Focal Impulse And Rotor Modulation Research Articles

Stand-alone Focal Impulse and Rotor Modulation (FIRM) ablation versus second-generation cryoballoon pulmonary vein isolation for paroxysmal atrial fibrillation.

Focal Impulse and Rotor Modulation (FIRM) guided catheter ablation aiming at stable rotors has been investigated as a treatment option in patients with atrial fibrillation (AF). The objective of this study was to compare the safety and efficacy of FIRM-guided ablation with second-generation cryoballoon pulmonary vein isolation (CB2-PVI) in paroxysmal AF. Consecutive patients (n = 22, mean age 60 ± 11 years, 59.1% of males) who were treated with a stand-alone FIRM-guided ablation were included in this retrospective single-center study. Procedural data and arrhythmia-free survival at 12 months were compared with n = 86 consecutive patients (mean age 62 ± 13 years, 62.4% of males) who received de-novo CB2-PVI. Median procedure duration was significantly longer in the FIRM group than in the CB2-PVI group (152 [IQR 120-176] minutes vs. 122 [110-145] minutes; p = .031). One patient (1.2%) in the CB2-PVI group and five patients (22.7%) in the FIRM group had vascular access complications. Atrial tachyarrhythmias recurred in 15 patients in the FIRM group and 11 in the CB2-PVI group. Kaplan-Meier estimation of single-procedure arrhythmia-free survival at 12 months was 25% (95% confidence interval [CI] 6%-44%) in the FIRM group and 87% (95% CI 78%-96%) in the CB2-PVI group (p < .001). Repeat ablations were performed in 14/20 (70.0%) patients in the FIRM group and in 12/85 (14.1%) in the CB2-PVI group (p < .001). De novo ablation of AF using FIRM-guided AF ablation results in shorter arrhythmia-free survival after 12 months compared to CB2-PVI and a need for repeat ablation in the majority of patients to achieve stable sinus rhythm.

B-PO04-093 FOCAL IMPULSE AND ROTOR MODULATION GUIDED ABLATION VERSUS PULMONARY VEIN ISOLATION FOR ATRIAL FIBRILLATION: A META-ANALYSIS OF HEAD-TO-HEAD COMPARATIVE STUDIES

Empirical pulmonary vein isolation (PVI) remains the cornerstone for catheter ablation of atrial fibrillation (AF). Various ablation strategies and modalities are continually tested with the aim of improving ablation outcomes. Although focal impulse and rotor modulation (FIRM)-guided ablation is currently used, evidence supporting this strategy is conflicting. We sought to examine whether the utilization of FIRM-guided ablation with or without PVI is associated with a decrease in all-atrial arrhythmia recurrence as compared to PVI alone. A systematic review of PubMed, Cochrane, and Embase was performed for head-to-head study designs comparing outcomes of patients who underwent FIRM-guided ablation with or without PVI to those who underwent PVI. The primary efficacy endpoint was all-atrial arrhythmia recurrence. The secondary endpoint was complication rates. Overall, six studies comprising 716 patients undergoing either FIRM-guided ablation +/- PVI vs PVI were included (mean age 63.4 ± 9.2, male 74%, 11.5% paroxysmal AF, 88.5% non-paroxysmal AF). After a mean follow-up of 18.8 months, FIRM-guided ablation with or without PVI was not associated with improvement in all-atrial arrhythmia recurrence rate compared to PVI alone (43.4% vs 45.9%, Risk Ratio [RR] 1.06, 95% Confidence Interval [CI] 0.77-1.47, P=0.70). No statistically significant difference was noted in complication rates between the two groups (RR 1.66, 95% CI 0.08-34.54, P=0.74). In this meta-analysis, FIRM-guided ablation with or without PVI did not provide any benefit in improving all-atrial arrhythmia recurrence when compared to PVI alone.

Focal impulse and rotor modulation guided ablation versus pulmonary vein isolation for atrial fibrillation: A meta-analysis of head-to-head comparative studies.

