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AimTo propose a standardized workflow for 3D-electroanatomical mapping guided pulmonary vein isolation in pigs.Materials and methodsDanish female landrace pigs were anaesthetized. Ultrasound-guided puncture of both femoral veins was performed and arterial access for blood pressure measurement established. Fluoroscopy- and intracardiac ultrasound-guided passage of the patent foramen ovale or transseptal puncture was performed. Then, 3D-electroanatomical mapping of the left atrium was conducted using a high-density mapping catheter. After mapping all pulmonary veins, an irrigated radiofrequency ablation catheter was used to perform ostial ablation to achieve electrical pulmonary vein isolation. Entrance- and exit-block were confirmed and re-assessed after a 20-min waiting period. Lastly, animals were sacrificed to perform left atrial anatomical gross examination.ResultsWe present data from 11 consecutive pigs undergoing pulmonary vein isolation. Passage of the fossa ovalis or transseptal puncture was uneventful and successful in all animals. Within the inferior pulmonary trunk 2–4 individual veins as well as 1–2 additional left and right pulmonary veins could be cannulated. Electrical isolation by point-by-point ablation of all targeted veins was successful. However, pitfalls including phrenic nerve capture during ablation, ventricular arrhythmias during antral isolation close to the mitral valve annulus and difficulties in accessing right pulmonary veins were encountered.ConclusionFluoroscopy- and intracardiac ultrasound-guided transseptal puncture, high-density electroanatomical mapping of all pulmonary veins and complete electrical pulmonary vein isolation can be achieved reproducibly and safely in pigs when using current technologies and a step-by-step approach.

Recurrent atrial tachycardia (AT) is a common phenomenon after catheter ablation for AF, particularly in the setting of additional substrate ablation, with many studies demonstrating gap-related macro re-entrant AT (predominantly mitral and roof dependent) to be the dominant mechanism. Although multiple inducible ATs after ablation of the clinical AT are commonly described at repeat procedures, the optimal ablation strategy, and procedural endpoints are unclear in this setting. A recent randomized study addressing the question of non-inducibility as a procedural endpoint demonstrated no additional benefits to the ablation of all induced, non-clinical ATs, but it was limited by small numbers and high rates of non-inducibility. Nevertheless, once ablation of the clinical AT has been successfully performed, ensuring durable linear block and PV isolation may be sufficient for the prevention of further AT. Durable linear block, particularly at the mitral isthmus, is difficult to achieve but may be facilitated by the real-time evaluation of lesion quality and contiguity and the novel technique of vein of Marshall ethanol infusion. Large-scale, randomized trials are needed, nonetheless, to fully assess the optimal ablation strategy in the setting of recurrent AT post-AF ablation. ispartof: FRONTIERS IN CARDIOVASCULAR MEDICINE vol:9 ispartof: location:Switzerland status: published

Treatment of symptomatic atrial fibrillation has seen important changes in the past decades. Advancements have especially been made in the field of non-pharmacological treatment of this disease. Patients in whom a rhythm control strategy is chosen the place of catheter ablation has become more frontline therapy in the past years. The procedure itself has also seen changes in technologies that can be used, either using point-by-point radiofrequency or one of the single-shot techniques. One of the major limitations that remain is that re-do procedures are often necessary due to incomplete pulmonary vein isolation and/or atrial fibrillation being initiated by other mechanisms than pulmonary vein triggers. Therefore, there is further need for developing ablation tools that reproducibly isolate the pulmonary vein transmurally. Furthermore, addressing the underlying conditions before and after catheter ablation has been shown to be of great importance. In this review, we will give an overview of the evolution of catheter ablation, highlight the latest technologies and their future endeavours, and lifestyle modifications are being discussed as part of the catheter ablation strategy.

Introduction Single-shot techniques such as cryoballoon and multipolar phased pulmonary vein ablation catheter (PVAC) are an alternative to the point-by-point radiofrequency method for atrial fibrillation (AF) ablation. However, there is a lack of data concerning sequential use of single-shot techniques, that is, for both the index and redo ablation. Aim To assess long-term outcomes of the 'single-shot techniques only' AF ablation strategy. Material and methods We analyzed all consecutive AF ablations performed over a 10-year period (2009-2019) in a center where a 'single-shot technique only' principle was followed from the start of the AF ablation program. Kaplan-Meier AF-free survival curves were calculated and complications were assessed on the basis of our prospectively maintained database. Results A total of 597 patients (62.4 ±12.5 years) with paroxysmal (78.1%) or persistent (21.9%) AF entered the study and 655 AF ablation procedures were performed. In 96.5% of redos (n = 58) a different technique (mostly PVAC) was used than for the index ablation (mostly cryoballoon). The Kaplan-Meier estimates of 1, 2 and 5 years freedom from AF were 78.2%, 69.2%, and 56.0%, for the index ablation, and 80.3%, 76.1% and 68.3%, for the redo, respectively. The minor and major complication rates were 8.1%, and 4.0%, respectively. Conclusions An AF ablation program based solely on sequential use of two different single-shot techniques for both index and redo procedures is safe and effective. These observations might have important practical implications for new operators/centers starting AF ablation programs and for use of single-shot techniques for redo procedures.

