Sub-Diffraction Correlation of Quantum Emitters and Local Strain Fields in Strain-Engineered WSe2 Monolayers

Strain-engineering in atomically thin metal dichalcogenides is a useful method for realizing single-photon emitters (SPEs) for quantum technologies. Correlating SPE position with local strain topography is challenging due to localization inaccuracies from the diffraction limit. Currently, SPEs are assumed to be positioned at the highest strained location and are typically identified by randomly screening narrow-linewidth emitters, of which only a few are spectrally pure. In this work, hyperspectral quantum emitter localization microscopy is used to locate 33 SPEs in nanoparticle-strained WSe2 monolayers with sub-diffraction-limit resolution (≈30 nm) and correlate their positions with the underlying strain field via image registration. In this system, spectrally pure emitters are not concentrated at the highest strain location due to spectral contamination; instead, isolable SPEs are distributed away from points of peak strain with an average displacement of 240 nm. These observations point toward a need for a change in the design rules for strain-engineered SPEs and constitute a key step toward realizing next-generation quantum optical architectures.

Radiosensitizing Effect of Dextran-Coated Iron Oxide Nanoparticles on Malignant Glioma Cells

The potential of standard methods of radiation therapy is limited by the dose that can be safely delivered to the tumor, which could be too low for radical treatment. The dose efficiency can be increased by using radiosensitizers. In this study, we evaluated the sensitizing potential of biocompatible iron oxide nanoparticles coated with a dextran shell in A172 and Gl-Tr glioblastoma cells in vitro. The cells preincubated with nanoparticles for 24 h were exposed to ionizing radiation (X-ray, gamma, or proton) at doses of 0.5-6 Gy, and their viability was assessed by the Resazurin assay and by staining of the surviving cells with crystal violet. A statistically significant effect of radiosensitization by nanoparticles was observed in both cell lines when cells were exposed to 35 keV X-rays. A weak radiosensitizing effect was found only in the Gl-Tr line for the 1.2 MeV gamma irradiation and there was no radiosensitizing effect in both lines for the 200 MeV proton irradiation at the Bragg peak. A slight (ca. 10%) increase in the formation of additional reactive oxygen species after X-ray irradiation was found when nanoparticles were present. These results suggest that the nanoparticles absorbed by glioma cells can produce a significant radiosensitizing effect, probably due to the action of secondary electrons generated by the magnetite core, whereas the dextran shell of the nanoparticles used in these experiments appears to be rather stable under radiation exposure.

Combination of personalized computational modeling and machine learning for optimization of left ventricular pacing site in cardiac resynchronization therapy

Introduction: The 30-50% non-response rate to cardiac resynchronization therapy (CRT) calls for improved patient selection and optimized pacing lead placement. The study aimed to develop a novel technique using patient-specific cardiac models and machine learning (ML) to predict an optimal left ventricular (LV) pacing site (ML-PS) that maximizes the likelihood of LV ejection fraction (LVEF) improvement in a given CRT candidate. To validate the approach, we evaluated whether the distance D_PS between the clinical LV pacing site (ref-PS) and ML-PS is associated with improved response rate and magnitude. Materials and methods: We reviewed retrospective data for 57 CRT recipients. A positive response was defined as a more than 10% LVEF improvement. Personalized models of ventricular activation and ECG were created from MRI and CT images. The characteristics of ventricular activation during intrinsic rhythm and biventricular (BiV) pacing with ref-PS were derived from the models and used in combination with clinical data to train supervised ML classifiers. The best logistic regression model classified CRT responders with a high accuracy of 0.77 (ROC AUC = 0.84). The LR classifier, model simulations and Bayesian optimization with Gaussian process regression were combined to identify an optimal ML-PS that maximizes the ML-score of CRT response over the LV surface in each patient. Results: The optimal ML-PS improved the ML-score by 17 ± 14% over the ref-PS. Twenty percent of the non-responders were reclassified as positive at ML-PS. Selection of positive patients with a max ML-score >0.5 demonstrated an improved clinical response rate. The distance D_PS was shorter in the responders. The max ML-score and D_PS were found to be strong predictors of CRT response (ROC AUC = 0.85). In the group with max ML-score > 0.5 and D_PS< 30 mm, the response rate was 83% compared to 14% in the rest of the cohort. LVEF improvement in this group was higher than in the other patients (16 ± 8% vs. 7 ± 8%). Conclusion: A new technique combining clinical data, personalized heart modelling and supervised ML demonstrates the potential for use in clinical practice to assist in optimizing patient selection and predicting optimal LV pacing lead position in HF candidates for CRT.

Current State and Prospectives for Proton Boron Capture Therapy

The development of new methods increasing the biological effectiveness of proton therapy (PT) is of high interest in radiation oncology. The use of binary technologies, in which the damaging effect of proton radiation is further enhanced by the selective accumulation of the radiosensitizer in the target tissue, can significantly increase the effectiveness of radiation therapy. To increase the absorbed dose in a tumor target, proton boron capture therapy (PBCT) was proposed based on the reaction of proton capture on the ¹¹B isotope with the formation of three α-particles. This review summarizes data on theoretical and experimental studies on the effectiveness and prospects of proton boron capture therapy.

Chemomechanical modification of quantum emission in monolayer WSe2

Two-dimensional (2D) materials have attracted attention for quantum information science due to their ability to host single-photon emitters (SPEs). Although the properties of atomically thin materials are highly sensitive to surface modification, chemical functionalization remains unexplored in the design and control of 2D material SPEs. Here, we report a chemomechanical approach to modify SPEs in monolayer WSe₂ through the synergistic combination of localized mechanical strain and noncovalent surface functionalization with aryl diazonium chemistry. Following the deposition of an aryl oligomer adlayer, the spectrally complex defect-related emission of strained monolayer WSe₂ is simplified into spectrally isolated SPEs with high single-photon purity. Density functional theory calculations reveal energetic alignment between WSe₂ defect states and adsorbed aryl oligomer energy levels, thus providing insight into the observed chemomechanically modified quantum emission. By revealing conditions under which chemical functionalization tunes SPEs, this work broadens the parameter space for controlling quantum emission in 2D materials.

Quantitative Characterization of the Anisotropic Thermal Properties of Encapsulated Two-Dimensional MoS2 Nanofilms

Two-dimensional (2D) semiconductors exhibit unique physical properties at the limit of a few atomic layers that are desirable for optoelectronic, spintronic, and electronic applications. Some of these materials require ambient encapsulation to preserve their properties from environmental degradation. While encapsulating 2D semiconductors is essential to device functionality, they also impact heat management due to the reduced thermal conductivity of the 2D material. There are limited experimental reports on in-plane thermal conductivity measurements in encapsulated 2D semiconductors. These measurements are particularly challenging in ultrathin films with a lower thermal conductivity than graphene since it may be difficult to separate the thermal effects of the sample from the encapsulating layers. To address this challenge, we integrated the frequency domain thermoreflectance (FDTR) and optothermal Raman spectroscopy (OTRS) techniques in the same experimental platform. First, we use the FDTR technique to characterize the cross-plane thermal conductivity and thermal boundary conductance. Next, we measure the in-plane thermal conductivity by model-based analysis of the OTRS measurements, using the cross-plane properties obtained from the FDTR measurements as input parameters. We provide experimental data for the first time on the thickness-dependent in-plane thermal conductivity of ultrathin MoS2 nanofilms encapsulated by alumina (Al2O3) and silica (SiO2) thin films. The measured thermal conductivity increased from 26.0 ± 10.0 W m-1 K-1 for monolayer MoS2 to 39.8 ± 10.8 W m-1 K-1 for the six-layer films. We also show that the thickness-dependent cross-plane thermal boundary conductance of the Al2O3/MoS2/SiO2 interface is limited by the low thermal conductance (18.5 MW m-2 K-1) of the MoS2/SiO2 interface, which has important implications on heat management in SiO2-supported and encased MoS2 devices. The measurement methods can be generalized to other 2D materials to study their anisotropic thermal properties.

