Evaluation of Electrophysiological Mechanisms of Post-Surgical Atrial Tachycardias Using an Automated Ultra-High-Density Mapping System

Charge density mapping demonstrates superiority in catheter ablation of post-surgical atrial tachycardias

Introduction

Atrial tachycardia (AT) frequently occurs after cardiac surgery or surgical ablation procedures. The novel charge density-based mapping system (CDM) provides global chamber mapping and can detect crucial pathways of conduction; therefore, it has potential added value in catheter ablation (CA) of post-surgical ATs. We aimed to test the hypothesis that CDM-guided CA procedures are safe, feasible, and may improve outcome compared to conventional sequential 3D mapping (CARTO)-based CA.

Methods and results

Consecutive patients undergoing CA for post-surgical AT guided by CDM or CARTO were enrolled. Procedural safety and efficiency were analyzed. Acute success, one-year outcome was assessed. A total of 35 patients (mean age 60.8 ± 10.6 years, 42.9% female) underwent CA of AT using CDM (n = 20) and CARTO (n = 15). A total of 61 ATs were mapped (35 in CDM and 26 in CARTO group). Four patients had focal ATs, 22 macro re-entrant, and 8 patients had ATs with both mechanisms. No differences were found in procedural complication (CDM 3 vs. CARTO 1 patient, p = 0.61). There were no differences in procedure duration (185.9 vs. 147.9 min, p = 0.09), fluoroscopy dose (165.0 vs. 155.0 mGy, p = 0.31), RF application number (28.0 vs. 18.0, p = 0.17) or duration (1,251.5 vs. 1,060.0 s, p = 0.54). Acute success was 95.0% in CDM and 73.3% in CARTO group (p = 0.14). Cumulative AT recurrence rates were lower in CDM group compared to CARTO group (10.0% vs. 46.7%, p = 0.02).

Conclusions

The CDM system is feasible. Our data suggest that patients treated with CDM-guided CA developed fewer AT recurrences as compared to CARTO-guided procedures.

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.

Treatment of Atrial Tachycardia Arising after Superior Transseptal Approach Mitral Valve Surgery: Insights from Ultra High-Density Mapping to Prevent Atrioventricular Block

INTRODUCTION

Mitral valve surgery employing a superior transseptal approach (STA) is associated with arrhythmogenicity and intra-atrial conduction delay, despite being optimal for visualization of the surgical field. It is sometimes difficult to treat atrial tachycardias (AT) that arise after STA. To investigate AT circuits that arise after STA in detail in order to identify the optimal ablation line, using ultra high-resolution mapping (UHRM).

METHODS

We retrospectively analyzed 12 AT from 10 patients (median age 70 years, 9 males) who had undergone STA surgery. The tachycardias were mapped using the Rhythmia mapping system (Boston Scientific, Natick, Massachusetts).

RESULTS

The 12 STA-related AT (STA-AT) circuits were classifiable as follows according to location of the optimal ablation line: (1) peri-septal incision STA-AT (n = 3), (2) cavotricuspid isthmus dependent STA-AT (n = 7) and (3) biatrial tachycardia (n = 2). Radiofrequency (RF) application terminated 11 of the 12 STA-AT. We found that difference in STA-AT circuit type was due to characteristics of the septal incision line made for STA. UHRM was important in identifying optimal ablation sites that did not create additional conduction disturbances in the right atrium.

CONCLUSIONS

ATs after STA involve complex arrhythmia circuits due to multiple and long incision lines in the right atrium. Accurate understanding of the arrhythmia circuit and sinus conduction in the right atrium after STA is recommended for treating post-surgical tachycardia in a minimally invasive manner. This article is protected by copyright. All rights reserved.

Single-center experience of ultra-high-density mapping guided catheter ablation of focal atrial tachycardia

Introduction

Catheter ablation is the treatment of choice for recurrent focal atrial tachycardia (FAT) as medical therapy is limited. Routinely, a three‐dimensional mapping system is used. Whether or not optimized signal detection does improve ablation success rates has not yet been investigated. This retrospective cohort study compared ablation procedures using an ultra‐high‐density mapping system (UHDM, Rhythmia, Boston Scientific) with improved signal detection and automatic annotation with procedures using a conventional electroanatomic mapping system (CEAM, Biosense Webster, CARTO).

Methods

All patients undergoing ablation for FAT using UHDM or CEAM from April 2015 to August 2018 were included. Endpoints comprised procedural parameters, acute success as well as freedom from arrhythmia 12 months after ablation.

Results

A total of 70 patients underwent ablation (48 with UHDM, 22 with CEAM). No significant differences were noted for parameters like procedural and radiation duration, area dose, and RF applications. Acute success was significantly higher in the UHDM cohort (89.6% vs. 68.2%, p = .03). Nevertheless, arrhythmia freedom 12 months after ablation was almost identical (56.8% vs. 60%, p = .87), as more patients with acute success of ablation presented with a relapse during follow‐up (35.0 vs. 7.7%, p = .05).

Conclusion

Acute success rate of FAT ablation might be improved by UHDM, without an adverse effect on procedural parameters. Nevertheless, further research is needed to understand the underlying mechanism for increased recurrence rates after acute successful ablation.

