Atrial Fibrillation Cycle Length Research Articles

Selective complex fractionated atrial electrogram ablation based on the number-of-fractionation for persistent atrial fibrillation refractory to pulmonary vein isolation.

Previous studies have suggested that the prolonged or highly fractionated electrograms during atrial fibrillation (AF) are closely related to the reentrant driver regions. We hypothesized that exploration and ablation of these critical complex atrial fractionated electrograms (CFAE) may improve the outcome of persistent AF (PeAF) refractory to conventional PVI. A total of 73 PeAF patients with residual inducibility or failed cardioversions of AF after PVI were enrolled and underwent number-of-fractionation mapping (NFM) by counting the number of fractionations in 2.5s at each of the points using the CARTO3 (ICL mode) and EnSite (fractionation map) systems. After NFM, selective CFAE ablation (NFM-CA) targeting the sites of the upper 40% of the counted fraction number (NF40) was performed as an additional procedure for refractory PeAF. We investigated the prognosis of these patients within 24months after the index ablation procedure and the relationship between changes in activation patterns during the ablation procedure and their prognosis. We also performed a propensity score-matched analysis comparing these patients with historical controls (HC) to identify the optimal indications for NFM-CA. The AF/AT free survival rate was 79.1% at 12months and 56.7% at 24months. Patients with AF termination or AF cycle length prolongation > 21ms during the procedure had significantly better AF/AT-free survival rates than those without notable activation changes (87.7% vs. 69.0%, logrank p = 0.028). After propensity-matched analysis, AF/AT-free survival showed comparable results between the two groups (1year; NFM 72.1% vs. HC 77.1%, logrank p = 0.649). NFM-CA is a versatile and less invasive adjunctive procedure for patients with PVI-refractory PeAF who showed a comparable prognosis to patients with PVI-compliant PeAF. In particular, remarkable activation changes during the procedure (AFCL prolongation > 21ms or acute termination) suggest a favorable prognosis.

Vein of Marshall chemical ablation decreases atrial fibrillation drivers detected by CARTOFINDER.

This study sought to elucidate the impact of vein of Marshall (VOM) chemical ablation on atrial fibrillation (AF) drivers by investigating the changes in CARTOFINDER mappings before and after VOM chemical ablation in patients with persistent AF. This study included 23 consecutive patients undergoing catheter ablation for long-persistent AF (>18 months). VOM chemical ablation was performed following pulmonary vein isolation. CARTOFINDER and AF cycle length (AFCL) maps were created in the left atrium (LA) before and after VOM chemical ablation. The LA was divided into 8 segments, and the number of focal activation points with 6 or more repetitions was counted in each segment. The number of focal activation points was largest in the LA appendage (LAA). After VOM chemical ablation, the number of focal activation points in the LA decreased significantly (37 [interquartile range, IQR: 19-55] vs. 15 [IQR: 7-21], p < .001), and median AFCL was significantly prolonged (159 [147-168] vs. 164 [150-173] ms, p < .001). In the assessment of each segment, significant decreases in focal activation points were observed in the inferior, lateral, and anterior segments and LAA. Among the focal activation points disappearing after chemical ablation, the number in the non-ethanol-affected area was significantly larger than that in the affected area (13 [8-25] vs. 4 [1-10], p < .001). VOM chemical ablation decreases AF drivers detected by CARTOFINDER. Mechanisms other than direct myocardial damage are considered to contribute the attenuation of AF drivers.

First clinical data on artificial intelligence-guided catheter ablation in long-standing persistent atrial fibrillation.

Despite advanced ablation strategies and major technological improvements, treatment of persistent atrial fibrillation (AF) remains challenging and the underlying pathophysiology is not fully understood. This study analyzed the multiple procedure outcome and safety of catheter ablation of spatiotemporal dispersions (DISPERS) detected by artificial intelligence (AI)-guided software in patients with long-standing persistent AF. The Volta VX1 software was used for 50 consecutive patients undergoing catheter ablation for persistent AF. First, high-density mapping (78% biatrial) with a multipolar mapping catheter was performed. In addition to pulmonary vein isolation (PVI), ablation of DISPERS was performed aiming at homogenizing, dissecting, isolating, or connecting DISPERS areas to nonconducting anatomical structures. Follow-up contained regular visits at our outpatient clinic at 1, 3, 6, and 12 months including 7-day Holter electrocardiograms. Patients were mainly suffering from long-standing persistent AF (mean AF duration 50.30 ± 54.28 months). Following PVI, ablation of left atrial and right atrial DISPERS areas led to AF cycle length prolongation (mean of 162.0 ± 16.6to 202.2 ± 21.6 ms after) and AF termination to atrial tachycardia (AT) or sinus rhythm (SR) in 12 patients (24%). No stroke or pericardial effusion occurred; major groin complications (pseudoaneurysm n = 1, atrioventricularfistula n = 1) were detected in two patients. After a blanking period of 6 weeks, recurrence of any atrial arrhythmia was documented in 26 patients (52%). The majority of patients presented with organized AT (n = 15) while AF was present in n = 9 patients and AT/AF was observed in n = 2 patients. Twenty-twopatients underwent reablation. During a mean follow-up of 363.14 ± 187.42 days and after an average of 1.46 ± 0.68 procedures, 82% of patients remained in stable SR. DISPERS-guided ablation using machine learning software (the Volta VX1 software) in addition to PVI in long-standing persistent AF ablation resulted in high long-term success rates regarding AF and AT elimination. Most arrhythmia recurrences were reentrant AT. After a total of 1.46 ± 0.68 procedures, freedom from AF/AT was 82%. Despite prolonged procedure times complication rates were low. Randomized studies are necessary to evaluate long-term efficacy of dispersion-guided ablation using AI.

