Catheter ablation of atypical atrial flutter: a novel 3D anatomic mapping approach to quickly localize and terminate atypical atrial flutter

Peak frequency mapping of atypical atrial flutter

INTRODUCTION

Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters.

METHODS AND RESULTS

LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD-Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low-voltage as 0.1-0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t-testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low-voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001).

CONCLUSION

Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical atrial flutter.

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 .

Clinical impact of high-density mapping on the acute and long term outcome of atypical atrial flutter ablations

PURPOSE

We evaluated the clinical impact of the high-density (HD) mapping compared with the standard low-density (LD) ablation catheter mapping technique in the treatment of AFLs.

METHODS

We retrospectively evaluated short and long outcomes of patients approached with an HD and a LD electro-anatomical strategy for atypical AFLs.

RESULTS

Eighty-seven patients were included. Patients were almost male (60%), relatively old (65 ± 8 years), with a moderate CHA2DS2Vasc score (2.3 ± 1.3), a preserved ejection fraction (58 ± 6), and moderate atrial dilatation (44 ± 7 mm). Baseline clinical characteristics were comparable between groups (p = NS). Among AFLs, 10 (11%) were located in the right and 78 (89%) in the left atrium, including 22 (28%) roof dependent and 37 (47%) mitral dependent (p = NS). Sinus rhythm restoration during ablation was more frequently observed in the HD group (79% vs 56%, p = 0.037), without differences in mapping time, procedural time, and radiological dose (p = NS). Overall AFL/AT/AF recurrence rate at 1, 2, and 3 years was lower in the HD group (14% vs 37% p = 0.02, 14% vs 48% p = 0.002 and 14% vs 50% p < 0.001, respectively) with a time-dependent trend only in the LD group (37% vs 48% vs 50% at 1, 2, and 3 years respectively, p = 0.059). HD mapping (OR 0.17; 95% CI 0.04-0.66) and younger age (OR 1.09; 95% CI 1.01-1.19) resulted independent predictors of overall arrhythmias at follow-up.

CONCLUSIONS

Short- and long-term outcomes of atypical AFL ablation were better in the case of HD mapping, which resulted independent predictor of arrhythmia recurrences.

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.

Substrate-based ablation of atypical atrial flutter in patients with atrial cardiomyopathy

Background

Standard therapy of atypical atrial flutter (AFL) aims at deploying ablation lines between two non-conducting anatomical structures, thereby creating a line of block within the re-entry circuit. We have developed an ablation strategy, where we incorporate voltage information as a surrogate for atrial fibrosis from the electro-anatomical map (EAM) during AFL ablation procedures to create individualized, substrate-based ablation lines along the area of most pronounced low-voltage within the reentry-circuit.

Objective

The aim of this study was to evaluate acute procedural success and long-term outcome of a substrate-based ablation (SBA) strategy in comparison to a standard anatomically based ablation (ABA) strategy for the ablation of atypical AFL.

Methods

Patients that underwent ablation for AFL at our institution were included. SBA procedures were compared to ABA procedures. Endpoints were acute termination of AFL and recurrence of the index AFL or any other AFL during follow-up.

Results

We included 47 patients, 24 individuals (51.1%) in the SBA group and 23 patients (48.9%) in the ABA group. Most patients had signs of atrial cardiomyopathy, namely enlarged left atrial diameter (LAD) and extended amount of left atrial low-voltage areas (LVA). Termination of AFL occurred in 27 of 29 (93.1%) AFL in the SBA group and in 28 of 31 (90.3%) AFL in the ABA group (p = 0.99). Freedom from recurrence of any atypical AFL after 2.5 years was 21.5% in the ABA group compared to 48.8% in the SBA group (p = 0.047).

Conclusion

Substrate-based ablation is as effective as an anatomically-based ablation in the acute termination of AFL but yields better rhythm outcome with less recurrence of AFL in patients with atrial cardiomyopathy.

