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Aims: Duty-cycled radiofrequency ablation (RFA) has been used for atrial fibrillation (AF) for around 5 years, but large-scale data are scarce. The purpose of this survey was to report the outcome of the technique., Methods and Results: A survey was conducted among 20 centres from seven European countries including 2748 patients (2128 with paroxysmal and 620 with persistent AF). In paroxysmal AF an overall success rate of 82% [median 80%, interquartile range (IQR) 74-90%], a first procedure success rate of 72% [median 74% (IQR 59-83%)], and a success of antiarrhythmic medication of 59% [median 60% (IQR 39-72%)] was reported. In persistent AF, success rates were significantly lower with 70% [median 74% (IQR 60-92%)]; P = 0.05) as well as the first procedure success rate of 58% [median 55% (IQR 47-81%)]; P = 0.001). The overall success rate was similar among higher and lower volume centres and were not dependent on the duration of experience with duty-cycled RFA (r = -0.08, P = 0.72). Complications were observed in 108 (3.9%) patients, including 31 (1.1%) with symptomatic transient ischaemic attack or stroke, which had the same incidence in paroxysmal and persistent AF (1.1 vs. 1.1%) and was unrelated to the case load (r = 0.24, P = 0.15), bridging anticoagulation to low molecular heparin, routine administration of heparin over the long sheath, whether a transoesophageal echocardiogram was performed in every patient or not and average procedure times., Conclusion: Duty-cycled RFA has a self-reported success and complication rate similar to conventional RFA. After technical modifications a prospective registry with controlled data monitoring should be conducted to assess outcome.

Purpose: Several studies have emphasised the significance of high dominant frequency (HDF) and rotors in the perpetuation of AF. However, the colocalisation relationship between both attributes is not completely understood yet. In this study, we aim to evaluate the spatial distributions of HDF regions and rotor sites within the left atrium (LA) pre and post HDF-guided ablation in PersAF. Methods: This study involved 10 PersAF patients undergoing catheter ablation targeting HDF regions in the LA. 2048-channels of atrial electrograms (AEG) were collected pre-and post-ablation using a non-contact array (EnSite, Abbott). The dominant frequency (DF, 4-10 Hz) areas with DF within 0.25 Hz of the maximum out of the 2048 points were defined as "high" DF (HDF). Rotors were defined as PSs that last more than 100 ms and at a similar location through subsequent phase frames over time. Results: The results indicated an extremely poor spatial correlation between the HDF regions and sites of the rotors in pre-versus post-ablation cases for the non-terminated (pre: CORR; 0.05 ± 0.17. vs. post: CORR; -0.030 ± 0.19, and with terminated patients (pre: CORR; -0.016 ± 0.03. post: CORR; -0.022 ± 0.04). Rotors associated with AF terminations had a long-lasting life-span postablation (non-terminated vs. terminated 120.7 ± 6.5 ms vs. 139.9 ± 39.8 ms), high core velocity (1.35 ± 1.3 mm/ms vs. 1.32 ± 0.9 mm/ms), and were less meandering (3.4 ± 3.04mmvs. 1.5 ± 1.2 mm). Although the results suggest a poor spatial overlapping between rotors' sites and sites of AFCL changes in terminated and non-terminated patients, a higher correlation was determined in terminated patients (spatial overlapping percentage pre: 25 ± 4.2% vs. 17 ± 3.8% vs. post: 8 ± 4.2% vs. 3.7 ± 1.7% p < 0.05, respectively). Conclusion: Using non-contact AEG, it was noted that the correlation is poor between the spatial distribution of HDF regions and sites of rotors. Rotors were longer-lasting, faster and more stationary in patients with AF termination postablation. Rotors sites demonstrated poor spatial overlapping with sites of AFCL changes that lead to AF termination. [ABSTRACT FROM AUTHOR]