Conversion of Classical Light Emission from a Nanoparticle-Strained WSe2 Monolayer into Quantum Light Emission via Electron Beam Irradiation

Solid-state single photon emitters (SPEs) within atomically thin transition metal dichalcogenides (TMDs) have recently attracted interest as scalable quantum light sources for quantum photonic technologies. Among TMDs, WSe₂ monolayers (MLs) are promising for the deterministic fabrication and engineering of SPEs using local strain fields. The ability to reliably produce isolatable SPEs in WSe₂ is currently impeded by the presence of numerous spectrally overlapping states that occur at strained locations. Here nanoparticle (NP) arrays with precisely defined positions and sizes are employed to deterministically create strain fields in WSe₂ MLs, thus enabling the systematic investigation and control of SPE formation. Using this platform, electron beam irradiation at NP-strained locations transforms spectrally overlapped sub-bandgap emission states into isolatable, anti-bunched quantum emitters. The dependence of the emission spectra of WSe₂ MLs as a function of strain magnitude and exposure time to electron beam irradiation is quantified and provides insight into the mechanism for SPE production. Excitons selectively funnel through strongly coupled sub-bandgap states introduced by electron beam irradiation, which suppresses spectrally overlapping emission pathways and leads to measurable anti-bunched behavior. The findings provide a strategy to generate isolatable SPEs in 2D materials with a well-defined energy range.

Experimental validation of proton boron capture therapy for glioma cells

Proton boron capture therapy (PBCT) has emerged from particle acceleration research for enhancing the biological effectiveness of proton therapy. The mechanism responsible for the dose increase was supposed to be related to proton-boron fusion reactions (¹¹B + p → 3α + 8.7 MeV). There has been some experimental evidence that the biological efficiency of protons is significantly higher for boron-11-containing prostate or breast cancer cells. The aim of this study was to evaluate the sensitizing potential of sodium borocaptate (BSH) under proton irradiation at the Bragg peak of cultured glioma cells. To address this problem, cells of two glioma lines were preincubated with 80 or 160 ppm boron-11, irradiated both at the middle of 200 MeV beam Spread-Out Bragg Peak (SOBP) and at the distal end of the 89.7 MeV beam SOBP and assessed for the viability, as well as their ability to form colonies. Our results clearly show that BSH provides for only a slight, if any, enhancement of the effect of proton radiation on the glioma cells in vitro. In addition, we repeated the experiments using the Du145 prostate cancer cell line, for which an increase in the biological efficiency of proton irradiation in the presence of sodium borocaptate was demonstrated previously. The data presented add new argument against the efficiency of proton boron capture therapy when based solely on direct dose-enhancement effect by the proton capture nuclear reaction, underlining the need to investigate the indirect effects of the secondary alpha irradiation depending on the state and treatment conditions of the irradiated tissue.

Liquid-Phase Exfoliation of Magnetically and Optoelectronically Active Ruthenium Trichloride Nanosheets

α-RuCl₃ is a layered transition metal halide that possesses a range of exotic magnetic, optical, and electronic properties including fractional excitations indicative of a proximate Kitaev quantum spin liquid (QSL). While previous reports have explored these properties on idealized single crystals or mechanically exfoliated samples, the scalable production of α-RuCl₃ nanosheets has not yet been demonstrated. Here, we perform liquid-phase exfoliation (LPE) of α-RuCl₃ through an electrochemically assisted approach, which yields ultrathin, electron-doped α-RuCl₃ nanosheets that are then assembled into electrically conductive large-area thin films. The crystalline integrity of the α-RuCl₃ nanosheets following LPE is confirmed through a wide range of structural and chemical analyses. Moreover, the physical properties of the LPE α-RuCl₃ nanosheets are investigated through electrical, optical, and magnetic characterization methods, which reveal a structural phase transition at 230 K that is consistent with the onset of Kitaev paramagnetism in addition to an antiferromagnetic transition at 2.6 K. Intercalated ions from the electrochemical LPE protocol favorably alter the optical response of the α-RuCl₃ nanosheets, enabling large-area Mott insulator photodetectors that operate at telecommunications-relevant infrared wavelengths near 1.55 μm. These photodetectors show a linear photocurrent response as a function of incident power, which suggests negligible trap-mediated recombination or photothermal effects, ultimately resulting in a photoresponsivity of ≈2 mA/W.

Morphotaxy of Layered van der Waals Materials

Layered van der Waals (vdW) materials have attracted significant attention due to their materials properties that can enhance diverse applications including next-generation computing, biomedical devices, and energy conversion and storage technologies. This class of materials is typically studied in the two-dimensional (2D) limit by growing them directly on bulk substrates or exfoliating them from parent layered crystals to obtain single or few layers that preserve the original bonding. However, these vdW materials can also function as a platform for obtaining additional phases of matter at the nanoscale. Here, we introduce and review a synthesis paradigm, morphotaxy, where low-dimensional materials are realized by using the shape of an initial nanoscale precursor to template growth or chemical conversion. Using morphotaxy, diverse non-vdW materials such as HfO₂ or InF₃ can be synthesized in ultrathin form by changing the composition but preserving the shape of the original 2D layered material. Morphotaxy can also enable diverse atomically precise heterojunctions and other exotic structures such as Janus materials. Using this morphotaxial approach, the family of low-dimensional materials can be substantially expanded, thus creating vast possibilities for future fundamental studies and applied technologies.

Machine Learning Prediction of Cardiac Resynchronisation Therapy Response From Combination of Clinical and Model-Driven Data

Background: Up to 30–50% of chronic heart failure patients who underwent cardiac resynchronization therapy (CRT) do not respond to the treatment. Therefore, patient stratification for CRT and optimization of CRT device settings remain a challenge.

Objective: The main goal of our study is to develop a predictive model of CRT outcome using a combination of clinical data recorded in patients before CRT and simulations of the response to biventricular (BiV) pacing in personalized computational models of the cardiac electrophysiology.

Materials and Methods: Retrospective data from 57 patients who underwent CRT device implantation was utilized. Positive response to CRT was defined by a 10% increase in the left ventricular ejection fraction in a year after implantation. For each patient, an anatomical model of the heart and torso was reconstructed from MRI and CT images and tailored to ECG recorded in the participant. The models were used to compute ventricular activation time, ECG duration and electrical dyssynchrony indices during intrinsic rhythm and BiV pacing from the sites of implanted leads. For building a predictive model of CRT response, we used clinical data recorded before CRT device implantation together with model-derived biomarkers of ventricular excitation in the left bundle branch block mode of activation and under BiV stimulation. Several Machine Learning (ML) classifiers and feature selection algorithms were tested on the hybrid dataset, and the quality of predictors was assessed using the area under receiver operating curve (ROC AUC). The classifiers on the hybrid data were compared with ML models built on clinical data only.

Results: The best ML classifier utilizing a hybrid set of clinical and model-driven data demonstrated ROC AUC of 0.82, an accuracy of 0.82, sensitivity of 0.85, and specificity of 0.78, improving quality over that of ML predictors built on clinical data from much larger datasets by more than 0.1. Distance from the LV pacing site to the post-infarction zone and ventricular activation characteristics under BiV pacing were shown as the most relevant model-driven features for CRT response classification.

Conclusion: Our results suggest that combination of clinical and model-driven data increases the accuracy of classification models for CRT outcomes.

Fiber-optic laser energy for pulmonary artery denervation: results of an experimental study

Background/Introduction

Pulmonary artery denervation (PADN) is an interventional procedure aiming to modulate and correct pulmonary artery (PA) pressure. New technologies and energy sources are being tested currently. However, the effects of laser energy on the PA wall are unknown.

Purpose

To assess the acute effects and impact of laser energy for PADN procedure in normotensive sheep by applying different power settings and session times.

Methods

A total of 10 normotensive Katumsky sheep were included in the experiment. Percutaneous vascular access was performed under general anesthesia. A fiberoptic open-irrigated non-steerable catheter was introduced via a femoral vein through a steerable sheath. Laser applications were applied in the PA trunk and the proximal areas of the right and left PA under fluoroscopic guidance with a 5mm distance between points in the anterior, posterior and lateral walls. Applications were delivered with power 10–30W, 10–35s in duration; irrigation flow 40ml/min. After the procedure, experimental animals were euthanized and underwent an autopsy. PA samples were obtained regardless of the absence of visible laser-related lesions for histological analysis (hematoxylin staining) and immunohistochemical labelling (S100).

