Perimitral Atrial Tachycardia Research Articles

Pulsed field ablation for complex resistant atrial tachycardia recurring after radiofrequency ablation of persistent atrial fibrillation

Abstract Background There is a limited knowledge on immediate and long-term efficacy of pulsed field ablation (PFA) for residual atrial tachycardia (AT) recurring after persistent atrial fibrillation ablation (AF). Purpose To present immediate and medium-term outcome of PFA (Farapulse) for complex AT recurring after ≥1 radiofrequency ablation (RFA) of primary (longstanding) persistent AF. Methods In 5/2022-10/2023, 81 patients (64±8 years, 19 females) underwent PFA for complex AT in 83 PFA procedures after prior RFA procedure(s); in first (n=21), second (n=33), third (n=23), fourth (n=5), or fifth (n=1) repeat ablation procedure, respectively. Mapping/ablation strategy was directed by the CS activation/entrainment to: 1) no 3D mapping and direct PFA in left atrium (n=67); 2) PFA directly after 3D LA mapping (n=9); 3) PFA following RFA after 3D LA mapping (n=7). AT sources were classified as macroreentry (MRAT) (perimitral, roof-dependent, typical flutter) or localized (LOCAT) in case of smaller reentry or ectopic origin. Results At the procedure onset, persistent AT was present in 58 patients, in the remaining cases AT (n=21) or AF (n=4) were induced. AF eventually occurred at some time of procedure in another 10 patients and was terminated by ablation at LA ridge/CS/LOM region 8x, LA posterior wall 3x, LUPV 1x, RUPV 1x, and RA low lateral wall 1x. Only MRAT, only LOCAT, or both AT types were found at 34 (41%), 35 (42%), and 14 (17%) procedures, respectively. A total of 125 ATs was identified (1, 2, and 3 ATs in 52, 20, and 11 patients). MRAT (n=60) included 32 perimitral ATs, 20 roof-dependent ATs, and 8 typical flutters. LOCAT (n=65) included RUPV source (n=1), LA extraPV sources (n=59), and RA sources (n=5). SR was restored with a 5±7 PFA applications at the site of AF source, total of PFA deliveries was 71±27, and procedure and fluoroscopy times were and 89±37 and 9±5 minutes, respectively. In the 7 patients with initial ineffective 6, 6, 11, 5, 18, 10, and 2 minutes of RFA, the AT was converted into SR by subsequent 1, 4, 1, 13, 4, 24, and 20 PFA applications. All ATs were terminated and noninducibility was achieved in 82 (99%) and 74 (89%) procedures, respectively. In 52 patients with >3 month follow-up, 46 (88%) patients remain in stable SR (41 / 79%) off AAD); 3 and 3 patients have paroxysmal or persistent AT. Conclusion PFA with catheter Farapulse can affect complex/epicardial AT sources resistant to RFA in prior or present ablation procedure; however, there is a certain discrepancy between high efficacy in AT terminating and medium-term clinical outcome.

Electrophysiological characteristics and durability of index pulsed field ablation lesions from redo procedures for atrial arrhythmia recurrences

Abstract Background Catheter ablation for atrial fibrillation (AF) has been performed using mainly thermal energy sources (radiofrequency, cryo, or laser). Pulsed field ablation (PFA) is a novel energy with interesting safety and effectiveness demonstrated in previous preclinical and clinical trials. Purpose We sought to assess the electrophysiological characteristics and durability of PFA index procedure procedures using a pentaspline PFA catheter as assessed based on redo procedures in patients with AT/AF recurrences. Methods A total of 169 patients (paroxysmal AF (PAF), 120; persistent AF (PsAF), 49) who underwent PFA using a pentaspline PFA catheter in the index procedure from November 2021 to July 2023 were studied. Pulmonary vein isolation (PVI) was performed with PFA in all patients with additional PFA lines: i)posterolateral mitral isthmus (MI) ablation in 25, ii) posterior line in 40 patients. Twenty-seven patients (PAF, 11; PsAF, 16) had atrial arrhythmia (atrial tachycardia (AT) or AF) recurrence after a 3-month blanking period (16%). We analyzed the electrophysiological characteristics of previous PFA lesions in 18 (PAF, 8; PsAF, 10) out of 27 patients in whom an activation and voltage mapping using 3-D electroanatomical mapping system was available. Results PV reconnections were identified in 7 of 18 patients (13PVs/69PVs ,18.8%) at the PV-LA junctions and carina regions of both left PVs and right PVs, mainly at the anterior aspect of right PV carina (n=6). In 6 out of 10 redo cases, posterolateral MI line using PFA was performed in the index procedure based on our strategy for PsAF ablation. In these 6 cases with previous MI line using PFA for PsAF ablation endocardial PFA was combined with marshall vein ethanolization(Et-VOM). Additional RF endocardial ablation and in the CS was needed to achieve MI block in 2 (33%) in the index procedure. 3D mapping of redo cases showed MI line gaps in 6/6 (100%). In 3 of those patients, the clinical arrhythmia recurrence was a perimitral AT (50%). Nine of the 10 PsAF patients who underwent a redo procedure had an index procedure complete posterior line. Remapping demonstrated durable block in 7/9 (78%). One of these patients presented with a roof dependent AT diagnosed in the redo procedure. Durable posterior lines received a significantly larger number of PFA deliveries during the index procedure: 16.4±3.3 vs 10.0±2.8 respectively, p=0.041). Conclusion This study based on redo cases after PFA using a pentaspline PFA catheter shows that PFA is associated with high durability for PVI and posterior line ablation. However the durability of MI line are poor, even when combined with VOM ethanolization. Further research is needed to define the optimal number of deliveries required to achieve durable posterior line block.

