Direct Comparison of Point-by-Point and Rapid Ultra-High-Resolution Electroanatomical Mapping in Patients Scheduled for Ablation of Atrial Fibrillation

A novel wide-band dielectric imaging system to guide radiofrequency ablation for pulmonary vein isolation

INTRODUCTION

Recently, the wide-band dielectric mapping system Kodex-EPD was introduced. This study reports the first clinical experience using a novel system to guide pulmonary vein isolation (PVI) with radiofrequency (RF) ablation. METHODS AND RESULTS: The study included 20 consecutive patients undergoing de-novo PVI for symptomatic paroxysmal or persistent atrial fibrillation guided by Kodex-EPD. The primary efficacy endpoint was successful PVI. Secondary endpoints included procedural parameters and complications. In all 20 patients (mean age 68 ± 8 years, 12 male patients, paroxysmal fibrillation in 14/20 [70%] patients), PVI was successfully completed. One patient underwent additional cavo-tricuspid isthmus ablation for concomitant typical atrial flutter and one patient required additional ablation of a focal atrial tachycardia. A conventional three-dimensional image of the left atrium as well as the innovative endocardial panoramic view were used to guide catheter manipulation and ablation. Median procedure time was 115 [1st; 3rd quartile 93,75; 140] min and median total fluoroscopy time was 9.9 [9.7; 11.2] min, of which a median of 0.8 [0.6; 0.9] min was required to create left atrial maps. Complete left atrial imaging using Kodex-EPD was achieved within a median of 7.1 [5.7; 8.3] min. Median RF ablation time was 45.1 [34.6; 58.7] min. No major complications were observed.

CONCLUSION

RF ablation PVI guided by Kodex-EPD seems safe and feasible. The system provides effective three-dimensional guidance for PVI.

[Rhythm and metabolic control]

Diabetes mellitus and atrial fibrillation show a steady increase in their prevalence. Diabetes mellitus is a relevant risk factor for the development and maintenance of atrial fibrillation, which should not be underestimated. Fluctuations in blood glucose levels occurring in diabetes, inflammatory processes and oxidative stress lead to structural, electromechanical, electrical and autonomic remodelling processes in the myocardium that promote atrial fibrillation. When atrial fibrillation and diabetes mellitus coincide, this is often associated with more pronounced symptoms, lower quality of life, more frequent hospitalization and a higher mortality rate. Can early and consistent euglycemic blood glucose monitoring effectively influence atrial remodelling processes, cardiovascular end points and the occurrence of atrial fibrillation? Are there new and combined drug treatment approaches for diabetes mellitus and atrial fibrillation? What ablation strategy should be adopted for the interventional treatment of atrial fibrillation in patients with diabetes mellitus? This review article attempts to find answers to these questions.

Performance and acute procedural outcomes of the EnSite Precision™ cardiac mapping system for electrophysiology mapping and ablation procedures: results from the EnSite Precision™ observational study

Background

The EnSite Precision™ cardiac mapping system (Abbott) is a catheter navigation and mapping system capable of displaying the three-dimensional (3D) position of conventional and sensor-enabled electrophysiology catheters, as well as displaying cardiac electrical activity as waveform traces and dynamic 3D maps of cardiac chambers. The EnSite Precision™ Observational Study (NCT-03260244) was designed to quantify and characterize the use of the EnSite Precision™ cardiac mapping system for mapping and ablation of cardiac arrhythmias in a real-world environment and evaluate procedural outcomes.

Methods

A total of 1065 patients were enrolled at 38 centers in the USA and Canada between 2017 and 2018 and were followed for 12 months post procedure for arrhythmia recurrence, medication use, and quality-of-life changes. Eligible subjects were adults undergoing a cardiac electrophysiology mapping and radiofrequency ablation procedure using the EnSite Precision™ System.

