Posterior left atrial isolation is associated with a lower incidence of atrial tachycardia in patients with persistent atrial fibrillation

BACKGROUND

Patients may develop atrial tachycardia (AT) after left atrial (LA) ablation of persistent atrial fibrillation (AF).

METHODS

The population consisted of 101 consecutive patients (age = 64.3 ± 8.7 years, 70 males (69%), LA = 4.6 ± 0.8 cm, ejection fraction = 48.5 ± 16%) undergoing their initial procedure for persistent AF. After pulmonary vein isolation, patients either underwent posterior LA isolation (n = 50; study group) or linear ablation at the LA roof with verification of conduction block (n = 51; control group).

RESULTS

A repeat procedure was performed in 17 (34%) and 28 (55%) patients in the study and control groups, respectively (p = 0.02). Patients in the study group were less likely to develop AT (9/50 [18%] vs. 18/51 [35%]; p = 0.02), roof-dependent (1/50 [2%] vs. 8/51 [16%]; p = 0.008), and multi-loop AT (6/50 [12%] vs. 14/51 [27%]; p = 0.03) as compared to controls. Among various factors, only posterior LA isolation was associated with a lower likelihood of AT recurrence and roof tachycardia at redo procedure (OR, 0.37; 95% CI, 0.1 to 1.00, p = 0.05, and OR, 0.1, 95% CI, 0.01 to 0.96; p < 0.05, respectively).

CONCLUSIONS

In patients with persistent AF, posterior LA isolation is associated with a lower risk of a redo procedure, roof-dependent macro-reentry, and post-ablation AT in general as compared to controls who only received roof ablation. Posterior LA isolation also obviates the need for pacing maneuvers, and may be a more definitive endpoint than linear ablation at the LA roof.

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.

Atypical atrial flutter catheter ablation in the era of high-density mapping

BACKGROUND

Mapping and ablating atypical atrial flutters (AAFLs) have evolved greatly with advances in high-density 3D mapping systems over the last years.

METHODS

The objectives are to evaluate the feasibility of AAFL catheter ablation based on high-density mapping and minimizing entrainment and to better characterize AAFL circuits. Consecutive patients who underwent AAFL ablation using the EnSite Precision™ system and HD Grid™ mapping catheter (Abbott, Chicago, IL) between 06/2018 and 1/2022 were included. Mitral isthmus-dependent and roof-dependent AAFLs were classified as conventional circuits. All other AAFL circuits were classified as non-conventional circuits and were defined based on the location of the critical isthmus.

RESULTS

Sixty-two patients underwent AAFL ablation (mean age 68±11 years). A total of 95 AAFLs were mapped and 92 (97%) were successfully ablated. Fifty-three (85%) patients had a previous AF/AFL ablation. Forty-four (46%) AAFL circuits were classified as conventional and 51 (54%) as non-conventional. Conventional AAFL circuits had longer critical isthmuses (19.0±9.0 vs 10.8±6.3mm, p<0.001), a lower prevalence of slow conduction at the critical isthmus (59% vs 86%, p=0.005), and a longer radiofrequency time to AAFL termination (117±119 vs 51±66 s, p=0.002). Entrainment was attempted in 19 (20%) flutters and its use declined significantly over the study period. Procedural success rates remained high whether entrainment was used or not. Freedom of any atrial tachycardia was 65% over a follow-up of 13.8±9.0 months.

CONCLUSIONS

AAFL catheter ablation can be achieved with high procedural success rate using a contemporary strategy based on high-density mapping alone. Non-conventional circuits are frequent and present unique electrophysiological characteristics.

Magnetic resonance detection of advanced atrial cardiomyopathy increases the risk for atypical atrial flutter occurrence following atrial fibrillation ablation

AIMS

Recurrence of arrhythmia after catheter ablation of atrial fibrillation (AF) in the form of atypical atrial flutter (AFL) is common among a significant number of patients and often requires redo ablation with limited success rates. Identifying patients at high risk of AFL after AF ablation could aid in patient selection and personalized ablation approach. The study aims to assess the relationship between pre-existing atrial cardiomyopathy and the occurrence of AFL following AF ablation.

