High-density Activation Mapping Research Articles

Atrial Topology for a Unified Understanding of Typical and Atypical Flutter.

Macroreentry stands as the predominant mechanism of typical and atypical flutter. Despite advances in mapping, many aspects of macroreentrant atrial tachycardia remain unsolved. In this translational study, we applied principles of topology to understand the activation patterns, entrainment characteristics, and ablation responses in a large clinical macroreentrant atrial tachycardia database. Because the atrium can be topologically seen as a closed sphere with holes, we used a computational fixed spherical mesh model with a finite number of holes to induce and analyze macroreentrant atrial tachycardia. The ensuing insights were used to interpret high-density activation maps, postpacing interval-tachycardia cycle length values (difference between postpacing interval and tachycardia cycle length), and ablation response in 131 cases of typical and atypical flutter (n=106 left atrium, n=25 right atrium). Modeling of macroreentrant atrial tachycardia revealed that reentry on closed surfaces consistently manifests itself as paired rotation and that an odd number of critical boundaries is mathematically impossible. Together with mathematical confirmation by the index theorem, this led to a unifying construct that could explain the number of loops, difference between postpacing interval and tachycardia cycle length values, and ablation outcomes (termination, no change, or prolongation in tachycardia cycle length) in all 131 cases. Combining topology with the index theorem offers a novel and cohesive framework for understanding and managing typical and atypical flutter.

Prevalance of incessant form of atrial fibrillation by superior vena cava (svc) firing:simplified svc and sinus node mapping(sss map) to avoid sinus node injury

Abstract Background The superior vena cava (SVC) is known as a major source of atrial fibrillation(AF), non-pulmonary vein AF foci (NPVAF). In some cases, an incessant form of AF (iAF) by SVC firing prevents obtaining the sinus node location, and anatomical SVC isolation has a risk of sinus node injury (SNI). Objective This study was aimed to explore the frequency of iAF by SVC firing and the efficacy of the simplified mapping strategy to avoid SNI. Methods Consecutive AF ablation procedures in the 3 centers were retrospectively investigated including the NPVAF prevalence. Simplified SVC/SN mapping (SSS-map: Obtaining the top-end of the SVC potential and >4points with 5-10mm spacing in the upper lateral side of the right atria (RA) for roughly locating the earliest activation site in sinus rhythm) was performed before PV isolation in the last 138 patients. In case of the initial rhythm at the procedure was atrial fibrillation, cardioversion was performed for obtaining the SSS-map. In the cases in which the high-density mapping catheters were available, the high-density activation maps of the RA in sinus rhythm were obtained to investigate the dislocation of the earliest activation site of the SSS map from the SN location. When SVC isolation was required due to iAF, SVC isolation line was designed based on the location of the top-end of the SVC potential during AF and ablative linear lesions were created to keep the distance of 5-10 mm above the second earliest activation site. Results A total of 1160 procedures in 1089 patients (male: 736[63.4%], age: 69.9, paroxysmal AF: 544[49.9%], first session: 997[85.9%]) was investigated. Prevalence of NPVAF was revealed in 160 of the all procedures (13.7%) (the SVC: 64, the posterior wall of the left atria: 24, the coronary sinus: 19, and others: 53). 16 of 160 NPVAFs (10.0%) developed to iAF by SVC firing. The SSS-map was successfully obtained in all of the last 138 patients (Initial rhythm at the procedure: AF 43.7%, Mapping time: 1.3±0.6 min, number of obtained points: 8.4±1.3). In 21 patients in which the high-density RA map was obtained, the SN dislocation distance was 5.1±2.2mm between the SSS map and the high-density RA map. Five of 138 developed to iAF by SVC firing, and SVC isolation based on the SSS-map was successfully achieved without SNI in the cases. Conclusion This study indicated iAF driven by SVC firing after PV isolation occurred in certain number of patients. The SSS-map before PV isolation was practical and showed the potential to be the mapping strategy avoid the SN injury in such cases.

Near-field detection and peak frequency metric for substrate and activation mapping of ventricular tachycardias in two- and three-dimensional circuits.