Results

A final cohort of 925 patients (64.3 years of age, 30.2% female) were analyzed. The primary procedural indication was atrial flutter in 48.1% (445/925), atrial fibrillation in 46.5% (430/925), and other arrhythmias in 5% (50/925). Electroanatomic mapping was performed in 81.5% (754/925) of patients. Mapping was stable throughout 79.8% (738/925) of procedures with initial mapping time of 8.6 min (IQR 4.7–15.0). Average mapping efficiency created with AutoMap or TurboMap was 164.9 ± 365.7 used points per minute. Median number of mapping points collected and used was 1752.5 and 811.0, respectively. Only 335/925 (36.2%) required editing and 66.0% (221/335) of these patients required editing of less than 10 points. Fluoroscopy was utilized in most cases (n = 811/925, 87.4%) with fluoroscopy time of 11.0 min (IQR 6.0–18.0). Overall median procedure time was 101.0 min (IQR 59.0–152.0). Acute procedural success was high for both atrial fibrillation (n = 422/430, 98.1%) and atrial flutter (n = 434/445, 97.5%).

Conclusion

In a real-world study analysis, use of the EnSite Precision™ mapping system was associated with high procedural stability, short mapping times, high point density requiring infrequent editing, low fluoroscopy time, and high prevalence of acute procedural success.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-022-01239-4.

Atrial fibrillation and cardiac fibrosis

The understanding of atrial fibrillation (AF) evolved from a sole rhythm disturbance towards the complex concept of a cardiomyopathy based on arrhythmia substrates. There is evidence that atrial fibrosis can be visualized using late gadolinium enhancement cardiac magnetic resonance imaging and that it is a powerful predictor for the outcome of AF interventions. However, a strategy of an individual and fibrosis guided management of AF looks promising but results from prospective multicentre trials are pending. This review gives an overview about the relationship between cardiac fibrosis and AF focusing on translational aspects, clinical observations, and fibrosis imaging to emphasize the concept of personalized paths in AF management taking into account the individual amount and distribution of fibrosis.

Anatomical targets and expected outcomes of catheter-based ablation of atrial fibrillation in 2020

Anatomical-based approaches, targeting either pulmonary vein isolation (PVI) or additional extra PV regions, represent the most commonly used ablation treatments in symptomatic patients with atrial fibrillation (AF) recurrences despite antiarrhythmic drug therapy. PVI remains the main anatomical target during catheter-based AF ablation, with the aid of new technological advances as contact force monitoring to increase safety and effective radiofrequency (RF) lesions. Nowadays, cryoballoon ablation has also achieved the same level of scientific evidence in patients with paroxysmal AF undergoing PVI. In parallel, electrical isolation of extra PV targets has progressively increased, which is associated with a steady increase in complex cases undergoing ablation. Several atrial regions as the left atrial posterior wall, the vein of Marshall, the left atrial appendage, or the coronary sinus have been described in different series as locations potentially involved in AF initiation and maintenance. Targeting these regions may be challenging using conventional point-by-point RF delivery, which has opened new opportunities for coadjuvant alternatives as balloon ablation or selective ethanol injection. Although more extensive ablation may increase intraprocedural AF termination and freedom from arrhythmias during the follow-up, some of the targets to achieve such outcomes are not exempt of potential severe complications. Here, we review and discuss current anatomical approaches and the main ablation technologies to target atrial regions associated with AF initiation and maintenance.

[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.

An initial experience of high-density mapping-guided ablation in a cohort of patients with adult congenital heart disease

Aims

In the management of both ventricular and supraventricular tachycardia in patients with congenital heart disease (CHD) catheter ablation has now been recognized as one of the mainstays.

