Typical Flutter Research Articles

Atrial Topology for a Unified Understanding of Typical and Atypical Flutter.

Macroreentry stands as the predominant mechanism of typical and atypical flutter. Despite advances in mapping, many aspects of macroreentrant atrial tachycardia remain unsolved. In this translational study, we applied principles of topology to understand the activation patterns, entrainment characteristics, and ablation responses in a large clinical macroreentrant atrial tachycardia database. Because the atrium can be topologically seen as a closed sphere with holes, we used a computational fixed spherical mesh model with a finite number of holes to induce and analyze macroreentrant atrial tachycardia. The ensuing insights were used to interpret high-density activation maps, postpacing interval-tachycardia cycle length values (difference between postpacing interval and tachycardia cycle length), and ablation response in 131 cases of typical and atypical flutter (n=106 left atrium, n=25 right atrium). Modeling of macroreentrant atrial tachycardia revealed that reentry on closed surfaces consistently manifests itself as paired rotation and that an odd number of critical boundaries is mathematically impossible. Together with mathematical confirmation by the index theorem, this led to a unifying construct that could explain the number of loops, difference between postpacing interval and tachycardia cycle length values, and ablation outcomes (termination, no change, or prolongation in tachycardia cycle length) in all 131 cases. Combining topology with the index theorem offers a novel and cohesive framework for understanding and managing typical and atypical flutter.

Left atrial substrate modification for persistent atrial fibrillation and left atrial macro or microreentrant tachycardia using a single-shot pulsed field ablation system - a single centre case series

Abstract Background Pulsed field ablation (PFA) is a novel ablation technique for pulmonary vein isolation (PVI) in patients with paroxysmal and persistent atrial fibrillation. However, data for efficacy and safety of PFA for left atrial substrate modification in patients with long-standing persistent atrial fibrillation (AF) and macro- as well as microreentrant atrial tachycardia (AT) is scarce. Aim Here we provide a retrospective, single-centre case series regarding efficacy and safety of left atrial substrate modification, using a single-shot PFA system. Methods and Results Over a period of 6 months, 8 patients with long-standing persistent AF and AT underwent Re-PVI with left atrial substrate modification using a single-shot PFA system. Median age was 63 years (IQR 58 - 75), and 4/8 of patients were female. Time from first diagnosis of AF was 7 years (IQR 4 –10). All but 1 patient underwent previous PVI (IQR 1-3) with (5/7) or without (2/7) prior substrate modification using radiofrequency ablation. On transthoracic echocardiography, all patients showed severe left- and right-atrial enlargement, with LA volume of 58 ml/m2 (IQR 49.7–72) and RA diameter of 62 mm (IQR 55-75). In 8 patients, 9 ATs and 2 typical flutters were treated with PFA. Following PVI, additional posterior wall isolation was performed in 6/8 patients, roof in 6/8, and anterior wall (between superior mitral anulus and RSPV) in 4/8 patients. In addition, 2/8 patients had cavotricuspid isthmus ablation for typical atrial flutter. All patients received atropine prior to PVI, as well as bolus of nitro-glycerine prior to PFA of anterior wall and/or cavotricuspid isthmus. Acute success rate was 100% and all ATs as well as typical flutter terminated with PFA. After median follow-up time of 88 days (IQR 61-112), 3 patients had a documented recurrence of AF/AT, in 2 of which electrical cardioversion was necessary. We observed no acute and/or chronic complications following PFA, i.e. no pericardial effusion/tamponade, TIA/stroke, myocardial infarction, coronary artery spasm, AV-block, bleeding, or atrioesophageal fistula. Conclusion In this small, single-centre case series, left atrial substrate modification for long-standing persistent AF and AT using a single-shot PFA system was safe and showed an excellent acute success rate.

Organization of atrial flutter during pulse field ablation for atrial fibrillation

Abstract Background Pulse Field Ablation (PFA) has been acknowledged as an effective and safe tool for ablation of Atrial Fibrillation (AF). It is known that during AF ablation, the arrhythmia may organize into atrial flutter. The left atrial posterior wall is identified as a critical source of non-Pulmonary Vein (PV) triggers that facilitate maintenance of atrial fibrillation. Objective The purpose of this study is to investigate the phenomenon of atrial flutter organization from AF during the application of PFA. Methods This prospective multicentric study encompasses 117 consecutive patients with persistent AF across American and European institutions, undergoing first time catheter ablation. All receive isolation of the Pulmonary Veins (PV) plus Posterior Wall (PW) isolation. The PW isolation procedure targeted the standard area between the PVs and extended to the area demarcated by the line connecting the inferior borders of the inferior PV-encircling lesions to the coronary sinus defined lower part of PW (Fig. 1). The study documented the specific locations where AF organized into atrial flutter with a stable cycle length during PFA. Results Organization of AF to atrial flutter during PFA was observed in 72 (61.5%) patients. Analysis of the organization of flutter revealed that in 41 (56.9%) of these cases, flutter began while ablating the lower part of the PW. Moreover, 9 (12.5%) initiated at one of the PVs, and 22 (30.5%) during the ablation of the posterior wall. Notably, the flutter was described as perimitral flutter in 33 (45.8%), as typical flutter in 24 (33.3%), and as roof-dependent flutter in 15 (20.8%) of cases. Conclusion The findings underscore that during PFA for AF, there is a pronounced tendency for the arrhythmia to organize into atrial flutter, particularly during the ablation of the lower posterior wall. Notably ablation in the left atrium organized AF in typical atrial flutter at a considerable rate.Ablation on lower part of PW

