Left Atrium Substrate Research Articles

Left atrium substrate and wave speed mapping using Omnipolar technology in patients undergoing paroxysmal atrial fibrillation catheter ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background The new Ensite X Cardiac Mapping (Abbott) system, with the introduction of Omnipolar technology (OT), provides three-dimensional information on voltage, direction of activation and conduction velocity of endocardial potentials, regardless of catheter orientation. OT thus enables the creation of more defined voltage maps and a wave speed map, a color map encoded by the numerical value of conduction velocity. Purpose We aimed to evaluate the feasibility and reliability of left atrium (LA) substrate and wave speed mapsperformed with OT in patients undergoing pulmonary vein isolation of paroxysmal atrial fibrillation (AF). Methods We included 39 patients undergoing catheter ablation for paroxysmal AF with the new Ensite X Cardiac Mapping System at five Italian Institution. In all patients the left atrium (LA) was mapped with the Advisor HD Grid catheter (Abbott). A sinus rhythm high-density voltage map and wave speed map were obtained and analyzed to compare low-voltage areas and to identify high conduction velocity areas. Results Thirty-nine pts were included in this analysis (61±10 years, 64% male, 68% with paroxysmal AF, CHA2DS2-VASc = 1.6±1.1, left atrial diameter = 46±9 mm, left ventricle ejection fraction 63±4%). The voltage maps were obtained by acquiring and, after point validation, analyzing significantly more points in the OT analysis than in the bipolar analysis (11455±8833 vs 8186±5826 and 2611±1728 vs 1753±1324, respectively; p < 0.001). Low-voltage area (< 0.05 mV) was significantly less extensive using OT (low-voltage OT area 8.9 cm2 [5.8; 24.2] vs low-voltage bipolar area 10.8 [6.4; 31.4]; p < 0.05), Fig 1. Considering wave speed maps, the pulmonary veins showed significantly higher values than the atrial values (LSPV: 2.89 ms/s ± 1.99; LIPV 2.86 ms/s ± 1.78; RSPV 3.31 ms/s ± 2.07; RIPV 2.86 ms/s ± 1.96; LA 1.67 ms/s ± 0.80; p< 0.001) while, in the atrium, the area of greatest speed was located on the roof (2.35 ms/s ± 1.53; p 0.02) almost drawing a bundle from the RSPV to the LA appendage that could coincide with the anatomical Bachmann’s bundle location, Fig 2. Conclusion OT makes it possible to obtain voltage maps by analyzing a larger number of points and providing a better substrate definition. Wave speed mapping is a promising new map type, allowing characterization and identification of high velocity areas. Further studies are needed to assess the impact of this new technology on procedural workflow and clinical outcome.

Uric acid significantly correlates with the presence of low-voltage areas at the endocardial mapping in patients with non-valvular atrial fibrillation

Background and aimsInterest in the role of atrial substrate in maintaining Atrial Fibrillation (AF) is growing. Fibrosis is the culprit in the electrical derangement of the myocytes. Many cardiovascular risk factors are known to be linked to atrial scarring; among them Uric Acid (UA) is emerging. The purpose of our study is to find whether UA is associated with Left Atrium (LA) with pathological substrate. Methods and results81 patients who underwent radiofrequency transcatheter ablation for nonvalvular AF at the cardiological department of the Niguarda Hospital were enrolled in an observational, cross-sectional, single-center study. UA levels were analysed before the procedure. High density electroanatomic mapping of the LA was performed and patients were divided according to the presence or not of areas of pathological substrate (bipolar voltage <0.5 mV in sinus rhythm). 19 patients showed a LA with pathological substrate. These subjects showed a significant higher prevalence of persistent phenotype of AF (84.2 vs. 25.8%, p < 0.001). UA levels were significantly higher in the group of patients with LA with pathological substrate (6.8 ± 1.9 vs 5.3 ± 1.4 mg/dL, p < 0.001) as well as the prevalence of hyperuricemia (26.5 vs. 6.5%, p = 0.021). The association between uric acid LA with pathological substrate remains significant even after correction for confounding factors (age, left ventricular dysfunction, valvular disease, arrythmia phenotype and furosemide use) and also when the ratio UA/creatinine was evaluated. ConclusionsIn a population of patients who underwent AF ablation, higher UA levels were significantly associated with pathological LA substrate at electro-anatomical mapping.