Results

A total of 108 ablation sessions were performed, 33 in the right PA, 30 in the left PA and 42 in the PA trunk. During macroscopic examination, laser-related lesions described as irregular brown hemorrhage spots and rough defects observed in the PA endothelium were not homogenous in all experimental animals. Thermal injuries either in the left or right lung lobes were identified in 5 (50%) experimental animals when using 30W during 10–20sec. In 5 (50%) sheep no collateral lung injuries were identified when using 10–20W from 20–35s. A total of 64 PA fragments underwent microscopic examination, acute thermal tissue lesions were observed in all experimental animals despite the absence of laser-related lesions in the PA endothelium; dissection, edema, disruption trough tunica layers, hemorrhage and necrosis at different depth walls. The most frequent nerve damage was obtained with 20W ablation: 5/8 PAs vs, 1/6 with 10–15W and 1/14 with 25–30W (P=0.01). At the same time, there was no difference in intima necrosis between the groups (1/6, 2/8 and 4/14 for 10–15, 20 and 25–30W groups, respectively).

Conclusion(s)

Percutaneous PA laser ablation is feasible, reduction of perivascular nerve expression is seen most frequently, when 20W/20–35 s ablation is performed. PA lesions may differ in depth and characteristics, and perivascular nerve damage might be seen in cases with preserved intima.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant of the Ministry of Science and Higher Education of the Russian Federation

Pulmonary artery radiofrequency ablation in an acute porcine model of pulmonary arterial hypertension

Introduction

Pulmonary hemodynamics improvement after pulmonary artery denervation (PADN) was demonstrated in PAH. Questions arise regarding PADN perioperative effectiveness and the accuracy of the target nerves damage. The aim of the study was to evaluate whether PADN decreases pulmonary artery pressure (PAP) in acute thromboxane A2 (U46619)–induced PAH, and damages PA perivascular nerve fibers.

Materials and methods

10 male Landrace swine (34.7±5.1 kg). In 6 swine acute reversible target mean PAP of 40 mm Hg was induced with synthetic thromboxane A2 infusion (U46619). Control group: 4 swine with PADN. Hemodynamics was assessed throughout the study, PAH modeling was done before and 20 min after PADN (radiofrequency energy, 40 Watts), followed by pathology and immunohistochemical studies.

Results

The mean number of RF applications was 17.5±3.6. Pulmonary embolism (PE) was observed after PADN in 3 swine with U46619 infusion, which were excluded. There was no differences in mPAP, PVR and U46619 dosage after PADN in PAH model (12.3±3.5 vs 12.1±1 mm Hg, p=0.2; 150.4±48.7 vs 129.2±64.1 dynes s cm–5; p=0.2; 24.9±3.3 vs 22.4±4.1 mcg; p=0.18; respectively). Similar hemodynamic results were observed in the control group after PADN (mPAP; p=0.3; PVR; p=0.58). S100 expression was evident in the majority of RFA PA species and in some species loss in tyrosine hydroxylase and M1 acetylcholine receptors expression was detected with no hemodynamic correlation.

Conclusions

PADN using an electrophysiological catheter with unipolar energy does not lead to an acute PA perivascular nerve fibers destruction and detectable mPAP changes in U46619-induced PAH. Delayed nerve damage might be attributable to PADN effects observed in previous studies.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant from the Ministry of Science and Higher Education of the Russian Federation (agreement #075-15-2020-800).

Predicting CRT outcome by combining markers from personalized ventricular models of electrophysiology and clinical data

Introduction

Up to 30% of chronic heart failure (CHF) patients undergoing cardiac resynchronization therapy (CRT) do not respond to the treatment. Low CRT response can be associated with incorrect pacing lead positioning in ventricles and not accounting for individual structural changes in myocardium. Therefore, patient stratification for CRT, operation planning and optimization of CRT device settings remain a challenge.

Purpose

In this study, we develop a predictive model of CRT outcomes based on a combination of clinical data recorded in patients before CRT and on simulations of the response to biventricular pacing in personalized computational models of the ventricles.

Methods

We used retrospective data from 27 CHF patients who underwent CRT device implantation. CRT responders were defined using clinical data in a year after therapy as showing a decrease in the end-systolic volume of the left ventricle (LV) and an increase in the ejection fraction. For each patient, an anatomical model of the heart and torso was reconstructed from CT images and used to compute ventricular activation and ECGs without pacing and under bi-ventricular pacing with various locations of stimulating leads. For building a predictive model of patient response to CRT, we used clinical data before CRT (12 features in total per patient) together with model-derived biomarkers under biventricular pacing with clinical lead position (16 features in total per a model). Using nested stratified cross-validation, logistic regression models were fitted to various combinations of datasets.

Results

The best classifier using a complete set of clinical and simulation data showed an average accuracy = 0.78, ROC AUC = 0.78, sensitivity = 0.75, specificity = 0.8, that were much higher than in the model built on the clinical data only. When the best model was fitted to all data on biventricular pacing with clinical lead position, all ten clinical non-responders were truly classified by the model (Fig. 1, left). Using simulations with optimal lead location as input data for this model, seven out of the ten patients were predicted as responders (Fig. 1, right). Blue and orange colours indicate clinical responders and non-responders. Red circles and numbers mark some clinical non-responding patients that are predicted as responders using optimal TAT values.

Conclusion

Our pilot results show that combination of clinical and simulation data significantly increases the accuracy of classification models for CRT outcomes. Our results suggest that model predictions on the optimal ventricular lead location may essentially increase the probability of CRT success.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Russian Science Foundation Figure 1

Evaluation of relationship between interlead electrical delay time and reverse remodeling of left ventricle in patients with quadripolar cardiac resynchronization therapy for long-term follow-up

Background

Cardiac resynchronization therapy (CRT) has undoubtedly shown a high role in the treatment of advanced heart failure (HF). The effectiveness of CRT is individual and variable in each case. It is associated with the functional and structural features of heart as well as the dynamics of these features over time. Despite the quadripolar left ventricle (LV) lead widespread use, the problem of low response to CRT in the early and long-term remains actual. The search for predictors of the CRT response is an important scientific and practical issue.

Purpose

To determine the relationship between the interlead electrical delay time and the CRT response during 24 month postoperative period.

Materials and methods

We evaluated the clinical status, the quality of life and echocardiographic response of 37 patients with HF treated for 2 years with quadripolar LV lead CRT devices implanted according to guidelines: 25 males/12 females with age 62±10 years, 25 pts with history of ischemic cardiac disease, LVEF 26±7%; QRS duration 184±31 ms. The response to CRT was defined as 15% decrease of LV end-systolic volume (ESV). Interlead electrical delay time (EDT) was calculated automatically during CRT implantation, and subsequent 3–6-12–18–24 month follow-up.

Results

The dynamic changes EDT and ESV were assessed for 24 months after CRT. There was a significantly higher average percentage of decrease of ESV in patients (n=18), in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT, in 3 months (12±8% versus 10±6% p=0.021) and in 6 months (23±9% versus 18±9% p=0.003) after CRT. That was the dynamic of reverse remodeling is significantly higher in such patients for the first 6 months.

Using logistic regression, it was shown that the relative decrease EDT in the first 3 months after CRT can be a predictor of outcomes in18 and 24 months after CRT with an accuracy of 71% and 77%, respectively. The greater the relative decrease EDT between 0 and 3 months, the greater the probability of a respond in 18 and 24 months after CRT. The cut-off threshold for determining the outcomes in 18 months was 18% on the balance of specificity and sensitivity equal to 80% and in 24 months was 15% on the balance of specificity and sensitivity equal to 90%.

There were no differences between the HF etiology (ischemic/ non-ischemic) and baseline rhythm.

Conclusion

The relationship between EDT and LV reverse remodeling have been investigated for 24 months. The rate of reverse remodeling is higher in patients in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT. Relative decrease EDT in early period after CRT may be a predictor of the CRT outcomes in longtime period.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Russian Science Foundation

Ongoing antiarrhythmic drug therapy type does not affect the rate of first-pass pulmonary vein isolation: data from a multicenter registry

Background

It is well-known that antiarrhythmic drugs (AAD) change the electrophysiological properties of the atrium mostly by increasing the atrial refractory period and wavelength for reentry. Frequently, atrial fibrillation (AF) catheter ablation is being performed with AAD interruption. However, the information on the impact of AAD on AF ablation performance is lacking, and AAD interruption is not desirable in highly symptomatic patients with persistent arrhythmia.

Purpose

We sought to study potential differences in achieving first-pass pulmonary vein isolation (FPI) during AF ablation in patients receiving different classes of ongoing AADs.

