Perimitral Atrial Flutter Research Articles

High efficacy and safety of endocardial pulsed electrical field ablation via contact force-controlled catheters for mitral isthmus ablation

Abstract Background A new technology of a pulsed field generator enables established contact force-controlled radiofrequency (RF) catheters to apply point by point monopolar pulsed electrical field (PEF) energy for linear lesions in atrial fibrillation (AF) ablation. Purpose We evaluated this novel monopolar PEF ablation technique for creating lateral mitral isthmus ablation lines in case of perimitral flutter or complex AF patients non responder to pulmonary vein isolation (PVI). Methods Patients (n=44, age 65±11 years) referred for ablation/re-ablation of AF with spontaneous or inducible perimitral atrial flutter (n=34, 77%) or persistent AF and severe enlarged atrium (n=7) or de novo longstanding persistent AF (n=3) without signs of atrial fibrosis were included in our patient cohort for lateral mitral isthmus ablation with PEF applications. After 3D high density voltage mapping of the left atrium with multipolar microelectrode catheters, and confirmation/completion of PVI, an endocardial lateral mitral isthmus line was performed. Using contact force sensing catheter, 25A PEF energy pulses were applied targeting a minimum of 10g contact force and an interlesion distance ≤5mm. Before PEF application 0.2 mg nitroglycerin was intravenously injected. If the inferolateral mitral isthmus line to the left inferior pulmonary vein could not be blocked, a more superior lateral line to the left superior pulmonary vein was performed. If the mitral isthmus could not be blocked by endocardial PEF application or conduction recurred after adenosine injection an additional epicardial ablation via RF application in the coronary sinus was performed. Results Exclusively endocardial PEF application blocked the lateral mitral line in 37 out of 42 cases (88%) with 23±14 PEF applications. After an unsuccessful inferior lateral mitral line, in 34% of cases a second superior lateral mitral line have to be performed. Only in five cases additional epicardial RF applications via coronary sinus were necessary to complete the mitral isthmus block. Block time between superior lateral mitral anulus and infero lateral coronary sinus was 196±48 ms. One pericardial tamponade which could be successfully drained, and no other serious complication occurred throughout all procedures (no ST segment elevation, no tamponade requiring surgery, no cerebrovascular event). Limited follow-up will be available at the time of presentation. Conclusion Blockade of left atrial mitral isthmus line with PEF application via contact force-sensing catheters for ablation of complex atrial fibrillation patients is very efficient and safe. Especially the high efficacy of exclusively endocardial PEF application for creation of a lateral mitral isthmus block in most patients is very promising. However, the long term permanence of the linear lines have to be awaited.

Dual linear lesions for right atrial flutter after mitral valve surgery via the superior transseptal approach.

The superior transseptal approach (STA) for mitral valve surgery is associated with a higher risk of developing macroreentrant incisional atrial flutter (AFL) than the left atrial approach. This study aimed to describe the linear lesions for the complex AFL circuit after the STA and to propose an option for the linear ablation target site. Of the 26 patients who underwent radiofrequency catheter ablation for AFL after mitral valve surgery, data from seven patients with STA incisions were retrospectively analyzed. All patients who had undergone the STA had incisional AFL rotated in a long loop within the right atrium (RA) and cavo-tricuspid isthmus (CTI)-dependent AFL. The linear lesions were created in the CTI, the superior RA vestibule, and between the RA-free wall incision or the septal incision and the inferior vena cava. Procedural success was achieved with dual linear lesions in the CTI and superior RA vestibule. Two of seven patients had AFL recurrence during a mean observation period of 22.5 ± 16.7months. The circuits of recurrent AFL were CTI-dependent AFL and perimitral AFL, respectively. No AFL recurrence was noted with reconduction of the superior RA vestibular lesion. Dual linear lesions in the CTI and superior RA vestibule are an effective treatment option for RA macroreentrant AFL after the STA.

Arrhythmic substrate in pulmonary vein isolation reprocedures in the era of the close protocol

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The CLOSE protocol was developed as a radiofrequency ablation strategy that would result in the safe creation of durable pulmonary vein isolation (PVI) leading to improved outcomes. The aim of the protocol is to enclose the PVs with stable, contiguous and ablation index (AI) guided lesions. Purpose We analyze the arrhythmic substrate found in patients undergoing PVI reprocedure after a first CLOSE-PVI procedure and compare it to that observed in PVI reprocedure in patients who underwent a first non-CLOSE-PVI procedure. Methods Patients undergoing a PVI-reprocedure after a first CLOSE-PVI procedure (35W, AI 450 for the anterior wall and 350 for posterior wall) were prospectively included (CLOSE-group). During the reprocedure a detailed electroanatomical map with multielectrode catheters was obtained in all patients. The number of reconnected PVs and segments was assessed. In patients with left atrial flutter (AFl), the circuit was defined by activation and entrainment mapping. These data were compared to those observed in a historic control group of PVI reprocedures after a first non-CLOSE-PVI procedure (non-CLOSE-group; 21 reprocedures among 157 first PVI procedures). Results Among 352 patients undergoing a first CLOSE-PVI, 27 (74.1% male, 57±8.6 years) underwent a PVI reprocedure. 74% (20 patients) showed at least 1 PV reconnected vs 100% in non-CLOSE group; p=0.012. Among the 7 patients without PV reconnection (PVR) perimitral AFl was found in 2 patients and a roof dependent AFl was observed in 1 patient. In the remaining 4 patients no specific substrate or trigger was observed. Among patients showing PVR, no differences were observed in terms of mean number of reconnected PVs [2(1-2) vs 2(1-3) respectively; p=0.751] or segments [2(1-2) vs 2(2-4) respectively; p=0.895) compared to the non-CLOSE group. Conclusion PVR remains the main substrate in patients undergoing atrial fibrillation (AF) ablation reprocedure after a first CLOSE-PVI. However, a significantly higher proportion of patients showed persistent PVI without a specific arrhythmic substrate or trigger for AF; which makes it necessary to define new strategies to improve rhythm control in these patients.

