Left atrial tachycardia after circumferential pulmonary vein ablation for atrial fibrillation

Direct Epicardial Mapping and Ablation Revealing Three-Dimensional Roof-Dependent Macroreentrant Atrial Tachycardia Breaking Into Bachmann's Bundle

Catheter ablation for macroreentrant atrial tachycardia (AT) that recurs after atrial fibrillation (AF) ablation is occasionally difficult because of epicardial connections. Here, we report the case of a patient who underwent ablation for recurrent AT after AF ablation. Endocardial mapping of the left atrium (LA) showed a centrifugal pattern from the base of the appendage, and the LA roof showed discontinuous activation from the posterior LA. Direct epicardial mapping was performed, revealing the roof-dependent macroreentrant AT using the epicardial connection from the LA posterior to the Bachmann bundle. The entrainment pacing from the exit site of the epicardium was within the tachycardia circuit, and epicardial ablation successfully terminated the AT. Epicardial mapping and ablation can improve the procedural success rate of reentrant AT recurrence after endocardial ablation.

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, 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.

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 .

Right atrial tachycardia after atrial fibrillation ablation: prevalence, clinical characteristics, electrophysiological mechanisms, and long-term outcomes

BACKGROUND

This study aims to evaluate the prevalence, clinical characteristics, electrophysiological mechanisms, and long-term outcomes of right atrial tachycardia (AT) in patients who underwent ablation for atrial fibrillation (AF).

METHODS

From March 2010 to December 2020, 220 consecutive patients undergoing index AF ablation were referred for post-ablation AT recurrence. Thirty-five patients (35/220, 15.9%) with right AT recurrence (25 men; mean age 59.3 ± 10.2 years) were enrolled. These patients were divided into groups with right ATs exclusively (group 1) and right combined with left ATs (group 2).

RESULTS

Fifty-three ATs were mapped in all patients, with thirty-nine ATs originating from the right atrium. The detailed distribution of all right ATs was 22 in the cavo-tricuspid isthmus (CTI), 6 in the ostium of superior vein cava (SVC), 4 in the right free wall, 4 in the right anterior atrial septum, 2 in coronary sinus ostium, and 1 in crista terminalis. Group 2 had a significantly higher incidence of typical atrial flutter (AFL) than group 1 (11/12, 90.9% vs. 12/24, 50.0%, P = 0.03). During the mean follow-up of 43.6 ± 25.2 months after the index AT ablation, the recurrence rate of AT/AF was 22.9% (8/35), and it was lower in group 1 than in group 2 (8.3% vs. 54.5%, P = 0.01).

CONCLUSION

Right AT is relatively less common post-AF ablation. The CTI-dependent AFL and the ostium of SVC-derived focal AT constituted the major components of right ATs, suggesting the importance of ablation- and anatomy-related arrhythmogenic effects in the right atrium.

Outcomes of catheter ablation of atrial tachyarrhythmia guided exclusively by activation mapping

INTRODUCTION

Complex atrial tachyarrhythmias (CATs) are commonly observed in patients with prior catheter ablation or cardiac surgery. These arrhythmias are challenging to map and ablate. Historically, entrainment mapping was utilized to characterize CAT. With the advent of high-definition mapping (HDM), full visualization of the CAT circuit is possible which may obviate the need for entrainment mapping.

METHODS

We sought to investigate the outcomes of catheter ablation of CAT guided only by HDM. Consecutive patients who underwent CAT ablation from 2017 to 2021 were included in our study (excluding right atrial tachyarrhythmias). Patients were sorted by the type of mapping performed. Group I consisted of patients where HDM alone was utilized with no attempt of entrainment. Group II consisted of patients where both entrainment and HDM were utilized.

RESULTS

A total of 67 patients were included in our study, with 40 patients in HDM group (I) and 27 patients in entrainment group (II). No statistically significant difference regarding 1-year freedom from atrial arrhythmias was found between the two groups (80% vs 77.8%, p = 0.819). Four CATs were terminated by entrainment during procedure versus none in the HDM-only group (p = 0.011).

CONCLUSIONS

CAT ablation with HDM alone yielded similar 1-year freedom from atrial arrhythmias compared to ablation with HDM and entrainment. Entrainment combined with HDM was associated with higher undesired CAT interruption rate. Further validation is needed with randomized control trials.

Organization of atrial fibrillation using a pure sodium channel blocker: Implications of rotor ablation therapy

Background

Rotors are the source of atrial fibrillation (AF). However, the ablation of rotors for persistent AF is challenging. The purpose of this study was to identify the dominant rotor by accelerating the organization of AF using a sodium channel blocker and detecting the rotor's preferential area that governs AF.

Methods

Overall, 30 consecutive patients with persistent AF who underwent pulmonary vein isolation and still sustained AF were enrolled. Pilsicainide 50 mg was administered. An online real-time phase mapping system (ExTRa Mapping™) was used to identify the meandering rotors and multiple wavelets in 11 left atrial segments. The time ratio of non-passive activation (%NP) was evaluated as the frequency of rotor activity in each segment.

