Advancing material property prediction: using physics-informed machine learning models for viscosity.

In materials science, accurately computing properties like viscosity, melting point, and glass transition temperatures solely through physics-based models is challenging. Data-driven machine learning (ML) also poses challenges in constructing ML models, especially in the material science domain where data is limited. To address this, we integrate physics-informed descriptors from molecular dynamics (MD) simulations to enhance the accuracy and interpretability of ML models. Our current study focuses on accurately predicting viscosity in liquid systems using MD descriptors. In this work, we curated a comprehensive dataset of over 4000 small organic molecules' viscosities from scientific literature, publications, and online databases. This dataset enabled us to develop quantitative structure-property relationships (QSPR) consisting of descriptor-based and graph neural network models to predict temperature-dependent viscosities for a wide range of viscosities. The QSPR models reveal that including MD descriptors improves the prediction of experimental viscosities, particularly at the small data set scale of fewer than a thousand data points. Furthermore, feature importance tools reveal that intermolecular interactions captured by MD descriptors are most important for viscosity predictions. Finally, the QSPR models can accurately capture the inverse relationship between viscosity and temperature for six battery-relevant solvents, some of which were not included in the original data set. Our research highlights the effectiveness of incorporating MD descriptors into QSPR models, which leads to improved accuracy for properties that are difficult to predict when using physics-based models alone or when limited data is available.

Midterm follow-up after computed tomography angiography planned left atrial appendage closure.

BACKGROUND: While studies have shown the advantages of computed tomography angiography (CTA) over transesophageal echocardiography (TEE) in left atrial appendage closure (LAAC) preprocedural planning for WATCHMAN™ legacy and FLX devices, there has been no reported long-term data for this approach. OBJECTIVES: We sought to evaluate long-term outcomes using CTA-based preprocedural planning for LAAC using the WATCHMAN™ device. METHODS: A prospective analysis of 231 consecutive patients who underwent LAAC in a single, large academic hospital in the United States was conducted over a 5-year period. CTA-guided preprocedural planning was performed in all. Procedural success, adverse events, length of procedure, number of devices used, and length of stay were evaluated. Rates of death, cerebral embolism, systemic embolism, and major and minor bleeding were recorded. Adjusted predicted stroke and major bleeding rates were derived from CHA2DS2-Vasc and HAS-BLED scores, respectively. RESULTS: From January 26, 2017, to November 23, 2021, 231 patients underwent LAAC with CTA preprocedural planning by two operating physicians. The mean age of patients was 76.5 ± 8.4. 59.7% of patients were male. Mean CHA2DS2VASc and HAS-BLED scores were 4.5 ± 1.4 and 3.9 ± 0.9, respectively. All procedures were performed with intracardiac echo (100%). The procedural success rate was 99.1%. The CTA sizing strategy accurately predicted the implant size in 93.5% of patients. Mean number of devices used was 1.10 ± 0.3. Peri-procedural complication rate was 2.2%. 6 patients were lost to follow-up. Mean follow-up was 608.94 days with a total of 377.04 patient years. Median follow-up period of 368 days (interquartile range: 209-1067 days). There were 51 deaths from all causes (13.52 per 100 patient-years), 10 cases of cerebral embolism (2.65 per 100 patient-years), 2 cases of systemic embolism (0.53 per 100 patient-years), 17 cases of major bleeding (4.50 per 100 patient-years), and 31 cases of minor bleeding (8.2 per 100 patient-years). All-cause mortality at 1, 2, and 3 years was 12.7%, 20.9%, and 29.2%, respectively. CV event rates at 1, 2, and 3 years were 2.1%, 6.6%, and 10.5%, respectively. CONCLUSIONS: CTA-based preprocedural planning is accurate in predicting device size for LAAC and associated with excellent clinical outcomes at 5 years.

Development of scalable and generalizable machine learned force field for polymers.