Purpose: Sites of highest dominant frequency (HDF) are implicated by many proposed mechanisms underlying persistent atrial fibrillation (persAF). We hypothesized that prospectively identifying and ablating dynamic left atrial HDF sites would favorably impact the electrophysiological substrate of persAF. We aim to assess the feasibility of prospectively identifying HDF sites by global simultaneous left atrial mapping. Methods: PersAF patients with no prior ablation history underwent global simultaneous left atrial non-contact mapping. 30 s of electrograms recorded during AF were exported into a bespoke MATLAB interface to identify HDF regions, which were then targeted for ablation, prior to pulmonary vein isolation. Following ablation of each region, change in AF cycle length (AFCL) was documented (≥ 10 ms considered significant). Baseline isopotential maps of ablated regions were retrospectively analyzed looking for rotors and focal activation or extinction events. Results: A total of 51 HDF regions were identified and ablated in 10 patients (median DF 5.8Hz, range 4.4–7.1Hz). An increase in AFCL of was seen in 20 of the 51 regions (39%), including AF termination in 4 patients. 5 out of 10 patients (including the 4 patients where AF termination occurred with HDF-guided ablation) were free from AF recurrence at 1 year. The proportion of HDF occurrences in an ablated region was not associated with change in AFCL (τ = 0.11, p = 0.24). Regions where AFCL decreased by 10 ms or more (i.e., AF disorganization) after ablation also showed lowest baseline spectral organization (p < 0.033 for any comparison). Considering all ablated regions, the average proportion of HDF events which were also HRI events was 8.0 ± 13%. Focal activations predominated (537/1253 events) in the ablated regions on isopotential maps, were modestly associated with the proportion of HDF occurrences represented by the ablated region (Kendall's τ = 0.40, p < 0.0001), and very strongly associated with focal extinction events (τ = 0.79, p < 0.0001). Rotors were rare (4/1253 events). Conclusion: Targeting dynamic HDF sites is feasible and can be efficacious, but lacks specificity in identifying relevant human persAF substrate. Spectral organization may have an adjunctive role in preventing unnecessary substrate ablation. Dynamic HDF sites are not associated with observable rotational activity on isopotential mapping, but epi-endocardial breakthroughs could be contributory. [ABSTRACT FROM AUTHOR]

Objective: Ablation treatment for persistent atrial fibrillation (persAF) remains challenging due to the absence of a ‘ground truth’ for atrial substrate characterization and the presence of multiple mechanisms driving the arrhythmia. We implemented an unsupervised classification to identify clusters of atrial electrograms (AEGs) with similar patterns, which were then validated by AEG-derived markers. Methods: 956 bipolar AEGs were collected from 11 persAF patients. CARTO variables (Biosense Webster; ICL, ACI and SCI) were used to create a 3D space, and subsequently used to perform an unsupervised classification with k-means. The characteristics of the identified groups were investigated using nine AEG-derived markers: sample entropy (SampEn), dominant frequency, organization index (OI), determinism, laminarity, recurrence rate (RR), peak-to-peak (PP) amplitude, cycle length (CL), and wave similarity (WS). Results: Five AEG classes with distinct characteristics were identified (F = 582, P<0.0001). The presence of fractionation increased from class 1 to 5, as reflected by the nine markers. Class 1 (25%) included organized AEGs with high WS, determinism, laminarity, and RR, and low SampEn. Class 5 (20%) comprised fractionated AEGs with in low WS, OI, determinism, laminarity, and RR, and in high SampEn. Classes 2 (12%), 3 (13%) and 4 (30%) suggested different degrees of AEG organization. Conclusions: Our results expand and reinterpret the criteria used for automated AEG classification. The nine markers highlighted electrophysiological differences among the five classes found by the k-means, which could provide a more complete characterization of persAF substrate during ablation target identification in future clinical studies. [ABSTRACT FROM AUTHOR]