Methods

This was a prospective observational multicenter registry. All centers were invited to participate in the registry voluntarily. Data on demographic, clinical, and procedure characteristics were derived from a web-based system. All catheter ablation procedures were performed according to local practices. A total of 450 patients were enrolled, 408 of them underwent first-time AF ablation. Data on AAD characteristics were available in 350 patients (mean age 61±9 years, 195 (56%) males, 270 (77%) had paroxysmal AF). All patients were divided into three groups: ongoing I class AAD treatment (propafenone, ethacyzin, allapinin, n=76), ongoing II class AAD (beta-blockers, n=60), and ongoing III class AAD (amiodarone, sotalol, n=214).

Results

Baseline clinical and procedural characteristics between AAD groups are summarized in Table. Patients in the I class AAD group were younger, likely had paroxysmal AF, and a smaller mean left atrial diameter. Procedures in the III class AAD group were performed with a higher median target ablation index on the posterior left atrial wall. But the percentage of first-pass isolation was distributed equally between groups (60%, 68%, 61%, p=0.56). The correlation matrix revealed no significant associations between FPI and clinical and procedural variables (r=0.02–0.09; p&gt;0.05 for all).

Conclusion(s)

Our real-life multicenter data demonstrate no difference in FPI achievement between patients receiving different AADs. We suggest that highly symptomatic patients may continue pharmacological treatment during AF ablation without compromising acute ablation success.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Science and Higher Education grant (Russian Federation President Grant) Table 1. Clinical and procedural parameter

Outcome and clinical profile of patients with newly detected atrial fibrillation and cardioembolic stroke

Background

Atrial fibrillation (AF) is a global health care problem with evidence suggesting an increasing prevalence and incidence worldwide. Undiagnosed AF represents the most common cause of thromboembolic events. The aim of the study was to analyze the clinical profile and outcome in patients with cardioembolic stroke and newly detected AF.

Methods

We enrolled 139 consecutive patients with atrial fibrillation and confirmed diagnosis of ischemic stroke (mean age 72.25±6.33 years, 59 male). Follow-up period was 1 year since the episode of acute stroke.

Results

All patients with verified cardioembolic stroke were first diagnosed with AF on admission. Patients with AF were characterized by polymorbidity (hypertension was diagnosed in 96 patients, a concomitant chronic renal failure was observed in 60 cases while a complicated course of coronary heart disease – in 35 patients, 22 patients were diagnosed with diabetes mellitus, while 9 people had a long smoking history). Mean value of CHA2DS2-VASc score was 4.51±1.2 and after acute stroke patients were recommended permanent anticoaugulation (12% – warfarin, 45% – rivaroxaban, 24% – apixaban and 19% – dabigatran). At the end of the year of follow-up patients were taking oral anticoagulants only in 16.2% of cases. In the same time only 9.9% of patients had a history of mild or moderate nasal or gingival bleeding (8.2%) while severe hemorrages were not reported. On multivariable analysis, lack of antithrombotic treatment guideline adherence was associated with increased risk of recurrent stroke (hazard ratio, 4.45; 95% confidence interval, 1.25–6.87; P=0.012 for undertreatment). For 3 (2.2%) patients the recurrent sroke was fatal and 2 (1.4%) patients had lethal outcome due to heart failure deterioration after 6 months of follow up. During one year follow up 27 (19.4%) patients had spontaneous AF conversion into sinus rhythm and 19 (13.7%) patients underwent successful catheter ablation. The adjusted risk of reccurent stroke for those in chronic AF was higher than in sinus rhythm (hazard ratio, 1.70; 95% CI, 1.37–2.12).

Conclusions

This study showed that patients with newly dignosed AF and cardioembolic stroke are characterized with polymorbidity and high thromboembolic risk but after sinus rhythm restoration the adjusted risk of reccurent stroke is much lower. The results demonstrate a low quality care of patients with AF and cardioembolic stroke at the outpatient stage. Appropriate medication compliance is crucial for positive outcomes as well as effectivesecondary stroke prevention in AF patients.

Funding Acknowledgement

Type of funding sources: None.

Ambient-Stable Two-Dimensional CrI3 via Organic-Inorganic Encapsulation

Two-dimensional transitional metal halides have recently attracted significant attention due to their thickness-dependent and electrostatically tunable magnetic properties. However, this class of materials is highly reactive chemically, which leads to irreversible degradation and catastrophic dissolution within seconds in ambient conditions, severely limiting subsequent characterization, processing, and applications. Here, we impart long-term ambient stability to the prototypical transition metal halide CrI₃ by assembling a noncovalent organic buffer layer, perylenetetracarboxylic dianhydride (PTCDA), which templates subsequent atomic layer deposition (ALD) of alumina. X-ray photoelectron spectroscopy demonstrates the necessity of the noncovalent organic buffer layer since the CrI₃ undergoes deleterious surface reactions with the ALD precursors in the absence of PTCDA. This organic-inorganic encapsulation scheme preserves the long-range magnetic ordering in CrI₃ down to the monolayer limit as confirmed by magneto-optical Kerr effect measurements. Furthermore, we demonstrate field-effect transistors, photodetectors, and optothermal measurements of CrI₃ thermal conductivity in ambient conditions.

ECG wearable rhythm monitoring in covid-19 patients

Funding Acknowledgements

Type of funding sources: None.

Background

Wearable monitors and external smart-phone enabled devices represent the new era in remote patient management during covid-19 pandemy. There is growing evidence showing that arrhythmias are one of the major complications of SARS-CoV-2 infection especially in high risk group of patients. 

Methods

We enrolled 34consecutive patients with confirmed diagnosis of SARS-CoV-2 (mean age62.45 ± 5.25years, 16male). Remote wireless rhythm monitoring was performed using portative ECG sensor.Average follow-up period was 21 days during in-hospital stage and 2 months after discharge.

Results

Among hospitalized patients with verified SARS-CoV-2 some presented different arrhytmias before admission (9 patients had atrial fibrillation and 11 patients had history of ventricular extrasystoles and non-sustained ventricular tachycardia). One patient underwent cardiac transplantation 1.5 years ago (female 38 years old with a history of dilated cardiomyopathy) and one patient had implanted CRTD device as primary prevention (male 54 years old with a history of myocardial infarction and low LVEF 28%). Other 12 patients did not experience any cardiac arrhythmias before admission. During monitoring period one patient demonstrated asymptomatic pauses longer than 6 seconds (Figure 1) revealed by portative device. After 2 months of follow up he continued to have hemodinamycally significant rhythm pauses and underwent pacemaker implantation. One patient had spontaneus AF conversion into sinus rhythm (Figure 2) also confirmed by wireless monitoring. Other patients did not demonstrate clinically significant arrhythmias. The duration of QT interval was also monitored during in-hospital period in all patients, average score was 451 ± 12 msec.

Conclusions

Using of wearable electronic devices may contribute to better monitoring of the state of patients and control of symptoms. Abstract Figure. Hemodynamically significant rhythm pause

The prognostic significance of cardiac sympathetic activity and dyssynchrony in cardiac resynchronization therapy in ischemic and non-ischemic heart failure patients

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Russian Foundation for Basic Research

Introduction

Impaired cardiac sympathetic activity and contractility are associated with poor prognosis in patients with heart failure after cardiac resynchronization therapy (CRT). There are few prognostic data of the cardiac sympathetic activity and dyssynchrony in patients with chronic heart failure of various etiologies.

Purpose

To examine the prognostic significance of scintigraphic cardiac sympathetic activity and contractility in predicting the response to CRT and to assess the differences between patients with ischemic (IHF) and non-ischemic (NIHF) heart failure.

Methods

This study included 38 heart failure patients (24 male; mean age of 56 ± 11 years; 16 patients with ischemic etiology), who were submitted to CRT. Before CRT all patients underwent 123I-metaiodobenzylguanidine (123I-MIBG) imaging for cardiac sympathetic activity evaluating: early and delay heart to mediastinum ratio (eH/M and dH/M), summed MIBG Score (eSMS and dSMS). Moreover all patients underwent gated SPECT with the assessments of left ventricle dyssynchrony indexes: standard deviation (SD) and histogram bandwidth (HBW). In addition, all patients underwent gated blood-pool SPECT (GBPS) to assessed ejection fraction (EF) and stroke volume (SV) of both ventricles.