Understanding and predicting the properties of polymers is vital to developing tailored polymer molecules for desired applications. Classical force fields may fail to capture key properties, for example, the transport properties of certain polymer systems such as polyethylene glycol. As a solution, we present an alternative potential energy surface, a charge recursive neural network (QRNN) model trained on DFT calculations made on smaller atomic clusters that generalizes well to oligomers comprising larger atomic clusters or longer chains. We demonstrate the validity of the polymer QRNN workflow by modeling the oligomers of ethylene glycol. We apply two rounds of active learning (addition of new training clusters based on current model performance) and implement a novel model training approach that uses partial charges from a semi-empirical method. Our developed QRNN model for polymers produces stable molecular dynamics (MD) simulation trajectory and captures the dynamics of polymer chains as indicated by the striking agreement with experimental values. Our model allows working on much larger systems than allowed by DFT simulations, at the same time providing a more accurate force field than classical force fields which provides a promising avenue for large-scale molecular simulations of polymeric systems.

Effects of tidal cycle on greenhouse gases emissions from a tropical estuary.

The potential effects of tidal and diel cycles on fluxes and concentrations of carbon dioxide (pCO2), methane (CH4), and nitrous oxide (N2O) along with associated biogeochemical processes remain poorly understood in tropical estuaries. The present study, based on six-hourly sampling for nine consecutive days at three locations along the salinity gradient in the Mahanadi estuary of India, revealed that the tidal forcing affected pCO2 and CH4 in the mixing zone with elevated concentrations during low tide with maximum concentrations up to 21,606 µatm and 285 µM, respectively. pCO2 increased with decrease in tidal height within low and high tide duration as well, possibly due to higher relative contribution of freshwater with high CO2. N2O, on the other hand, showed no significant variability with tidal cycle or water level fluctuation during high and low tide. Barring the offshore region, the study area was source of greenhouse gases to the atmosphere.

Novel computed tomography angiography-based sizing methodology for WATCHMAN FLX device in left atrial appendage closure.

BACKGROUND: While there is recent data suggesting an advantage of computed tomography angiography (CTA) over transesophageal echocardiography (TEE) for preprocedural left atrial appendage closure (LAAC) planning, there is limited published experience for sizing strategies. Device sizing for LAAC may be challenging and noninvasive algorithms that improve this selection process are warranted. OBJECTIVES: We sought to evaluate the safety and the feasibility for the implementation of a novel CTA-based sizing methodology for WATCHMAN™ FLX device in a series of patients undergoing LAAC using the TruPlan™ software package. METHODS: A prospective analysis of 136 consecutive patients who underwent LAAC over a 12-month period in a single, large academic hospital in the United States was conducted. CTA-guided preprocedural planning and intracardiac echocardiography (ICE) was performed in all. Procedural success, adverse events, length of procedure, number of devices used, and length of stay were evaluated. RESULTS: A total of 136 patients who underwent LAAC procedure with WATCHMAN™ FLX platform between October 1, 2020 until September 30, 2021 were included. The pre-specified protocol using CTA and ICE was implemented in all patients (100%). Mean CHA2 DS2 VASc score was 4.4 ± 1.3 and the mean HAS-BLED score was 3.9 ± 0.8. ICE-guided 100% transseptal puncture success rate was 100% with 98.5% of overall procedural success rate. Preprocedural CTA sizing strategy accurately predicted the implanted size in 91.1% of patients. Ten patients (7.4%) required another sized device and 2 cases were aborted. At 45-day follow-up, only 1 patient (0.7%) had significant peri-device leak (≥5 mm) on TEE. CONCLUSIONS: CTA-based preprocedural sizing methodology for WATCHMAN™ FLX in LAAC was safe, feasible and associated with excellent procedural outcomes. Further studies are warranted to confirm if the features specific to TruPlan™ may reduce the number of deployment attempts, the number of devices utilized in the procedure, and the risk of complications.

SARS-CoV-2 Reinfection Rate and Estimated Effectiveness of the Inactivated Whole Virion Vaccine BBV152 Against Reinfection Among Health Care Workers in New Delhi, India.