Results

Conduction velocity became slower-from 0.46 ± 0.14 to 0.35 ± 0.14 mm/ms (p = .004)-and the rotational period of the rotor was significantly prolonged-156 ± 21 to 193 ± 28 ms/cycle (p < .001). AF cycle length was prolonged from 169 ± 19 to 223 ± 29 ms (p < .001). A decrease in %NP was observed in seven segments. Additionally, 14 patients had at least one complete passive activation area. Of them, the use of high %NP area ablation resulted in atrial tachycardia and sinus rhythm in two patients each.

Conclusions

A sodium channel blocker organized persistent AF. In selective patients with a wide organized area, high %NP area ablation could convert AF into atrial tachycardia or terminate AF.

Characterization of temporal electrical activity patterns for detection of critical isthmus regions of recurrent atypical atrial flutter

INTRODUCTION

Identifying the critical isthmus region (CIR) of atrial re-entry tachycardias (AT) is challenging. The Lumipoint® (LP) software, developed for the Rhythmia® mapping system, aims to facilitate the successful ablation of ATs by identifying the CIR.

OBJECTIVE

The objective of this study was to evaluate the quality of LP regarding the percentage of arrhythmia-relevant CIR in patients with atypical atrial flutter (AAF).

METHODS

In this retrospective study, we analyzed 57 AAF forms. Electrical activity (EA) was mapped over tachycardia cycle length resulting in a two-dimensional EA pattern. The hypothesis was that EA minima suggest potential CIRs with slow-conduction-zone.

RESULTS

A total of n = 33 patients were included, with the majority of patients being already preablated (69.7%). LP algorithm identified a mean of 2.4 EA minima and 4.4 suggested CIRs per AAF form. Overall, we observed a low probability of identifying only the relevant CIR (POR) at 12.3% but a high probability that at least one CIR is detected (PALO) at 98.2%. Detailed analysis revealed EA minima depth (≤20%) and width (>50 ms) as the best predictors of relevant CIRs. Wide minima occurred rarely (17.5%), while low minima were more frequently present (75.4%). Minima depth of EA ≤ 20% showed the best PALO/POR overall (95% and 60%, respectively). Analysis in recurrent AAF ablations (five patients) revealed that CIR in de novo AAF was already detected by LP during the index procedure.

CONCLUSION

The LP algorithm provides an excellent PALO (98.2%), but poor POR (12.3%) to detect the CIR in AAF. POR improved by preselection of the lowest and widest EA minima. In addition, there might be the role of initial bystander CIRs becoming relevant for future AAFs.

Stacked machine learning models to classify atrial disorders based on clinical ECG features: a method to predict early atrial fibrillation

OBJECTIVES

Atrial Tachycardia (AT) and Left Atrial Enlargement (LAE) are atrial diseases that are significant precursors to Atrial Fibrillation (AF). There are ML models for ECG classification; clinical features-based classification is required. The suggested work aims to create stacked ML models that categorize Sinus Rhythm (SR), Sinus Tachycardia (ST), AT, and LAE signals based on clinical parameters for AF prognosis.

METHODS

The classification was based on thirteen clinical parameters, such as amplitude, time domain ECG aspects, and P-Wave Indices (PWI), such as the ratio of P-wave length and amplitude ((P (ms)/P (µV)), P-wave area (µV*ms), and P-wave terminal force (PTFV1(µV*ms). Apart from classifying the ECG signals, the stacked ML models prioritized the clinical features using a pie formula-based technique.

RESULTS

The Stack 1 model achieves 99% accuracy, sensitivity, precision, and F1 score, while the Stack 2 model achieves 91%, 91%, 94%, and 92% for identifying SR, ST, LAE, and AT, respectively. Both stack models obtained a computational time of 0.06 seconds. PTFV1 (µV*ms), P (ms)/P (µV)), and P-wave area (µV*ms) were ranked as crucial clinical features.

CONCLUSION

Clinical feature-based stacking ML models may help doctors obtain insight into important clinical ECG aspects for early AF prediction.

The ridge line of left pulmonary vein isolation from left atrial appendage can subsequently increase the completion rate of the mitral isthmus block line

BACKGROUND AND OBJECTIVES

Mitral isthmus (MI) ablation for mitral flutter is technically difficult, and incomplete block line is not uncommon. The objective of this study is to investigate the effect of the ridge line of left pulmonary vein isolation (LPVI) from left atrial appendage (LAA) on completion rate of mitral isthmus (MI) block line and recurrence rate of atrial tachycardia (AT) or atrial flutter (AFL) after the first MI ablation.

METHODS

We identified 611 patients who underwent first MI ablation for mitral flutter during the study period. Finally, 559 patients were enrolled and divided into two groups according to the method of ridge line ablation of LPVI (LAA group, n = 467, conventional group, n = 92). Outcome measures were the completion of MI block line by first MI ablation, the recurrence of AT/AFL, and repeat MI ablation after the first MI ablation.

RESULTS

The first MI block line completion rate was significantly higher in the LAA group than the conventional group (95% vs. 85%, p < 0.001). The recurrence rate of AT/AFL after 3 months from first MI ablation was significantly lower in the LAA group. The requirement of additional MI ablation tended to be lower in the LAA group.