Strategy to achieve mitral isthmus flutter ablation by radiofrequency: the SHERIFF plan.

Achieving mitral isthmus (MI) block can be challenging. This prospective study evaluated the feasibility and efficacy of a systematic strategy comprising three consecutive steps to achieve MI block. Twenty consecutive patients (mean (± SD) age 71.4 ± 6.98 years) undergoing ablation of perimitral atrial tachycardia (PMAT) between December 2019 and November 2021 were included. MI was ablated using a systematic strategy comprising up to three consecutive steps: (1) endocardial ablation from the superolateral mitral annulus to the left pulmonary veins; (2) additional epicardial ablation in the coronary sinus (CS) on the opposite side of the endocardial line; and (3) ablation of early activation sites between endocardial and epicardial breakthroughs. MI block was successfully achieved in 19/20 patients (95%). MI block after endocardial radiofrequency ablation alone (step 1) was observed in 7/20 patients (35%). Epicardial ablation within the CS on the other side of the endocardial line (step 2) resulted in bidirectional MI block in three more patients. Endocardial ablation of epicardial conduction was successful for nine additional patients (95% success). At the 12-month follow-up, five patients (25%) displayed recurrence of arrhythmia after a single procedure. One patient had electrical cardioversion for persistent atrial fibrillation. Four patients had a redo procedure for left atrial flutter and only two patients (10%) had conduction across the MI and showed recurrence of PMAT. No complications occurred. The three-step ablation strategy resulted in a high rate of acute and durable MI block. PMAT recurrence after a single procedure was 10% at 1-year follow-up.

Conduction time around the mitral valve annulus has the potential to rule out postablation perimitral atrial tachycardia.

It would be helpful in determining ablation strategy if the occurrence of perimitral atrial tachycardia (PMAT) could be predicted in advance. We investigated whether estimated perimitral conduction time (E-PMCT), namely, twice the time between coronary sinus (CS) pacing and the ensuing wave-front collision at the opposite side of the mitral annulus, correlated with the cycle length of PMAT and could predict future PMAT. We retrospectively (retrospective cohort) and prospectively (validation cohort) investigated atrial fibrillation patients who had received pulmonary vein isolation (PVI) and in whom left atrial maps had been created during CS pacing. We calculated their E-PMCT. PMAT was observed either by provocation or during follow-up in 25, AT other than PMAT was observed in 24 (non-PMAT AT group), and 53 patients never displayed any AT (no-AT group) in the retrospective cohort. In the PMAT group of the retrospective cohort, a strong positive correlation was observed between the PMAT CL and E-PMCT (r = .85, p < 0.001). PMAT was never induced nor observed in patients with E-PMCT less than 176 ms, and the best cut-off value for PMAT was 180 ms by receiver-operating characteristic curve analysis. In the validation cohort of 76 patients, the cut-off value of the E-PMAT less than 180 ms predicted noninducibility of PMAT, with a sensitivity of 78.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25.0%. Short E-PMCT may predict noninducibility of PMAT and guide a less invasive ablation strategy.