Importance: A surge of COVID-19 occurred from March to June 2021, in New Delhi, India, linked to the B.1.617.2 (Delta) variant of SARS-CoV-2. COVID-19 vaccines were rolled out for health care workers (HCWs) starting in January 2021. Objective: To assess the incidence density of reinfection among a cohort of HCWs and estimate the effectiveness of the inactivated whole virion vaccine BBV152 against reinfection. Design, Setting, and Participants: This was a retrospective cohort study among HCWs working at a tertiary care center in New Delhi, India. Exposures: Vaccination with 0, 1, or 2 doses of BBV152. Main Outcomes and Measures: The HCWs were categorized as fully vaccinated (with 2 doses and ≥15 days after the second dose), partially vaccinated (with 1 dose or 2 doses with <15 days after the second dose), or unvaccinated. The incidence density of COVID-19 reinfection per 100 person-years was computed, and events from March 3, 2020, to June 18, 2021, were included for analysis. Unadjusted and adjusted hazard ratios (HRs) were estimated using a Cox proportional hazards model. Estimated vaccine effectiveness (1 - adjusted HR) was reported. Results: Among 15 244 HCWs who participated in the study, 4978 (32.7%) were diagnosed with COVID-19. The mean (SD) age was 36.6 (10.3) years, and 55.0% were male. The reinfection incidence density was 7.26 (95% CI: 6.09-8.66) per 100 person-years (124 HCWs [2.5%], total person follow-up period of 1696 person-years as time at risk). Fully vaccinated HCWs had lower risk of reinfection (HR, 0.14 [95% CI, 0.08-0.23]), symptomatic reinfection (HR, 0.13 [95% CI, 0.07-0.24]), and asymptomatic reinfection (HR, 0.16 [95% CI, 0.05-0.53]) compared with unvaccinated HCWs. Accordingly, among the 3 vaccine categories, reinfection was observed in 60 of 472 (12.7%) of unvaccinated (incidence density, 18.05 per 100 person-years; 95% CI, 14.02-23.25), 39 of 356 (11.0%) of partially vaccinated (incidence density 15.62 per 100 person-years; 95% CI, 11.42-21.38), and 17 of 1089 (1.6%) fully vaccinated (incidence density 2.18 per 100 person-years; 95% CI, 1.35-3.51) HCWs. The estimated effectiveness of BBV152 against reinfection was 86% (95% CI, 77%-92%); symptomatic reinfection, 87% (95% CI, 76%-93%); and asymptomatic reinfection, 84% (95% CI, 47%-95%) among fully vaccinated HCWs. Partial vaccination was not associated with reduced risk of reinfection. Conclusions and Relevance: These findings suggest that BBV152 was associated with protection against both symptomatic and asymptomatic reinfection in HCWs after a complete vaccination schedule, when the predominant circulating variant was B.1.617.2.

Molecular-Level Examination of Amorphous Solid Dispersion Dissolution.

Amorphous solid dispersions (ASDs) are commonly used to orally deliver small-molecule drugs that are poorly water-soluble. ASDs consist of drug molecules in the amorphous form which are dispersed in a hydrophilic polymer matrix. Producing a high-performance ASD is critical for effective drug delivery and depends on many factors such as solubility of the drug in the matrix and the rate of drug release in aqueous medium (dissolution), which is linked to bioperformance. Often, researchers perform a large number of design iterations to achieve this objective. A detailed molecular-level understanding of the mechanisms behind ASD dissolution behavior would aid in the screening, designing, and optimization of ASD formulations and would minimize the need for testing a wide variety of prototype formulations. Molecular dynamics and related types of simulations, which model the collective behavior of molecules in condensed phase systems, can provide unique insights into these mechanisms. To study the effectiveness of these simulation techniques in ASD formulation dissolution, we carried out dissipative particle dynamics simulations, which are particularly an efficient form of molecular dynamics calculations. We studied two stages of the dissolution process: the early-stage of the dissolution process, which focuses on the dissolution at the ASD/water interface, and the late-stage of the dissolution process, where significant drug release would have occurred and there would be a mixture of drug and polymer molecules in a predominantly aqueous environment. Experimentally, we used Fourier transform infrared spectroscopy to study the interactions between drugs, polymers, and water in the dry and wet states and the chromatographic technique to study the rate of drug and polymer release. Both experiments and simulations provided evidence of polymer microstructures and drug-polymer interactions as important factors for the dissolution behavior of the investigated ASDs, consistent with previous work by Pudlas et al. (Eur. J. Pharm. Sci.2015, 67, 21-31). As experimental and simulation results are consistent and complementary, it is clear that there is significant potential for combined experimental and computational research for a detailed understanding of ASD formulations and, hence, formulation optimization.