CONCLUSIONS

Our novel approach of ablating LPV-LAA ridge from the LAA side during PVI can increase the success rate of MI block line completion, and reduce the recurrence rate of AT/AFL and the need for additional MI block line ablation. Graphical abstract Ablation of the left pulmonary vein-left atrial appendage ridge from the left atrial appendage side during PVI increased the success rate of mitral isthmus block line completion.

Interpretation of Typical and Atypical Atrial Flutters by Precision Electrocardiology Based on Intracardiac Recording

Atrial flutter is a term encompassing multiple clinical entities. Clinical manifestations of these arrhythmias range from typical isthmus-dependent flutter to post-ablation microreentries. Twelve-lead electrocardiogram (ECG) is a diagnostic tool in typical flutter, but it is often unable to clearly localize atrial flutters maintained by more complex reentrant circuits. Electrophysiology study and mapping are able to characterize in fine details all the components of the circuit and determine their electrophysiological properties. Combining these 2 techniques can greatly help in understanding the vectors determining the ECG morphology of the flutter waveforms, increasing the diagnostic usefulness of this tool.

Patterns and Characteristics of SKYLINE-Lumipoint Feature in the Catheter Ablation of Atypical Atrial Flutter: Insight from a Novel Lumipoint Module of Rhythmia Mapping System

Background: Atypical atrial flutter (aAFL) is not uncommon, especially after a prior cardiac surgery or extensive ablation in atrial fibrillation (AF). Aims: To revisit aAFL, we used a novel Lumipoint algorithm in the Rhythmia mapping system to evaluate tachycardia circuit by the patterns of global activation histogram (GAH, SKYLINE) in assisting aAFL ablation. Methods: Fifteen patients presenting with 20 different incessant aAFL, including two naïve, six with a prior AF ablation, and seven with prior cardiac surgery were studied. Results: Reentry aAFL in SKYLINE typically was a multi-deflected peak with 1.5 GAH-valleys. Valleys were sharp and narrow-based. Most reentry aAFL (18/20, 90%) lacked a plateau and displayed a steep GAH-valley with 2 GAH-valleys per tachycardia. Each GAH-valley highlighted 1.9 areas in the map. Successful sites of ablation all matched one of the highlighted areas based on GAH-valleys < 0.4. These sites corresponded with the areas highlighted by GAH-score < 0.4 in reentry aAFL, and by GAH-score < 0.2 in localized-reentry aAFL. Conclusions: The present study showed benefits of the LumipointTM module applied to the RhythmiaTM mapping system. The results were the efficient detection of the slow conduction, better identification of ablation sites, and fast termination of the aAFL with favorable outcomes.

Wide area circumferential ablation for pulmonary vein isolation using radiofrequency versus laser balloon ablation

Background

Persistent atrial fibrillation (AF) is associated with high recurrence rates of AF and atypical atrial flutters or tachycardia (AFT) postablation. Laser balloon (LB) ablation of the pulmonary vein (PV) ostia has similar efficacy as radiofrequency wide area circumferential ablation (RF-WACA); however, an approach of LB wide area circumferential ablation (LB-WACA) may further improve success rates.

Objective

To evaluate freedom from atrial tachyarrhythmia (AFT/AF) recurrence postablation using RF-WACA versus LB-WACA in persistent AF patients.

Methods

This was a retrospective multicenter study. Patients were followed for up to 24 months via office visits, Holter, and/or device monitoring. The primary endpoint was freedom from AFT/AF after a single ablation procedure. Secondary endpoints included freedom from AF, freedom from AFT, first-pass isolation of all PVs, and procedural complications.

Results

Two hundred and four patients were studied (LB-WACA: n = 103; RF-WACA: n = 101). Patients' baseline characteristics were similar except patients in the RF-WACA group were older (64 vs. 68, p = .03). First-pass isolation was achieved more often during LBA (LB-WACA: 88% vs. RF-WACA 75%; p = .04). Procedure (p = .36), LA dwell (p = .41), and fluoroscopy (p = .44) time were similar. The mean follow-up was 506 ± 279 days. Sixty-six patients had arrhythmic events including 24 AFT and 59 AF recurrences. LB-WACA group had higher arrhythmia-free survival (p = .009) after single ablation procedures. In the multivariate Cox regression model, RF-WACA was associated with a higher recurrence of AFT compared with LB-WACA (Adjusted HR 3.16 [95% CI: 1.13-8.83]; p = .03).

Conclusions

LB-WACA was associated with higher freedom from atrial arrhythmias mostly driven by the lower occurrence of AFT compared with RF-WACA.

Hybrid machine learning to localize atrial flutter substrates using the surface 12-lead electrocardiogram

Aims

Atrial flutter (AFlut) is a common re-entrant atrial tachycardia driven by self-sustainable mechanisms that cause excitations to propagate along pathways different from sinus rhythm. Intra-cardiac electrophysiological mapping and catheter ablation are often performed without detailed prior knowledge of the mechanism perpetuating AFlut, likely prolonging the procedure time of these invasive interventions. We sought to discriminate the AFlut location [cavotricuspid isthmus-dependent (CTI), peri-mitral, and other left atrium (LA) AFlut classes] with a machine learning-based algorithm using only the non-invasive signals from the 12-lead electrocardiogram (ECG).

