified atherosclerotic arteries owing to slower tissue diffusion. During dissolution, retention in porcine iliofemoral arteries is predicted to be dominated by solid coating, whereas post dissolution it is dominated by receptor-bound drug (3.7 ng receptors/g tissue). Paclitaxel coating dissolution and dosing kinetics can now be modeled based upon accepted principles of surface dissolution and tissue transport to provide insights into the dependence of clinical efficacy on device properties and the interplay of lesion complexity and procedural parameters.

Targeted Delivery of Bioactive Molecules for Vascular Intervention and Tissue Engineering

Cardiovascular diseases are the leading cause of death in the United States. Treatment often requires surgical interventions to re-open occluded vessels, bypass severe occlusions, or stabilize aneurysms. Despite the short-term success of such interventions, many ultimately fail due to thrombosis or restenosis (following stent placement), or incomplete healing (such as after aneurysm coil placement). Bioactive molecules capable of modulating host tissue responses and preventing these complications have been identified, but systemic delivery is often harmful or ineffective. This review discusses the use of localized bioactive molecule delivery methods to enhance the long-term success of vascular interventions, such as drug-eluting stents and aneurysm coils, as well as nanoparticles for targeted molecule delivery. Vascular grafts in particular have poor patency in small diameter, high flow applications, such as coronary artery bypass grafting (CABG). Grafts fabricated from a variety of approaches may benefit from bioactive molecule incorporation to improve patency. Tissue engineering is an especially promising approach for vascular graft fabrication that may be conducive to incorporation of drugs or growth factors. Overall, localized and targeted delivery of bioactive molecules has shown promise for improving the outcomes of vascular interventions, with technologies such as drug-eluting stents showing excellent clinical success. However, many targeted vascular drug delivery systems have yet to reach the clinic. There is still a need to better optimize bioactive molecule release kinetics and identify synergistic biomolecule combinations before the clinical impact of these technologies can be realized.

Electrospun Produced 3D Matrices for Covering of Vascular Stents: Paclitaxel Release Depending on Fiber Structure and Composition of the External Environment

Paclitaxel is a natural, highly lipophilic anti proliferative drug widely used in medicine. We have studied the release of tritium-labeled paclitaxel (³H-PTX) from matrices destined for the coating of vascular stents and produced by the electrospinning method from the solutions of polycaprolactone (PCL) with paclitaxel (PTX) in hexafluoisopropanol (HFIP) and/or solutions of PCL with PTX and human serum albumin (HSA) in HFIP or HIFP-dimethyl sulphoxide (DMSO) blend. The release of PTX has been shown to depend on the composition of electrospinning solution, as well as the surrounding medium, particularly the concentration of free PTX and PTX-binding biomolecules present in human serum. It was shown that 3D matrices can completely release PTX without weight loss. Two-phase PTX release from optimized 3D matrices was obtained: ~27% of PTX was released in the first day, another 8% were released over the next 26 days. Wherein ~2.8%, ~2.3%, and ~0.25% of PTX was released on day 3, 9, and 27, respectively. Considering PTX toxicity, the rate of its diffusion through the arterial wall, and the data obtained the minimum cytostatic dose of the drug in the arterial wall will be maintained for at least three months.