A unified approach to design controller in cascade control structure for unstable, integrating and stable processes.

This article presents a unified approach of controller design in cascade control structure (CCS) for unstable, integrating and stable processes with dead-time to achieve enhanced load disturbance rejection. The design of inner and outer loop controllers in CCS is based, partially on the direct synthesis approach and partially on the pole placement method. First, the parameters of the inner loop controller are obtained and then the outer loop controller is designed by considering the inner loop as a part of the primary plant. The proposed design approach deals with a wide range of processes having unstable, integrating and stable dynamics in a unified way. It is applied directly on the higher and lower order processes, as the proposed strategy is acquitted from the approximation of the dead-time and model order reduction of the plant. Simulations have been conducted to show the efficacy of the present approach. The results shows that the present approach provides enhanced regulatory performance as compared to the recently reported approaches from the literature.

A deep neural network model for packing density predictions and its application in the study of 1.5 million organic molecules.

The process of developing new compounds and materials is increasingly driven by computational modeling and simulation, which allow us to characterize candidates before pursuing them in the laboratory. One of the non-trivial properties of interest for organic materials is their packing in the bulk, which is highly dependent on their molecular structure. By controlling the latter, we can realize materials with a desired density (as well as other target properties). Molecular dynamics simulations are a popular and reasonably accurate way to compute the bulk density of molecules, however, since these calculations are computationally intensive, they are not a practically viable option for high-throughput screening studies that assess material candidates on a massive scale. In this work, we employ machine learning to develop a data-derived prediction model that is an alternative to physics-based simulations, and we utilize it for the hyperscreening of 1.5 million small organic molecules as well as to gain insights into the relationship between structural makeup and packing density. We also use this study to analyze the learning curve of the employed neural network approach and gain empirical data on the dependence of model performance and training data size, which will inform future investigations.

Benchmarking DFT approaches for the calculation of polarizability inputs for refractive index predictions in organic polymers.

In a previous study, we introduced a new computational protocol to accurately predict the index of refraction (RI) of organic polymers using a combination of first-principles and data modeling. This protocol is based on the Lorentz-Lorenz equation and involves the calculation of static polarizabilities and number densities of oligomer sequences, which are extrapolated to the polymer limit. We chose to compute the polarizabilities within the density functional theory (DFT) framework using the PBE0/def2-TZVP-D3 model chemistry. While this ad hoc choice proved remarkably successful, it is also relatively expensive from a computational perspective. It represents the bottleneck step in the overall RI modeling protocol, thus limiting its utility for virtual high-throughput screening studies, in which efficiency is essential. For polymers that exhibit late-onset extensivity, the employed linear extrapolation scheme can require demanding calculations on long-oligomer sequences, thus becoming another bottleneck. In the work presented here, we benchmark DFT model chemistries to identify approaches that optimize the balance between accuracy and efficiency for this application domain. We compare results for conjugated and non-conjugated polymers, augment our original extrapolation approach with a non-linear option, analyze how the polarizability errors propagate into the RI predictions, and offer guidance for method selection.

Combining first-principles and data modeling for the accurate prediction of the refractive index of organic polymers.