Pulmonary vein stenosis (PVS) is a rare, severe, and potentially fatal complication most often arising from pulmonary vein ablation for medication refractory, symptomatic, and permanent atrial fibrillation. At present, the optimal approach for the management of PVS remains to be defined. Here, we describe a unique case of bifurcation pulmonary venoplasty and stenting in a patient with recalcitrant PVS after surgical reconstruction of her pulmonary veins. To our knowledge, this is the first such report of its kind.

Background: Atrial fibrillation (AF), a common arrhythmia in clinical practice, is associated with a high rate of complications and an increased risk for thromboembolic events. Pulmonary vein ablation is a new therapeutic option to cure AF; however, it remains associated with a high rate of recurrence. In this study we aimed to identify the clinical characteristics and imaging-based features that may predict the risk of recurrence after pulmonary veins ablation in atrial fibrillation. Materials and method: Twenty-four patients with paroxysmal and persistent AF, who underwent radiofrequency catheter ablation and a 12-month follow-up were included in the study. Group 1 included 8 patients with AF recurrence, and group 2 included 16 patients with no AF recurrence. In all cases, cardiovascular risk factors, ejection fraction, left atrial diameter, atrial volumes, and epicardial fat volume were analyzed. Results: CT analysis revealed that patients with AF recurrence presented a significantly larger mean index of left atrial volume (59.57 ± 8.52 mL/m2 vs. 49.99 ± 10.88 mL/m2, p = 0.04), right atrial volume (58.94 ± 8.37 mL/m2 vs. 43.21 ± 6.4 mL/m2, p Conclusion: Left atrial diameter, indexed atrial volumes, and epicardial fat volume may be used as factors to identify patients at risk for developing recurrence after pulmonary vein ablation.

Background Atrial fibrillation (AF) recurrence rate still stands between 40% and 50%, causing complications. Therefore, early diagnosis of AF recurrence is needed for prompt treatment, thus morbidity and mortality could be reduced and quality of life could be improved. Aim Determine predictive value of electrocardiogram and its findings towards AF recurrence in population who have underwent intervention. Methods Systematic review and meta-analysis was conducted according to PRISMA statement. Six reviewers searched studies from PubMed, ProQuest, ScienceDirect, and EBSCO from inception to June 2021 with primary outcome of AF recurrence. Data was appraised and processed using random effects or fixed effects model with the outcome of mean difference (MD) or odds ratio (OR) with 95%-confidence interval (95% CI). Results Thirty included studies involving 5,490 subjects were found good in terms of quality assessment. AF recurrence on patients underwent cardioversion was more likely found in patients with larger P-wave duration (OR = 2.90; 95% CI [1.47, 5.74]; p = 0.01) and P-wave dispersion (MD = 12.67 ms; 95% CI [10.73, 14.62]; p Conclusion P-wave and P-wave dispersion were considered as predictive factor for AF recurrence in patients underwent cardioversion and PVI.

Background Improving the quality of life (QoL) is one of the main purposes of catheter ablation (CA) of persistent atrial fibrillation (AF). QoL improvement in persistent AF patients has not been fully clarified. The EARNEST-PVI trial was a multi-center randomized trial comparing clinical outcomes of pulmonary vein isolation (PVI) alone and more intensive ablation in addition to PVI including complex fractionated atrial electrogram (CFAE) and linear ablation (PVI plus). Purpose To investigate the QoL change after persistent AF ablation and the differences between the PVI-alone strategy and the PVI plus strategy. Methods In the EARNEST-PVI trial, patients with persistent AF who underwent an initial catheter ablation (n=512) were randomly assigned in a 1:1 ratio to either PVI alone or PVI plus. Quality of life was assessed at baseline and at 12 months after ablation for AF using the 36-Item Short Form Health Survey. Scores were also converted to a physical health component summary (PCS), a mental health component summary (MCS) and a role/social component summary (RCS). Results In the EARNEST-PVI trial, the PVI alone strategy was associated with higher recurrence rate compared with the PVI plus additional ablation strategy. After excluding 68 patients for whom preoperative or postoperative QoL assessment was not available, 222 patients were evaluated respectively. Overall, significant improvements in PCS (46.2±11.4 to 48.7±11.4]), MCS (50.1±8.8 to 54.3±8.6) and RCS (44.6±13.3 to 48.6±11.3) occurred 12 months after ablation (P Conclusions Ablation for persistent atrial fibrillation improved both physical and mental quality of life. The PVI-plus strategy showed greater improvement in physical QoL. Funding Acknowledgement Type of funding sources: None. QoL improvement