Analysis of drug-induced and spontaneous cardioversions reveals similar patterns leading to termination of atrial fibrillation.

The mechanisms leading to the conversion of atrial fibrillation (AF) to sinus rhythm are poorly understood. This study describes the dynamic behavior of electrophysiological parameters and conduction patterns leading to spontaneous and pharmacological AF termination. Five independent groups of goats were investigated: (1) spontaneous termination of AF, and drug-induced terminations of AF by various potassium channel inhibitors: (2) AP14145, (3) PA-6, (4) XAF-1407, and (5) vernakalant. Bi-atrial contact mapping was performed during an open chest surgery and intervals with continuous and discrete atrial activity were determined. AF cycle length (AFCL), conduction velocity and path length were calculated for each interval, and the final conduction pattern preceding AF termination was evaluated. AF termination was preceded by a sudden episode of discrete activity both in the presence and absence of an antiarrhythmic drug. This episode was accompanied by substantial increases in AFCL and conduction velocity, resulting in prolongation of path length. In 77% ± 4% of all terminations the conduction pattern preceding AF termination involved medial to lateral conduction along Bachmann's bundle into both atria, followed by anterior to posterior conduction. This finding suggests conduction block in the interatrial septum and/or pulmonary vein area as final step of AF termination. AF termination is preceded by an increased organization of fibrillatory conduction. The termination itself is a sudden process with a critical role for the interplay between spatiotemporal organization and anatomical structure.

Comparison of additional ablation of spatio-temporal dispersion electrograms and low voltage area beyond pulmonary vein isolation in patients with persistent atrial fibrillation

Abstract Backgrounds Although strategies beyond extensive pulmonary vein isolation (EPVI) including low voltage zone (LVZ) ablation in patients with persistent atrial fibrillation (AF) have not yet been established, recent research showed that ablation targeting spatio-temporal dispersion electrograms (STDE) could achieve high AF-free survival. We hypothesized that EPVI plus STDE approach could reduce AF recurrence after catheter ablation of persistent AF. Purpose The purpose of this study is to assess the AF recurrence after the ablation in different two strategies. Methods We prospectively enrolled consecutive patients with persistent AF undergoing their first catheter ablation at our institution during July 2018 to March 2021. The ablation strategy was divided into 2 groups: 1) EPVI plus LVZ and 2) EPVI plus STDE ablation. STDE was defined as clusters of fractionated electrograms that displayed interelectrode time and space dispersion at a minimum of three adjacent bipolar electrodes such that activation spread over all the cycle length of AF. The definition of LVZ was bipolar amplitude of &amp;lt;0.5mV. Posterior wall isolation was performed if STDE or LVZ were broadly present in posterior wall. The primary endpoint was defined as AF recurrence after the ablation. The blanking period of 3 months was applied. Results Out of 138 patients (66±11 years, 108 men), 64 patients underwent EPVI plus LVZ and 74 EPVI plus STDE ablation. There was no difference in median AF duration (8 [interquartile range (IQR) 4-13] months vs. 12 [IQR 5-22] months; p=0.129) and left atrial volume (151 [IQR 115-168] ml vs. 151 [IQR 127-175] ml; p=0.239) between the two groups. The prevalence of concomitant hypertension (47% vs. 67%; p=0.024) and diabetes mellitus (24% vs. 42%; p=0.027) was lower in the STDE group than in the LVZ group. Posterior wall isolation was performed more frequently in the STDE group than in the LVZ group (38% vs. 19%; p=0.015). At 1 year follow-up, the STDE group achieved higher AF-free rate than the LVZ group (84% [95% confidence interval (CI), 73-91%] vs. 64% [95% CI 52-76%]; P=0.017). Multivariate Cox regression analysis demonstrated that not only AF duration (hazard ratio [HR] 1.03, 95% CI 1.01–1.04; p&amp;lt;0.001), and left atrial volume (HR 1.10, 95% CI 1.02–1.19; p=0.011) but also STDE ablation (HR 0.33, 95% CI 0.14-0.77%, p=0.010) were independently associated with AF recurrence. Conclusions Ablation guided by STDE in addition to EPVI may be a useful treatment strategy for persistent AF.