Circumferential Pulmonary Vein Isolation Plus Low-Voltage Area Modification in Persistent Atrial Fibrillation: The STABLE-SR-II Trial.

Benefits of adjunctive ablation strategies beyond circumferential pulmonary vein isolation (CPVI) are uncertain in patients with persistent atrial fibrillation (PeAF). This study sought to compare clinical outcomes of CPVI plus low-voltage area (LVA) modification during STABLE-SR (SubsTrate ABlation in the LEft Atrium during Sinus Rhythm) vs circumferential pulmonary vein isolation (CPVI) alone in patients with PeAF. From March 2018 to August 2019, 300 patients with PeAF who underwent de novo ablation were recruited and prospectively randomized to either STABLE-SR group (n=150) or CPVI alone (n=150) group. In the STABLE-SR group, after CPVI, high-density voltage mapping of left atrium (LA) was performed during sinus rhythm, and additive ablation targeted LVA and complex electrograms, if any were present. All the ablations were titrated by ablation index. The primary endpoint was freedom from documented atrial arrhythmias lasting for≥30s without the use of antiarrhythmic drugs, after a single ablation procedure and blanking period of 3months. After 18months, atrial-arrhythmia-free survival did not differ significantly between STABLE-SR group and CPVI alone group (67.2% vs 67.4%; HR: 0.89; 95%CI: 0.55-1.36; P = 0.52). Only around one-half of the patients (50.2%) had abnormal LA substrate with a medium LVA burden of 4.6% (2.1%-9.5%). However, the success rate differs dramatically between patients with normal vs abnormal LA substrate (84.8% vs 60.9%; P< 0.001). Additional LVA ablation did not improve successful rates of CPVI in this PeAF cohort, of whom one-half had normal LA substrate. Voltage map could identify patients with PeAF with normal LA substrate who can achieve excellent rhythm control with CPVI alone. (CPVI Alone Versus CPVI Plus Electrophysiological Substrate Ablation in the LA During SR for the Treatment of Non-PAF [STABLE-SR_II]; NCT03448562).

Find me if you can: lessons learned using the novel cartofinder algorithm in a routine workflow for catheter ablation of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background CARTOFINDER allows for a simultaneous and automated detection of repetitive focal and rotational activations during electroanatomical mapping using a multi-electrode catheter in patients with atrial fibrillation (AF). Aim This study aimed to validate the CARTOFINDER algorithm for the detection of potential drivers for AF under routine clinical conditions and to access the effects of PVI and additional substrate modification on regions of interests (ROI) from CARTOFINDER mapping. Methods Forty-four consecutive patients underwent AF ablation for persistent AF using a 3D-mapping system with the novel integrated CARTOFINDER module. All patients presented with persistent AF and mapping was performed using a multi-electrode catheter. The ablation workflow was divided into the following steps: 1. 3D reconstruction of the right (RA) and left atrium (LA). 2. Identification of the individual ROIs separated for focal and rotational activity in the RA and LA. 3. Ablation index guided pulmonary vein isolation (PVI). 4. Repeat mapping for ROIs in the RA and LA. 5. Direct current electrical cardioversion. 6. Confirmation of persistent PVI and bipolar ultra-high density mapping of the RA and LA followed by substrate modification if there was evidence for local bipolar low-voltage in the LA. Results Acute PVI was achieved in all patients (100%). In 28% of these patients additional LA substrate modification was performed. AF termination was observed in 4 patients. Mean procedure duration was 137 ± 30 min, mapping time for ROIs in the RA was 8 ± 5 min and 11 ± 5 for the LA, respectively. A mean number of 149 ± 82 ROIs were revealed from CARTOFINDER. In the LA, focal activity was predominantly observed inside the LA appendage (LAA) and in close relationship to the pulmonary vein ostia. The majority of rotational activities was found along the mitral valve annulus. In the RA, the majority of ROIs was found at the septum and in close relationship to the RA appendage. During re-mapping for ROIs after AF ablation we observed the elimination of ROIs close to the linear ablation set for PVI. In addition, rotational activity could not be re-identified at repeat mapping. Conclusions ROIs could be discriminated and visualized utilizing CARTOFINDER in all patients. These ROIs might potentially be an additional and individual ablation target beyond PVI in patients with persistent AF.

