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Background Left atrial appendage thrombi (LAAT), especially movable type LAAT, have been reported to be high-risk for thromboembolic events in patients with atrial fibrillation (AF). However, thromboembolic risk of the movable-type LAAT under widespread use of anticoagulant therapy remains unclear. Methods We retrospectively studied 65 LAAT patients taking anticoagulants out of 1381 consecutive patients who underwent transthoracic echocardiography prior to cardioversion or catheter ablation for AF. Patients with significant valvular disease and coagulation disorder were excluded. Clinical data were evaluated at the time of TEE. The LAAT were classified into movable and fixed type LAAT by three independent observers. Results Sixteen of 65 LAAT patients showed movable type LAAT. During follow-up (42±34 months), one patient underwent emergency thrombectomy, 5 patients developed thromboembolic event, and 12 patients died. There were no differences in clinical data, parameters, thrombectomy/thromboembolic event, and survival rate between patients with movable and fixed type LAAT. Conclusion Thromboembolic risk of the movable-type LAAT is the same as fixed type LAAT, under widespread use of anticoagulant therapy. Funding Acknowledgement Type of funding sources: None.

Background The abnormal conduction zone (ACZ) in the left atrium (LA) has attracted attention as an arrhythmia substrate in atrial fibrillation (AF). Purpose We investigated whether the ACZ affects outcomes after catheter ablation (CA) for AF. Methods We studied 78 patients (42 Non-paroxysmal AF, 49 males, and 68±10 years) who received CA for AF. High-density LA mapping during high right atrial pacing was constructed gaining than 2000 points (average 4377±846 points). Isochronal activation maps created at 5-ms interval setting. ACZ was identified by locating a site with isochronal crowding of ≥3 isochrones, and ≥8 isochrones were defined as the conduction block zone (CBZ) in a 4-mm diameter tag (conduction velocity were calculated as ≤27 cm/s and≤10 cm/s, respectively). Result Recurrent AF was detected in 25/78 patients (32%) during the follow-up period (9.2±3.0 month). ACZ and CBZ were distributed linearly, and ACZ was observed in 73 of 78 patients and 8 of these 73 patients had the CBZ. Univariate analysis revealed that elevated body mass index (26.2±3.8 vs. 24.3±3.3 kg/m2, P=0.0303), the higher prevalence of non-paroxysmal AF (72% vs. 45%, P=0.0272), larger LA diameter (47.6±6.6 vs. 42.1±6.9 mm, P=0.0014), and longer length of ACZ (79.7±45.1 vs. 52.9±35.7 mm, P=0.0058) were associated with recurrent AF after CA. On multivariate analysis, longer ACZ was independently associated with recurrent AF. Moreover, patients with longer ACZ (cutoff value: 84 mm) had a higher risk of recurrent AF than shorter ACZ (12/22; 55% vs 13/56; 23%, log-rank P=0.0024). Conclusion The length of ACZ was associated with recurrent AF after CA. Funding Acknowledgement Type of funding sources: None.

Background It has been reported that low voltage areas and conduction abnormalities detected by electrophysiology catheters in the left atrium (LA) represent regional degeneration and fibrosis of the atrium and are related to a poor atrial fibrillation (AF) ablation outcome. Assessment of the local atrial function is clinically useful because atrial degeneration does not occur uniformly throughout the atrium. Though evaluating the global atrial function using speckle tracking imaging (STI) by transthoracic echocardiography (TTE) has been attempted, TTE does not have a sufficient image quality to assess local atrial STI. Purpose To evaluate the local atrial function by STI using intracardiac echocardiography (ICE) and to elucidate the characteristics of the STI in normal and abnormal voltage regions in the LA. Methods We included 9 patients undergoing AF ablation with written informed consent for this prospective observational study. After pulmonary vein isolation, we performed voltage mapping of the LA in sinus rhythm using a CARTO system (Biosense). Abnormal regions and normal regions were defined as those with low voltage areas ( Results Among the study population, 5 patients had low voltage areas in the LA. We evaluated the STI at 26 normal regions and 44 abnormal regions. The typical regional speckle tracking waveform in the normal region was similar to a jugular vein pressure waveform (right figure). There was a difference in the amplitude of the Sct between the groups; it was significantly smaller in the abnormal regions (normal and abnormal regions, 9.8±5.0% and 5.6±3.8%, p=0.0001). The duration of the Sct was significantly more prolonged in the abnormal regions than normal regions (98.8±26.3ms and 118.2±33.9ms, p=0.015). Conclusions This pilot study demonstrated that the local atrial function was evaluable by STI using ICE and that the regional strain tracking waveform during the atrial contraction phase in abnormal voltage regions was smaller and more prolonged than that in normal regions. An evaluation of the regional STI with an ICE may be useful to detect regional abnormalities of the atrium. Representative case Funding Acknowledgement Type of funding source: None

