Identification of critical isthmus using coherent mapping in patients with scar-related atrial tachycardia

Atypical Atrial Flutter: Electrophysiological Characterization and Effective Catheter Ablation

Atrial flutter (AFL), defined as macro-re-entrant atrial tachycardia, is associated with debilitating symptoms, stroke, heart failure, and increased mortality. AFL is classified into typical, or cavotricuspid isthmus (CTI)-dependent, and atypical, or non-CTI-dependent. Atypical AFL is a heterogenous group of re-entrant atrial tachycardias that most commonly occur in patients with prior heart surgery or catheter ablation. The ECG pattern is poorly predictive of circuit anatomy but may still provide mechanistic insight. AFL is difficult to manage medically and catheter ablation is the preferred treatment for most patients. Recent progress in technology and clinical electrophysiology has led to detailed characterization of re-entry circuits and effective ablation strategies. Combined activation and entrainment mapping are key to identifying the re-entry circuit. The presence of a slow-conducting isthmus, localized re-entry, dual-loop re-entry or bystander loops may lead to misleading activation maps but can be identified by electrogram examination and entrainment mapping. In the occasional patient without inducible AFL, substrate mapping in sinus rhythm may be a viable strategy. Long-term ablation success requires the creation of a transmural continuous lesion across a critical component of the re-entry circuit. Procedural endpoints include bidirectional conduction block across linear lesions and non-inducibility of atrial tachycardia. The present review discusses the epidemiology, mechanisms, ECG characteristics, electrophysiological characterization, and catheter ablation of atypical AFL.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

Catheter ablation for atrial tachycardia in pediatric patients: a single-center experience

Purpose

Atrial tachycardia is an uncommon supraventricular tachycardia in children. It is often drug-resistant and likely to occur concomitantly with tachycardia-induced cardiomyopathy, making radiofrequency catheter ablation the preferred treatment. The aim of this study was to assess the feasibility, safety, and effectiveness of radiofrequency catheter ablation for the treatment of different types of atrial tachycardia in children, particularly in those with drug-resistant and tachycardia-induced cardiomyopathy.

Methods

A total of 28 children with atrial tachycardia (including focal atrial tachycardia and atrial flutter) who underwent atrial radiofrequency ablation at the Children's Hospital Affiliated to Chongqing Medical University from May 2018 to December 2023 were included. The baseline characteristics, preoperative medication, surgical information, and postoperative follow-up data of these children were analyzed statistically.

Results

The mean age patients at ablation was 10.24 ± 3.40 years. A total of 78.6% of the patients (22/28) who received preoperative pharmacological treatment had intermittent or persistent atrial tachycardia. Of the 28 children who underwent radiofrequency ablation, 24 (85.7%) were diagnosed with focal atrial tachycardia, three (10.7%) with atrial flutter, and one (3.6%) with both. No postoperative complications occurred in any patient. The immediate ablation success rate in the 25 patients with focal atrial tachycardia was 96.0% (24/25). After 26.89 ± 18.17 months of follow-up, only three patients had recurrence. The ablation difficulty of focal atrial tachycardia originating in the appendage was higher than that originating in the non-atrial appendage (44.4% vs. 6.3%, p = 0.01). The success rate of ablation for atrial flutter was 100%, except in one child with underlying cardiomyopathy who experienced recurrence. Final success was achieved in 25 of the 28 patients (89.2%) at the end of the follow-up period. In addition, eight children (28.6%) in this study were diagnosed with tachycardia-induced cardiomyopathy, with significantly increased ejection fraction and shortening rate after radiofrequency ablation (p < 0.01), whereas the left ventricular end-systolic diameter were not significantly reduced during the follow-up period (p > 0.05).

Conclusion

Radiofrequency catheter ablation is safe and effective for the treatment of atrial tachycardia in children in the short- and long-term.It can be used as the first treatment option for children with medically refractory atrial tachycardia and tachycardia-induced cardiomyopathy.

Pacing cycle length-dependent electrophysiologic changes in left atrium: Poor validity of using low-voltage area and slow conduction area under specific pacing cycle length as absolute substrates of atrial fibrillation

BACKGROUND

Pacing cycle length (PCL)-dependent changes in left atrial (LA) electrophysiologic properties have not been fully elucidated.

OBJECTIVE

We aimed to elucidate these changes using a high-resolution mapping system.

METHODS

Forty-eight patients underwent atrial fibrillation ablation with RHYTHMIA HDx. Paired LA maps under a baseline PCL (600 ms) and rapid PCL (300 ms) were acquired after pulmonary vein isolation under right atrial appendage pacing. The PCL-dependent change in the low-voltage area (LVA; area with <0.5 mV bipolar voltage), LA activation time (interval from first LA activation to wavefront collision at lateral wall), regional mean voltage, regional mean wave propagation velocity, and slow conduction area (area with <0.3 m/s wave propagation velocity) were quantitatively analyzed.

