Individualized ablation strategy guided by live simultaneous global mapping to treat persistent atrial fibrillation

SuperMap algorithm: an efficient, safe and accurate modality for mapping and eliminating challenging cardiac arrhythmias

Even with the development of advanced catheter-based mapping systems, there remain several challenges in the electrophysiological evaluation and elimination of atrial arrhythmias. For instance, atrial tachycardias with irregular rates cannot be reliably mapped by systems that require stability in order to sequentially gather data points to be organized thereafter. Separately, these arrhythmias often arise following initial ablation for atrial fibrillation, posing logistic challenges. Here, we present the available literature summarizing the use of a non-contact mapping catheter, the AcQMap catheter, in conjunction with SuperMap, an algorithm that compiles a large number of non-contact data points from multiple catheter positions within the atria. These studies demonstrate the efficiency, safety and accuracy of this technology.

Impact of Adenosine on Wavefront Propagation in Persistent Atrial Fibrillation: Insights From Global Noncontact Charge Density Mapping of the Left Atrium

Background

Adenosine shortens action potential duration and refractoriness and provokes atrial fibrillation. This study aimed to evaluate the effect of adenosine on mechanisms of wavefront propagation during atrial fibrillation.

Methods and Results

The study included 22 patients undergoing catheter ablation for persistent atrial fibrillation. Left atrial mapping was performed using the AcQMap charge density system before and after administration of intravenous adenosine at 1 or more of 3 time points during the procedure (before pulmonary vein isolation, after pulmonary vein isolation, and after nonpulmonary vein isolation ablation). Wave‐front propagation patterns were evaluated allowing identification and quantification of localized rotational activation (LRA), localized irregular activation, and focal firing. Additional signal processing was performed to identify phase singularities and calculate global atrial fibrillation cycle length and dominant frequency. A total of 35 paired maps were analyzed. Adenosine shortened mean atrial fibrillation cycle length from 181.7±14.3 to 165.1±16.3, (mean difference 16.6 ms; 95% CI, 11.3–21.9, P<0.0005) and increased dominant frequency from 6.0±0.7 Hz to 6.6±0.8 Hz (95% CI, 0.4–0.9, P<0.0005). This was associated with a 50% increase in the number of LRA occurrences (16.1±7.6–24.2±8.1; mean difference 8.1, 95% CI, 4.1–12, P<0.0005) as well as a 20% increase in the number of phase singularities detected (30.1±7.8–36.6±9.3; mean difference 6.5; 95% CI, 2.6–10.0, P=0.002). The percentage of left atrial surface area with LRA increased with adenosine and 42 of 70 zones (60%) with highest density of LRA coincided with high density LRA zones at baseline with only 28% stable across multiple maps.

Conclusions

Adenosine accelerates atrial fibrillation and promotes rotational activation patterns with no impact on focal activation. There is little evidence that rotational activation seen with adenosine represents promising targets for ablation aimed at sites of stable arrhythmogenic sources in the left atrium.

Atrial Fibrillation Mechanisms Before and After Pulmonary Vein Isolation Characterized by Non-Contact Charge Density Mapping

BACKGROUND

The interaction of pulmonary vein and putative non-pulmonary triggers of atrial fibrillation (AF) remains unclear, and has yet to translate into patient tailored ablation strategies.

OBJECTIVE

To use non-contact mapping to detail the global conduction patterns in paroxysmal and persistent AF and how they are modified during pulmonary vein ablation.

METHODS

40 patients at atrial fibrillation ablation underwent mapping using a non-contact catheter (AcQMap, Acutus Medical Inc) before and after pulmonary vein isolation (PVI). Propagation history maps were analysed post-procedure for each patient to categorise conduction patterns into Focal, Organised reentrant and Disorganized patterns.

RESULTS

Activation patterns identified by using a non-contact mapping system can be sub-classified from three main patterns into subtypes (MacroReentrant and LocalisedReentrant subtypes, Disorganized 1 and Disorganized 2 subtypes). Persistent AF demonstrated more D-Patterns, and less O-Patterns and F-Patterns than paroxysmal AF. In addition, PAF patients inducible after PVI demonstrated a greater number and higher prevalence of MR subtypes than those non-inducible. PVs remained the critical region and included almost one third of all patterns across any AF-types. PVI was effective to eliminate PV-related functional phenotypes, and impacted on recurrence with other patterns.

