Abstract Background The Variable-Loop Circular Catheter (VLCC) is a bidirectional multi-electrode catheter capable of electroanatomical mapping and pulsed field energy delivery for the treatment of atrial fibrillation (AF). Objective to compare Grid projected annotation (GRID) versus projected Ablation tags (ABLt) in predicting lesion area coverage for Pulmonary Vein Isolation (PVI) with VLCC. Methods Consecutive AF patients undergoing PVI with VLCC were prospectively enrolled in our centre between April 2024 and October 2025. Ablation area was visualized using projected 1 mm³ grid points (GRID) or 2 mm projected ablation tags (ABLt) corresponding to each electrode of the VLCC for every ablation. Bipolar voltage maps were performed with VLCC to quantify the lesion areas per PV segment (10-segment model) after PVI. Anatomical maps with GRID or ABLt annotation without voltage data were used to calculate predicted lesion area. The predictive capability of GRID/ABLt was calculated using the formula GRID or ABLt Area in Low Voltage Area/ Total Low Voltage Area and expressed as a percentage. Results We enrolled 65 patients (64.5 ± 9.5 years, 55.4% males, 15.3% Persistent AF) and a total of 258 PVs. All patients underwent PVI. Median procedural time was 58 min (45-75), dwelling time 30 min (25-50) and fluoroscopy time 4 min (3-7). GRID and ABLt annotation were consistent with PV lesion area resulting in a Pearson’s correlation coefficient of 0.91 (p < 0.0001) and 0.82 (p < 0.0001), respectively. GRID showed a higher predictive capability of overall PV lesion area compared to ABLt (95.8% vs 77.6%; p<0.0001) and also for all PV segments (p<0.01) (Figure 1). GRID annotation demonstrated a lower bias (0.031) and narrow limits of concordance (0.421- -0.344) compared to ABLt demonstrated a higher bias (-0.33) and larger limits of concordance (0.356 - −1.016). Conclusions GRID showed a higher predictive capability of PV lesion area compared to ABLt

Pulsed field ablation (PFA) uses high-intensity electric fields to create myocardial lesions and may potentially interact with cardiac implantable electronic devices (CIEDs). This multicenter study evaluated the effects of different PFA technologies on electrical integrity and device-related complications in patients undergoing left- and right-sided atrial ablation. Consecutive patients with CIEDs undergoing catheter ablation with 4 PFA technologies were included. CIED interrogation was performed at baseline, after ablation, and at ≥ 3-month follow-up. Study endpoints were electrical integrity, defined as changes in sensing, pacing threshold, or impedance, and clinically relevant PFA-related CIED malfunction. Real-time device monitoring was performed in a subgroup to assess electromagnetic interference (EMI). A total of 157 patients were included. PFA was performed using a pentaspline catheter in 110 patients, a lattice-tip catheter in 26, a variable-loop circular catheter in 16, and a circular array catheter in 5. No significant changes in lead parameters were observed immediately after ablation or at 3-month follow-up, including in patients undergoing right atrial PFA. PFA was frequently associated with EMI-related oversensing (93

BACKGROUND:Atrial fibrillation (AF) markedly impairs quality of life (QoL) and increases health care burden. Long-term outcomes of catheter ablation (CA) using continuous rhythm monitoring remain undercharacterized. OBJECTIVES:The goals of this study were to assess atrial tachyarrhythmia burden (ATaB) using implantable loop recorder (ILRs) before and up to 4 years after CA and to examine the association between ATaB reduction and QoL. In an exploratory proof-of-concept analysis, we evaluated whether simulated intermittent monitoring (burden-by-sampling [BBS]) can approximate ILR-derived ATaB. METHODS:In this single-center prospective cohort, 165 patients with paroxysmal or persistent AF underwent first-time CA after preablation ILR insertion. ATaB (percentage time in AF/atrial tachycardia) was continuously recorded for up to 4 years. Annual QoL assessments used the Short Form-36 Health Survey and an AF-specific symptom questionnaire. Retrospective BBS simulation sampled ILR data at varying frequencies to explore intermittent monitoring performance. RESULTS:The median follow-up period was 40.9 (38.3-42.8) months. The median ATaB declined from 15% (0%-100%) to 0% (0%-22.5%) (P < .001). In the recurrence subgroup (n = 76, 46%), ATaB decreased from 93% to 0.45% (0.09%-8.2) (P < .001); >90% of patients achieved ≥75% reduction. QoL improved significantly at 1 year and remained stable, although Short Form-36 Health Survey physical health scores were not consistently significant beyond 1 year. BBS performance improved with increased sampling frequency but remained exploratory. CONCLUSION:CA produces a durable, substantial reduction in ATaB over 4 years, with a sustained QoL benefit. These findings challenge binary definitions of ablation success and support burden-based, patient-centered end points. Exploratory BBS simulations suggest potential for intermittent monitoring but require prospective validation.