Conduction time around the mitral valve annulus could predict the incidence of peri-mitral atrial tachycardia

Abstract Background Empirical ablation for mitral isthmus (MI) for AF patient is sometimes challenging for its complex anatomy and wall thickness. It would be helpful in determining the ablation strategies if it could be predicted in advance that peri-mitral atrial tachycardia (PMAT) would occur. Using 3D mapping, a method to confirm MI block has been reported using E-PMCT (estimated peri-mitral conduction time: the doubling the time between coronary sinus (CS) pacing and the wave-front collision at the opposite side of the mitral annulus). Purpose We investigated whether E-PMCT correlated with cycle length of PMAT and was involved in the establishment of PMAT. Methods We retrospectively investigated the AF patients who were created the LA map during CS pacing with multipolar mapping catheter which could measure E-PMCT after pulmonary vein isolation. Amon these cases, 1) PMAT was observed spontaneously or induced (PMAT group, N=25, 68.6±10.9 years old, male 15) and none of the AT occurred by the provocation test and during follow up (no-AT group, N=53, 65.2 years old , male 38) were analyzed. In these group, we evaluated the relationships between E-PMCT and tachycardia circuit of PMAT. Results E-PMCT was significantly longer in PMAT group than non-AT group(216.5±30ms vs 166.7ms, p&amp;lt;0.005). Strong positive correlation was observed between cycle length of PMAT and E-PMCT (Person’s r=0.85, p&amp;lt;0.001). PMAT was non induced in patients with E-PMCT less than 176ms. According to the ROC curve, AUC for the detection of the non-AT group was 0.908 (95% CI 0.843-0.974, sensitivity 91.7%, specificity 81.1%) with the cut off value E-PMCT less than 180ms. The slow conduction during CS pacing were consistent with slow conduction during PMAT in this study. Although left atrial diameter, ejection faction, type of AF(paroxysmal or not), low voltage area in the left atrium and mitral annulus size in 3D mapping system was also different between PMAT group and non-AT group in the univariate analysis, E-PMAT was strongest predicter of occurrence of PMAT in multivariate analysis. Conclusion E-PMCT obtained after PVI could predict the non-inducibility of PMAT and was helpful to decision making for ablation strategy.

Efficacy and feasibility of vein of Marshall ethanol infusion during persistent atrial fibrillation ablation: A systematic review and meta-analysis.

Catheter ablation (CA) is currently used to treat persistent atrial fibrillation (PeAF). However, its effectiveness is limited. This study aimed to estimate the effectiveness of the vein of Marshall absolute ethanol injection (VOM-EI) for PeAF ablation. Adjunctive vein of Marshall ethanol injection (VOM-EI) strategies are more effective than conventional catheter ablation (CA) and have similar safety outcomes. We extensively searched the literature for studies evaluating the effectiveness and safety of VOM-EI + CA compared with CA alone. The primary endpoint was the rate of acute bidirectional block of the isthmus of the mitral annulus (MIBB). The secondary endpoints were atrial fibrillation (AF) or atrial tachycardia (AT) recurrence over 30seconds after a 3-month blanking period. Weighted pooled risk ratios (RRs) and corresponding 95% confidence intervals (CIs) were calculated using a random effects model. Based on the selection criteria, nine studies were included in this systematic review, including patients with AF (n = 2508), persistent AF (n = 1829), perimitral flutter (n = 103), and perimitral AT (n = 165). There were 1028 patients in the VOM-EI + CA group and 1605 in the CA alone group. The VOM-EI + CA group showed a lower rate of AF/AT relapse (RR = 0.70; 95% CI = 0.53-0.91; p = .008) and a higher rate of acute MIBB (RR = 1.29; 95% CI = 1.11-1.50; p = .0007) than the CA alone group. Our meta-analysis revealed that adjunctive VOM-EI strategies are more effective than conventional CA and have similar safety outcomes.

Abnormal Atrial Potentials Recorded During Sinus Rhythm or Pacing Represent Substrates for Reentrant Atrial Tachycardia.