Findings at repeat ablation after complex left atrial pulsed field ablation for longstanding persistent atrial fibrillation

Abstract Background There is a limited knowledge on atrial arrhythmias recurring after complex left atrial (LA) pulsed field ablation (PFA) for longstanding persistent atrial fibrillation (LSPAF). Purpose To present recurrent atrial arrhythmias and their sources found at repeat ablation following PFA for LSPAF. Methods and results Of 214 patients with LSPAF (age 65±8, 53 females, continuous AF for 30±27 months) with complex LA PFA (Farapulse) in 10/2021-10/2023, 19 patients (64±8 years, 5 females) underwent repeat ablation for recurrent AF or arial tachycardia (AT) in 20 procedures. First PFA procedure included pulmonary vein isolation (PVI), roof/posterior wall, and mitral isthmus/coronary sinus/Ligament of Marshal region (LOM) ablation. At repeat ablation, 3D activation and entrainment mapping and ablation identified the AF/AT sources; ATs sources were classified as macroreentry (MRAT) (perimitral, roof-dependent, typical flutter) or localized (LOCAT) in case of smaller reentry or ectopic origin. Results The clinical recurrent arrhythmias included paroxysmal AF (n=1), persistent AF (n=2), paroxysmal AT (n=1) or persistent AT (n=16). At the onset of repeat ablation, persistent AF/AT was present (n=15) or had to be induced (n=5). AF was finally present during the procedure in 8 patients, and was terminated by ablation directly into SR (n=3) or into intermediate AT (n=3) (conversion sites included LA ridge/LOM region 2x, RA septum 1x, RA low lateral 2x, CTI 1x), or required DCC (n=2). Primary recurrent or from AF converted AT was present in 15 patients; only MRAT in 6 patients, only LOCAT in 3 patients, and both AT types in 6 (patients). Of MRAT (N. ATs = 16), there were 12 perimitral ATs, 0 roof-dependent AT, and 2 typical flutters. Of LOCATs, sources were located at LA anterior wall 4x, LA septum 2x, LA roof 1x, LA ridge/LOM 1x, persistent left vena cava 1x, and RA – para SA node 1x. Recurrent AF/AT sources were targeted by radiofrequency or PFA in 16 and 4 cases, respectively, all spontaneous and induced AF/AT were finally terminated into SR in 16 cases, subsequent noninducibility by atrial pacing up to 300 bpn was achieved in 13 cases, and recurrent AF/AT occurred in 3 patients. Conclusion At repeat ablation PFA (Farapulse) for LSPAF, recurrent AT dominated over AF, MRAT slightly prevailed over LOCAT, mostly constituted by perimitral AT, while roof-dependent AT recurrence was reduced to zero. A majority of AF/AT sources were located outside prior PFA lesions at the LA anterior wall, septum and the right atrium.

Pulsed field ablation for complex resistant atrial tachycardia recurring after radiofrequency ablation of persistent atrial fibrillation

Abstract Background There is a limited knowledge on immediate and long-term efficacy of pulsed field ablation (PFA) for residual atrial tachycardia (AT) recurring after persistent atrial fibrillation ablation (AF). Purpose To present immediate and medium-term outcome of PFA (Farapulse) for complex AT recurring after ≥1 radiofrequency ablation (RFA) of primary (longstanding) persistent AF. Methods In 5/2022-10/2023, 81 patients (64±8 years, 19 females) underwent PFA for complex AT in 83 PFA procedures after prior RFA procedure(s); in first (n=21), second (n=33), third (n=23), fourth (n=5), or fifth (n=1) repeat ablation procedure, respectively. Mapping/ablation strategy was directed by the CS activation/entrainment to: 1) no 3D mapping and direct PFA in left atrium (n=67); 2) PFA directly after 3D LA mapping (n=9); 3) PFA following RFA after 3D LA mapping (n=7). AT sources were classified as macroreentry (MRAT) (perimitral, roof-dependent, typical flutter) or localized (LOCAT) in case of smaller reentry or ectopic origin. Results At the procedure onset, persistent AT was present in 58 patients, in the remaining cases AT (n=21) or AF (n=4) were induced. AF eventually occurred at some time of procedure in another 10 patients and was terminated by ablation at LA ridge/CS/LOM region 8x, LA posterior wall 3x, LUPV 1x, RUPV 1x, and RA low lateral wall 1x. Only MRAT, only LOCAT, or both AT types were found at 34 (41%), 35 (42%), and 14 (17%) procedures, respectively. A total of 125 ATs was identified (1, 2, and 3 ATs in 52, 20, and 11 patients). MRAT (n=60) included 32 perimitral ATs, 20 roof-dependent ATs, and 8 typical flutters. LOCAT (n=65) included RUPV source (n=1), LA extraPV sources (n=59), and RA sources (n=5). SR was restored with a 5±7 PFA applications at the site of AF source, total of PFA deliveries was 71±27, and procedure and fluoroscopy times were and 89±37 and 9±5 minutes, respectively. In the 7 patients with initial ineffective 6, 6, 11, 5, 18, 10, and 2 minutes of RFA, the AT was converted into SR by subsequent 1, 4, 1, 13, 4, 24, and 20 PFA applications. All ATs were terminated and noninducibility was achieved in 82 (99%) and 74 (89%) procedures, respectively. In 52 patients with >3 month follow-up, 46 (88%) patients remain in stable SR (41 / 79%) off AAD); 3 and 3 patients have paroxysmal or persistent AT. Conclusion PFA with catheter Farapulse can affect complex/epicardial AT sources resistant to RFA in prior or present ablation procedure; however, there is a certain discrepancy between high efficacy in AT terminating and medium-term clinical outcome.