METHODS AND RESULTS

We analysed a cohort of 1007 consecutive AF patients who underwent catheter ablation and were included in a prospective registry. Patients who did not have baseline cardiac magnetic resonance imaging and late gadolinium enhancement (LGE-CMR) or did not experience any recurrences were excluded. A total of 166 patients were included gathering 56 patients who underwent re-ablation due to AFL recurrences and 110 patients who underwent re-ablation due to AF recurrences (P = 0.11). A multiparametric assessment of atrial cardiomyopathy was based on basal LGE-CMR, including left atrial (LA) volume, LA sphericity, and global and segmental LA fibrosis using semiautomated post-processing software. Out of the initial cohort of 1007 patients, AFL and AF occurred in 56 and 110 patients, respectively. An age higher than 65 [odds ratio (OR) = 5.6, 95% confidence interval (CI): 2.2-14.4], the number of previous ablations (OR = 3.0, 95% CI: 1.2-7.8), and the management of ablation lines in the index procedure (OR = 2.5, 95% CI: 1.0-6.3) were independently associated with AFL occurrence. Furthermore, several characteristics assessed by LGE-CMR were identified as independent predictors of AFL recurrence after the index ablation for AF, such as enhanced LA sphericity (OR = 1.3, 95% CI: 1.1-1.6), LA global fibrosis (OR = 1.03, 95% CI: 1.01-1.07), and increased fibrosis in the lateral wall (OR = 1.03, 95% CI: 1.01-1.04).

CONCLUSION

Advanced atrial cardiomyopathy assessed by LGE-CMR, such as increased LA sphericity, global LA fibrosis, and fibrosis in the lateral wall, is independently associated with arrhythmia recurrence in the form of AFL following AF ablation.

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.

The History of Atrial Flutter Electrophysiology, from Entrainment to Ablation: A 100-Year Experience in the Precision Electrocardiology

Atrial flutter (AFL) is a regular supraventricular reentrant tachycardia generating a continuous fluttering of the baseline electrocardiography (ECG) at a rate of 250 to 300 beats per minute. AFL is classified based on the involvement of the cavo-tricuspid isthmus in the circuit. The "isthmic" (or type 1) AFL develops entirely in the right atrium; this circuit is commonly activated in a counter-clockwise direction, generating the common sawtooth ECG morphology in the inferior leads (slow descendent-fast ascendent). AFL can be nonisthmus dependent (type 2), often presenting with faster atrial rate and most commonly a left atrial location.

Electrocardiographic Approach to Atrial Flutter: Classifications and Differential Diagnosis

Atrial flutter (AFL) is a macro-reentrant arrhythmia characterized, in a 12 lead ECG, by the continuous oscillation of the isoelectric line in at least one lead. In the typical form of AFL, the oscillation is most obvious in the inferior leads, due to a macro-reentrant circuit localized in the right atrium, with the cavo-tricuspid isthmus as a critical zone.: This circuit can be activated in a counterclockwise or clockwise direction generating in II, III, and aVF leads, respectively, a slow descending/fast ascending F wave pattern (common form of typical AFL) or a balanced ascending/descending waveform (uncommon form of typical AFL). Atypical AFLs (scar-related) do not include the CTI in the circuit and show an extremely variable circuit location and ECG morphology.

Pathophysiology of Atypical Atrial Flutters

Atypical atrial flutters are complex supraventricular arrhythmias that share different pathophysiological aspects in common. In most cases, the arrhythmogenic substrate is essentially embodied by slow-conducting areas eliciting re-entrant circuits. Although atrial scarring seems to promote slow conduction, these arrhythmias may occur even in the absence of structural heart disease. To set out the ablation strategy in this setting, three-dimensional mapping systems have proved invaluable over the last decades, helping the cardiac electrophysiologist understand the electrophysiological complexity of these circuits and easily identify critical areas amenable to effective catheter ablation.

Atypical Cases of Typical Atrial Flutter? A Case Study

Ablation of typical atrial flutter has a high safety and efficacy profile, but hidden pitfalls may be encountered. In some cases, a longer cycle length with isoelectric lines is associated with a different or more complex arrhythmogenic substrate, which may be missed if conduction block of the cavotricuspid isthmus is performed in the absence of the clinical arrhythmia. Prior surgery may have consistently modified the atrial substrate and complex or multiple arrhythmias associated with an isthmus-dependent circuit can be encountered. In these cases, electroanatomic mapping is useful to guide the procedure and plan an appropriate ablation strategy.

