Multipolar Catheter Research Articles

Discordance between left atrial volume and scar burden in patients with atrial fibrillation and its impact on atrial fibrillation recurrence after catheter ablation

Abstract Background Large left atrial (LA) volume and a high burden of LA low voltage zone (LVZ) are associated with atrial fibrillation (AF) recurrence after AF catheter ablation. There is a scarcity of information on the association between LA volume and LVZ and its impact on the risk of AF recurrence. Purpose To investigate the relationship between the LA volume and LVZ, as well as how these factors contribute to the recurrence of atrial fibrillation (AF). Methods From Nov 2021 to Oct 2023, drug-refractory AF patients who underwent AF catheter ablation were included. LA volume was assessed using the LA volume index (LAVI) using echocardiography. The LVZ was evaluated by conducting high-density electroanatomical mapping using a multipolar catheter. The cut-off value associated with AF recurrence was 48ml/m2 in LAVI and 4.5% in scar burden. Patients were categorised into four groups according to the LAVI and scar burden: Group 1 (Low LVZ and small LA), group 2 (Low LVZ and large LA), group 3 (High LVZ and small LA), and group 4 (High LVZ and large LA). Results A total of 170 patients were included (mean age 62± 9 years, 82% of men, 68.2% of non-paroxysmal AF and 81 [48%] in group 1; 32 [19%] in group 2, 27 [16%] in group 3, 30 [17%] in group 4, respectively). Among total, mean follow-up duration was 266.5 ± 174.4 days, and 8.8% of patients received additional LA ablation beyond pulmonary vein isolation. Among the four groups, group 2 and 4 were significantly associated with higher risks of AF recurrence compared to group 1 (HR 2.36 [1.04-5.34], p=0.039; 3.56 [1.59-7.95], p=0.002, respectively). The risk of AF recurrence was highest in group 4, followed by group 2 (log-rank P=0.002). Comparing group 2 and 3, AF recurrence occurred predominantly within 6-month after catheter ablation in group 2, while after 1-year in group 3 (log-rank P=0.83). Conclusion About one-third of patients showed discordance between the LAVI and LVZ, which are both independent predictors for AF recurrence. A substantial LA volume seems to contribute to early AF recurrence, whereas a high scar burden appears to affect late AF recurrence.

Exploring LGE areas in the atria: Insights from electroanatomical voltage mapping in AF patients

Abstract Introduction Late gadolinium enhancement MRI (LGE MRI) is a common method for the evaluation of the atrial substrate in atrial fibrillation (AF) patients. The extent of LGE is associated with atrial cardiomyopathy and ablation outcomes. However, previous studies have yielded inconsistent results in detecting low voltage areas (LVA) using bipolar electroanatomical mapping (EAM) in LGE regions. Objective Conduct a thorough analysis of the bipolar and unipolar voltage in LGE areas and its relationship with the voltage in non-LGE areas, utilizing high-density (HD) EAM generated by a multipolar HD-mapping catheter. Methods In this study, 20 patients undergoing AF ablation were examined using LGE-MRI. A 3D mesh integrating LGE data was generated. HD-EAM (> 4000 points) was performed in sinus rhythm. The EAM map and MRI mesh underwent manual alignment and registration. Using a nearest neighbor algorithm, EAM points nearest to LGE areas were identified, and the corresponding unipolar and bipolar voltage values, along with LGE voxel intensity, were exported for analysis. Results LGE areas exhibited a median bipolar voltage amplitude of 0.93 mV, median unipolar voltage of 1.73 mV. In contrast, areas without enhancement displayed median bipolar voltage of 2.33 mV, unipolar voltage of 3.58 mV. We observed a variation in voltage amplitudes across the different LGE areas: bipolar voltage ranged from 0.04 to 2.51 mV and unipolar voltage from 0.22 to 3.75 mV. This variation strongly correlated with voxel intensity in LGE areas (correlation coefficient r = -0.86 [p <0.001]). Irrespective of the voltage amplitude in the examined LGE areas, a significant voltage drop was observed, with an average reduction of 54% in bipolar and 51% in unipolar voltages, compared to the amplitudes in non-LGE areas within the same atria. Conclusion Variations in bipolar and unipolar voltage within LGE areas are significantly correlated with local voxel intensity. Despite the inconsistent overlap with the predefined bipolar threshold for LVA, LGE regions exhibit a pronounced and consistent reduction in both bipolar and unipolar voltage compared to non-LGE areas. This pattern suggests notable electrophysiological changes in these areas. These insights underscore the need for further investigation to better understand the implications and mechanisms underlying these alterations in LGE regions.

Role of 3D-electro-anatomical mapping on procedural characteristics and outcomes in pulsed-field ablation for atrial fibrillation

Abstract Introduction While the utilization of dedicated 3D-electro-anatomical mapping (EAM) systems for catheter ablation of atrial fibrillation (AF) is crucial using radiofrequency, its potential benefits in pulsed-field ablation (PFA) remain uncertain. This is of particular interest, since some PFA ablation systems will soon be available with integrated 3D-EAM capabilities. Objectives To compare the procedural characteristics and outcomes of patients undergoing PFA for pulmonary vein isolation (PVI) with mapping and with no mapping. Methods We prospectively enrolled patients undergoing their first PVI at a tertary referral center. In patients undergoing PVI with mapping, a multipolar mapping catheter was used to create voltage maps during sinus rhythm pre- and post-ablation. In the non-mapping group PVI was confirmed by assessing entrance block via the PFA catheter. The first 30 cases with mapping were excluded to account for a potential learning curve. Results A total of 197 consecutive patients were included (age 65 [interquartile range (IQR) 58 – 72] years; indexed left atrial volume 40 [IQR 35 – 44] mL/m2). Among these, 127 patients (64%) underwent PVI with mapping and 70 patients (36%) with no mapping. The median procedure duration, left atrial dwell time and the fluoroscopic time for the mapping vs the non-mapping group were 55 [IQR 45 – 67] min vs. 28 [IQR 23 – 35] min (p < 0.001), 38 [IQR 30 – 49] min vs. 15 [IQR 11 – 21] min (p < 0.001), 11 [IQR 9 – 14] min vs. 8 [IQR 7 – 11] min (p < 0.001), respectively. In the mapping group in 9% (11/127 patients) at least 1 PV was incompletely isolated and required additional applications. Acute PVI success was 100%. There were two complications in the mapping group (one stroke, one coronary artery air embolism) and none were observed in the non-mapping group. The recurrence rate of atrial arrythmias during a median follow-up of 267 [IQR 164 – 419] days was 14% in the mapping group and 17% in the non-mapping group, p = 0.728. Conclusion In conclusion, the use of PFA with no mapping was associated with a significant decrease in procedural characteristics, while AF-recurrence was not significantly different. The routine use of mapping for PFA-PVI may not be needed.Figure 1