Results

One year after CRT response defined as LV ESV decreased by≥15% and/or LV EF increase by≥5%. Baseline cardiac sympathetic activity parameters showed significant differences between responders and non-responders only in NIHF patients: eH/M: 2.27 (2.02–2.41) vs. 1.64 (1.32–2.16); dH/M: 2.18 (2.11–2.19) vs. 1.45 (1.23 – 1.61); eSMS: 7 (5-7) vs. 15.5 (10–28.5); dSMS: 10 (10–13) vs. 16.5 (15.5–29). Significant differences in baseline LV dyssynchrony indexes between responders and non-responders were in patients of both group: in NIHF patients - SD: 54.3 (43–58) degree vs. 65 (62–66) degree; HBW: 179.5 (140–198) degree vs. 211 (208-213) degree, p &lt; 0.054 in IHF patients - HBW: 162 (115.2–180) degree vs.  115.2 (79.2–136.8) degree. Contractility of RV was significantly differed between responders and non-responders in IHF patients: RV EF: 54.5 (41-56) % vs. 44.5 (37–49.5) %; RV SV: 80 (69-101) ml vs. 55.5 (50–72.5) ml. According to univariate logistic regression analyses in IHF patients LV dyssynchrony indexes – SD (OR = 1.55; 95% CI 1.09-2.2; p &lt; 0.5) and HBW (OR = 1.13; 95% CI 1.02-1.24; p &lt; 0.5), as well as RV indexes – RV EF (OR = 1.11; 95% CI 1.001-1.23; p &lt; 0.5), RV SV (OR = 1.07; 95% CI 1.003-1.138; p &lt; 0.5) were predictors of CRT response. In the group of NIHF patients, dH/M (OR = 1.47; 95% CI 1.08-2; p &lt; 0.5), SD (OR = 0.83; 95% CI 0.73-0.95; p &lt; 0.5), HBW (OR = 0.96; 95% CI 0.93-0.99; p &lt; 0.5) showed the predictive value in terms of CRT response.

Conclusion

 Scintigraphic methods can be used to select patients for CRT. Cardiac 123I-MIBG scintigraphy and gated SPECT may be used for predicting CRT response in NIHF patients. Whereas in IHF patients ECG-gated SPECT and GBPS may be valuable for predicting the response to CRT.

Polymorphism in Post-Dichalcogenide Two-Dimensional Materials

Two-dimensional (2D) materials exhibit a wide range of atomic structures, compositions, and associated versatility of properties. Furthermore, for a given composition, a variety of different crystal structures (i.e., polymorphs) can be observed. Polymorphism in 2D materials presents a fertile landscape for designing novel architectures and imparting new functionalities. The objective of this Review is to identify the polymorphs of emerging 2D materials, describe their polymorph-dependent properties, and outline methods used for polymorph control. Since traditional 2D materials (e.g., graphene, hexagonal boron nitride, and transition metal dichalcogenides) have already been studied extensively, the focus here is on polymorphism in post-dichalcogenide 2D materials including group III, IV, and V elemental 2D materials, layered group III, IV, and V metal chalcogenides, and 2D transition metal halides. In addition to providing a comprehensive survey of recent experimental and theoretical literature, this Review identifies the most promising opportunities for future research including how 2D polymorph engineering can provide a pathway to materials by design.

RBM20-Associated Ventricular Arrhythmias in a Patient with Structurally Normal Heart

RBM20 (RNA-binding motif protein 20) is a splicing factor targeting multiple cardiac genes, and its mutations cause cardiomyopathies. Originally, RBM20 mutations were discovered to cause the development of dilated cardiomyopathy by erroneous splicing of the gene TTN (titin). Titin is a giant protein found in a structure of the sarcomere that functions as a molecular spring and provides a passive stiffness to the cardiomyocyte. Later, RBM20 mutations were also described in association with arrhythmogenic right ventricular cardiomyopathy and left ventricular noncompaction cardiomyopathy. Here, we present a clinical case of a rare arrhythmogenic phenotype and no structural cardiac abnormalities associated with a RBM20 genetic variant of uncertain significance.

Electrical stimulation mapping of the pulmonary artery in swine: impact on pulmonary artery denervation procedure for pulmonary hypertension

Introduction

Pulmonary artery denervation (PAD) has been recently shown to decrease pulmonary artery (PA) pressure. However, there is a lack of data related to target sites for ablation.

Purpose

To determine the optimal PA ablation sites based on response to high-frequency stimulation mapping and anatomical areas where radiofrequency ablation (RFA) should be avoided due to the risk of severe collateral damage.

Methods

A total of 17 Landrace swines were included into the study. PA angiography, hemodynamic measurements by right heart-sided catheterization and electrophysiological mapping (EM) using low (cycle length 330 ms) and high-frequency (33Hz) stimulation (HFS). Stimulation was performed at PA bifurcation and proximal parts of the main PA branches with a 5-mm distance between points; catheter manipulation was performed under fluoroscopic guidance in multiple projections. Points with evoked reactions were tagged on a 3-dimentional PA model in each case. In order to confirm reproducibility of reactions, HFS was performed at least twice at each point with a response. PA models obtained from all animals were combined in one for the final analysis. RFA using an open-irrigated catheter (40 Watts; 40 s; irrigation 30 ml/min) were performed at sites with evoked reactions. Repeated HFS was performed at ablation sites. After the procedure all animals were euthanized and underwent an autopsy study.

Results

Low-frequency stimulation (LFS) allowed to define areas of ventricular capture (VC) where HFS was avoided due to ventricular fibrillation induction risk. During HFS the following evoked responses were documented: sinus bradycardia, sinus rhythm (SR) acceleration, phrenic nerve capture (PNC), and laryngeal recurrent nerve capture. HFS captured left and right phrenic nerves in all animals at PA trunk, and its course was tagged (Figure 1). Laryngeal recurrent nerve capture was found in 4 (23%) of animals. Atrial capture was found in all cases while LFS at the anterior aspects of both PAs even at low output, and this precluded evaluation of neural autonomic reactions in these areas. Evoked bradycardia and SR acceleration were both found during HFS in 10 (59%) of cases each. Following RFA application evoked reactions were non-reproducible in all cases. RFA was applied in areas where no PNC or VC points were observed. An autopsy study confirmed the presence of RF-induced lesions of the PA wall.

Conclusions

There are two important findings of our study. First, stimulation-guided PA mapping is feasible and reveals several specific responses to HFS. Ablation at points with responses leads to non-reproducibility of the evoked reactions, confirming that transcatheter RFA may be an adequate approach for PA denervation. Second, previously proposed circular PA ablation might be associated with phrenic and laryngeal recurrent nerve damage. Stimulation-guided PA denervation can be proposed as a safer procedure, and should be evaluated in clinical settings.

Figure 1. PA schematic representation

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Russian Foundation for Basic Research

Real life experience with atrial fibrillation cryoballoon ablation: results from a nationwide registry

 

Cryoballoon ablation (CBA) is an effective strategy for AF management. The Russian Cryoballoon Atrial Fibrillation Ablation Registry (NCT03040037) is a prospective observational multicenter national registry that aims to provide real-world efficacy, safety and outcomes of this technology.

Purpose

To evaluate the CBA efficacy, types of adverse events following CBA based on a multicenter nationwide registry.

Materials and methods

A web-based registry platform was developed for prospective data entry. The platform consisted of 8 sections: AF ablation experience, patient and CBA characteristics, periprocedural management, 12-month FU, redo procedures, early and late procedure-related complications. Inclusion criteria were the following: indications for AF catheter ablation, planned CBA, a signed informed consent.

32 ablation centers and 1118 patients (572 males, a mean age 68.3±11.4) were included into the registry. Paroxysmal AF was presented in 722 pts, persistent AF – 350 pts, long standing persistent AF – 46 pts. The main underlying diseases were hypertension, coronary artery disease, chronic heart failure; less commonly - hypertrophic cardiomyopathy and dilated cardiomyopathy. The mean LA diameter was 44.7±11.1 mm, LVEF was 62.6±10.8%. The mean BMI was 32.3±3.5 kg/m2. Cardioversion prior to CBA was performed in 32.8%. There were different strategies of AF recurrence documentation: ECG, 24-hour ECG monitor, ECG loop recorder implantation.

Results

The mean temperature of cryoablation was −45.7±17.4 C. The mean fluoroscopy time was 23.98 mins. The mean patient procedure duration was 108.46 mins [min 30; max 266]. The combination of RFA and CBA was reported in 9 cases. Periprocedural anticoagulant therapy included: uninterrupted NOACs (535 pts), bridge anticoagulation (365 pts), uninterrupted warfarin (67 pts), anticoagulation initiated only after CBA (151 pts). Transesophageal echo-guided CBA was performed in 126 cases, intracardiac echocardiography-guided CBA was performed in 474 cases. Esophageal temperature was controlled in 16 cases.