Abnormal atrial potentials (AAPs) recorded during sinus rhythm/atrial pacing may indicate areas of slow conduction capable of supporting reentrant atrial tachycardia (AT). Therefore, we sought to examine the relationship between AAPs and AT circuits. One hundred twenty-three reentrant ATs in 104 patients were analyzed. AAPs, consisting of fragmented potentials and split potentials, were assessed using the Rhythmia LUMIPOINT algorithm. There was 93±13% overlap between areas with AAPs during sinus rhythm/atrial pacing and areas of slow conduction along the reentry circuit during AT. The cumulative area of AAPs was smaller in patients with localized-reentrant ATs compared with anatomic macro-reentrant ATs (20.0 [14.6-30.5] versus 28.9 [21.8-35.6] cm2; P=0.021). Patients with perimitral ATs had larger areas of AAPs on the lateral wall whereas patients with roof-dependent ATs had larger areas of AAPs on the roof and posterior wall (P≤0.018 for all comparisons). The patchy scar that was associated with localized-reentrant AT exhibited a larger area of AAPs at its periphery than the scar that did not participate in localized-reentrant AT (3.1 [2.4-4.5] versus 1.0 [0.7-1.6] cm2; P<0.001). AAPs recorded during sinus rhythm/atrial pacing are associated with areas of slow conduction during reentrant AT. The burden and distribution of AAPs may provide actionable insights into AT circuit features, including in cases in which ATs are difficult to map.

Vein of Marshall ethanol infusion: First-step or adjunctive choice for perimitral atrial tachycardia?

Perimitral atrial tachycardia (PMAT) is the most frequent type of iatrogenic atrial tachycardia (AT) after atrial fibrillation (AF) ablation. Vein of Marshall ethanol infusion (EIVOM) is a promising technique in mitral isthmus (MI) ablation. A total of 165 patients with PMAT were divided into three groups according to ablation strategies, including RF only group (n=89), RF-EIVOM group (initial RF ablation with adjunctive EIVOM, n=28), and EIVOM-RF group (first-step EIVOM with touch-up RF ablation, n=48). Acute and follow-up procedure outcomes were evaluated. PMAT terminated in 89.9%, 89.3%, and 93.7% of patients in RF only, RF-EIVOM and EIVOM-RF groups, respectively (p=.715), with complete MI block achieved in 80.9%, 89.3%, and 95.8% of patients (EIVOM-RF vs. RF only, p=.012). First-step utilization of EIVOM was associated with a significant shortening of RF ablation time at MI (EIVOM-RF 2.1±1.3min, RF only 7.9±5.9min, RF-EIVOM 6.8±5.8min; p<.001) and a decrease in the proportion of patients need ablation within coronary sinus (CS, EIVOM-RF 14.6%, RF only 61.8%, RF-EIVOM 64.3%; p<.001). After a mean follow-up of 12.1±6.2 months, AF/AT recurred in 39 (43.8%), 6 (21.4%), and 12 (25.0%) patients in RF only, RF-EIVOM, and EIVOM-RF group (RF-EIVOM vs. RF only, p=.026; EIVOM-RF vs. RF only, p=.022). EIVOM was associated with an enhanced acute MI block rate as well as reduced AF/AT recurrence. First-step utilization of EIVOM promises to significantly simplify the RF ablation process. PMAT is the most common type of iatrogenic AT after AF ablation procedures. EIVOM contributed to a higher acute MI block rate and lower arrhythmia recurrence risk during follow-up. First-step utilization of EIVOM significantly reduced the need for radiofrequency ablation at MI and inside CS with the advantage of creating a homogenous, transmural lesion and eliminating epicardial connections.

Mapping and ablation of left atrial roof-dependent tachycardias using an ultra-high resolution mapping system

BackgroundLeft atrial roof-dependent tachycardias (LARTs) are common macroreentrant atrial tachycardias (ATs). We sought to characterize clinical LARTs using an ultra-high resolution mapping system.MethodsThis study included 22 consecutive LARTs in 21 patients who underwent AT mapping/ablation using Rhythmia systems.ResultsThree, 13, 4, and 2 LART patients were cardiac intervention naïve (Group-A), post-roof line ablation (Group-B), post-atrial fibrillation ablation without linear ablation (Group-C), and post-cardiac surgery (Group-D), respectively. The mean AT cycle length was 244 ± 43 ms. Coronary sinus activation was proximal-to-distal or distal-to-proximal in 16 (72.7%) ATs. The activation map revealed 13 (59.1%) clockwise and 9 (40.9%) counter-clockwise LARTs. A 12-lead synchronous isoelectric interval was observed in 10/19 (52.6%) LARTs. The slow conduction area was identified on the LA roof, anterior/septal wall, and posterior wall in 18, 6, and 2 ATs, respectively. Twenty concomitant ATs among 13 procedures were also eliminated, and peri-mitral AT coexisted in 7 of 9 non-group-B patients. In group-B, the conduction gap was predominantly located on the mid-roof. Sustained LARTs were terminated by a single application and linear ablation in 6 (27.3%) and 9 (40.9%), while converting to other ATs in 7 (31.8%) LARTs. Complete linear block was created without any complications in all, however, ablation at the mid-posterior wall was required to achieve block in 4 (18.2%) procedures. During 14.0 (6.5–28.5) months of follow-up, 17 (81.0%) and 19 (90.5%) patients were free from any atrial tachyarrhythmias after single and last procedures.ConclusionsThe LART mechanisms were distinct in individual patients, and elimination of all concomitant ATs was required for the management.