Pattern of reconnection after isolation of the pulmonary veins with a pulsed-field ablation

Abstract Background Pulsed Field Ablation (PFA) has proven is efficacy for pulmonary vein isolation (PVI) with an acute success in 99.9% of PVI and few major complications (1.6% of patients). (1) However, in redo procedures, the durability of the PVI was 63% at a median of 6 month in a study of Kueffer and al. (2) Purpose The purpose of this study is to analyze the pattern of these reconnections in the redo procedures. Methods We retrospectively analyzed the data among the patients that had a PVI with PFA in our institution between 1 October 2022 and 1 October 2023 who were referred for a recurrence of a tachyarrhythmia. Results Of 350 patients treated for PVI with PFA, 14 patients (4%) were referred for a recurrence of tachyarrhythmia. Among them, three (21%) were female and the median age was 72 years old [IQR 69-78]. The Chadvasc score was > 2 in 7 (50%) patients and the DR flash score was > 3 also in 7 (50%) patients. The patients were referred for paroxysmal AF (4/14 patients), persistent AF (5/14 patients), typical flutter (2/14 patients) or atypical flutter (3/14 patients). All patients had a high resolution 3D electro-anatomical mapping, in a median time of 7,4 months [IQR 5,1-11,8]. The median left atrium volume was 169 mL [IQR 150-180] and 66% of the pulmonary veins were isolated. Only two patients (14%) had durable PVI in all their veins. Two of the patients had a posterior box with their PVI and the box was blocked at 7 and 13 months after the PFA. The reconnections of the pulmonary veins was mainly in the anterior aspect of the right superior PV (6/19 reconnections, 32%). There were two typical shapes of reconnection, the « missing petal » and the « collar » patterns. Conclusion In a redo procedures at 7 months after a PFA, 14% of the patients had durable PVI and 66% of the veins were isolated. The reconnections were mainly in the anterior right superior PV and had often a typical « missing petal » or « collar» patterns.Percentage ReconnectionsPatterns Reconnections

Evaluation of the cavotricuspid isthmus contractile kinetics within an interventional CMR environment

Abstract Background Cavotricuspid isthmus (CTI)-dependent flutter is a common arrhythmia with recurrences following ablation up to 50%. Previous static morphological analysis have shown that CTI anatomical variability has an impact on ablation time and procedural success. However, whether the contractile kinetics of the CTI affect procedural success remains unknown to date. Purpose Assessment of the contractile kinetics of the CTI in a cardiac magnetic resonance (CMR) environment for patients (pts) referred for typical flutter ablation. Method 32 consecutive pts with typical right atrial (RA) flutter from our Heart Center were included in this study. RA wall contours during a single cardiac cycle were delineated on CMR 2D-images using the Tomtec software. CTIs were divided in 5 segments for detailed motion analysis as shown in the figure 1A. CTI length and displacement were measured both in caudo-cranial and postero-anterior directions. Quantification of the CTI kinetics was performed in Python by computing the 2D-Euclidean distance (between two extreme temporal positions of CTI points). Results The mean CTI length of the study population (mean age 66±10 years, 29 males) was 32±13 mm during RA systole and 49±15 mm during RA diastole, resulting in a mean CTI change of 17±7 mm over one cardiac cycle (maximum – minimum length). Figure 1A shows representative MRI views of the CTI during RA systole and diastole. Figure 1B shows examples of hypo- and hyperkinetics CTI from 2 representative pts. Figure 2C shows a gradual increase in segment displacement postero-anteriorly (8.1±7.3 vs 17.2±8.1 mm, p<0.05) and caudo-cranially (1.6±0.8 vs 4.5±2.4 mm) from the Eustachian valve toward the Tricuspid valve. Figure 2D indicates that the 2D-Euclidean displacement of the 5 segments varied between 8±7.7 mm and 18±8.5 mm depending on their location. Interestingly, the overall CTI displacement was 4.5 times greater forward than upward. Conclusion To our knowledge, this is the first study investigating the kinetics properties of the CTI in sinus rhythm of patients with typical RA flutter. The CTI showed displacements both in postero-anterior and caudo-cranial directions, with a gradual increase from the Eustachian to the Tricuspid valves. CTI displacement appeared highly variable across patients. Whether the kinetics of the CTI correlate with ablation success will be investigated shortly.