Empirical pulmonary vein isolation (PVI) remains the cornerstone for catheter ablation of atrial fibrillation (AF). Various ablation strategies and modalities are continually tested with the aim of improving ablation outcomes. Although focal impulse and rotor modulation (FIRM)-guided ablation is currently used as an adjunct to PVI, evidence supporting this strategy is conflicting. We sought to examine whether the utilization of FIRM-guided ablation with or without PVI is associated with a decrease in all-atrial arrhythmia recurrence as compared to PVI alone. A systematic review of PubMed, Cochrane, and Embase was performed for head-to-head study designs comparing outcomes of patients who underwent FIRM-guided ablation with or without PVI to those who underwent PVI alone. The primary efficacy endpoint was all-atrial arrhythmia recurrence. The secondary endpoints were complications rates and procedural characteristics. Overall, six studies comprising 674 patients undergoing either FIRM-guided ablation ± PVI versus PVI were included (mean age 63.4 ± 9.2, male 74%, 9% paroxysmal AF, 91% nonparoxysmal AF). After a mean follow-up of 18.8 months, FIRM-guided ablation with or without PVI was not associated with improvement in all-atrial arrhythmia recurrence rate compared to PVI alone (43.4% vs. 45.9%, risk ratio [RR]: 1.06; 95% confidence interval [CI]: 0.77-1.47; p = .70). No statistically significant difference was noted in complication rates between the two groups (RR: 1.66; 95% CI: 0.08-34.54; p = .74). In this meta-analysis of head-to-head comparison studies, FIRM-guided ablation with or without PVI did not provide any benefit in improving all-atrial arrhythmia recurrence at follow-up when compared to PVI alone.

Focal Impulse and Rotor Modulation Ablation vs. Pulmonary Vein isolation for the treatment of paroxysmal Atrial Fibrillation: results from the FIRMAP AF study.

AimsPulmonary vein isolation (PVI) is the gold standard for atrial fibrillation (AF) ablation. Recently, catheter ablation targeting rotors or focal sources has been developed for treatment of AF. This study sought to compare the safety and effectiveness of Focal Impulse and Rotor Modulation (FIRM)-guided ablation as the sole ablative strategy with PVI in patients with paroxysmal AF.Methods and resultsWe conducted a multicentre, randomized trial to determine whether FIRM-guided radiofrequency ablation without PVI (FIRM group) was non-inferior to PVI (PVI group) for treatment of paroxysmal AF. The two primary efficacy end points were (i) acute success defined as elimination of AF rotors (FIRM group) or isolation of all pulmonary veins (PVI group) and (ii) long-term success defined as single-procedure freedom from AF/atrial tachycardia (AT) recurrence 12 months after ablation. The study was closed early by the sponsor. At the time of study closure, any pending follow-up visits were waived. A total of 51 patients (mean age 63 ± 10.6 years, 57% male) were enrolled. All PVs were successfully isolated in the PVI group and all rotors were successfully eliminated in the FIRM group. Single-procedure effectiveness was 31.3% (5/16) in the FIRM group and 80% (8/10) in the PVI group at 12 months. Three vascular access complications occurred in the FIRM group.ConclusionThese partial study effectiveness results reinforce the importance of PVI in paroxysmal AF patients and indicate that FIRM-guided ablation alone (without PVI) is not an effective strategy for treatment of paroxysmal AF in most patients.

Long-term clinical outcomes and prognostic indicators for focal impulse and rotor modulation guided ablation: A single-center observational study

BackgroundElectrophysiologists have developed a computational mapping approach to localize sources that may perpetuate persistent atrial fibrillation (AF). Focal impulse and rotor modulation (FIRM)-guided ablation of these sources have produced variable results. The current study further assesses single-procedure success rates of FIRM-guided ablation for preventing AF or atrial tachyarrhythmia recurrence and analyzes different baseline characteristics as prognostic indicators for individuals experiencing these undesired outcomes. MethodsSeventy-one consecutive patients (mean age 64.58 ± 9.05 years and 36.6% female) with drug-refractory persistent AF with and without prior history of pulmonary vein antral isolation (PVAI) underwent FIRM-guided ablation. Patients without prior history of PVAI underwent FIRM-guided ablation in addition to de novo PVAI. Patients with prior history of PVAI had the pulmonary veins reassessed at the time of FIRM-guided ablation for reconnection as well as re-isolation, when necessary. These patients were then prospectively followed for AF and atrial tachyarrhythmia recurrence. ResultsFIRM analysis revealed rotors in the right atrium in 66.2% (1.77 ± 1.53 mean rotors per patient) and in the left atrium in 85.9% (2.65 ± 1.52 mean rotors per patient) of patients analyzed in the current study. After a single FIRM-guided ablation procedure, AF and atrial tachyarrhythmia recurrence was demonstrated in 21.1% (15/71) and 33.8% (24/71) of patients, respectively. The entire cohort of patients were followed for a mean duration of 23.20 ± 8.38 months with the mean time to AF recurrence found to be 12.35 ± 10.44 months. Furthermore, valvular heart disease (i.e. moderate mitral or tricuspid regurgitation) was found to be a statistically significant independent predictor for AF recurrence following FIRM-guided ablation (p = .033). ConclusionsFIRM-guided ablation in combination with PVAI is a suitable and effective approach for symptomatic individuals with drug-refractory persistent AF with and without prior history of PVAI. Randomized controlled studies are warranted.