Background Preoperative left atrial (LA) function is associated with paroxysmal atrial fibrillation (PAF) ablation outcome. The presence of left atrial low voltage zone (LVZ) is also associated with recurrence. We hypothesized that reduced pre-ablation LA function reflects the presence of LVZ. Purpose We investigated the association between baseline LA function and the presence of LVZ in patients undergoing initial PAF ablation. Further, we sought to create the new predictive scoring for the presence of LVZ. Methods Consecutive 305 patients who underwent LA voltage mapping during initial PAF ablation from January 2017 to October 2019 in our institute were retrospectively analyzed. We performed 256-slice MDCT at baseline. As the representative of LA function, we calculated LA emptying fraction (LAEF), where LAEF = {[(maximum LAV) − (minimum LAV)]/(maximum LAV)} x 100. LVZ was defined as regions where bipolar peak-to-peak voltage was Results Out of 305 pts, 56 pts (18%) had LVZ in LA. In univariate analysis, low body mass index, higher percentage of female sex, higher age, higher E/e', larger maximum LA volume and lower LAEF (29.3±11.8% vs. 41.2±9.7, P Conclusions In PAF patients, preoperative LAEF was strongly associated with the presence of LVZ. LVZ might reflect the myocardial injury causing LA dysfunction. OLAF-LVZ predictive score: combination of Old age (≥65), Female sex, and LAEF (≤31%) could be useful to stratify the risk of the presence of LVZ. Funding Acknowledgement Type of funding source: None

Background While multiple catheter ablation for recurrent atrial fibrillation (AF) is effective for the maintenance of sinus rhythm, some of patients have ablation-refractory AF. Left atrial (LA) dysfunction and the presence of low voltage zone (LVZ) are associated with recurrence after AF ablation. The association between recurrence and LA dysfunction/ LVZ among patients undergoing multiple AF ablation remains unclear. Purpose We aimed to compare (i)LA function, (ii)the prevalence of LVZ among patients undergoing first, second and third or more AF ablation procedures. Further, we investigated whether LA dysfunction and LVZ are associated with recurrence after multiple procedures. Methods We retrospectively analyzed 460 patients undergoing AF ablation procedures including first, second and third or more sessions from January 2017 to October 2019 in our institute. Before each session, 256-slice MDCT was performed under sinus rhythm to measure pre-ablation LA emptying fraction (LAEF) as the representative of LA function. At the end of each session, we checked the presence of LVZ, which was defined as regions where bipolar peak-to-peak voltage was Results Out of 460 sessions, 295 were first (follow-up years: 1.5 [0.8, 2.0]), 134 were second (1.0 [0.5, 1.8]), and 31 were third or more sessions (1.2 [0.7, 2.0]). As the number of sessions increased, the recurrence rate was increased (19% vs. 31% vs. 61%, first vs. second vs. ≥third, P Conclusions As the number of sessions increased, the recurrence rate was increased. The prevalence of LA dysfunction and LVZ was high in patients requiring multiple ablation procedure. LA dysfunction and LVZ possibly reflect arrhytmogenic substrate causing recurrence of ablation-refractory AF. We should carefully consider repeated AF ablation in patients with severe LA dysfunction and extensive LVZ. Figure 1 Funding Acknowledgement Type of funding source: None

Background Successful restoration of sinus rhythm (SR) by catheter ablation (CA) for persistent atrial fibrillation (AF) improves cardiac function, resulting in decrease of plasma brain natriuretic peptide (BNP) level. The exact significance and prognostic implications of this change have yet to be determined. Purpose To examine the impact of pre- and post-procedural BNP level on the clinical outcome after CA in patients with persistent AF and reduced left ventricular ejection fraction (LVEF). Methods Out of 242 patients with LVEF Results All patients successfully restored SR at the end of CA. Within 3 months of a blanking period (BP), improvement of LVEF (from 39±10% to 65±12%, p55.5 pg/ml (n=50) than the others (50% vs. 29%; HR, 3.99; 95% CI, 2.07–7.68; p Conclusions Not pre-procedural but post-procedural BNP level early after CA predicted the future clinical outcome in patients with persistent AF and reduced LVEF. Decreased but still elevated BNP level after restoration of SR would identify the residual risk for developing unfavorable outcome.

Background Serum Brain Natriuretic Peptide (BNP) level is associated with various cardiovascular events. Because elevated BNP level reflects increased left ventricular end-diastolic pressure and LA pressure promoting left atrial (LA) remodeling, BNP level might be associated with the extent of arrhythmogenic substrate in patients with atrial fibrillation (AF). We hypothesized that elevated BNP level has impact on outcome after catheter ablation (CA) for AF. Purpose We investigated the impact of baseline BNP level on outcome after multiple CA for paroxysmal atrial fibrillation (PAF), and assessed the association between baseline BNP level and extent of LA remodeling. Methods This was a retrospective, single-center observational study. A total of 287 patients who underwent CA for PAF in our institute from March 2012 to March 2014. All patients had dataset of baseline BNP level and LA volume measured by multi-detector computed tomography (MDCT) in sinus rhythm. First we performed receiver operating characteristic (ROC) analysis for recurrence after multiple CA and obtained the best cut-off value of BNP. Patients were divided into Low BNP and High BNP group based on BNP cut-off value, and AF-free survival was analyzed with log-rank test. To assess the impact of BNP level on recurrence, multivariate Cox regression model were performed. Finally, we assessed the extent of baseline LA remodeling in low BNP and high BNP group. Results During follow-up period, AF recurred in 65/287 patients (26.2%) after multiple CA procedure (follow up 3.4 [2.2, 4.0] years, total number of sessions: 1.39±0.63). Patients with recurrence had greater baseline BNP than those without recurrence (99.8 pg/mL [30.0, 128] vs. 60.7 pg/mL [17.3, 80.8], recurrence vs. no-recurrence, P Conclusion Baseline serum BNP level was associated with recurrence after multiple procedures for PAF. The baseline extent of LA remodeling was greater in High BNP than in Low BNP. Elevated BNP level might reflect the severe LA remodeling causing ablation-refractory AF even after multiple CA. The preoperative assessment of BNP might be helpful for prediction of multiple CA outcome.