Organic materials with a high index of refraction (RI) are attracting considerable interest due to their potential application in optic and optoelectronic devices. However, most of these applications require an RI value of 1.7 or larger, while typical carbon-based polymers only exhibit values in the range of 1.3-1.5. This paper introduces an efficient computational protocol for the accurate prediction of RI values in polymers to facilitate in silico studies that can guide the discovery and design of next-generation high-RI materials. Our protocol is based on the Lorentz-Lorenz equation and is parametrized by the polarizability and number density values of a given candidate compound. In the proposed scheme, we compute the former using first-principles electronic structure theory and the latter using an approximation based on van der Waals volumes. The critical parameter in the number density approximation is the packing fraction of the bulk polymer, for which we have devised a machine learning model. We demonstrate the performance of the proposed RI protocol by testing its predictions against the experimentally known RI values of 112 optical polymers. Our approach to combine first-principles and data modeling emerges as both a successful and a highly economical path to determining the RI values for a wide range of organic polymers.

EphA2 Expression Regulates Inflammation and Fibroproliferative Remodeling in Atherosclerosis.

BACKGROUND: Atherosclerotic plaque formation results from chronic inflammation and fibroproliferative remodeling in the vascular wall. We previously demonstrated that both human and mouse atherosclerotic plaques show elevated expression of EphA2, a guidance molecule involved in cell-cell interactions and tumorigenesis. METHODS: Here, we assessed the role of EphA2 in atherosclerosis by deleting EphA2 in a mouse model of atherosclerosis (Apoe-/-) and by assessing EphA2 function in multiple vascular cell culture models. After 8 to 16 weeks on a Western diet, male and female mice were assessed for atherosclerotic burden in the large vessels, and plasma lipid levels were analyzed. RESULTS: Despite enhanced weight gain and plasma lipid levels compared with Apoe-/- controls, EphA2-/-Apoe-/- knockout mice show diminished atherosclerotic plaque formation, characterized by reduced proinflammatory gene expression and plaque macrophage content. Although plaque macrophages express EphA2, EphA2 deletion does not affect macrophage phenotype, inflammatory responses, and lipid uptake, and bone marrow chimeras suggest that hematopoietic EphA2 deletion does not affect plaque formation. In contrast, endothelial EphA2 knockdown significantly reduces monocyte firm adhesion under flow. In addition, EphA2-/-Apoe-/- mice show reduced progression to advanced atherosclerotic plaques with diminished smooth muscle and collagen content. Consistent with this phenotype, EphA2 shows enhanced expression after smooth muscle transition to a synthetic phenotype, and EphA2 depletion reduces smooth muscle proliferation, mitogenic signaling, and extracellular matrix deposition both in atherosclerotic plaques and in vascular smooth muscle cells in culture. CONCLUSIONS: Together, these data identify a novel role for EphA2 in atherosclerosis, regulating both plaque inflammation and progression to advanced atherosclerotic lesions. Cell culture studies suggest that endothelial EphA2 contributes to atherosclerotic inflammation by promoting monocyte firm adhesion, whereas smooth muscle EphA2 expression may regulate the progression to advanced atherosclerosis by regulating smooth muscle proliferation and extracellular matrix deposition.

Investigation of Stent Implant Mechanics Using Linear Analytical and Computational Approach.

Stent implants are essential in restoring normal blood flow in atherosclerotic arteries. Recent studies have shown high failure rates of stent implants in superficial femoral artery (SFA) as a result of dynamic loading environment imposed on the stent implants by the diseased arterial wall and turbulent blood flow. There are variety of stent designs and materials currently on the market however, there is no clear understanding if specific stent design is suitable with the material that is manufactured from and if this combination can sustain the life-cycle that the stent implants need to undergo once inside the artery. Lack of studies have been presented that relate stent mechanical properties with stent geometry and material used. This study presents linear theoretical and computational modeling approach that determines stent mechanical properties with effective stiffness of the deployed stent. Effective stiffness of the stent has been accurately derived based on stent structure design and loading in axial and radial directions. A rhombus stent structure was selected for this study due to its more common use and produced by main stream manufacturers. The derived theoretical model was validated using numerical finite element modeling approach. Results from this study can lead to preliminary insight towards understanding of stent deformation based on stent geometry, material properties and artery wall pressure; and how to carefully match stent's geometry with suitable material for long life cycle, increased strength, and reliable performance of stent implants.