Focal impulse and rotor modulation of atrial rotors during atrial fibrillation leads to organization of left atrial activation as reflected by waveform morphology recurrence quantification analysis and organizational index.

BackgroundFocal impulse and rotor modulation (FIRM) can cause slowing, organization, and occasionally termination of atrial fibrillation (AF), although results have been mixed. To further characterize changes in AF during rotor ablation, we quantified morphologic and temporal activation changes following FIRM.MethodsIn patients undergoing FIRM ablation for AF, we retrospectively analyzed coronary sinus bipolar EGMs before and after rotor ablation, including EGM activation frequency and regularity, dominant frequency (DF), and organizational index (OI). Changes in EGM waveform morphology were determined with recurrence quantification analysis (RQA) consisting of recurrence rate (RR), determinism (DET), laminarity (LAM), average diagonal line length (L), and trapping time (TT) using Wilcoxon signed‐rank testing.ResultsOverall, 36 rotors from 21 patients undergoing FIRM ablation were analyzed. All morphology RQA parameters demonstrated significant organization of atrial activation after rotor ablation (RR P = .03, DET P = .005, LAM P = .03, L P = .005, TT P = .009). The organizational index also showed a significant increase after rotor ablation (P = .01), and the change in OI correlated with changes in all morphology parameters. Of the rotors, 14/36 (39%) rotors showed organizational changes in all morphology parameters and OI, and an additional 5 rotors (19/36, 53%) showed organizational changes in 4 of 5 morphology parameters and OI.ConclusionsCoronary sinus EGM waveform morphologies and activation patterns are significantly altered after FIRM ablation even when there is no fibrillatory slowing. RQA morphology analysis and organizational index may impart important information regarding underlying AF organization and may be useful in quantifying the acute response to ablation.

P343Comparison of Focal Impulse and Rotor Modulation Ablation (FIRM) only versus second-generation cyroballoon ablation in patients with paroxysmal atrial fibrillation

Abstract Background Rotors have been postulated to be a major driver of atrial fibrillation (AF). Initial studies demonstrated, that focal impulse and rotor modulation (FIRM) might be an effective therapy for the treatment of paroxysmal AF (PAF). However, data about FIRM-guided ablation strategies without PVI is sparse. Objective To compare the safety and efficacy of FIRM-guided catheter ablation (without PVI; FIRM arm) and second generation cryoballoon (CB2, CB2 arm) based PVI in patients with paroxysmal atrial fibrillation (PAF) and de-novo catheter ablation of AF. Methods In this retrospective single-center study patients with PAF undergoing de-novo ablation of PAF between February 2016 and January 2017 were enrolled. Patients treated with FIRM-guided AF ablation as a standalone therapy without PVI were included and compared with patients undergoing CB2 based PVI. All patients in the FIRM arm were part of the randomized multicenter FIRMAP AF trial (results of this trial will be presented at this meeting). In patients undergoing FIRM-guided ablation, 3D electroanatomical mapping of both atria was performed. Rotor mapping using FIRM technology was conducted in spontaneous or induced AF. The procedural endpoint was the elimination of all rotors and focal impulses; no PVI was performed in those patients. In the CB2 arm, CB based PVI with the procedural endpoint of isolation of all veins was performed. Procedural data and arrhythmia-free survival after 12 months were compared. Results FIRM-guided and CB2 based AF ablation was performed in 22 and 86 patients, respectively. Follow up was completed in 20 and 79 patients LA diameter differed between groups. Otherwise, baseline characteristics did not differ between the FIRM group (mean age 60±11 years, 59.1% males) and the CB2 group (mean age 62±13, 62.4% male). Arrhythmia-free survival including a 90-day blanking period was 25.0% (15/20) in the FIRM group and 86.1% (11/79) in the CB2 PVI group (p=0.000; Figure 1). Procedure duration was significantly longer in the FIRM group (152 [120; 176] minutes) compared to the CB2 PVI group (122 [110; 145] minutes) (p=0.031), whereas radiation dose was lower in the FIRM group (1266 [1027; 2281] cGy·cm2 vs. 3020 [1677; 4215] cGy·cm2). Adverse events (groin complications) occurred in 1 patient (1.2%) in the CB2 PVI group and 5 patients (22.7%) in the FIRM group. Figure 1. Kaplan-Meier-survival curve dem Conclusion De novo ablation of PAF using a FIRM-guided AF ablation only (without PVI) is associated with poor arrhythmia-free survival after 12 months compared to CB2 PVI. These results underline the importance of PVI as the first-line approach in catheter ablation of AF.