A 12-months follow-up was completed in 906 pts (81.0%). Arrhythmia recurrence was documented in 238 cases (21.3%), mainly AF. Elective cardioversions were performed in 39 pts. Redo ablation procedures were performed in 122 cases. There were a wide range of antithrombotic therapy, as well as pts without anticoagulants despite the fact of AF recurrence. There were 35 (3.1%) CBA-related major adverse events. Esophageal damage was found in 3 cases. There were registered 3 deaths (1 – oncology, and 2 due to unknown cause), 1 MI, 3 persistent phrenic nerve dysfunctions, 3 valve dysfunctions.

Conclusion

This nationwide registry represents contemporary safety and efficacy of CBA for AF. A high success rate of the procedure has been shown during 12 months post procedure. Although a total low number of procedure-related complications has been noted, the occurrence of life-threatening adverse events calls for a caution.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Government of the Russian Federation

Periprocedural anticoagulation in AF cryoballoon ablation in a nationwide registry: no difference in complication rates between strategies

Background

Standard treatment for patients with atrial fibrillation is pulmonary vein isolation (PVI). There are two widely adopted methods for PVI - cryoballon ablation (CBA) and radiofrequency (RF) ablation. There are several randomized studies evaluating different periprocedural anticoagulation strategies in patients undergoing PVI, and those mainly related to RF ablation procedures. However, there is a lack of data on safety of different anticoagulation strategies in CBA.

Purpose

To analyze the current anticoagulation approaches in patients undergoing cryoballoon ablation, the incidence and types of hemorrhagic and thromboembolic periprocedural events. The analysis was performed on data from the National cryoballoon AF ablation registry (NCT03040037).

Methods

Nineteen centers prospectively entered data into a web-based platform. The full data on AC therapy was available in 719 subjects. The specialists evaluated ischemic events clinically, and those included stroke, transient ischemic attack, pulmonary embolism or extracranial systemic embolism. Major bleedings were registered and classified according to the ISTH criteria.

Results

The mean CHA2DS2-VASc score was 2.0±1.4; mean BMI 29.5±4.8; mean GFR 92±28.9 ml/min. Periprocedurally, 574 (79.8%) subjects received direct oral anticoagulants (DOACs), 113 (15.7%) anti-vitamin K drugs (mainly warfarin); 16 (2%) patients received antiplathelet therapy. Uninterrupted DOAC therapy was used in 251 (34.9%) cases. Uninterrupted warfarin therapy was used in 36 (2%) patients. Bridging therapy was used in 325 (45.2%) patients. The total number of major adverse events was 25 (3.5%): 24 of them hemorrhagic and 1 transient ischemic attack (1 female patient on rivaroxaban with bridging). Five (0.7%) patients had hemopericardium: 3 - on uninterrupted rivaroxaban, 1 – rivaroxaban with bridging, 1 – interrupted apixaban. Seventeen (2.5%) patients had groin vascular complications and 1 -hemoptysis. Three patients died within 30 days following CBA from non-cardiovascular causes. There were no statistically significant differences in complications between patients receiving different periprocedural anticoagulation.

Conclusions

About 45% of patients referred for CBA receive bridging anticoagulation therapy in the periprocedural period. Although this is not in line with the current guidelines, we found no meaningful difference in complication rates between different anticoagulation approaches. CBA might be associated with different from RF ablation safety profile and requires randomized trials on periprocedural anticoagulation.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): RF President's council grant

Evaluation of noninvasive electrophysiological imaging accuracy for focal atrial arrhythmias

Background

High accuracy of noninvasive electrocardiographic imaging (ECGI) has recently been shown for topical diagnostics of ventricular arrhythmias. However, the precision of diagnostics of atrial focal arrhythmias requires clarification. To estimate the accuracy of ECGI for premature atrial contraction (PAC) we performed atrial pacing in patients with CRT system and compared early activation zone (EAZ) with pacemaker's tip location.

Purpose

To determine the accuracy of ECGI for focal atrial arrhythmias using atrial pacing.

Methods

Twenty-six patients (m/f – 18/9), age (min–max) 52 (26–78) with CRT system and pacemaker's tip location in the right atrium (RA) appendage underwent ECGI (“Amycard 01C”) in combination with CT or MR imaging. Thirty-four atrial pacing (mono- and bipolar) was performed in all patients using standard amplitude 1.5–3.8 mV. Epi-/endocardial polygonal heart models were created and isopotential maps were calculated. The distance between EAZ and the pacemaker's tip were measured for ECG recordings without using the isoline filter on endocardial surface (Fig. 1) as well as for epicardial surface. The time between epicardial and endocardial EAZ breakthrough was calculated also.

Results

On endocardial surface the EAZ was located in RA appendage, the base of superior cava vena or superior lateral RA wall. The distance (mm) (Me (min; max)) between EAZ and the pacemacer's tip was 28 (6; 68). For epicardial surface in most cases the EAZ was also located in RA appendage, the base of superior cava vena or superior lateral RA wall. In two cases the EAZ was located in inferior septal RA wall, in one case - in superior septal RA wall and in five cases the EAZ was undetectable. The distance between EAZ and the pacemacer's tip was 22 (6; 48). The time (ms) (Mean; Me (min; max)) between EAZ of the endocardial and epicardial surfaces was 16; 7 (0; 68).

Conclusion

ECGI allows to assess the location of focal atrial arrhythmias on endocardial surface and sometimes on epicardial surface also within the three segments. The results of this study revealed that accuracy of ECGI for atrial arrhythmias is worse than for ventricular arrhythmias. However, it is better on epicardial surface of atrium when EAZ can be determined.

Funding Acknowledgement

Type of funding source: None

Exploiting two-dimensional morphology of molybdenum oxycarbide to enable efficient catalytic dry reforming of methane

The two-dimensional morphology of molybdenum oxycarbide (2D-Mo2COx) nanosheets dispersed on silica is found vital for imparting high stability and catalytic activity in the dry reforming of methane. Here we report that owing to the maximized metal utilization, the specific activity of 2D-Mo2COx/SiO2 exceeds that of other Mo2C catalysts by ca. 3 orders of magnitude. 2D-Mo2COx is activated by CO2, yielding a surface oxygen coverage that is optimal for its catalytic performance and a Mo oxidation state of ca. +4. According to ab initio calculations, the DRM proceeds on Mo sites of the oxycarbide nanosheet with an oxygen coverage of 0.67 monolayer. Methane activation is the rate-limiting step, while the activation of CO2 and the C-O coupling to form CO are low energy steps. The deactivation of 2D-Mo2COx/SiO2 under DRM conditions can be avoided by tuning the contact time, thereby preventing unfavourable oxygen surface coverages.

Atomically Dispersed Iridium on Indium Tin Oxide Efficiently Catalyzes Water Oxidation

Heterogeneous catalysts in the form of atomically dispersed metals on a support provide the most efficient utilization of the active component, which is especially important for scarce and expensive late transition metals. These catalysts also enable unique opportunities to understand reaction pathways through detailed spectroscopic and computational studies. Here, we demonstrate that atomically dispersed iridium sites on indium tin oxide prepared via surface organometallic chemistry display exemplary catalytic activity in one of the most challenging electrochemical processes, the oxygen evolution reaction (OER). In situ X-ray absorption studies revealed the formation of IrV=O intermediate under OER conditions with an Ir-O distance of 1.83 Å. Modeling of the reaction mechanism indicates that IrV=O is likely a catalyst resting state, which is subsequently oxidized to IrVI enabling fast water nucleophilic attack and oxygen evolution. We anticipate that the applied strategy can be instrumental in preparing and studying a broad range of atomically dispersed transition metal catalysts on conductive oxides for (photo)electrochemical applications.

P430Antiarrhythmic drug therapy in Russian patients undergoing atrial fibrillation ablation: a sub-analysis of the ESC-EHRA EORP registry

OnBehalf

EHRA-ESC EORP AFA LT registry

Introduction

Despite the effectiveness of atrial fibrillation (AF) catheter ablation (CA), antiarrhythmic therapy (AAT) remains an important part of the complex treatment.

Purpose

To analyze AAT dynamics in Russian patients undergoing AF ablation, and to reveal potential factors associated with ongoing AAT in patients without arrhythmia recurrence.