RESULTS

Under the rapid PCL, the total LVA was significantly increased (7.6 ± 9.5 cm2 vs 6.7 ± 7.6 cm2; P = .031), especially in patients with a 10 cm2 LVA on the baseline PCL map (21.5 ± 9.1 cm2 vs 18.1 ± 6.5 cm2; P = .013). The LA activation time was also prolonged (87.9 ± 16.2 ms vs 84.0 ± 14.0 ms; P < .0001). Although the rapid PCL did not decrease the regional mean voltage, it significantly decreased the regional mean wave propagation velocity and increased the slow conduction area in all measured regions.

CONCLUSION

LVA and slow conduction area can be emphasized by rapid PCL LA mapping. There may be poor validity in using these areas as absolute atrial fibrillation substrates without considering the PCL-dependent changes.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

Automated prediction of isthmus areas in scar-related atrial tachycardias using artificial intelligence

INTRODUCTION

Ablation of scar-related reentrant atrial tachycardia (SRRAT) involves identification and ablation of a critical isthmus. A graph convolutional network (GCN) is a machine learning structure that is well-suited to analyze the irregularly-structured data obtained in mapping procedures and may be used to identify potential isthmuses.

METHODS

Electroanatomic maps from 29 SRRATs were collected, and custom electrogram features assessing key tissue and wavefront properties were calculated for each point. Isthmuses were labeled off-line. Training data was used to determine the optimal GCN parameters and train the final model. Putative isthmus points were predicted in the training and test populations and grouped into proposed isthmus areas based on density and distance thresholds. The primary outcome was the distance between the centroids of the true and closest proposed isthmus areas.

RESULTS

A total of 193 821 points were collected. Thirty isthmuses were detected in 29 tachycardias among 25 patients (median age 65.0, 5 women). The median (IQR) distance between true and the closest proposed isthmus area centroids was 8.2 (3.5, 14.4) mm in the training and 7.3 (2.8, 16.1) mm in the test group. The mean overlap in areas, measured by the Dice coefficient, was 11.5 ± 3.2% in the training group and 13.9 ± 4.6% in the test group.

CONCLUSION

A GCN can be trained to identify isthmus areas in SRRATs and may help identify critical ablation targets.

Efficacy of Commonly Used 3D Mapping Systems in Acute Success Rates of Catheter Ablation Procedures

Introduction: This systematic review aims to summarize the procedural arrhythmia termination rates in catheter ablation (CA) procedures of atrial or ventricular arrhythmias using the commonly used mapping systems (CARTO, Rhythmia and EnSite/NavX). Materials and Methods: A systematic search in MEDLINE and Cochrane databases through February 2021 was performed. Results: With regard to atrial fibrillation ablation procedures, acute success rates ranged from 15.4 to 96.0% and 9.1 to 100.0% using the CARTO and EnSite/NavX mapping systems, respectively; acute atrial tachycardia (AT) termination to sinus rhythm ranged from 75 to 100% using the CARTO system. The acute success rate for different types of AT ranged from 75 to 97% using Rhythmia, while the NavX mapping system was also found to have excellent efficacy in the setting of AT, with acute arrhythmia termination rates ranging from 73 to 99%. With regard to ventricular tachycardia, in the setting of ischaemic cardiomyopathy, acute success rates ranged from 70 to 100% using CARTO and 64% using EnSite/NavX systems. The acute success rate using the Rhythmia system ranged from 61.5 to 100.0% for different clinical settings. Conclusions: Mapping systems have played a crucial role in high-density mapping and the observed high procedural success rates of atrial and ventricular CA procedures. More data are needed for the comparative efficacy of mapping systems in acute arrhythmia termination, across different clinical settings.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Atrial Tachycardias After "Multiple" Previous Ablations for Tachyarrhythmias: Treatment by Anti-arrhythmic Drugs or Additional Ablation?

Pulmonary vein (PV) isolation (PVI) ablation as the first-line therapy for atrial fibrillation (AF) and repeat PVIs for patients who had symptomatic improvement with the index PVI but who develop AF recurrence are directed by practice guidelines. How many catheter ablation (CA) procedures constitute the definition of "multiple" ablations is not known. Whether atrial tachyarrhythmias (AF, atrial tachycardia [AT], atrial flutter [AFL]) that occur post-ablation are due entirely to the proarrhythmic effects of CA or a continuum of the arrhythmia spectrum from the underlying atriopathy is debatable. Herein, we describe a case of a 65-year-old man with a CHA2DS2-VASc score of 5 points who suffered from atrial tachyarrhythmias for which seven CA procedures were performed. Because of symptomatic and drug-refractory AT/AFL that failed cardioversions, he requested another ablation procedure. During the eighth procedure, high-density three-dimensional electroanatomic mapping, including Coherent and Ripple mapping (CARTO® 3; Biosense Webster, Diamond Bar, CA, USA), of AT/AFL was performed. Small discrete areas of relatively viable tissue within an extensively scarred left atrium and a macro-re-entrant circuit with early-meets-late activation between the left atrial anterior wall and the right superior PV were found. Radiofrequency ablation performed at this site resulted in the termination of the tachycardia, and bidirectional conduction block across the line was achieved. On clinical follow-ups and rhythm monitoring by an implantable loop recorder, the patient remained in sinus rhythm with significant clinical improvement. Our case suggests that, in patients with prior multiple CAs, additional clinically indicated ablation should be performed using high-density mapping to accurately identify arrhythmia mechanisms, elucidate the disease substrate, and restore the sinus rhythm successfully.