Background/Introduction The inspIRE clinical trial was designed to assess the safety and efficacy of a fully integrated biphasic pulsed field ablation (PFA) system comprised of a multi-channel generator, variable decapolar irrigated loop circular catheter, and mapping system (Figure A) for the treatment of paroxysmal atrial fibrillation (PAF). Purpose Using this novel PFA system in a multicentre clinical trial, we present the initial feasibility of electrical pulmonary vein isolation (PVI), procedural performance, and acute safety results. Methods inspIRE is a prospective, non-randomized, multi-centre study, planned to enrol up to 550 patients. PVI is performed with the novel, variable loop circular catheter, compatible mapping system and generator. Acute procedural effectiveness (entrance block in all clinically targeted PVs post adenosine/isoproterenol challenge) and the incidence of primary adverse events (PAEs) were assessed. PAEs are defined as the occurrence of cardiac tamponade/perforation, myocardial infarction, stroke/cerebrovascular accident, thromboembolism, transient ischemic attack, permanent phrenic nerve paralysis, pulmonary edema, pericarditis, and any major vascular access complications within 7 days of the ablation procedure. Additionally, any incidence of procedure or device related death, atrio-esophageal fistula, or PV stenosis (related to the ablation procedure or study catheter) within the 12M follow-up period is classified as a PAE. Results A total of 35 PAF subjects (age 59.7±10.7 years, 54.3% male) were treated across 5 European sites by 6 operators. Acute procedural success was achieved in 100% of study subjects (Figure B) with zero incidence of PAEs. Mean total procedure time was 82.9±19.9 minutes with 27.0±11.9 minutes of PFA from first to last application. Average fluoroscopy use was 10.6±6.8 minutes and LA dwell time was 45.6±15.3 minutes. Conclusion Initial results of the inspIRE trial demonstrate the acute safety and effectiveness of the new integrated IRE circular catheter, mapping system and generator for PVI in PAF patients. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): inspIRE is a company-sponsored study funded by Biosense Webster, Inc. Figure 1. (A) PFA System; (B) PVI Voltage Map

Introduction The complication rate following pulmonary vein isolation (PVI) for atrial fibrillation (AF) has improved in recent decades with the increasing number of PVI worldwide. The effectiveness and safety of same-day discharge for PVI has not been elucidated well using a large nationwide database. Purpose The aim of our study was to evaluate the readmission rates within 30-days among patients receiving PVI for AF with the same-day discharge compared with the usual overnight observation protocol. Methods We performed a retrospective cohort study using the US Nationwide Readmission Database. Patients were divided into the two groups: the same-day discharge group and the overnight observation group (those who stayed at least one night following PVI). The primary outcome was an all-cause 30-day readmission rate following discharge in patients receiving PVI and a secondary outcome of total healthcare cost. A 1:3 propensity score matching was used to compare the safety within both protocols. Patients with peri-procedural complications such as pericardial, vascular, bleeding requiring transfusion, were excluded from the analysis. Result Among 30,776 patients (mean 67.2±11.4 years, 18,004 male (58.5%)) who received PVI from 2016 through 2018, 440 (1.42%) patients were discharged the same-day following PVI (same-day discharge group), and the remaining 30,336 patients stayed at least one night in the hospital (the overnight observation group). A propensity score analysis generated 1,751 matched pairs (440 in the same-day discharge group; 1311 in the observation overnight group). The 30-day readmission following discharge was not significantly higher in the same-day discharge group, compared to the overnight observation group (same-day discharge vs. overnight observation group: 12.7% vs. 9.7%, p=0.23; odds ratio [OR]:1.39, 95%confidence interval [CI]: 0.87–2.22) (Figure). Healthcare cost was significantly higher in the overnight observational group. ($25,237±14,036 vs. $30,749±16,383; p Conclusion In this large nationwide study using a propensity score matching analysis, there was no significant difference in 30-day readmission rates following the same-day discharge in patients receiving PVI for AF compared with the overnight observation protocol. Funding Acknowledgement Type of funding sources: None.

Background Left atrial posterior wall (LAPW) isolation is an adjunct to pulmonary vein isolation (PVI) for persistent atrial fibrillation (AF). Objective To compare the effect of LAPW box isolation with LAPW point-by-point ablation and PVI in persistent AF on 12-month arrhythmia-free survival and procedure complications. Methods 77 consecutive patients who underwent LAPW box isolation, 24 patients who underwent LAPW point-by-point ablation and 101 patients who underwent PVI for persistent AF were compared. All patients had undergone no prior ablation for AF and were followed up for one year. Results Mean time to atrial tachyarrhythmia recurrence was similar with LAPW box isolation (9.8 months, 95% CI = 9-10.7) and LAPW point-by-point ablation (10 months, 95% CI = 8.6-11.3), both were longer than PVI (8.2 months, 95% CI = 7.4-9.1, log-rank p = 0.003). There was no difference in peri-procedural complications (LAPW box isolation: 5/77, LAPW point-by-point ablation: 1/24, PVI: 6/101, p = 0.91). At 12 months, no difference in atrial tachyarrhythmia recurrence was observed between box isolation (23/77, 30%) and point-bypoint ablation (11/24, 46%, p = 0.15), but significantly higher recurrence occurred with PVI alone (58/101, 57%, p Conclusion In persistent AF, there was no difference between LAPW box isolation and point-by-point ablation in terms of mean arrhythmia-free survival, 12-month recurrence or procedure complications. Arrhythmia-free survival with either technique was longer than PVI alone, with no increase in complications.