Incidence, types, and predictors of AF recurrence after AF ablation with pulsed field ablation. A single-centre experience

Abstract Background Pulsed field ablation (PFA) is an emerging method for the ablation of atrial fibrillation (AF). As there are few data on incidence, types, and predictors of AF recurrence after PFA for AF ablation, we are continuously analysing our cohort. Methods We report our outcome data after PVI with PFA. Each procedure was performed under deep sedation with propofol and fentanyl. Before transeptal puncture, unfractionated heparin was administered to maintain an ACT level >300sec throughout the procedure. Isolation of pulmonary veins was started after administration of 1mg of atropine with 8 applications per vein (4 in basket, 4 in flower configuration). In recent months we have routinely performed 2 additional ablations in flower configuration with an anterior twist at both right pulmonary veins. All veins were checked for entrance- and exitblock to confirm isolation in sinus rhythm. An additional ablation was performed if necessary. Results In total, 231 patients were analysed. Mean age was 62±10 years, 38% were female. Mean CHADS-VASc score was 2±1. 61% had paroxysmal AF (PAF), 36% persistent AF, and 3% patients had long-standing persistent AF. In 85% (n=197) first-pass isolation of all veins was possible. Primary PV isolation was achieved in all patients at the end of the procedure. In addition to PVI, the cavo-tricuspid isthmus (CTI) was blocked in 6% (using radiofrequency ablation in case of previously or during the procedure documented typical flutter) and the posterior wall was isolated in another 6% during the first procedure. Mean procedure time was 60±20 minutes (24-175 minutes), mean X-ray time 19±9 minutes. In 231 procedures, only two catheter-associated complications were documented. 38 patients (16%) had arrhythmia recurrence after a blanking period of 3 months and a mean follow-up of 273±177 days. Mean time to recurrence was 171±84 days. Women were more likely to have recurrences [OR 2.042 (CI 95% 1.012-4.121), p<0,05]. Patients who had undergone any type of cardiac surgery prior to ablation were also significantly more likely to have recurrence [OR 0.517 (CI 95% 0.116-0.212); p<0.001]. Patients with no other comorbidities were more likely to remain free from arrhythmias [OR 0.792 (95% CI 0.736-0.853); p<0,01]. The type of AF did not make a significant difference according to the risk of recurrence in this cohort. To date, we have performed 18 re-do procedures in patients after PVI with PFA. The recurrent arrhythmia was AF in 39% (n=7), atypical AT in 50% (roof-dependent: 28%, n=5; mitral isthmus dependent: 22%, n=4), and CTI-dependent flutter in 39% (n=7). All but one patient had PV reconnections, and all were successfully reablated. Conclusion PFA success rate is similar to that of thermal techniques. Procedure time is shorter in experienced operators and the complication rate is low in our cohort. Results from RCTs are needed to further evaluate this new method compared to other ablation techniques.

"UNUSUAL" ATRIAL FLUTTER: A CASE REPORT

Abstract A 64–years old male patient was admitted in the Emergency Department with signs of heart failure in a setting of dilated hypokinetic cardiomyopathy with severe depression of left ventricular ejection fraction and no severe coronary artery disease. In the previous medical history: systemic arterial hypertension, obesity, dysthyroidism due to amiodarone, history of atrial fibrillation treated by transcatheter ablation in the left atrium with pulmonary veins isolation (PVI) and the creation of an anterior line in 2010. The ECG documented an atrial flutter rhythm 2:1 probably typical (Fig. 1). An indication was therefore made for hospitalization in Cardiology. After the restoration of a good hemodynamic state, given the persistence of the atrial tachyarrhythmia, an indication for transcatheter ablation was formulated. The electrophysiological study highlighted an activation sequence suggestive of typical common flutter (cranial–caudal right atrial activation; proximal–distal left atrial activation). We then proceeded to ablate the cavo–tricuspid isthmus without interrupting the arrhythmia. Therefore, left and right atrial electroanatomical mapping was performed which confirmed the right isthmic block and documented the left origin of the flutter, showing conduction gaps in the ostia of the pulmonary veins and in the previous anterior ablation line between the mitral annulus and the right superior pulmonary vein (RSPV) (Fig 2,3). Ablation of these gaps effectively stopped the arrhythmia. At the end of the procedure, after stimulation via atrial bursts of up to 200 msec there was no induction of arrhythmias. One month after the procedure, there was an improvement in the contractile function of the left ventricle. Discussion: This clinical case offers us an example of how the analysis of the surface ECG alone is not sufficient to adequately describe the complexity of the arrhythmic substrate characterizing an arrhythmia such as atrial flutter or atrial fibrillation. The electrophysiological study through electroanatomical reconstruction of endocavitary activation proves indispensable for the correct identification and consequent treatment of these complex arrhythmias, with clear clinical benefits for the patient.

Multi-Passage harmonic balance method for flutter prediction in multi-row configurations

A multi-passage harmonic balance method is presented for flutter prediction in multi-row configurations, and particular focus is on simulation of more than two blade rows. The unsteady flows in such configurations contain two kinds of multiple perturbations: one refers to those who have different frequencies and the other one refers to those who have the same frequency but different inter-blade phase angles (IBPAs). Most of current harmonic balance methods only consider the former one and the applications have been restricted to two-blade-row configurations. In the few studies that consider more rows, a one-to-one correspondence assumption between frequency and IBPA is usually made putting extra limitation on the used modes. This motivates our work, and a simple but effective idea is proposed by adding passages adopted per row. The theoretical basis of this work is provided by the spinning mode analysis. The present method is developed based on the time-spectral and multi-frequential form of harmonic balance. The treatment of pitchwise and inter-row boundary conditions in the case of multi passages are particularly addressed. A recently-developed Jacobian-free Newton-Krylov method with a simplified LU-SGS preconditioner is employed to solve the resultant harmonic balance equations. For validation, two typical multi-row flutter cases are investigated. The numerical results show the validity and accuracy of the developed method.