Characterization of durability and reconnection patterns at time of repeat ablation after single-shot pulsed field pulmonary vein isolation

BACKGROUND

Pulsed field ablation (PFA) is a novel method of cardiac ablation where there is insufficient knowledge on the durability and reconnection patterns after pulmonary vein isolation (PVI). The aim of this study was to characterize the electrophysiological findings at time of repeat procedure in real-world atrial fibrillation (AF) patients.

METHODS

Patients who underwent a repeat procedure (n=26) for symptomatic recurrent arrhythmias after index first-time treatment with single-shot PFA PVI (n=266) from July 2021 to June 2023 were investigated with 3D high-density mapping and ad-hoc re-ablation by radiofrequency or focal PFA.

RESULTS

Index indication for PVI was persistent AF in 17 (65%) patients. The mean time to repeat procedure was 292 ± 119 days. Of the 26 patients (104 veins), complete durable PVI was observed in 11/26 (42%) with a durable vein isolation rate of 72/104 (69%). Two patients (8%) had all four veins reconnected. The posterior wall was durably isolated in 4/5 (80%) of the cases. The predominant arrhythmia mechanism was AF in 17/26 (65%) patients and regular atrial tachycardia (AT) in 9/26 (35%). Reconnection was observed 9/26 (35%) in right superior, 11/26 (42%) in right inferior, 7/26 (27%) in left superior, 5/26 (19%) in left inferior, p=0.31 between veins. The gaps were significantly clustered in the right-sided anterior carina compared to other regions (P=0.009).

CONCLUSIONS

Durable PVI was observed in less than half of the patients at time of repeat procedure. No significant difference in PV reconnection pattern was observed, but the gap location was preferentially located at the anterior aspects of the right-sided PVs. Predominant recurrence was AF. More data is needed to establish lesion formation and durability and AT circuits after PFA.

Quantitative analysis of fractionated electrogram area of left atrium during right atrial pacing as an indicator of left atrial electrical remodeling in patients with atrial fibrillation

Background

The clinical significance of left atrial local electrogram fractionation after restoration of sinus rhythm in patients with atrial fibrillation (AF) has not been elucidated.

Methods

We evaluated ultrahigh-resolution maps of the left atrium (LA) during RA pacing acquired after pulmonary vein isolation in 40 patients with AF. The association between low-voltage area (LVA, <0.5 mV), fractionated electrogram area (FEA, the highlighted area with LUMIPOINT™ Complex Activation), the interval from onset of LA activation to wavefront collision at the mitral isthmus (LA activation time), and wave propagation velocity (WPV) was evaluated quantitatively.

Results

The total LVA, total FEA with ≥5.0 peaks or ≥7.0 peaks were 7.0 ± 7.9 cm2, 15.9 ± 12.9 cm2, and 5.2 ± 7.5 cm2, respectively. These areas were predominantly observed in the anteroseptal region. Total LVA, total FEA with ≥5.0 peaks, and total FEA with ≥5.0 peaks in the normal voltage area (NVA: ≥0.5 mV) correlated with LA activation time (R = 0.69, 0.75, and 0.71; each p < .0001). In the anterior wall, these areas correlated with regional mean WPV (R = -0.75, -0.83, and - 0.55; each p < .0001) and the extent of slow conduction area (SCA) with WPV <0.3 m/s (R = 0.89, 0.84, 0.33; p < .0001 for LVA and FEA, p < .05 for FEA located in NVA). The anterior wall FEA with ≥7.0 peaks and that in the NVA showed a better correlation in predicting anterior wall SCA (R = 0.92 and 0.86, each p < .0001).

Conclusion

Quantitative analysis of FEA together with LVA may facilitate the assessment of LA electrical remodeling.

Focal pulsed field ablation and ultrahigh-density mapping - versatile tools for all atrial arrhythmias? Initial procedural experiences

BACKGROUND

Focal pulsed field ablation (FPFA) is a novel and promising method of cardiac ablation. The aim of this study was to report the feasibility, short-term safety, and procedural findings for a broad spectrum of ablated atrial arrhythmias.

METHODS

Patients (n = 51) scheduled for ablation of atrial arrhythmias were prospectively included and underwent FPFA using the Galvanize CENTAURI generator with energy delivery through commercially available ablation catheters with ultrahigh-density (UHDx) 3D electroanatomic voltage/local activation time map evaluations. Workflow, procedural data, and peri-procedural technical errors and complications are described.