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).

Atrial fibrillation cycle-length (AF-CL) inside the pulmonary veins predicts paroxysmal AF ablation success- the INDUCE-AF study.

A novel method to measure atrial fibrillation cycle length (AF-CL) was recently described, based on the average of 10 consecutive signals (FARS10). FARS10 accurately identified pulmonary vein isolation (PVI)-responders among patients with persistent AF. Whether this method is applicable to patients with paroxysmal AF is unknown. The aim of this study is to evaluate the prognostic value of FARS10 measurements in patients with paroxysmal AF. We enrolled paroxysmal AF patients undergoing PVI in a prospective multicenter study. After AF induction with a standardized protocol, the AF-CL was measured using FARS-10 method. The primary endpoint was AF/AT-recurrence. One-hundred and four patients were included (61 ± 14years, 25% females). After a mean follow-up of 12 ± 4months, AF/AT recurrence rate was 20%. The fastest PV CL (fPV-CL) was independently associated with the primary endpoint at multivariate analysis (HR 1.02, p < 0.001). Every 10ms increase in fPV-CL, AF recurrences increased by 20%. The value of 160ms was found to be the optimal cut-off (specificity 81%, sensitivity 76%). Patients with fPV-CL < 160ms experienced lower AF recurrences as compared to patients with fPV-CL > 160ms (8% vs. 32% at 1year; HR = 0.17, p < 0.001). Progression to persistent AF was observed in 13% of patients with fPV-CL > 160ms. fPV-CL measured with the FARS-10 method accurately predicts PVI success in paroxysmal AF patients undergoing PVI. Patients with slow PV activity (fPV-CL > 160ms) experience higher AF recurrence rate after PVI and more frequent progression to persistent AF.

Detection of the most dominant drivers of atrial fibrillation based on repetitive activity in sequential electro-anatomical mapping

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work is part of Personalize AF. This project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 860974, This work was also supported by the Swiss National Supercomputing Centre (CSCS), project s1074. Introduction Detecting and targeting the most dominant drivers of atrial fibrillation (AF) might improve the outcome of AF ablation procedures. We hypothesize that dominant drivers entrain their vicinity in a temporally and spatially stable manner resulting in local as well as adjacent repetitive activation patterns. Purpose We present a novel approach to detect the most dominant drivers of AF based on driver repetitiveness and the degree to which they entrain their vicinity. Methods We retrospectively analyzed a dataset of high-density bi-atrial sequential mapping in ablation-naive persistent AF patients (n=13, 30s recording per site). Candidate drivers (focal activity or re-entry) were detected based on local activation time analysis of unipolar electrograms. Focal activity was defined as radial spread of activation, re-entry as a circular activation sequence on at least 4 splines of the mapping catheter that covered &amp;gt;50% of the AF cycle length. As a measure of driver stability, we determined the driver's local repetitiveness (in % of recording). As a measure of driver-associated entrainment, we determined the directionally coherent repetitiveness of adjacent recordings within 30 mm (Figure 1). Following our hypothesis, most dominant drivers can be recognized by their high local and directional coherent adjacent repetitiveness. Results A total of 459 recordings were analyzed (35±5 per patient). We detected 130 focal activities (10±3 per patient) and 42 re-entries (4±2 per patient) in total. The spatial distribution of all drivers is shown in Figure 2 (blue bars). Focal activities were more repetitive than re-entries (Figure 2, median [IQR] 3.2% [1.9%, 5.6%] vs. 1.8% [1.8%, 2.2%], p&amp;lt;0.001 Mann-Whitney U-test). When applying a 90th percentile threshold (8.2%) to both the local and directional coherent adjacent repetitiveness to detect the most dominant drivers, we were able to detect 9 dominant drivers (all focal activities, 7 patients). Most dominant drivers were located in the upper right atrium or left pulmonary vein region (Figure 2). Interestingly, only 9 of the 130 initially detected drivers (7%) showed an activation pattern in line with a repetitive entrainment of their vicinity. Furthermore, in 6 patients (46%), no dominant drivers were detected. This might indicate that not all patients have temporally and spatially stable drivers. Conclusion In this abstract we present a novel methodology to detect the most dominant drivers of AF. Using this method, we found that some (but not all) patients have temporally and spatially stable drivers that are able to entrain their vicinity.