BACKGROUND:In vivo electroanatomic mapping has enabled functional characterization of the human sinoatrial node (SAN), yet precise localization of SAN exit zones (SAN-EZs) and preferential conduction pathways-particularly along the Bachmann bundle (BB)-remains challenging without direct anatomic validation. OBJECTIVE:This study aimed to establish a translational framework integrating human in vivo peak frequency (PF) mapping with preclinical anatomic and histologic validation of the SAN-BB conduction axis. METHODS:High-density endocardial electroanatomic mapping with PF analysis was performed in patients with inappropriate sinus tachycardia, sick sinus syndrome, and normal SAN function. Emphasis maps combining local activation time and PF were used to identify the SAN-EZ and preferential conduction pathways. To address anatomy, complementary preclinical studies were performed using contrast-enhanced micro-computed tomography, 3-dimensional reconstruction, and histology of donor human hearts, focusing on BB microstructure, insertion sites, and myocyte orientation. Frequency analysis was additionally applied to preclinical hearts to compare the BB with the surrounding right atrial myocardium. RESULTS:In vivo PF mapping reliably identified the SAN-EZ and preferential conduction pathways using a 350-450 Hz frequency band. Patients with sick sinus syndrome exhibited reduced SAN-EZ overlap and fewer superior and septal pathways. Preclinical micro-computed tomography and histology in cadaveric human hearts confirmed the anatomic substrate underlying septal conduction. Frequency analysis of swine hearts revealed higher dominant frequencies within the BB than adjacent right atrial myocardium, supporting in vivo findings. CONCLUSION:By integrating human functional mapping with preclinical anatomic and histologic validation, this study provides a translational framework for PF-based identification of the SAN-EZ and BB-mediated conduction.

BACKGROUND AND AIMS:Stroke and systemic embolism are recognized but poorly characterized complications of atrial fibrillation (AF) and left atrial flutter (AFL) catheter ablation. Their incidence, outcomes, and procedural associations remain insufficiently defined. METHODS:Retrospective global registry was initiated by the European Heart Rhythm Association Scientific Committee. A secure database captured data from ablation centres worldwide on general AF and left AFL ablation activity, as well as detailed information on patients with symptomatic embolic events between 2017 and 2024. RESULTS:Overall, 204 centres reported 335 743 ablation procedures and 550 embolic events (incidence 0.16%). Centre-level rate ranged from 0% to 3.1%. Most events were cerebral (94%), followed by peripheral (5%), and combined (1%). Coronary air embolism accounted for 62% of all peripheral events. Intraprocedural events occurred in 93 patients (17%), within 72 h in 357 (78%) and beyond 72 h in 100 (22%); 128 cases (23%) were diagnosed after hospital discharge. Nonparoxysmal AF (0.23% vs 0.15%; P < .001), centre experience, and ablation energy source (radiofrequency, 0.16%; cryoballoon, 0.16%; pulsed field ablation, 0.25%; laserballoon, 0.88%; P < .001) were associated with embolic risk. Median NIHSS score after stroke was 4 (interquartile range, 2-9). Three-month follow-up was available for 518 patients with embolism (95%): 181 (35%) had sequelae and 16 (3%) died. CONCLUSIONS:Symptomatic embolic events are infrequent but associated with significant morbidity and mortality. Most events occur early, though a substantial proportion arise later. Higher event rates were observed with laser and possibly with pulsed field ablation. A greater centre experience was associated with a lower embolism incidence.

BACKGROUND:The safety and effectiveness of the variable loop circular catheter (VLCC) pulsed field ablation (PFA) system was shown in atrial fibrillation (AF) registrational trials. OBJECTIVE:Assess acute safety and effectiveness of first-time pulmonary vein isolation (PVI) with the VLCC in standard clinical practice in the VARIPURE substudy of the ongoing, prospective, multicenter, observational SECURE postmarket follow-up study. METHODS:Data were extracted from Electronic Data Capture and the CARTONET data analytics software. Primary safety was the incidence of primary adverse events related to the VLCC and/or procedure. Primary effectiveness was acute procedural success, confirmed by electrical isolation of all targeted PVs. RESULTS:Among 1022 AF patients (mean age 64.9 years, 63.3% male, 63.5% paroxysmal AF; mean CHA2DS2-VASc 2.2; 22 European centers, 74 operators), 29.5% underwent ablations beyond the PVs (PVI+). The mean ± standard deviation procedure, left atrial dwell, and fluoroscopy times were 60.1 ± 21.9, 38.0 ± 15.6, and 5.2 ± 5.6 minutes, respectively. The primary adverse event rate was 0.8%, with no stroke, cerebrovascular accident, or transient ischemic attack. No ST elevation, coronary spasm, or acute kidney injury were reported. Acute reconnection was assessed per physician preference in a subset of patients (18.5% [78/421]). Acute PVI was achieved in 99.8% of patients. Using CARTONET (868 cases), the recommended workflow of 16-28 ablations for PVI was followed in 83.1% of patients with a 4-PV anatomy. CONCLUSION:In the largest real-world VLCC yet, PFA with the VLCC exhibits favorable safety, high acute efficacy, procedural efficiency, and recommended workflow adherence. Results may provide a strong foundation for future studies of this PFA technology upon 12-month follow-up completion. CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT04750798 (https://clinicaltrials.gov/study/NCT04750798).