RESULTS

Planned ablation strategy was achieved with FPFA-only in 48/51 (94%) of the cases. Ablation strategy was first-time pulmonary vein isolation (PVI) in 17/51 (36%), repeat ablation in 18/51 (38%), PVI + in 13/51 (28%), and cavotricuspid isthmus block (CTI)-only in 3/51 (6%). The mean procedure time was 104 ± 31 min (first-time PVI), 114 ± 26 min (repeat procedure), 152 ± 36 min (PVI +), and 62 ± 17 min (CTI). Mean UHDx mapping time to assess lesion formation and block after ablation was 7 ± 4 min with 5485 ± 4809 points. First pass acute (linear) isolation with bidirectional block for anatomical lesion sets was 120/124 (97%) for all PVs, 17/17 (100%) for (any) isthmus, and 14/17 (82%) for left atrium posterior wall (LAPW). We observed several time-consuming integration errors with the used ablation system (mean 3.4 ± 3.7 errors/procedure), one transient inferior ST elevation when ablating CTI resolved by intravenous nitroglycerine and one transient AV block requiring temporary pacing for > 24 h.

CONCLUSIONS

FPFA was a highly versatile method to treat atrial arrhythmias with high first-pass efficiency. UHDx revealed acute homogenous low-voltage lesions in ablated areas. More data is needed to establish lesion durability and limitations of FPFA.

High density mapping of complex atrial tachycardia in patients after cardiac surgery

To provide an overview of the current application of high-density mapping (HDM) in the mechanism of complex atrial tachycardias (ATs). Complex ATs are frequently scar-related, after history of previous cardiac surgery and large scars. These scar-related ATs are difficult to manage medically and frequently recur after electrical cardioversion. HDM technologies have enabled rigorous elucidation of AT mechanisms in patients post cardiac surgery. This article showed the application of HDM technology in complex ATs from the mechanisms of complex ATs, the development of HDM technology, and the identification of scars or critical isthmus from HDM. HDM-guided approach is highly effective for identifying the ATs mechanism and critical isthmus.

High-density characterization of the sinus rhythm: a new functional substrate map of scar-related atrial tachycardia

BACKGROUND

Reentrant atrial tachycardias (ATs) utilize critical isthmus (CI) for the maintenance of the circuit. The electrophysiological characteristics and clinical implications of the targeted CI regions of reentrant ATs during sinus rhythm (SR) were not clear. Therefore, our research aims at studying the electrical properties of the CI sites for scar-related reentrant ATs and the functional substrate mapping identified during SR.

METHODS

Patients mapped with high-density catheters during SR and reentrant ATs were retrospectively analyzed. The CI regions of the reentrant ATs were confirmed by the combination of the activation map and the entrainment. The substrate mapping was analyzed for wavefront propagation, conduction velocity, and electrogram patterns.

RESULTS

Twenty patients with 22 reentrant ATs that underwent high-density maps were analyzed at 2 hospitals. Mapping performed during SR identified a scar region of 23.0 ± 13.6% of the left atrium. Regions of the CI in SR were characterized by low voltage (0.3 ± 0.2 mV), conduction slowing (0.4 ± 0.2 m/s), and fractionated electrogram (duration 62.5 ± 13.9 ms). Substrate mapping during SR showed that the regions of the CI located with the low-voltage zone in 16 out of 22 CI (72.7%), the deceleration zone in 15 out of 22 CI (68.2%), and late atrial activation in 12 out of 22 CI (54.5%). Targeting regions of CI achieve 94% of termination or change of the reentrant circuit. At 6.2 ± 7.1 months, there was 75% freedom from atrial arrhythmia.

CONCLUSIONS

Novel high-density mapping can identify the functional substrates during SR and guide ablation. Low-voltage areas with conduction slowing are putative predictors of the CI for the maintenance of the reentrant ATs.

Automated three-dimensional activation versus conventional mapping for catheter ablation of atrial tachycardia - A prospective randomized trial

Background

The automated NavX Ensite Precision latency-map (LM) algorithm aims to identify atrial tachycardia (AT) mechanisms. However, data on a direct comparison of this algorithm with conventional mapping are scarce.

Methods

Patients scheduled for AT ablation were randomized to mapping with the LM- algorithm (LM group) or to conventional mapping (conventional only group: ConvO), using entrainment and local activation mapping techniques. Several outcomes were exploratively analyzed. Primary endpoint was intraprocedural AT Termination. If AT termination with only automated 3D-Mapping failed, additional conventional methods were applied (conversion).