P2846Focal impulse and rotor modulation ablation versus pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation (FIRMAP AF study)

Abstract Background Based on the assumption of trigger elimination, pulmonary vein isolation (PVI) currently presents the gold standard of atrial fibrillation (AF) ablation. Recently, rapidly spinning rotors or focal impulse formation has been raised as a crucial sustaining mechanism of AF. Ablation of these rotors may potentially obviate the need for trigger elimination with PVI. Purpose This study sought to compare the safety and effectiveness of Focal Impulse and Rotor Modulation (FIRM) guided catheter ablation only with the gold standard of pulmonary vein isolation (PVI) in patients with paroxysmal AF. Methods This was a post-market, prospective, single-blinded, randomized, multi-center trial. Patients were enrolled at three centers and equally (1:1) randomized between those undergoing conventional RF ablation with PVI (PVI group) vs. those treated with FIRM-guided RF ablation without PVI (FIRM group). Data was collected at enrollment, procedure, and at 7-day, 3-month, 6-month, and 12-month follow-up visits. The study was closed early by the sponsor. At the time of study closure, any pending follow-up visits were waived. Results From February 2016 until February 2018, a total of 51 (out of a planned 170) patients (mean age 63±10.6 years, 57% male) were enrolled and randomized. Four patients withdrew from the study prior to treatment, resulting in 23 patients allocated to the FIRM group and 24 in the PVI group. Only 13 patients in the FIRM group and 11 patients in the PVI group completed the 12-month follow-up. Statistical analysis was not completed given the small number of patients. Single-procedure effectiveness (freedom from AF/atrial tachycardia recurrence after blanking period) was 52.9% (9/17) in the FIRM group and 85.7% (12/14) in the PVI group at 6 months; and 31.3% (5/16) in the FIRM group and 80% (8/10) in the PVI group at 12 months. Repeat procedures were performed in 45.8% (11/24) patients in the FIRM group and 7.4% (2/27) in the PVI group. The acute safety endpoint [freedom from procedure-related serious adverse events (SAE)] was achieved in 87% (20/23) of FIRM group patients and 100% (24/24) of PVI group patients. Procedure related SAEs occurred in three patients in the FIRM group: 1 femoral artery aneurysm and 2 injection site hematomas. No additional procedure-related SAEs were reported &gt;7 days post-procedure. Conclusions These partial study effectiveness results reinforce the importance of PVI in paroxysmal atrial fibrillation patients and suggest that FIRM-guided ablation alone (without PVI) is not an effective strategy for treatment of paroxysmal AF in most patients. Further study is needed to understand the effectiveness of adding FIRM-guided ablation as an adjunct to PVI in this patient group. Acknowledgement/Funding Abbot

Single-center experience of the FIRM technique to ablate paroxysmal and persistent atrial fibrillation.