Perimitral atrial tachycardias dependent on residual nonligament of Marshall conduction.

Catheter ablation for perimitral atrial tachycardia (PMAT) that persists despite lateral mitral isthmus (LMI) ablation is challenging. The aim of this study was to identify the role of the ligament of Marshall (LOM) in PMATs that persist after LMI conduction block has been created, and evaluate the validity of ethanol infusion into the vein of Marshall (VOM) as treatment. Sixteen consecutive PMATs in 13 patients that persisted despite apparent LMI conduction block, which was confirmed by ultrahigh-resolution mapping and entrainment pacing along the mitral annulus, were analyzed. PMATs were classified into two types based on the location of the endocardial breakthrough site: those utilizing the LOM (n = 13), which had a breakthrough site along with the LOM, and those not utilizing the LOM (n = 3), which had a breakthrough site at an anterior or posterior side of the LOM. Of the 16 PMATs, 5 PMATs (31%) were not suitable for ethanol infusion into the VOM because the LOM was not involved in the tachycardia circuit or because of the anatomy of the VOM. Fourteen PMATs (88%) were successfully terminated solely by breakthrough site ablation. At a mean follow-up period of 12 ± 9 months, 10 (77%) patients have remained free from atrial tachyarrhythmias. In cases of PMAT following LMI ablation, epicardial conduction over the LMI can occur independently of the LOM. Ethanol infusion into the VOM in such cases would not abolish residual epicardial conduction. The anatomy of the VOM can also preclude the use of this method.

An improved window of interest for electroanatomical mapping of atrial tachycardia

PurposeDiagnosis of atrial tachycardia (AT) with 3D mapping system remains challenging due to fibrosis or previous ablation. This study aims to evaluate a new electroanatomical mapping annotation setting using a window of interest adjusted at the end of the P wave (WOIp wave) to identify the AT mechanism more accurately.MethodsTwenty patients with successful ablation of left AT using navigation system CARTO3 were evaluated. Two maps for each patient were generated offline using either conventional settings of WOI (WOIconv.) or WOIp wave. Three investigators from two centres analysed the maps blindly.ResultsMechanisms of AT were macroreentrant in 14/20 patients (70%) and focal in 6/20 (30%). WOIp wave resulted in a significant increase in the percentage of correct identification of the mechanism based on mapping alone (93.3 ± 13.7% vs 58.3 ± 33.9%; p = 0.0003) compared with WOIconv.. Diagnoses based on mapping were arrived at faster (27.8 ± 16.4 s vs 38.97 ± 13.64 s, respectively; p = 0.0231) and with a greater confidence in the diagnosis (confidence index 2.57 ± 0.45 vs 2.12 ± 0.45, respectively; p = 0.0024). With perimitral re-entry specifically “early meets late” was closer to the anatomical region of the mitral isthmus (15.9 ± 20.9 mm vs 48.77 ± 23.23 mm, respectively; p = 0.0028).ConclusionsThis study found that electroanatomical mapping acquisition with a window of interest set at the end of the P wave improves the ability to diagnose the arrhythmia mechanism based on the initial map. It is particularly beneficial in identifying area of interest for ablation in perimitral AT.