Methods and results

Hybrid 12-lead ECG dataset of 1769 signals was used (1424 in silico ECGs, and 345 clinical ECGs from 115 patients—three different ECG segments over time were extracted from each patient corresponding to single AFlut cycles). Seventy-seven features were extracted. A decision tree classifier with a hold-out classification approach was trained, validated, and tested on the dataset randomly split after selecting the most informative features. The clinical test set comprised 38 patients (114 clinical ECGs). The classifier yielded 76.3% accuracy on the clinical test set with a sensitivity of 89.7%, 75.0%, and 64.1% and a positive predictive value of 71.4%, 75.0%, and 86.2% for CTI, peri-mitral, and other LA class, respectively. Considering majority vote of the three segments taken from each patient, the CTI class was correctly classified at 92%.

Conclusion

Our results show that a machine learning classifier relying only on non-invasive signals can potentially identify the location of AFlut mechanisms. This method could aid in planning and tailoring patient-specific AFlut treatments.

Spectrum of arrhythmogenic substrate post minimally invasive maze surgery in patients with recurrent

BACKGROUND

Advancements in minimally invasive surgical ablation (MISA) have focused on improving pulmonary vein isolation. Additional ablation targets have been developed (such as posterior wall isolation). The mid- and long-term effects of current techniques (including electrophysiologic findings and recurrent arrhythmia mechanisms) have not previously been reported.

METHODS

Twenty eight patients with recurrent atrial arrhythmias after bipolar clamp ablation of the pulmonary vein antrum, ganglionated plexi, posterior wall isolation (roof and floor lines to create a posterior box), and ligament of Marshall ligation/cauterization and left atrial appendage clipping underwent follow up electrophysiology study including left atrial mapping an average of 2.3 years postoperatively.

RESULTS

Atrial fibrillation was the most common recurrent arrhythmia (n = 18) followed by micro-reentrant atrial tachycardia (n = 5), macro-reentry left atrial flutter (n = 3), and typical cavo-tricuspid isthmus atrial flutter (n = 2). Eighty six of 112 (77%) PVs mapped were electrically isolated, 16 (57%) patients had all four pulmonary veins (PVs) isolated. The posterior wall (PW) was completely isolated in only four (14%) patients, seven (25%) patients had normal PW voltage, while 17 (61%) patients had abnormal delayed or fractionated electrograms in the posterior wall (incomplete isolation). Abnormal PW electrograms were more frequently found in patients with complex recurrent left atrial arrhythmia (micro-reentry or left atrial macro-reentry flutter).

CONCLUSION

With current surgical techniques PV isolation has improved, but PW isolation remains challenging. Incomplete PW isolation may produce arrhythmogenic substrate.

The effect of posterior wall isolation for persistent atrial fibrillation on recurrent arrhythmia

INTRODUCTION

It is important to consider recurrent arrhythmia after catheter ablation for persistent atrial fibrillation (AF) for planning an ablation strategy. However, the studies are limited to pulmonary vein isolation (PVI) plus posterior wall isolation (PWI), which were reported to improve procedural outcomes. The objective of this study is to evaluate the effect of PWI on recurrent arrhythmia.

METHODS

This is an observational study on patients with persistent AF comparing PVI plus PWI and PVI only strategies. In PVI plus PWI group, linear ablation of the left atrium roofline and bottom line were performed to achieve PWI after PVI. Some patients with AF recurrence underwent the second procedure. The presence of recurrent arrhythmia and results of the second procedures were evaluated.

RESULTS

A total of 181 patients (mean age, 66.9 ± 10.2 years; male, 76.8%) were included. PVI plus PWI group and PVI only group consisted of 90 and 91 patients, respectively. AF recurrence was observed in 28 of 90 (31.1%) patients with PVI plus PWI and in 43 of 91 (47.3%) with PVI only, and log-rank test did not show any significant difference (p = .35). The occurrence of recurrent persistent AF was significantly lower in PVI plus PWI group than in PVI only group (5/90; 5.6% vs. 18/91; 20.9%, p = .002). There was no significant difference between the two groups in recurrent paroxysmal AF and atrial tachycardia (AT).

CONCLUSION

PWI, in addition to PVI, for persistent AF was significantly related to fewer episodes of recurrent persistent AF, and it did not increase recurrent AT.

Catheter ablation for atrial tachycardias: How to interpret the unclear activation map?

BACKGROUND

Post-ablation atrial tachycardias (ATs) are characterized by low-voltage signals that challenge current mapping methods. In this study, we analyzed common mistakes during activation mapping and delineated a mapping strategy for correct interpretation of tachycardia mechanisms in patients with challenging underlying substrate.

METHODS AND RESULTS

Thirty-one patients referred for AT ablation were selected for the study. Three types of incorrect activation patterns were identified, which were referred to as unrecognized block line (pseudo-macroreentry and pseudo-fig-8 reentry), incorrect activation timing window of interest (WOI) (chaotic activation), and mis-annotation of complex signals (multiple sites of "early meets late"). Pseudo-macroreentry and chaotic activation occur in focal or localized reentry AT with the error related to the WOI selection (four cases), incorrect annotation of local activation time (six cases), or a previous line of atrial block in (seven cases). Pseudo-fig-8 reentry (five cases) and multiple sites of "early meets late" (nine cases) occur in macroreentrant AT with blocked areas and low-voltage atrial substrate. All ATs were successfully eliminated at the origin site.