Results

A total of 63 patients (mean 67 years, 34 % female) were enrolled. In the LM group (n = 31), the correct AT mechanism was identified in 14 patients (45 %) using the algorithm alone compared to 30 patients (94 %) with conventional methods. Time to termination of the first AT was not different between groups (LM group 34 ± 20 vs. ConvO 43.1 ± 28.3 min; p = 0.2). However, when AT termination did not occur with LM algorithm, time to termination prolonged significantly (65 ± 35 min; p = 0.01). After applying conventional methods (conversion), procedural termination rates did not differ between LM group (90 %) vs. ConvO (94 %) (p = 0.3). During a follow-up time of 20 ± 9 months, no differences were observed in clinical outcomes.

Conclusion

In this small prospective, randomized study, the use of the LM algorithm alone may lead to AT termination, but less accurate than conventional methods.

Non-Iatrogenic Localized-Reentrant Figure of Eight Atrial Tachycardias in the Superior Vena Cava

Introduction

The superior vena cava (SVC) is an important non-pulmonary venous foci of atrial fibrillation (AF) and is known as the arrhythmogenic site of scar-related atrial tachycardia (AT). Scar-related ATs may occur after catheter ablation and open heart surgery; however, idiopathic AT rarely occurs. Case Presentation. A 77-year-old male with terminal diabetic nephropathy complained of dialysis-induced hypotension due to AF and was admitted to our hospital for catheter ablation. Here, we report a case of non-iatrogenic localized-reentrant figure of eight AT in the SVC.

Conclusion

SVC has the arrhythmogenic potential for re-entrant tachycardia, and the development of mapping technology can reveal arrhythmogenic mechanisms.

Utility and limitations of coherent mapping algorithm utilizing vectors and global propagation patterns in atrial tachycardia

Background

A novel mapping algorithm utilizing vectors and global patterns of propagation (Coherent™, Biosense Webster) has been developed to help identify the mechanism of atrial tachycardia (AT). We aimed to determine the diagnostic accuracy of coherent mapping compared with that of ripple mapping.

Methods and results

This study included 41 consecutive patients with 84 ATs (47 reentrant and 37 focal ATs). Two independent electrophysiologists confirmed the diagnoses using coherent mapping before the ripple map-guided ablation. AT termination was achieved in 75 of 84 ATs (89%) at first ablation lesion set. Four of the remaining nine ATs, which were terminated before an index radiofrequency (RF) application, were non-inducible after RF delivery at the first lesion set, whereas the other five ATs were terminated at the second lesion set. Diagnostic agreement between coherent and ripple maps was achieved in 51 of 84 ATs (61%): 28 of the 47 macroreentrant ATs (60%) and 23 of the 37 focal ATs (62%; P = 0.826). In typical macroreentrant ATs, including left atrial roof, perimitral, and cavotricuspid isthmus-dependent ATs, coherent maps achieved diagnostic agreement in 23 of 29 ATs (79%), which was higher than that in other ATs (51%, P = 0.018): 13 of 26 macroreentrant ATs (50%) and 15 of 29 focal ATs (52%, P = 1.000).

Conclusion

Ripple map-guided AT ablation achieved a high termination rate in the first lesion set. Coherent mapping yielded a favorable diagnostic accuracy for typical macroreentrant ATs, though its value for diagnosing other ATs was limited.

First clinical experience using a novel automated mapping algorithm for mapping of ventricular arrhythmias

A new automated vector-based mapping algorithm (AMA) for 3-dimensional (3D) mapping has been introduced. The aim of this study was to present our experience using AMA to recognize additional catheter ablation targets in patients with ventricular arrhythmias (VA). A total of 16 patients (ICM; ischemic cardiomyopathy, n = 6; NICM; non-ischemic cardiomyopathy n = 10) suffering from VA underwent catheter ablation. Following bipolar voltage mapping, AMA was utilized to reveal zones of decelerated conduction velocity vectors (CVV) and this information was superimposed onto the 3D reconstructions and compared with the presence of scar. Mapping time was 28.1 ± 10 min for the endocardial reconstruction of the left ventricle (LV) and 17 ± 5.4 min for the epicardium (n = 6 patients). The mean area of LV low voltage was 13.9 ± 15% (endocardial) and 11.9 ± 5.7% (epicardial). Decelerating CVV zones were revealed in all patients (mean conduction velocity threshold of 39.3 ± 13%). Sustained VA have been terminated through ablation and substrate modification was performed in all patients. Correlation between the presence of CVV deceleration zones and areas of abnormal low voltage from bipolar mapping was revealed in only 37.5% of patients, but there was good correlation between scar from unipolar voltage mapping and the presence of CCV deceleration zones (94%; p = 0.008). The novel AMA may improve the understanding of individual VA substrates due to the visualization of decelerated CVV zones and their correlation with abnormal low voltage predominantly from unipolar mapping.

Orientation of conduction velocity vectors on cardiac mapping surfaces

AIMS

Electroanatomical maps using automated conduction velocity (CV) algorithms are now being calculated using two-dimensional (2D) mapping tools. We studied the accuracy of mapping surface 2D CV, compared to the three-dimensional (3D) vectors, and the influence of mapping resolution in non-scarred animal and human heart models.