Mapping and Ablation of Atypical Atrial Flutters

Atypical atrial flutters are complex, hard-to-manage atrial arrhythmias. Catheter ablation has progressively emerged as a successful treatment option with a remarkable role played by irrigated-tip catheters and 3D electroanatomic mapping systems. However, despite the improvement of these technologies, the ablation results may be still suboptimal due to the progressive atrial substrate modification occurring in diseased hearts. Hence, a patient-tailored approach is required to improve the long-term success rate in this scenario, aiming at achieving specific procedure end points and detecting any potential arrhythmogenic substrate in each patient.

Pacemaker lead-related macroreentrant atrial tachycardia

Macroreentrant atrial circuits are frequently associated with scarring. Previous reports have shown the possible development of scar tissue that is adjacent to pacemaker (PM) leads. However, reports of PM lead-related reentrant tachycardia are scarce. We report the case of a 63-year-old woman who presented with macroreentrant atrial tachycardia (MAT), related to the atrial trajectory of an old single-lead ventricular PM, that was successfully treated with radiofrequency ablation after an conventional electrophysiological study ruled out isthmus-dependent atrial flutter and provided sufficient data to confirm this diagnosis.This report presents a case of MAT originating around the trajectory of a PM lead, probably because of scar tissue that developed adjacent to the lead. Experimental studies have already shown that interstitial atrial fibrosis may develop adjacent to a ventricular single-lead. This finding suggests that MAT develops in patients with this specific condition. Recognizing this condition is important for managing these arrhythmias and performing safe ablation with the preservation of PM lead integrity.

High-density mapping with fragmentation analysis in patients with reentrant atrial tachycardias (MAP-FLURHY study)

PURPOSE

Reentrant atrial tachycardias (ATs) use areas of slow conduction that can be visualized as fragmented electrograms. We aimed to test an ablation strategy based on the identification and ablation of spots with fragmented electrograms in reentrant ATs, using Rhythmia navigation system.

METHODS

All consecutive patients from June 2016 to June 2019 were included. The IntellaMap ORION Catheter was used to detect sites with fragmentation, arbitrarily defined as fragmented electrograms > 70 ms. Entrainment was used to check if these areas belonged to the AT circuit. Ablation targeted the longest fragmented electrogram within the circuit: focal ablation for microreentries and lines for macroreentries. Ablation success was defined from each AT as conversion to sinus rhythm or another AT.

RESULTS

Twenty-seven consecutive patients with 44 mappable ATs were included. All ATs showed sites with fragmented electrograms (104 sites; 2.4 sites per AT); 43/44 ATs had fragmented electrograms within the circuit, which were the target of ablation. Ablation success: 34/36 ATs (94%); success could not be assessed in 8 circuits, in 6 due to mechanical conversion to sinus rhythm at the target fragmented site. Fragmented electrograms within the AT circuits were longer than electrograms outside the circuits (110 ± 30 vs 90 ± 15 ms, p < 0.001). A fragmentation duration > 100 ms/ > 40% of the AT cycle length predicted to be a successful site for ablation with 72.3%/73.8% specificity, respectively. Sixty-two percent of the patients were free from atrial arrhythmias at 1 year.

CONCLUSIONS

Most ATs had detectable fragmented electrograms within the circuit, which could be the target of ablation with high efficacy.

High-density versus low-density mapping in ablation of atypical atrial flutter

PURPOSE

Ablation of atypical atrial flutter (AAFL) can be challenging. High-density (HD) mapping of ablation targets may potentially increase procedural success and freedom from recurrent AAFL. The objective of the present study was to explore whether employing HD mapping leads to a more favorable outcome in ablation of AAFL.

METHODS

We compared baseline and procedural characteristics, procedural success, safety and outcome of mapping and ablation of atypical flutter in three groups. (1) HD Grid catheter + the high-density electroanatomical mapping (EAM) system EnSite Precision; (2) standard 10-pole circular mapping catheter (CMC) + EnSite Precision; (3) CMC + the low-density EnSite Velocity EAM. Voltage and propagation maps were constructed.

RESULTS

Mapping of 142 AAFL in 82 patients was performed. Acute ablation success was 78%, 68%, and 51% in groups 1, 2, and 3 (p = 0.037 between group 1 and 3, non-significant between groups otherwise). Moreover, 8%, 27%, and 36% of flutters were unmappable in groups 1, 2, and 3, respectively (p < 0.05 between group 1 and both groups 2 and 3). AAFL recurrence at 1-year FU was 26%, 36%, and 62% in groups 1, 2, and 3 (p = 0.007 between groups 1 and 3, p = 0.05 between groups 2 and 3). AAFL-free survival was significantly higher in patients mapped with Precision than with Velocity (p = 0.011). No strokes or mortality occurred within 30 days.