AIMS:Atrial fibrillation (AF) ablation by pulmonary vein isolation (PVI) and left atrial appendage closure (LAAC) are increasingly performed as standalone procedures. Given that PVI and LAAC share the same access route, a combined approach of pulsed field ablation (PFA)-based PVI and LAAC might be beneficial. The COCONUT study focused on safety, efficacy, and outcomes combining PVI by PFA with LAAC in one procedure. METHODS:This is a retrospective, multinational registry study. The primary endpoints were the following: (1) primary safety endpoint: serious adverse events; and (2) primary efficacy endpoint: success of PVI and LAA closure defined as the ability to isolate all pulmonary veins and the successful closure of the LAA. For secondary endpoints, peri-procedural data and follow-up data were collected. RESULTS:A total of 155 patients from 22 centres of nine European countries were treated by concomitant pentaspline catheter PFA-based PVI and LAAC. The mean CHA2DS2-VA score was 3.1 ± 1.4. The primary efficacy endpoint was achieved at 97.4% with successful PVI at 100% and successful LAAC in 151/155 patients (97.4%). The primary safety endpoint was observed in 3/155 patients (1.9%). Transoesophageal echocardiography and/or CCTA 67 ± 26 days after the procedure showed no device embolization and no device-related thrombus, 24/151 (15.9%) patients showed peri-device gaps of <5 mm while gaps of >5 mm have been observed in 3/151 (2.0%). Among 137/155 patients with available arrhythmia, a follow-up >6 months at 78.1% showed sinus rhythm. CONCLUSION:In this large multicentre study, concomitant PFA-based AF ablation and LAA closure proved to be feasible, effective, and safe and overall procedure duration was short.

BACKGROUND:Reversible pulsed field ablation (PFREV) can temporarily block cardiomyocyte conduction, potentially identifying critical target sites before creating definitive lesions. However, PFREV local capture might interfere with the tachycardia mechanism. The aim of the study was to characterize the responses of nontriggered PFREV pulses to serve as a novel clinical mapping tool in reentrant atrial flutter. METHODS:PFREV pulses were delivered in and outside of the circuit using a 9-mm lattice-tip catheter in 30 reentrant atrial tachycardias in 26 patients. The presence of local capture and responses to PFREV pulses was characterized. RESULTS:Out of 163 PFREV pulses analyzed, 56 (34.4%) showed atrial capture and propagation. Propagated versus Nonpropagated PFREV cohorts were compared. The coupling interval of propagated PFREV pulses was significantly longer (195.3±69.2 msec versus 98.9±77.2 msec; P<0.001). Globally, 4 responses were observed: tachycardia termination (11.0%), stable tachycardia cycle length (TCL) prolongation (9.8%), transient irregular TCL variations (3.1%), and no change in activation sequence and TCL (76.1%). Propagation was only associated with irregular TCL variations (8.9% versus 0%, P=0.002). Tachycardia termination or TCL prolongation occurred only when PFREV was delivered in the reentry circuit (100% specificity). Termination occurred exclusively in the critical isthmus (100% specificity regardless of propagation), and stable TCL prolongation occurred in 93.8% and 6.2% of the cases in the isthmus and outer loop, respectively (100% specificity for nonpropagated and 83.3% specificity for propagated PFREV to localize the isthmus). Sensitivity of termination or stable TCL prolongation for identifying the critical isthmus was moderate (38.8%) and influenced by isthmus width (11.7±1.7 mm versus 22.9±2.1 mm; P<0.001). Reproducibility of PFREV pulses, determined by consecutive pulses delivered at the same site producing identical responses, was high (82.9%). CONCLUSIONS:PFREV mapping is a novel, feasible, and reproducible tool for identifying critical sites in reentrant atrial tachycardia with narrow isthmuses that may be improved through optimized triggering and dose titration.