Targeted ablation of arrhythmogenic substrate in complex cases of very long-standing persistent atrial fibrillation: successful ablation of spatio-temporal dispersions

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In persistent AF, outcomes after PVI alone is worse as the pathophysiology remains unclear. Prolonged AF duration is an independent predictor for worse success rates after catheter ablation. In this study, we investigated efficacy and safety of ablation of spatio-temporal dispersions, as additional ablation strategy after PVI in patients with long-standing persistent AF. Methods All consecutive patients with long-standing persistent AF treated with an AI-based algorithm for detection of spatio-temporal dispersion in our institution between 05/21 and 10/22 were included (n = 41, see table 1). The procedure was done using a high-density 3D-Map and an algorithm for detection of right and left atrial areas with spatio-temporal dispersion (DISPERS). Ablation of DISPERS was aiming at homogenizing, dissecting, isolating or connecting DISPERS areas to non-conducting structures. Follow-up contained regular visits at our out-patient-clinic and repetitive 7 day Holter ECGs. Late recurrence (LR) was defined as recurrence after 90 days or as recurrence, which caused further ablation. All complications requiring intervention or causing long-term sequelae were classified as major complications. Results In 24/41 pts (58.5%), the DISPERS guided ablation was the first AF ablation. Patients were suffering from very long-standing persistent AF with a mean AF duration of 64.89 ± 54.77 months. Additional to circumferential PVI, ablation of all detected left atrial (100%) and right atrial (68.3%) DISPERS areas was performed, leading to significant slowing of AF cycle length (mean 23.3%) or termination of AF to AT (5/41, 12.2%) or direct conversion to SR (6/41, 14.6%). One major complication occurred (1/41 (2.4%), pseudoaneurysm, resolving after manual compression). Three patients (7.3%) required temporary external pacing due to delayed sinus recovery after the procedure. No patient was in need of permanent pacemaker implantation. LR occurred in 25 patients (61.0 %): In 8/25 patients (32 %), LR was solely AF, whereas in 15/25 patients (60%) LR was a left AFlutt. In 2 patients (8%), AF and left AFlutt was detected. During a follow-up of 231 ± 129 days, 72.9 % of patients remained in sinus rhythm undergoing 1.6 ± 0.68 ablations (s. Figure 1; 4,9% of patients on AAD). Additionally, Figure 2 illustrates the AF-free outcome in all patients. Conclusion Ablation of arrhythmogenic substrate identified by spatio-temporal dispersion yielded in this cohort of extensively long-standing persistent AF patients in high success rates regarding elimination of AF. Most arrhythmia recurrences were reentrant AT. After a total of 1.6 procedures, freedom from AF and AT was &amp;gt;72%. Despite prolonged procedure times, complication rates remained very low. Extending study population and follow-up is needed to evaluate long-term efficacy of dispersion-guided ablation.

PO-01-162 INFLUENCE OF POSTERIOR WALL ACTIVITY ON AF ABLATION OUTCOMES: A CAPLA SUBSTUDY

A randomised trial (CAPLA study) of pulmonary vein isolation (PVI) vs empiric PVI + posterior wall isolation (PWI) did not improve AF outcomes in catheter ablation for persistent AF (PsAF). However PV and/or PW electrogram characteristics may identify a subset of patients in whom additional PWI is beneficial. To determine whether PV or PW AF cycle length predicts ablation outcomes in PVI with or without PWI for PsAF. Consecutive participants in spontaneous AF at the time of ablation were enrolled as part of the CAPLA study. PV, PW and left atrial appendage (LAA) cycle length (CL) were measured (longest, shortest, median) using a multipolar catheter for 100 consecutive cycles. We then evaluated the long-term impact of PV and PW CL on AF recurrence at 12 months follow up using twice daily ECG transmissions. 120 participants (24% female, 66±10 years, 20% LsPsAF, mean LAVI 52.4±15.7ml/m2, mean duration of continuous AF 8.6±10.0 months) were randomised to PVI alone (47.5%) vs PVI+PWI (52.5%) groups. Baseline clinical and echocardiographic characteristics were similar between groups (all p>0.05). Mean PV and PW CL were similar between groups (184±23 vs 176±21ms in PVI+PWI, p=0.053 and 180±21 vs 173±19ms p=0.082, respectively) with no difference in AF recurrence (54% in PVI vs 58% in PVI+PWI, Log Rank p =0.74. Shortest PW activity was independently associated with AF recurrence (HR 1.72 95% CI 1.24-4.23, p=0.040), whereas the presence of PV AF (p=0.14), PVCL (individual PVs or average of all 4 PVs) and PVCL heterogeneity were not (all p>0.05) regardless of ablation strategy. The addition of PWI was associated with greater arrhythmia-free survival (LogRank p=0.017, figure 1) in those with shorter PW activity (based on median PW<140ms). Short CL PW activity is associated with increased risk of AF recurrence post catheter ablation. The addition of PWI to PVI improved freedom from AF in the subset of patients with persistent AF with rapid PW activity.