CONCLUSION

Activation patterns identified using AcQMap can be classified into three main patterns (F-Patterns, O-Patterns and D-Patterns) as well as subtypes (MR and LR subtype, D1 and D2 subtype). PerAF was different from PAF in demonstrating a greater region number and prevalence of D-Patterns, but lower region number and prevalence of O-Patterns and F-Patterns.

Global Substrate Mapping and Targeted Ablation with Novel Gold-tip Catheter in De Novo Persistent AF

Results from catheter ablation for persistent AF are suboptimal, with no strategy other than pulmonary vein isolation showing clear benefit. Recently employed empirical strategies beyond pulmonary vein isolation involve widespread atrial ablation in all patients and do not take into account patient-specific differences in AF mechanisms or phenotype. Charge density mapping using the non-contact AcQMap system (Acutus Medical) allows visualisation of whole-chamber activation during AF and reveals localised patterns of complex activation thought to represent important mechanisms for AF maintenance that can be targeted with focal ablation. In this review, the authors outline the fundamentals of this technology, the initial data exploring the mechanistic role of activation patterns seen and the application to ablation of persistent AF.

Non-contact whole-chamber charge density mapping of the left ventricle: preclinical evaluation in a sheep model

BACKGROUND

Conventional contact-based electroanatomic mapping is poorly suited for rapid or dynamic ventricular arrhythmias. Whole-chamber charge density (CD) mapping could efficiently characterize complex ventricular tachyarrhythmias and yield insights into their underlying mechanisms.

OBJECTIVE

This study sought to evaluate the feasibility and accuracy of non-contact whole-chamber left ventricular (LV) CD mapping, and to characterize CD activation patterns during sinus rhythm, ventricular pacing, and ventricular fibrillation (VF).

METHODS

Ischemic scar as defined by CD amplitude thresholds was compared to late gadolinium enhancement criteria on magnetic resonance imaging using an iterative closest point algorithm. Electrograms recorded at sites of tissue contact were compared to the nearest non-contact CD-derived electrograms to calculate signal morphology cross-correlations and time differences. Regions of consistently slow conduction were examined relative to areas of scar and to localized irregular activation (LIA) during VF.

RESULTS

Areas under receiver operating characteristic curves (AUCs) of CD-defined dense and total LV scar were 0.92 ± 0.03 and 0.87 ± 0.06, with accuracies of 0.86±0.03 and 0.80±0.05, respectively. Morphology cross-correlation between 8,677 contact and corresponding non-contact electrograms was 0.93±0.10, with a mean time difference of 2.5±5.6 msec. Areas of consistently slow conduction tended to occur at scar borders and exhibited spatial agreement with LIA during VF (AUC 0.90±0.02).

CONCLUSION

Non-contact LV CD mapping can accurately delineate ischemic scar. CD-derived ventricular electrograms correlate strongly with conventional contact-based electrograms. Regions with consistently slow conduction are often at scar borders and tend to harbor LIA during VF.

Localization of Right Ventricular Outflow Tract Premature Ventricular Complexes Using a Novel Mapping System

Premature ventricular complexes (PVCs) are common in the general population, usuallyasymptomatic, and deemed to be benign in structurally normal hearts. The spectrum of "benign" outflow tract PVCs ranges from single PVCs to recurrent non-sustained ventricular tachycardia (NSVT). Short-coupled right ventricular outflow tract (RVOT) PVCs may trigger polymorphic ventricular tachycardia (VT) in some patients and can be high risk. In many patients, PVCs can be morefrequent and cause symptoms ofpalpitations, shortness of breath, dizziness, and heart failure.In the presence of underlying heart disease, they may indicate an increasedrisk of adverse cardiovascular outcomes. A high PVC burdenmay lead to ventricular dysfunction and worsen underlying cardiomyopathy.PVCs may also be a marker of underlying pathophysiologic processes such as myocarditisand other acquired and inherited infiltrative cardiomyopathies. In this unique case report, we describe the use of a novel non-contact mapping array for mapping RVOT PVCs.

Treatment of brief episodes of highly symptomatic supraventricular and ventricular arrhythmias: a methodological review

INTRODUCTION

Patients with brief arrhythmias are a challenging group to treat effectively with catheter ablation. Current standard approaches for the localization and treatment of brief arrhythmias suffer from several limitations, including the lack of spatiotemporal stability and adequate resolution. Recently, novel methods became available that open new perspectives and can be implemented both on the atrial and ventricular level to approach the diagnosis and treatment of these arrhythmias.