Cavotricuspid Isthmus-Dependent Atrial Flutter. Beyond Simple Linear Ablation.

The demonstration of a peritricuspid circular movement with a zone of slow conduction in the cavotricuspid isthmus, together with the high efficacy of linear ablation and widely accepted acute endpoints, has established typical flutter as a disease with a well-defined physiopathology and treatment. However, certain aspects regarding its deeper physiopathology, ablation targets, and methods for verifying the results remain to be clarified. While current research efforts have primarily been focused on the advancement of effective ablation techniques, it is crucial to continue exploring the intricate electrophysiological, ultrastructural, and pharmacological pathways that underlie the development of atrial flutter. This ongoing investigation is essential for the development of targeted preventive strategies that can act upon the specific mechanisms responsible for the initiation and maintenance of this arrhythmia. In this work, we will discuss less ascertained aspects alongside the most widely recognized general data, as well as the most recent or less commonly used contributions regarding the electrophysiological evaluation and ablation of typical atrial flutter. Regarding electrophysiological characteristics, one of the most intriguing findings is the presence of low voltage zones in some of these patients together with the presence of a functional, unidirectional line of block between the two vena cava. It is theorized that episodes of paroxysmal atrial fibrillation can trigger this line of block, which may then allow the onset of stable atrial flutter. Without this, the patient will either remain in atrial fibrillation or return to sinus rhythm. Another of the most important pending tasks is identifying patients at risk of developing post-ablation atrial fibrillation. Discriminating between individuals who will experience a complete arrhythmia cure and those who will develop atrial fibrillation after flutter ablation, remains essential given the important prognostic and therapeutic implications. From the initial X-ray guided linear cavotricuspid ablation, several alternatives have arisen in the last decade: electrophysiological criteria-directed point applications based on entrainment mapping, applications directed by maximum voltage criteria or by wavefront speed and maximum voltage criteria (omnipolar mapping). Electro-anatomical navigation systems offer substantial support in all three strategies. Finally, the electrophysiological techniques to confirm the success of the procedure are reviewed.

Risk of atrial arrhythmias in patients with ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy

BackgroundIn arrhythmogenic right ventricular cardiomyopathy (ARVC), risk of atrial arrhythmias (AAs) persists after ventricular tachycardia (VT) ablation. ObjectiveThe purpose of this study was to determine the type, prevalence, outcome, and risk correlates of AA in ARVC in patients undergoing VT ablation. MethodsProspectively collected procedural and clinical data on ARVC patients undergoing VT ablation were analyzed. Risk score for typical atrial flutter was determined from univariate logistic regression analysis. ResultsOf 119 consecutive patients with ARVC and VT ablation, 40 (34%) had AA: atrial fibrillation (AF) in 31, typical isthmus-dependent atrial flutter (AFL) in 27, and atrial tachycardia/atypical flutter (AT) in 10. Seventeen patients (43%) with AA experienced inappropriate defibrillator therapy, with 15 patients experiencing shocks. Ablation was performed for typical AFL in 21 (53%), AT in 5 (13%), and pulmonary vein isolation for AF in 4 (10%) patients and prevented AA in 78% and all AFL during additional mean follow-up of 65 months. Risk score for typical flutter included age >40 years (1 point), ≥moderate right ventricular dysfunction (2 points), ≥moderate tricuspid regurgitation (2 points), ≥moderate right atrial dilation (2 points), and right ventricular volume >250 cc (3points), with score >4 identifying 50% prevalence of typical flutter. ConclusionAAs are common in patients with ARVC and VT, can result in inappropriate implantable cardioverter-defibrillator shocks, and typically are controlled with atrial ablation. A risk score can be used to identify patients at high risk for typical AFL who may be considered for isthmus ablation at the time of VT ablation.

Pulmonary vein isolation durability after very high-power short-duration ablation utilizing a very-close protocol

Abstract Background Very high-power short-duration (vHP-SD) radiofrequency (RF) ablation of atrial fibrillation (AF) treatment by pulmonary vein isolation (PVI) aims for safer, more effective and faster procedures. The lesion formation of vHP-SD ablation creates wider but shallower lesions. Utilizing an individualized "very close-protocol" of 3-4mm inter-lesion distance (ILD) at the anterior and 5-6mm at the posterior aspect of the left atrium using vHP-SD only the close-protocol was adapted. Although acute efficacy for PVI was recently shown no data on chronic PVI durability has been assessed up to date. Here chronic PVI durability was evaluated during repeat electrophysiological procedures in patients after initial vHP-SD based PVI and recurrence of AF, atrial tachycardia or left atrial appendage closure. Methods and Results A total of 25 consecutive patients with repeat left atrial procedures after initial vHP-SD based PVI were included in this study. The median time to the repeat procedure was 5 (IQR 2, 10) months. The patients received a repeat procedure and verification of PVI due to recurrence of AF (n=8), atrial tachycardia (n=12), typical flutter (n=1) or left atrial appendage closure (n=4). During repeat procedures 3D electroanatomical mapping of the left atrium was conducted. Verified PVI durability of all PVs was found in 16/25 (64%) patients. In 1/25 (4%) patient PVI reconduction was found in 1 PV, in 6/25 (24%) patients PVI reconduction was found in 2 PVs and in 1/25 (4%) patient PVI reconduction was found in 3 PVs. A total of 81/100 PVs (81%) were found to be chronically isolated. For right sided PVs 42/50 PVs (84%) were isolated while for left sided PVs 39/50 PVs (78%) were isolated. All PVs were reisolated utilizing radiofrequency energy. Conclusions PVI solely utilizing vHP-SD via a very close-protocol provides high rates of chronically isolated pulmonary veins.

