Procedural Atrial Fibrillation Termination Research Articles

PO-02-160 NOVEL APPLICATION OF THE WAVE DYNAMICS USING HIGH DENSITY VECTOR FIELD MAPPING FOR PERSISTENT ATRIAL FIBRILLATION

Catheter ablation for persistent atrial fibrillation (AF) has shown limited success. The vector field (VF) mapping illustrates the stationary waveform propagating during AF, can compute the global propagation patterns to demonstrate the mechanism of AF maintenance. This study aimed to visualize the global wavefront pattern during AF by using VF mapping and investigate the ablation outcome based on different pattern. In phase 1 study, we applied a cellular automation technique to simulate the electrical wave propagation to improve the VF mapping algorithm, involving analysis of high similarity electrogram vectors to to display the stable wave propagation of AF. In the phase 2 study, patients with persistent AF underwent catheter ablation were prospectively enrolled. (Group 1 [N=35]: AF drivers emanating from 1 or more PVs; Group 2 [N=30]: No AF drivers emanating from 1 or more PVs). VF mapping and PRISM-guided PVI was performed in all patients. The patient characteristics and procedural data were extracted for analysis. We evaluated the single-procedure freedom from AF after first ablation procedure. We identified an average of 2.7±2.0 VF regions per patients. These regions (N=177) involved PV (N=100) and left atrium (N=77). A higher procedural AF termination rate (43%vs. 17%, P=0.03) was achieved in Gp-1 than Gp-2. Gp-1 patients had a significant reduction in all arrhythmia recurrence compared to Gp-2. After multivariate analysis, the behavior of driver emanating from PV (Hazards ratio [HR] 0.426, 95% confidence interval [CI]: 0.187-0.968, P =0.042) and the left atrial diameter (HR 1.092, 95% CI: 1.021-1.169, P = 0.011) independently predicted the recurrence. VF mapping of persistent AF revealed the waveform dynamic of the entire atrial chamber and revealed the spatially stable AF drivers with sink-to-source phenomenon to the rest of the atrium. The arrhythmogenic drivers within PVs/antra are predictive of the successful PV isolation in patients with persistent AF.

Ablation guided by STAR-mapping in addition to pulmonary vein isolation is superior to pulmonary vein isolation alone or in combination with CFAE/linear ablation for persistent AF.

IntroductionThe optimal ablation approach for persistent atrial fibrillation (AF) remains unclear.Methods and ResultsObjective was to compare the long‐term rates of freedom from AF/AT in patients that underwent STAR mapping guided ablation against outcomes of patients undergoing conventional ablation procedures.Patients undergoing ablation for persistent AF as part of the Stochastic Trajectory Analysis of Ranked signals (STAR) mapping study were included. Outcomes following 'pulmonary vein isolation (PVI) plus STAR mapping guided ablation (STAR mapping cohort) were compared to patients undergoing PVI alone ablation during the same time period and also a propensity‐matched cohort undergoing PVI plus the addition of complex fractionated electrogram (CFAE) and/or linear ablation (“conventional ablation”). Rates of procedural AF termination and freedom from AF/AT during follow‐up were compared.Sixty‐five patients were included in both the STAR cohort and propensity matched conventional ablation cohort. AF termination rates were significantly higher in the STAR cohort (51/65, 78.5%) than conventional ablation cohort (10/65, 15.4%) and PVI alone ablation cohort (13/50, 26.0%; STAR cohort vs. other 2 cohorts both p < .001). There was no significant difference in procedure time between the three cohorts. During ≥20 months follow‐up a lower proportion of patients had AF/AT recurrence in the STAR cohort (20.0%) compared with the conventional ablation cohort (50.8%) or the PVI alone ablation cohort (50.0%; both p < .05 compared to STAR cohort).ConclusionsOutcomes of PVI plus STAR mapping guided ablation was superior to PVI alone or in combination with linear/CFAE ablation. A multicenter randomized controlled trial is planned to confirm these findings.

Predictors of successful complex catheter ablation for persistent atrial fibrillation despite failure of targeted procedural arrhythmia termination.