METHODS AND RESULTS

Two models were used: a healthy porcine Langendorff model with transmural needle electrodes and a computer stimulation model of the ventricles built from an MRI-segmented, excised human heart. Local activation times (LATs) within the 3D volume of the mesh were used to calculate true 3D CVs (direction and velocity) for different pixel resolutions ranging between 500 μm and 4 mm (3D CVs). CV was also calculated for endocardial surface-only LATs (2D CV). In the experimental model, surface (2D) CV was faster on the epicardium (0.509 m/s) compared to the endocardium (0.262 m/s). In stimulation models, 2D CV significantly exceeded 3D CVs across all mapping resolutions and increased as resolution decreased. Three-dimensional and 2D left ventricle CV at 500 μm resolution increased from 429.2 ± 189.3 to 527.7 ± 253.8 mm/s (P < 0.01), respectively, with modest correlation (R = 0.64). Decreasing the resolution to 4 mm significantly increased 2D CV and weakened the correlation (R = 0.46). The majority of CV vectors were not parallel (<30°) to the mapping surface providing a potential mechanistic explanation for erroneous LAT-based CV over-estimation.

CONCLUSION

Ventricular CV is overestimated when using 2D LAT-based CV calculation of the mapping surface and significantly compounded by mapping resolution. Three-dimensional electric field-based approaches are needed in mapping true CV on mapping surfaces.

Atrial conduction velocity mapping: clinical tools, algorithms and approaches for understanding the arrhythmogenic substrate

Characterizing patient-specific atrial conduction properties is important for understanding arrhythmia drivers, for predicting potential arrhythmia pathways, and for personalising treatment approaches. One metric that characterizes the health of the myocardial substrate is atrial conduction velocity, which describes the speed and direction of propagation of the electrical wavefront through the myocardium. Atrial conduction velocity mapping algorithms are under continuous development in research laboratories and in industry. In this review article, we give a broad overview of different categories of currently published methods for calculating CV, and give insight into their different advantages and disadvantages overall. We classify techniques into local, global, and inverse methods, and discuss these techniques with respect to their faithfulness to the biophysics, incorporation of uncertainty quantification, and their ability to take account of the atrial manifold.

Combination of High-Density and Coherent Mapping for Ablation of Ventricular Arrhythmia in Patients with Structural Heart Disease

The present study describes our experience with a new mapping approach for ventricular arrhythmia (VA) ablation in patients with structural heart disease (SHD). Consecutive patients undergoing catheter ablation for recurrent VA were analyzed. High-density mapping was conducted in all patients. In patients with inducible VA, local activation time (LAT) mapping and a novel vector-based mapping algorithm were implemented to analyze arrhythmia propagation. In case of focal tachycardia, the location of earliest activation was targeted. In VAs with re-entrant mechanisms, zones of slow conduction based on coherent mapping were ablated. Substrate modification was performed when pathologic electrograms were identified. Seventy-four patients were included. Sixty-five patients (87.8%) were male. Ischemic cardiomyopathy was the underlying disease in 35 patients (47.3%) and nonischemic cardiomyopathy was the underlying disease in 39 patients (52.7%). Mean left ventricular ejection fraction was 33.8 ± 9.9%. Non-inducibility of any VA was achieved in 70 patients (94.6%). Termination of VA was achieved in 93.5% of patients with stable VA. In 4 patients (5.4%), partial success was achieved. VA (p < 0.001), ATP (p < 0.001) and shock burden (p = 0.001) were significantly reduced after ablation. Mean arrhythmia-free survival after 12 months was 85.1 ± 4.7%. High-density mapping in combination with coherent mapping may facilitate the understanding of the tachycardia mechanism, providing targets for effective ablation.

Functional Assessment of Ventricular Tachycardia Circuits and Their Underlying Substrate Using Automated Conduction Velocity Mapping

OBJECTIVES

This study sought to describe the utility of automated conduction velocity mapping (ACVM) in ventricular tachycardia (VT) ablation.

BACKGROUND

Identification of areas of slowed conduction velocity (CV) is critical to our understanding of VT circuits and their underlying substrate. Recently, an ACVM called Coherent Mapping (Biosense Webster Inc) has been developed for atrial mapping. However, its utility in VT mapping has not been described.

METHODS

Patients with paired high-density VT activation and substrate maps were included. ACVM was applied to paired VT activation and substrate maps to assess regional CV and activation patterns. A combination of ACVM, traditional local activation time maps, electrogram analysis, and off-line calculated CV using triangulation were used to characterize zones of slowed conduction during VT and in substrate mapping.