Methods and results

We review our initial experience of using the Rhythmia mapping system in a cohort of 12 adult CHD patients presenting with multiple arrhythmia substrates. A total of 78 arrhythmia maps were attempted in a total of 15 procedures, but possible due to the dilatation of the target chamber only 44% of maps were able to reconstruct the entire arrhythmia. All patients underwent pre-procedure 3D imaging (either cardiac magnetic resonance or computed tomography), but image integration was suboptimal. A median of two maps per patient were finally analysed and acquisition took in median 22 min with a median number of 12 574 (8230–18 167) mapping points. Procedural data with a total duration amounting to in median 285 (194–403) min, with a median total fluoroscopy exposure of 7.5 (5.2–10.7) min. After a median of 1.5 procedures [median of 12 (8–16 months)], nine patients remained in stable sinus rhythm or atrial paced rhythm, while three patients had further sustained recurrences. One of these passed away in end-staged heart failure.

Conclusion

This initial experience of using high-density mapping for arrhythmia management in patients with CHD allowed rapid acquisition of multiple maps with high accuracy to identify surgical scars and fibrosis, however, it was limited by large atrial volumes and a high percentage of incomplete maps resulting in modest clinical success.

Basket catheter-guided ultra-high-density mapping of cardiac arrhythmias: a systematic review and meta-analysis

Aim: Ultra-high-density mapping (HDM) is increasingly used for guidance of catheter ablation in cardiac arrhythmias. While initial results are promising, a systematic evaluation of long-term outcome has not been performed so far. Methods: A systematic review and meta-analysis was conducted on studies investigating long-term outcome after Rhythmia HDM-guided atrial fibrillation (AF) or atrial tachycardia catheter ablation. Results: Beyond multiple studies providing novel insights into arrhythmia mechanisms, follow-up data from 17 studies analyzing Rhythmia HDM-guided ablation (1768 patients, 49% with previous ablation) were investigated. Cumulative acute success was 100/90.2%, while 12 months long-term pooled success displayed at 71.6/71.2% (AF/atrial tachycardia). Prospective data are limited, showing similar outcome between HDM-guided and conventional AF ablation. Conclusion: Acute results of HDM-guided catheter ablation are promising, while long-term success is challenged by complex arrhythmogenic substrates. Prospective randomized trials investigating different HDM-guided ablation strategies are warranted and underway.

Catheter Ablation of Atrial Fibrillation: State of the Art and Future Perspectives

PURPOSE OF REVIEW

Atrial fibrillation (AF), the most common sustained arrhythmia, is associated with high rates of morbidity and mortality. Maintenance of stable sinus rhythm (SR) is the intended treatment target in symptomatic patients, and catheter ablation aimed at isolating the pulmonary veins provides the most effective treatment option, supported by encouraging clinical outcome data. A variety of energy sources and devices have been developed and evaluated. In this review, we summarize the current state of the art of catheter ablation of AF and describe future perspectives.

RECENT FINDINGS

Catheter ablation is a well-established treatment option for patients with symptomatic AF and is more successful at maintaining SR than antiarrhythmic drugs. Antral pulmonary vein isolation (PVI) as a stand-alone ablation strategy results in beneficial clinical outcomes and is therefore recommended as first-line strategy for both paroxysmal and persistent AF. While radiofrequency-based PVI in conjunction with a three-dimensional mapping system was for many years considered to be the "gold standard", the cryoballoon has emerged as the most commonly used alternative AF ablation tool, especially in patients with paroxysmal AF. Patients with persistent or long-standing persistent AF and with arrhythmia recurrence after previous PVI may benefit from additional ablation strategies, such as substrate modification of various forms or left atrial appendage isolation. New technologies and techniques, such as identification of the AF sources and magnetic resonance imaging-guided substrate modification, are on the way to further improve the success rates of catheter ablation for selected patients and might help to further reduce arrhythmia recurrence.

CONCLUSIONS

Pulmonary vein isolation is the treatment of choice for symptomatic patients with paroxysmal and persistent drug-refractory AF. The reconnection of previously isolated pulmonary veins remains the major cause of AF recurrence. Novel ablation tools, such as balloon technologies or alternative energy sources, might help to overcome this limitation. Patients with non-paroxysmal AF and with AF recurrence might benefit from alternative ablation strategies. However, further studies are warranted to further improve our knowledge of the underlying mechanisms of AF and to obtain long-term clinical outcomes on new ablation techniques.