AREAS COVERED

In this paper, we demonstrate in each section a novel mapping modality that has a potential to approach arrhythmias considered unmappable in the past. After describing the method, we focused on the most important features of each system that makes mapping of short arrhythmias feasible. At the end of each section, we gave a short overview about necessary developments to improve the utility of these systems in the near future.

EXPERT OPINION

Treating brief episodes of tachycardias remains a challenge and can cause significant frustration for electrophysiologists. Although the broadening of the indication is clearly visible, currently available sequential mapping techniques often fail to map short-lived arrhythmias. New beneficial technological features permit the mapping of these previously considered unmappable arrhythmias, and offer a new perspective in their management.

Clinical utility of non-contact charge density 'SuperMap' algorithm for the mapping and ablation of organized atrial arrhythmias

AIMS

SuperMap is a novel non-contact algorithm for the mapping of organized atrial arrhythmias. We prospectively evaluated SuperMap during mapping and ablation of atrial tachycardias (ATs) and paced rhythms and compared to conventional high-density contact mapping.

METHODS AND RESULTS

Consecutive patients undergoing SuperMap guided ablation of pre-existing ATs or AT developed during atrial fibrillation ablation procedures were included together with maps obtained during pacing to assess block in linear lesions. The time taken to obtain diagnostic maps was measured together with the number of electrogram (EGM) points and accuracy compared to the arrhythmia diagnosis confirmed using a combination of map findings, entrainment, and response to ablation. In a subgroup of patients, concurrent contact mapping was performed with contact and SuperMap analysed by separate operators blinded to the other technique. The time taken to generate a diagnostic map, EGM number, and map accuracy was compared. Thirty-one patients (62 maps) were included with contact mapping performed in 19 [39 maps (33 for AT)]. SuperMap acquisition time was 314 s [interquartile range (IQR) 239-436]. The median number of EGM points used per map was 5399 (IQR 3279-8677). SuperMap was faster than contact mapping [394 ± 219 s vs. 611 ± 331 s; difference 217 s, 95% confidence interval (CI) 116-318, P < 0.0005]. The number of EGM points used per map was higher for SuperMap (7351 ± 5054 vs. 3620 ± 3211; difference 3731, 95% CI 2073-5388, P < 0.0005). SuperMap and contact mapping were accurate in 92% and 85% of maps, respectively, P = 0.4805.

CONCLUSION

SuperMap non-contact charge density mapping is a rapid and reliable approach to guide the ablation of complex atrial arrhythmias.

Initial experience with AcQMap catheter for treatment of persistent atrial fibrillation and atypical atrial flutter

Introduction

The AcQMap High Resolution Imaging and Mapping System was recently introduced. This system provides 3D maps of electrical activation across an ultrasound-acquired atrial surface.

Methods

We evaluated the feasibility and the acute and short-term efficacy and safety of this novel system for ablation of persistent atrial fibrillation (AF) and atypical atrial flutter.

Results

A total of 21 consecutive patients (age (mean ± standard deviation) 62 ± 8 years, 23% female) underwent catheter ablation with the use of the AcQMap System. Fourteen patients (67%) were treated for persistent AF and 7 patients (33%) for atypical atrial flutter. Eighteen patients (86%) had undergone at least one prior ablation procedure. Acute success, defined as sinus rhythm without the ability to provoke the clinical arrhythmia, was achieved in 17 patients (81%). At 12 months, 4 patients treated for persistent AF (29%) and 4 patients treated for atypical flutter (57%) remained in sinus rhythm. Complications included hemiparesis, for which intra-arterial thrombolysis was given with subsequent good clinical outcome (n = 1), and complete atrioventricular block, for which a permanent pacemaker was implanted (n = 2). No major complications attributable to the mapping system occurred.

Conclusion

The AcQMap System is able to provide fast, high-resolution activation maps of persistent AF and atypical atrial flutter. Despite a high acute success rate, the recurrence rate of persistent AF was relatively high. This may be due to the selection of the patients with therapy-resistant arrhythmias and limited experience in the optimal use of this mapping system that is still under development.

Supplementary Information

The online version of this article (10.1007/s12471-021-01636-w) contains supplementary material, which is available to authorized users.

Novel aggregated multiposition noncontact mapping of atrial tachycardia in humans: From computational modeling to clinical validation

BACKGROUND

A novel aggregated multiposition noncontact mapping (AMP-NCM) algorithm is proposed to diagnose cardiac arrhythmias.