Single versus double transseptal puncture for pulmonary vein isolation with radiofrequency catheter ablation for atrial fibrillation - insights from "Go for Zero Fluoroscopy" registry

Abstract Background Transseptal puncture is one of the most challenging steps in catheter ablation of atrial fibrillation (AF) because of the potential risk of complication. While single TSP reduces the puncture-related risk, double TSP simplifies the procedure (immediate signal visualization in pulmonary veins, avoidance of multiple changes of catheters through the single sheath). The purpose of this study was to analyze the impact of single versus double TSP during pulmonary vein isolation (PVI) with radiofrequency (RF) catheter ablation for AF on the fluoroscopy usage and procedure time. Methods Data reported from the international, multicenter prospective „Go For Zero Fluoroscopy Registry" performed in years 2018–2019 were analyzed. Overall 25 European electrophysiology centers from 14 countries and up to 5 operators from each center were enrolled. Only isolated PVI procedures were analyzed. Results A total data of 393 PVI RF procedures were collected from 25 centers. The median dose-area-product (DAP), fluoroscopy time and overall procedure time were: 810 (325 – 1839) cGy*cm2, 8 (4 – 14) minutes and 124 (92 – 168) minutes, respectively. Single TSP was associated with significantly higher DAP: 984 (459 – 1939) vs 667 (227 – 1469) cGy*cm2 (p=0.002), longer fluoroscopy time: 11 (6 – 19) vs 6 (3 – 11) minutes (p<0.001) and longer overall procedure time: 133 (103 – 168) vs 110 (90 – 168) minutes (p=0.003) as compared with double TSP. Single and double TSP group did not differ significantly in regards of general anesthesia usage, circular and multipolar mapping catheter use (p>0.05). However, single TSP was performed by operators with longer EP lab experience: 10 (4 – 15) vs 3 (0 – 10) years (p<0,001). Conclusions Double TSP is related with lower fluoroscopy usage and shorter overall procedure time of pulmonary vein isolation with radiofrequency catheter ablation for atrial fibrillation.

HD grid versus circular mapping catheter for assessment of pulmonary vein (pv) reconnections

Abstract Background Traditionally, circular mapping catheters (CMC) have been considered superior to other designs for mapping pulmonary vein reconnections due to the circular shape of the PV ostium. The grid multipolar catheter produces higher definition maps potentially overcoming the disadvantage of being rectangular. Purpose We assessed the acute procedural results, comparing Grid versus CMC in the setting of PV re-isolation to understand if one was superior to the other. Methods In this multicentre randomised controlled trial, 169 patients (62% male; median age 66 years [22-83) underwent repeat ablation, between July 2021 and March 2023, for recurrent symptomatic atrial arrhythmias. We undertook two LA maps for patients, utilising the Grid and the CMC. Blinded maps were collected with both catheters, followed by randomisation to one map for analysis and ablation. The primary outcome was the radiofrequency time required to isolate the pulmonary veins. Secondary outcomes include LA mapping time and density for both catheters, ability to identify pulmonary vein sleeves and duration of the ablation procedure. Results 126 patients had PV reconnections. 66 patients (64% male; median age 65 years [22-83]) in the Grid arm and 60 patients (68% male; median age 65.5 years [31-83]) in the CMC arm. There was one pericardial effusion and one TIA. There was no significant difference (p=0.202) found in the RF time required to achieve PV isolation in both Grid (mean RF time 200 ± 232 secs) vs CMC (mean RF time 169 ± 298 secs) arms. There was no significant difference (p=0.407) found between LA mapping time for the CMC (mean 1047 ± 454 seconds) and the Grid (Median 1080 ± 440 seconds). There was no significant difference (p=0.411) found in the total procedure time for the CMC (mean 122.7 minutes) and the HD grid (130 minutes). There were significantly more (p<0.001) PV mapping points identified with the grid (mean 354±213 points) than the CMC (mean 234±154 points) arm. There was no significant difference in PV sleeve reconnections found (p=0.106) between the grid (120 PV sleeve reconnections with a mean 1.4±0.71 reconnections) and the CMC (98 PV sleeve reconnections with a mean 1.52±0.72 reconnections). Both maps were analysed to assess reconnections on opposing catheter arms. The grid identified 20 PV sleeve reconnections not visible on the CMC, whilst 9 were visible on the CMC and not the grid. Conclusion There was no significant difference found in RF time, mapping time and overall procedure time. The Grid identified more reconnections not seen with the CMC and had an overall improved mapping density suggesting that this configuration could be superior for LA mapping.

