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Success rates for catheter ablation of atrial fibrillation (AF), particularly persistent AF, remain suboptimal. Pulmonary vein isolation has been the cornerstone for catheter ablation of AF for over a decade. While successful for most patients, pulmonary vein isolation alone is still insufficient for a substantial minority. Frustratingly, multiple clinical trials testing a diverse array of additional ablation approaches have led to mixed results, with no current strategy that improves AF outcomes beyond pulmonary vein isolation in all patients. Nevertheless, this large collection of data could be used to extract important insights regarding AF mechanisms and the diversity of the AF syndrome. Mechanistically, the general model for arrhythmogenesis prompts the need for tools to individually assess triggers, drivers, and substrates in individual patients. A key goal is to identify those who will not respond to pulmonary vein isolation, with novel approaches to phenotyping that may include mapping to identify alternative drivers or critical substrates. This, in turn, can allow for the implementation of phenotype-based, targeted approaches that may categorize patients into groups who would or would not be likely to respond to catheter ablation, pharmacological therapy, and risk factor modification programs. One major goal is to predict individuals in whom additional empirical ablation, while feasible, may be futile or lead to atrial scarring or proarrhythmia. This work attempts to integrate key lessons from successful and failed trials of catheter ablation, as well as models of AF, to suggest future paradigms for AF treatment., Competing Interests: Dr Goldberger is a co-inventor on a patent for electrogram morphology recurrence analysis. Dr Narayan is a co-inventor on intellectual property owned by University of California regents and Stanford University on atrial fibrillation mapping.

Introduction: Multiple analysis techniques evaluate electrograms during atrial fibrillation (AF), but none have been established to guide catheter ablation. This study compares electrogram properties recorded from multiple right (RA) and left atrial (LA) sites., Methods: Multisite LA/RA mapping (281 ± 176/239 ± 166 sites/patient) was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (n = 32) or redo-AF ablation (n = 10). All electrogram recordings were visually reviewed and artifactual signals were excluded leaving a total of 21 846 for analysis. Electrogram characteristics evaluated were cycle length (CL), amplitude, Shannon's entropy (ShEn), fractionation interval, dominant frequency, organizational index, and cycle length of most recurrent morphology (CL R ) from morphology recurrence plot analysis., Results: Electrogram characteristics were correlated to each other. All pairwise comparisons were significant (p < .001) except for dominant frequency and CL R (p = .59), and amplitude and dominant frequency (p = .38). Only ShEn and fractionation interval demonstrated a strong negative correlation (r = -.94). All other pairwise comparisons were poor to moderately correlated. The relationships are highly conserved among patients, in the RA versus LA, and in those undergoing initial versus redo ablations. Antiarrhythmic drug therapy did not have a significant effect on electrogram characteristics, except minimum ShEn. Electrogram characteristics associated with ablation outcome were shorter minimum CL R , lower minimum ShEn, and longer mimimum CL. There was minimal overlap between the top 10 sites identified by one electrogram characteristic and the top 10 sites identified by the other 10 characteristics., Conclusion: Multiple techniques can be employed for electrogram analysis in AF. In this analysis of eight different electrogram characteristics, seven were poorly to moderately correlated and do not identify similar locations. Only some characteristics were predictive of ablation outcome. Further studies to consider electrogram properties, perhaps in combination, for categorizing and/or mapping AF are warranted., (© 2023 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background: There are no standard mapping approaches for patients with persistent atrial fibrillation (PeAF), particularly after failed prior catheter ablation (CA). In this study, we assess the feasibility of using Electrogram Morphology Recurrence (EMR) to guide ablation., Methods: Ten patients with recurrent PeAF after prior CA underwent detailed mapping of both atria during PeAF using the PentaRay (4 mm interelectrode spacing) and 3D mapping with CARTO. At each site, 15 s recordings were made. Custom software identified each electrogram and cross-correlation was used to identify the most recurrent electrogram morphology from which the % recurrence and cycle length of the most repeatable morphology (CL R ) was calculated. Sites of shortest CL R and sites within 5 ms of shortest CL R with recurrence ≥ 80% were used to inform CA strategy., Results: A mean of 342.9 ± 131.9 LA and 328.6 ± 91.5 RA sites were recorded per patient. Nine had PV reconnection. Shortest CL R sites guided ablation in 6/10 patients