How, When, and Why: High-Density Mapping of Atrial Fibrillation

High-density (HD) mapping presents opportunities to enhance delineation of atrial fibrillation (AF) substrate, improve efficiency of the mapping procedure without sacrificing safety, and afford new mechanistic insights regarding AF. Innovations in hardware, software algorithms, and development of novel multielectrode catheters have allowed HD mapping to be feasible and reliable. Patients to particularly benefit from this technology are those with paroxysmal AF in setting of preexisting atrial scar, persistent AF, and AF in the setting of complex congenital heart disease. The future will bring refinements in automated HD mapping including evolution of noncontact methodologies and artificial intelligence to supplant current techniques.

Cardiac Mapping Systems: Rhythmia, Topera, EnSite Precision, and CARTO

Novel cardiac mapping systems allow a safe and highly accurate 3-D reconstruction of cardiac structures as well as fast and accurate visualization of cardiac arrhythmias. In addition, they are increasingly reducing the need for fluoroscopy in these procedures. The current state of the art, as well as the presentation of possible uses of individual systems and their limitations, is presented in this article. Cardiac mapping systems can significantly contribute to an optimal therapeutic decision making in invasive electrophysiology. This article introduces new developments of Rhythmia, Topera, EnSite Precision, and CARTO systems and provides a look ahead to the future.

Missing pouches in high-density mapping of atrial tachyarrhythmia in congenital heart diseases

BACKGROUND

The use of high-density electroanatomical mapping in the Chinese population for congenital heart disease (CHD) is not well reported.

METHODS

Retrospective review of consecutive transcatheter ablation of atrial tachyarrhythmia using high-density mapping for CHD patients (at least moderate complexity) in the only tertiary congenital heart center in the territory from January 2017 to January 2019 was conducted. Orion mapping catheter in Rhythmia system (Boston Scientific) was used to create activation and voltage maps. Parameters including mechanism of arrhythmia, acute success, and follow-up data were recorded.

RESULTS

Eight patients were identified (median age 35.5 years) who underwent transcatheter ablation of atrial arrhythmia. More than one reentry circuits of IART were identified in five patients. It took a median of 32.4 minutes with 15,952 (IQR 13,395-18,530) mapping points per map. Cavo-annulus isthmus-dependent mechanism was the predominant reentry mechanism. Acute success with the elimination of all inducible tachycardia was achieved in six patients (75%), and partial success in two patients. There was recurrence of atrial arrhythmia in four patients (50%), in which three patients could be maintained in sinus rhythm with low-dose antiarrhythmic medication. Targeted substrate ablation was performed in six patients with multiple IART circuits. Critical anatomical pouches were identified in three patients, which were missed in the initial mapping using Orion basket mapping catheter.

CONCLUSIONS

High acute success rate of atrial arrhythmia ablation can be achieved using high-density anatomical mapping in CHD. Substrate ablation was required with multiple IART circuits identified. Vigilance should be sought to identify anatomical pouches.

Impact of mapping points in high-density mapping of the left atrium

PURPOSE

Currently, high-density mapping techniques are being discussed for more precise voltage mapping, lesion validation after pulmonary vein isolation (PVI) and superior left atrial tachycardia (LAT) mapping. However, the quality of high-density maps varies according to different mapping systems, multipolar catheter (MPC) types and numbers of mapping points. The aim of this study was to evaluate the impact of different numbers of mapping points in high-density mapping on validity.

METHODS

From February 2016 to August 2018, 154 patients with previous PVI ablation and recurrent atrial fibrillation (AF) or left atrial tachycardia (LAT) were mapped by Orion™ multipolar catheter and Rhythmia HDx™ mapping system at our centre. Of those, 90 maps from 25 patients [11 male patients/14 female patients; age 76 ± 12 years] with 8000 to 16,000 mapping points in the primary map were collected. All maps were evaluated offline by two independent and blinded electrophysiologists regarding the following issues: (1) Is PVI observable in all veins? (2) Does voltage map cover the whole left atrium? (3) Does activation map display one or more isthmuses? The 90 maps consist of 30 maps with deactivated 24 of 64 electrodes of MPC with < 1000 mapping points (A), 30 maps with deactivated 16 of 64 electrodes of MPC and 2000 to 6000 mapping points (B) and 30 primary maps with 8000 to 16,000 mapping points (C).