Ablation of Left Atrial Tachycardia following Catheter Ablation of Atrial Fibrillation: 12-Month Success Rates

The treatment of atrial tachycardia following catheter ablation of atrial fibrillation is often challenging. Electrophysiological studies using high-resolution 3D mapping systems have contributed significantly to their understanding, and new ablation approaches have shown high rates of acute terminations with low recurrences for the clinical AT. However, patient populations are very heterogeneous, and long-term data of the freedom from any atrial tachycardia or any arrhythmia are still sparse. To evaluate long-term success, a unified patient population and predefined ablation strategies are preferred. In this study, we present 12-month success and mean 30 month follow-up data of catheter ablation of left atrial tachycardia. All 35 patients had a history of pulmonary vein isolation (PVI), 71% of which had a previous substrate modification. A total of 54 ATs, with a mean cycle length 297 ± 86 ms, 31 macro-reentries, and 4 localized reentries, were targeted. The ablation strategy to be used was given by the study protocol, depending on the type of reentry and the number of critical isthmuses. All available ablation strategies were included: standard (anatomical) lines, individual lines, critical isthmuses, and focal ablation. All ATs were terminated by ablation. A total of 91% terminated upon the first ablation strategy. Freedom from any AT after 12 months was 82%, and from any arrhythmia, it was 77%. The multi-procedure success after 30 months was 65% for any AT and 55% for any arrhythmia. In conclusion, individual ablation strategies based on the reentry mechanism and the number of critical isthmuses seems promising and demonstrates a high long-term clinical success. Tachycardia comprising a single critical isthmus can be ablated by critical isthmus ablation only. These patients present with the highest 12-month and long-term success rates.

Comparison of the Anterior Septal Line and Mitral Isthmus Line for Perimitral Atrial Flutter Ablation Using Robotic Magnetic Navigation

Background

Perimitral atrial flutter (PMAFL) is one of the most common macro-reentrant left atrial tachycardias. Mitral isthmus (MI) linear ablation is a common strategy for the treatment of PMAFLs, and anterior septum (AS) linear ablation has emerged as a novel ablation approach. We aimed at assessing the effectiveness of AS linear ablation using robotic magnetic navigation for PMAFL ablation.

Methods

In this retrospective study, a total of 36 consecutive patients presented with AFL as the unique arrhythmia or accompanied with atrial fibrillation (AF) who underwent catheter ablation were enrolled. Patients were classified into two groups according to the different ablation strategies, the MI line group (10 patients) and the AS line group (26 patients).

Results

The clinical baseline characteristics of patients in the two groups were nearly identical. There were no significant differences in procedure time (148.7 ± 46.1 vs. 123.2 ± 30.1 min, P=0.058) or radiofrequency ablation time (25.9 ± 11.4 vs. 23.5 ± 12.6 min) between the two groups. Fluoroscopy time was longer in the MI line group (8.0 ± 4.4 vs. 5.1 ± 2.7 min, P=0.024), and the acute success rate was higher in the AS line group versus the MI line group (96.2% vs. 70%, P=0.025). The long-term freedom from arrhythmia survival rate was higher in the AS line group (73%) than in the MI line group (40%) after a mean follow-up time of 37.4 months with a 3-month blanking period (P=0.049).

Conclusions

AS linear ablation is an effective and safe strategy for PMAFL ablation using robotic magnetic navigation.

Influence of common zones of low-amplitude activity on the mechanism and treatment of atrial arrhythmias

Background: The treatment of left atrial flutter is a problem that requires a deep understanding of the underlying complex mechanism of arrhythmia. Although a considerable experience exists already in understanding the mechanisms underlying atrial flutter after ablation or surgery, little is known about atypical forms of atrial flutter in patients who have not previously undergone ablation or other cardiac surgery. Clinical case description: We present a clinical case of interventional treatment of a patient with atypical atrial flutter who had not previously undergone surgical or interventional heart surgery. This clinical observation demonstrates the role of common zones of low-amplitude activity on the mechanism and treatment of atrial arrhythmias. Widespread areas of low-amplitude activity in the left atrium can create barriers to the propagation of excitation, which can cause atypical atrial flutter. Conclusion: When performing a surgical intervention, high-density mapping will help to visualize the mechanism of this arrhythmia. Understanding the mechanism of atypical atrial flutter will help to minimize the RF exposure during the treatment.