CONCLUSIONS

We delineated a series of ATs in the setting of a disordered pattern of activation mapping encountered in patients after previous extensive ablation or atriotomy. The algorithm proposed rapidly corrects the activation map and identifies the mechanism of the AT.

Is the mid-diastolic isthmus always the best ablation target for re-entrant atrial tachycardias?

AIMS

We evaluated the ability of an ultrahigh mapping system to identify the most convenient Rhythmia ablation target (RAT) in intra-atrial re-entrant tachycardias (IART) in terms of the narrowest area to transect to interrupt the re-entry.

METHODS

A total of 24 consecutive patients were enrolled with a total of 26 IARTs. The Rhythmia mapping system was used to identify the RAT in all IARTs.

RESULTS

In 18 cases the RAT matched the mid-diastolic phase of the re-entry whereas in 8 cases the RAT differed. In these patients, the mid-diastolic tissue in the active circuit never represented the area with the slowest conduction velocity of the re-entry. The mean conduction velocity at the mid-diastolic site was significantly slower in the group of patients in which the RAT matched the mid-diastolic site (P = 0.0173) and that of the remaining circuit was significantly slower in the group in which the RAT did not match (P = 0.0068). The mean conduction velocity at the RAT was comparable between the two groups (P = 0.66).

CONCLUSION

Identifying the RAT in challenging IARTs by means of high-density representation of the wavefront propagation of the tachycardia seems feasible and effective. In one-third of cases this approach identifies an area that differs from the mid-diastolic corridor.

Atrial Tachycardias After Atrial Fibrillation Ablation: How to Manage?

With catheter ablation becoming effective for non-pharmacological management of AF, many cases of atrial tachycardia (AT) after AF ablation have been reported in the past decade. These arrhythmias are often symptomatic and respond poorly to medical therapy. Post-AF-ablation ATs can be classified into the following three categories: focal, macroreentrant and microreentrant ATs. Mapping these ATs is challenging because of atrial remodelling and its complex mechanisms, such as double ATs and multiple-loop ATs. High-density mapping can achieve precise identification of the circuits and critical isthmuses of ATs and improve the efficacy of catheter ablation. The purpose of this article is to review the mechanisms, mapping and ablation strategy, and outcome of ATs after AF ablation.

Epicardial bridge via the coronary sinus musculatures revealed by ultra-high-definition mapping

Mapping and ablation of perimitral flutter, a macro-reentrant tachycardia, can be sometimes challenging. We describe a case of perimitral atrial flutter following the pulmonary vein isolation in which mitral isthmus ablation failed to terminate the arrhythmia due to epicardial-endocardial breakthrough via the muscle fibers of coronary sinus. Ultra-high-definition mapping system was utilized to locate the epicardial bridge, and spot ablation of the lesion subsequently terminated the arrhythmia.

Downstream overdrive pacing and intracardiac concealed fusion to guide rapid identification of atrial tachycardia after atrial fibrillation ablation

Aims

Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping.

Methods and results

DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated.

Conclusion

Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT.

Patient-Specific Identification of Atrial Flutter Vulnerability-A Computational Approach to Reveal Latent Reentry Pathways

Atypical atrial flutter (AFlut) is a reentrant arrhythmia which patients frequently develop after ablation for atrial fibrillation (AF). Indeed, substrate modifications during AF ablation can increase the likelihood to develop AFlut and it is clinically not feasible to reliably and sensitively test if a patient is vulnerable to AFlut. Here, we present a novel method based on personalized computational models to identify pathways along which AFlut can be sustained in an individual patient. We build a personalized model of atrial excitation propagation considering the anatomy as well as the spatial distribution of anisotropic conduction velocity and repolarization characteristics based on a combination of a priori knowledge on the population level and information derived from measurements performed in the individual patient. The fast marching scheme is employed to compute activation times for stimuli from all parts of the atria. Potential flutter pathways are then identified by tracing loops from wave front collision sites and constricting them using a geometric snake approach under consideration of the heterogeneous wavelength condition. In this way, all pathways along which AFlut can be sustained are identified. Flutter pathways can be instantiated by using an eikonal-diffusion phase extrapolation approach and a dynamic multifront fast marching simulation. In these dynamic simulations, the initial pattern eventually turns into the one driven by the dominant pathway, which is the only pathway that can be observed clinically. We assessed the sensitivity of the flutter pathway maps with respect to conduction velocity and its anisotropy. Moreover, we demonstrate the application of tailored models considering disease-specific repolarization properties (healthy, AF-remodeled, potassium channel mutations) as well as applicabiltiy on a clinical dataset. Finally, we tested how AFlut vulnerability of these substrates is modulated by exemplary antiarrhythmic drugs (amiodarone, dronedarone). Our novel method allows to assess the vulnerability of an individual patient to develop AFlut based on the personal anatomical, electrophysiological, and pharmacological characteristics. In contrast to clinical electrophysiological studies, our computational approach provides the means to identify all possible AFlut pathways and not just the currently dominant one. This allows to consider all relevant AFlut pathways when tailoring clinical ablation therapy in order to reduce the development and recurrence of AFlut.