Successful ventricular arrhythmia (VA) ablation requires identification of functionally critical sites during contact mapping. Estimation of the peak frequency (PF) component of the electrogram (EGM) may improve correct near-field (NF) annotation to identify circuit segments on the mapped surface. In turn, assessment of NF and far-field (FF) EGMs may delineate the three-dimensional path of a ventricular tachycardia (VT) circuit. A proprietary NF detection algorithm was applied retrospectively to scar-related re-entry VT maps and compared with manually reviewed maps employing first deflection (FDcorr) for VT activation maps and last deflection (LD) for substrate maps. Ventricular tachycardia isthmus location and characteristics mapped with FDcorr vs. NF were compared. Omnipolar low-voltage areas, late activating areas, and deceleration zones (DZ) in LD vs. NF substrate maps were compared. On substrate maps, PF estimation was compared between isthmus and bystander sites. Activation mapping with entrainment and/or VT termination with radiofrequency (RF) ablation confirmed critical sites. Eighteen patients with high-density VT activation and substrate maps (55.6% ischaemic) were included. Near-field detection correctly located critical parts of the circuit in 77.7% of the cases compared with manually reviewed VT maps as reference. In substrate maps, NF detection identified deceleration zones in 88.8% of cases, which overlapped with FDcorr VT isthmus in 72.2% compared with 83.3% overlap of DZ assessed by LD. Applied to substrate maps, PF as a stand-alone feature did not differentiate VT isthmus sites from low-voltage bystander sites. Omnipolar voltage was significantly higher at isthmus sites with longer EGM durations compared with low-voltage bystander sites. The NF algorithm may enable rapid high-density activation mapping of VT circuits in the NF of the mapped surface. Integrated assessment and combined analysis of NF and FF EGM-components could support characterization of three-dimensional VT circuits with intramural segments. For scar-related substrate mapping, PF as a stand-alone EGM feature did not enable the differentiation of functionally critical sites of the dominant VT from low-voltage bystander sites in this cohort.

Single-beat mapping during programmed ventricular stimulation identifies infarct-related ventricular tachycardia isthmus sites

Abstract Introduction Complete characterization of reentrant ventricular tachycardia (VT) circuits using classical electrophysiological criteria and high-density mapping during VT is complex. Often, VT episodes cannot be fully characterized because of hemodynamic instability during the mapping procedure. This common limitation has motivated the implementation of mapping strategies during sinus rhythm or ventricular pacing aiming to identify scar regions associated with VT isthmuses or potential arrhythmogenicity. However, these strategies still require time-consuming catheter-based mapping. Purpose We aimed to develop and validate a single-beat mapping strategy during programmed ventricular stimulation (PVS) to identify scar regions associated with VT isthmus sites. We hypothesize that protected VT isthmuses within scar regions are characterized by larger activation time dispersion than surrounding scar areas not related to critical isthmus sites. Methods Experimental study including 16 pigs with established myocardial infarction (MI) in the anterior wall. Ten-to-twelve weeks after MI, pigs underwent left ventricular characterization using 3D late-gadolinium enhancement cardiac magnetic resonance imaging, and further invasive electroanatomical mapping to obtain high-density sequential activation maps during ventricular pacing and VT. High-density maps were compared with single-beat maps using a 64-pole basket catheter positioned in the left ventricle. After VT induction, high-density activation maps in well-tolerated VT episodes were used to identify VT isthmus sites. Simultaneous activation data from the 64-pole basket catheter were also obtained during PVS and VT. Off-line analysis was performed to: (i) validate single-beat activation maps during the baseline drive pacing cycle length (S1), and (ii) identify basket-catheter electrodes with the larger local activation time-dispersion score (LAT-DS) during PVS including up to 4 coupled extrastimuli (S2, S3, S4, S5) (Figure 1). LAT-DS was defined as the normalized product of the LAT of each electrode and the activation dispersion among its neighboring electrodes. Results Basket-catheter based single-beat activation maps during S1 pacing showed high correlation values with high-density sequential activation maps (N=16. R²=0.91). In 7 pigs, the VT isthmus site was fully characterized using high-density activation maps. During any of the coupled extrastimuli of the PVS protocol, basket catheter electrodes colocalizing with documented VT isthmus sites on high-density maps showed higher LAT-DS values compared to surrounding electrodes located on scar or healthy regions. Conversely, LAT values alone could not differentiate scar regions relevant for VT maintenance during PVS protocol (Figure 2). Conclusions Sixty-four pole single-beat activation maps during PVS identify left ventricular scar areas with higher than surrounding LAT-DS values that are associated with VT isthmus sites.Figure 1.Experimental modelFigure 2.A-Example. B-C-Full results

Identification of deceleration zones during sinus rhythm for locating critical isthmuses in left atrial macroreentrant tachycardias