Abstract 12570: Catheter Ablation Rates for Typical Atrial Flutter in Military Tactical Athletes

Introduction: Cavotricuspid isthmus (CTI)-dependent atrial flutter is known to adversely impact exercise physiology and occupational readiness in active-duty military personnel. Despite guideline recommendations supporting catheter ablation for CTI-dependent flutter, there is a paucity of literature reporting the utilization and outcomes of catheter ablation in military personnel and other tactical athletes. Aims: This study aims to characterize United States military personnel diagnosed with CTI-dependent flutter and investigate the rates of catheter ablation and personnel returning to tactical athletic occupations. Methods: Military personnel diagnosed with CTI-dependent flutter from 2016 to 2022 were analyzed. Baseline clinical characteristics and typical flutter management was reviewed. CTI-flutter diagnoses were confirmed by electrocardiogram and electrophysiology study with entrainment or activation mapping. Results: During the study dates 40 military members (mean age, 40.7±10.7 years; 98% male; mean BMI 28.3±4.2 kg/m 2 ; mean LVEF 58.3%±7.7) were diagnosed with typical flutter. 34/40 (85%) of service members diagnosed with typical flutter were retained on military status after diagnosis. Of those retained, 13/34 (38.2%) were able to complete deployments. Electrophysiology study and successful CTI ablation was performed in 27/40 (67.5%) of personnel with zero complications. 26/27 (96.3%) servicemembers who underwent CTI ablation maintained their tactical occupation whereas only 8/13 (61.2%) service members who did not receive CTI ablation were retained (p=0.009). 10/27 (37.0%) who received CTI ablation were able to subsequently deploy whereas only 3/13 (23%) who did not receive CTI ablation were able to deploy (p=0.484). Conclusions: Most military tactical athletes with CTI-dependent flutter receive safe and effective CTI ablations. CTI ablation increases tactical occupation retention rates when compared to treatment without CTI ablation. This data supports the use of CTI ablation as first-line treatment for military personnel and highlights the role of increasing ablation rates in other similar athletic populations.

Abstract 16302: Beyond the Veins: A Critical Right Atrial Termination Site in High Burden Paroxysmal Atrial Fibrillation Identified Using Spatiotemporal Dispersion After Failure of High Quality Pulmonary Vein Isolation

Case Presentation: A 55 year-old female with two-year history of persistent atrial fibrillation (AF) presented for elective catheter ablation. Her smart watch recorded frequent prolonged episodes of AF, and event monitoring confirmed 71% AF burden. Metoprolol improved her symptoms only slightly. At the beginning of the procedure, patient’s rhythm was on sinus (NSR). During the completion of pulmonary vein isolation (PVI), the patient developed typical flutter, which degenerated into AF during ablation. Biatrial dispersion mapping in the right atrium (RA) revealed a single highly dispersed area in the posterior RA. Ablation at this site immediately terminated AF to NSR. The patient was non-inducible and remains free of AF. Discussion: Maintenance of NSR in AF is associated with improved clinical outcomes and quality of life. Catheter ablation has the highest efficacy for minimizing AF burden. PVI has a success rate of 67-89% in treating patients with paroxysmal AF and PVI alone is typically employed. A dispersion area is characterized by local clusters of electrograms which may or may not be fractionated, and display interelectrode time and space dispersion such that activation is spread over the entire AF cycle length. Identification and ablation of dispersion regions in persistent AF has demonstrated a high acute termination rate and improved outcomes in early follow-up, but is difficult to reproduce (Seitz et al. 2017). Here, we present a case of a patient with high burden paroxysmal AF who underwent PVI but remained in AF. Using visual dispersion mapping, we were able to identify a critical RA dispersion area, which rendered patient non-inducible (Figure 1).

Diagnosing Atypical Flutter in the Post-atrial Fibrillation Ablation Patient: A Case Report.