An improved window of interest for electroanatomical mapping of atrial tachycardia

Diagnosis of atrial tachycardia (AT) with 3D mapping system remains challenging due to fibrosis or previous ablation. This study aims to evaluate a new electroanatomical mapping annotation setting using a window of interest (WOI) adjusted at the end of the P-wave to identify the AT mechanism more accurately. Twenty patients with successful ablation of left AT using navigation system CARTO3 were evaluated. Two maps for each patient were generated offline using either conventional settings of WOI or WOI set at the end of the P-wave. Three investigators from two centres analysed the maps blindly. Mechanisms of AT were macroreentrant in 14/20 patients (70%) and focal in 6/20 (30%). WOI set at the end of the P-wave resulted in a significant increase in the percentage of correct identifications of the mechanism in 93.3 ± 13.7% vs. 58.3 ± 33.9% ( P = 0.0003) with conventional WOI. Diagnoses were performed significantly faster (27.8 ± 16.4s vs. 38.97 ± 13.65s, respectively; P = 0.0231) and with a greater confidence in the diagnosis (confidence index 2.56 ± 0.46 vs. 2.12 ± 0.45, respectively; P = 0.0024). Interestingly, in perimitral AT maps obtained with the investigational setting, “early meets late” were located closer to the anatomical region of the mitral isthmus (15.9 ± 20.9 mm vs. 48.77 ± 23.23 mm, respectively; P = 0.0028). This study found that electroanatomical mapping acquisition with a WOI set at the end of the P-wave improves the ability to diagnose the arrhythmia mechanism. It is particularly beneficial in identifying perimitral ATs.

Mapping and ablation of clinical spontaneous perimitral atrial tachycardias using an ultra–high-resolution mapping system

Perimitral atrial tachycardias (PMATs) are common atrial tachycardias (ATs), yet their mechanisms vary. The purpose of this study was to characterize clinical spontaneous PMATs using an ultra-high-resolution (UHR) mapping system. The study included 32 consecutive PMATs in 31 patients who had undergone AT mapping/ablation using a UHR mapping system. Six, 10, 11, and 5 PMATs occurred in cardiac intervention-naïve (group A), post-lateral/posterior mitral isthmus linear ablation (group B), post-atrial fibrillation ablation without mitral isthmus linear ablation (group C), and post-cardiac surgery (group D) patients, respectively. Group A patients tended to be older, more likely were female, and had sinus node or atrioventricular conduction disturbances more frequently. A 12-lead synchronous isoelectric interval was observed in 15 PMATs (46.9%). Coronary sinus activation was proximal to distal or distal to proximal except in 3 PMATs with straight patterns due to epicardial gaps. Left atrial anterior/septal wall (LAASW) low-voltage areas were smallest in group B. Slow conduction areas (SCAs) were identified in 26 PMATs (81.2%) and were located on the LAASW in all group A and group D patients. Conduction velocity in the SCAs was slowest in group B. In group B, all PMATs were terminated by single applications, and the gaps were located epicardially in 5 of 10 (50%). Anterior (n = 23) or lateral/posterior (n = 9) mitral isthmus linear block was successfully created without any complications in all. Twenty-five concomitant ATs among 18 patients (58.1%) also were eliminated. During a median of 20.0 (11.0-40.0) months of follow-up, 28 patients (90.3%) were free from any atrial tachyarrhythmias. An UHR mapping-guided approach with identification of the individual tachycardia mechanism should be the preferred strategy given the distinct and complex arrhythmia mechanisms.

Ethanol infusion into the vein of Marshall for recurrent perimitral atrial tachycardia after catheter ablation for persistent atrial fibrillation.

Catheter ablation of perimitral atrial tachycardia (PMAT) is challenging. Epicardial conduction of the Marshall bundle (MB) across the mitral isthmus (MI) remains an important cause of recurrent tachycardia. The role of ethanol infusion into the vein of Marshall (EI-VOM) for PMAT has not been fully elucidated. The study enrolled 28 consecutive patients with recurrent PMAT after atrial fibrillation (AF) ablation. Conventional PMAT (group 1, n=15) and MB-related PMAT (group 2, n=13) were diagnosed by detailed activation mapping and entrainment mapping. VOM venography and EI-VOM were first performed, and additional ablation was performed if necessary. The VOM was accessible in 24 (85.7%) patients (12 [80%] in group 1 and 12 [92.3%] in group 2). Patients with MB-related PMAT were more responsive to EI-VOM (as shown by PMAT termination or tachycardia cycle length prolongation) (92.4%vs 53.3%, P=.038). In the 16 patients requiring additional ablation after EI-VOM, all residual MI conduction gaps were located on the annular side of the MI. At the end of the procedure, MI bidirectional block was achieved in 14 (93.3%) patients in group 1 and in 12 (92.3%) patients in group 2 (P=1.000). After a mean follow-up of 7.5 ± 3.1 months, three (10.7%) patients had recurrent AT. EI-VOM is feasible and effective in the treatment of PMAT after AF ablation, especially in patients with MB-related PMAT.