Abstract 17472: Association of Recurrence During Blanking Period With Poor Left Atrial Reverse Remodeling After Initial Catheter Ablation of Non-paroxysmal Atrial Fibrillation: Their Impact on the Clinical Outcome

Background: Left atrial reverse remodeling (LARR) after catheter ablation (CA) to atrial fibrillation (AF) indicates reduction of AF substrates in left atrium (LA). In this study, we investigated the impact of LARR on the outcome after CA of non-paroxysmal AF (non-PAF; persistent AF and long-standing persistent AF) and determined the predictor of LARR. Methods and Results: Consecutive 303 patients who underwent initial CA of non-PAF in our institute were retrospectively analyzed. We performed multi-detector computed tomography (MDCT) to evaluate LA end-systolic volume (LAESV) before and 90 days after CA. We determined LARR using %LA reduction [defined as (pre LAESV - post LAESV) / pre LAESV x100]. The average %LA reduction was 20.2±16.8% (median 22.2%). Then we divided them into LARR group (%LA reduction &gt;20%, N=167) and non-LARR group (%LA reduction&lt;20%, N=136). We followed them for 630±153 days to observe their recurrence rate after 90 days blanking period (BP). The recurrence was less frequently observed in LARR group than non-LARR (31.1% vs 56.4%, p&lt;0.01, log-rank test). Next, we examined the predictor of LARR. In univariate analysis, there were no significant differences in age, sex, CHADS2 score, AF duration before CA, anti-arrhythmic drug administration after CA, CA procedure, echocardiographic data and MDCT parameters. Only the recurrence rate during BP was significantly smaller in LARR than non-LARR (43% vs 61%, p=0.002). Then, we divided BP into three parts, early BP, mid BP and late BP (within 7 days, 8 to 30 days, and 31 to 90 days after CA, respectively). The recurrence rate in LARR group was lower than in non-LARR during early BP (27.5% vs 36.8%, p=0.09), mid BP (30.5% vs 42.6%, p=0.03), and late BP (9.0% vs 31.6%, p&lt;0.01). In multivariable analysis, recurrence in late BP revealed to be the predictor of LARR (odds ratio 0.19, [95% confidence interval: 0.10-0.37]). Conclusions: The LARR was associated with better clinical outcome. The absence of recurrence during late BP (31-90 days after CA) was the strong predictor of LARR. These parameters can be acquired at the time point of 3 months after CA and they may be useful for predicting the CA results. Recurrence during late BP might be one of the causes of the poor LARR after CA for non-PAF.

Differences in the Atrial Electrophysiological Properties Between Vagal and Sympathetic Types of Atrial Fibrillation

Autonomic modulation of the cardiac activity plays an important role in the pathogenesis of atrial fibrillation (AF). The aim of this study was to assess the differences in the atrial electrical and structural properties between patients with vagal and sympathetic AF. The study included 30 patients (53 ± 12 years old, male 26) with frequent attacks of symptomatic paroxysmal AF. All cases underwent 24-hour ambulatory Holter monitoring before the catheter ablation. The onset of AF accompanied with an increased HF component and decreased L/H ratio was designated as a vagal type (group 1, n = 12), whereas a decreased HF component and increased L/H ratio was classified as a sympathetic type (group 2, n = 18). Electrical and structural properties were evaluated during the ablation procedure. All patients had AF originating from PVs. There was a higher incidence of non-PV triggers in group 2 patients than that in group 1 (44% vs 8%, P = 0.04). Group 1 had a higher bipolar peak-to-peak voltage and mean DF of the global left atrium (LA), shorter total activation time, and smaller LA volume than group 2, whereas the electrical and structural properties in the right atrium were similar. After a follow-up of 15 ± 7 months, there was a lower incidence of AF recurrence in group 1 than that in group 2 (0% vs 28%, P = 0.02). There are better electrical properties and a smaller LA volume in patients with vagal-type AF. In contrast, the LA substrate is worse, and coexisting non-PV triggers and recurrence following ablation are more prevalent in patients with the sympathetic-type AF.