Accuracy of a non-invasive mapping system for the localisation of re-entrant VT site of origin and its relationship to myocardial scar on cross-sectional imaging

Abstract Introduction View in ventricular onset (VIVO) is a non-invasive mapping system used for localising the site of earliest activation in ventricular arrhythmia, utilising a mathematical algorithm, patient specific cardiac model (constructed using cross-sectional imaging data), 3D images of the patient’s torso (for localising surface electrodes), and a 12-lead electrocardiogram (ECG).(1, 2) Several publications have examined its role in the localisation of premature ventricular contractions (PVCs), and a 5 patient case series assessed its role in scar related re-entrant VT.(1-4) However, its validity in a larger cohort and of the relationship to the relevant myocardial scar has not been investigated. Objective Assess the accuracy of the VIVO mapping system in localising the VT-SoO for patients with scar related re-entrant VT and its relationship to the relevant myocardial scar on cross-sectional imaging. Methods 20 patients with structural heart disease (18 ischaemic cardiomyopathy (ICM), 1 dilated cardiomyopathy (DCM), 1 hypertrophic cardiomyopathy (HCM)) (Male n=18, 63±14 years) and recent cross-sectional cardiac imaging, were recruited over a 16-month period (table 1). All patients had a clinical indication for VT ablation and were on optimal medical therapy, 19 had an implantable cardiac defibrillator. Invasive electro-anatomical mapping (EAM) was performed with the Advisor HD Grid multipolar catheter and maps were generated using Omnipolar electrograms (EGMs). The VT-SoO was identified using an activation- or pace-map by an experienced operator and the location defined using the American heart association’s 17 segment model of the left ventricle during the procedure.(5) VIVO maps were reviewed by a second independent operator and a segment allocated, scar segments were obtained from cross-sectional imaging. A "complete match" was defined as exact segment concordance between allocated segments, "partial match" as adjacent segments, and "no match" if it does not satisfy either of those requirements. Results Mean left ventricular ejection fraction was 35.5 ± 10.6%. Mean procedure time was 242 ± 70 minutes, with a mean ablation time of 20 ± 11.1 minutes. A total of 32 re-entrant VTs were mapped. The VT exit site was identified in all cases (11 activation-map; 21 pace-map). A complete match between the EAM and VIVO map was seen in 75% of VTs and partial match in a further 15% (table 2). The VT-SoO was located withing the myocardial scar (or directly adjacent to is) in 83% of accurately mapped VTs. Procedural success (defined as freedom from device treated episodes) was seen in 90% of patients at mean follow up of 7.3 ± 4.7 months. Conclusion VIVO non-invasive mapping system was able to accurately map the VT-SoO in scar dependent VT, and identify the relevant myocardial scar as seen on cross sectional imaging. Further research assessing its ability to accurately identify relevant ablation targets is ongoing.

Predictability of indicators in local activation time mapping of ablation success for premature ventricular contractions

AbstractIntroductionDifferences in predictability of ablation success for premature ventricular contractions (PVCs) between earliest isochronal map area (EIA), local activation time (LAT) differences on unipolar and bipolar electrograms (⊿LATBi‐Uni), LAT prematurity on bipolar electrograms (LATBi), and unipolar morphology of QS or Q pattern remain unclear. We verified multiple statistical predictabilities of those indicators of ablation success on mapped cardiac surface.MethodsThirty‐five patients with multiple PVCs underwent catheter ablation after LAT mapping using multipolar mapping catheters with unipolar‐based annotation. Patients were divided into success and failure groups based on ablation success on mapped cardiac surfaces. Discrimination ability, reclassification table, calibration plots, and decision curve analysis of 10 ms EIA (EIA10ms), ⊿LATBi‐Uni, and LATBi were validated. Unipolar morphology was compared between success and failure groups.ResultsRight ventricular outflow tract, aortic cusp, and left ventricle were mapped in 17, 10, and 8 patients, respectively. In 14/35 (40%) patients, successful ablation was performed on mapped cardiac surfaces. Area under the curve of receiver‐operating characteristic curve of EIA10ms, ⊿LATBi‐Uni, and LATBi were 0.874, 0.801, and 0.650, respectively (EIA10ms vs. LATBi, p =.014; ⊿LATBi‐Uni vs. LATBi, p =.278; EIA10ms vs. ⊿LATBi‐Uni, p =.464). EIA10ms and ⊿LATBi‐Uni demonstrated better predictability, calibration, and clinical utility on reclassification table, calibration plots, and decision curve analysis than LATBi. Unipolar morphology of QS or Q pattern did not correlate with ablation success (p =.518).ConclusionEIA10ms and ⊿LATBi‐Uni more accurately predict ablation success for PVCs on mapped cardiac surfaces than LATBi and unipolar morphology.

Prediction of major intravascular hemolysis during pulsed electric field ablation of atrial fibrillation using a pentaspline catheter.

Pulsed electric field (PEF) has emerged as a promising energy source for catheter ablation of atrial fibrillation (AF). However, data regarding the in-vivo effect of PEF energy on erythrocytes during AF ablation procedures are scarce. This study aimed to quantify the impact of PEF energy on erythrocyte damage during AF ablation by assessing specific hemolytic biomarkers. A total of 60 patients (age: 68 years, males: 72%, serum creatinine: 91 µmol/L) with AF underwent catheter ablation of AF using PEF energy delivered by a multipolar pentaspline Farawave catheter (Farapulse, Boston Scientific, Inc.). Ablation beyond pulmonary vein isolation was performed at the operator's discretion. Peripheral venous blood was sampled for assessing the plasma levels of free hemoglobin (fHb), direct (conjugated) bilirubin, lactate dehydrogenase (LDH), and creatinine before, immediately after the ablation, and on the next day. Following the PEF ablation with duration of [median (interquartile range)] 75 (58, 95) min, with 74 (52, 92) applications and PVI only in 27% of patients, fHb, LDH, and direct bilirubin significantly increased, from 40 (18, 65) to 493 (327, 848) mg/L, from 3.1 (2.6, 3.6) to 6.8 (5.0, 7.9) µkat/L, and from 12 (9, 17) to 28 (16, 44) µmol/L, respectively (all p < .0001). A strong linear correlation was found between the peak fHb and the number of PEF applications (R = 0.81, p < .001). The major hemolysis (defined as fHb >500 mg/L) was predicted by the number of PEF applications with the corresponding area under the receiver operating characteristic curve of 0.934. The optimum cut-off value of >74 PEF applications predicted the major hemolysis with 89% sensitivity and 87% specificity. Catheter ablation of AF using PEF energy delivered from a pentaspline catheter is associated with significant intravascular hemolysis. More than 74 PEF applications frequently resulted in major hemolysis. However, the critical amount of PEF energy that may cause kidney injury in susceptible patients remains to be investigated.