Atrial fibrillation (AF) is associated with systemic thrombo-embolism and stroke events, which do not appear significantly reduced following successful pulmonary vein (PV) ablation. Prior studies supported that thrombus formation is associated with left atrial (LA) flow alterations, particularly flow stasis. Recently, time-resolved three-dimensional phase-contrast (4D-flow) showed the ability to quantify LA stasis. This study aims to demonstrate that LA stasis, derived from 4D-flow, is a useful biomarker of LA recovery in patients with AF. Our hypothesis is that LA recovery will be associated with a reduction in LA stasis. We recruited 148 subjects with paroxysmal AF (40 following 3–4 months PV ablation and 108 pre-PV ablation) and 24 controls (CTL). All subjects underwent a cardiac magnetic resonance imaging (MRI) exam, inclusive of 4D-flow. LA was isolated within the 4D-flow dataset to constrain stasis maps. Control mean LA stasis was lower than in the pre-ablation cohort (30 ± 12% vs. 47 ± 18%, p &lt, 0.001). In addition, mean LA stasis was reduced in the post-ablation cohort compared with pre-ablation (36 ± 15% vs. 47 ± 18%, p = 0.002). This study demonstrated that 4D flow-derived LA stasis mapping is clinically relevant and revealed stasis changes in the LA body pre- and post-pulmonary vein ablation.

Funding Acknowledgements Type of funding sources: None. Background Many tools and techniques are utilized to assess pulmonary vein isolation (PVI), such as evaluation of entrance and exit block, voltage mapping, and use of drugs such as adenosine. It is unclear which tools and techniques may provide greater sensitivity in the identification and elimination of pulmonary vein (PV) gaps, leading to better long-term outcomes. The HD Grid simultaneously records orthogonal bipolar EGMs to reduce directional sensitivity. Previously published data suggest that the use of HD Grid may improve sensitivity for gap identification. Purpose To determine, in a large cohort of procedures, the rate of gap detection when using HD Grid to check for PVI as compared to circular mapping catheters (CMC). Methods Anonymized, acute procedural data was prospectively collected in de novo AF ablation procedures in which either a 10- or 20-pole CMC or HD Grid catheter was used to assess PVI. Procedural data including gap detection and PVI assessment method were analyzed using chi-squared test. Results 559 cases from over 60 institutions in 8 countries were analyzed. Of the 559 cases, 47.4% (265/599) used HD Grid, and 52.6% (294/599) used a CMC. PV gaps were found in 52.5% (139/265) of HD Grid procedures and in 36.7% (108/294) of CMC procedures (p < 0.001). The most common PVI assessment method in both HD Grid and CMC groups was entrance/exit block (90.9%, 92.5%, respectively). Mapping as a post-ablation assessment method was used in 69.1% (183/265) of HD Grid procedures whereas it was only used in 42.8% (126/294) of CMC procedures (p < 0.001). Of the 183 HD Grid procedures that utilized mapping for PV assessment, 57.9% (106/183) used both voltage and activation mapping, 41.0% (75/183) used voltage only and 1.1% (2/183) used activation mapping only. Significantly more gaps were found in the HD Grid group that used both activation and voltage mapping (83.0%, 88/106) as compared to voltage mapping only (49.3%, 37/75, p < 0.001). At the end of the procedure, 95.8% of patients in the HD Grid group were in sinus rhythm, as compared to 84.7% of the CMC group. Conclusions While this analysis does not represent a direct comparison of the sensitivity of the two different technologies, HD Grid detected significantly more PV gaps compared to CMC in AF procedures. Previous publications have attributed similar findings to HD Grid’s ability to reduce voltage amplitude dependence on wavefront directionality. The significantly larger number of HD Grid cases that utilized mapping as a method of determining PVI could be explained by the need to maneuver the HD Grid around the circumference of the vein, which may naturally lead to map collection. This data also suggests that using both voltage and activation mapping identifies significantly more gaps as compared to only voltage mapping, however, further analysis could be warranted to better understand how these maps were collected and what map settings were used.

