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Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Korea University Introduction Implantable loop recorder (ILR) is useful to reveal hidden arrhythmia. The real-world using trend of ILR implantation and indication were studied using nationwide database. Purpose To assess the indication of ILR and diagnostic rate of meaningful arrhythmia Method We analyzed the 1,460 patients who underwent ILR implantation (male 62%, mean age 62±16) from 2008 to 2019 using Korea Health Insurance review and assessment service database. Result The embolic stroke of undetermined source (ESUS) group, syncope group and palpitation group were 619 (42.3%), 765 (52.3%), 76 (5.2%) as implantation indication, respectively. From 2016 to 2019, the ESUS group increased by 14 times and the syncope group by 4 times. Among patients with ESUS, 191 patients (31%) were diagnosed with atrial fibrillation within 1 year. Bradycardia needed pacing therapy was revealed in 28%, tachycardia in 6% and atrial fibrillation in 24% in syncope group. The predictors of atrial fibrillation in ESUS group were age (OR: 1.024 per year, CI: 1.006-1.042, p=0.0072) and heart failure (OR: 2.215, CI:1.357-3.615, p=0.0015). The mean time from ILR to pacing therapy was 3±2 months in syncope group and that to anticoagulation in ESUS group was 6±3 months. Discussion The use of ILR for evaluation of ESUS is increasing, with atrial fibrillation diagnostic rate of 30%. The time to treatment differed by group.

Funding Acknowledgements Type of funding sources: None. Background/Introduction Proton pump inhibitor is commonly used for gastroprotective effect in patients with a combination of antiplatelets and anticoagulants. However, data quantifying the concomitant proton pump inhibitor for clinical adverse outcomes other than gastrointestinal bleedings of oral anticoagulant is lacking. Purpose We aimed to explore the effect of concomitant proton pump inhibitor on the effectiveness and safety of oral anticoagulant in patients with atrial fibrillation. Methods The medical records were retrospectively reviewed from four tertiary referral hospitals between January 1, 2012, and December 31, 2020. Concomitant use of drug was quantified as the overlapping proportion over the duration of oral anticoagulant therapy. Primary endpoint was the time to occurrence of ischemic stroke, systemic embolism, intracardiac thrombus, major bleeding events, or death. Results Data were analyzed for 20,750 episodes with oral anticoagulant and atrial fibrillation (median [IQR] age, 71 [63-78] years; female, 42.5%; warfarin, 37.3%; median [IQR] CHA2DS2-VASc score, 3 [2-5]). The risk of primary endpoint was greatest in the group of persistent use (80% or more of overlapping proportion) of proton pump inhibitor among the other groups with less overlapping proportion (adjusted hazard ratio, 1.88; 95% confidence interval, 1.63–2.16; P for groups, Conclusion Among patients with atrial fibrillation receiving oral anticoagulant, concomitant use of proton pump inhibitor increased the rate of thromboembolism, major bleeding, or death in proportion of overlapping period.

Funding Acknowledgements Type of funding sources: None. Backgrounds Novel oral anticoagulants (NOACs) are effective to prevent stroke in patients with atrial fibrillation. Real world long-term data on the efficacy and safety of NOACs compared to warfarin in Asians are lacking. Purpose We aimed to explore the effectiveness and safety of NOAC in Asian patients with atrial fibrillation. Methods The medical records were reviewed in registry of four tertiary referral hospitals between January 1, 2012, and December 31, 2020. The primary outcome was the composite of thromboembolism, major bleeding and all caused mortality. Results Data were analyzed for 19,994 participants with oral anticoagulant and atrial fibrillation (median age, 72 years; female, 41.5%; warfarin, 35.5%; median CHA2DS2-VASc score, 3). The rate of the primary outcome was 5.5% per year in the NOAC group, as compared with 6.0% per year in the warfarin group (HR with NOAC, 0.70; 95% confidence interval [CI], 0.63 to 0.77; P conclusion In Asian patients with atrial fibrillation, NOAC was effective and safe to prevent thromboembolic events with less bleeding compared to warfarin.