Abstract Introduction Ablation of left atrial (LA) macroreentrant tachycardias (LAMT) poses considerable challenges, with issues such as tachycardia cycle length variations, multiple reentrant circuits, and tachycardia termination during entrainment maneuvers. Evaluating deceleration zones (DZ) through atrial pacing during sinus rhythm, and their correlation with potential critical conduction isthmuses (CI) in LAMT, remains unexplored. This approach may facilitate LAMT ablation. Objective To investigate the presence of DZ through atrial pacing during sinus rhythm and their association with LAMT critical conduction isthmuses (CI). Methods Patients who underwent LAMT high-density activation mapping with a 16-pole grid catheter were included. Conventional mapping (activation, voltage and entrainment mapping during tachycardia) was performed to localize the CI. Atrial pacing with three atrial extrastimuli (S2/S3/S4 with 500/500/300 ms coupling interval) was performed during sinus rhythm from the distal coronary sinus (CS). Isochronal late activation mapping (ILAM) of the S3 and S4 cycles was compared. Deceleration zones (DZ) were defined as an offset in the color scale of the activation map in an area with at least a radius of 10 mm. ILAMs were evaluated blindly, and DZs were compared with CIs defined by conventional mapping during tachycardia and validated by radiofrequency application termination. Results 18 p (60.50 ± 11.63 yo, 11 male) and 21 procedures were included. LAMT termination was successful in 18 out of 21 procedures (85.71%) and failed in 3 due to the epicardial component of the reentrant circuit. ILAM during CS pacing was achieved in 13 patients and was not possible in 5 p due to multiple LAMTs leading to empiric linear ablation in 1 and to recurrent induction of LAMT or AF during the pacing protocol. A DZ was identified in 13 out of 16 maps (81.25%) in the S3 map, which was more pronounced in the S4 map. In all these 13 maps, the final ablation site was within the DZ in the S4 map, terminating the tachycardia with focal RF applications in 11 and with extended in 2. Conclusions Deceleration zones identified through atrial pacing during sinus rhythm are prevalent in LAMT patients. These zones generally correspond to the critical conduction isthmus and offer a valuable method for mapping the reentrant circuit when mapping during stable LAMT is not feasible.

Anatomical and Electrophysiological Characteristics of Dual-Loop Re-Entry in Atypical Atrial Flutter: Implications for Mapping and Catheter Ablation.

Background: Atypical atrial flutter (AFL) can be challenging to ablate, especially when involving dual-loop re-entry. We sought to assess the electroanatomical characteristics of single- and dual-loop AFLs in patients undergoing catheter ablation. Methods: We analyzed 25 non-cavotricuspid isthmus-dependent macro-re-entrant AFL in 19 consecutive patients. Three-dimensional high-density activation mapping was performed, and active re-entry loops were confirmed by entrainment mapping. Results: Of 25 AFLs (24 left, 1 right atrial), 13 (52%) exhibited dual-loop re-entry. The most common circuits included, in 6/13 (46% of dual loops), a perimitral re-entry with a second loop around the right/left pulmonary veins (PV) and, in 6/13 (46%), involved a right PV ostium with a second loop around either a functional conduction block or another PV. Ablation at the common isthmus of dual-loop AFLs and at the critical isthmus of single-loop AFLs terminated the arrhythmia more frequently than ablation at a secondary isthmus of dual-loop AFLs (5/6 (83%) and 8/11 (73%) versus 1/8 (13%), respectively, p = 0.013). Conclusions: More than half of AFLs exhibited a dual-loop re-entrant mechanism. Most critical isthmuses were found at the mitral isthmus, the left atrial roof or right PV ostia. Ablation targeting the common isthmus resulted in a higher termination rate.

Electrophysiologic mechanism and ablation strategy for macroreentrant biatrial tachycardias after Cox-maze procedures

BackgroundDifferent types of recurrent atrial tachycardia (AT) after Cox-maze procedures have been reported, whereas biatrial tachycardia (BiAT) has not been systematically analyzed. ObjectiveIn this study, we retrospectively investigated the electrophysiologic characteristics of BiAT after Cox-maze procedures by use of an ultrahigh-density mapping system. MethodsOf a consecutive 76 patients who underwent catheter ablation of AT after Cox-maze procedures, 12 BiATs were identified. High-density activation mapping was performed in both the left atrium and right atrium in combination with entrainment pacing to confirm the circuit. ResultsWe classified these BiATs into 2 groups. In group 1 (7 patients), the bidirectional block of maze linear lesions to prevent the macroreentrant AT was achieved; the posterior interatrial connections were involved in the circuit. In group 2 (5 patients), the bidirectional block of maze linear lesions was not blocked, and the most common gap was located at the end of the linear lesion near the annulus. In group 1, all the ATs were terminated by targeting the corresponding left atrium end of the posterior interatrial connections. In group 2, the ATs were terminated by targeting the gap near the annulus. ConclusionThe optimal ablation strategy for BiATs after the maze procedure should be based on detailed demonstration of the circuit by high-density mapping.