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): US National Institutes of Health Background Mechanisms associated with successful termination of persistent atrial fibrillation (AF) are still under debate. We sought to study the association between spatial extent of atrium with organized conduction and AF ablation success. We hypothesized that patients with large areas of atrium having 1:1 electrogram activation akin to ‘atrial tachycardia’ may have a higher likelihood of AF termination by ablation. Methods In n = 40 AF patients, n = 20 had termination by ablation ("Term"), and the remaining did not have AF termination by ablation ("Non-term"). Basket catheters (64 poles) were used to record unipolar electrograms (EGMs) in one or both atrium. Ablation targeted localized rotational/focal regions, after which pulmonary vein isolation was performed. Unipolar EGMs of 4sec duration at each 2x2 electrode neighborhood within 8x8 catheter grid were processed using a statistical correlation technique to identify the duration of 1:1 activations. Any EGM activation cycle that had a correlation above 80% was considered to be 1:1. Duration of contiguous 1:1 cycles was determined as percentage of total duration (4 sec). Results Spatial area of atrium (percentage of mapping field) and the corresponding 1:1 durations were assessed for patients in Term and Non-term groups. Fig A shows spatial 1:1 maps of a Term and a Non-term patient. Fig B shows examples of 1:1 and non-1:1 EGMs. Patients in Term group had higher average 1:1 atrial area than non-term group for any 1:1 duration (Fig C, 15 ± 22% vs 2 ± 4% with ≥70% 1:1 duration, p = 0.03). Positive and negative predictive values of duration≥70% for AF termination were 64.7%, and 75%, with specificity 60% and sensitivity 78.6%, exceeding clinical risk scores. Conclusion Persistent AF atrium shows areas of organized 1:1 conduction. Larger 1:1 atrial areas were identified in patients in whom AF terminated by ablation. Future studies should investigate mechanistic bases of organized conduction in AF. Abstract Figure.

Funding Acknowledgements Type of funding sources: None. Background The arctic front cryoballon (AF-CB) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome data. The POLARx cryoballoon incorporates unique features which may translate into improved efficacy and safety. Purpose To assess efficacy and safety of the novel POLARx cryoballoon in comparison to the fourth generation arctic front cryoballon (AF-CB4). Methods Twenty-five consecutive patients with paroxysmal or persistent atrial fibrillation (AF) were prospectively enrolled, underwent POLARx based PVI (POLARx group) and were compared to 25 consecutive patients treated with the fourth generation AF-CB (AF-CB4 group). Results A total of 100 (POLARx) and 97 (AF-CB4) pulmonary veins (PV) were identified and all PVs were successfully isolated utilizing the POLARx and AF-CB4, respectively. A significant difference regarding the mean minimal cryoballoon temperatures reached using the AF-CB4 and POLARx (-50 ± 6°C vs. -57 ± 7°C, p = 0.004) was observed. Real-time PVI was visualized in 81% of POLARx patients and 42% of AF-CB4 patients (p Conclusions The novel POLARx showed similar safety and efficacy compared to the AF-CB4. A higher rate of real-time electrical PV recordings and significantly lower balloon temperatures were observed using the POLARx as compared to AF-CB4.

Funding Acknowledgements Type of funding sources: None. Background Although pulmonary vein isolation (PVI) is an effective treatment strategy for patients with paroxysmal atrial fibrillation (AF), it is associated with limited success rates in patients with persistent AF (PersAF). In this context the left atrial appendage (LAA) was recently identified as a target of catheter ablation especially in PVI non-responders. Although effective, this strategy may cause electromechanical dissociation and was therefore assumed to be associated with an increased risk of thromboembolism despite oral anticoagulation (OAC). Since RF based LAAI showed increased rates of thromboembolism and stable LAAI is difficult to achieve in some cases, Cryoballoon-based LAAI might offer a valuable option to achieve safe and durable LAAI. Recently the fourth generation cryoballoon was introduced. Additionally, the 40% shorter tip potentially increases the safety profile as well as efficacy of CB-based LAAI. Objective To assess safety and efficacy on CB2 vs CB4 based LAAI. Methods Cryoballoon based PVI and LAAI was performed in 20 patients with PersAF and long-standing PersAF. The first 10 consecutive patients were treated by the second-generation cryoballoon (CB2) the last 10 patients were treated by the CB4. LAAI was performed by utilizing a bonus freeze protocol (freezing time 300 seconds + another 300 seconds after LAAI). Results Stable LAAI was achieved after a mean of 2.6+/- 1.7 cryoballoon applications with a mean minimal temperature of -52+/-6 °C. Unless one phrenic nerve palsy (5.6%) of the left phrenic nerve no further periprocedural complications occurred. Successful LAAI was performed in 19/20 (95%). TEE after 6 weeks detected LAA thrombus in 3/10 (30%) patients (CB2 group) and 3/10 patients (30%) (CB4 group), p = 0.99. Successful LAA-closure was performed in 16/20 patients (80%) after a mean of 75+/-59 days. The LAA was durable isolated in 8/9 patients (89%, CB2) and 6/8 patients (75%, CB4), p = 0.56). AF recurrence after 6 weeks was 1/10 (10%, CB2) and 3/9 (33%, CB4), p = 0.26. Conclusions Here we used – to our knowledge – for the first time a CB4 for LAAI, followed by a combined check for LAAI and LAA-closure after 6 weeks, compared to the CB2. LAAI was successfully isolated by both cryo-balloons in the majority of patients. Hence the use of newest cryo-balloon generation for LAAI seems a safe and successful procedure compared to earlier balloon generations. However, a relatively high rate of LAA-Thrombus was detected after LAAI. Therefore, LAA closure is mandatory in this population.