Focal impulse and rotor modulation (FIRM)-guided ablation has had mixed results of published success, and most studies have had a follow-up for a year or less. We aimed to study a consecutive group of patients followed for at least 1.5 years, subgrouped into those with an initial FIRM ablation and those with a previous, failed ablation who now received a FIRM guided one, to evaluate for success in each group and factors that might affect success. Of 181 patients, 167 were available for analysis. Group 1 (n = 122) had a first or primary ablation (paroxysmal atrial fibrillation [PAF] 51; persistent atrial fibrillation [PeAF] 71) and group 2 (n = 45) had a redo ablation (PAF 18; PeAF 27). All patients were done under general anesthesia. FIRM mapping was done in the right atrium first and then the left, and only rotors consistently seen on multiple epochs were ablated, using 15 to 30 W. Rotor ablation was discontinued when remapping showed elimination of rotational activity at the site. Wide area catheter ablation was done for pulmonary vein isolation (PVI). Routine follow-up was at 3, 6, and 12 months of the first year, with a Holter monitor at 6 months, and then every 6 months thereafter. Event recorders were given to patients with potential arrhythmic symptoms. Mean follow-up was 16 months. Nearly 40% of patients had obstructive sleep apnea; mean body mass index was 32; and average left atrial size was 39.7 mm and 46.2 mm for PAF and PeAF patients, respectively. Freedom from atrial arrhythmia recurrence was: in group 1 patients, 82.4% for PAF and 67.6% for PeAF patients; in group 2 patients, 83.3% for PAF, but only 40.7% for PeAF patients. Comparing outcomes for the first 10 patients studied to the next 20 or more done by three operators showed no difference, suggesting no learning curve affecting the ablation results. Furthermore, the univariate analysis did not show any demographic factor to have an independent significance for ablation success or failure. Spontaneous termination during rotor ablation occurred in 76.8% of PAF and 27.6% of PeAF patients but did not affect the long-term outcomes for maintenance of sinus rhythm. FIRM-guided atrial ablation plus PVI in our patient population resulted in good success from a recurrence of atrial arrhythmias in patients undergoing an initial ablation procedure. For those with persistent AF undergoing a second procedure now using FIRM guidance plus PVI, the results are lower. Further research is needed to define better the appropriate population for FIRM-guided ablation and the degree of ablation needed for success in these patients.

Targeting the Substrate in Ablation of Persistent Atrial Fibrillation: Recent Lessons and Future Directions.

While isolation of the pulmonary veins is firmly established as effective treatment for the majority of paroxysmal atrial fibrillation (AF) patients, there is recognition that patients with persistent AF have substrate for perpetuation of arrhythmia existing outside of the pulmonary veins. Various computational approaches have been used to identify targets for effective ablation of persistent AF. This paper aims to discuss the clinical aspects of computational approaches that aim to identify critical sites for treatment. Various analyses of electrogram characteristics have been performed with this aim. Leading techniques for electrogram analysis are Complex Fractionated Atrial Electrograms (CFAE) and Dominant Frequency (DF). These techniques have been the subject of clinical trials of which the results are discussed. Evaluation of the activation patterns of atria in AF has been another avenue of research. Focal Impulse and Rotor Modulation (FIRM) mapping and forms of Body Surface Mapping aim to characterize multiple atrial wavelets, macro-reentry and focal sources which have been proposed as basic mechanisms perpetuating AF. Both invasive and non-invasive activation mapping techniques are reviewed. The presence of atrial fibrosis causes non-uniform anisotropic impulse propagation. Therefore, identification of fibrosis by imaging techniques is an avenue of potential research. The leading contender for imaging-based techniques is Cardiac Magnetic Resonance (CMR). As this technology advances, improvements in resolution and scar identification have positioned CMR as the mode of choice for analysis of atrial structure. AF has been demonstrated to be associated with obesity, inactivity and diseases of modern life. An opportunity exists for detailed computational analysis of the impact of risk factor modification on atrial substrate. This ranges from microstructural investigation through to examination at a population level via registries and public health interventions. Computational analysis of atrial substrate has moved from basic science toward clinical application. Future directions and potential limitations of such analyses are examined in this review.

Rotor mapping: black box or very simple? The FIRM approach.

Catheter ablation has become the most common therapy in patients with atrial fibrillation (AF). However, despite significant advances in technology and operators' experience, ablation outcomes remain suboptimal, especially in patients with persistent AF. Focal impulse and rotor modulation (FIRM) represents anew technology for mapping and ablation of patient-specific AF sources. This approach is based on the concept of localized sources, which can be understood as organized rotational waves or focal impulses driving disorganized AF. Several studies, mainly single-center case series, have shown an incremental benefit in long-term outcome when adding FIRM-guided ablation to conventional pulmonary vein isolation (PVI). Therefore, the results of ongoing multicenter randomized trials are needed to support this data.

Clinical Implications of Ablation of Drivers for Atrial Fibrillation: A Systematic Review and Meta-Analysis.