RESULTS

For (A), only in one map (3.3%), for (B) in 20 maps (66.7%, p < 0.05) and for (C) in 24 maps (80%) both investigators agreed with evaluable PVI in all veins. Investigators were able to assess whether the voltage map covered the whole left atrium and the same low voltage areas in (A) in 0 maps, in (B) in 16 maps (53%, p < 0.05) and in (C) in 23 maps (77%, p < 0.05). Also, investigators were able to locate the same critical isthmuses in the activation maps in (A) in 0 maps, in (B) in 2 maps (7%) and in (C) in 20 maps (67%, p < 0.05).

CONCLUSIONS

In order to achieve comparable high-density maps which are verified by independent investigators, a minimum of 2000 to 6000 mapping points are required in the majority of voltage maps to evaluate PVI and low voltage areas. To define the critical isthmuses in activations maps, 8000 mapping points or more might be necessary. High-density maps with more than 8000 points increase the interrater reliability.

Advanced mapping strategies for ablation therapy in adults with congenital heart disease

Background

Ultra-high density mapping (HDM) is a promising tool in the treatment of patients with complex arrhythmias. In adults with congenital heart disease (CHD), rhythm disorders are among the most common complications but catheter ablation can be challenging due to heterogenous anatomy and complex arrhythmogenic substrates. Here, we describe our initial experience using HDM in conjunction with novel automated annotation algorithms in patients with moderate to great CHD complexity.

Methods

We studied a series of consecutive adult patients with moderate to great CHD complexity and an indication for catheter ablation due to symptomatic arrhythmia. HDM was conducted using the Rhythmia™ mapping system and a 64-electrode mini-basket catheter for identification of anatomy, voltage, activation pattern and critical areas of arrhythmia for ablation guidance. To investigate novel advanced mapping strategies, postprocedural signal processing using the Lumipoint™ software was applied.

Results

In 19 patients (53±3 years; 53% male), 21 consecutive ablation procedures were conducted. Procedures included ablation of atrial fibrillation (n=7; 33%), atrial tachycardia (n=11; 52%), atrioventricular accessory pathway (n=1; 5%), the atrioventricular node (n=1; 5%) and ventricular arrhythmias (n=4; 19%). A total of 23 supraventricular and 8 ventricular arrhythmias were studied with the generation of 56 complete high density maps (atrial n=43; ventricular n=11, coronary sinus n=2) and an average of 12,043±1,679 mapping points. Multiple arrhythmias were observed in n=7 procedures (33% of procedures; range of arrhythmias detected 2-4). A total range of 1-4 critical areas were defined per procedure and treated within a radiofrequency application time of 16 (interquartile range 12-45) minutes. Postprocedural signal processing using Lumipoint™ allowed rapid annotation of fractionated signals within specific windows of interest. This supported identification of a practical critical isthmus in 20 out of 27 completed atrial and ventricular tachycardia activation maps.

Conclusions

Our findings suggest that HDM in conjunction with novel automated annotation algorithms provides detailed insights into arrhythmia mechanisms and might facilitate tailored catheter ablation in patients with moderate to great CHD complexity.

Comparison of ablation outcomes of the second ablation procedure for recurrent atrial fibrillation using an ultra-high-resolution mapping system and conventional mappings system

Background

The utility of an ultra‐high‐resolution electroanatomical mapping system (UHR‐EAM, Rhythmia) for repeat atrial fibrillation (AF) ablation has not been evaluated.