Purpose: Identifying targets for catheter ablation remains challenging in persistent atrial fibrillation (persAF). The dominant frequency (DF) of atrial electrograms during atrial fibrillation (AF) is believed to primarily reflect local activation. Highest DF (HDF) might be responsible for the initiation and perpetuation of persAF. However, the spatiotemporal behavior of DF remains not fully understood. Some DFs during persAF were shown to lack spatiotemporal stability, while others exhibit recurrent behavior. We sought to develop a tool to automatically detect recurrent DF patterns in persAF patients. Methods: Non-contact mapping of the left atrium (LA) was performed in 10 patients undergoing persAF HDF ablation. 2,048 virtual electrograms (vEGMs, EnSite Array, Abbott Laboratories, USA) were collected for up to 5 min before and after ablation. Frequency spectrum was estimated using fast Fourier transform and DF was identified as the peak between 4 and 10 Hz and organization index (OI) was calculated. The HDF maps were identified per 4-s window and an automated pattern recognition algorithm was used to find recurring HDF spatial patterns. Dominant patterns (DPs) were defined as the HDF pattern with the highest recurrence. Results: DPs were found in all patients. Patients in atrial flutter after ablation had a single DP over the recorded time period. The time interval (median [IQR]) of DP recurrence for the patients in AF after ablation (7 patients) decreased from 21.1 s [11.8 49.7 s] to 15.7 s [6.5 18.2 s]. The DF inside the DPs presented lower temporal standard deviation (0.18 ± 0.06 Hz vs. 0.29 ± 0.12 Hz, p < 0.05) and higher OI (0.35 ± 0.03 vs. 0.31 ± 0.04, p < 0.05). The atrial regions with the highest proportion of HDF region were the septum and the left upper pulmonary vein. Conclusion: Multiple recurrent spatiotemporal HDF patterns exist during persAF. The proposed method can identify and quantify the spatiotemporal repetition of the HDFs, where the high recurrences of DP may suggest a more organized rhythm. DPs presented a more consistent DF and higher organization compared with non-DPs, suggesting that DF with higher OI might be more likely to recur. Recurring patterns offer a more comprehensive dynamic insight of persAF behavior, and ablation targeting such regions may be beneficial. [ABSTRACT FROM AUTHOR]

The unstable temporal behavior of atrial electrical activity during persistent atrial fibrillation (persAF) might influence ablation target identification, which could explain the conflicting persAF ablation outcomes in previous studies. We sought to investigate the temporal behavior and consistency of atrial electrogram (AEG) fractionation using different segment lengths. Seven hundred ninety-seven bipolar AEGs were collected with three segment lengths (2.5, 5,and 8 s) from 18 patients undergoing persAF ablation. The AEGs with 8-s duration were divided into three 2.5-s consecutive segments. AEG fractionation classification was applied off-line to all cases following the CARTO criteria; 43% of the AEGs remained fractionated for the three consecutive AEG segments, while nearly 30% were temporally unstable. AEG classification within the consecutive segments had moderate correlation (segment 1 vs 2: Spearman's correlation ρ = 0.74, kappa score κ = 0.62; segment 1 vs 3: ρ = 0.726, κ = 0.62; segment 2 vs 3: ρ = 0.75, κ = 0.68). AEG classifications were more similar between AEGs with 5 and 8 s (ρ = 0.96, κ = 0.87) than 2.5 versus 5 s (ρ = 0.93, κ = 0.84) and 2.5 versus 8 s (ρ = 0.90, κ = 0.78). Our results show that the CARTO criteria should be revisited and consider recording duration longer than 2.5 s for consistent ablation target identification in persAF. [ABSTRACT FROM AUTHOR]