Late atrial arrhythmias after catheter ablation for atrial fibrillation occur in up to 30% of post-ablation patients and are increasingly encountered by emergency physicians. However, diagnosing the exact mechanism of the arrhythmia on the surface electrocardiogram (ECG) remains challenging due to atrial scarring leading to heterogeneous P-wave morphology. A 74-year-old male with a history of prior catheter ablation for atrial fibrillation presented with palpitations and subacute symptoms of heart failure. The patient's ECG revealed narrow complex tachycardia with more P waves than QRS complexes. The differential diagnosis included typical flutter, atypical flutter, and focal atrial tachycardias with 2:1 conduction block. P waves were positive in V1 and across all precordial leads (absent precordial transition). This favors atypical flutter originating from the left atrium over typical cavotricuspid isthmus-dependent right atrial flutter. Transthoracic echocardiogram showed a reduced ejection fraction due to tachycardia-mediated cardiomyopathy. The patient underwent a repeat electrophysiology study and ablation, which confirmed the presence of an atypical flutter circuit using the mitral annulus, known as perimitral flutter. Repeat catheter ablation resulted in maintenance of sinus rhythm. At follow-up, his ejection fraction recovered. Recognizing ECG findings suggestive of atypical flutter impacts initial emergency department decisions and triage as atypical flutter post-atrial fibrillation ablation is frequently resistant to rate-controlling medications and often requires cardiology and/or electrophysiology consultation if available.

One-year follow-up after pulmonary vein isolation using pulsed field ablation for paroxysmal atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) has recently been introduced as a novel routine ablation technology for paroxysmal atrial fibrillation (PAF). Only a few small clinical studies have been published on the mid- and long-term outcome. Here, we present the one-year clinical outcomes of PFA in PAF. Methods In PAF patients, PVI in conscious sedation using a steerable sheath and a pentaspline over-the-wire basket and flower PFA catheter was performed. In a subset of patients, pre- and post-ablation high-density bipolar voltage 3D maps using a pentaspline diagnostic cathter were performed. Procedural parameters, acute success, in-hospital safety and arrhythmia recurrence were assessed during one-year follow-up. Efficacy was evaluated by freedom from a ≥ 30-sec. recurrence of AF/atrial flutter (AFL)/atrial tachycardia (AT). Follow-up included 7-day Holter ECGs and/or telephonic interviews at days 90, 180 and 360 days after ablation. Results This study included a total of 108 patients (mean age 65±10 years; 44% female). Mean CHA2DS2-VASc-score was 2,3±1,7. Mean duration since first AF diagnosis was 45±63 months. Pre- and post-ablation high-density maps were performed in 36/108 (33%) of patients. Skin-to skin procedure time was 78±36 min. Fluoroscopy time and dose area product were 19±8 min and 5,56±4,64 Gy.cm2, respectively. Left atrial dwell time of the PFA catheter was 27±11 min. Acute PVI rate was 100% of PVs using PFA only. Primary adverse events occurred in 3,7% of patients (1 groin hematoma, 2 pericardial tamponades, 1 acute stroke with lethal outcome). No patients were lost during FU. During a mean FU of 346±64 days, 88 of 107 patients (82%) remained free of any symptomatic or documented AF/AFL/AT episode after a single procedure. After the 90-day blanking period, in 19 (18%) patients at least one episode of AF/AFL/AT was documented. In 14/107 (13%) patients, after 216±102 days a re-do procedure was performed. In 7/107 (7%) patients, PV reconduction was seen. In 5/107 (5%) patients, during re-do procedure clinical or induced typical or atypical flutter was treated in presence of durable PV isolation. In the remaining 2/107 (2%) patients, only clinical right atrial typical flutter was treated and no left atrial mapping was performed. Conclusions PVI using PFA in patients with a relatively long history of PAF results in a low one-year atrial arrhythmia recurrence rate. The success rate may be reduced due to the long duration since first AF diagnosis and the initial experience with PFA by the operators. PV reconduction rate during re-do procedure in a limited number of patients was 7%. There was a reasonable safety profile and it improved significantly over the course of time, indicating that the learning curve could have negatively influenced the incidence of complications. Figure: Kaplan-Meier analysis of freedom from atrial arrhythmias, including any AF/AFL/AT episode exceeding 30 sec. Not including the 3-month blanking period.

Pulsed field ablation for atrial tachycardia following prior persistent atrial fibrillation ablation and resistant to radiofrequency energy

Abstract Funding Acknowledgements Type of funding sources: None. Background There is a limited knowledge of immediate and long-term efficacy of pulsed field ablation for residual atrial tachycardia (AT) following (longstanding) persistent atrial fibrillation (AF) ablation and resistant to prior radiofrequency ablation (RFA). Purpose To present immediate effects of PFA (Farapulse) in a series of patients with repeat ablation for residual atrial tachycardia (AT) resistant to prior RFA. Methods and results In 5-11/2022, of 23 patients scheduled for PFA, 19 patients (64±7 years, 3 females) underwent PFA for left atrial (LA) AT resistant to RFA in first (n=4), second (n=11), third (n=3), and fourth (n=1) repeat ablation, respectively, after primary persistent AF ablation (4 patients were redirected to RFA for septal/right atrial AT source found by 3D mapping). At the procedure onset, persistent AT was ongoing (n=15) or was induced (n=4; AF induced and subsequently converted into AT in 3 patients). Mapping/ablation strategy was directed according to CS activation/entrainment to: 1) no 3D mapping and direct PFA (n=11); 2) PFA directly after 3D LA mapping (n=5); 3) PFA following RFA after 3D LA mapping (n=3). Total of 29 ATs was found (1,2, and 3 ATs in 12, 4, and 3 patients, respectively). Localized AT sources (n=16) dominated over macroreentry (MR) ATs (8 perimitral, 4 roof-dependent, 1 typical flutter). Only MR ATs, only localized ATs, and both MR+localized ATs were present in 7, 4, and 8 patients, respectively. All ATs were stopped with 5±9 PFA applications at the site of AT source and remained non-inducible. In 3 patients with initial ineffective RFA (6, 11, 6 minutes) within the same procedure, subsequent PFA terminated the AT with 1, 4, and 1 application respectively. Procedure and fluoroscopy times were 104±29 and 12±4 minutes, no complication occurred. Conclusion PFA with catheter Farapulse can affect complex/epicardial AT sources resistant to RFA in prior or present ablation procedure.