Hypothesis

A second AF ablation procedure performed using UHR‐EAM may demonstrate different outcomes compared with that using a conventional electroanatomical mapping system (C‐EAM, CARTO3).

Method

This observational study enrolled consecutive patients who underwent a second AF ablation procedure using UHR‐EAM (n = 103) and C‐EAM (n = 153). The second ablation procedure included re‐isolation of reconnected pulmonary veins (PVs) and elimination of clinical or induced non‐PV AF triggers and atrial tachycardia (AT). Other empirical ablations were additionally conducted at the discretion of the operators.

Results

Re‐isolation of PVs was achieved in 196 patients who had ≥1 left atrial‐PV reconnection. The elimination rate of AT was higher in the UHR‐EAM group than the C‐EAM group (87% vs 65%, P = .040), while that of non‐PV AF triggers was similar (63% vs 63%, P = 1.00). The UHR‐EAM demonstrated shorter radiofrequency application time (21.8 ± 16.8 vs 28.0 ± 21.3 minutes, P = .017), but longer fluoroscopic time (26.2 ± 12.6 vs 21.4 ± 9.3 minutes, P = .0001). No severe complication developed. The total 1‐year AF/AT‐free survival rates were similar between the two groups (off AADs, 59.2% vs 56.2%, P = .62; on AADs, 65.0% vs 69.3%, P = .49).

Conclusion

The efficacy and safety outcomes of repeat AF ablation using UHR‐EAM was comparable to those using C‐EAM.

Ultra-rapid high-density mapping system with the phase singularity technique is feasible in identifying rotors and focal sources and predicting AF termination

INTRODUCTION

Phase singularity (PS) mapping provides additional insight into the AF mechanism and is accurate in identifying rotors. The study aimed to evaluate the feasibility of PS mapping in identifying AF rotors using data obtained from an automatic ultra-rapid high-resolution mapping system with a high-density mini-basket catheter.

METHODS

Twenty-three pigs underwent rapid right atrial (RA) pacing (RAP 480 bpm) for 5 weeks before the experiment. During AF, RA endocardial automatic continuous mappings with a mini-basket catheter were generated using an automatic ultra-rapid mapping system. Both fractionation mapping and waveform similarity measurements using a PS mapping algorithm were applied on the same recording signals to localize substrates maintaining AF.

RESULTS

Seventeen (74%) pigs developed sustained AF after RAP. Three were excluded because of periprocedural ventricular arrhythmia and corrupted digital data. RA fractionation maps were acquired with 6.17 ± 4.29 minutes mean acquisition time, 13768 ± 12698 acquisition points mapped during AF from 581 ± 387 beats. Fractionation mapping identified extensively distributed (66.7%) RA complex fractionated atrial electrogram (CFAE), whereas the nonlinear analysis identified high similarity index (SI > 0.7) parts in limited areas (23.7%). There was an average of 1.67 ± 0.87 SI sites with 0.43 ± 0.76 rotor/focal source/chamber. AF termination occurred in 11/16 (68.75%) AF events in 14 pigs during ablation targeting max CFAE. There was a higher incidence of rotor/focal source at AF termination sites compared with non-AF termination sites (54.5% vs 0%, P = 0.011).

CONCLUSIONS

The data obtained from ultra-rapid high-density automatic mapping is feasible and effective in identifying AF rotors/focal sources using PS technique, and those critical substrates were closely related to AF procedural termination.

Comparison between novel and standard high-density 3D electro-anatomical mapping systems for ablation of atrial tachycardia