Small solitary atrial fractionated electrogram zone as a novel ablation target for persistent atrial fibrillation.

Various adjunctive approaches to pulmonary vein isolation (PVI) have been attempted for persistent atrial fibrillation (perAF) and longstanding persistent AF (ls-perAF). We aimed to identify the novel zones responsible for perpetuation of AF. To identify novel zones acting as a source of perAF and ls-perAF after PVI/re-PVI,we performed fractionation mapping in 258 consecutive patients with perAF (n = 207) and ls-perAF (n = 51) in whom PVI/re-PVI failed to restore sinus rhythm. In 15 patients with perAF (5.8%: 15/258), fractionation mapping identified a small solitary zone (<1 cm2 ) with high-frequency and irregular waves, showing fractionated electrograms (EGM). We defined this zone as the small solitary atrial fractionated EGM (SAFE) zone. The small SAFE zone was surrounded characteristically by a homogeneous area showing relatively organized activation with nonrapid and nonfractionated waves. Only one small SAFE zone was detected in each patient. This characteristic electrical phenomenon was observed stably during the procedure until ablation. AF duration, (defined as the duration between initial detection of AF and the current ablation) was longer in patients with the small SAFE zone than in those without (median, [25 and 75 percentiles]; 5.0[3.5, 7.0] vs. 1.1 [1.0, 4.0] years, p = .0008). Longer AF cycle length was observed in patients with the small SAFE zone than in those without. The ablation of the small SAFE zone terminated AF in all 15 patients without any need for other ablations. AF/atrial tachycardia-freerate at follow-up was 93% (14/15) at 6 months, 87% (13/15) at 1 year, and 60% (9/15) at 2 years. Using fractionation mapping, this study identified a small SAFE zone surrounded characteristically by a homogeneous, relatively organized, low-excitability EGM lesion. The ablation of the small SAFE zone terminated AF in all patients, demonstrating it as a substrate for perpetuated AF. Our findings provide novel ablation targets in perAF patients with prolonged AF duration. Further studies to confirm the present results are warranted.

Organization of atrial fibrillation using a pure sodium channel blocker: Implications of rotor ablation therapy.

Rotors are the source of atrial fibrillation (AF). However, the ablation of rotors for persistent AF is challenging. The purpose of this study was to identify the dominant rotor by accelerating the organization of AF using a sodium channel blocker and detecting the rotor's preferential area that governs AF. Overall, 30 consecutive patients with persistent AF who underwent pulmonary vein isolation and still sustained AF were enrolled. Pilsicainide 50 mg was administered. An online real-time phase mapping system (ExTRa Mapping™) was used to identify the meandering rotors and multiple wavelets in 11 left atrial segments. The time ratio of non-passive activation (%NP) was evaluated as the frequency of rotor activity in each segment. Conduction velocity became slower-from 0.46 ± 0.14 to 0.35 ± 0.14 mm/ms (p = .004)-and the rotational period of the rotor was significantly prolonged-156 ± 21 to 193 ± 28 ms/cycle (p < .001). AF cycle length was prolonged from 169 ± 19 to 223 ± 29 ms (p < .001). A decrease in %NP was observed in seven segments. Additionally, 14 patients had at least one complete passive activation area. Of them, the use of high %NP area ablation resulted in atrial tachycardia and sinus rhythm in two patients each. A sodium channel blocker organized persistent AF. In selective patients with a wide organized area, high %NP area ablation could convert AF into atrial tachycardia or terminate AF.

Abstract 15706: Non-Invasive 3D Electromechanical Cycle Length Mapping for Macroreentrant Atrial Flutter Characterization

Introduction: Arrhythmia localization prior to catheter ablation is critical for clinical decision making. The current standard of 12-lead EKG interpretation lacks spatial specificity and is anatomically limited. Electromechanical Cycle Length mapping (ECLM) is a high frame rate, echocardiography-based frequency analysis mapping technique, that can noninvasively map, localize and characterize cardiac activation frequencies in 3D. Hypothesis: Accurate localization prior to ablation may facilitate pre-op planning, reduce procedural times and fluoroscopic exposure. In this study we access ECLM feasibility for 3D mapping and quantifying macroreentrant atrial flutter (AFL) activation rates. Methods: Four patients (N = 4; 65 ± 9yo; 3 M) presented with AFL and were referred to RF ablation. Patients underwent pre-op transthoracic ECLM with simultaneous 3-lead EKG. 3D atrial ECLM cycle length (CL) maps were rendered and areas with arrhythmic CL were identified (100-330 ms). ECLM AFL and Ventricular CLs were defined as the dominant CL of the arrhythmic region and the region that remains synchronized with the ventricular activation respectively. ECLM findings were compared against identified origins and CLs on intracardiac electroanatomic mapping (EAM). Results: ECLM successfully identified and localized the presence of atrial typical CTI flutter in all four subjects when compared against successful RF ablation. An ECLM map in a CTI AFL case is shown on Fig. 1a with the CTI circuit in the right atrium. ECLM CLs exhibited excellent agreement with both the CL of the 3-lead EKG (Atrial CL: r 2 = 0.91, Ventricular CL r 2 = 0.99) and the EAM AFL CL (r 2 = 0.92). Conclusions: ECLM can localize, map and quantify the electromechanical CLs in AFL in excellent agreement with the clinical electrical CL rates and propagation patterns obtained by clinical albeit invasive procedures, providing thus a clinical noininvasive, non-ionizing mapping tool for RF ablation planning.