OBJECTIVE

The purpose of this study was to computationally determine an accuracy threshold and to compare the accuracy and clinical utility of AMP-NCM to gold standard contact mapping.

METHODS

In a cellular automata model, the number of catheter positions and chamber coverage were varied to establish accuracy requirements for clinically relevant AMP-NCM. This guided the clinical study protocol. In a prospective cohort of patients with atrial tachycardia (AT), noncontact mapping (NCM) recordings from a single position (SP) and multiple positions were compared to contact mapping with a high-density multipolar catheter using morphology and timing differences of reconstructed signals. Identification of AT mechanisms and ablation targets using both AMP-NCM and contact mapping were randomly evaluated by 5 blinded reviewers.

RESULTS

AMP-NCM accuracy was asymptotic at 60 catheter positions in computational modeling. Twenty patients (age 65 ± 12 years; 19 male) with 26 ATs (5 focal, 21 reentrant) were studied. Morphologic correlation of signals derived from AMP-NCM was significantly better than those from SP-NCM compared to contact signals (median 0.93 vs 0.76; P <.001). AMP-NCM generated maps more rapidly than contact mapping (3 ± 1 minutes vs 13 ± 6 minutes; P <.001) and correctly diagnosed AT mechanisms in 25 of 26 maps (96%). Overall, 80% of arrhythmia mechanisms were correctly identified using AMP-NCM by blinded reviewers.

CONCLUSION

Once 60 catheter positions were achieved, AMP-NCM successfully diagnosed mechanisms of AT and identified treatment sites equal to gold standard contact mapping in 3 minutes of procedural time.

Spatial and temporal variability of rotational, focal, and irregular activity: Practical implications for mapping of atrial fibrillation

BACKGROUND

Charge density mapping of atrial fibrillation (AF) reveals dynamic localized rotational activation (LRA), irregular activation (LIA) and focal firing (FF). Their spatial stability, conduction characteristics and the optimal duration of mapping required to reveal these phenomena and has not been explored.

METHODS

Bi-atrial mapping of AF propagation was undertaken using AcQMap (Acutus Medical) and variability of activation patterns quantified up to a duration of 30 s. The frequency of each pattern was quantified at each unique point of the chamber over two separate 30-s recordings before ablation and R² calculated to quantify spatial stability. Regions with the highest frequency were identified at increasing time durations and compared to the result over 30 s using Cohen's kappa. Properties of regions with the most stable patterns were assessed during sinus rhythm and extrastimulus pacing.

RESULTS

In 21 patients, 62 paired LA and RA maps were obtained. LIA was highly spatially stable with R² between maps of 0.83 (0.71-0.88) compared to 0.39 (0.24-0.57), and 0.64 (0.54-0.73) for LRA and FF, respectively. LIA was most temporally stable with a kappa of >0.8 reached by 12 s. LRA showed greatest variability with kappa >0.8 only after 22 s. Regions of LIA were of normal voltage amplitude (1.09 mv) but showed increased conduction heterogeneity during extrastimulus pacing (p = .0480).

CONCLUSION

Irregular activation patterns characterized by changing wavefront direction are temporally and spatially stable in contrast with LRA that is transient with least spatial stability. Focal activation appears of intermediate stability. Regions of LIA show increased heterogeneity following extrastimulus pacing and may represent fixed anatomical substrate.

The Electrophysiology of Atrial Fibrillation: From Basic Mechanisms to Catheter Ablation

The electrophysiology of atrial fibrillation (AF) has always been a deep mystery in understanding this complex arrhythmia. The pathophysiological mechanisms of AF are complex and often remain unclear despite extensive research. Therefore, the implementation of basic science knowledge to clinical practice is challenging. After more than 20 years, pulmonary vein isolation (PVI) remains the cornerstone ablation strategy for maintaining the sinus rhythm (SR). However, there is no doubt that, in many cases, especially in persistent and long-standing persistent AF, PVI is not enough, and eventually, the restoration of SR occurs after additional intervention in the rest of the atrial myocardium. Substrate mapping is a modern challenge as it can reveal focal sources or rotational activities that may be responsible for maintaining AF. Whether these areas are actually the cause of the AF maintenance is unknown. If this really happens, then the targeted ablation may be the solution; otherwise, more rough techniques such as atrial compartmentalization may prove to be more effective. In this article, we attempt a broad review of the known pathophysiological mechanisms of AF, and we present the recent efforts of advanced technology initially to reveal the electrical impulse during AF and then to intervene effectively with ablation.