Procedural atrial fibrillation (AF) termination is considered as a predictor of long-term success after catheter ablation for persistent AF (persAF). However, some patients remain free of arrhythmia recurrences despite failure to achieve AF termination. The objective of this study was to assess long-term outcome and prognostic factors in patients undergoing complex ablation without procedural AF termination. This study comprised 419 patients (63.8 ± 10.2 years, 63.4% male) undergoing complex ablation for persAF. Patients without procedural AF termination (n = 137, 64.2 ± 9.7 years, 63.5% male) were categorized into patients who remained in sinus rhythm (SR) in long-term outcome (SR-group) and patients with recurrence of AF or atrial tachycardia (AT) (AR-group). During a follow-up (FU) of 19.6 ± 14.6 months, the SR-group consisted of 65 (47.5%) and the AR-group of 69 (50.4%) patients. Three patients (2.2%) were lost to FU. Left atrial appendage (LAA) flow velocity and left atrium volume index (LAVI) could be identified as predictors for long-term success. LAA flow velocity and baseline AF cycle length (AFCL) were significantly associated with the type of arrhythmia recurrence (AF vs AT), ie, higher values of both are predictive for AT rather than AF recurrences. Patients with a LAVI < 34.4 mL/m² and significant AFCL increase during the ablation procedure had rather AT than AF recurrences. Patients with an arrhythmia-free outcome despite failure of procedural AF termination during complex ablation for persAF are characterized by specific morphological and functional properties that are easy to obtain.

Is ablation to termination the best strategy for ablation of persistent atrial fibrillation? Persistent atrial fibrillation is best ablated by a strategy that terminates the arrhythmia: procedural termination is associated with improved long-term outcomes.

Although effective results are attained with paroxysmal atrial fibrillation (AF) ablation based on pulmonary vein isolation (PVI), catheter ablation of persistent AF remains a challenging task. Current ablation approaches in persistent AF ablation are markedly diverse, and there is a considerable variation in the reported clinical outcomes.1 Moreover, the lack of a distinct procedural end point makes comparison between the studies difficult. Response by Latchamsetty and Oral on p 971 Recently, significant advances have been made with the development of novel technologies, such as computational mapping and panoramic noninvasive mapping to map drivers (rotors and focal discharges) during AF. The advent of these newer technologies and strategies for persistent AF ablation further raise the question as to whether AF termination should be the procedural end point, and whether it confers additional long-term clinical benefit. In this article, we review the current evidence on AF termination and long-term clinical outcome, procedural AF termination as a predictor of freedom from recurrent atrial arrhythmias, AF termination rates with various ablation strategies, and potential underlying mechanisms conferring clinical benefit and future directions. ### Search Strategy The English scientific literature in the PubMed database was searched using the terms catheter ablation, persistent AF, and termination in any region of the PubMed record until October 2014. Studies that described procedural AF termination rates during ablation together with clinical outcomes after ablation for patients with persistent AF or long-standing persistent AF were included. References from the relevant articles were reviewed to identify further related articles. Definition of AF termination included direct conversion to sinus rhythm (SR) and organization to atrial tachycardia (AT) during ablation. ### Studies Comparing Clinical Outcome in Patients With/Without AF Termination Of 20 identified studies directly comparing the clinical outcome of patients who achieved AF termination during ablation with those who did not terminate, the majority of studies (17 of 20) demonstrate significantly improved outcomes in …

Impact of Atrial Fibrillation Termination on Clinical Outcome after Ablation in Relation to the Duration of Persistent Atrial Fibrillation

Whether procedural termination of persistent atrial fibrillation (AF) is necessary for optimal clinical efficacy still remains controversial. We sought to characterize the patients with persistent AF in whom procedural AF termination impacted an improved clinical outcome after ablation. We retrospectively assessed 132 patients (61.0 ± 9.3 years, 114 males) undergoing catheter ablation of persistent AF (duration 3 years, median). A stepwise ablation approach including pulmonary vein isolation and atrial substrate ablation targeting complex fractionated and high-frequency electrograms was performed with desired endpoint of AF termination. Overall, 90 patients (68%) were free from recurrent arrhythmias at 20 ± 11 months of follow-up after one or two procedures. The left atrial diameter and continuous AF duration according to medical history were associated with the outcome (P = 0.002 and P< 0.001, respectively). In multivariate Cox regression analysis, the continuous AF duration was the only independent predictor of recurrent arrhythmias (hazard ratio 1.17, 95% confidence interval 1.10-1.23, P < 0.001). In patients with AF duration of ≥ 3 years, the clinical success was comparable regardless of whether AF termination was achieved or not (log-rank, P = 0.27). In the remaining patients with AF duration of <3 years, procedural AF termination was associated with a higher arrhythmia-free rate than when AF was sustained after ablation (log-rank, P = 0.023). Extensive ablation to terminate AF might not be warranted in patients with a longer AF duration. On the contrary, procedural AF termination could be associated with maintenance of sinus rhythm in patients with a shorter AF duration with a less proarrhythmic substrate. (PACE 2012;35:1436-1443).