Practical Considerations for the Application of Nonlinear Indices Characterizing the Atrial Substrate in Atrial Fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and in response to increasing clinical demand, a variety of signals and indices have been utilized for its analysis, which include complex fractionated atrial electrograms (CFAEs). New methodologies have been developed to characterize the atrial substrate, along with straightforward classification models to discriminate between paroxysmal and persistent AF (ParAF vs. PerAF). Yet, most previous works have missed the mark for the assessment of CFAE signal quality, as well as for studying their stability over time and between different recording locations. As a consequence, an atrial substrate assessment may be unreliable or inaccurate. The objectives of this work are, on the one hand, to make use of a reduced set of nonlinear indices that have been applied to CFAEs recorded from ParAF and PerAF patients to assess intra-recording and intra-patient stability and, on the other hand, to generate a simple classification model to discriminate between them. The dominant frequency (DF), AF cycle length, sample entropy (SE), and determinism (DET) of the Recurrence Quantification Analysis are the analyzed indices, along with the coefficient of variation (CV) which is utilized to indicate the corresponding alterations. The analysis of the intra-recording stability revealed that discarding noisy or artifacted CFAE segments provoked a significant variation in the CV(%) in any segment length for the DET and SE, with deeper decreases for longer segments. The intra-patient stability provided large variations in the CV(%) for the DET and even larger for the SE at any segment length. To discern ParAF versus PerAF, correlation matrix filters and Random Forests were employed, respectively, to remove redundant information and to rank the variables by relevance, while coarse tree models were built, optimally combining high-ranked indices, and tested with leave-one-out cross-validation. The best classification performance combined the SE and DF, with an accuracy (Acc) of 88.3%, to discriminate ParAF versus PerAF, while the highest single Acc was provided by the DET, reaching 82.2%. This work has demonstrated that due to the high variability of CFAEs data averaging from one recording place or among different recording places, as is traditionally made, it may lead to an unfair oversimplification of the CFAE-based atrial substrate characterization. Furthermore, a careful selection of reduced sets of features input to simple classification models is helpful to accurately discern the CFAEs of ParAF versus PerAF.

Evaluation and optimization of novel extraction algorithms for the automatic detection of atrial activations recorded within the pulmonary veins during atrial fibrillation

Background and objectiveThe automated detection of atrial activations (AAs) recorded from intracardiac electrograms (IEGMs) during atrial fibrillation (AF) is challenging considering their various amplitudes, morphologies and cycle length. Activation time estimation is further complicated by the constant changes in the IEGM active zones in complex and/or fractionated signals. We propose a new method which provides reliable automatic extraction of intracardiac AAs recorded within the pulmonary veins during AF and an accurate estimation of their local activation times.MethodsFirst, two recently developed algorithms were evaluated and optimized on 118 recordings of pulmonary vein IEGM taken from 35 patients undergoing ablation of persistent AF. The adaptive mathematical morphology algorithm (AMM) uses an adaptive structuring element to extract AAs based on their morphological features. The relative-energy algorithm (Rel-En) uses short- and long-term energies to enhance and detect the AAs in the IEGM signals. Second, following the AA extraction, the signal amplitude was weighted using statistics of the AA sequences in order to reduce over- and undersensing of the algorithms. The detection capacity of our algorithms was compared with manually annotated activations and with two previously developed algorithms based on the Teager–Kaiser energy operator and the AF cycle length iteration, respectively. Finally, a method based on the barycenter was developed to reduce artificial variations in the activation annotations of complex IEGM signals.ResultsThe best detection was achieved using Rel-En, yielding a false negative rate of 0.76% and a false positive rate of only 0.12% (total error rate 0.88%) against expert annotation. The post-processing further reduced the total error rate of the Rel-En algorithm by 70% (yielding to a final total error rate of 0.28%).ConclusionThe proposed method shows reliable detection and robust temporal annotation of AAs recorded within pulmonary veins in AF. The method has low computational cost and high robustness for automatic detection of AAs, which makes it a suitable approach for online use in a procedural context.