RESULTS

Fifteen patients were included in the study. In all cases, ACVM identified slow CV within the putative VT isthmus, which colocalized to the VT isthmus identified with entrainment. The dimensions of the VT isthmus with local activation time mapping were 37.8 ± 13.7 mm long and 8.7 ± 4.2 mm wide. In comparison, ACVM produced an isthmus that was shorter (length: 25.1 ± 10.6 mm; mean difference: 12.8; 95% CI: 7.5-18.0; P < 0.01) and wider (width: 18.8 ± 8.1 mm; mean difference: 10.1; 95% CI: 6.1-14.2; P < 0.01). In VT, the CV using triangulation at the entrance (8.0 ± 3.6 cm/s) and midisthmus (8.1 ± 4.3 cm/s) was not significantly different (P = 0.92) but was significantly faster at the exit (16.2 ± 9.7 cm/s; P < 0.01). In the paired substrate analysis, traditional local activation time isochronal mapping identified 6.3 ± 2.0 deceleration zones. In contrast, ACVM identified a median of 0 deceleration zones (IQR: 0-1; P < 0.01).

CONCLUSIONS

ACVM is a novel complementary tool that can be used to accurately resolve complex VT circuits and identify slow conduction zones in VT but has limited accuracy in identifying slowed conduction during substrate-based mapping.

Preserved electrical conduction between donor and recipient right atria as the cause of macroreentrant atrial tachycardia after heart transplantation

Atrial arrhythmias after heart transplantation are common and usually originate from reentrant circuits inside the donor and recipient atria. A case is presented of macroreentrant atrial tachycardia with a reentry circuit incorporating preserved electrical conduction from the donor and recipient right atria. An invasive electrophysiological study including high-density electroanatomical mapping with a multipolar catheter was performed during tachycardia. A reentry circuit with an area of slow conduction at the supero-lateral aspect of the surgical anastomosis could be demonstrated. Catheter ablation at the site of slow conduction successfully terminated and permanently suppressed the tachycardia.

The utility of a novel mapping algorithm utilizing vectors and global pattern of propagation for scar-related atrial tachycardias

BACKGROUND

Activation maps of scar-related atrial tachycardias (AT) can be challenging to interpret due to difficulty in inaccurate annotation of electrograms, and an arbitrarily predefined mapping window. A novel mapping software integrating vector data and applying an algorithmic solution taking into consideration global activation pattern has been recently described (Coherent™, Biosense Webster "Investigational").

OBJECTIVE

We aimed to assess the investigational algorithm to determine the mechanism of AT compared with the standard algorithm.

METHODS

This study included patients who underwent ablation of scar-related AT using the Carto 3 and the standard activation algorithm. The mapping data were analyzed retrospectively using the investigational algorithm, and the mechanisms were evaluated by two independent electrophysiologists.

RESULTS

A total of 77 scar-related AT activation maps were analyzed (89.6% left atrium, median tachycardia cycle length of 273 ms). Of those, 67 cases with a confirmed mechanism of arrhythmia were used to compare the activation software. The actual mechanism of the arrhythmia was more likely to be identified with the investigational algorithm (67.2% vs. 44.8%, p = .009). In five patients with dual-loop circuits, 3/5 (60%) were correctly identified by the investigational algorithm compared to 0/5 (0%) with the standard software. The reduced atrial voltage was prone to lead to less capable identification of mechanism (p for trend: .05). The investigational algorithm showed higher inter-reviewer agreement (Cohen's kappa .62 vs. .47).

CONCLUSIONS

In patients with scar-related ATs, activation mapping algorithms integrating vector data and "best-fit" propagation solution may help in identifying the mechanism and the successful site of termination.

Mapping of an atrial tachycardia after Epicor™ high-intensity focused ultrasound ablation: A case report

BACKGROUND

Surgical techniques, such as the application of high-intensity focused ultrasound (HIFU), can be used for pulmonary vein isolation (PVI).

CASE SUMMARY

We report a case of a 73-year old patient, in whom HIFU failed to achieve PVI but promoted the occurrence of a scar-related atrial tachycardia (AT). Voltage mapping of the left atrium revealed multiple gaps along the ablation line. Coherent mapping with visualization of velocity vectors allowed the correct interpretation and the targeted ablation of the AT.

DISCUSSION

Cardiac surgery can promote scar-related AT. The coherent mapping function could simplify the mapping of scar-related AT in the future.

The isthmus characteristics of scar-related macroreentrant atrial tachycardia in patients with and without cardiac surgery

INTRODUCTION

Identifying the critical isthmus (CI) in scar-related macroreentrant atrial tachycardia (AT) is challenging, especially for patients with cardiac surgery. We aimed to investigate the electrophysiological characteristics of scar-related macroreentrant ATs in patients with and without cardiac surgery.

METHODS

A prospective study of 31 patients (mean age 59.4 ± 9.81 years old) with scar-related macroreentrant ATs were enrolled for investigation of substrate properties. Patients were categorized into the nonsurgery (n = 18) and surgery group (n = 13). The CIs were defined by concealed entrainment, conduction velocity less than 0.3 m/s, and the presence of local fractionated electrograms.