Novel noncontact charge density map in the setting of post-atrial fibrillation atrial tachycardias: first experience with the Acutus SuperMap Algorithm

PURPOSE

The purpose of this study was to evaluate the safety and feasibility of the new high-resolution mapping algorithm SuperMap (Acutus Medical, CA, USA) in identifying and guiding ablation in the setting of regular atrial tachycardias following index atrial fibrillation (AF) ablation.

METHODS

Seven consecutive patients who underwent a radiofrequency catheter ablation guided by the novel noncontact charge density (CD) SuperMap for atrial tachycardia were prospectively enrolled in our study.

RESULTS

Arrhythmogenic substrate was identified in all seven patients. Mean number of EGM per map was 5859.7 ± 4348.5 points. Three patients (43%) exhibited focal tachycardia mechanisms in the left atrium, alternating from anteroseptal right superior pulmonary vein (RSPV), posterior in proximity of left inferior pulmonary vein (LIPV), and interarial septum in proximity of fossa ovalis, respectively. Four patients exhibited macroreentrant mechanism. In 3 of these patients, SuperMap detected mitral isthmus-dependent flutters with tachycardia cycle lengths of 240, 270 and 420 ms, respectively. In one patient, the mechanism was a macroreentrant tachycardia with the critical isthmus located between the crista terminalis and atriotomy. The mean ablation time (min) was 18.2 ± 12.5 and the mean procedural duration time was 56.4 ± 12.1 min. No minor or major complications occurred.

CONCLUSION

The novel high-resolution mapping algorithm SuperMap proved to be safe, fast, and feasible in identifying and guiding ablation in the setting of regular atrial tachycardias following index AF ablation.

Individualized ablation strategy to treat persistent atrial fibrillation: Core-to-boundary approach guided by charge-density mapping

BACKGROUND

Noncontact charge-density mapping allows rapid real-time global mapping of atrial fibrillation (AF), offering the opportunity for a personalized ablation strategy.

OBJECTIVE

The purpose of this study was to compare the 2-year outcome of an individualized strategy consisting of pulmonary vein isolation (PVI) plus core-to-boundary ablation (targeting the conduction pattern core with an extension to the nearest nonconducting boundary) guided by charge-density mapping, with an empirical PVI plus posterior wall electrical isolation (PWI) strategy.

METHODS

Forty patients (age 62 ± 12 years; 29 male) with persistent AF (10 ± 5 months) prospectively underwent charge-density mapping-guided PVI, followed by core-to-boundary stepwise ablation until termination of AF or depletion of identified cores. Freedom from AF/atrial tachycardia (AT) at 24 months was compared with a propensity score-matched control group of 80 patients with empirical PVI + PWI guided by conventional contact mapping.

RESULTS

Acute AF termination occurred in 8 of 40 patients after charge-density mapping-guided PVI alone and in 21 of the remaining 32 patients after core-to-boundary ablation in the study cohort, compared with 8 of 80 (10%) in the control cohort (P <.001). On average, 2.2 ± 0.6 cores were ablated post-PVI before acute AF termination. At 24 months, freedom from AF/AT after a single procedure was 68% in the study group vs 46% in the control group (P = .043).

CONCLUSION

An individualized ablation strategy consisting of PVI plus core-to-boundary ablation guided by noncontact charge-density mapping is a feasible and effective strategy for treating persistent AF, with a favorable 24-month outcome.

Spectral characterization and impact of stepwise ablation protocol including LAA electrical isolation on persistent AF

OBJECTIVES

To study how left atrial appendage electrical isolation (LAAEI) impacts atrial dominant frequency (DF) in patients with long-standing persistent atrial fibrillation (LSPAF).

BACKGROUND

LAAEI is associated with a high probability of freedom from atrial fibrillation (AF) and spectral analysis may identify high-frequency sources. How LAAEI impacts the AF dynamics and the subgroup of LSPAF patients in whom LAAEI would be most beneficial, is unclear.

METHODS

Twenty patients with LSPAF were included in the study. Fast Fourier transforms (FFT) were performed on atrial electrograms recorded from 13 sites in the LA and RA. The highest peak frequency was defined as DF.