Pulsed-field- vs. cryoballoon-based pulmonary vein isolation: lessons from repeat procedures.

Pulsed-field ablation (PFA) is an emerging technology to perform pulmonary vein isolation (PVI). Initial data demonstrated high safety and efficacy. Data on long-term PVI durability and reconduction patterns in comparison to established energy sources for PVI are scarce. We compare findings in repeat ablation procedures after a first PFA to findings in repeat ablation procedures after a first cryoballoon ablation (CBA) based PVI. A total of 550 consecutively enrolled patients underwent PFA or CBA index PVI. Repeat ablations in patients with symptomatic atrial arrhythmia recurrences were analysed. A total of 22/191 (12%) patients after index PFA-PVI and 44/359 (12%) after CBA-PVI underwent repeat ablation. Reconduction of any pulmonary vein (PV) was detected by multipolar spiral mapping catheter at each PV with careful evaluation of PV potentials and by 3D-mapping in 16/22 patients (73%) after PFA-PVI and in 33/44 (75%) after CBA-PVI (P = 1.000). Of 82 initially isolated PVs after PFA-PVI, 31 (38%) were reconducting; of 169 isolated PVs after CBA-PVI, 63 (37%) were reconducting (P = 0.936). Clinical atrial tachycardia occurred similarly in patients after PFA (5/22; 23%) and CBA (7/44; 16%; P = 0.515). Roof lines were set more often after PFA- (8/22; 36%) compared with CBA-PVI (5/44; 11%; P = 0.023). Repeat procedure duration [PFA: 87 (76, 123) min; CBA: 93 (75, 128) min; P = 0.446] was similar and fluoroscopy time [PFA: 11 (9, 14) min; CBA: 11 (8, 14) min; P = 0.739] equal between groups at repeat ablation. During repeat ablation after previous PFA- or CBA-based PVI, electrical PV-reconduction rates and patterns were similar.

Characterization of patients with extensive left atrial myopathy referred for atrial fibrillation ablation: incidence, predictors, and outcomes.

Although atrial fibrosis has a relevant impact on ablation success rate, experimental studies have reported that extensive fibrosis may be accompanied by a reduced burden secondary to a prominent depression of atrial excitability. We aimed to identify clinical and echocardiographic factors associated with extensive left atrial myopathy (ELAM), to analyze the predictive ability of established scores (AF score, APPLE, and DR-FLASH) and assess outcomes in terms of AF recurrence, left atrial flutter, and post-procedural heart failure admissions. A total of 950 consecutive patients undergoing the first AF ablation were included. A 3D electroanatomical mapping system (CARTO3, Biosense Webster) was created using a multipolar mapping catheter (PentaRay, Biosense Webster). ELAM was defined as ≥ 50% low voltage area. A subanalysis with four groups was also created (< 10%; 10-20%; 10-20%; and > 30%). Logistic regressions, Cox proportional hazards models, and log-rank test were used to test the predictors independently associated with the presence of ELAM and AF recurrence. The model was prospectively validated in a cohort of 150 patients obtaining an excellent ability for prediction AUC 0.90 (CI 95% 0.84-0.96). Overall, 78 (8.42%) presented ELAM. Age, female sex, persistent AF, first-degree AV block, and E/e' were significant predictors. The model incorporating these factors outperformed the existing scores (AUC = 0.87). During a mean follow-up of 20months (IQR 9 to 36), patients with ELAM presented a higher rate of AF recurrence (42.02% vs 26.01%, p = 0.030), left atrial flutter (26.03% vs 8.02%, p < 0.001), and post-procedural heart failure admissions (12.01% vs 0.61%, p < 0.001) than non-ELAM patients. This study reveals the incidence and clinical factors associated with ELAM in AF, highlighting age, female, persistent AF, first-degree AV block, and E/e'. Importantly, the presence of ELAM is associated with poorer outcomes in terms of recurrence and HF admission.

Impact of magnetic data collection prior to electroanatomic model creation on acute outcomes in de novo AF procedures