Catheter ablation of left atrial tachyarrhythmia: predictors of recurrence after catheter ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Differently from catheter ablation (CA) of atrial fibrillation (AF), outcome data on CA of atrial re-entrant arrhythmias are scarce. Purpose We sought to evaluate predictors of recurrence at follow up in this setting. Methods We analysed consecutive patients undergoing mapping and CA left atrial tachyarrhythmia. Three-dimensional high-density activation and voltage maps were created for each investigated tachycardia by means of CARTO® system. Left atrial (LA) size was measured as the anteroposterior diameter on parasternal long axis view on transthoracic echocardiogram. Severe LA enlargement was defined for LA diameter >47 mm in women and >52 mm in men in accordance with guidelines. Results Eighty-eight patients were considered (67 ± 9 years old, 45% males) undergoing 94 CA procedures (1.1 ± 0.3 per patient). Most patient had past medical history of pulmonary vein isolation (57%). In the investigated population, 120 tachycardia morphologies were mapped and ablated. Acute procedural success was achieved in 97% of cases without any major complication. After a mean follow-up of 17 ± 11 months, the overall freedom from atrial arrhythmia was 58% and 65% after single and repeat procedures, respectively. Severe LA enlargement was the only variable associated with arrhythmia recurrence at follow-up and it was consistent after single and repeat procedures (Figure 1 A-B). Conclusion CA of complex left atrial tachyarrhythmia is safe and effective, and the mid- and long-term outcome is improved when LA is not severely enlarged. CA of should therefore be considered early in this patient population to achieve better clinical outcome.

PO-01-138 NON-INVASIVE 3-D MAPPING (ECGI) OF MACRO-REENTRANT ATRIAL ARRHYTHMIAS

Peri-valvular atrial arrhythmias are the most common macro-reentrant mechanism seen in both de-novo and repeat atrial fibrillation (AF) ablations. Standard 12-lead ECG’s poorly predict tachycardia mechanisms especially post AF ablation. Identifying the mechanism of tachycardia non-invasively could help in procedural planning, expedite the invasive procedure, and identify critical areas sustaining persistent AF in patients with concomitant AF. The objective was to determine if ECGi could identify the mechanism of atrial flutters in patients with or without prior AF ablations. 30 patients (11 de-novo, 19 prior ablation) underwent non-invasive propagation and phase mapping (CardioInsight, Medtronic, Inc) and intracardiac bi-atrial high-density activation mapping (HD Grid and Precision, Abbott Medical). An 8-segment model (RA lateral, RA anterior, CTI, Septum, LA anterior, LA lateral, CS, LA posterior) was used for directionality in the propagation maps, and a 9-segment model for phase map analysis was used for presence and localization of ‘rotational hinge points’ which can occur with wavefronts moving in different directions within close proximity. The precise tachycardia mechanism (counterclockwise (CCW) or clockwise (CW) and cavo-tricuspid isthmus (CTI) or mitral isthmus (MI) dependent) was determined by intracardiac activation maps, entrainment, and confirmed with termination by ablation. Directionality in a region was deemed concordant if non-invasive and intracardiac maps matched or was declared discordant/indeterminate. A total of 31 macro-reentrants maps were analyzed: 16 CCW-CTI; 7 CW-CTI; 4 CCW-MI; 4 CW-MI. Regional directional concordance percentages shown in theTable. A total of 30/31 phase maps identified at least one region as a 'rotational hinge point', with 26/31 maps showing paired 'hinge points'. Location of rotations are shown in the Figure. ECGi can be used in macro-reentant atrial arrhythmias to determine directionality of activation with best concordance on the lateral walls of both atria. In our study, 97% of peri-valvular atrial flutters had at least one 'rotational hinge point' with 84% showing them paired representing macro-reentant circuit. Posterior LA wall rotational area was present in all peri-mitral flutters. Additionally, paired 'hinge points' with lateral atrial wall directionality were the best determinants of the macro-reentant mechanism.Tabled 1Directional ConcordanceRA LatRA AntCTISeptumLA AntLA LatCSLA PostCCW-CTI88%69%88%44%44%--50%--CW-CTI71%43%71%43%43%--29%--CCW-MI100%50%--75%75%100%100%50%CW-MI100%60%--40%40%80%80%20% Open table in a new tab