Methods

The ESC-EHRA AF ablation registry was conducted in 2012-2016 in EHRA countries. The current analysis included 476 patients (57.1 male; 57.1 ± 8.7 years) who underwent AF ablation in 13 Russian clinics. AAT before, during and at 12-month follow-up (12-FU) was assessed. At baseline, paroxysmal AF was present in 320 (67.2%) patients, persistent AF - in 94 (19.7%), long-standing persistent AF- in 53 (11,1%), in 9 (1.9%) AF type was unknown. Hypertension (H) was present in 355 (74.6%) patients; congestive heart failure (CHF) (NYHA≥2) in 184 (38.7%) patients; coronary artery disease (CAD) in 132 (27.7%) patients. The CA was the first in 396 (83.2%) cases, redo ablation was performed in 80 (16.8%) cases. AF recurrences were registered according to local clinical practice. Any atrial tachyarrhythmia &gt;30s was considered as a recurrence.

Results

A three-month FU (3-FU) visit was performed in 476 (100%) patients, 12-FU - in 390 (81.9%). Prior to PV isolation 439 (92.2%) patients received AAT, while after ablation there was an increase in the number of patients on AAT - 459 (96.4%). The highest number of patients on AAT was detected at 3-FU - 463 (97.3%). During 12 months at least one episode of arrhythmia recurrence was documented in 203 (52.1%) patients, and 370 (94.8%) patients were on AAT at the 12-month visit. After the 12-month visit 307 (78.7%) patients continued to receive AAT, and in 187 (47.9%) of them there was no arrhythmia recurrence after the index ablation. Five (2.7%) of these patients continued a Ic class AAT drug, 35 (18.7%) patients - class III, 129 (69.0%) patients - β-blockers (BB) and 18 (9.6%) patients - calcium channel blockers (CCB). All 187 patients had co-morbidities (75.4% - H; 41.7% - CHF (NYHA≥2; 31.6% - CAD). There were no statistically significant predictors of AAT use in patients without arrhythmia reccurence. According to the univariant regression analysis, the use of AAT III class (mainly-sotalol) at 12 months had a small but statistically significant negative association with left atrial size enlargement (OR = 0.917; 0.860-0.997); class III AAT was negatevely associated with BB therapy (OR = 0.057; 0.016-0.198); CCB therapy was associated with an older age (OR = 1.073; 1.053-1.151).

Conclusions

About one-half of patients without apparent arrhythmia recurrence following AF ablation do receive AAT. There were no clinical or procedure-related factors associated with AAT after effective AF ablation. Paradoxically, patients with a smaller left atrial size and without arrhythmia recurrence had more chances to receive class III AAT, what requires further analysis.

P1173Interlead electrical delay time as early predictor of the reverse myocardial remodeling in modern CRT devices

Funding Acknowledgements

Russian Science Foundation Grant №19-14-00134

Background

Cardiac resynchronization therapy (CRT) has undoubtedly shown a high role in the treatment of advanced heart failure (HF). Despite the quadripolar left ventricle (LV) lead widespread use, the problem of low response to CRT remains actual. The search for predictors of the CRT response is an important scientific and practical task.

The aim

To determine the relationship between the interlead electrical delay time and the CRT response during 12 month observational period.

Materials and methods

We evaluated the clinical status, the quality of life and echocardiographic response of 50 patients with HF treated for 1 year with quadripolar LV lead CRT devices implanted according to guidelines: 35 males/15 females with age 62.78 ± 11.58 years, 28 pts with history of ischemic cardiac disease, LVEF 27.42 ± 9.56%; QRS duration 157.34 ± 19.76 ms. The response to CRT was defined as 15% decrease of end-systolic left ventricle (LV) volume (LVESV), 10% relative increase of LV ejection fraction (LVEF), an improvement of at least 1 NYHA HF functional class. Interlead electrical delay time (EDT) was calculated automatically during CRT implantation, and subsequent 3-6-12 month FU. EDT values from 4 LV lead poles were evaluated according to LV sizes, volumes and LVEF.

Results

It was shown that the greater EDT value, the more pronounced was response to CRT. The first difference in EDT is observed after 6-month observational period. The EDT difference was determined using the delta formula for equalize. In 21 patients in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT value, the response to CRT was observed earlier - at 6 months FU (24 pts with maximum EDT value vs. other 26 pts). In addition, the echocardiographic data of reverse myocardial remodeling (LVESD, LVEDD, LVESV, LVEDV and LVEF) correlated with a gradual decrease in the EDT values, r = 0.49, P = 0.008. There were no differences between the HF etiology (ischemic/ non-ischemic) and baseline rhythm. The mean EDT was initially 104.94 ± 44.22 ms, 6 month FU 98.91 ± 34.28 ms, 12 month FU 91.84 ± 32.78 ms.

Conclusion

The interlead electrical delay time in quadripolar CRT devices depends on reverse myocardial remodeling. EDT gradual decrease may be a predictor of the response to CRT.

Abstract Figure. Interlead Delay Time 12M Follow Up

P1422Low incidence of major procedure-related adverse events of cryoballoon ablation in real practice: an interim analysis of the Russian national prospective cryoablation registry

OnBehalf

On Behalf Of the National Cryoballoon Registry Investigators

Background

Cryoballoon ablation (CBA) is an effective strategy for atrial fibrillation (AF) management. The Russian Cryoballoon Atrial Fibrillation Ablation Registry (NCT03040037) is a prospective observational multicenter national registry that aims to provide real-world efficacy, safety and outcomes of this technology.

Methods

A specialized Web-based registry platform was developed for prospective data entry. The platform consists of 8 sections: AF ablation clinic experience and operator experience, patient characteristics, CBA procedure characteristics, periprocedural patient management (including drug therapy),  12-moths follow-up with scheduled and unscheduled visits, redo procedure characteristics, early and late procedure-related complications. Patient inclusion criteria were the following: indications for AF catheter ablation, planned CBA, a signed informed consent.

Results

To date thirty-one clinics have joined the Registry, and 830 patients (477 males, a mean age 65.4 ± 11.3 years) were included. The mean BMI was 33.2 ± 3.3 kg/m2. Paroxysmal AF was presented in 688 pts, persistent AF – 111 pts, long standing persistent AF – 31 pts. The main underlying diseases were hypertension (75%), coronary artery disease (11%), chronic heart failure (25%); less commonly - hypertrophic cardiomyopathy (1.4%) and dilated cardiomyopathy (0.7%). The mean LA diameter was 45.4 ± 10.2 mm, and LVEF was 65.4 ± 12.6%.

Periprocedural anticoagulant therapy included

uninterrupted NOACs (313 pts), bridge anticoagulation (327 pts), uninterrupted warfarin (45 pts), anticoagulation initated only after CBA (32 pts). The mean temperature of cryoablation was -44.6 ± 16.3 C. Transesophageal echo-guided  CBA was performed in 92 cases , intracardiac echocardiography-guided - in 465 cases. There were 5 (0.6%) cases of hemopericardium, and pericardiocentesis was required in 1 (0.1%) case only. Periprocedural TIA was diagnosed in 1 (0.1%) patient with bridge anticoagulation, no stroke occurred. Transient phrenic nerve injury was detected in 18 (2.1%) patients, persistent palsy – in 1 (0.1%) patient. Two cases of esophageal injury were reported, no surgery was required and healing was reported in both patients. The data collection is ongoing.

Conclusion

We report early results of the ongoing national CBA Registry. There was a low number of major procedure-related adverse events in real clinical practice among centers with different AF ablation experience. Long-term follow up of the included patients will be reported in the future.

Abstract Figure. Antithrombotic therapy and CBA

Preventive or Deferred Ablation of Ventricular Tachycardia in Patients With Ischemic Cardiomyopathy and Implantable Defibrillator (BERLIN VT)

Background:

Catheter ablation for ventricular tachycardia (VT) reduces the recurrence of VT in patients with implantable cardioverter-defibrillators (ICDs). The appropriate timing of VT ablation and its effects on mortality and heart failure progression remain a matter of debate. In patients with life-threatening arrhythmias necessitating ICD implantation, we compared outcomes of preventive VT ablation (undertaken before ICD implantation to prevent ICD shocks for VT) and deferred ablation after 3 ICD shocks for VT.

Methods:

The BERLIN VT study (Preventive Ablation of Ventricular Tachycardia in Patients With Myocardial Infarction) was a prospective, open, parallel, randomized trial performed at 26 centers. Patients with stable ischemic cardiomyopathy, a left ventricular ejection fraction between 30% and 50%, and documented VT were randomly assigned 1:1 to a preventive or deferred ablation strategy. The primary outcome was a composite of all-cause death and unplanned hospitalization for either symptomatic ventricular arrhythmia or worsening heart failure. Secondary outcomes included sustained ventricular tachyarrhythmia and appropriate ICD therapy. We hypothesized that preventive ablation strategy would be superior to deferred ablation strategy in the intention-to-treat population.