Abstract Background As ablation and electroanatomical mapping technology evolve, workflows change to maximize the impact on procedural efficacy, safety, and efficiency. In a magnetic-primary navigation mode, optimization of the magnetic-impedance field links (VoXels) must be considered to provide accurate environments for anatomic modeling, mapping, and lesion placement. To achieve this accuracy and optimize speed of data collection, many operators have adopted the strategy of collecting VoXels using an ablation catheter prior to introduction of a multipolar mapping catheter. However, the impact of this workflow on procedural metrics has not yet been quantified in a multicenter, international cohort. Objective Assess the impact of optimizing the magnetic navigation field using an ablation catheter prior to collecting left atrial (LA) data using a high-density diagnostic tool on acute outcomes in de novo atrial fibrillation (AF) ablation procedures. Methods Acute observational data from 199 de novo pulmonary vein isolation (PVI) cases was prospectively collected from 56 operators at 42 centers in Europe, the US, and Australia. Procedural metrics, modeling workflow, ablation technology used, and acute outcomes were collected. Results Of 199 de novo AF (62.3% PAF) ablation procedures, VoXels were collected with an ablation catheter prior to LA map collection with a multipolar catheter in 65/199 (32.7%) cases; the remainder collected with multipolar catheter first. An irrigated, contact force sensing RF ablation catheter was used in all procedures. Mean procedure duration was similar in procedures in which VoXels were collected prior to map collection (VC) compared to those that did not (nVC) (107.0±46.8 min and 115.4±59.2 min, respectively (p=0.28)). Mean fluoroscopy time was significantly reduced in VC cases compared to nVC cases (3.0±4.5 min and 5.3±5.6 min, respectively (p=0.002)). Total RF duration was significantly reduced in VC cases compared to nVC cases (904±444s and 1063±632s, respectively (p=0.04)). There was also a significant reduction in fluid delivered through the ablation catheter in VC cases, 369±159mL, compared to nVC cases, 520±243mL (p&amp;lt;0.001). Acute success rates were similar between groups: 98.5% for VC cases and 99.2% for nVC cases (p=0.64). Conclusion In this international cohort, cases where VoXels were collected prior to map and model collection had significantly reduced fluoroscopy times, RF durations, and fluid volumes delivered through the ablation catheter, potentially as a result of improved model quality. Despite the introduction of an additional step to the workflow, there was a trend toward shorter procedures when VoXels were collected prior to map and model collection, although it did not achieve statistical significance. Better quantification of the impact of this workflow on model quality, along with analysis of long-term patient outcomes, is warranted.Procedure Duration Comparison_VC vs. nVCFluoroscopy Comparison_VC vs. nVC

First clinical experience using a novel 8-spline ultra high-resolution mapping catheter to guide atrial fibrillation ablation

Abstract Background Multielectrode mapping catheters improve the detection of scarred and fibrotic tissue in patients with atrial fibrillation (AF) Recently, a novel multispline mapping catheter with 48 closely spaced microelectrodes has been introduced enabling fast high-resolution electroanatomical mapping. Objective This study sought to report our initial clinical experience with the novel Octaray catheter in patients with AF undergoing index ablation and to compare its impact on mapping and ablation with the 5-spline Pentaray catheter. Methods The study included consecutive patients who underwent index AF ablation using a multipolar mapping catheter and very high-power-short-duration guided ablation (Q4U-AF workflow; QDot; Qmode+; Biosense Webster) in conjunction with a visualized sheath (Vizigo; Biosense Webster). Arrhythmia recurrence was defined as any atrial fibrillation (AF)/ atrial tachycardia (AT) episode lasting &amp;gt; 30 s after a blanking period of 3 months. Results A total number of 183 patients undergoing AF ablation using the Octaray and QDot catheter were compared to a group of 166 matched patients who underwent ablation using Pentary and QDot. Utilization of the Octaray catheter resulted in an increased identification of areas with bipolar low-voltage representing fibrosis/scar or atrial cardiomyopathy (mean amount of left atrial bipolar low-voltage: Octaray 31% vs. Pentaray 18%; p= 0.03) and a higher rate of first-pass isolation (FPI) for the left-sided pulmonary veins (Octaray: FPI rate 73% vs. FPI rate 64% for Pentaray). A significantly higher number of mapping points was acquired using the novel 8-spline mapping catheter (right atrium: Octaray 1936 points vs. Pentaray 903 points; p &amp;lt; 0.001 left atrium: Octaray 5337 points vs. Pentaray 2385 points; p &amp;lt; 0.001). Procedural parameter, radiation time/dosage and acute procedural success were comparable between the two groups. During a mean follow-up of 12 months, the overall procedural success was 86 in the Octaray group vs. 84% in the control group (p=0.9). Conclusion The utilization of the novel Octaray mapping catheter resulted in an improved detection of atrial fibrosis and scar as well as a higher rate of first-pass pulmonary vein isolation. Figure: Institutional Q4U-AF-workflow using a multipolar mapping catheter, the QDot ablation catheter and a visualized sheath. High resolution mapping using the Octaray (A+B) and PentaRay catheter (C+D).

Pulsed electric field ablation for perimitral flutter - retrospective comparison of anterior vs lateral mitral block strategy

Abstract Introduction Catheter ablation of atrial fibrillation has become a standard of care for symptomatic patients. Patients with persistent atrial fibrillation might require additional substrate modification on top of pulmonary vein isolation. In case of spontaneous or inducible perimitral flutter, RF ablation to achieve anterior or lateral mitral block is challenging. A pulsed electric field (PEF) is a novel energy source that enables the rapid and safe creation of larger lesions. Purpose A retrospective study aimed to compare the safety and early outcome data of either anterior or lateral mitral block strategy performed by PEF using a pentaspline multipolar ablation catheter. Methods The population consists of 67 patients (23 women, age: 68 ± 8 years) with either spontaneous or inducible perimitral flutter. Fifty-five percent of patients had previous ablation of atrial fibrillation using radiofrequency energy (2.0 ± 1.2 procedures/patient). Using a pentaspline multipolar catheter, all patients underwent isolation (or reisolation) of pulmonary veins and posterior wall. The same catheter was used for the treatment of perimitral flutter. Creating either anterior (ANTERIOR group) or lateral (LATERAL group) mitral block was selected at the discretion of the operator. Results A total of 37 and 30 patients were treated in the ANTERIOR and LATERAL groups, respectively. The perimitral flutter was terminated in all cases. However, complete and persistent block across the ablated region was more likely achieved in the ANTERIOR vs LATERAL group (92 vs 73%, p=0.04). There was one tamponade in the ANTERIOR group. A clinically relevant spasm of the coronary artery was not observed in any patient. At 3-month follow-up, non-significantly more patients were in sinus rhythm in the ANTERIOR vs LATERAL group (81% vs 63%, p=0.1). Conclusion Creating both anterior and lateral mitral block for the treatment of perimitral flutter is feasible and safe using a pentaspline multipolar catheter and PEF. Achievement of the anterior mitral block is more likely. Whether this will impact the long-term outcome remains to be determined.