Novel Assessment of Temporal Variation in Fractionated Electrograms Using Histogram Analysis of Local Fractionation Interval in Patients With Persistent Atrial Fibrillation

Background— The characteristics of atrial electrograms associated with atrial fibrillation (AF) termination are controversial. We investigated the electrogram characteristics that indicate procedural AF termination during continuous complex fractionated electrogram ablation. Methods and Results— Fifty-two consecutive patients with persistent AF (47 men; aged 54±9 years), who underwent electrogram-based catheter ablation in the left atrium and coronary sinus after pulmonary vein isolation, were enrolled. The intracardiac bipolar atrial electrogram recordings were characterized by (1) fractionation interval (FI) analysis (&gt;6 seconds), (2) kurtosis (shape of the FI histogram), and (3) skewness (asymmetry of the FI histogram). Sites showing complex, fractionated electrograms (mean FI ≤60 ms) were targeted, and AF was terminated in 20 patients (38%) after the pulmonary vein isolation. The conventional complex fractionated electrogram sites (mean ≤120 ms) in patients with AF termination exhibited higher median kurtosis (2.69 [interquartile range, 2.03–3.46] versus 2.35 [interquartile range, 1.79–2.48]; P =0.024) and higher complex fractionated electrogram-mean interval (102.7±19.8 versus 87.7±15.0; P =0.008) than patients without AF termination. Furthermore, AF termination sites had higher median kurtosis than targeted sites without AF termination (5.13 [interquartile range, 3.51–6.47] versus 4.18 [interquartile range, 2.91–5.34]; P &lt;0.01) in patients with procedural termination. In addition, patients with AF termination had a higher sinus rhythm maintenance rate after a single procedure than patients without AF termination (log-rank test, P =0.007). Conclusions— A kurtosis analysis using the FI histogram may be a useful tool in identifying the critical substrate for persistent AF and potential responders to catheter ablation.

Long-term single- and multiple-procedure outcome and predictors of success after catheter ablation for persistent atrial fibrillation

Stepwise ablation is an effective treatment for persistent atrial fibrillation (AF), although it often requires multiple procedures to eliminate recurrent arrhythmias. This study evaluated single- and multiple-procedure long-term success rates and potential predictors of a favorable single-procedure outcome of stepwise ablation for persistent AF. This study comprised 395 patients with persistent AF (duration 16 months) undergoing de novo catheter ablation using the stepwise approach. Procedural success was defined as the absence of any arrhythmia recurrence. Patient characteristics and electrophysiological parameters were analyzed with respect to single- and multiple-procedure outcomes. After a follow-up of 27 ± 7 months, 108 (27%) patients were free of arrhythmia recurrences with a single procedure. After 2.3 ± 0.6 procedures, 312 (79%) patients were free of arrhythmia with concomitant antiarrhythmic treatment in 38% (23% on β-blocker). Female gender, duration of persistent AF, and congestive heart failure were predictive for the outcome after first ablation. However, the strongest predictors for single-procedure success were longer baseline AF cycle length (CL) and procedural AF termination. Moreover, procedural AF termination during the index procedure also predicted a favorable outcome after the last procedure, while the existence of congestive heart failure was associated with an increased risk for eventual arrhythmia recurrences. Single-procedure long-term success is anticipated in approximately a quarter of patients undergoing de novo ablation of persistent AF. Baseline AFCL emerged as the strongest predictor of single-procedure success, while AF termination during index ablation predicts the overall outcome. However, an overall success rate of 79% is achievable with multiple procedures.