RESULTS

There was no significant difference in DF between atrial sites except for at the superior vena cava which had the lowest DF at baseline. Stepwise ablation consisting of circumferential pulmonary vein isolation and a linear ablation set of mitral isthmus and roof significantly reduced the DF within the coronary sinus (CS) (5.93 ± 0.98 Hz vs. 5.09 ± 0.72 Hz, p < .05) and the LA posterior wall (LApos) (6.26 ± 0.92 Hz vs. 5.43 ± 0.98 Hz, p < .01). LAAEI preferentially further decreased the DF at the LApos (p < .01), but not at the CS. In cases where there was < 13.6% reduction in the DF of the LApos following the stepwise ablation, the addition of LAAEI was associated with an increased restoration of sinus rhythm (55%, p < .05).

CONCLUSION

LAAEI in addition to stepwise ablation results in further reduction of the DF in the LApos, which is associated with acute termination of AF and favorable ablation outcome.

Diverse activation patterns during persistent atrial fibrillation by noncontact charge-density mapping of human atrium

BACKGROUND

Global simultaneous recording of atrial activation during atrial fibrillation (AF) can elucidate underlying mechanisms contributing to AF maintenance. A better understanding of these mechanisms may allow for an individualized ablation strategy to treat persistent AF. The study aims to characterize left atrial endocardial activation patterns during AF using noncontact charge-density mapping.

METHODS

Twenty-five patients with persistent AF were studied. Activation patterns were characterized into three subtypes: (i) focal with centrifugal activation (FCA); (ii) localized rotational activation (LRA); and (iii) localized irregular activation (LIA). Continuous activation patterns were analyzed and distributed in 18 defined regions in the left atrium.

RESULTS

A total of 144 AF segments with 1068 activation patterns were analyzed. The most common pattern during AF was LIA (63%) which consists of four disparate features of activation: slow conduction (45%), pivoting (30%), collision (16%), and acceleration (7%). LRA was the second-most common pattern (20%). FCA accounted for 17% of all activations, arising frequently from the pulmonary veins (PVs)/ostia. A majority of patients (24/25; 96%) showed continuous and highly dynamic patterns of activation comprising multiple combinations of FCA, LRA, and LIA, transitioning from one to the other without a discernible order. Preferential conduction areas were typically seen in the mid-anterior (48%) and lower-posterior (40%) walls.

CONCLUSION

Atrial fibrillation is characterized by heterogeneous activation patterns identified in PV-ostia and non-PV regions throughout the LA at varying locations between individuals. Clinical implications of individualized ablation strategies guided by charge-density mapping need to be determined.

Validation of Dipole Density Mapping During Atrial Fibrillation and Sinus Rhythm in Human Left Atrium

OBJECTIVES

This study sought to validate the accuracy of noncontact electrograms against contact electrograms in the left atrium during sinus rhythm (SR) and atrial fibrillation (AF).

BACKGROUND

Noncontact mapping offers the opportunity to assess global cardiac activation in the chamber of interest. A novel noncontact mapping system, which records intracardiac voltage to derive cellular charge sources (dipole density), allows real-time mapping of AF to guide ablation.

METHODS

Noncontact and contact unipolar electrogram pairs were recorded simultaneously from multiple locations. Morphology correlation and timing difference of reconstructed electrograms obtained from a noncontact catheter were compared with those from contact electrograms obtained from a contact catheter at the same endocardial locations.

RESULTS

A total of 796 electrogram pairs in SR and 969 electrogram pairs in AF were compared from 20 patients with persistent AF. The median morphology correlation and timing difference (ms) in SR was 0.85 (interquartile range [IQR]: 0.71 to 0.94) and 6.4 ms (IQR: 2.6 to 17.1 ms); in AF was 0.79 (IQR: 0.69 to 0.88) and 14.4 ms (IQR: 6.7 to 26.2 ms), respectively. The correlation was stronger and the timing difference was less when the radial distance (r) from the noncontact catheter center to the endocardium was ≤ 40 versus > 40 mm; 0.87 (IQR: 0.72 to 0.94) versus 0.73 (IQR: 0.56 to 0.88) and 5.7 ms (IQR: 2.6 to 15.4 ms) versus 15.1 ms (IQR: 4.1 to 27.7 ms); p < 0.01 when in SR; 0.81 (IQR: 0.69 to 0.89) versus 0.67 (IQR: 0.45 to 0.82) and 12.3 ms (IQR: 5.9 to 21.8 ms) versus 28.3 ms (IQR: 16.2 to 36.0 ms); p < 0.01 when in AF.

CONCLUSIONS

This novel noncontact dipole density mapping system provides comparable reconstructed atrial electrogram measurements in SR or AF in human left atrium when the anatomical site of interest is ≤40 mm from the mapping catheter.