The outcomes from pulmonary vein isolation (PVI) for atrial fibrillation (AF) are suboptimal, but the benefits of additional lesion sets remain unproven. Recent studies propose ablation of AF drivers improves outcomes over PVI, yet with conflicting reports in the literature. We undertook a systematic literature review and meta-analysis to determine outcomes from ablation of AF drivers in addition to PVI or as a stand-alone procedure. Database search was done using the terms atrial fibrillation and ablation or catheter ablation and driver or rotor or focal impulse or FIRM (Focal Impulse and Rotor Modulation). We pooled data using random effects model and assessed heterogeneity with I2 statistic. Seventeen studies met inclusion criteria, in a cohort size of 3294 patients. Adding AF driver ablation to PVI reported freedom from AF of 72.5% (confidence interval [CI], 62.1%-81.8%; P<0.01) and from all arrhythmias of 57.8% (CI, 47.5%-67.7%; P<0.01). AF driver ablation when added to PVI or as stand-alone procedure compared with controls produced an odds ratio of 3.1 (CI, 1.3-7.7; P=0.02) for freedom from AF and an odds ratio of 1.8 (CI, 1.2-2.7; P<0.01) for freedom from all arrhythmias in 4 controlled studies. AF termination rate was 40.5% (CI, 30.6%-50.9%) and predicted favorable outcome from ablation(P<0.05). In controlled studies, the addition of AF driver ablation to PVI supports the possible benefit of a combined approach of AF driver ablation and PVI in improving single-procedure freedom from all arrhythmias. However, most studies are uncontrolled and are limited by substantial heterogeneity in outcomes. Large multicenter randomized trials are needed to precisely define the benefits of adding driver ablation to PVI.

Cost effectiveness of focal impulse and rotor modulation guided ablation added to pulmonary vein isolation for atrial fibrillation.

Although ablation with focal impulse and rotor modulation (FIRM), as an adjunct to pulmonary vein isolation (PVI), has been shown to decrease atrial fibrillation (AF) recurrence, cost-effectiveness has not been assessed. We aimed to evaluate the cost effectiveness of FIRM-guided ablation when added to PVI in a mixed AF population. We used a Markov model to estimate the costs, quality-adjusted survival, and cost effectiveness of adding FIRM ablation to PVI. AF recurrence rates were based on 3-year data from the CONFIRM trial. Model inputs for event probabilities and utilities were obtained from literature review. Costs were based on Medicare reimbursement, wholesale acquisition costs, and literature review. Three-year total costs FIRM+PVI versus PVI alone were $27,686versus $26,924. QALYs were 2.338versus 2.316, respectively, resulting in an incremental cost-effectiveness ratio (ICER) of $34,452 per QALY gained. Most of the cost (65-81%) was related to the index ablation procedure. Lower AF recurrence generated cost offsets of $4,266, primarily due to a reduced need for medications and repeat ablation. Probabilistic sensitivity analysis demonstrated ICER below $100,000/QALY in 74% of simulations. Based on data from the CONFIRM study, the addition of FIRM to PVI does have the potential to be cost-effective due to higher quality-adjusted life years and lower follow-up costs. Value is sensitive to the incremental reduction in AF recurrence, and FIRM may have the greatest economic value in patients with greater AF symptom severity. Results from ongoing randomized trials will provide further clarity.

Long-Term Outcome of Pulmonary Vein Isolation With and Without Focal Impulse and Rotor Modulation Mapping: Insights From a Meta-Analysis.

This meta-analysis systematically evaluated the outcome of pulmonary vein isolation (PVI) with and without focal impulse and rotor modulation (FIRM) ablation in patients with atrial fibrillation. Extensive literature search was performed for studies reporting outcomes of PVI alone and PVI+FIRM procedures. For PVI alone, only randomized trials conducted in the past 3 years reporting single-procedure off-antiarrhythmic drugs success rate at ≥12-month follow-up were included. In PVI+FIRM group, all published studies reporting single-procedure off-antiarrhythmic drugs success rate with at least 1-year follow-up were identified. Meta-analytic estimates were derived using DerSimonian and Laird random-effects models, and pooled estimates of success rate (95% confidence interval) were computed. Statistical heterogeneity was assessed using Cochran Q test and I2. Study quality was assessed using Newcastle-Ottawa Scale. Fifteen trials were included, 10 with PVI+FIRM (n=511, nonrandomized prospective design), and 5 with PVI-only trials (n=295, randomized trials). All patients in PVI-only trials had 100% nonparoxysmal atrial fibrillation, except 1 study, and no prior ablations. About 24% of PVI+FIRM population had paroxysmal atrial fibrillation. After 15.9±5.5 (median 12) months follow-up, the off-antiarrhythmic drugs pooled success rate was 50% in FIRM+PVI (95% confidence interval, 28%-72%) and 58% in PVI (95% confidence interval, 46%-71%). Difference in effect size between groups was not statistically significant (P=0.21). No significant heterogeneity (total or within group) was observed in this meta-analysis (negative I2 values considered equal to zero). The overall pooled estimate did not show any therapeutic benefit of PVI+FIRM approach over PVI alone, which suggests the need to reevaluate the clinical use of FIRM ablation in atrial fibrillation.