Relationship Between Arrhythmogenic Pulmonary Veins and the Surrounding Atrial Substrate in Patients with Paroxysmal Atrial Fibrillation

The relationship between pulmonary veins (PVs) with atrial fibrillation (AF) initiating triggers and their surrounding atrial substrate has not been elucidated. We aimed to clarify the atrial substrate properties around the PVs. Twenty-three paroxysmal AF patients were studied with the identification of PV initiating triggers. High-density mapping of the dominant frequency (DF, 1200 Hz) and the mean degree of the complex fractionated electrograms (CFE mean interval over 6 seconds) was evaluated in 2 zones (zone 1: < 5 mm, zone 2: 5-15 mm from the PVs) and the left atrial (LA) using a NavX system prior to the PV isolation. High-DFs (>8 Hz) and continuous CFEs (<50 ms) were identified in 1.5 ± 0.9 and 2.3 ± 1.1 regions per patient, respectively. Most of the high-DF regions (86%) and continuous CFE regions (77%) were located within 15 mm of the PV ostia. Of those, 75% of the high-DF regions and 54% of the continuous CFE regions were related to arrhythmogenic PVs. There was a significant DF gradient from arrhythmogenic PV zone 1 to zone 2, while the mean CFE exhibited a significant gradient between arrhythmogenic PV zone 2 and the rest of the LA. Additionally, 69% of the procedural AF termination sites were at arrhythmogenic PV zone 2. Evaluation of the atrial substrate properties may be useful for locating arrhythmogenic PVs during AF and defining the extent of the circumferential PV isolation.

Atrial defibrillation threshold as a novel predictor of clinical outcome of catheter ablation for persistent atrial fibrillation

Catheter ablation for persistent atrial fibrillation (AF) is currently performed with different procedural endpoints. When AF did not terminate during ablation procedure, electrical cardioversion was performed at different defibrillation threshold (DFT) according to AF characteristics and atrial electrophysiologic substrates. We sought to evaluate the impact of atrial DFT after catheter ablation for persistent AF on clinical outcome. We studied 128 patients with persistent AF (age 63±9 years, 106 men). After completion of circumferential pulmonary vein isolation, the left atrial substrate ablation was performed until AF terminated or all identified complex fractionated electrograms were eliminated. If AF did not terminate during ablation, an internal cardioversion protocol was started at 5J and was increased incrementally in 5 J steps until successful cardioversion was accomplished. Procedural AF termination was achieved in 50 patients (Group A). Atrial fibrillation was terminated by cardioversion with DFT≤10 J in 47 patients (Group B) and with DFT>10 J in 31 patients (Group C). At 14±7 follow-up months after 1.3±0.5 sessions, 47 (94%) Group A patients, 42 (89%) Group B patients, and 14 (45%) Group C patients remained in sinus rhythm. In multivariate analysis of Group B and Group C, DFT (hazard ratio 5.54, P<0.001) and AF duration (hazard ratio 3.74, P=0.011) were independent predictors of recurrent arrhythmia. When AF does not terminate after the completion of predetermined stepwise ablation, further extensive ablation to terminate AF might be unnecessary if the AF can be successfully terminated by electrical cardioversion at low DFT.

Efficacy of Additional Ablation of Complex Fractionated Atrial Electrograms for Catheter Ablation of Nonparoxysmal Atrial Fibrillation

The efficacy of ablation of complex fractionated atrial electrograms (CFEs) in the single ablation procedure for nonparoxysmal atrial fibrillation (AF) patients is not well demonstrated. The aim of this study was to compare the ablation strategies of pulmonary vein isolation (PVI) plus linear ablation with and without additional ablation ofCFEs in these patients. Consecutive 60 patients (49 +/- 11 years old, 50 male, 10 female) with nonparoxysmal AF underwent catheter ablation guided by a NavX mapping system. A stepwise approach included a circumferential PVI and left atrial (LA) linear ablation followed by either the additional ablation of continuous CFEs in the LA/coronary sinus (the first 30 patients) or not (the second 30 patients), detected by an automatic algorithm. There was no difference in the baseline characteristics between the two groups. Complete PVI eliminated some continuous CFEs and altered the distribution of CFEs. Following PVI and linear ablation,the remaining continuous CFEs were identified in 7.9 +/-10% mapping sites of the LA and CS, and were ablated successfully with a procedural AF termination rate of 53%. With a follow-up of 19 +/-11 months, a Kaplan-Meier analysis showed that the patients with additional ablation of the CFEs had a higher rate of sinus rhythm maintenance. Multivariate analysis showed the single procedure success could be predicted by the procedural AF termination and the additional ablation of continuous CFEs in the LA/CS. Ablation of continuous CFEs after PVI and LA linear ablation had a better long-term efficacy based on the results of single-ablation procedure.