Abstract 15782: A Rare Case of Septal Atrial Flutter

Background: Isthmus-dependent counterclockwise or clockwise flutter is well defined and responsive to radiofrequency ablation (RFA) of the cavotricuspidisthmus (CTI). However, inter-atrial septal (IAS) flutter is rare and occurs with IAS substrate abnormalities and prior cardiac surgery. Case: A 62-year-old female with paroxysmal AF on rivaroxaban, hypertension and diabetes mellitus presented with palpitations refractory to propafenone and metoprolol. She underwent successful isolation of all four pulmonary veins (PVs) and RFA of the CTI with demonstration of bidirectional block. A year later, she presented with atypical AFL (Fig 1A) failing cardioversion. During redo ablation, bipolar voltage map of the left atrium (LA) demonstrated durable isolation of all four PVs. Burst pacing (BP) from the coronary sinus (CS) up to 220ms did not induce AFL. The LA posterior box was isolated by creating a roof line and a line connecting the inferior veins (Fig 1B). No extra-PV triggers were noted on high dose isoproterenol. However, during the washout period, BP from the CS induced AFL with a tachycardia cycle length of 237ms, concentric CS activation and almost simultaneous activation along the crista in the right atrium (RA). High-density activation and coherent mapping of LA and RA suggested a micro-reentrant circuit over the posterior IAS with wavefront collision across the CTI (Fig 1C, D). Concealed entrainment was observed over the LA posterior septum near the transseptal puncture site. RFA successfully terminated the AFL. RFA was performed in a sequential unipolar fashion on both sides of the septum over areas of fractionation. No atrial arrhythmias were inducible with BP on or off isoproterenol. Patient remained in sinus rhythm at 9 month follow up. Conclusion: IAS flutter post AF ablation or cardiac surgery is rare, and management is challenging. While RFA has a 93% success rate, larger studies are required to further delineate this condition.

Macroreentrant scar-mediated atrial tachycardia terminated by a nonpropagated stimulus within a narrow diastolic isthmus: Electroanatomic correlation

A 76-year-old woman with coronary artery disease status post coronary artery bypass grafting and paroxysmal atrial fibrillation and flutter status post cavotricuspid isthmus ablation underwent radiofrequency (RF) ablation of recurrent, symptomatic atrial tachycardia (AT) (cycle length [CL] 378 ms). High-density activation mapping using a Biosense Webster (Diamond Bar, CA) PentaRay® catheter revealed a macroreentrant circuit rotating clockwise (right anterior oblique, caudal view) along the right atrial free wall and conducting slowly through a narrow isthmus (zigzag line) (Figure 1A).

Correlation between sinus rhythm deceleration zones and critical sites for localized reentrant atrial flutter: A retrospective multicenter analysis.

BackgroundAtypical left atrial flutter (AFL) may be macroreentrant or spatially localized. The relationship between the critical isthmus (CI) for localized reentry with sinus rhythm (SR) conduction slowing has not been systematically examined.ObjectiveTo examine the correlation between CI sites for localized AFL (L-AFL) and deceleration zones (DZ) identified by isochronal late activation mapping (ILAM) during baseline rhythm.MethodsPatients with localized AFL who underwent high-density activation mapping of both SR and AFL were retrospectively analyzed. L-AFL was defined as reentry restricted to 2 wall segments of the left atrium. CI was defined by activation mapping and sites of successful termination during ablation. DZ, defined as >3 isochrones within 1 cm radius during baseline rhythm, were correlated to the locations of the CI.ResultsThirty-one consecutive patients that underwent detailed sinus rhythm and AFL high-density activation maps were analyzed at 3 centers. A mean 4060 ± 3275 and 6209 ± 8656 points were collected in ILAM and AFL activation maps, respectively. At least 1 DZ (1.7 ± 0.77) was identified in all patients. ILAM showed 3.27 ± 0.52 isochrones per DZ (168 ± 32 ms), and co-localized to CI sites at a distance of 6.7 ± 3 mm. A total of 34% ± 14% of the AFL cycle length was contained within 0.5 cm of the DZ.ConclusionsIn patients with L-AFL, CI co-localized with DZ during baseline rhythm, suggesting that DZ mapping during SR may yield candidate targets for ablation as an adjunct to pulmonary vein isolation to prevent a subtype of AFL.