RESULTS

Among the 31 patients, a total of 65 reentrant circuits and 76 CIs were identified on the coherent map. The scar in the surgical group is larger than the nonsurgical group (18.81 ± 9.22 vs. 10.23 ± 5.34%, p = .016). The CIs in surgical group have longer CI length (15.27 ± 4.89 vs. 11.20 ± 2.96 mm, p = .004), slower conduction velocity (0.46 ± 0.19 vs. 0.69 ± 0.14 m/s, p < .001), and longer total activation time (45.34 ± 9.04 vs. 38.24 ± 8.41%, p = .016) than those in the nonsurgical group. After ablation, 93.54% of patients remained in sinus rhythm during a follow-up of 182 ± 19 days.

CONCLUSION

The characteristics of the isthmus in macroreentrant AT are diverse, especially for surgical scar-related AT. The identification of CIs can facilitate the successful ablation of scar-related ATs.

Three-dimensional visualization of bidirectional preferential pathway conduction of premature ventricular contractions originating from the outflow tract

INTRODUCTION

Preferential pathway conduction is mostly detected as fractionated presystolic-potentials preceding the QRS during premature ventricular contractions (PVCs) and late-potentials during sinus rhythm (SR), but the electrophysiologic mechanisms and significance of these potentials have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was three-dimensionally visualized.

METHODS

Five PVCs (two from the left coronary cusp, two from the commissure of the left and right coronary cusps, and one from the pulmonary artery) in four patients for which a fractionated presystolic-potential during the PVCs and late-potential during SR were recorded at the successful ablation site were reviewed, and three-dimensional coherent activation maps with the conduction velocity vector during the PVCs and SR were reconstructed.

RESULTS

At the successful ablation site, an "M"-shaped discrete presystolic-potential and "W"-shaped discrete late-potential were recorded in all patients. The configuration of the inverted electrogram of the presystolic-potential was similar to that of the electrogram exhibiting the late-potential. We created coherent activation maps annotating the onset of the presystolic-potentials during the PVCs and offset of the late-potentials during SR, which suggested bidirectional conduction of the preferential pathway connecting the PVC origin to the myocardium.

CONCLUSION

Detailed activation mapping of these PVCs is consistent with the presence of fibers along the aortic or pulmonic valve ring that have preferential directions for conduction. PVCs produce a presystolic-potential. In SR, the fiber is activated late and from the opposite direction, producing an inverted potential inscribed on the end of the QRS.

[Coherent mapping in adults with congenital heart disease : Role of the novel coherent mapping technique for treatment of atrial tachycardia in adults with congenital heart disease]

A 31-year-old woman with a surgically corrected double outlet right ventricle and recurrent narrow QRS complex tachycardia was admitted to our hospital. The patient was scheduled for electrophysiology study. Coherent mapping identified the critical isthmus as a slow conduction area within posterolateral intercaval scar tissue. A continuous line of ablation was applied resulting in termination of the atrial tachycardia at the site of the critical isthmus from coherent mapping. Thus, coherent mapping facilitates complex ablation procedures and improves efficacy and efficiency.

Identification of critical isthmus using coherent mapping in patients with scar-related atrial tachycardia

INTRODUCTION

Accurate identification of slow conducting regions in patients with scar-related atrial tachycardia (AT) is difficult using conventional electrogram annotation for cardiac electroanatomic mapping (EAM). Estimating delays between neighboring mapping sites is a potential option for activation map computation. We describe our initial experience with CARTO 3 Coherent Mapping (Biosense Webster Inc,) in the ablation of complex ATs.

METHODS

Twenty patients (58 ± 10 y/o, 15 males) with complex ATs were included. We created three-dimensional EAMs using CARTO 3 system with CONFIDENSE and a high-resolution mapping catheter (Biosense Webster Inc). Local activation time and coherent maps were used to aid in the identification of conduction isthmus (CI) and focal origin sites. System-defined slow or nonconducting zones and CI, defined by concealed entrainment (postpacing interval < 20 ms), CV < 0.3 m/s and local fractionated electrograms were evaluated.

RESULTS

Twenty-six complex ATs were mapped (mean: 1.3 ± 0.7 maps/pt; 4 focal, 22 isthmus-dependent). Coherent mapping was better in identifying CI/breakout sites where ablation terminated the tachycardia (96.2% vs 69.2%; P = .010) and identified significantly more CI (mean/chamber 2.0 ± 1.1 vs 1.0 ± 0.7; P < .001) with narrower width (19.8 ± 10.5 vs 43.0 ± 23.9 mm; P < .001) than conventional mapping. Ablation at origin and CI sites was successful in 25 (96.2%) with long-term recurrence in 25%.

CONCLUSIONS

Coherent mapping with conduction velocity vectors derived from adjacent mapping sites significantly improved the identification of CI sites in scar-related ATs with isthmus-dependent re-entry better than conventional mapping. It may be used in conjunction with conventional mapping strategies to facilitate recognition of slow conduction areas and critical sites that are important targets of ablation.