Single-centre experience with an electrogram-based artificial intelligence software system to identify drivers in pulsed field ablation of persistent atrial fibrillation

Abstract Background Ablation of persistent atrial fibrillation (AF) beyond pulmonary vein isolation (PVI) remains challenging, despite increasing numbers of eligible patients. Previous studies suggest a possible role for non-PVI lesions targeting atrial drivers, but their identification can be difficult and subject to inter-operator variability. Purpose We investigated feasibility for an electrogram-based artificial intelligence software system to assist in the identification of left or right atrial dispersion sites as ablation targets for persistent AF using the penta-spline multi-electrode pulsed-field ablation (PFA) catheter, a recent technique which is more conventionally employed for PVI. Methods This is a single-centre retrospective descriptive study of a cohort of patients with persistent AF, who underwent their first-time ablation from May to November 2023 using the Farawave PFA catheter (Boston Scientific) and the VX1 system (Volta Medical). This system relies on off-line pre-training of multiparametric machine learning algorithms on a database of annotated AF intracardiac electrograms. It connects to cardiac electrophysiology recording systems via a custom data cable to receive analogue data and digitize them through an integrated converter. Its algorithms analyse signals in the cardiac chamber of interest to adjudicate the local presence or absence of dispersion and provides relevant visual cues to operators in order to target energy delivery. Results We identified 16 patients who underwent PFA for persistent AF (long-standing in 5/16, 31.3%), including PVI and further ablation guided by VX1. See table 1 for baseline population characteristics and table 2 for procedural characteristics. All underwent ablation with uninterrupted anticoagulation, general anaesthesia, use of the Rhythmia electroanatomic mapping system and its Orion mapping catheter (Boston Scientific) to feed signals into the VX1 system. VX1-guided electrogram localization and ablation mostly targeted the anterior region of the left atrium (16 segments), followed by its septal region (6 segments) and its lateral region (4 segments); the median number of applications per procedure was 88 [IQR 68-108], including a median of 76 [61-85] in the left atrium and 12 [0-15] applications in the right atrium. The median procedure duration was 123 [114-137] minutes; the median fluoroscopy time was 32 [26-40] minutes and the median radiation dose was 12.5 Gy∙cm2 [10.0-25.8]. Sinus rhythm was restored either during ablation or by electrical cardioversion (see Table 2). Two complications occurred one femoral arteriovenous fistula requiring stenting and one tamponade requiring drainage. At a three-month follow-up, 87.5% did not present AF recurrences. Conclusion Real-time detection and annotation of electrograms to track dispersion using AI-assisted technology to support PFA with a multipolar catheter is feasible. The interest of the approach should be validated by further studies.Table 1.Table 2.

Localization of ganglionated plexi by high density mapping: an atropine-response analysis

Abstract Introduction Growing interest has emerged around cardiac autonomic nervous system driven by ablation approaches for the treatment of neurally-mediated syncope (NMS). Ganglionated-plexi (GPs) located in the epicardial fat pads are the main target of ablative therapies, but little is known about the finest method to track their location from the endocardium. Most current techniques rely on empirical research of signal fragmentation and/or vagal response at anatomical landmarks. A poor accuracy in targeting GPs may lead to the risk of incomplete or over-extensive ablation. Purpose We analyzed the atrial electrograms (EGMs) in healty subjects and their response to atropine to describe physiological fragmentation and the relationship with vagal output. Methods Study partecipants were selected from young patients without structural heart desease who underwent electrophysiological study (EPS) for standard indications. High-density mapping of right atrium was performed before and after administration of 2 mg atropine at the end of the planned procedure. Offline analyses were performed comparing the two maps of each patient focusing on the fragmentation of the atrial EGMs. Results The study cohort comprised 10 patients (mean age of 39±11 years, 6 males). The indication for EPS was: supraventricular tachycardia (SVT) ablation in 9 patients, syncope in 1 patient. High density three-dimensional electro-anatomic maps (EAM) were all obtained with a multipolar catheter during sinus rhythm (number of points: 8794±937 in basal maps and 9007±1296 after atropine, p=0,87). The response to atropine was documented by an increase in heart rate (mean increase 59 ± 19% of basal cycle length). All basal maps showed a similar pattern of fragmentation in the posterior-septal wall reflecting the anatomical distribution of right GPs. In particular, three main stations were identified in the supero-, mid- and infero-posterior regions. Fragmentation of EGMs was found to progress from the edge to the core of each area. After administration of atropine, a reduction in fractionated area was observed in all patients. Filtering the maps according to a cut-off of fragmentation ≥ 6 peaks allowed identification of the nucleus with the highest degree of variation after atropine injection (mean basal area = 0,89 ± 0,81 cm2 ; mean atropine area = 0,44 ± 0,56 cm2 p&amp;lt;0,001). Conclusion Fragmentation of atrial electrograms is a dynamic property related to vagal output. High density mapping with a high pass filter of 6 peaks allows to identify the smallest vagal sensitive area in the anatomical stations of the GPs.