Mechanical Properties of High Entropy Alloy Al0.1CoCrFeNi for Peripheral Vascular Stent Application.

High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored. This paper discusses the mechanical behavior and microstructure of Al0.1CoCrFeNi HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rates. Results show that Al0.1CoCrFeNi alloy possesses characteristics that compare well against currently used stent materials and it can potentially find use in peripheral vascular stent implants and extend their life-cycle.

Comparative Assessment of Procedure Cost and Outcomes Between Guidewire and Crossing Device Strategies to Cross Peripheral Artery Chronic Total Occlusions.

OBJECTIVES: The aim of this study was to assess actual procedural costs and outcomes comparing wire-catheter and dedicated chronic total occlusion (CTO) device strategies to cross peripheral artery CTOs. BACKGROUND: Peripheral artery CTO interventions are frequently performed, but there are limited data on actual procedural costs and outcomes comparing wire-catheter and dedicated CTO devices. METHODS: The XLPAD (Excellence in Peripheral Artery Disease Intervention) registry (NCT01904851) was accessed to retrospectively compare cost and 30-day and 12-month outcomes of wire-catheter and crossing device strategies for treatment of infrainguinal peripheral artery CTO. RESULTS: Of all 3,234 treated lesions, 42% (n = 1,362) were CTOs in 1,006 unique patients. Wire-catheter approaches were used in 82% of CTOs, whereas dedicated CTO devices were used in 18% (p < 0.0001). CTO crossing device use was associated with significantly higher technical success (74% vs. 65%; p < 0.0001) and mean procedure cost ($7,800.09 vs. $4,973.24; p < 0.0001). Because 12-month repeat revascularization (11.3% vs. 17.2%; p = 0.02) and amputation rates (2.8% vs. 8.5%; p = 0.002) in the CTO crossing device arm were lower compared with the wire-catheter group, the net cost for an initial CTO crossing device strategy was $423.80 per procedure. CONCLUSIONS: An initial wire-catheter approach to cross a peripheral artery CTO is most frequently adopted. The use of dedicated CTO crossing devices provides significantly higher technical success and lower reintervention and amputation rates, at a net cost of $423.80 per procedure at 12 months.

Safety and Effectiveness of the Nav-6 Filter in Preventing Distal Embolization During Jetstream Atherectomy of Infrainguinal Peripheral Artery Lesions.

BACKGROUND: The risk of distal embolization (DE) during infrainguinal peripheral artery interventions (PAI) is often mitigated by the use of embolic protection devices. There are limited data on the use of filters with the Jetstream (JS) atherectomy device, a rotational cutter with aspiration capacity. The Nav-6 filter is uniquely suited for use with the JS due to its wire compatibility and detachment from the filter; however, data on the off-label use of this combination have not been reported. METHODS: Consecutive patients between October 2008 and April 2015 undergoing endovascular infrainguinal PAI with JS were analyzed as part of the Excellence in Peripheral Artery Disease (XL-PAD) registry (NCT01904851). Patients were divided into two subgroups with Nav-6 filter use vs no filter use. Descriptive and univariate analyses were performed. RESULTS: Among 141 patients (mean age, 67.8 ± 10.8 years; 169 lesions) included in this study, the Nav-6 filter was used in 82 (59%). Use of a filter was more frequent in longer lesions (146 ± 106 mm vs 91 ± 72 mm; P=.01), in more severe stenoses (95% vs 87%; P=.04), and in chronic total occlusions (33% vs 8.3%; P=.01). Patients receiving filters had longer procedure duration (102 ± 51 min vs 66 ± 41 min; P=.01) and longer fluoroscopy times (31 ± 16 min vs 21 ± 10 min; P<.001). Use of the Nav-6 filter with the JS during PAI was associated with numerically lower rates of DE (1.8% vs 8%; P=.10) and similar rates of death and amputation. At 12 months, the target-lesion revascularization rate was higher in the filter group (22% vs 2.7%; P=.02), likely secondary to use of the filter in more complex lesions. CONCLUSION: Nav-6 filter during JS atherectomy was predominantly used during complex infrainguinal PAI and was associated with less occurrence of DE.