CONCLUSIONS

Acute procedural success of ablation of atypical atrial flutter is higher and the number of unmappable flutters is lower using the HD Grid mapping catheter in combination with the high-density EnSite Precision system, as compared to a decapolar circular mapping catheter and the low-density EnSite Velocity EAM system. This may lead to increased freedom from recurrent AAFL at 1 year. HD mapping is safe.

Catheter ablation of complex atrial tachyarrhythmias in adult patients with cor triatriatum

PURPOSE

Reports concerning clinical characteristics of cor triatriatum and approaches for catheter ablation of complex atrial tachyarrhythmias remain limited. Here, we describe successful catheter ablation treatments for complex atrial tachyarrhythmias in patients with cor triatriatum and address the clinical caveats.

METHODS

Demographic characteristics, electrophysiologic findings, and ablation results in four patients with cor triatriatum were described.

RESULTS

Catheter ablation was performed in four patients with cor triatriatum (three sinister and one dexter) and complex atrial arrhythmias (three with persistent atrial fibrillation (AF) and one with atypical left atrial flutter). A transseptal puncture was selectively directed into the accessory compartment containing the pulmonary veins. A comprehensive preview involving transthoracic echocardiography, transesophageal echocardiography, and computed tomography of the pulmonary veins was critical for proper positioning of ablation catheters. The pulmonary veins remain the major triggers or initiators for AF, and four pulmonary vein isolation procedures were sufficient to achieve successful results with negative inducibility test in the patients with AF. Heterogeneous conduction and complex fractionated signals were observed on the fibromuscular membrane. Atypical flutter was terminated during ablation over the connection between membrane and left atrial roof. The procedure was successfully performed on all patients without complications. No acute recurrences of atrial tachyarrhythmias were observed in any of the patients during short-term follow-up.

CONCLUSIONS

Catheter ablation is a feasible and efficient therapeutic strategy for treating complex atrial tachyarrhythmias in patients with cor triatriatum. Atrial remodeling due to anatomical obstruction or heterogeneous conduction of the fibromuscular membrane may serve as an arrhythmic substrate.

A new electrophysiologic triad for identification and localization of the critical isthmus in atrial flutter

INTRODUCTION

Atypical atrial flutter (AFL) is a supraventricular arrhythmia that can be treated with catheter ablation. However, this strategy yields suboptimal results and the best approach is yet to be defined. Carto® electroanatomical mapping (EAM) version 7 displays a histogram of the local activation times (LAT) of the tachycardia cycle length (TCL), in addition to activation and voltage maps. Using these EAM tools, the study aimed to assess the ability of an electrophysiologic triad to identify and localize the critical isthmus in AFL.

METHODS

Retrospective analysis using Carto® EAM of a single center registry of individuals who underwent left AFL ablation over one year. Subjects with non-left AFL, no high-density EAM, under 2000 points or no left atrium wall or structure mapping were excluded. Sites where arrhythmia is terminated via ablation were compared to an electrophysiologic triad comprising areas of low-voltage (0.05 to 0.3 mV), deep histogram valleys (LAT-valleys) with less than 20% density points relative to the highest density zone and a prolonged LAT-valley duration, which included 10% or more of the TCL. The longest LAT-valley was designated as the primary valley, while additional valleys were named as secondary.

RESULTS

A total of nine subjects (six men, median age 75, interquartile range 71-76 years) were included. All patients presented with left AFL and 66% had a history of ablation for atrial fibrillation and/or flutter. The median TCL and collected points were 254 ms (220-290) and 3300 (IQR 2410-3926) points, respectively. All individuals with AFL presented with at least one LAT-valley on the analyzed histograms, which corresponded to heterogeneous low voltage areas (0.05 to 0.3 mV) and affected more than 10% of TCL. Six of the nine patients presented with a secondary LAT-valley. All arrhythmias were terminated successfully following radiofrequency ablation at the primary LAT-valley location. After a minimum three-month follow-up all patients remained in sinus rhythm.

CONCLUSION

An electrophysiologic triad identified the critical isthmus in AFL for all patients. Further studies are needed to assess the usefulness of this algorithm in improving catheter ablation outcomes.