Clinical validation of a novel digital twin framework for ventricular functional substrate simulation in post-infarction patients

Abstract Background Catheter ablation is a cornerstone treatment for scar related post-infarction ventricular arrhythmias. Functional substrate driven ablation strategies guided by local activation time (LAT) mapping have been proven as efficient and effective approaches, especially when dealing with large scar areas. In-silico electrophysiological modeling is emerging as a potential tool for procedural planning and guidance. Purpose To clinically validate the feasibility, diagnostic performance, and accuracy of a novel late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) based digital twin framework for simulated LAT map generation in post-infarction patients and their integration with CARTO3 EAM suite. Methods Five ischemic subjects who underwent CMR-aided scar-related ventricular tachycardia ablation at our referral center were retrospectively enrolled. Their CMR derived 3D pixel-signal-intensity (PSI) maps generated with ADAS3D were processed with novel in-house software to obtain patient-specific ventricular geometry, tissue characterization, and to generate a model of Purkinje system and myocyte fiber orientation. According to local normalized pixel intensity (NPI) values, myocardial regions were marked as healthy, scar, or border-zone. Electrophysiological properties of border-zone (BZ) were modulated according to local NPI. Continuous and 8-steps isochronal endo-epicardial LAT maps were generated and imported in CARTO3 system, aligned with electroanatomical mapping (EAM), and compared at an ASE 17-segments level, in terms of sensitivity, specificity, predictive values, and accuracy to actual high-density LAT maps obtained with a multipolar catheter. Deceleration Zones (DZ) were defined as previously described (&amp;gt;3 isochrones within 1 cm radius). Results A total of 85 ASE segments (34 epicardial) were analyzed. 24 EAM segments (28%) held DZs, 40 (47%) segments harbored bipolar scar or BZ. Thirty-seven (44%) CMR segments held scar core/BZ. Thirty (35%) digital model segments harbored DZs. Generated LAT maps were successfully imported and aligned with CARTO3 EAM suite for validation. In terms of DZ localization prediction, our LAT model showed 83% sensitivity (95% CI 63%-95%), 90% specificity (95% CI 80%-96%), 77% positive predictive value (PPV) (95% CI 56%-91%), 93% negative predictive value (NPV) (95% CI 83%-98%), 88% accuracy (95% CI 79%-94%). Conclusion Our newly developed framework for LGE-CMR derived functional substrate simulation in post-infarction patients holds high sensitivity, specificity, predictive values, and accuracy for DZ localization. Further validation, with a larger sample size, is required for evaluating potential implications in clinical practice.

Predictors of low-voltage areas in the left atrium in patients with atrial fibrillation

Abstract Background Low-voltage areas (LVA) in the left atrium (LA) electroanatomical map are potent predictors of the efficacy of atrial fibrillation (AF) ablation. Clinical factors predicting the presence of LVA have moderate accuracy. The aim of the study was to find clinical and echocardiographic factors predicting the presence of LVA in patients undergoing AF ablation. Methods Consecutive unselected patients undergoing AF ablation were included in the retrospective analysis. All patients underwent transthoracic (including LA strains) and transesophageal echocardiography, pulmonary vein isolation and LA electroanatomical mapping using multipolar catheter. LVA were defined as an area greater than 2cm2 with a voltage below 0.5mV (or 0.3mV when measured during AF). Results A total of 432 patients were included in the analysis, 107 (24.8%) had LVA. The mean age of the study population was 62.8 years, 185 patients had nonparoxysmal AF (42.8%). In the univariate logistic regression analysis numerous clinical parameters (age, female sex, presence of heart failure, diabetes, coronary artery disease, AF during examination), echocardiographic parameters (LA reservoir strain - LASr, LA emptying fraction, LA volume index, E/e’, LA appendage velocity - LAAV) and mean LA pressure (measured invasively) were significant predictors of the presence of LVA. In the multivariate logistic regression analysis age (HR 1.11 per 1 year increase, p&amp;lt;0.001), LASr (HR 0.89 per 1% increase, p=0.014) and LAAV (HR 0.93 per 1cm/s increase, p&amp;lt;0.001) were significant predictors of the presence of LVA. In receiver-operator curve (ROC) analysis LASr and LAAV were potent predictors of LVA in patients tested on sinus rhythm (AUC 0.86 and 0.87 respectively), while they had moderate predictive value in patients tested on AF (LASr AUC 0.67, LAAV AUC 0.77). Conclusions Age, LASr, and LAAV were significant predictors of LVA in patients undergoing AF ablation. The predictive value of LASr and LAAV was better in patients examined during sinus rhythm than in patients examined during AF.

Atrial pace mapping using intracardiac pattern matching: feasibility and accuracy

Abstract Introduction Pace mapping of atrial arrhythmia is a method to localize the origin of usually focal arrhythmias that are unstable or not persisting during EP-study and, therefore not eligible for LAT-Mapping. The technique applies pattern matching of p-waves from surface-electrocardiogram (sEKG) as well as intracardiac signals during atrial tachycardia and pacing from the site of suspected origin. The CARTO® 3 system Version 7.2 applies an automated algorithm for intracardiac pace mapping (ICPM) using the unipolar signal of the reference electrode, usually located in the coronary sinus. Methods We examined 12 consecutive patients undergoing RF pulmonary vein isolation (PVI). We performed local pacing at the anterior and posterior wall of the left atrium (LA) and the posterior and lateral wall of the right atrium (RA). The first pacing point was defined as the reference pacing site (RPS). The ICPM algorithm was applied to calculate the similarity of the IC pattern of the RPS to the IC pattern across various distances. The maps, including mesh, point locations and IC pattern similarity of each point, were exported for further analysis in the Python environment. The areas were calculated for the 5% similarity strata. Results The study assessed areas with a 95% or higher pattern similarity in different atrial regions, revealing notable differences in pattern similarity. The median area of pattern similarity was 1.48 cm² (IQR: 0.76 - 2.01 cm²) in the LA posterior, 0.62 cm² (IQR: 0.15 - 1.06 cm²) in the LA anterior, 0.60 cm² (IQR: 0.38 - 1.19 cm²) in the RA posterior, and 5.68 cm² (IQR: 2.89 - 11.1 cm²) in the RA lateral wall. Significant differences were found between the posterior and anterior walls of the LA and the RA lateral wall, as well as between the RA posterior and RA lateral wall, indicating variability in intracardiac pattern matching accuracy. Patterns below 2 cm² are acceptable for catheter ablation. An outlier was noted in the RA posterior region. Conclusion The intracardiac pattern matching for atrial arrhythmias employing the CARTO-ICPM algorithm is feasible with acceptable accuracy except for the lateral regions of the right atrium. This might be explained by the larger distance to the referent catheter in the coronary sinus and the preferred conduction direction in the crista terminalis. Enhancing localization accuracy may necessitate the adjunctive use of surface ECG-pace mapping or the deployment of an additional multipolar intracardiac reference catheter in the lateral RA.A: IC Pattern, B: Box plots similarity