JetStream Rotational and Aspiration Atherectomy in Treating In-Stent Restenosis of the Femoropopliteal Arteries: Results of the JETSTREAM-ISR Feasibility Study.

PURPOSE: To evaluate the outcomes and stent-device interaction of the JetStream atherectomy device in the treatment of in-stent restenosis (ISR) of the femoropopliteal segment. METHODS: The JetStream XC atherectomy device, a rotational cutter with aspiration capacity, was evaluated in a prospective cohort of 29 patients (mean age 69.9 ± 11.7 years; 11 men) with femoropopliteal ISR in 32 limbs (ClinicalTrials.gov identifier NCT01722877). Lesion length was 17.4 ± 13.1 cm. The primary effectiveness outcome was acute success (≤ 30% residual narrowing with no serious adverse events). The primary safety endpoint was major adverse events. Secondary endpoints included clinically driven target lesion revascularization (TLR) at 6 months and 1 year and loss of stent integrity as assessed by an angiographic core laboratory. RESULTS: Treated length was 19.5 ± 12.9 cm. Acute success was obtained in 29/32 (91%) limbs. Acute device success (<50% residual narrowing after atherectomy alone) was 76% (22/29). Adjunctive balloon angioplasty was performed in all cases at a mean pressure of 11.6 ± 3.3 atm. Embolic filter protection was used in 16 (50%) of 32 limbs. Macrodebris was noted in 2 (12%) of 16 filters. Distal embolization requiring treatment occurred in 3/32 (9.4%) limbs (2 with no filter). Other non-procedure-related adverse events were 1 (3%) death (nonvascular) and 1 (3%) case of major bleeding. There were no new stent fractures or deformities (n=24) postatherectomy. Follow-up was completed on 27 patients (29 limbs) at 6 and 12 months. TLR at these time points occurred in 4/29 (14%) and 12/29 (41%) patients. Patency (duplex-derived peak systolic velocity ratio <2.4) was 72% at 6 months. CONCLUSION: JetStream atherectomy using the XC device has favorable acute results in treating femoropopliteal ISR with high procedure success, no device-stent interaction, and favorably low TLR rates. A multicenter trial is needed to confirm these results.

Femoropopliteal Artery Stent Thrombosis: Report From the Excellence in Peripheral Artery Disease Registry.

BACKGROUND: There are limited data on femoropopliteal artery stent thrombosis (ST), which is a serious adverse outcome of peripheral artery interventions. METHODS AND RESULTS: Index procedures resulting in femoropopliteal ST were compared with stent procedures without subsequent ST in the Excellence in Peripheral Artery Disease registry. The study data had a total of 724 cases of stent procedures and 604 unique patients. Femoropopliteal ST occurred in 26 of 604 patients (4.3%) over a median follow-up of 6 months post procedure. ST was more likely to occur in men (96.3% versus 82.2%; P=0.026) and to have an initial intervention for chronic total occlusions (88.5% versus 64.0%; P=0.01). There was no significant difference in ST between drug-coated and bare-metal stents (4.4% versus 3.4%; P=0.55), but the rate of ST was significantly higher with self-expanding covered stent grafts compared with bare-metal stents (10.6% versus 3.4%; P=0.02). ST was significantly associated with an increased risk of 12-month major adverse limb events (hazard ratio, 4.99; 95% confidence interval, 2.31-10.77; P<0.001) compared with no ST. On multivariate analysis, treatment of chronic total occlusion lesions (odds ratio, 3.46; 95% confidence interval, 0.98-12.20; P=0.05) and in-stent restenosis lesions (odds ratio, 5.30; 95% confidence interval, 1.83-15.32; P=0.002) were independently associated with an increased risk of ST. CONCLUSIONS: In a multicenter peripheral interventional registry, femoropopliteal ST occurred in 4.3% of patients who underwent stent procedures, and it was associated with treatment of chronic total occlusions and in-stent restenosis lesions, and had higher 12-month major adverse limb events. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01904851.