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

PURPOSE

This study aims to describe a novel method of High Density Activation Sequence Mapping combined with Voltage Gradient Mapping Overlay (HD-VGM) to quickly localize and terminate atypical atrial flutter.

METHODS

Twenty-one patients presenting with 26 different atypical atrial flutter circuits after a previous catheter or surgical AF ablation were studied. HD-VGM was performed with a commercially available impedance-based mapping system to locate and successfully ablate the critical isthmus of each tachycardia circuit. The results were compared to 21 consecutive historical control patients who had undergone an atypical flutter ablation without HD-VGM.

RESULTS

Twenty-six different atypical flutter circuits were evaluated. An average 3D anatomic mapping time of 12.39 ± 4.71 min was needed to collect 2996 ± 690 total points and 1016 ± 172 used mapping points. A mean of 195 ± 75 s of radiofrequency (RF) energy was needed to terminate the arrhythmias. The mean procedure time was 135 ± 46 min. With a mean follow-up 16 ± 9 months, 90% are in normal rhythm. In comparison to the control cohort, the study cohort had a shorter procedure time (135 ± 46 vs. 210 ± 41 min, p = 0.0009), fluoroscopy time (8.5 ± 3.7 vs. 17.7 ± 7.7 min, p = 0.0021), and success in termination of the arrhythmia during the procedure (100 vs. 68.2%, p = 0.0230).

CONCLUSIONS

Ablation of atypical atrial flutter is challenging and time consuming. This case series shows that HD-VGM mapping can quickly localize and terminate an atypical flutter circuit.

Ablation of atypical atrial flutters using ultra high density-activation sequence mapping

PURPOSE

The purpose of this study was to evaluate ultra high density-activation sequence mapping (UHD-ASM) for ablating atypical atrial flutters.

METHODS

For 23 patients with 31 atypical atrial flutters (AAF), we created UHD-ASM.

RESULTS

Demographics age = 65.3 ± 8.5 years, male = 78%, left atrial size = 4.66 ± 0.64 cm, redo ablation 20/23(87%). AAF were left atrial in 30 (97%). For each AAF, 1273 ± 697 points were used for UHD-ASM. Time to create and interpret the UHD-ASM was 20 ± 11 min. For every AAF, the entire circuit was identified. Thirty (97%) were macroreentry. AAF cycle length was 267 ± 49 ms, and the circuit length was 138 ± 38 mm (range 35-187). Macroreentry atrial flutters took varied pathways, but each had an area of slow conduction (ASC) averaging 16 ± 6 mm (range 6-29) in length. Entrainment was not utilized. We targeted the ASC and ablation terminated AAF directly in 19/31 (61.3%) and altered AAF activation in 7/31 (22.6%), all of which terminated directly with additional mapping/ablation. AAF degenerated to atrial fibrillation in 2/31 (6.5%) with RF and could not be reinduced after ASC ablation. Median time from initial ablation to AAF termination was 64 s. Thus, 28/31 (90.3%) terminated with RF energy and/or could not be reinduced after ASC ablation. At 1 year of follow-up, 77% were free of atrial tachycardia or atrial flutter and 61% were free of all atrial arrhythmias.

CONCLUSIONS

Using rapidly acquired UHD-ASM, the entire AAF circuit as well as the target ASC could be identified. Most AAF were left atrial macroreentry. Ablation of the ASC or microreentry focuses directly terminated or eliminated AAF in 90.3% without the need for entrainment mapping.

Late atypical atrial flutter after ablation of atrial fibrillation

Cardiac surgery for structural heart disease (often involving the left atrium) and radiofrequency catheter ablation of atrial fibrillation have led to an increased incidence of regular atrial tachycardias, often presenting as atypical flutters. This type of flutter is particularly common after pulmonary vein isolation, especially after extensive atrial ablation including linear lesions and/or defragmentation. The authors describe the case of a 51-year-old man, with no relevant medical history, referred for a cardiology consultation in 2009 for paroxysmal atrial fibrillation. After failure of antiarrhythmic therapy, he underwent catheter ablation, with criteria of acute success. Three years later he again suffered palpitations and atypical atrial flutter was documented. The electrophysiology study confirmed the diagnosis of atypical left flutter and reappearance of electrical activity in the right inferior pulmonary vein. This vein was again ablated successfully and there has been no arrhythmia recurrence to date. In an era of frequent catheter ablation it is essential to understand the mechanism of this arrhythmia and to recognize such atypical flutters.