The role of Marshall bundle epicardial connections in atrial tachycardias after atrial fibrillation ablation

Atrial tachycardias (ATs) are often seen in the context of atrial fibrillation (AF) ablation. To evaluate the role of the Marshall bundle (MB) network in left atrial (LA) ATs using high-density 3-dimensional mapping. A total of 199 ATs were mapped in 140 patients (112 male, mean age: 61.8 years); 133 (66.8%) were macroreentrant and 66 (33.2%) were scar-related reentry circuits. MB-dependent ATs were suggested by activation mapping analysis and confirmed with entrainment along the circuit. The MB network participated in 60 (30.2%) reentrant ATs: 31 perimitral ATs (PMATs) and 29 localized reentry circuits. Of 60 MB-related ATs, 49 (81.6%) terminated with radiofrequency (RF) ablation: 44 (73.3%) at the MB-LA junction and 5 (8.3%) at the MB-coronary sinus (CS) junction, while 9 (15%) terminated after 2.5-5 cc of ethanol infusion inside the vein of Marshall (VOM). Of the 31 PMATs, 17 (54.8%) terminated at the MB-LA junction, 5 (16.1%) at the MB-CS junction, and 7 (22.6%) with ethanol infusion. Of the 29 localized reentry circuits using the MB, 27 (93.1%) terminated at the MB-LA junction, none at the MB-CS junction, and 2 (6.9%) after ethanol infusion. Recurrences were mostly observed after RF ablation (18 of 37 patients, 49%) compared to ethanol infusion (1 of 9 patients, 11%) (P = .06). MB reentrant ATs accounted for up to 30.2% of the left ATs after AF ablation. Ablation of the MB-LA or CS-MB connections or ethanol infusion inside the VOM is required to treat these arrhythmias.

Characteristics of Marshall bundle-related atrial tachycardias using an ultrahigh-resolution mapping system.

Marshall bundle (MB)-related atrial tachycardias (ATs) have already been described; however, their characteristics using an ultrahigh-resolution mapping system are not yet well known. The purpose of this study was to clarify the characteristics of MB-related ATs with ultrahigh-resolution mapping. In 28 patients who underwent an electrophysiological study for ATs using an ultrahigh-resolution mapping system, precise circuits of 37 ATs were detected. Among those ATs, five were diagnosed as MB-related ATs that had epicardial connections among the reentrant circuits (mean age 76.6 ± 3.7years, one male patient). We analyzed the characteristics of those MB-related ATs with ultrahigh-resolution mapping. The mean cycle length was 260 ± 60ms, and the total acquired electrograms were 12,962 ± 2616 points. Two ATs were perimitral ATs, two rotated around the left pulmonary vein (PV), and one rotated around the left inferior PV. All ATs had a centrifugal activation pattern: 5 o'clock on the mitral annulus in four ATs and the upper ridge in one. Tiny potentials, which indicated epicardial potentials covering the cycle length, were detected in four of five ATs. The local activation times covered over 95% of the tachycardia cycle length on the endocardial side only in all ATs. All ATs were terminated during a radiofrequency ablation from the endocardial side of the Marshall bundle. The ultrahigh-resolution mapping system demonstrated an activation map of MB-related ATs with a centrifugal pattern. Macroreentrant tachycardias with a centrifugal activation pattern should be considered as possible MB-related ATs.

Importance of the vein of Marshall involvement in mitral isthmus ablation.

Epicardiac conduction via the vein of Marshall (VOM) can bypass the mitral isthmus (MI) line, making MI ablation difficult. This study aimed to assess the contribution of the VOM in achieving MI conduction block. This study included 143 consecutive patients with nonparoxysmal atrial fibrillation who underwent initial MI ablation. They were retrospectively classified into two groups, a VOM-guided group (n=28) and a conventional group (n=115), according to the use of a 2-Fr electrode catheter inserted in the VOM. The acute success rate of achieving MI block and the ablation data were assessed. When the bidirectional block was verified exclusively in the VOM or coronary sinus (CS) electrodes, we defined it as a pseudo MI block. In the VOM-guided group, we ascertained the complete MI block, verified both in the VOM and CS electrodes. In the VOM-guided group, the pseudoblock was observed in 33.3% of the patients during MI ablation. With significantly less radiofrequency energy (19322.6±11352.8vs 25389.3±19 951.9, P=0.04), we achieved a similar level of success rate in MI ablation in the VOM-guided group (96.4%vs 91.3%, P=0.36). Notably, after achieving complete MI block, atrial burst pacing induced two perimitral flutters in the VOM-guided group, which were successfully terminated by the additional radiofrequency application. Assessment of electrical conduction through the VOM could clarify the existence of a pseudo MI conduction block. However, the existence of a slow conduction through the MI could be detected only after induction of perimitral atrial tachycardia with atrial programmed stimulation.