Funding Acknowledgements Type of funding sources: None. Background A novel irrigated RF balloon (RFB) for pulmonary vein isolation (PVI) was recently released in selected centers . It is a 28 mm open irrigated balloon with 10 unipolar electrodes on its surface to deploy a circular ostial lesion set around the PVs. An inner lumen spiral catheter allows for real time PVI visualization during the ablation. Methods Data from consecutive RFB procedures were collected and analysed. After a single transseptal puncture and selective PV angiograms a 3D map of the left atrium was acquired. Sequential PVI was performed using the RFB: each application lasted 60 seconds, the posterior electrodes were identified to stop the energy delivery after 20 seconds. Real time to isolation data were acquired. A 3D bipolar remap was finally performed to observe the level of isolation. A temperature probe was used to monitor the local esophageal temperature (LET) with a cut off of 39°C. Acute procedural data and complication were collected. Endoscopy was scheduled the day after procedure. Results Data from 10 consecutive RFB procedures were analyzed: 6/10 patients were male, 67 ± 9 years old, 8/10 with history of paroxysmal AF. A total of 36 PVs were targeted and isolated with the RFB, with a mean of 7,3 ± 4,0 applications per patient and 2,0 ± 1,2 applications per PV. First pass "single shot" isolation was achieved in 22/36 (61%), time to isolation during the first application was observed in 29/36 (80%) PVs, but an acute reconnection was observed in 10/29 (35%) isolated PVs. Mean time to sustained isolation was 13 ± 5 sec., mean time to non-sustained isolation was significantly longer (29 ± 17 sec; p = 0,001). Procedure time was 57 ± 16 min., left atrial dwell time 50 ± 14 min, ablation phase time 29 ± 14 min and fluoroscopy time was 10 ± 4 minutes. An esophageal temperature above 39°C was recorded in 2/36 PVs. No phrenic nerve palsy was recorded. 7/10 patients underwent endoscopy and no thermal lesions were detected. No other complications were recorded. Conclusion The novel irrigated RFB seems to allow an effective, safe and fast pulmonary vein isolation. More studies are needed to optimize energy dosing to possibly increase the rate of durable single shot PVI.

Funding Acknowledgements Type of funding sources: None. Background The safety of Ablation Index (AI)-guided 50W ablation of atrial fibrillation (AF) remains uncertain, and the effects of this high power on other ablation parameters have not been described. We aimed to compare the safety profile of AF ablation using 50W and 35-40W. Methods 59 patients undergoing AI-guided Pulmonary Vein Isolation were enrolled including 31 with 50W and 28 with 35-40W. A contact force (CF)-sensing ablation catheter (Thermocool SmartTouch) was used to deliver point-by-point ablation according to the CLOSE protocol targeting AI values of 550-600 on the left atrial (LA) anterior wall and 400-450 on the LA posterior wall. The generator impedance graph was monitored in real-time for each lesion application. All VisiTags (n = 3766) across both groups were analysed retrospectively. Excessive ablation was defined as AI >600 on the anterior wall and >500 on the posterior wall. Results The mean AI was significantly higher in patients receiving 50W ablation (512 [±61] vs. 500 [±63] with 35-40W ablation, p Scatterplots showing the relationships between contact force (CF) and ablation time for the anterior and posterior segments of the LA for both groups are shown in the Figure. For the anterior wall, the slope of the regression line for the 50W group was -1.0 and for the 35/40W group was -0.5. Overall, there was moderate correlation between the variables CF and time in both groups (50W group: r -0.490, p In the 50W group, high CF was an important predictor of excessive AI. The AUCs for anterior and posterior wall 50W ablations were 0.844 (95% CI, 0.774-0.914; p Conclusion Use of 50W ablation appears to be safe. but may lead to AI overshoot. Our study suggests that operators should strive to limit CF to 15g on the anterior wall and 10g on the posterior wall. Abstract Figure. Relationship between CF and abl time