Impact of Adenosine on Wavefront Propagation in Persistent Atrial Fibrillation: Insights From Global Noncontact Charge Density Mapping of the Left Atrium.

BackgroundAdenosine shortens action potential duration and refractoriness and provokes atrial fibrillation. This study aimed to evaluate the effect of adenosine on mechanisms of wavefront propagation during atrial fibrillation.Methods and ResultsThe study included 22 patients undergoing catheter ablation for persistent atrial fibrillation. Left atrial mapping was performed using the AcQMap charge density system before and after administration of intravenous adenosine at 1 or more of 3 time points during the procedure (before pulmonary vein isolation, after pulmonary vein isolation, and after nonpulmonary vein isolation ablation). Wave‐front propagation patterns were evaluated allowing identification and quantification of localized rotational activation (LRA), localized irregular activation, and focal firing. Additional signal processing was performed to identify phase singularities and calculate global atrial fibrillation cycle length and dominant frequency. A total of 35 paired maps were analyzed. Adenosine shortened mean atrial fibrillation cycle length from 181.7±14.3 to 165.1±16.3, (mean difference 16.6 ms; 95% CI, 11.3–21.9, P<0.0005) and increased dominant frequency from 6.0±0.7 Hz to 6.6±0.8 Hz (95% CI, 0.4–0.9, P<0.0005). This was associated with a 50% increase in the number of LRA occurrences (16.1±7.6–24.2±8.1; mean difference 8.1, 95% CI, 4.1–12, P<0.0005) as well as a 20% increase in the number of phase singularities detected (30.1±7.8–36.6±9.3; mean difference 6.5; 95% CI, 2.6–10.0, P=0.002). The percentage of left atrial surface area with LRA increased with adenosine and 42 of 70 zones (60%) with highest density of LRA coincided with high density LRA zones at baseline with only 28% stable across multiple maps.ConclusionsAdenosine accelerates atrial fibrillation and promotes rotational activation patterns with no impact on focal activation. There is little evidence that rotational activation seen with adenosine represents promising targets for ablation aimed at sites of stable arrhythmogenic sources in the left atrium.

Atrial Fibrillation Global Changes after Pulmonary Vein and Posterior Wall Isolation: A Charge Density Mapping Study.

Background: Non-contact charge density (CD) mapping allows a global visualization of left atrium (LA) activation and of activation patterns during atrial fibrillation (AF). The aim of this study was to analyze, with CD mapping, the changes in persistent AF induced by pulmonary vein isolation (PVI) and LA posterior wall isolation (LAPWI). Methods: Patients undergoing PVI + LAPWI using the Arctic Front Advance PROTM cryoballoon system were included in the study. CD maps were created during AF at baseline, after PVI and after LAPWI. Three distinct activation patterns were identified in the CD maps: localized irregular activation (LIA), localized rotational activation (LRA) and focal centrifugal activation (FCA). LA maps were divided into the following regions: anterior, septal, lateral, roof, posterior, inferior. Results: Eleven patients were included, with a total of 33 maps and 198 AF regions analyzed. Global and regional AF cycle lengths significantly increased after PVI and LAPWI. Baseline analysis demonstrated higher LIA, LRA and FCA numbers in the posterior and anterior regions. After PVI, there was no change in LIA, LRA and FCA occurrence. After PVI + LAPWI, a significant decrease in LRA was observed with no difference in LIA and FCA occurrence. In the regional analysis, there was a significant reduction in the LIA number in the inferior region, in the LRA number in the roof and posterior regions and in the FCA number in the lateral region. Conclusions: A global reduction in the LRA number was observed only after PVI + LAPWI; it was driven by a reduction in rotational activity in the roof and posterior regions.

Reproducibility and stability of atrial fibrillation drivers identified by an automated algorithm: CARTOFINDER.

The characteristics of atrial fibrillation (AF) drivers identified by CARTOFINDER have not been thoroughly evaluated. Therefore, the current study was sought to validate the reliability of AF drivers. The reliability of focal and rotational activation identified by CARTOFINDER during AF was assessed by the sequential recordings in each site before and after pulmonary vein isolation (PVI) in 27 persistent AF patients. The primary outcome measures were the reproducibility rate during the sequential recordings and the stability rate between pre- and post-PVI. Among 32,135 points in 509 sites, focal activation was identified in 1775 points (5.5%) with a repetition of 11 (6-26) times during the recording. Rotational activation was identified in 132 points (0.4%) with a repetition number of 21 (14-21) times. AF drivers had significantly higher voltage and shorter AF cycle length than non-AF driver sites. The reproducibility rate of focal activation during the sequential recordings was 57.8% and increased with the repetition number. The reproducibility rate of rotational activation was 37.4%. The prevalence and the reproducibility rate of focal activation in post-PVI were significantly lower than pre-PVI (5.3% versus 6.0%, P = 0.02; 53.4% versus 63.6%, P < 0.001). The stability rate of focal activation between pre- and post-PVI was only 28.3% but increased with the repetition number. There was no stable rotational activation between pre- and post-PVI. The reproducibility of AF drivers, especially focal activation, identified by CARTOFINDER is relatively favorable, but the stability between pre- and post-PVI was poor. These results depended on the repetition number during the recording.