Incidence, electrophysiological characteristics, and long-term follow-up of perimitral atrial flutter in patients with previously confirmed mitral isthmus block

INTRODUCTION

After mitral isthmus (ΜΙ) catheter ablation, perimitral atrial flutter (PMF) circuits can be maintained due to the preservation of residual myocardial connections, even if conventional pacing criteria for complete MI block are apparently met (MI pseudo-block). We aimed to study the incidence, the electrophysiological characteristics, and the long-term outcome of these patients.

METHODS

Seventy-two consecutive patients (mean age 62.4 ± 10.2, 62.5% male) underwent MI ablation, either as part of an atrial fibrillation (AF) ablation strategy (n = 35), or to treat clinical reentrant atrial tachycardia (AT) (n = 32), or to treat AT that occurred during ablation for AF (n = 5). Ιn all patients, the electrophysiological characteristics of PMF circuits were studied by high-density mapping.

RESULTS

Mitral isthmus block was successfully achieved in 69/72 patients (95.6%). Five patients developed PMF after confirming MI block. In these patients, high-density mapping during the PMF showed a breakthrough in MI with extremely low impulse conduction velocity (CV). In contrast, in usual PMF circuits that occurred after AF ablation, the lowest CV of the reentrant circuit was of significantly higher value (0.07 ± 0.02 m/s vs 0.25 ± 0.07 m/s, respectively; P < .001). Patients presented with clinical AT had better prognosis in maintaining sinus rhythm after MI ablation compared with patients presented with AF.

CONCLUSION

Perimitral atrial flutter with MI pseudo-block may be present after MI ablation and has specific electrophysiological features characterized by remarkably slow CV in the MI. Thus, even after MI block is achieved, a more detailed mapping in the boundaries of the ablation line or reinduction attempts may be needed to exclude residual conduction.

The evolution of mapping and ablation techniques in the treatment of atrial tachycardias occurring after atrial fibrillation ablation

PURPOSE

A possible consequence of atrial fibrillation (AF) ablation is the occurrence of organized atrial tachycardias (ATs). ATs after AF ablation (ATAAF) may be more symptomatic than AF itself, thus necessitating catheter ablation. We evaluated the prognostic significance of clinical and invasive characteristics for long-term sinus rhythm (SR) maintenance following ATAAF ablation and assessed the effect of technological developments on these results.

METHODS AND RESULTS

Fifty-six consecutive patients with symptomatic ATAAF participated in the study and 114 ATAAF were revealed (2.04 ± 0.93 per patient). Sixty-eight ATAAF (60%) were macroreentrant and 33 (29%) were microreentrant circuits, while 13 (11%) were focal automatic tachycardias. The mean follow-up was 40 ± 18 months with 34 (61%) patients maintaining SR. Treatment with contact force (CF) catheters and EnSite AutoMap module (n = 11) showed significantly better AT/AF free rates at 1-year follow-up (10/11, 91%) compared with treatment using CF catheters but not AutoMap module (n = 13) (8/13, 62%) and treatment with use of neither of these modalities (n = 32) (16/32, 50%). Among patients with macroreentrant circuits around the mitral annulus or left atrial roof (n = 38), the group treated with complete linear lesions in anatomical isthmuses (n = 25) showed significantly better SR maintenance (19/25, 76%) compared with patients (n = 13) treated by empirical ablation in critical functional areas (6/13, 46%).

CONCLUSIONS

Technology advancement contributes substantially to long-term success in SR maintenance, by achieving detailed mapping and more effective ablation of ATAAF. The targeting of macroreentrant circuits by creating anatomical linear lesions appears to provide better results.