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Background: Pulsed-field ablation (PFA) is a nonthermal method for achieving selective cell death with little inflammation response. However, there are no reports of PFA for septal reduction therapy (SRT)., Objective: The purpose of this study was to investigate the effectiveness and safety of PFA for SRT., Methods: A novel transvenous intraseptal PFA method with 3-dimensional (3D) guidance was introduced in Yorkshire pigs. Electrocardiographic parameters, transthoracic echocardiography, and histopathology were used to evaluated., Results: The maximum injury diameter of intramyocardial PFA increased with electric field intensity. After PFA, bipolar electrogram amplitude and pacing threshold measured by the PFA electrodes significantly decreased (F = 6.945, P = .007) or increased (F = 5.842, P = .024), respectively. In the ablated septal region, motion amplitude and systolic wall thickening rate significantly decreased and remained at low levels (motion amplitude: F = 20.793, P = .000; systolic wall thickening rate: F = 14.343, P = .000); however, septal thickness did not significantly change after PFA (F = 1.503, P = .248). Histologic examination showed specific cardiomyocyte death with gradually increased hyperchromatic cytoplasm and nuclear pyknosis, without obvious inflammatory cell infiltration in acute phase. TUNEL stain for fragmented DNA showed extensively positive in the ablation region 24 hours after PFA. During PFA, no sustained ventricular arrhythmia or atrioventricular conduction block occurred., Conclusion: A novel intraseptal PFA method with 3D guidance was described. Intraseptal PFA resulted in effective myocardial injury and local hypokinesis without significant acute edema. Histologic examination showed widely programmed cardiomyocyte death with little inflammatory cell infiltration., Competing Interests: Disclosures The authors have no conflicts to disclose., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Purpose: Precise automatic annotation of local activation time (LAT) is crucial for rapid high-density activation mapping in arrhythmia. However, it is still challenging in voltage-transitional areas where local low-amplitude near-field potentials are often obscured by large far-field potentials. The aim of this study was to explore the viability and validity of automatic identification of the earliest activation (EA) in idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT VAs) using a novel Lumipoint algorithm., Methods and Results: Twenty-seven patients with RVOT VAs were mapped with Rhythmia mapping system. Lumipoint algorithms were applied to reannotate the initial activation regions retrospectively. The results showed that LATs were reannotated in 35.0 ± 11.4% points in the initial activation area from bipolar activation breakout time (BBO) to the its 40 ms earlier timepoint. The automatically determined bipolar earliest activation time after Lumipoint reannotation (BEAT-lu: - 111.26 ± 12.13 ms) was significantly earlier than that before (BEAT: - 108.67 ± 12.25 ms, P = 0.000). Compared with manually corrected earliest activation time (EAT), the difference between EAT and BEAT-lu (D EAT-BEAT-lu : 6 (2-7) ms) was significantly smaller than that between EAT and BEAT (D EAT-BEAT /D EAT-UEA : 7 (4-11) ms, P = 0.000). The incidence of EAT and BEAT-lu being the same site was significantly higher than that between EAT and BEAT (48.15% vs 18.52%, P = 0.021)., Conclusions: RVOT VAs often originate from voltage-transitional zone, and automatic annotation of LAT usually located at later high-amplitude far-field potential. Lumipoint algorithms could improve the accuracy of LAT automatic annotation, and it was plausible to ablate RVOT VAs just according to the automatically annotated BEAS-lu.

Background: Epicardial to endocardial breakthrough (EEB) exists widely in atrial arrhythmia and is a cause for intractable cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL). This study aimed to investigate the electrophysiological features of EEB in EEB-related CTI dependent AFL., Methods: Six patients with EEB-related CTI-dependent AFL were identified among 142 consecutive patients who underwent CTI-dependent AFL catheter ablation with an ultra-high-density, high-resolution mapping system in three institutions. Activation maps and ablation procedure were analyzed., Results: A total of seven EEBs were found in six patients. Four EEBs (including three at the right atrial septum and one in paraseptal isthmus) were recorded in three patients during tachycardia. The other three EEBs were identified at the inferolateral right atrium (RA) during pacing from the coronary sinus. The conduction characteristics through the EEB-mediated structures were evaluated in three patients. Two patients only showed unidirectional conduction. Activation maps indicated that CTI-dependent AFL with EEB at the atrial septum was actually bi-atrial macro-reentrant atrial tachycardia (BiAT). Intensive ablation at the central isthmus could block CTI bidirectionally in four cases. However, ablation targeted at the inferolateral RA EEB was required in two cases. Meanwhile, local potentials at the EEB location gradually split into two components with a change in activation sequence., Conclusions: EEB is an underlying cause for intractable CTI-dependent AFL. EEB-mediated structure might show unidirectional conduction. CTI-dependent AFL with EEB at the atrial septum may represent BiAT. Intensive ablation targeting the central isthmus or EEB at the inferolateral RA could block the CTI bidirectionally., (© 2021 Wiley Periodicals LLC.)