Background Silent cerebral lesions (SCLs) are a potential complication of left atrial radiofrequency ablation (RFA) procedures for paroxysmal atrial fibrillation (PAF). We aimed to compare the incidence of SCLs in patients treated with irrigated RFA multielectrode catheters (nMARQ® Catheter group) and irrigated focal RFA catheters (NAVISTAR® THERMOCOOL® Catheter; TC group) after PAF ablation from subpopulation neurological assessment (SNA) cohorts of the REVOLUTION and reMARQable studies. Methods Data from SNA cohorts in the prospective, nonrandomized REVOLUTION study (March 2011-September 2013) and the prospective, randomized, controlled reMARQable study (October 2013-November 2015) were included. The incidence of SCLs was assessed pre- and postablation using magnetic resonance imaging. Neurological deficits were assessed using the National Institutes of Health Stroke Scale, modified Rankin Scale, and Montreal Cognitive Assessment. Results A total of 37 patients from REVOLUTION and 76 patients from reMARQable were included in the SNA cohort of each study. In the REVOLUTION SNA cohort, the incidence of SCLs was 21.1% (4/19) in the nMARQ® Catheter group and 5.9% (1/17) in the TC group. Findings from REVOLUTION helped inform the reMARQable study protocol's stringent anticoagulation regimen. SCL incidence was subsequently reduced in both groups (nMARQ® Catheter, 7.9%; TC, 3.3%). No permanent neurological deficits were observed. Conclusion Adherence to a stringent anticoagulation regimen prior to and during ablation procedures appears to be an important factor in minimizing the risk of SCL. [ABSTRACT FROM AUTHOR]

Purpose: Complex fractionated atrial electrograms (CFAE)-guided ablation after pulmonary vein isolation (PVI) has been used for persistent atrial fibrillation (persAF) therapy. This strategy has shown suboptimal outcomes due to, among other factors, undetected changes in the atrial tissue following PVI. In the present work, we investigate CFAE distribution before and after PVI in patients with persAF using a multivariate statistical model. Methods: 207 pairs of atrial electrograms (AEGs) were collected before and after PVI respectively, fromcorresponding LA regions in 18 persAF patients. Twelve attributes were measured from the AEGs, before and after PVI. Statistical models based on multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA) have been used to characterize the atrial regions and AEGs. Results: PVI significantly reduced CFAEs in the LA (70 vs. 40%; P < 0.0001). Four types of LA regions were identified, based on the AEGs characteristics: (i) fractionated before PVI that remained fractionated after PVI (31%of the collected points); (ii) fractionated that converted to normal (39%); (iii) normal prior to PVI that became fractionated (9%) and; (iv) normal that remained normal (21%). Individually, the attributes failed to distinguish these LA regions, but multivariate statistical models were effective in their discrimination (P < 0.0001). Conclusion: Our results have unveiled that there are LA regions resistant to PVI, while others are affected by it. Although, traditional methods were unable to identify these different regions, the proposed multivariate statistical model discriminated LA regions resistant to PVI from those affected by it without prior ablation information. [ABSTRACT FROM AUTHOR]

nMARQ AF Ablation Background nMARQ is a multipolar catheter designed to simultaneously ablate at multiple sites around the pulmonary vein (PV) circumference with a single radiofrequency application. We sought to define the safety and efficacy of atrial fibrillation (AF) ablation with the nMARQ catheter. Methods In a multicenter study, patients with drug-refractory AF were included. Procedural outcomes were documented at 1 year. Results 374 patients underwent PV isolation using nMARQ (age 60 ± 10 years, 264 male), of whom 263 patients had paroxysmal AF (PAF), while 111 patients had persistent AF. A total of 1,468 of 1,474 veins (99.6%) were isolated with the nMARQ catheter alone. Thirty-five (13%) PAF patients and 30 (27%) persistent AF patients underwent additional ablation at non-PV sites (2.4 ± 1.4 non-PV sites). Procedure time for PV isolation only was 1.9 ± 0.7 hours (fluoroscopy 24 ± 14 minutes). Procedure time for PV isolation and non-PV ablation was 2.4 ± 1.0 hours (fluoroscopy 30 ± 23 minutes). Major adverse events occurred in two patients (0.5%); one esophago-pericardial fistula and a second, mortality due to sepsis of unknown cause. One-year follow-up data were available in 65 (25%) PAF and 20 (18%) persistent AF patients. Forty-two (65%) PAF and 13 (65%) persistent AF patients were free of arrhythmia at 1 year. In patients undergoing repeat procedures (n = 17) the most frequent points of PV reconnection were: anterior RSPV, inferior RIPV, and superior LSPV. Conclusions AF ablation with nMARQ is associated with short procedure times and high acute success rates. Further research is necessary to more clearly define long-term outcome. [ABSTRACT FROM AUTHOR]