Funding Acknowledgements Type of funding sources: None. Background/Introduction: A significant number of patients experience recurrent atrial fibrillation (AF) after ablation. Predicting who will or will not benefit from AF ablation is challenging. Although various risk scores have been designed to predict outcomes after AF ablation, comparative data are sparse and external risk score validation is often lacking. Purpose In this study, we aimed to compare ten previously described risk scores with regard to their predictive value for post-ablation AF recurrence and procedural complications. Methods A total of 482 AF patients (37% non-paroxysmal AF, 66% male, mean age 62 ± 9 years) undergoing initial radiofrequency pulmonary vein isolation (RF-PVI) were included in the present analysis. Prior to ablation, all patients underwent both transthoracic echocardiography and either cardiac computed tomography imaging or cardiac magnetic resonance imaging. The following risk scores were calculated for each patient: APPLE, ATLAS, BASE-AF2, CAAP-AF, CHADS2, CHA2DS2-VASc, DR-FLASH, HATCH, LAGO and MB-LATER. The predictive performance of the risk scores for AF recurrence and complications were assessed separately by receiver operating characteristic (ROC) curves. Results Median follow-up was 16 (12-31) months. AF recurrence after the 90-day blanking period was observed in 199 patients (41%), occurring after a median of 183 (124-360) days after ablation. Overall procedural adverse event rate was 6%. The HATCH score was the only score without predictive value for recurrent AF after ablation (area under curve [AUC] 0.545). All other investigated scores demonstrated statistically significant but poor predictive value for recurrent AF after ablation (AUC 0.553-0.669). CHA2DS2-VASc and CAAP-AF were the only risk scores with predictive value for procedural complications (AUC 0.616, p = 0.043; AUC 0.615, p = 0.044; respectively). ROC curve analyses of the studied risk scores for the prediction of AF recurrence and complications are shown in Figure. Conclusion Currently available risk scores perform poorly in predicting outcomes after RF-PVI. These data suggest that the utility of these scores for clinical decision-making is limited. Abstract Figure. ROC curve analyses of risk scores

Funding Acknowledgements Type of funding sources: None. OnBehalf REGIONAL Background Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) has become an established procedure for the treatment of symptomatic paroxysmal and persistent atrial fibrillation (AF). The safety and efficacy of PVI at community hospitals with low to moderate case numbers is unknown. Aim To determine safety and efficacy of PVI using CBA performed at community hospitals with limited annual case numbers. Methods 1004 PVI performed consecutively between 01/2019 and 09/2020 at 20 community hospitals (each Results Mean number of PVI using CBA/year was 59 ± 26. Mean procedure time was 90.1 ± 31.6 min and mean fluoroscopy time was 19.2 ± 11.4 min. Isolation of all pulmonary veins could be achieved in 97.9% of patients, early termination of CBA due to phrenic nerve palsy was the most frequent reason for incomplete isolation. There was no in-hospital death. 2 patients (0.2%) suffered a clinical stroke. Pericardial effusion occurred in 6 patients (0.6%), 2 of them (0.2%) required pericardial drainage. Vascular complications occurred in 24 patients (2.4%), in 2 of these patients (0.2%) vascular surgery was required. In 48 patients (4.8 %) phrenic nerve palsy was noticed which persisted up to hospital discharge in 6 patients (0.6%). Conclusions PVI for paroxysmal or persistent AF using CBA can be performed at community hospitals with high efficacy and low complication rates despite low to moderate annual procedure numbers.

Funding Acknowledgements Type of funding sources: None. Background Diabetes mellitus (DM) has been identified to play an important role in the regulation of atrial fibrillation (AF). Data concerning the impact of DM on the development of individual arrhythmia substrates are still lacking. Purpose Therefore, the primary aim of this study was to examine the outcome of cryoballoon-guided pulmonary vein isolation (PVI) in patients (pts) suffering from DM and coexisting AF. Methods 523 consecutive pts undergoing initial PVI using the 2nd generation cryoballoon were analysed. 273 pts (52%) suffered from paroxysmal AF (PAF) (51 ± 23.2 years old, 26% female), 250 pts (48%) from persistent AF (PERS) (63.9 ± 10.0 years old, 30% female) and 69 pts (13%) were diagnosed with DM (68 ± 19.6 years old, 30% female). Follow-up (FU) visits were performed at 3, 6 and 12 months including 7-day Holter ECGs. Primary endpoint was the first documented recurrence of any atrial arrhythmia after a 3 months blanking period (> 30 sec.). Results Within the observation period of 12 months AF recurrence occurred in 29% (n = 151 pts). Regardless of the coincidence of DM, PAF pts were significantly younger than those with PERS (p = 0.001). PAF pts additionally suffering from DM presented with a significantly higher risk for arrhythmia recurrence (p = 0.047). Multivariate analyses verified DM as a strong independent predictor for arrhythmia recurrence associated with a > 4 fold higher risk for recurrence after ablation (p = 0.009, hazard ratio (HR) 4.363, confidence interval (CI) 1.46-13.07). PERS pts showed a slightly increased rate of arrhythmia recurrence when additional DM was diagnosed. In these patients multivariate analyses revealed that DM was associated with a 43% higher risk for arrhythmia recurrence (p = 0.321, HR 1.143, CI 0.59-2.22). Beyond that, severe gender disparities were observed with female gender as independent predictor for arrhythmia recurrence (p = 0.027*, HR 1.927, CI 1.079-3.440). Conclusions DM has relevant implication for arrhythmia recurrence after PVI. More distinct effects were observed in PAF patients following AF ablation. This could be related to more severe arrhythmia substrates in PAF pts suffering from DM compared to PAF pts without additional DM and even more substantial structural changes in PERS. Thus, individual paths in ablation management are required in these pts with AF and coexisting DM.