Differences of Atrial Electrophysiological Properties between Vagal and Sympathetic Type Atrial Fibrillations

Introduction: Autonomic modulation of cardiac activities plays an important role in the pathogenesis of atrial fibrillation (AF). The aim of this study was to assess the differences of atrial electrical/structural properties between the patients with vagal and sympathetic AF. Methods: The study included 16 patients (53±12 y/o, male 14) with frequent attacks of symptomatic paroxysmal AF. All cases underwent 24-hour ambulatory Holter monitoring before ablation. Onset of AF accompanied with increased HF component and decreased L/H ratio was designated as vagal AF (Group 1, n=8); whereas decreased HF component and increased L/H ratio was classified as sympathetic AF (Group 2, n=8). Electrical/structural properties were evaluated. Results: All patients had AF originating from PVs. There was a higher incidence of non-PV triggers in Group 2 patients than Group 1 (50% vs. 0%, p=0.02). Group 1 had a higher bipolar peak-to-peak voltage of left atrium (LA), longer activation time and smaller LA volume than those of Group 2, whereas electrical and structural properties in the right atrium were similar. After a follow-up of 9±4 months, there was a lower incidence of AF recurrence in Group 1 than Group 2 (0% vs. 50%, p=0.02). Conclusion: There is a better electrical property with smaller LA volume in the patients with vagal AF. The LA substrate is worse, and the coexisting non-PV triggers and recurrence following ablation are more prevalent in the patients with sympathetic AF.

Role of high dominant frequency sites in nonparoxysmal atrial fibrillation patients: Insights from high-density frequency and fractionation mapping

The adjunctive role of dominant frequency (DF) mapping during complex fractionated electrogram (CFE) ablation of atrial fibrillation (AF) has not been clarified. The purpose of this study was to investigate whether DF distribution or substrate properties are related to fibrillatory activity in the left atrium (LA) and to evaluate the effect of CFE ablation on the different patterns of DF distribution. The study enrolled 50 nonparoxysmal AF patients who underwent mapping, pulmonary vein isolation, and CFE ablation. High-density DF and CFE mapping were performed from the center of DF(max) centrifugally to the rest of the LA. The LA substrate was classified into two types depending on the presence of intra-LA DF gradients as type 1 (>20% of the average DF) or type 2 (<20% of the average DF). In type 1, maximal CFE and DF gradients were observed at the boundary (n = 14) or center (n = 16) of the DF(max) region. In type 2 (n = 20), less intra-LA DF gradient was observed (4.27 +/- 1.92 Hz vs 1.14 +/- 0.52 Hz for types 1 and 2, P <.001) and a large proportion of continuous CFEs extended from the center of DF(max) (19% +/- 11% and 42% +/- 15% of the LA for types 1 and type 2, P = .001). The procedure termination rate and long-term sinus rhythm maintenance rate were lower in patients with a smaller DF gradient (P <.05). The spatial distribution of fractionated activity was associated with particular DF patterns in nonparoxysmal AF patients. Patients with an evident intra-LA DF gradient responded better to pulmonary vein isolation and continuous CFE ablation.

THE STRATEGY OF CATHETER ABLATION FOR PERSISTENT/PERMANENT ATRIAL FIBRILLATION IN THE PATIENTS WITH IMMEDIATE RECURRENCE AFTER CARDIOVERSION