Six-month follow-up after pulmonary vein isolation using pulsed field ablation for paroxysmal atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) has recently been introduced as a novel routine ablation technology for paroxysmal atrial fibrillation (PAF). Only a few small clinical studies have been published on the mid- and long-term outcome. Herein, we present the six-month clinical outcomes of PFA in PAF. Methods In PAF patients, PVI in conscious sedation using a steerable sheath and a pentaspline over-the-wire basket and flower PFA catheter was performed. In a subset of patients, pre- and post-ablation high-density bipolar voltage 3D maps (Carto 3D) were performed. Procedural parameters, acute success, in-hospital safety and arrhythmia recurrence were assessed over 6-month follow-up. Efficacy was evaluated by freedom from a ≥ 30-sec. recurrence of AF/atrial flutter (AFL)/atrial tachycardia (AT). Follow-up included 7-day Holter ECGs and/or telephonic interviews at days 90 and 180 after ablation. Results his study included a total of 108 patients (mean age: 65±10 years; 44% female). Mean CHA2DS2-VASc-score was 2,3±1,7. Median duration since first AF diagnosis was 21 [IQR: 3 to 58] months. Pre- and post-ablation high-density maps were performed in 36/108 (33%) of patients. Skin-to skin procedure time was 78±35 min. Fluoroscopy time and dosis area product were 19±7 min and 5,56±4,64 Gy.cm2, respectively. Left atrial dwell time of the PFA catheter was 27±11 min. Acute pulmonary vein isolation rate was 100% of PVs using PFA only. Primary adverse events occurred in 3.7% of patients (1 groin hematoma, 2 pericardial tamponades, 1 stroke with lethal outcome). Five patients were lost to FU. During a mean FU of 205±84 days, 81 of 103 patients (79%) remained free of any symptomatic or documented AF/AFL/AT episode after a single procedure. In 22 (21%) patients at least one episode of AF/AFL/AT was documented. In 6/22 (27%) patients, a re-do procedure was performed. In 2/6 (33%) patients, a reconduction of the PVs (1 LIPV, 1 posterior carina on both sides) was seen. In the remaining 4/6 (67%) patients, during re-do procedure typical or atypical flutter was treated, in presence of durable PV isolation. Conclusions PVI using PFA results in a reasonable 6-month atrial arrhythmia recurrence rate and safety profile. The success rate may be reduced due to the long duration since first AF diagnosis. PV reconduction rate during re-do procedure was 33% in a limited number of patients.

PO-01-085 ATRIAL AND VENTRICULAR ARRHYTHMIAS IN A PATIENT WITH TUBEROUS SCLEROSIS

Tuberous Sclerosis is a genetic condition characterized with multiple non-cancerous tumor growths throughout the body. While arrhythmias are commonly seen in these patients, the predominance of arrhythmias appear to be irregular with atrial and ventricular ectopy as the most common manifestation. In our case we describe a patient with both organized atrial arrhythmias ( typical atrial flutter, atypical atrial flutter ) and monomorphic ventricular tachycardia. A pleasant 22 year old female with a pertinent medical history of Tuberous Sclerosis with multiple tubers present in the heart and brain presented to the electrophysiology clinic for evaluation regarding palpitations. The patient had a known history of prior ablation for typical atrial flutter twice before with recurrence of arrhythmias despite ablation and long term anti-arrhythmic therapy with flecainide. Implantation of an implantable loop recorder revealed evidence of likely typical flutter as well as monomorphic ventricular tachycardia. During the electrophysiology study, typical atrial flutter and atypical atrial flutter was succesfully induced and ablated. No ventricular arrhythmias could be induced. In addition intracardiac echocardiography revealed the presence of rhabdomyomas in the cavo-tricuspid isthmus and right side of the interventricular septum. NA Ablation across the CTI and a posterior line from the SVC to IVC resulted in tachycardia termination with no further induction of atrial arrhythmias and the presence of bidirectional block. No ventricular arrhythmias could be induced. Arrhythmias are a common manifestation in Tuberous Sclerosis. Our case highlights the arrhythmogenic nature of rhabdomyomas that can be present in both the atrium and ventricle. There is a scarcity of data available regarding the overall burden of arrhythmias in this patient population. In addition our patient is unique in that they presented with organized atrial and ventricular arrhythmias. The mechanism of the ventricular arrhythmia is unclear as it was not able to be induced, however, both atrial arrhythmias appeared macro-reentrant. While some histopathologic studies have suggested the presence of macro-renetrant circuits in this patient population, further large scale studies would be helpful to help characterize the mechanism of arrhythmias in this patient population.