Funding Acknowledgements Type of funding sources: None. Introduction Obstructive sleep apnea (OSA) is associated with left atrial (LA) remodeling, which increases the thromboembolic risk of atrial fibrillation (AF) and recurrence of atrial fibrillation after catheter ablation of AF. This study aimed to assess the association between severity of OSA and LA remodeling. Method In 126 patients with AF who underwent catheter ablation for AF (male 78.4% male, 58.0 ± 10 years old, persistent AF 27%), LA voltage distribution were analyzed during atrial pacing. All the subjects underwent polysomnography for screening of OSA. We categorized the subjects into 4 groups based on the severity of OSA which was determined by the respiratory disturbance index (RDI; RDI 1,250 ng/l, presence of spontaneous echo contrast [SEC] and LA volume index >32 ml/m3) were evaluated. Result The LA low voltage area was significantly greater (p=0.007) and LA volume measured by cardiac magnetic resonance imaging (MRI) was significantly larger with the severity of OSA (p=0.004). The presence of SEC (3.2% vs. 13.6%; p=0.201) and LAA pulse wave velocity < 20cm/sec (3.2% vs. 9.6%; p=0.454) were higher in patients with moderate to severe OSA but it did not reach statistical significance. In the multivariate regression analysis, the total number of the stoke risk factors other than CHA2DS2-VASc was significantly associated with RDI (β=0.191; p=0.037). Conclusion The severity of OSA has significant relationship with stroke risk factors.

Background/Introduction Signal-averaged electrocardiography (SA-ECG) is a high-resolution electrocardiography that can detect late ventricular potential, which known to be a noninvasive tool for risk stratification of sudden cardiac death (SCD) by predicting reentrant ventricular tachyarrhythmia. There is a paucity of data with SA-ECG on SCD survivors without structural heart disease, whereas majority of previous studies had been focused on post myocardial infarction survivors. Purpose This study assessed the clinical utility of SA-ECG as a risk stratification modality for lethal arrhythmic event in patients at risk of SCD without definite structural heart disease. Methods Total 629 patients who experienced or had potential risk of SCD were studied with SA-ECG. Among them, 48 patients who were found to have significant structural heart disease were excluded, except arrhythmogenic right ventricular cardiomyopathy. Major arrhythmic event (MAE) was defined as composite of all-cause death, aborted SCD, and sustained VT during any time either before visit of clinic or during follow up period. Syncope and non-sustained VT was defined as non-major arrhythmic event. SA-ECG was defined positive when fulfilling three or more criterion: (1) unfiltered QRS duration ≥114ms, (2) filtered QRS duration ≥114ms, (3) duration of terminal QRS Results Among total 581 patients, 145 patients with positive SA-ECG showed higher incidence of MAE compared to patients with negative SA-ECG (21.4% vs. 6.7%, OR 3.816 [95% CI 2.208–6.597], p Conclusion This study showed that at least 3 out of 4 diagnostic criteria in SA-ECG can independently predict lethal arrhythmic events and the positive late potential was associated with lethal arrhythmic event that leads to SCD, suggesting risk prediction for SCD using SA-ECG in patients even without structural heart disease including inherited arrhythmias. Funding Acknowledgement Type of funding sources: None.

Background/Introduction Brugada syndrome (BrS) and arrhythmogenic right ventricular cardiomyopathy (ARVC) are inherited arrhythmias that may predispose to sudden cardiac arrest. Although its pathogenetic mechanisms differ, overlapping features between BrS and ARVC have been demonstrated previously. However, it remains to be determined whether genetic testing for ARVC-related gene is needed in patients with BrS. Purpose This study is aimed to analyze genetic profiles of BrS patients using next generation sequencing (NGS) based multigene panel including ARVC related genes. Methods Patients who were confirmed as BrS or clinically suspected as BrS with type 2 or 3 Brugada pattern electrocardiography were studied. Genetic testing using NGS panels (Illumina Inc., San Diego, CA, USA) included 30 genetic variants associated with inherited arrhythmia and genetic cardiomyopathy. Results Among the total 119 patients from BrS registry, 63 patients were confirmed as BrS and 56 patients were clinically suspected as BrS without fulfilling diagnostic criteria. One-hundred-fourteen patients (95.8%) were male, and mean age of onset was 43.6 year-old. Genetic variants were identified in 25 of 42 patients who received genetic testing. Six out of 25 patients (24.0%) showed ARVC-related genotypes (2 PKP2, 1 DSG2, 1 TMEM43, 1 JUP, and 1 DSP) (Figure 1 and Table 1). None of the patients showed structural or electrocardiographic features that fulfill diagnostic criteria of ARVC. It is notable that ARVC-related genotypes were mostly frequently accounted for BrS patients, following SCN5A and SCN10A. Conclusion In the clinic setting, ARVC-related genetic variants were identified in significant proportion of BrS patients, supporting that genetic testing of ARVC-overlapping is needed. This study suggests that follow-up including imaging study should be considered in BrS patients with ARVC-related genotypes to monitor disease progression as ARVC. Funding Acknowledgement Type of funding sources: None.