while 1 patient failed to fulfill shortest CL R criteria, and another 3 did not undergo CA guided by shortest CL R due to operator preference. On 12-month follow-up, all 4 patients without shortest CL R guided CA had recurrent PeAF. Of the 6 patients with shortest CL R guided CA, 5 patients did not have recurrent PeAF (p = 0.048), although 1 had paroxysmal AF and 2 had atypical atrial flutter., Conclusion: EMR is a feasible, novel technique to guide CA in patients with PeAF. Further evaluation is needed to provide an electrogram-based method for mapping guided targeted ablation of key areas., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Electrogram (EGM) morphology recurrence (EMR) mapping of persistent atrial fibrillation (AF) quantifies consistency of activation and is expected to be high and rapid near AF drivers., Objectives: The purpose of this study was to compare EMR in left atria (LA) and right atria (RA) in patients undergoing first vs redo ablation for persistent AF., Methods: Multisite LA/RA mapping (LA: 281 ± 176 sites/patient; RA: 239 ± 166 sites/patient) before persistent AF ablation was performed in 42 patients (30 males, age 63 ± 9 years) undergoing first (Group 1, n = 32) or redo ablation (Group 2, n = 10). After cross-correlation of each automatically detected EGM with every other EGM per recording, the most recurrent electrogram morphology was identified and its frequency (Rec%) and recurrence cycle length (CL R ) were computed., Results: In Groups 1 and 2, minimum CL R was 172.8 ± 26.0 milliseconds (LA: 178.2 ± 37.6 milliseconds, RA: 204.4 ± 34.0 milliseconds, P = 0.0005) and 186.5 ± 28.3 milliseconds (LA: 196.1 ± 38.1 milliseconds vs RA: 199.0 ± 30.2 milliseconds, P = 0.75), with Rec% 94.7% ± 10% and 93.8% ± 9.2%. Group 2 minimum CL R was not different from Group 1 (P = 0.20). Shortest CL R was in the LA in 84% of Group 1 and 50% of Group 2 patients (P = 0.04). Only 1 of 10 patients in Group 2 had the shortest CL R in the pulmonary veins (PVs) compared with 19 of 32 in Group 1 (P = 0.01). Most sites (77.6%) had Rec% <50%., Conclusions: EMR identified the shortest CL R sites in the PVs in 59% of patients undergoing initial persistent AF ablation, consistent with reported success rates of ∼50% for PV isolation. The majority of sites have low recurrence and may reflect bystander sites not critical for maintaining AF. EMR provides a robust new method for quantifying consistency and rapidity of activation direction at multiple atrial sites., Competing Interests: Funding Support and Author Disclosures This study was funded by grants 1R01HL125881 and 1R41HL127907 from the National Heart, Lung, and Blood Institute, National Institutes of Health. Drs Mitrani and Goldberger have received funding from the Miami Heart Research Institute. Drs Jason Ng and Goldberger are inventors in a patent application for EMR analysis. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023. Published by Elsevier Inc.)

Background: Ablation approaches have been described for the management of symptomatic ventricular arrhythmias in patients with Brugada syndrome, but this treatment is still considered experimental., Objective: We aimed to perform a systematic review of the current evidence on the use of catheter ablation in Brugada syndrome., Methods: MEDLINE, Embase, and Scopus were searched for articles describing the use of catheter ablation for ventricular arrhythmia management in Brugada syndrome., Results: We included 11 case series and 11 case reports including a total of 233 patients. Ablation strategies included epicardial mapping with substrate modification (n = 180; 77.3%), endocardial-only mapping with substrate modification (n = 17; 7.3%), ventricular fibrillation (VF)-triggering premature ventricular complex ablation (n = 5; 2.1%), and mixed approaches (n = 31; 13.3%). During a 2.5- to 78-month follow-up period, the success rates in preventing ventricular tachycardia or VF (VT/VF) were 96.7%, 70.6%, and 80% with epicardial, endocardial, and triggering premature ventricular complex ablation approaches, respectively. Among patients who underwent both epicardial and endocardial mapping, there was no identifiable endocardial substrate in 92.9% of cases. Elimination of type 1 Brugada-pattern electrocardiogram was attained in 98.3% and 34.8% of the epicardial and endocardial ablation groups, respectively. VT/VF occurred in 7 of 9 patients (77.8%) who had persistent or recurrent J-ST elevation and in none of the 24 patients with complete resolution during follow-up. Pharmacologic provocation augmented the abnormal area., Conclusion: Epicardial substrate modification appears to be more effective than endocardial-only approach in preventing VT/VF. Persistent or recurrent J-ST elevation appears to represent a marker of failure of ablation. Ablation seems to be an acceptable strategy for patients with Brugada syndrome and VT/VF., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Radiofrequency (RF) and cryoballoon (CB) catheter ablation are effective for pulmonary vein isolation (PVI) in atrial fibrillation (AF). This report presents an updated meta-analysis comparing the efficacy and safety