High efficacy and safety of endocardial pulsed electrical field ablation via contact force-controlled catheters for mitral isthmus ablation

Abstract Background A new technology of a pulsed field generator enables established contact force-controlled radiofrequency (RF) catheters to apply point by point monopolar pulsed electrical field (PEF) energy for linear lesions in atrial fibrillation (AF) ablation. Purpose We evaluated this novel monopolar PEF ablation technique for creating lateral mitral isthmus ablation lines in case of perimitral flutter or complex AF patients non responder to pulmonary vein isolation (PVI). Methods Patients (n=44, age 65±11 years) referred for ablation/re-ablation of AF with spontaneous or inducible perimitral atrial flutter (n=34, 77%) or persistent AF and severe enlarged atrium (n=7) or de novo longstanding persistent AF (n=3) without signs of atrial fibrosis were included in our patient cohort for lateral mitral isthmus ablation with PEF applications. After 3D high density voltage mapping of the left atrium with multipolar microelectrode catheters, and confirmation/completion of PVI, an endocardial lateral mitral isthmus line was performed. Using contact force sensing catheter, 25A PEF energy pulses were applied targeting a minimum of 10g contact force and an interlesion distance ≤5mm. Before PEF application 0.2 mg nitroglycerin was intravenously injected. If the inferolateral mitral isthmus line to the left inferior pulmonary vein could not be blocked, a more superior lateral line to the left superior pulmonary vein was performed. If the mitral isthmus could not be blocked by endocardial PEF application or conduction recurred after adenosine injection an additional epicardial ablation via RF application in the coronary sinus was performed. Results Exclusively endocardial PEF application blocked the lateral mitral line in 37 out of 42 cases (88%) with 23±14 PEF applications. After an unsuccessful inferior lateral mitral line, in 34% of cases a second superior lateral mitral line have to be performed. Only in five cases additional epicardial RF applications via coronary sinus were necessary to complete the mitral isthmus block. Block time between superior lateral mitral anulus and infero lateral coronary sinus was 196±48 ms. One pericardial tamponade which could be successfully drained, and no other serious complication occurred throughout all procedures (no ST segment elevation, no tamponade requiring surgery, no cerebrovascular event). Limited follow-up will be available at the time of presentation. Conclusion Blockade of left atrial mitral isthmus line with PEF application via contact force-sensing catheters for ablation of complex atrial fibrillation patients is very efficient and safe. Especially the high efficacy of exclusively endocardial PEF application for creation of a lateral mitral isthmus block in most patients is very promising. However, the long term permanence of the linear lines have to be awaited.

Posterior wall isolation with pulsed field ablation or radiofrequency ablation with vein of marshall ethanol ablation for the treatment of atrial fibrillation

Abstract Background In patients undergoing repeat catheter ablation for atrial fibrillation (AF) two ablation strategies beyond pulmonary vein isolation (PVI) have recently gained increased interest: posterior wall isolation (PWI) using pulsed field ablation (PFA) and Vein of Marshall (VoM) ethanol ablation combined with radiofrequency energy ablation (RFA). However, a direct comparison is lacking. Purpose To compare prospectively enrolled patients undergoing repeat catheter ablation for persistent AF using PVI and PWI with PFA (PFA group) vs. PVI and VoM ethanol ablation using RFA (VoM group) regarding procedural characteristics, safety, myocardial injury and outcomes. Methods Patients undergoing redo PFA-PVI with PWI and VoM ethanol ablation with RFA were included. Isolation and bidirectional block were checked using a multipolar mapping catheter. High-sensitivity cardiac troponin T (hs-cTnT) was measured after 24h of ablation. Results A total of 84 patients were included (age 69 [interquartile range (IQR) 63-75] years; ejection fraction 56% [IQR 48-60%]; left atrial size 42 [IQR 37-47] mm), baseline characteristics did not differ significantly between groups. Of these, 54 patients (64%) were in the PFA group and 30 (36%) in the VoM group. The procedure duration (65 [IQR 56-73] minutes vs 116 [IQR 103-142] minutes; p &amp;lt; .001) and fluoroscopic times (11 [IQR 8–14] minutes vs 14 [IQR 12-19] minutes; p &amp;lt; .001) were significantly shorter for the PFA group than for the VoM group. No major complications were observed except for a probable allergic reaction in the VoM group and a transient AV-block in the PFA group. High-sensitivity cardiac troponin levels post ablation were similar between the PFA group and the VoM group with 886 [IQR 627–1260] ng/L and 793 [IQR 543-1199] ng/L, p=0.28, respectively. During follow-up (median duration 230 [IQR 117-370] days), AF recurrence was observed in 15% in the PFA group and in 40% in the VOM group (p ≤ 0.01). Conclusion In patients undergoing repeat catheter ablation for AF, PVI and PWI using PFA is associated with shorter procedure and fluoroscopic times, similar high-sensitivity cardiac troponin levels and a reduced recurrence rate compared to PVI using RFA with additional VoM ethanol ablation.Central Illustration