Abstract Background: Pulmonary vein (PV) reconnection and the onset of non-PV triggers is frequently the cause of atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA). The effectiveness of using isoproterenol for unmasking dormant conduction and non-PV-triggers during AF RFCA and its effect on improving procedural and clinical outcomes is still controversial. Objective: To evaluate the effectiveness of isoproterenol for unmasking dormant conduction and non-PV-triggers during RFCA for paroxysmal AF (PAF) and its effects on procedural and long-term clinical outcomes. Methods: In this prospective multicenter cohort from the REAL-AF registry, patients who underwent RFCA for PAF with and without isoproterenol administration from January 2018 to May 2023 were included. The primary efficacy outcome was freedom from all-atrial arrhythmias at 12-month follow-up. Secondary outcomes included procedural and long-term clinical outcomes, and procedure-related complications. Results: A total of 1102 patients were included (isoproterenol=325 vs. control=777) (mean age 66.73±10.19 years; 53.05% male). There were no differences in baseline characteristics between the groups. Dormant conduction/non-PV triggers with isoproterenol was observed in 10.2% of the patients. Isoproterenol administration was associated with increased procedural times (109 (83-137.5) vs. 96 (74-122), p=0.002), and decreased rates of first-pass PV isolation (74.84% vs. 80.14%, p=0.007). There were no differences in freedom from all-atrial arrhythmias (HR 0.87, 95% CI [0.61-1.24], p=0.4) or long-term clinical outcomes at 12 months of follow-up between the groups. Conclusion: In patients undergoing RFCA for PAF, the use of isoproterenol was associated with increased procedural times and more extensive ablation, without improved clinical outcomes at 12-month follow-up.

Background: High-frequency low-tidal-volume (HFLTV) ventilation is a safe and cost-effective strategy that improves catheter stability, first-pass pulmonary vein isolation, and freedom from all-atrial arrhythmias during radiofrequency catheter ablation (RFCA) of paroxysmal and persistent atrial fibrillation (AF). However, the incremental value of adding rapid-atrial pacing (RAP) to HFLTV-ventilation has not yet been determined. Objective: To evaluate the effect of HFLTV-ventilation plus RAP during RFCA of paroxysmal AF on procedural and long-term clinical outcomes compared to HFLTV-ventilation alone. Methods: Patients from the REAL-AF prospective multicenter registry, who underwent RFCA of paroxysmal AF using either HFLTV+RAP (500-600 msec) or HFLTV ventilation alone from April 2020 to February 2023 were included. The primary outcome was freedom from all-atrial arrhythmias at 12-month follow-up. Secondary outcomes included procedural characteristics, long-term clinical outcomes, and procedure-related complications. Results: A total of 545 patients were included in the analysis (HFLTV+RAP=327 vs. HFLTV=218). There were no significant differences in baseline characteristics between the groups. No differences were observed in procedural (HFLTV+RAP 74 [57-98] vs. HFLTV 66 [53-85.75] min, p=0.617) and RF (HFLTV+RAP 15.15 [11.22-21.22] vs. HFLTV 13.99 [11.04-17.13] min, p=0.620) times. Both groups showed a similar freedom from all-atrial arrhythmias at 12-month follow-up (HFLTV+RAP 82.68% vs. HFLTV 86.52%, HR=1.43, 95% CI [0.94-2.16], p=0.093). There were no significant differences in freedom from AF-related symptoms (HFLTV+RAP 91.4% vs. HFLTV 93.1%, p=0.476) or AF-related hospitalizations (HFLTV+RAP 98.5% vs. HFLTV 97.2%, p=0.320). Procedure-related complications were low in both groups (HFLTV+RAP 0.6% vs. HFLTV 0%, p=0.247). Conclusion: In patients undergoing RFCA for paroxysmal AF, adding RAP to HFLTV-ventilation was not associated with improved procedural and long-term clinical outcomes.

Background: Intracardiac echocardiography (ICE) is increasingly used during left atrial appendage occlusion (LAAO) as an alternative to transesophageal echocardiography (TEE) Aim: To evaluate the impact of ICE vs. TEE guidance during LAAO on procedural characteristics and acute outcomes, as well the presence of peri-device leaks and residual septal defects during follow-up. Methods: All studies comparing ICE-guided vs. TEE-guided LAAO were identified. The primary outcomes were procedural efficacy and occurrence of procedure-related complications. Secondary outcomes included lab efficiency (defined as a reduction in in-room time), procedural time, fluoroscopy time, and presence of peri-device leaks and residual interatrial septal defects (IASD) during follow-up. Results: Twelve studies (n=5637) were included. There were no differences in procedural success group (98.3% vs. 97.8%; OR 0.73, 95% CI 0.42-1.27, p=0.27; I2=0%) or adverse events (4.5% vs. 4.4%; OR 0.81 95% CI 0.56-1.16, p=0.25; I2=0%) between the ICE-guided and TEE-guided groups. ICE guidance reduced in in-room time (mean-weighted 28.6-minute reduction in in-room time) without differences in procedural time or fluoroscopy time. There were no differences in peri-device leak (OR 0.93, 95% CI 0.68-1.27, p=0.64); however, an increased prevalence of residual IASD was observed with ICE-guided vs. TEE-guided LAAO (46.3% vs. 34.2%; OR 2.23, 95% CI 1.05-4.75, p=0.04). Conclusion: ICE guidance is associated with similar procedural efficacy and safety, but could result in improved lab efficiency (as established by a significant reduction in in-room time). No differences in the rate of periprocedural leaks were found. A higher prevalence of residual interatrial septal defects was observed with ICE guidance.

Introduction: Some patients suffer recurrent syncope following cardioneuroablation (CNA) for vasovagal syncope (VVS), yet no cases of repeat CNA have been described in detail. Methods and Results: Our present patient suffered a recurrence seven months following successful CNA and wished for a repeat CNA. Pre-procedurally, she lacked an atropine response. During CNA, high-frequency stimulation (HFS) at ganglionated plexi (GP) would not trigger cardioinhibitory events. Ablation was delivered based on anatomy and fractionation mapping, producing characteristic tachycardia at 2 GP sites. Conclusion: Repeat CNA is feasible and safe, and characterized by unique physiology.

Pulsed-Field Ablation: What Are the Unknowns and When Will They Cease to Concern Us?Nathaniel A. Steiger* and Jorge Romero, MD*