of CB versus RF ablations in AF., Methods: Databases and conference abstracts were systematically searched for studies that directly compared CB and RF PVI, and reported safety or efficacy outcomes in follow-up ≥12 months. Recurrent atrial tachyarrhythmias (AT) were defined as AF, atrial flutter, or atrial tachycardia., Results: Twenty-two studies and 8,668 patients were included. Freedom from AT was not significantly different between CB and RF ablations in the pooled population (OR 1.12; 95%CI 0.97-1.29; P = 0.13) and in randomized trials (OR 1.0; 95%CI 0.65-1.56; P = 0.99). Second-generation CB (CB2; 78.1%) and contact-force (CF) sensing RF (78.2%) have improved procedure success rate as compared to first-generation technology (57.9% CB, 58.1% RF). As compared to CF-RF, CB2 demonstrated similar freedom from recurrent AT (OR 1.04; 95%CI 0.71-1.51; P = 0.84). The incidence of pericardial effusions (OR 0.44; 95%CI 0.28-0.69; P < 0.01), tamponade (OR 0.31; 95%CI 0.15-0.64; P < 0.01), and non-AF AT (OR 0.46; 95%CI 0.26-0.83; P < 0.01) were significantly lower with CB ablation, whereas transient phrenic nerve palsy was more incident after CB (OR 7.40; 95%CI 2.56-21.34; P < 0.01)., Conclusion: There was comparable freedom from AT between CB and RF in patients with AF undergoing PVI. Additionally, freedom from AT was similar between CB2 and CF-RF. However, CB was associated with a lower incidence of pericardial effusions or tamponade, albeit with a higher rate of transient phrenic nerve palsies., (© 2016 Wiley Periodicals, Inc.)

Catheter ablation for atrial fibrillation (AF) has emerged as a popular procedure. The purpose of this study was to examine whether there exist differences or disparities in ablation utilization across gender, socioeconomic class, insurance, or race. Using the Nationwide Inpatient Sample (2000 to 2012), we identified adults hospitalized with a principal diagnosis of AF by ICD 9 code 427.31 who had catheter ablation (ICD 9 code-37.34). We stratified patients by race, insurance status, age, gender, and hospital characteristics. A hierarchical multivariate mixed-effect model was created to identify the independent predictors of AF ablation. Among an estimated total of 3,508,122 patients (extrapolated from 20% Nationwide Inpatient Sample) hospitalized with a diagnosis of AF in the United States from the year 2000 to 2012, 102,469 patients (2.9%) underwent catheter ablations. The number of ablations was increased by 940%, from 1,439 in 2000 to 15,090 in 2012. There were significant differences according to gender, race, and health insurance status, which persisted even after adjustment for other risk factors. Female gender (0.83 [95% CI 0.79 to 0.87; p <0.001]), black (0.49 [95% CI 0.44 to 0.55; p <0.001]), and Hispanic race (0.64 [95% CI 0.56 to 0.72; p <0.001]) were associated with lower likelihoods of undergoing an AF ablation. Medicare (0.93, 0.88 to 0.98, <0.001) or Medicaid (0.67, 0.59 to 0.76, <0.001) coverage and uninsured patients (0.55, 0.49 to 0.62, <0.001) also had lower rates of AF ablation compared to patients with private insurance. In conclusion we found differences in utilization of catheter ablation for AF based on gender, race, and insurance status that persisted over time., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation ablation has made tremendous progress with respect to innovation, efficacy, and safety. However, limited data exist regarding the burden and trends in adverse outcomes arising from this procedure. The aim of our study was to examine the frequency of adverse events attributable to atrial fibrillation (AF) ablation and the influence of operator and hospital volume on outcomes., Methods and Results: With the use of the Nationwide Inpatient Sample, we identified AF patients treated with catheter ablation. We investigated common complications including cardiac perforation and tamponade, pneumothorax, stroke, transient ischemic attack, vascular access complications (hemorrhage/hematoma, vascular complications requiring surgical repair, and accidental arterial puncture), and in-hospital death described with AF ablation, and we defined these complications by using validated International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes. An estimated 93,801 AF ablations were performed from 2000 to 2010. The overall frequency of complications was 6.29% with combined cardiac complications (2.54%) being the most frequent. Cardiac complications were followed by vascular complications (1.53%), respiratory complications (1.3%), and neurological complications (1.02%). The in-hospital mortality was 0.46%. Annual operator (<25 procedures) and hospital volume (<50 procedures) were significantly associated with adverse outcomes. There was a small (nonsignificant) rise in overall complication rates., Conclusions: The overall complication rate was 6.29% in patients undergoing AF ablation. There was a significant association between operator and hospital volume and adverse outcomes. This suggests a need for future research into identifying the safety measures in AF ablations and instituting appropriate interventions to improve overall AF ablation outcomes.