Results:

During a mean follow-up of 396±284 days, the primary end point occurred in 25 (32.9%) of 76 patients in the preventive ablation group and 23 (27.7%) of 83 patients in the deferred ablation group (hazard ratio, 1.09 [95% CI, 0.62–1.92]; P =0.77). On the basis of prespecified criteria for interim analyses, the study was terminated early for futility. In the preventive versus deferred ablation group, 6 versus 2 patients died (7.9% versus 2.4%; P =0.18), 8 versus 2 patients were admitted for worsening heart failure (10.4% versus 2.3%; P =0.062), and 15 versus 21 patients were hospitalized for symptomatic ventricular arrhythmia (19.5% versus 25.3%; P =0.27). Among secondary outcomes, the proportions of patients with sustained ventricular tachyarrhythmia (39.7% versus 48.2%; P =0.050) and appropriate ICD therapy (34.2% versus 47.0%; P =0.020) were numerically reduced in the preventive ablation group.

Conclusions:

Preventive VT ablation before ICD implantation did not reduce mortality or hospitalization for arrhythmia or worsening heart failure during 1 year of follow-up compared with the deferred ablation strategy.

Registration:

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02501005.

Enhanced CH3OH selectivity in CO2 hydrogenation using Cu-based catalysts generated via SOMC from GaIII single-sites

Small and narrowly distributed nanoparticles of copper alloyed with gallium supported on silica containing residual Ga^III sites can be obtained via surface organometallic chemistry in a two-step process: (i) formation of isolated Ga^III surface sites on SiO₂ and (ii) subsequent grafting of a Cu^I precursor, [Cu(O ^t Bu)]₄, followed by a treatment under H₂ to generate CuGa _x alloys. This material is highly active and selective for CO₂ hydrogenation to CH₃OH. In situ X-ray absorption spectroscopy shows that gallium is oxidized under reaction conditions while copper remains as Cu⁰. This CuGa material only stabilizes methoxy surface species while no formate is detected according to ex situ infrared and solid-state nuclear magnetic resonance spectroscopy.

Spatially resolved NMR spectroscopy of heterogeneous gas phase hydrogenation of 1,3-butadiene with parahydrogen

Glass tube reactors with Pd, Pt, Rh or Ir nanoparticles dispersed on a thin layer of TiO₂, CeO₂, SiO₂ or Al₂O₃ provided mechanistic insight into the hydrogenation of 1,3-butadiene using parahydrogen.

P5692Catheter ablation of ventricular tachyarrhythmias in ischemic patients may contribute to better survival: a new clinical challenge

Background

Ventricular arrhythmias contribute to significant escalation of mortality rate in patients with ischemic cardiomyopathy (ICM). Risk of sudden cardiac death (SCD) could be reduced after implantation of a cardioverter-defibrillator (ICD), yet at the same time more frequent shock episodes are associated with poor life quality and higher hospitalization rate. Radiofrequency (RF) ablation of triggering ventricular premature beats or substrate-based catheter treatment are considered to be effective in patients with ICM but prognosis remains controversial.

Objective

To evaluate role of catheter treatment of ventricular tachyarrhythmias (VTA) and its effect on survival in patients with ischemic cardiomyopathy.

Methods

We enrolled 72 consecutive patients (mean age 64±13 years, 63 male) with prior myocardial infarction (more than 40 days ago) and documented ventricular tachycardia (VT) episodes, including 12 patients which underwent emergency electrical storm ablation. Considering number of VT recurrence episodes after catheter treatment all patients were divided into two groups. First group consisted of 27 patients (37%) with recurrent sustained VT (mean age 62±10 years) while second group included 45 patients (63%) without VT recurrence (mean age 63±12 years). During follow up most of VT episodes were registered in 13±9 years after acute myocardial infarction. Catheter treatment included mapping during hemodynamically tolerated clinically relevant VT and then ablation of VT triggers with subsequent homogenization of the scar. Patients with “fast” VT underwent primary scar homogenization.

Results

Effectiveness of clinically relevant VT ablation in patients with ICM was 63%. During follow-up period all patients were alive and remained relatively stable. Long-term effectiveness of ES elimination was 100% while freedom from clinically significant VTA was up to 79% due to repeated ablation procedures. We also observed improvement of NYHA functional class in 80% of patients.

Conclusion

Catheter ablation of VTA may be effective treatment both in acute period and long term follow up. It also may be effective in improvement of heart failure NYHA functional class in some patients and contributes to better survival in patients with ICM.

P5696The first results from multicentre study of noninvasive epi-endocardial panoramic mapping of ventricular arrhythmias

Background

A noninvasive epi-endocardial panoramic mapping is a promising ECG Imaging technology alternative to catheter-based invasive methods. Some unstable ventricular arrhythmias arising from complex anatomic sites render mapping and ablation difficulties with conventional approach.

Objective

To assess the use of a noninvasive panoramic mapping for diagnosis and localization of ventricular arrhythmias.

Methods

35 patients (20 male, median (25–75%) age – 35 (12–60) years) with polymorphic premature ventricular contractions (PVCs) and 3–5 different QRS morphologies (1500–19000 per day) or monomorphic ventricular tachycardia (VT) were enrolled in the study. Up to 224 body surface electrodes were connected to the noninvasive epi-endocardial electrophysiological system for multichannel ECG recording followed by computed tomography of the heart and torso. The body-surface ECG data were processed using inverse-problem solution software in combination with realistic 3D anatomical models of the heart and torso. The earliest site of activation were determined on isopotential maps for each QRS morphology. On the same day patients underwent catheter ablation of one or two dominant PVC morphologies using 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. Afterwards, electroanatomical maps were exported from Carto 3 system and compared with noninvasive maps using custom written Python-based software.

Results

In total 47 similar PVC morphologies in 30 patients were mapped using noninvasive and invasive electroanatomical mapping systems, 34 (72%) PVCs were correctly diagnosed and 13 (28%) did not accurately correspond with sites of radiofrequency ablation. In 2 patients with four PVC morphologies an early activation zones were determined as a breakthrough from epi and endocardial surface using noninvasive activation maps.

Conclusion

Non invasive epi-endocardial panoramic mapping technology is a novel diagnostic method which can be used as an additional pre-procedural tool for topical diagnosis of polymorphic PVCs.

ECG Adapted Fastest Route Algorithm to Localize the Ectopic Excitation Origin in CRT Patients

Although model-based solution strategies for the ECGI were reported to deliver promising clinical results, they strongly rely on some a priori assumptions, which do not hold true for many pathological cases. The fastest route algorithm (FRA) is a well-established method for noninvasive imaging of ectopic activities. It generates test activation sequences on the heart and compares the corresponding test body surface potential maps (BSPMs) to the measured ones. The test excitation propagation patterns are constructed under the assumption of a global conduction velocity in the heart, which is violated in the cardiac resynchronization (CRT) patients suffering from conduction disturbances. In the present work, we propose to apply dynamic time warping (DTW) to the test and measured ECGs before measuring their similarity. The warping step is a non-linear pattern matching that compensates for local delays in the temporal sequences, thus accounting for the inhomogeneous excitation propagation, while aligning them in an optimal way with respect to a distance function. To evaluate benefits of the temporal warping for FRA-based BSPMs, we considered three scenarios. In the first setting, a simplified simulation example was constructed to illustrate the temporal warping and display the resulting distance map. Then, we applied the proposed method to eight BSPMs produced by realistic ectopic activation sequences and compared its performance to FRA. Finally, we assessed localization accuracy of both techniques in ten CRT patients. For each patient, we noninvasively imaged two paced ECGs: from left and right ventricular implanted leads. In all scenarios, FRA-DTW outperformed FRA in terms of LEs. For the clinical cases, the median (25-75% range) distance errors were reduced from 16 (8-23)mm to 5 (2-10)mm for all pacings, from 15 (11-25)mm to 8 (3-13)mm in the left, and from 19 (6-23)mm to 4 (2-8)mm in the right ventricle, respectively. The obtained results suggest the ability of temporal ECG warping to compensate for an inhomogeneous conduction profile, while retaining computational efficiency intrinsic to FRA.