Evaluation of Directed Graph-Mapping in Complex Atrial Tachycardias.

Directed graph-mapping (DGM) is a novel operator-independent automatic tool that can be applied to the identification of the atrial tachycardia (AT) mechanism. In the present study, for the first time, DGM was applied in complex AT cases, and diagnostic accuracy was evaluated. Catheter ablation of ATs still represents a challenge, as the identification of the correct mechanism can be difficult. New algorithms for high-density activation mapping (HDAM) render an easier acquisition of more detailed maps; however, understanding of the mechanism and, thus, identification of the ablation targets, especially in complex cases, remains strongly operator-dependent. HDAMs acquired with the latest algorithm (COHERENT version 7, Biosense Webster, Irvine, California) were interpreted offline by 4 expert electrophysiologists, and the acquired electrode recordings with corresponding local activation times (LATs) were analyzed by DGM (also offline). Entrainment maneuvers (EM) were performed to understand the correct mechanism, which was then confirmed by successful ablation (13 cases were centrifugal, 10 cases were localized re-entry, 22 cases were macro-re-entry, and 6 were double-loops). In total, 51 ATs were retrospectively analyzed. We compared the diagnoses made by DGM were compared with those of the experts and with additional EM results. In total, 51 ATs were retrospectively analyzed. Experts diagnosed the correct AT mechanism and location in 33 cases versus DGM in 38 cases. Diagnostic accuracy varied according to different AT mechanisms. The 13 centrifugal activation patterns were always correctly identified by both methods; 2 of 10 localized reentries were identified by the experts, whereas DGM diagnosed 7 of 10. For the macro-re-entries, 12 of 22 were correctly identified using HDAM versus 13 of 22 for DGM. Finally, 6 of 6 double-loops were correctly identified by the experts, versus 5 of 6 for DGM. Even in complex cases, DGM provides an automatic, fast, and operator-independent tool to identify the AT mechanism and location and could be a valuable addition to current mapping technologies.

Use of high-density activation and voltage mapping in combination with entrainment to delineate gap-related atrial tachycardias post atrial fibrillation ablation.

An incomplete understanding of the mechanism of atrial tachycardia (AT) is a major determinant of ablation failure. We systematically evaluated the mechanisms of AT using ultra-high-resolution mapping in a large cohort of patients. We included 107 consecutive patients (mean age: 65.7 ± 9.2 years, males: 81 patients) with documented endocardial gap-related AT after left atrial ablation for persistent atrial fibrillation (AF). We analysed the mechanism of 134 AT (94 macro-re-entries and 40 localized re-entries) using high-resolution activation mapping in combination with high-density voltage and entrainment mapping. Voltage in the conducting channels may be extremely low, even <0.1 mV (0.14 ± 0.095 mV, 51 of 134 AT, 41%), and almost always <0.5 mV (0.03-0.5 mV, 133 of 134 AT, 99.3%). The use of multipolar Orion, HDGrid, and Pentaray catheters improved our accuracy in delineating ultra-low-voltage areas critical for maintenance of the circuit of endocardial gap-related AT. Conventional ablation catheters often do not detect any signal (noise level) even using adequate contact force, and only multipolar catheters of small electrodes and shorter interelectrode space can detect clear fractionated low-amplitude and high frequency signals, critical for re-entry maintenance. We performed a diagnosis in 112 out of 134 AT (83.6%) using only activation mapping and in 134 out of 134 AT (100%) using the combination of activation and entrainment mapping. High-resolution activation mapping in combination with high-density voltage and entrainment mapping is the ideal strategy to delineate the critical part of the circuit in endocardial gap-related re-entrant AT after AF ablation.

High-density mapping of de novo focal atrial tachycardias using a new software: Protected low-voltage areas by zones of conduction delay.

BackgroundThe pathophysiological mechanism of focal atrial tachycardias (AT) remains obscure.MethodsFifteen patients (6 males, age 45 ± 18) with focal AT underwent high‐density activation mapping using a new software called extended early‐meets‐late (EEML).ResultsIrrespective of the arrhythmia mechanism, low bipolar voltage fractionated signals (0.14 ± 0.10 mV) were seen at the earliest activation site. The mean low‐voltage area (LVA) at the earliest activation site was 3.2 ± 1.0 cm2. EEML mapping revealed zones of conduction delay at the borders of LVAs.ConclusionsLVAs protected by zones of slow conduction appears to play an important role in the initiation and maintenance of focal ATs.