Mitral isthmus ablation using a circular mapping catheter positioned in the left atrial appendage as a reference for conduction block

Background

For perimitral atrial flutter (PMFL) developing after catheter ablation of atrial fibrillation (AF), to create a complete conduction block at the mitral isthmus (MI) is mandatory to terminate it, however, it is still challenging.

Methods

This study consisted of 80 patients (74 male, 61 ± 8.1 years) undergoing MI ablation. After a circular mapping catheter was positioned at the neck of the left atrial appendage (LAA), the MI ablation was performed on the MI line just below the LAA neck targeting the earliest activation recording site of the LAA catheter during pacing from the coronary sinus (CS). When ablation during CS pacing was not successful, an RF delivery during LAA pacing was applied targeting the earliest activation site just below the MI line. If the endocardial approach failed, an RF application inside the CS was attempted.

Results

With the endocardial approach, acute success was achieved in 51/80 patients (64%). Additional epicardial ablation from the CS was performed in 26/29 (90%) endocardially unsuccessful patients and conduction block at the MI was achieved in 21/26 (81%). Overall, complete conduction block at the MI was achieved in 72/80 patients (90%). At a mean follow-up of 16 ± 6 months, 20 patients (25%) had recurrence of atrial arrhythmias (AT: 12, AF: 8), and 10 (AT: 7, AF : 3) underwent a second procedure in which an LMI block line was completed in 3 (33%). PMFL was diagnosed in 6 out of 7 AT patients. No complications were observed.

Conclusions

Creating linear lesions just beneath the neck of the LAA was highly successful under the guidance of a circular mapping catheter in the LAA using a steerable sheath. An RF application from the CS was needed in less than half of the cases.

Characteristics of Residual Atrial Posterior Wall and Roof-Dependent Atrial Tachycardias after Pulmonary Vein Isolation

BACKGROUND

Roof-dependent atrial tachycardia (roof AT) sometimes occurs after pulmonary vein isolation (PVI) of atrial fibrillation (AF). This study aimed to investigate the relationship between the anatomy of the residual left atrial posterior wall and occurrence of roof AT.

METHODS

A total of 265 patients with AF who underwent PVI were enrolled. After the PVI, induced or recurrent roof AT was confirmed by an entrainment maneuver or activation mapping using a three-dimensional (3D) mapping system. To identify the predictors of roof AT, the minimum distance between both PVI lines (d-PVI) was measured by a 3D mapping system and the anatomical parameters, including the left atrial (LA) diameter, left atrial volume index (LAVi), and shape of the left atrial roof, were analyzed by 3D computed tomography.

RESULTS

Roof AT was documented in 11 (4.2%) of 265 patients. A multivariable analysis demonstrated that the d-PVI, Deep V shape of the LA roof, and LAVi were associated with roof AT occurrences (d-PVI: odds ratio: 0.72, confidence interval [CI]: 0.61-0.86, P < 0.001; Deep V shape: odds ratio: 0.19, CI: 0.04-0.82, P = 0.03; LAVi: odds ratio: 1.05, CI: 1.02-1.07, P = 0.001). A receiver-operating characteristic curve analysis yielded an optimal cut-off value of 15.5 mm and 55.7 mL/m² for the d-PVI and LAVi, respectively.

CONCLUSION

The shorter d-PVI at the LA roof, greater LAVi, and Deep V shape were associated with the occurrence of a roof AT.

Atrial Fibrillation Ablation Strategy: "Ready Made" or "Tailored"?

Atrial fibrillation (AF) is the most common arrhythmia leading to hospital admissions. Catheter ablation has evolved as an effective treatment strategy; however, ablation strategies continue to evolve due to the complex and multifactorial nature of atrial fibrillation. A standardized and primarily anatomical approach may not be sufficient to eliminate all mechanisms of atrial fibrillation. A tailored ablation strategy can target specific triggers and drivers of atrial fibrillation; however, it is limited by the accuracy and sensitivity of the methods used in identifying specific mechanisms of atrial fibrillation.

An atrial fibrosis-based approach for atrial fibrillation ablation

Since the emergence of atrial fibrillation (AF) ablation as a reliable method of restoring sinus rhythm, various approaches have been used to improve the efficacy while maximizing the safety of ablation. A major hurdle to optimizing outcomes for AF ablation has been the failure to recognize that the substrate of the individual patient plays a significant role in optimizing AF treatment. Using delayed-enhancement MRI for the detection of left atrial fibrosis, our group has been able to correlate these structural remodeling changes to outcomes of stroke, AF recurrence and congestive heart failure. This has provided us with information to optimize care of our AF patients based on screening for a fibrotic atrial cardiomyopathy, for which AF is the arrhythmic manifestation. By employing an MRI-guided approach for AF ablation, we have been able to optimize AF management and enhance the delivery of personalized medicine for our patients.

Catheter Ablation of Atrial Fibrillation Raises the Plasma Level of NGF-β Which Is Associated with Sympathetic Nerve Activity

PURPOSE

The expression of nerve growth factor-β (NGF-β) is related to cardiac nerve sprouting and sympathetic hyper innervation. We investigated the changes of plasma levels of NGF-β and the relationship to follow-up heart rate variability (HRV) after radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF).