Ultra-high-density mapping allows very accurate characterization of circuits/mechanisms in atrial tachycardia (AT). Whether these advantages will translate into a better procedural or long-term clinical outcome is unknown. Sixty consecutive AT ablation procedures using ultra-high-density mapping (Rhythmia™, group 1) were retrospectively compared to 60 consecutive procedures using standard high-density mapping (Carto/NavX™, group 2) (total 209 AT, 79% left AT). A higher number of maps were performed in group 1 (4.8 ± 2.5 vs 3.2 ± 1.7, p = 0.0001) with similar acquisition duration (12 ± 5 vs 13 ± 6 min per map, p = ns), although with a greater number of activation points (10,543 ± 5854 vs 689 ± 1827 per map, p < 0.0001). AT location remained undetermined in 5 AT in group 1 vs 10 (p = 0.1). Mechanism remained undetermined in 5 AT from group 1 vs 11 (p = 0.06). Acute complete success was achieved in 77%, in both groups. At 1-year follow-up, AT recurred in 37% in group 1 vs 50% in group 2 (p = 0.046). There are less long-term recurrences after AT ablation using ultra-high-density mapping system compared to standard high-density 3D mapping, possibly because of a better comprehensive approach of AT mechanisms.

[High-resolution 3D mapping : Opportunities and limitations of the Rhythmia™ mapping system]

Three-dimensional mapping systems are used for the characterization and treatment of complex arrhythmias, such as atrial reentrant tachycardias, atrial fibrillation, or ventricular tachycardia. The Rhythmia™ mapping system (Boston Scientific, Natick, MA, USA) belongs to a novel generation of mapping systems that are able to rapidly create high-density and high-resolution three-dimensional maps in an automated manner. Mapping is performed with a magnetic- and impedance-based tracked bidirectional deflectable 64-pole basket catheter (IntellaMap Orion™, Boston Scientific). Based on previous studies, the system is effective and safe for the treatment of complex atrial and ventricular arrhythmias.

Initial single centre experience with the novel Rhythmia© high density mapping system in an all comer collective of 400 electrophysiological patients

BACKGROUND

A novel, automatically annotating ultra-high density mapping system (Rhythmia©, Boston Scientific) collects a high number and quality of electrograms (EGMs). So far, data on general use in the electrophysiological laboratory are sparse.

METHODS

We retrospectively analyzed all our ablations using Rhythmia and recorded patient clinical data, procedural parameters, and mapping parameters including the count of EGMs, mapping time, and mapping volume. Where appropriate, procedural parameters were compared over time to assess a learning curve.

RESULTS

400 patients underwent ablation of atrial fibrillation (n = 202), typical (n = 16) or atypical atrial flutter (n = 49), VT (n = 48), PVC (n = 35), accessory pathways (n = 14), AVNRT (n = 4), and focal atrial tachycardia (n = 32). System use was feasible, as no procedure had to be stopped for technical reasons and no ablation had to be withheld because of mapping failure, and safe, with an overall complication rate of 2.25%. Initial restrictions in manoeuvrability of the mapping catheter were overcome rapidly, as indicated by a significant decrease of fluoroscopy time (20 vs. 14 min, p = 0.02), use of contrast agent (50 vs. 40 ml; p < 0.01), and (not significant) lower procedure times (194 vs. 170 min; p = 0.12; comparing the first with the last third of patients undergoing pulmonary vein isolation only procedure). Ablation of complex left atrial, focal and ventricular tachycardias benefited from the reliable automatic annotation of a high number of EGMs.

CONCLUSION

The use of the Rhythmia is feasible and safe. Initial restrictions in manoeuvrability of the Orion mapping catheter were overcome rapidly. The procedures that benefit the most from ultra-high density mapping are complex left atrial tachycardias, focal tachycardias, and ventricular tachycardias.

[Mapping and ablation of cardiac arrhythmias : Never forget where you are coming from]

With the rapid development of new mapping and imaging technologies as well as catheter ablation technologies, it is increasingly important to understand the basic concepts of conventional mapping and ablation of cardiac arrhythmias. Prerequisite for successful ablation is the exact identification of the tachycardia mechanism and subsequent localization of the origin or tachycardic substrate. Only intracardiac electrograms provide decisive information regarding activation time and signal morphology. In some arrhythmias, it is necessary to supplement conventional mapping with so-called pace and/or entrainment mapping. This article aims to discuss and demonstrate the fundamentals of intracardiac mapping as it relates to the mapping and ablation of supraventricular and ventricular arrhythmias based on representative clinical cases. Modern three-dimensional mapping methods make it possible to individually optimize established ablation strategies with significantly better spatial resolution. The authors aimed to demonstrate that intracardiac uni- and bipolar electrograms provide essential information about timing and morphology guiding successful catheter ablation. Furthermore, our article provides useful information about conventional cardiac mapping techniques including activation mapping, pace mapping, and individual substrate mapping.