Frequency Trajectory of Atrial Fibrillation Introduction The role of substrates in the maintenance of persistent atrial fibrillation (persAF) remains poorly understood. The use of dominant frequency (DF) mapping to guide catheter ablation has been proposed as a potential strategy, but the characteristics of high DF sites have not been extensively studied. This study aimed to assess the DF spatiotemporal stability using high density noncontact mapping (NCM) in persAF. Methods and Results Eight persAF patients were studied using NCM during AF. Ventricular far-field cancellation was performed followed by the calculation of DF using Fast Fourier Transform. Analysis of DF stability and spatiotemporal behavior were investigated including characteristics of the highest DF areas (HDFAs). A total of 16,384 virtual electrograms (VEGMs) and 232 sequential high density 3-dimensional DF maps were analyzed. The percentage of DF stable points decreased rapidly over time. Repetition or reappearance of DF values were noted in some instances, occurring within 10 seconds in most cases. Tracking the HDFAs' center of gravity revealed 3 types of propagation behavior, namely (i) local, (ii) cyclical, and (iii) chaotic activity, with the former 2 patterns accounting for most of the observed events. Conclusions DF of individual VEGMs was temporally unstable, although reappearance of DF values occurred at times. Hence, targeting sites of 'peak DF' from a single time frame is unlikely to be a reliable ablation strategy. There appears to be a predominance of local and cyclical activity of HDFAs hinting a potentially nonrandom temporally periodic behavior that provides further mechanistic insights into the maintenance of persAF. [ABSTRACT FROM AUTHOR]

The Impact of Power Output During Percutaneous Catheter Radiofrequency Ablation Introduction Percutaneous catheter radiofrequency ablation (RFA) has been widely used to treat patients with atrial fibrillation (AF). Success rates are, however, variable and optimal levels of power used and duration of power delivery have not been fully established. Different ablation centers continue to use various power protocols. We undertook a comprehensive systematic review to evaluate the impact of power output during RFA for AF on efficacy and safety. Methods and results We systematically searched MEDLINE and Cochrane Central Register of Controlled Trials databases for studies on power output during percutaneous RFA for AF. The marked heterogeneous nature of the studies prohibited a meta-analysis. The main findings were (1) power output of ≤30 watts (W) has good safety profiles but low efficacy rates; (2) power output of >30 W-<45 W is safe with good efficacy; (3) power output of ≥ 45 W has a better efficacy profile but associated with a high risk of complications; (4) delivery of higher power of ≥ 45 W at shorter duration (15-20 seconds) is safe and efficacious; and (5) energy titration with visualization of microbubbles by intracardiac echocardiography (ICE) has better efficacy and safety profiles compared to RFA without ICE. Conclusions Despite the overall reduced quality data relating power to outcomes of RFA for AF, the optimal power output showing good efficacy and safety profiles appears generically to be >30 W-<45 W, with significant variation in the literature. [ABSTRACT FROM AUTHOR]

The article discusses guidelines for treating patients with ventricular ectopic beats (VEB). There is no clear evidence that caffeine restriction is effective in reducing VEB frequency. Catheter ablation is effective in treating patients with VEB arising from the right ventricular outflow tract. Beta blockers may be used to control symptom in patients where VEB arise from multiple sites.

The article presents a case study of a 68-year-old woman who was referred for first-time ablation of symptomatic paroxysmal atrial fibrillation (AF).Topics discussed include selection of a single catheter approach to mapping and ablation, disclosure of a left-sided superior vena cava (LSVC) draining into a markedly dilated coronary sinus (CS) and deployment of nMARQ Catheter System in the LSVC for targeting markedly fractionated signals in bipolar and unipolar energy delivery configurations.