Abstract Category: Clinical Electrophysiology--Supraventricular ArrhythmiasPresentation Number: 1136-147Authors: Koichi Inoue, Toshiya Kurotobi, Ryusuke Kimura, Yuko Toyoshima, Norihisa Ito, Katsuomi Iwakura, Cardiovascular Center, Sakurabashi-Watanabe Hospital, Osaka, Japan Background: Intensive catheter ablation (CA) of substrates in left atrium (LA) is performed to persistent/permanent atrial fibrillation (peAF). Several mechanisms have been proposed for AF, and unnecessary intensive LA substrate modification could be avoided if the contributing mechanism is specified in each patient.Method: The consecutive 201 patients who underwent circumferential pulmonary vein (PV) isolation to peAF were studied. We performed cardioversion at the beginning of the CA procedure, and observed the presence or absence of immediate recurrence of AF (IRAF), which was defined as AF recurrence within 90 seconds after restoration of sinus rhythm. We followed the patients with IRAF for 14 +/- 8 months, and investigated the incidence of AF recurrence and its mechanism.Result: IRAF was observed in 56 patients (56/202 patients, 28%). All IRAF was triggered by short-coupled premature atrial contractions (PACs). Most of triggering PACs were originated from PVs (52/65 foci, 80%), and 46 out of 56 patients (82%) had PVs which generated the triggering PACs (trigger-PVs). All PVs were successfully isolated during the first procedure. The recurrence was observed in 13 patients (28%) and another session of CA was performed in 10 patients (22%). In these patients, a reconnection of electrical LA-PV conduction was more frequently observed in the trigger-PV than in non-trigger-PV (9/14 PVs (64%) vs. 7/26 PVs (27%), p<0.05). All reconnected PVs were successfully re-isolated, and majority of the patients (41/46 patients, 89%) successfully maintained sinus rhythm.Conclusion: In patients showing IRAF which was triggered by PAC from PVs, the recurrence of AF was mostly due to the restoration of electrical conduction between LA and these PVs. The elimination of PV potentials is especially important, and intensive LA substrate ablation might be unnecessary in these patients.

Pulmonary Edema After Extensive Radiofrequency Ablation for Atrial Fibrillation

More extensive ablation strategies for the treatment of atrial fibrillation (AF) have increased success rates but are associated with new and sometimes serious complications. We describe a new complication after extensive radiofrequency (RF) ablation in the left atrium (LA) for persistent AF. Electroanatomic guided circumferential ablation around both ipsilateral pulmonary veins (PV) was performed with the endpoint of complete conduction block. When necessary, supplementary RF applications were added, including ablation of complex fractionated potentials and/or isolation of other thoracic veins and/or linear left atrial lesions. RF energy was delivered via an irrigated tip catheter with a maximum power of 30-35 W. Four out of 120 patients undergoing extensive RF ablation for persistent AF (including two patients with additional LA substrate modification) developed dyspnea, bilateral pulmonary edema, and signs of a systemic inflammatory response syndrome (SIRS) (rise in body temperature, leukocyte count, and C-reactive protein (CRP levels) 18-48 hours after the procedure. There were no signs of PV stenosis, focal lung injury, left ventricular dysfunction, circulatory failure, or infection. All patients had complete recovery with supportive therapy within 3-4 days after the onset of symptoms. Extensive LA radiofrequency ablation bears the risk of a severe pulmonary edema. Although the precise mechanism is elusive, clinical features point toward a systemic inflammatory response.

Spectral analysis during sinus rhythm predicts an abnormal atrial substrate in patients with paroxysmal atrial fibrillation

Regions of rapid and multiple deflections can be identified with high dominant frequency (DF) during sinus rhythm (SR). These areas may play a role in the perpetuation of atrial fibrillation (AF) and indicate an atrial substrate abnormality. The purpose of this study was to investigate the atrial substrate properties of the high-frequency sites in patients with paroxysmal AF. Forty patients (52 +/- 12 years of age) with paroxysmal AF were studied using a three-dimensional mapping system. Spectral analysis was performed on the bipolar electrograms in the left atrium (LA) during SR. Overall, 7708 electrograms were analyzed, and the DFs higher than 70 Hz were labeled as abnormal. The regional distribution of the high-DF sites in the LA could be divided into two types. Type 1 includes high-DF sites existing only in the pulmonary veins (PVs; n = 19, 6.6 +/- 3.4 sites/patient). Type 2 includes high-DF sites in the LA or LA plus the PVs (n = 21, 11 +/- 5.6 sites/patient). In type 1, PV isolation (PVI) could eliminate the AF with negative AF inducibility testing after the PVI in 89% of patients. In type 2, additional LA substrate modification was needed in 81% of patients because sustained AF was induced after the PVI (P<.001, compared with type 1). Multivariate analysis showed that the lower mean voltage of the LA and high-frequency sites distribution both independently predicted a positive AF inducibility after the PVI (P<.05). Spectral analysis during SR can detect an abnormal atrial substrate. A regional distribution of the high-DF sites predicts the efficacy of the PVI.