Catheter Ablation for Atrial Fibrillation in Adults With Congenital Heart Disease: Lessons Learned From More Than 10 Years Following a Sequential Ablation Approach

OBJECTIVES

This study aimed to evaluate the impact, safety, and success of atrial fibrillation (AF) ablation in adults with congenital heart disease (ACHD) transferring ablation strategies established in normal hearts.

BACKGROUND

AF is an emerging arrhythmia in ACHD.

METHODS

Fifty-seven consecutive ACHD (median age 51.1 ± 14.8 years) with drug-refractory AF were analyzed who underwent catheter ablation between 2004 and 2017. CHD was classified according to its complexity into mild (61.4%), moderate (17.5%), and severe (21.1%) lesions. AF ablation was performed in 104 procedures following a sequential ablation approach.

RESULTS

Of the 57 patients, 30 underwent corrective surgery, 6 underwent palliative surgery, 5 had catheter interventions, and 16 were natural survivors. Follow-up was available for all patients (median 41 ± 36 months). The median duration of cyanosis was 9.2 ± 19.7 years, and the time of volume or pressure overload prior to corrective surgery or intervention was 26.1 ± 21.2 years and 18.1 ± 15.8 years, respectively. The Kaplan-Meier estimate for arrhythmia-free survival following the index ablation procedure was 63% for 1 year and 22% for 5 years. Performing subsequent ablation procedures (2.0 ± 0.5), the Kaplan-Meier estimate significantly improved, with 99% for 1 year and 83% for 5 years (p < 0.01). Five patients died during follow-up due to their underlying CHD condition or underwent transplantation.

CONCLUSIONS

AF ablation strategies established in normal hearts can be transferred to ACHD. The treatment is safe and effective with acceptable long-term results. Varying anatomical pre-conditions and the heterogeneous population itself are challenging and contribute toward a higher reablation rate. Therefore, AF ablation in ACHD should be reserved for dedicated and highly specialized teams.

The identification of conduction gaps after pulmonary vein isolation using a new electroanatomic mapping system

BACKGROUND

The reconnection of left atrial-pulmonary vein (LA-PV) conduction after the initial procedure of pulmonary vein (PV) isolation is not rare, and is one of the main cause of atrial fibrillation (AF) recurrence after PV isolation.

OBJECTIVE

We investigated feasibility of a new ultrahigh-resolution mapping system using a 64-pole small basket catheter for the identification of LA-PV conduction gaps.

METHODS

This prospective study included 31 consecutive patients (20 with persistent AF) undergoing a second ablation after a PV isolation procedure with LA-PV reconnected conduction at any of the 4 PVs. An LA-PV map was created using the mapping system, and ablation was performed at the estimated gap location.

RESULTS

The propagation map identified 54 gaps from 39 ipsilateral PV pairs, requiring manual electrogram reannotation for 23 gaps (43%). Gaps at the anterior and carinal regions of left and right ipsilateral PVs required manual electrogram reannotation more frequently than the other regions. The voltage map could identify the gap only in 19 instances (35%). Electrophysiological properties of the gaps (multiple gaps in the same ipsilateral PVs, conduction time, velocity, width, and length) did not differ between those needing and not needing manual electrogram reannotation. During the gap ablation, either the activation sequence alteration or elimination of PV potentials was observed using a circular catheter placed in the PV, suggesting that all the identified gaps were correct.

CONCLUSION

This new electroanatomic mapping system visualized all the LA-PV gaps in patients undergoing a second AF ablation.