Relationship between electrical activity and left atrial volume during atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Pulmonary veins (PV) ostia were previously identified as the left atrium (LA) areas with the shortest refractory period during sinus rhythm. Pulmonary veins isolation (PVI) became standard of care, but clinical results are still suboptimal. Currently, atrial fibrillation (AF) cycle length mapping (CLM) is possible due to a special tool of the Carto® electroanatomical mapping, which identifies areas in the left atria with shortest refractory period, during AF. Purpose Using this new EAM feature, our study aimed to assess the relationship between short refractory period LA areas and left atrial volume and AF type, known predictors of AF relapse. Methods Retrospective analysis of an unicentric registry of individuals with symptomatic drug-refractory AF who underwent PVI AF ablation with Carto® EAM. CLM was performed. CL maps were created with a high-density mapping Pentaray® catheter before and after PVI. We assessed areas of short cycle length (SCL) (defined as 120 to 250ms), and their relationships with complex fractionated atrial electrograms (CFAE), and low-voltage zones (from 0.1 to 0.3mV). Results A total of 35 patients (21 men, median age 62 IQR 53-71 years) were included. Most patients presented with persistent AF (n=23, 66%), and 8 patients (23%) had a previous PVI. The mean shortest measured cycle length in AF was 134ms (SD ± 23ms). There was a negative correlation between LA volume and SCL areas after PVI (Spearman Correlation coefficient [ρ] = - 0.47, P = 0.037). There was no correlation between LA volume and SCL areas before the PVI procedure (ρ = -0.06, P = 0.776), nor between AF type and SCL (ρ = -0.118, P = 0.620). All patients presented areas of SCL located in the PVs or their insertion, 76% in the posterior/roof region adjacent to the left superior pulmonary vein (LSPV) and 76% in the anterior region of the wall adjacent to the right superior pulmonary vein (RSPV). These two areas remained the fastest even after PVI. The anterior mitral region rarely presented SCL (16%). SCL were related to low-voltage areas in 93% and were adjacent to CFAE in 84% of the cases. Low-voltage areas and CFAE were more frequent and had a larger LA dispersion than SCL. Conclusion Our study shows that LA volume, not AF type, is correlated with remaining SCL areas after a pulmonary vein isolation procedure. This finding suggests a possible causal link between increased LA volume and AF relapse post-PVI. More studies are needed to assess the role of the SCL areas as a potential ablation target and their impact on AF ablation outcomes.

Correlation between sinus rhythm deceleration zones and critical sites for localized reentrant atrial flutter: A retrospective multicenter analysis.

BackgroundAtypical left atrial flutter (AFL) may be macroreentrant or spatially localized. The relationship between the critical isthmus (CI) for localized reentry with sinus rhythm (SR) conduction slowing has not been systematically examined.ObjectiveTo examine the correlation between CI sites for localized AFL (L-AFL) and deceleration zones (DZ) identified by isochronal late activation mapping (ILAM) during baseline rhythm.MethodsPatients with localized AFL who underwent high-density activation mapping of both SR and AFL were retrospectively analyzed. L-AFL was defined as reentry restricted to 2 wall segments of the left atrium. CI was defined by activation mapping and sites of successful termination during ablation. DZ, defined as >3 isochrones within 1 cm radius during baseline rhythm, were correlated to the locations of the CI.ResultsThirty-one consecutive patients that underwent detailed sinus rhythm and AFL high-density activation maps were analyzed at 3 centers. A mean 4060 ± 3275 and 6209 ± 8656 points were collected in ILAM and AFL activation maps, respectively. At least 1 DZ (1.7 ± 0.77) was identified in all patients. ILAM showed 3.27 ± 0.52 isochrones per DZ (168 ± 32 ms), and co-localized to CI sites at a distance of 6.7 ± 3 mm. A total of 34% ± 14% of the AFL cycle length was contained within 0.5 cm of the DZ.ConclusionsIn patients with L-AFL, CI co-localized with DZ during baseline rhythm, suggesting that DZ mapping during SR may yield candidate targets for ablation as an adjunct to pulmonary vein isolation to prevent a subtype of AFL.