MATERIALS AND METHODS

This study included 147 patients with AF (117 men, 55.8±11.5 years, 106 paroxysmal AF) who underwent RFCA. The plasma levels of NGF-β were quantified using double sandwich enzyme linked immunosorbent assay method before (NGF-βpre) and 1 hour after RFCA (NGF-βpost-1 hr). HRV at pre-procedure (HRVpre), 3 months (HRVpost-3 mo), and 1 year post-procedure (HRVpost-1 yr) were analyzed and compared with plasma levels of NGF-β.

RESULTS

1) The plasma levels of NGF-β significantly increased after RFCA (20.05±11.09 pg/mL vs. 29.60±19.43 pg/mL, p<0.001). The patients who did not show increased NGF-βpost-1 hr were older (p=0.023) and had greater left atrial volume index (p=0.028) than those with increased NGF-βpost-1 hr. 2) In patients with NGF-βpre>18 pg/mL, low frequency components (LF)/high-frequency components (HF) (p=0.003) and the number of atrial premature contractions (APCs, p=0.045) in HRVpost-3 mo were significantly higher than those with ≤18 pg/mL. 3) The LF/HF at HRVpost-3 mo was linearly associated with the NGF-βpre (B=4.240, 95% CI 1.114-7.336, p=0.008) and the NGF-βpost-1 hr (B=7.617, 95% CI 2.106-13.127, p=0.007). 4) Both NGF-βpre (OR=1.159, 95% CI 1.045-1.286, p=0.005) and NGF-βpost-1 hr (OR=1.098, 95% CI 1.030-1.170, p=0.004) were independent predictors for the increase of LF/HF at HRVpost-3 mo.

CONCLUSION

AF catheter ablation increases plasma level of NGF-β, and high plasma levels of NGF-βpre was associated with higher sympathetic nerve activity and higher frequency of APCs in HRVpost-3 mo.

Atrial tachycardias following atrial fibrillation ablation

One of the most important proarrhythmic complications after left atrial (LA) ablation is regular atrial tachycardia (AT) or flutter. Those tachycardias that occur after atrial fibrillation (AF) ablation can cause even more severe symptoms than those from the original arrhythmia prior to the index ablation procedure since they are often incessant and associated with rapid ventricular response. Depending on the method and extent of LA ablation and on the electrophysiological properties of underlying LA substrate, the reported incidence of late ATs is variable. To establish the exact mechanism of these tachycardias can be difficult and controversial but correlates with the ablation technique and in the vast majority of cases the mechanism is reentry related to gaps in prior ablation lines. When tachycardias occur, conservative therapy usually is not effective, radiofrequency ablation procedure is mostly successful, but can be challenging, and requires a complex approach.

Computer Vision Techniques for Transcatheter Intervention

Minimally invasive transcatheter technologies have demonstrated substantial promise for the diagnosis and the treatment of cardiovascular diseases. For example, transcatheter aortic valve implantation is an alternative to aortic valve replacement for the treatment of severe aortic stenosis, and transcatheter atrial fibrillation ablation is widely used for the treatment and the cure of atrial fibrillation. In addition, catheter-based intravascular ultrasound and optical coherence tomography imaging of coronary arteries provides important information about the coronary lumen, wall, and plaque characteristics. Qualitative and quantitative analysis of these cross-sectional image data will be beneficial to the evaluation and the treatment of coronary artery diseases such as atherosclerosis. In all the phases (preoperative, intraoperative, and postoperative) during the transcatheter intervention procedure, computer vision techniques (e.g., image segmentation and motion tracking) have been largely applied in the field to accomplish tasks like annulus measurement, valve selection, catheter placement control, and vessel centerline extraction. This provides beneficial guidance for the clinicians in surgical planning, disease diagnosis, and treatment assessment. In this paper, we present a systematical review on these state-of-the-art methods. We aim to give a comprehensive overview for researchers in the area of computer vision on the subject of transcatheter intervention. Research in medical computing is multi-disciplinary due to its nature, and hence, it is important to understand the application domain, clinical background, and imaging modality, so that methods and quantitative measurements derived from analyzing the imaging data are appropriate and meaningful. We thus provide an overview on the background information of the transcatheter intervention procedures, as well as a review of the computer vision techniques and methodologies applied in this area.

Contemporary Mapping Techniques of Complex Cardiac Arrhythmias - Identifying and Modifying the Arrhythmogenic Substrate

Cardiac electrophysiology has moved a long way forward during recent decades in the comprehension and treatment of complex cardiac arrhythmias. Contemporary electroanatomical mapping systems, along with state-of-the-art technology in the manufacture of electrophysiology catheters and cardiac imaging modalities, have significantly enriched our armamentarium, enabling the implementation of various mapping strategies and techniques in electrophysiology procedures. Beyond conventional mapping strategies, ablation of complex fractionated electrograms and rotor ablation in atrial fibrillation ablation procedures, the identification and modification of the underlying arrhythmogenic substrate has emerged as a strategy that leads to improved outcomes. Arrhythmogenic substrate modification also has a major role in ventricular tachycardia ablation procedures. Optimisation of contact between tissue and catheter and image integration are a further step forward to augment our precision and effectiveness. Hybridisation of existing technologies with a reasonable cost should be our goal over the next few years.