Type and rate of atrial fibrillation termination due to rotational activity ablation combined with pulmonary vein isolation.

There remains controversy about the optimal ablation technique and termination rate of atrial fibrillation (AF) during catheter ablation in patients with persistent AF. The aim of this study was to determine the rate and timing of AF termination during combined pulmonary vein isolation (PVI) and focal impulse and rotor modulation (FIRM)-guided ablation of rotational activity (RoAc). This single-center, prospective cohort study enrolled 38 consecutive patients (63% male, mean age 63 ± 11 years) with persistent AF (mean left atrial size: 46 ± 7 mm), who underwent FIRM mapping and ablation of the identified RoAcs followed by PVI. We systematically evaluated the incidence and timing of AF termination during AF ablation. "Late-onset termination" of AF could be observed in 12 (32%) patients after ablation of the identified RoAcs. In a further 10 (26%) patients, "abrupt" AF termination during PVI was achieved. In total, the combined technique of conventional PVI and RoAc ablation resulted in AF termination rate of 58%. ECV was performed in 16 "nonterminating" patients. At 1-year follow-up, 76.1% (16 of 21) of patients remained free from AF/AT, 4 of 10 patients (25%) within the "abruptly" terminated group, 7 of 12 (58.3%) patients among the "late-terminated" group, and 5 of 16 (31, 25%) patients in the "nonterminating" group. Large area RoAc ablation combined with PVI results in a moderate termination rate of persistent AF with two distinctive timing patterns. More studies are needed to determine the clinical significance of type of AF termination and long-term success rate of RoAc ablation in patients with persistent AF.

P362Minimizing fluoroscopy during focal impulse and rotor modulation (FIRM) guided ablation for atrial fibrillation

P362Minimizing fluoroscopy during focal impulse and rotor modulation (FIRM) guided ablation for atrial fibrillation

Clinical Benefit of Ablating Localized Sources for Human Atrial Fibrillation: The Indiana University FIRM Registry

BackgroundMounting evidence shows that localized sources maintain atrial fibrillation (AF). However, it is unclear in unselected “real-world” patients if sources drive persistent atrial fibrillation (PeAF), long-standing persistent atrial fibrillation (LPeAF), or paroxysmal atrial fibrillation (PAF); if right atrial sites are important; and what the long-term success of source ablation is. ObjectivesThe aim of this study was to analyze the role of rotors and focal sources in a large academic registry of consecutive patients undergoing source mapping for AF. MethodsOne hundred seventy consecutive patients (mean age 59 ± 12 years, 79% men) with PAF (37%), PeAF (31%), or LPeAF (32%). Of these, 73 (43%) had undergone at least 1 prior ablation attempt (mean 1.9 ± 0.8; range: 1 to 4). Focal impulse and rotor modulation (FIRM) with an endocardial basket catheter was used in all cases. ResultsFIRM analysis revealed sources in the right atrium in 85% of patients (1.8 ± 1.3) and in the left atrium in 90% of patients (2.0 ± 1.3). FIRM ablation terminated AF to sinus rhythm or atrial flutter or tachycardia in 59% (PAF), 37% (PeAF), and 19% (LPeAF) of patients, with 15 of 67 terminations due to right atrial ablation. On follow-up, freedom from AF after a single FIRM procedure for the entire series was 95% (PAF), 83% (PeAF), and 82% (LPeAF) at 1 year and freedom from all atrial arrhythmias was 77% (PAF), 75% (PeAF), and 57% (LPeAF). ConclusionsIn the Indiana University FIRM registry, FIRM-guided ablation produced high single-procedure success, mostly in patients with nonparoxysmal AF. Data from mapping, acute terminations, and outcomes strongly support the mechanistic role of biatrial rotors and focal sources in maintaining AF in diverse populations. Randomized trials of FIRM-guided ablation and mechanistic studies to determine how rotors form, progress, and regress are needed.