Background: Atrial fibrillation (AF) is an important risk factor for thromboembolic events, for which catheter ablation represents an effective therapy for rhythm control. Intuitively, ablation may reduce the incidence of thromboembolism, but data is quite limited., Hypothesis: Catheter ablation was associated with the fewer risk of thromboembolism compared with nonablation in patients with AF., Methods: A systematic search was performed in PubMed, EMBASE, the Web of Science, and the Cochrane Library from inception to September 2019. Random-effects model was used to estimate the risk ratios (RR) for the thromboembolic events between the ablation and nonablation groups., Results: Twenty-five studies (12 randomized controlled trials and 13 observational studies) with 104 687 participants were included. Pooled analysis suggested that ablation was associated with a 35% lower risk of total thromboembolic events compared to nonablation group (RR = 0.65; 95% CI, 0.51-0.82; P = .0003). When separated into early-phase (<30 days) and late-phase (>30 days) events, ablation was associated with an increased early-phase thromboembolism (RR = 1.96; 95% CI, 1.35-2.83; P = .0004) but a decreased late-phase thromboembolism (RR = 0.75; 95% CI, 0.63-0.90; P = .002). Subgroup analysis according to different study types found similar results were found in observation studies, but not in RCT studies because the sample size was too small to be conclusive., Conclusions: In patients with AF, catheter ablation was associated with a fewer risk of overall and late-phase thromboembolism in comparison with nonablation. However, over the early postoperative period, catheter ablation was associated with the double higher risk of thromboembolic events., (© 2020 The Authors. Clinical Cardiology published by Wiley Periodicals, Inc.)

Atrial fibrillation (AF), the most common cardiac arrhythmia, is a major risk factor for thromboembolic events, especially ischemic stroke. Catheter ablation is an effective method to maintain sinus rhythm in patients with AF. Although some observational studies have shown a relatively lower stroke rate after catheter ablation, whether catheter ablation can reduce the thromboembolic risk in patients with AF remains unclear. We aim to perform a systematic review to determine whether catheter ablation can prevent thromboembolism in patients with AF.PubMed, Embase, the Web of Science, and the Cochrane Library will be searched from January 2000 to the present for randomized controlled trials (RCTs) and non-randomized studies on catheter ablation in patients with AF. Other relevant sources, such as the references and conference proceedings, will also be manually retrieved. All studies will be limited to publication in English. The primary outcome will be thromboembolic events, including stroke, transient ischemic attack, and systemic embolic events. Study screening, data collection, and study quality assessment will be independently performed by 2 researchers. Disagreements will be resolved through team discussion or consultation with a third arbitrator. The risk of bias will be appraised using the Cochrane Collaboration tool and the Newcastle-Ottawa scale according to the different study designs, and a meta-analysis will be performed using RevMan V.5.3 software. The results will be presented as risk ratios and 95% confidence intervals for dichotomous data and continuous outcomes.Catheter ablation is an effective method to cure atrial fibrillation and maintain sinus rhythm. Although it is intuitive that if AF is eliminated, the thromboembolism in the heart would be abolished, and sequently the incidence of thromboembolic events would be decreased, this in fact has not yet been clarified. This systematic review and meta-analysis will be performed with the aim of comprehensively identifying studies that have reported the impact of AF ablation on thromboembolic events in patients with non-valvular AF by comparing an ablation group and non-ablation group. These outcomes will not only produce useful evidence-based data regarding the influence of catheter ablation on thromboembolic events in patients with AF but will also provide some guidance regarding anticoagulation regimens in patients who have undergone catheter ablation.

Introduction: Right ventricular outflow tract ventricular arrhythmias (RVOT VAs) often originate in the voltage‐transitional zone. The target electrogram could be compromised by the architecture of the roving catheter. Mini‐electrodes could improve the mapping resolution, especially in low‐voltage areas. The aim was to assess the electrophysiological characteristics of the earliest activation site (EAS) of RVOT VAs during mapping using mini‐electrodes. Methods and Results: Twenty‐seven patients with RVOT‐type VAs were mapped using Orion mini‐electrodes and the Rhythmia mapping system. Bipolar and unipolar electrograms were analyzed and compared with conventional ablation catheter recordings. Twenty‐five patients (25 of 27) were successfully mapped and ablated at the RVOT. At the EAS, all 25 (100%) patients exhibited local sharp potentials (spiky potential) at the VAs, and 88% (22 of 25) individuals showed reverse late potentials in adjacent sinus beats on the bipolar mini‐electrode recordings. Related unipolar electrograms manifested 20% "q‐plateau‐QS," 76% "gross QS," and 4% "late QS" patterns related to spiky potential voltages and advanced times. Compared with electrograms recorded by ablation catheter, bipolar mini‐electrode recordings exhibited significantly shorter spiky potential durations (P = 0.001) and a significantly increased incidence of the reverse late potentials (P = 0.041). Unipolar mini‐electrode recordings had a lower incidence ratio of "late QS" patterns (P = 0.039). Conclusion: Compared with ablation catheter mapping, mini‐electrodes improved the mapping resolution of the EAS of RVOT VAs and exhibited shorter spiky potential durations and reduced incidence of "later QS" unipolar patterns. [ABSTRACT FROM AUTHOR]