ABSTRACT Background Methods Results Conclusion Pulmonary vein isolation (PVI) has been established as an effective management option for symptomatic paroxysmal atrial fibrillation (PAF). We aimed to explore the role of P‐wave parameters in a 12‐lead electrocardiogram (ECG) in predicting the success of repeat PAF ablation.We enrolled consecutive patients who underwent a second AF ablation procedure for PAF in a UK tertiary center after an index ablation conducted between 2018 and 2019 and a repeat ablation up to 2021. A digital 12‐lead ECG was recorded with a 1–50‐Hz bandpass filter applied. P‐wave duration (PWD), P‐wave voltage (PWV), P‐wave dispersion (PWDisp), and P‐wave terminal force in V1 (PTFV1) were measured before and after the procedure. Changes were correlated with the 12‐month clinical outcome. Procedural success was freedom from ECG‐documented AF up to 12 months following ablation.Study criteria were satisfied by 72 patients, of which 43 (60%) had successful repeat PVI at 12 months. The mean age is 65, and 47 (65%) were males. The demographics were comparable between both study arms. PWD decreased after successful repeat ablations (136.7 to 124.6 ms, p = 0.01) and failed repeat ablations (135.4 to 125.3 ms, p = 0.009) without a significant change between both arms. PMV and PWDisp did not change significantly after both study arms. PTFV1 significantly decreased after successful repeat ablations (‐3.1 to ‐4.4 mm.s, p = 0.005) without a significant change after failed ablations (‐2.9 to ‐2.7 mm.s, p = 0.42). Changes were statistically significant between both arms (p = 0.004).PTFV1 reduction following the second AF ablation was correlated with successful repeat AF ablation at 12 months. [ABSTRACT FROM AUTHOR]

Background and Objective Optimal targets for persistent atrial fibrillation (persAF) ablation are still debated. Atrial regions hosting high dominant frequency (HDF) are believed to participate in the initiation and maintenance of persAF and hence are potential targets for ablation, while rotor ablation has shown promising initial results. Currently, no commercially available system offers the capability to automatically identify both these phenomena. This paper describes an integrated 3D software platform combining the mapping of both frequency spectrum and phase from atrial electrograms (AEGs) to help guide persAF ablation in clinical cardiac electrophysiological studies. Methods 30 s of 2048 non-contact AEGs (EnSite Array, St. Jude Medical) were collected and analyzed per patient. After QRST removal, the AEGs were divided into 4 s windows with a 50% overlap. Fast Fourier transform was used for DF identification. HDF areas were identified as the maximum DF to 0.25 Hz below that, and their centers of gravity (CGs) were used to track their spatiotemporal movement. Spectral organization measurements were estimated. Hilbert transform was used to calculate instantaneous phase. Results The system was successfully used to guide catheter ablation for 10 persAF patients. The mean processing time was 10.4 ± 1.5 min, which is adequate comparing to the normal electrophysiological (EP) procedure time (120∼180 min). Conclusions A customized software platform capable of measuring different forms of spatiotemporal AEG analysis was implemented and used in clinical environment to guide persAF ablation. The modular nature of the platform will help electrophysiological studies in understanding of the underlying AF mechanisms. [ABSTRACT FROM AUTHOR]

Background We evaluated the use of a novel High Density Mesh Ablator (HDMA) catheter in combination with three-dimensional navigation for the treatment of paroxysmal atrial fibrillation. Methods The HDMA catheter was used to carry out pulmonary vein isolation in a consecutive series of patients. Three-dimensional geometry of the left atrial-pulmonary vein (LA-PV) junctions were first created with the HDMA catheter. Ostial, proximal and distal sites within the pulmonary veins were tagged with catheter shadows on the created geometry to allow for re-interrogation of these exact sites after ablation. Results The HDMA catheter was successfully used to create three dimensional geometry of the LA-PV junction in a total of 20 pulmonary veins which involved 5 patients. In all cases, ostial ablation alone was sufficient to achieve electrical isolation. No significant pulmonary vein stenosis was seen acutely after ablation. Conclusion We describe the successful use of the novel HDMA catheter to create three-dimensional geometry of the LA-PV junction to assist with pulmonary vein isolation. [ABSTRACT FROM AUTHOR]