1321From high-density mapping to low-density mapping: an approach to delineate the active circuit in complex atrial reentrant tachycardias

Abstract Funding Acknowledgements NA OnBehalf NA Background High-density activation maps during complex atrial reentrant tachycardias are challenging to interpret as they include the activation patterns of active and passive circuits. Entrainment mapping provides the identification of the active tachycardia circuit. However, current electroanatomic mapping systems are not capable to color-coded the information obtained from entrainment maneuvers. Objectives We sought to describe a mapping approach for ablation of complex atrial reentrant tachycardias in which high-density activation maps are transformed into low-density activation maps only displaying the active part of the tachycardia circuit. Methods We included consecutive patients with atypical atrial flutter. A high-density activation map was acquired during the index tachycardia. Subsequently, entrainment maneuvers were performed to generate a low-density activation map in which only the activation of the atria directly involved in the flutter circuit was displayed. Results Seventeen patients were included 82% male, mean age was 62 ± 7 years. Structural heart disease was present in 59% and 53% had a prior left atrial ablation procedure. Low-density activation maps were successfully generated from an average of 14 ± 3 entrainment points. Twenty circuits (95%) were identified in the left atrium and 1 (5%) in the right atrium. Ablation guided by low-density mapping successfully terminated all ARTs in 267 ± 353 seconds of radiofrequency application. Conclusion Low-density mapping based on entrainment maneuvers provides a precise delineation of the active circuit during complex ARTs and resulted in successful arrhythmia termination. This approach can be easily incorporated into clinical practice.

55Non-invasive ECG-imaging for identification of atrial arrhythmogenic low voltage substrate in patients with persistent atrial fibrillation

Abstract Background/Introduction Left atrial (LA) fibrosis is associated with increased arrhythmia recurrence rates after pulmonary vein isolation (PVI) and increased stroke risk in patients with atrial fibrillation (AF). So far, detection and quantification of LA fibrosis is only feasible by invasive electrophysiological mapping of low-voltage-substrate (LVS) or delayed enhancement areas in MRI. Purpose The aim of this study was to assess the distribution and extent of atrial fibrosis by non-invasive ECG-Imaging (ECGI) in patients with persistent AF prior to PVI. Methods Thirty-seven consecutive patients (66 ± 9 years, 84% male) presenting for their first PVI were included. Patients with AF were cardioverted into sinus rhythm (SR). One day prior to AF ablation procedure, patients underwent ECGI in SR using the 252-electrode-array (CardioInsight) and a low-X-ray-dose, non-injected cardiac CT-scan to assess the relationship between ECGI-electrodes and cardiac epicardial structures. Prior to PVI, high-density biatrial voltage and activation maps were acquired in SR (CARTO-3). Localization and extent of atrial LVS (relevant fibrosis: LA-LVS: ≥5cm2 at &amp;lt;0.5mV threshold) and biatrial activation times depicted by CARTO were compared with atrial activation/conduction times assessed by non-invasive ECGI. Presence of LA-LVS was classified according to its extent into 3 stages and compared to the inter- and intraatrial conduction delay in ECGI. Results Relevant atrial fibrosis was found in 17/37(46%) patients. Presence of biatrial LVS resulted in a linear increase of the biatrial activation time in CARTO-SR-maps (146 ± 18ms in patients without LVS vs 184 ± 27ms in patients with LVS, p &amp;lt; 0.001) and in non-invasive ECGI (133 ± 11ms vs 170 ± 20ms, p &amp;lt; 0.001). Both the extent of biatrial LVS and invasively measured total activation time correlated well with non-invasive total atrial conduction time (TACT) in ECGI (r = 0.91 and r = 0.82, respectively, figure). Moreover, the extent of LA-LVS showed an excellent correlation to TACT in ECGI (r = 0.89). A combination of inter-atrial (RA-LA) conduction delay and TACT in ECGI allowed to quantify the extent of LA-LVS and to distinguish between three stages of LA-LVS: Stage 1 (minimal LA-LVS: 1 ± 2cm2): ECGI revealed rapid RA&amp;LA activation with short TACT 132 ± 9ms; Stage 2 (moderate LA-LVS: 14 ± 8cm2 involving the anteroseptal LA) was associated with delayed LA activation and prolonged TACT measuring 161 ± 7ms; Stage 3 (extensive LA-LVS involving the anteroseptal and posterior LA: 26 ± 17cm2) was characterized by a significantly delayed LA activation with a TACT of 178 ± 24ms in ECGI. Conclusion Analysis of interatrial conduction delay and total atrial conduction time (TACT) in non-invasive ECGI allows accurate staging of patients with arrhythmogenic atrial LVS who present an increased risk for arrhythmia recurrences and stroke. Abstract Figure.