Detecting and monitoring arrhythmia recurrence following catheter ablation of atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia prompting clinical presentation, is associated with significant morbidity and mortality. The incidence and prevalence of this arrhythmia is expected to grow significantly in the coming decades. Of the available pharmacologic and non-pharmacologic treatment options, the fastest growing and most intensely studied is catheter-based ablation therapy for AF. Given the varying success rates for AF ablation, the increasingly complex factors that need to be taken into account when deciding to proceed with ablation, as well as varying definitions of procedural success, accurate detection of arrhythmia recurrence and its burden is of significance. Detecting and monitoring AF recurrence following catheter ablation is therefore an important consideration. Multiple studies have demonstrated the close relationship between the intensity of rhythm monitoring with wearable ambulatory cardiac monitors, or implantable cardiac rhythm monitors and the detection of arrhythmia recurrence. Other studies have employed algorithms dependent on intensive monitoring and arrhythmia detection in the decision tree on whether to proceed with repeat ablation or medical therapy. In this review, we discuss these considerations, types of monitoring devices, and implications for monitoring AF recurrence following catheter ablation.

Assessing the Relative Integrity of Formed Cardiac Linear Lesions by Recording Both Focal Monophasic Action Potentials and Contact Forces: A Technical Brief

The use of therapeutic ablation in patients with atrial fibrillation has become a mainstay in the treatment of this disease, yet often these individuals require multiple procedures. In other words, successful first time treatments are impacted by challenges, including the generation of linear lesions in certain anatomies like the mitral isthmus of the left atrium. Hence, there is a need to find ways to address the presence of unwanted conduction gaps at the time of lesion creation. In this paper, we describe a novel approach to examine conduction gaps, by using a proof of concept device to examine local electrical activation within the cardiac areas of an applied lesion, i.e., to locate gaps in the lesion set. To accomplish this, both epicardial and endocardial linear ablation lines composed of spot lesions with conduction gaps were created in a porcine model. The forces necessary to elicit monophasic action potentials (MAP) were collected from >200 measurements on the epicardium of the right ventricle. Ablations were then performed on the ventricular epicardium and left atrial mitral isthmus endocardially, while recording MAPs. We were able to successfully demonstrate the use of a proof of concept device to identify conduction gaps in linear lesion sets; furthermore, we were able to determine required contact forces to appropriately determine focal electrical changes of the underlying tissues. New catheter designs that incorporate capabilities to record focal MAPs could be employed clinically to better assess a given lesion quality and/or to determine the existence of an undesired conduction gap.

Electroanatomical mapping of atrial fibrillation: Review of the current techniques and advances

The number of atrial fibrillation (AF) catheter ablations performed annually has been increasing exponentially in the western countries in the last few years. This is clearly related to technological advancements, which have greatly contributed to the improvements in catheter ablation of AF. In particular, state-of-the-art electroanatomical mapping systems have greatly facilitated mapping processes and have enabled complex AF ablation strategies. In this review, we outline contemporary and upcoming electroanatomical key technologies focusing on new mapping tools and strategies in the context of AF catheter ablation.

Recurrent spontaneous clinical perimitral atrial tachycardia in the context of atrial fibrillation ablation

BACKGROUND

Recurrent perimitral atrial tachycardia (AT) is a challenging arrhythmia and is frequently encountered in the context of atrial fibrillation (AF) ablation.

OBJECTIVE

The purpose of this study was to investigate the clinical characteristics and the procedural and clinical outcomes in patients with recurrent perimitral atrial tachycardia (PMAT) after AF ablation.

METHODS

Among 520 consecutive ablation procedures for recurrent AT/AF after AF ablation, 40 procedures (patients) were performed for clinically recurrent PMAT 12.1 ± 13.6 months after the last procedure (total 2.2 ± 1.3 procedures). Previously, mitral isthmus (MI) linear ablation was performed in 26 of 40 procedures, including 13 procedures with complete block and 13 with 159.0 ± 23.0 ms of conduction delay without block. As a reference group, conduction delay was evaluated in 55 patients with incomplete MI block and absence of spontaneous PMAT during the follow-up period.

RESULTS

Recurrent PMATs were terminated by MI linear ablation in 26 of 40 patients. Bidirectional block across the MI and anterior line joining the mitral annulus and left atrial roof was achieved in 33 (82.5%) and 2 (5%) patients, respectively. At mean follow-up of 26.7 ± 14.5 months, 2 patients (5%) underwent reablation for spontaneously recurrent PMAT. At 12 months after the ablation procedure for PMAT, 73.5% of the patients were free from AT/AF. Conduction delay >149 ms predicted the occurrence of spontaneous PMAT with 80.0% sensitivity and 87.3% specificity.

CONCLUSION

PMAT can recur even after successful bidirectional MI linear block. Substantial conduction delay without block across the MI from a previous procedure(s) could predispose to recurrent PMAT. Although most clinical PMATs can be successfully treated by catheter ablation, very late recurrence is possible.