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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.

Background Ischemic heart disease (IHD) is a major underlying etiology in patients with heart failure (HF). Although the impact of IHD on HF is evolving, there is a lack of understanding of how IHD affects long-term clinical outcomes and uncertainty about the role of IHD in determining the risk of clinical outcomes by gender. Purpose This study aims to evaluate the gender difference in impact of IHD on long-term clinical outcomes in patients with heart failure reduced ejection fraction (HFrEF). Methods Study data were obtained from the nationwide registry which is a prospective multicenter cohort and included patients who were hospitalized for HF composed of 3,200 patients. A total of 1,638 patients with HFrEF were classified into gender (women 704 and men 934). The primary outcome was all-cause death during follow-up and the composite clinical events of all-cause death and HF readmission during follow-up were also obtained. HF readmission was defined as re-hospitalization because of HF exacerbation. Results 133 women (18.9%) were died and 168 men (18.0%) were died during follow-up (median 489 days; inter-quartile range, 162–947 days). As underlying cause of HF, IHD did not show significant difference between genders. Women with HFrEF combined with IHD had significantly lower cumulative survival rate than women without IHD at long-term follow-up (74.8% vs. 84.9%, Log Rank p=0.001, Figure 1). However, men with HFrEF combined with IHD had no significant difference in survival rate compared with men without IHD (79.3% vs. 83.8%, Log Rank p=0.067). After adjustment for confounding factors, Cox regression analysis showed that IHD had a 1.43-fold increased risk for all-cause mortality independently only in women. (odds ratio 1.43, 95% confidence interval 1.058–1.929, p=0.020). On the contrary to the death-free survival rates, there were significant differences in composite clinical events-free survival rates between patients with HFrEF combined with IHD and HFrEF without IHD in both genders. Figure 1 Conclusions IHD as predisposing cause of HF was an important risk factor for long-term mortality in women with HFrEF. Clinician need to aware of gender-based characteristics in patients with HF and should manage and monitor them appropriately and gender-specifically. Women with HF caused by IHD also should be treated more meticulously to avoid a poor prognosis. Acknowledgement/Funding None

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 <5: normal, 5≤RDI<15: Mild, 15≤RDI<30: moderate, 30≤RDI: severe). The presence of stroke risk factors (left atrial appendage [LAA] pulse wave velocity < 20cm/sec, NT pro BNP >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.