Focal Impulse and Rotor Modulation for the Treatment of Atrial Fibrillation: Locations and 1 Year Outcomes of Human Rotors Identified Using a 64-Electrode Basket Catheter.

Pulmonary vein isolation (PVI) is currently the gold standard for catheter ablation of atrial fibrillation (AF). The mechanism for AF-maintenance is still controversial. The concept of rapidly activating spiral rotors perpetuating AF has led to the development of several rotor-mapping systems. We present our experience with focal impulse and rotor modulation (FIRM) using a 64-electrode basket catheter and computational system and evaluate its feasibility in conjunction with PVI to treat AF. Twenty-five patients underwent FIRM mapping and ablation to treat AF (paroxysmal = 10, 40%). A basket catheter was used for rotor identification within the right atrium (RA) then left atrium (LA). Radiofrequency energy was applied at and around each rotor core for 300 seconds and rotor-mapping and ablation was repeated until all rotors were eliminated before circumferential PVI was performed. Three (1.0, 4.0) rotors were identified per patient, predominantly in the LA (LA = 59). Note that 7/59 left-sided rotors were located 8/59 at the PV antrum. Twelve (48%) patients had either AF termination (termination = 6/12) or conversion to another rhythm, or cycle length (CL) prolongation ≥10% after rotor ablation. After a single procedure, 13 (52%) patients were free of atrial tachyarrhythmia after a follow-up period of 13 ± 1 months. Early results suggest that FIRM-ablation can terminate AF in a significant number of patients. Rotors were frequently identified in the PVs and PV antrum, supporting PVI as the cornerstone of AF ablation.

Practical Aspects of Rotor Mapping in Catheter Ablation of Atrial Fibrillation

Historically, pulmonary veins have been the focus of atrial fibrillation (AF) ablation therapy, but it is increasingly being recognized that localized electric rotors and focal impulse sources have a role in maintaining AF. Targeting of these sources using focal impulse and rotor modulation (FIRM)-guided ablation has resulted in elimination of the source and improved long-term outcomes. FIRM uses wide-area mapping of both atria in AF, using commercially-available basket catheters (to provide contact electrograms). However, not all data support the use of FIRM. This paper provides a description of rotor mapping and ablation. In addition, practical strategies for optimizing the technique are discussed, including: catheter positioning; accurate diagnosis of the presence and locations of focal sources; and amount of ablation performed in regions with rotors or foci.

Abstract 13948: High Intraprocedural Atrial Fibrillation Termination Rate by Large Area Rotor Ablation Combined With Pulmonary Vein Isolation

Introduction: There remains contradictory data about the optimal ablation technique and the type of termination of atrial fibrillation (AF) ablation particularly in patient (pt) with persistent AF. The aim of this study was to determine the type of the termination of persistent AF during combined conventional and rotor ablation. Method: This is a single-center, prospective, observational study enrolled thirty-eight pts (24/63% male, mean age 63 years) with AF (mean left atrial size: 46,2 ± 7 mm), who underwent focal impulse and rotor modulation (FIRM) mapping and large area ablation around the core of the identified rotor(s), followed by conventional pulmonary vein isolation(PVI) using contact force catheter aiming 10-20 gr depending on the location. Two distinctive types of the AF termination were defined: sub-acute termination related to rotor elimination, furthermore acute termination due to PVI. Electric cardioversion (ECV) was executed only in the absence of spontaneous conversion to sinus rhythm (SR). Result: In 10(26%) pts acute AF termination after PVI was observed. In further 12 (31%) pts sub-acute termination of the AF could be observed after the identified rotor ablation. The combined technique of conventional and rotor ablation of pts with persistent AF resulted in 57,8% of termination rate. Spontaneous cardioversion could not be reached in 16 (42%) pts however 15 out of them were converted to SR by ECV. Procedural complication occurred in 3 pts presenting with groin hematoma, in one patient left atrial appendage (LAA) thrombus was revealed by transoesophageal echocardiography performed right after the ablation for guiding the planned LAA closure. Conclusion: Large area rotor ablation drag technique combined with contact force sensing technique results in a high termination rate of persistent AF. More studies are warranted to define the clinical significance and long term success rate of rotor ablation in pts with persistent atrial fibrillation.