Funding Acknowledgements Type of funding sources: None. Background Over the last 20 years various techniques have been developed striving for safer and more durable pulmonary vein isolation (PVI). The three most commonly used tools are pulmonary vein ablation catheter (PVAC) and cryoballoon (‘single-shot’ techniques), and point-by-point (PBP) radiofrequency ablation using 3D electroanatomical mapping (EAM). Objective Evaluate the safety and efficacy of the different techniques in an unselected population undergoing de-novo ablation for persistent or paroxysmal atrial fibrillation (AF) at a single high-throughput centre. Method Retrospective, single-centre study of consecutive AF ablations between March 2017 and April 2018. Demographic, procedural and outcome data were analysed. Results Over the study period 329 first-time PVI procedures were performed. 37.4% were performed using PBP, 39.8% using cryoballoon and 22.8% using PVAC. There was no significant difference in age or sex between different ablation technique groups. 238 procedures were performed for paroxysmal AF and 91 for persistent AF. A higher proportion of the persistent cases were performed using point-by-point techniques compared to paroxysmal cases (58.2% vs 29.0%, p < 0.05). Procedural times were significantly longer in the group undergoing PBP ablation compared to cryoballoon or PVAC. However, there was no statistically significant difference in 12-month freedom from symptomatic AF or procedural complications between the groups. Conclusions PBP, PVAC and cryoballoon AF ablation all appeared equally efficacious in an unselected population, though PVAC and cryoballoon procedures were shorter. All procedures were associated with a low adverse event rate. Prospective examination is required to substantiate this finding. Table 1CARTOn= 123Cryoballoonn= 131PVACn = 75p-valueAge/years61.7 ± 9.259.5 ± 10.661.7 ± 9.70.14Male92 (74.8)88 (67.2)49 (61.3)0.80Paroxysmal AF70 (56.9)106 (78.6)62 (82.7)0.14Cardiovascular risk factors Hypertension Diabetes Ischaemic heart disease Cerebrovascular disease Heart failure Dyslipidaemia73 (59.3)23 (18.7)40 (32.5)2 (1.6)0 (0) 12 (9.8)79 (60.3)19 (14.5)45 (34.4)0 (0)1 (0.8)16 (12.2)43 (57.3)16 (21.3)22 (29.3)1 (1.3)0 (0)10 (13.3) 0.58 0.24 0.62 - - 0.71Left atrial diameter/cm4.2 ± 0.74.1 ± 0.73.9 ± 1.00.69Procedure time/mins191.3 ± 39126.7 ± 24117.4 ± 30

Funding Acknowledgements Type of funding sources: None. Introduction Ablation Index (AI) software has been associated with better freedom from atrial arrhythmias after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF). There is conflicting data regarding the relationship between high sensitivity cardiac Troponin I (Hs-cTnI) and arrhythmia recurrence. The objective was to evaluate the impact of AI on Hs-cTnI level and on ablation effectiveness quotient (AEQ) and to assess if these markers are predictors of arrhythmia recurrence. Methods Prospective observational study of consecutive patients referred for PVI for paroxysmal AF ablation from October 2017 to June 2018 according to a pre-specified AI protocol. Procedural endpoints and 2-year follow-up outcomes were assessed and compared to a retrospective cohort of conventional PVI contact-force-guided group . Results A total of 56 patients were included: 29 patients the AI group and 27 patients in the control group. The mean age was 60.5 ± 10.3 years, 48% males. Left ventricular ejection fraction (60 ± 6 % AI vs 61 ± 5 % control, P = 0.07) and left atrium diameter (43 ± 7 mm AI vs 44 ± 6 mm control, P = 0.58) were comparable between groups. First-pass isolation was shown to be higher in the AI group (79% AI vs 44%, p= 0.01). Mean number of radiofrequency applications was lower in the AI group (93 ± 24 vs 111 ± 30, P = 0.02). Average contact-force was similar between groups (17.6 ± 4.1 g vs 22.6 ± 10.7 g, P =0.166). Patients that performed PVI guided by the AI had lower Hs-cTnI (1815 ± 1146 ng/L vs 3274 ± 1696 ng/L, p Conclusions These data suggest that AI-guided catheter ablation is associated with reduced levels of of Hs-cTnI and AEQ. Neither Hs-cTnI and AEQ should be used to predict arrhythmia recurrence. Abstract Figure.