BACKGROUND:Patients undergoing catheter ablation (CA) for persistent atrial fibrillation (PsAF) experience high rates of AF recurrence. Direct current cardioversion (DCCV) is often performed prior to CA, with variable post-DCCV duration of sinus rhythm (SR). OBJECTIVE:We aimed to determine whether shorter SR duration after DCCV is associated with AF recurrence after subsequent CA. METHODS:We performed an international multicentre retrospective study of patients undergoing first-time CA for PsAF between 2015 and 2024 with a prior DCCV. SR duration after the last DCCV preceding CA was recorded. The primary outcome was freedom from atrial arrhythmia after CA (after a 56-day postablation blanking period). RESULTS:938 patients undergoing first-time CA for PsAF were identified from six centres and categorised by post-DCCV SR duration: <7 days (group 1, n=212); 7-31 days (group 2, n=236); and >31 days (group 3, n=490). Over median post-CA follow-up of 511 days, 512 patients (55%) experienced atrial arrhythmia recurrence. There was no significant between-group difference in freedom from atrial arrhythmia (log-rank p=0.10). When analysed as a continuous variable in a Cox regression model, there was no association between post-DCCV SR duration and time to first recurrence of atrial arrhythmia (HR per 10-day increment 1.00, 95% CI 1.00 to 1.01, p=0.07). In secondary analyses, there were significantly more blanking period arrhythmias in groups 1 and 2 compared with group 3 (both pairwise p<0.001), and presentation for CA in persistent atrial arrhythmia was associated with a time-dependent increased risk of atrial arrhythmia recurrence compared with presentation in SR. CONCLUSION:In this large multicentre cohort, shorter duration of SR after DCCV was associated with blanking period arrhythmia after subsequent CA, but we did not find evidence of an association with long-term AF recurrence. Clinicians should consider these findings when making decisions regarding suitability for CA or predicting long-term CA success.

Physiological pacing of the atrium, specifically targeting the Bachmann bundle area (BBA), has been associated with improved interatrial conduction and reduced atrial arrhythmia risk. The Bachmann bundle (BB) is the principal interatrial conduction tract, yet its electrophysiological definition in humans remains incompletely characterized. This study aimed to describe the electrogram features of the BBA using 3D electroanatomical-mapping (EAM) with peak-frequency (PF) analysis during atrial lead implantation. All patients undergoing dual-chamber pacemaker implantation with the atrial lead positioned in the BBA were included. Right atrial mapping was performed using either a quadripolar or the HD Grid catheter. PF maps were created and PFs at the targeted site were measured before and after lead positioning. Procedural parameters, P-wave duration (PWD) and pacing thresholds were analyzed. Twelve consecutive patients undergoing dual-chamber pacemaker implantation with the atrial lead positioned in the (BBA) were prospectively studied. The optimal PF band for BBA localization was 400–500 Hz (AUC = 0.83, sensitivity 87

Background:In patients with symptomatic permanent atrial fibrillation (AF) who are not candidates for rhythm control, atrioventricular node (AVN) ablation followed by ventricular pacing "ablate-and-pace" offers reliable rate control and symptom relief. Conventional transvenous systems are effective but associated with lead- and pocket-related complications. Leadless pacemakers represent a promising alternative, yet comparative data in this setting remain scarce. The aim is to compare clinical outcomes of leadless vs. transvenous single-chamber pacemakers in patients undergoing AVN ablation for permanent AF. Methods:We conducted a retrospective, multicenter study (LEAD-AP) of 168 consecutive patients undergoing ablate-and-pace between 2,017 and 2024 across four European centers. Patients received either a leadless pacemaker (n = 56) or a conventional transvenous VVI pacemaker (n = 112). The primary efficacy endpoint was the composite of all-cause mortality, cardiovascular mortality, AF-related hospitalizations, unplanned visits and device-related hospitalizations or reinterventions. The secondary efficacy endpoint was device-related hospitalizations or reinterventions. The primary safety endpoint was acute complications within 30 days. Results:Patients in the leadless group more frequently underwent a single-step ablate-and-pace strategy (96.4% vs. 10.9%, p < 0.001), resulting in shorter hospitalization (1.1 days ± 3.1 vs. 5.7 days ± 2.2, p = 0.008). At 24 months of follow-up, there was no statistically significant difference between patients with leadless pacemaker vs. standard single-chamber VVI pacemaker in the event-free survival for the clinical efficacy endpoint (82.1% vs. 80.4% Log-Rank p = 0.29). Conclusions:Leadless pacemakers provide comparable safety and efficacy to transvenous systems in ablate-and-pace patients, while enabling shorter hospitalization through a streamlined single-step approach.