Spatiotemporal Organization of the Left Atrial Substrate After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

There is a paucity of data regarding the mechanism of maintaining atrial fibrillation (AF) after pulmonary vein isolation (PVI) in patients with AF. The aim of this study was to examine the impact of circumferential PVI on the left atrial (LA) substrate characteristics. Seventy-two AF patients (age, 53+/-11 years) underwent mapping and catheter ablation using an NavX system. The biatrial characteristics such as the complex fractionated atrial electrograms (CFEs; based on fractionated intervals) and frequency analysis (based on dominant frequencies) were mapped before and after PVI. PVI with electric isolation was performed in all patients. In the 45 patients who did not respond to PVI, the continuous CFEs (>8 seconds, 18+/-18% and 12+/-17% of the LA sites, before and after PVI, respectively, P=0.02), degree of LA fractionation (mean fractionated interval: 75.6+/-14.3 msec versus 87.3+/-16.7 msec, P=0.001), and mean LA dominant frequencies (6.92+/-0.88 Hz versus 6.58+/-0.91 Hz, P=0.001) decreased after PVI. Complete PVI altered the distribution of the CFEs toward the LA anteroseptum, mitral annulus, and LA appendage regions. A persistent presence of continuous CFEs in the vicinity of the dominant frequencies sites (observed in 53% patients) correlated with a higher procedural AF termination rate for the CFE ablation (63% versus 23%, P<0.05). Complete PVI eliminated some CFEs in the LA and altered the distribution of the CFEs. The persistent presence of CFEs before and after PVI in the vicinity of the high frequency sites is important for AF maintenance after PVI.

High efficacy of the multifaceted strategy for persistent atrial fibrillation

Summary Catheter ablation of persistent atrial fibrillation (AF) is challenging and needs a combination of different techniques targeting a wider substrate to be effective. The so-called stepwise approach progressively targets structures potentially contributing to initiation and maintenance of AF. The endpoints of the procedure consist of pulmonary vein isolation, organisation and slowing of left and right atrial electrograms and linear block in the left atrial (LA) roof and mitral isthmus lines. This strategy results both in high rate of AF termination (85%) and an unprecedented clinical outcome. Electrogram-based ablation is crucial for the procedural outcome. While continuous and fractionated electrograms are targeted during complex atrial activity, more discrete sites like temporal activation gradient, rapid or centrifugal activity are ablated when atrial activity is organised allowing discrete mapping. AF cycle length (CL) measured in both appendages has been demonstrated to be the strongest independent predictor of procedural AF termination in AF lasting 140 ms predicts AF termination of more than 89%. AFCL also allows monitoring impact of each step of catheter ablation. LA ablation is usually associated with prolongation of both LA appendage (LAA) CL and right atrial appendage (RAA) CL, while prolongation of LAA CL without concomitant significant prolongation in RA suggests the presence of drivers in RA, requiring additional RA ablation. Because AF recurrence after the first procedure occurred in only 5% of the cases when AF terminated during the procedure vs 45% if AF persisted, AF termination represents an incontrovertible endpoint of the ablation process. The mode of termination of persistent AF is conversion to multiples atrial tachycardia (AT) in the vast majority of cases. Mapping and ablation of those have become indispensable steps in the ablation process. Predominant ATs are localised re-entries requiring mapping of local activity spanning most of the AT cycle length in the area of earliest activity. In conclusion, catheter ablation of persistent AF requires isolation of all PV electrogram based ablation and linear lesions in the majority of patients. AF CL is an important guide for monitoring progress of ablation and reliably predicts the procedural outcome. AF termination by ablation is associated with excellent outcome. Mapping and ablation of subsequent atrial tachycardias are an integral part of the AF ablation process and its success often makes the difference between cure and persistent illness.