Ripple mapping-guided atrial tachycardia ablation following open-heart surgery

Ripple mapping can make the visualization of activation conduction on a 3-dimensional voltage map and is useful tool for scar-related organized atrial tachycardia (AT). This study sought to assess the efficacy of ripple mapping for interpreting reentrant circuits and critical isthmus in postoperative ATs. 34 consecutive patients with a history of mitral valve surgery (mean age, 54.5 ± 12.4 years) underwent high density (HD) RM during ATs with CARTO3v4 CONFIDENSE system. The voltage activation threshold was determined by RM over a bipolar voltage map. The identification of underlying mechanisms and ablation setting was based on RM without reviewing activation mapping. A total of 41 ATs (35 spontaneous, 6 induced) were characterized. 39 reentry circuits were successfully mapped (cycle length, 256 ± 43 ms). Of the 41 ATs, 28 were confirmed by ripple mapping alone (68%), and 12 (29%) by ripple mapping and entrainment mapping. Of 12 ATs in the left atrium, 9 (75%) needed entrainment to confirm, compared with 5 (17.8%) in the right atrium. Primary endpoint after initial ablation set was achieved in 32 of the 34 patients (94.1%). Freedom from atrial arrhythmias was 79.4% after the follow-up of 12 ± 5 months. Of the seven patients with recurrence, three underwent the repeated catheter ablation. Ripple mapping precisely delineated reentrant circuits in post-cardiac surgery AT resulting in a high success rate of ablation. Entrainment maneuvers remain useful for elucidation of complex AT circuits.

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.

High density mapping and catheter ablation of atrial tachycardias in adults with congenital heart disease

AIMS

We used a new grid-style multi-electrode mapping catheter (Advisor™ HD Grid, Abbott) and investigated its use for high density mapping of atrial tachycardias in adult patients with congenital heart disease.

PATIENTS AND METHODS

All patients with congenital heart disease who had mapping of atrial tachycardias using the new grid-style catheter between March 2018 and April 2019 were included.

RESULTS

A total of 24 adult patients had high density mapping of atrial tachycardias using the grid-style multi-electrode catheter. Mean procedure duration was 207 ± 72 min., mean fluoroscopy time was 7.1 ± 7.9 min. In patients with right atrial substrates, fluoroscopy time was shorter compared to biatrial or left atrial substrates (0.9 ± 2.2 min for right atrial substrates, n = 19 vs. 6.3 ± 8.3 min for left atrial substrates, n = 2 and 7.5 ± 4.3 min for biatrial substrates, n = 3, p = 0.01). A mean number of 14.814 ± 10.140 endocardial points were collected and 2.319 ± 1244 points were finally used to characterize the tachycardia. Procedural success was achieved in 21/24 (88%) subjects and partial success in 2/24 (8%) patients. Recurrence rate was low (12.5%). In one patient, radiofrequency ablation within the cavotricuspid isthmus resulted in occlusion of a branch of the right coronary artery. No complications related to the use of the mapping catheter itself occurred.

CONCLUSION

High density mapping of AT using the grid-style catheter showed promising results with respect to procedural and midterm outcome and fluoroscopy time. Using the grid-style catheter might offer advantages compared to other multi-electrode catheters used for high density mapping of AT in patients with CHD.

[Catheter ablation of supraventricular tachycardia]

Supraventricular tachycardias (SVT) are common, with atrioventricular nodal reentry tachycardias (AVNRT) being the most common paroxysmal supraventricular tachycardia. The pathophysiological understanding and the catheter ablation of SVTs have developed steadily in recent years. For example, dividing AVNRT into "typical" and "atypical" depending on the HA-, VA-interval and AH/HA ratio is recommended. Because of higher rates of recurrences after cryoablation, radiofrequency ablation has prevailed in AVNRT. The current ESC guidelines for SVTs recommend the ablation of accessory pathways in asymptomatic high-risk patients and it is now a Class I recommendation. There is no recommendation for the access in left-sided accessory pathways. However, a transseptal compared to transaortic approach seems more promising in acute success. The use of a three-dimensional (3D) mapping system leads to a reduction of the fluoroscopy times and procedure duration. Ablation of focal atrial tachycardia remains challenging despite the use of 3D electroanatomical mapping systems. However, new technologies such as high-density (HD) multipoint mapping systems can be helpful. HD mapping systems also allow a better understanding of left and right atrial macroreentry tachycardia after previous ablation or cardiac surgery and in primary nature. However, in all technological advances, a proficient understanding of the basic techniques in electrophysiology, such as entrainment mapping, is mandatory.

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.

High-resolution/Density Mapping in Patients with Atrial and Ventricular Arrhythmias

High-definition/ultra-high-definition mapping, owing to an impressive increase of the point density of electroanatomic maps, provides improved substrate characterization, better understanding of the arrhythmia mechanism, and a better selection of the ablation target in patients with atrial and ventricular arrhythmias. Despite the scarce comparative data on ablation results versus standard mapping, ultra-high-definition mapping is increasingly used by the electrophysiology community.