A high concentration of ultra-high-energy cosmic ray (UHECR) events, called a hotspot, was reported by the Telescope Array (TA) experiment, but its origin still remains unsolved. One of the obstacles is that there is no astronomical object, which could be the source, behind the TA hotpot. In an effort to understand the origin of the TA hotspot, we suggested a model based on the magnetized cosmic web structure. The UHECRs were produced from sources in the Virgo cluster and were initially confined by cluster magnetic fields for a certain period. Next, some of them preferentially escaped to and propagated along filaments. Eventually, they were scattered by filament magnetic fields, and come to us. To examine the model, we followed the propagation trajectories of UHE protons in a simulated universe with clusters, filaments, and voids, by employing a number of models for cosmic magnetic fields. In this study, we present some of the initial results, such as the ratio between the particles directly escaping from the clusters to the voids and particles escaping from the clusters to the filaments. We also discuss the feasibility of our model for the origin of the hotspot by examining the trajectories of the UHE protons., 8 pages, 2 figures, Proceedings of the 36th International Cosmic Ray Conference (ICRC 2019), July 24th - August 1st, Madison, WI, USA

We measure the spectrum of cosmic rays with energies greater than 10 18.2 eV with the fluorescence detectors (FDs) and the surface detectors (SDs) of the Telescope Array Experiment using the data taken in our first 2.3-year observation from May 27, 2008 to September 7, 2010. A hybrid air shower reconstruction technique is employed to improve accuracies in determination of arrival directions and primary energies of cosmic rays using both FD and SD data. The energy spectrum presented here is in agreement with our previously published spectra and the HiRes results.

The stability of the gain of the photomultiplier (PMT) camera for the Fluorescence Detector (FD) of the Telescope Array experiment was monitored using an 241 Am loaded scintillator pulsers (YAP) and a diffused xenon flasher (TXF) for a selected set of 35 PMT-readout channels. From the monitoring of YAP pulses over four years of FD operation, we found slow monotonic drifts of PMT gains at a rate of −1.7~+1.7%/year. An average of the PMT gains over the 35 channels stayed nearly constant with a rate of change measured at −0.01±0.31(stat)±0.21(sys)%/year. No systematic decrease of the PMT gain caused by the night sky background was observed. Monitoring by the TXF also tracked the PMT gain drift of the YAP at 0.88±0.14(stat)%/year.

We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array’s third fluorescence detector [T. Abu-Zayyad et al., The energy spectrum of Telescope Array’s middle drum detector and the direct comparison to the high resolution fly’s eye experiment, Astroparticle Physics 39 (2012) 109-119, http://dx.doi.org/10.1016/j.astropartphys.2012.05.012 , Available from: ]. This combined spectrum corroborates the recently published Telescope Array surface detector spectrum [T. Abu-Zayyad, et al., The cosmic-ray energy spectrum observed with the surface detector of the Telescope Array experiment, ApJ 768 (2013) L1, http://dx.doi.org/10.1088/2041-8205/768/1/L1 , Available from: ] with independent systematic uncertainties.

We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E>57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure of the Universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the Universe (the LSS hypothesis), while the event set with E>10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis., 10 pages, 9 figures

We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above ${10}^{19}$, ${10}^{19.5}$, and ${10}^{20}\text{ }\text{ }\mathrm{eV}$ based on the first three years of data taken.