Automatic annotation of local activation time was improved in idiopathic right ventricular outflow tract ventricular arrhythmia by novel electrogram "Lumipoint" algorithm.

Precise automatic annotation of local activation time (LAT) is crucial for rapid high-density activation mapping in arrhythmia. However, it is still challenging in voltage-transitional areas where local low-amplitude near-field potentials are often obscured by large far-field potentials. The aim of this study was to explore the viability and validity of automatic identification of the earliest activation (EA) in idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT VAs) using a novel Lumipoint algorithm. Twenty-seven patients with RVOT VAs were mapped with Rhythmia mapping system. Lumipoint algorithms were applied to reannotate the initial activation regions retrospectively. The results showed that LATs were reannotated in 35.0 ± 11.4% points in the initial activation area from bipolar activation breakout time (BBO) to the its 40ms earlier timepoint. The automatically determined bipolar earliest activation time after Lumipoint reannotation (BEAT-lu: - 111.26 ± 12.13ms) was significantly earlier than that before (BEAT: - 108.67 ± 12.25ms, P = 0.000). Compared with manually corrected earliest activation time (EAT), the difference between EAT and BEAT-lu (DEAT-BEAT-lu: 6 (2-7) ms) was significantly smaller than that between EAT and BEAT (DEAT-BEAT/DEAT-UEA: 7 (4-11) ms, P = 0.000). The incidence of EAT and BEAT-lu being the same site was significantly higher than that between EAT and BEAT (48.15% vs 18.52%, P = 0.021). RVOT VAs often originate from voltage-transitional zone, and automatic annotation of LAT usually located at later high-amplitude far-field potential. Lumipoint algorithms could improve the accuracy of LAT automatic annotation, and it was plausible to ablate RVOT VAs just according to the automatically annotated BEAS-lu.

First experience and validation of the extended early meets late (EEML) tool as part of the novel CARTO software HD COLORING.

With CARTO HD COLORING, a new enhanced software-based map visualization is available to highlight among others potential areas of conduction block in complex arrhythmias (extended early meets late (EEML)). The ideal settings of thresholds are still unclear and are examined here by studying 12 left atrial arrhythmias. Ten patients with left atrial tachycardia underwent high-density activation mapping of the left atrium. Areas of local conduction block were visualized with different extended early meets late (EEML) thresholds (75/25%; 80/20%; 85/15%; 90/10%) and compared with ripple maps for verification. Settings of 80/20% or 85/15% were more accurate than the default settings of 75/25% in displaying the actual amount of conduction block as assessed by ripple maps. HD COLORING leads to further insights into complex tachycardias through a new Voxel Map Surface Concept and color-based visualization of local conduction block. It can be assumed that individual adaption of extended early meets late (EEML) thresholds should be applied for a more accurate visualization of local conduction block.

From High-Density Mapping to Low-Density Mapping: Outlining the Active Circuit in Complex Atrial Re-EntrantTachycardias.

The aim of this study was to describe a mapping approach for ablation of complex atrial re-entrant tachycardias (ARTs) in which high-density activation maps are transformed into low-density activation maps displaying only the active part of the tachycardia circuit. High-density activation maps during complex ARTs are challenging to interpret because they include the activation patterns of active and passive circuits. Entrainment mapping provides the identification of the active tachycardia circuit. However, current electroanatomic mapping systems are not capable of color-coding the information obtained from entrainment maneuvers. Seventeen consecutive patients with atypical atrial flutter were included. A high-density activation map was acquired during index tachycardia. Subsequently, entrainment maneuvers were performed to generate a low-density activation map in which only the activation of the atria directly involved in the flutter circuit was displayed. Of all patients included, 82% were men, and their mean age was 62 ± 7 years. Structural heart disease was present in 59%, and 53% had undergone prior left atrial ablation procedures. Low-density activation maps were successfully generated from an average of 14 ± 3 entrainment points. Twenty circuits (95%) were identified in the left atrium and 1 (5%) in the right atrium. Ablation guided by low-density mapping successfully terminated all ARTs in 267±353s of radiofrequency application. Low-density mapping based on entrainment maneuvers provides a precise delineation of the active circuit during complex ARTs and resulted in successful arrhythmia termination. This approach can be easily incorporated into clinical practice.