Determinants of operator and patient radiation exposure during cardiac catheterization: Insights from the RadiCure (RADIation reduction during cardiac catheterization using real-timE monitoring) trial.

BACKGROUND: In the RadiCure study 505 catheterization procedures were 1:1 randomized to use or no use of real-time radiation monitoring. Use of the Bleeper Sv monitor resulted in a significant reduction in operator radiation exposure. METHODS: We examined the association between several baseline and procedural parameters with operator and patient radiation exposure using univariable and multivariable analysis in the 505 patients that were enrolled in RadiCure. All baseline demographic and procedure characteristics recorded were included in the univariable analysis. RESULTS: Median fluoroscopy time was 6.2 (2.5-12.5) minutes, median patient air kerma dose was 0.908 (0.602-1.636) Gray and median first operator exposure was 10 (5-22) µSv. For analysis purposes, the 505 procedures were dichotomized based on the median operator exposure (10 µSv) and median patient radiation dose (0.908 Gray). On multivariable analysis, factors associated with high (above median or >10 µSv) first operator radiation exposure included radial access (odds ratio [OR] 5.44, 95% Confidence Interval [CI] 2.88-10.76), chronic total occlusion (CTO) intervention (OR 12.78, 95% CI 4.42-43.60), real-time radiation monitoring (OR 0.42, 95% CI 0.26-0.66), and use of a radioabsorbent drape (OR 0.53, 95% CI 0.28-0.96). High patient radiation dose (above median or >0.908 Gray) was associated with body mass index>30 kg/m2 (OR 3.22, 95% CI 1.99-5.29), prior MI (OR 2.26, 95% CI 1.29-4.04), prior cerebrovascular disease (OR 0.34, 95% CI 0.15-0.75), hypertension (OR 2.40, 95% CI 1.05-5.82), prior coronary artery bypass graft surgery (OR 2.46, 95% CI 1.40-4.39) and CTO intervention (OR 12.93, 95% CI 3.28-87.31), but was not associated with real-time radiation monitoring and use of a radioabsorbent drape. CONCLUSIONS: Several clinical and procedural factors are associated with higher patient and operator radiation exposure. Real-time radiation monitoring and use of disposable radiation shields were associated with lower operator, but not patient, radiation dose. © 2015 Wiley Periodicals, Inc.

The role of antiplatelet therapy in patients with peripheral artery disease and lower extremity peripheral artery revascularization.

PURPOSE OF REVIEW: Although antiplatelet agents are frequently prescribed to patients with lower extremity peripheral artery disease (PAD), there is an overall lack of consensus among published evidence and guidelines with respect to this practice. RECENT FINDINGS: Antiplatelet agents are prescribed to patients with PAD to reduce both cardiovascular and limb-based events during the follow-up period. A large evidence base supports the use of antiplatelet monotherapy with aspirin or clopidogrel in patients with symptomatic PAD or a history of peripheral artery revascularization. However, antiplatelet monotherapy has not proven beneficial in patients with asymptomatic PAD. Dual antiplatelet therapy has not demonstrated a clear benefit in reducing the risk of cardiovascular events in patients with symptomatic PAD. Its role in reducing the risk of adverse limb events following endovascular or surgical revascularization also remains unclear. Recently, the use of vorapaxar in addition to aspirin and/or clopidogrel has been associated with a significant reduction in the need for repeat revascularization procedures and hospitalization for limb ischemia in patients with established PAD. SUMMARY: Eligible patients with symptomatic PAD or with a history of peripheral artery revascularization should be prescribed antiplatelet monotherapy for secondary prevention of both cardiovascular and limb events, using aspirin, clopidogrel, and/or vorapaxar. Given the significant overlap of PAD and coronary artery disease, the evidence presented in this article may have important implications for management of patients with coronary artery disease.