We search for correlations between positions of extragalactic objects and arrival directions of Ultra-High Energy Cosmic Rays (UHECRs) with primary energy $E \ge 40$ EeV as observed by the surface detector array of the Telescope Array (TA) experiment during the first 40 months of operation. We examined several public astronomical object catalogs, including the Veron-Cetty and Veron catalog of active galactic nuclei. We counted the number of TA events correlated with objects in each catalog as a function of three parameters: the maximum angular separation between a TA event and an object, the minimum energy of the events, and the maximum redshift of the objects. We determine combinations of these parameters which maximize the correlations, and calculate the chance probabilities of having the same levels of correlations from an isotropic distribution of UHECR arrival directions. No statistically significant correlations are found when penalties for scanning over the above parameters and for searching in several catalogs are taken into account.

Cosmic rays with energy exceeding ~ 10^{18} eV are referred to as ultra-high energy cosmic rays (UHECRs). Monte Carlo codes for extensive air shower (EAS) simulate the development of EASs initiated by UHECRs in the Earth's atmosphere. Experiments to detect UHECRs utilize EAS simulations to estimate their energy, arrival direction, and composition. In this paper, we compare EAS simulations with two different codes, CORSIKA and COSMOS, presenting quantities including the longitudinal distribution of particles, depth of shower maximum, kinetic energy distribution of particle at the ground, and energy deposited to the air. We then discuss implications of our results to UHECR experiments., Comment: To appear in Astroparticle Physics. Pdf can also be downloaded from http://canopus.cnu.ac.kr/ryu/eas1.pdf

The Telescope Array's Middle Drum fluorescence detector was instrumented with telescopes refurbished from the High Resolution Fly's Eye's HiRes-1 site. The data observed by Middle Drum in monocular mode was analyzed via the HiRes-1 profile-constrained geometry reconstruction technique and utilized the same calibration techniques enabling a direct comparison of the energy spectra and energy scales between the two experiments. The spectrum measured using the Middle Drum telescopes is based on a three-year exposure collected between December 16, 2007 and December 16, 2010. The calculated difference between the spectrum of the Middle Drum observations and the published spectrum obtained by the data collected by the HiRes-1 site allows the HiRes-1 energy scale to be transferred to Middle Drum. The HiRes energy scale is applied to the entire Telescope Array by making a comparison between Middle Drum monocular events and hybrid events that triggered both Middle Drum and the Telescope Array's scintillator Ground Array., Comment: 27 pages, 21 figures

The Telescope Array (TA) experiment, located in the western desert of Utah, USA, is designed for the observation of extensive air showers from extremely high energy cosmic rays. The experiment has a surface detector array surrounded by three fluorescence detectors to enable simultaneous detection of shower particles at ground level and fluorescence photons along the shower track. The TA surface detectors and fluorescence detectors started full hybrid observation in March, 2008. In this article we describe the design and technical features of the TA surface detector. © 2012 Elsevier B.V., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

The Telescope Array is a detector of extensive air shower produced by ultra High energy cosmic ray. This detector is located on Utah, USA. The construction have been completed and the full operation has been running from March 2008. In this talk, the status of observation and our prospects are described.

The Telescope Array (TA) collaboration has measured the energy spectrum of ultra-high energy cosmic rays with primary energies above 1.6 x 10^(18) eV. This measurement is based upon four years of observation by the surface detector component of TA. The spectrum shows a dip at an energy of 4.6 x 10^(18) eV and a steepening at 5.4 x 10^(19) eV which is consistent with the expectation from the GZK cutoff. We present the results of a technique, new to the analysis of ultra-high energy cosmic ray surface detector data, that involves generating a complete simulation of ultra-high energy cosmic rays striking the TA surface detector. The procedure starts with shower simulations using the CORSIKA Monte Carlo program where we have solved the problems caused by use of the "thinning" approximation. This simulation method allows us to make an accurate calculation of the acceptance of the detector for the energies concerned., Comment: Accepted for publication by Astrophysical Journal Letters

The purpose of The Telescope Array experiment is to identify origin of the ultra high energy cosmic rays. The Telescope Array is a hybrid detector consists of a surface detector array and air fluorescence detectors. This hybrid detector is observing extensive air showers to measure the energy spectrum, anisotropy and composition of Ultra High Energy Cosmic Rays. The detector construction has been completed in March 2008, and the hybrid observation with the full configuration has been running since that time. In this talk, the status of observation and our prospects are described.