Revisiting anatomic macroreentrant tachycardia after atrial fibrillation ablation using ultrahigh-resolution mapping: Implications for ablation

Anatomic macroreentrant atrial tachycardias (MATs) are conventionally reported to depend on the cavotricuspid isthmus, the mitral isthmus, or the left atrial roof, and are commonly seen following catheter ablation for atrial fibrillation. To define the precise circuits of anatomic MAT with ultrahigh-resolution mapping. In 57 patients (mean age, 62 years; 10 female) who developed ≥1 anatomic MAT, we analyzed 88 MAT circuits including 16 peritricuspid, 42 perimitral, and 30 roof-dependent circuits, using high-density mapping and entrainment. Of 16 peritricuspid atrial tachycardias (ATs), 8 (50.0%) showed a circuit not limited to the tricuspid annulus. However, cavotricuspid isthmus ablation terminated the tachycardia in all patients. Similarly, 26 of 42 perimitral ATs (61.9%) showed a circuit not limited to the mitral annulus, and a low-voltage zone <0.1 mV around the mitral annulus was associated with nontypical perimitral ATs (P < .0001). The practical isthmus was not in the mitral isthmus in 13 of these 26 perimitral ATs (50%). Finally, 22 of 30 roof-dependent ATs (73.3%) had a circuit not rotating around both pairs of pulmonary veins. Brief assessment of the activation direction on the posterior wall in relation to that on the septal, anterior, and lateral wall helped deduce the circuit of roof-dependent AT in 27 of 30 (90.0%). Practical isthmus was not in the roof in 8 of 22 (36.4%). Practical isthmuses mapped with the system were significantly shorter than the usual anatomic isthmuses (16.1 ± 8.2 mm vs 33.7 ± 10.4 mm) (P < .0001). High-density mapping successfully identified the precise circuits and the practical isthmus of anatomic MATs in patients with prior atrial fibrillation ablation.

High-density activation mapping during perimitral atrial tachycardia demonstrates epicardial connection through the vein of Marshall

High-density activation mapping during perimitral atrial tachycardia demonstrates epicardial connection through the vein of Marshall

Useful Electrocardiographic Features to Help Identify the Mechanism of Atrial Tachycardia Occurring After Persistent Atrial Fibrillation Ablation

The purpose of this study was to describe and identify useful electrocardiographic characteristics to helpidentify the mechanism of atrial tachycardia (AT) occurring after persistent atrial fibrillation (PsAF) ablation. Electrocardiographic analysis to help identify the mechanism of AT after PsAF ablation is much limitedby the fact that remodeling and ablation alter the normal activation pattern. All consecutive patients who underwent mapping and ablation of AT after PsAF ablation were included.Surface P waves were analyzed during higher (>2:1) grades of atrioventricular block. One hundred ninety-six ATs with visible P waves were identified in 127 patients (macro-re-entry in 57%, centrifugal AT in 43%). One-third displayed low-voltage P waves (≤0.1 mV). An isoelectric line >80 ms was more common in centrifugal compared with macro-re-entrant AT (47% vs. 24%; p< 0.001), but its positive predictive value was limited (60%). A minority of peritricuspid ATs displayed the classic saw-tooth pattern (27% [n= 22]). However, the "precordial transition" (a gradual transition from an upright component in lead V1 to a negative component with progression across the precordium) remained often observed and specifically identified peritricuspid AT (specificity, 98%; sensitivity, 59%). Only 2 unique features could help identify perimitral AT (n= 60). First, the presence of a negative or negative-positive P-wave in any of leads V2 to V6 identified perimitral AT with 97% specificity and 30% sensitivity. Second, a "notched" negative component at the beginning of a positive P-wave in the inferior leads specifically identified clockwise perimitral AT (specificity, 98%; sensitivity, 25%). Only few unique electrocardiographic characteristics help identify the mechanism of AT afterPsAFablation.Knowledge of these characteristics may aid in planning and performing ablation.