Change of Peri-mitral Atrial Flutter into Single-loop Biatrial Flutter During Ablation

Anterior line ablation for peri-mitral atrial flutter (AFL) is associated with biatrial flutter due to disruption of the electrical conduction in the left atrial septum. An AFL case with valvular disease, cardiac surgery, and prior ablation was confirmed to be counterclockwise peri-mitral flutter with isthmus on the left atrial septum. Ablation on the septum of the left atrium (LA) targeting the isthmus prolonged the tachycardia cycle length (TCL) from 266 to 286 ms. Left atrial mapping during AFL with a TCL of 286 ms showed that the activation remained peri-mitral counterclockwise, but there was interruption of the local activation time (LAT) sequence. Combined mapping of the LA and the right atrium (RA) showed a counterclockwise single-loop biatrial flutter, involving the whole LA and the RA septum, with Bachmann's bundle and the posteroinferior septum being the interatrial connections. The AFL was terminated by ablation at the right superior cavoatrial junction. RA mapping should be considered if there is prolongation of TCL but without termination of the peri-mitral AFL, and if there is interruption of the continuity of the LAT sequence during AFL with a longer TCL. The biatrial flutter can be terminated by ablation targeting the interatrial connections.

Electrophysiological characteristics of epicardial breakthrough during catheter ablation of perimitral atrial flutter.

Unsuccessful endocardial ablation for perimitral atrial flutter (AFL) could be attributed by the epicardial bridging. This study aimed to investigate the electrophysiological characteristics of epicardial breakthrough during catheter ablation of perimitral AFL. This retrospective study recruited 40 patients who received successful catheter ablation of perimitral AFL from January 2016 to June 2021. The patients were divided into two groups: group 1 (n = 18) successful endocardial ablation, and group 2 (n = 22) successful epicardial ablation following unsuccessful endocardial ablation owing to incomplete mitral block or unachievable termination AFL. The local electrogram (EGM) interval of coronary sinus (CS) duration perimitral AFL was measured before catheter ablation. There was no significant difference in the baseline characteristics between the two groups. In group 2, 60% of successful epicardial ablation was performed in intra-CS ablation and 40% in VOM ethanol infusion. Group 2 patients had a longer EGM interval of distal CS than that in group 1 (CS1-2: 64.2 17.5 vs. 42.4 0.09 ms, P = 0.008, CS3-4: 57.13 19.4 vs. 43.8 7.5 ms; P = 0.001). The conduction velocity at successful site was slower in group 2 compared to group 1 (0.18 0.05 vs. 0.75 0.19 m/s, P = 0.040). In the multivariate analysis, distal EGM interval (CS1-2) was identified as independent predictor of the need of epicardial ablation with the optimal cutoff of 49 ms. Longer EGM interval in distal CS during perimitral AFL was observed in perimitral AFL patients with epicardial breakthrough following endocardial-failed ablation, which may be associated with the need of epicardial ablation.

Automated conduction velocity estimation based on isochronal activation of heart chambers

BackgroundSpatial differences in conduction velocity (CV) are critical for cardiac arrhythmias induction. We propose a method for an automated CV calculation to identify areas of slower conduction during cardiac arrhythmias and sinus rhythm.MethodsColor-coded representations of the isochronal activation map using data coming from the RHYTHMIA™ Mapping System were reproduced by applying a temporal isochronal window at 20 ms. Geodesic distances of the 3D mesh were calculated using an algorithm selecting the minimum distance pathway (MDP). The CV estimation was performed considering points on the boundary of two spatially and temporally adjacent isochrones. For each of the boundary points of a given isochrone, the nearest boundary point of the consecutive isochrone was chosen, the MDP was evaluated, and a map of CV was created. The proposed method has been applied to a population of 29 patients.ResultsIn all cases of perimitral atrial flutter (16 pts out of 29 (55%)), areas with significantly low CV (< 30 cm/s) were found. Half of the cases present regions with low CV located in the anterior wall. No case with low CV at the so-called LA isthmus was observed. Right atrial maps during common atrial flutters showed low CV areas mainly located in the inferior inter-atrial septum. No areas of low CV were observed in subjects without a history of atrial arrhythmia while pts affected by paroxysmal AF showed areas with a limited extension of low CV.ConclusionsThe proposed software for automated CV estimation allows the identification of low CV areas, potentially helping electrophysiologists to plan the ablation strategy.

Endocardial ablation at the mitral valve vestibule and its surroundings for the treatment of arrhythmias linked to the greater cardiac vasculature.

The role of the epicardial vasculature in supraventricular and ventricular arrhythmias was described in clinical studies as well as its treatment by intravascular point ablation or alcohol injection. We report on a case series of patients with different arrhythmias linked to an epicardial site of origin with evidence supporting transmural extensions that were targeted for ablation with successful outcomes. The records of patients who has catheter ablation for Supraventricular or Ventricular arrhythmias between 2015 and 2020 was searched for patients with (1) arrhythmias linked to the epicardial vasculature and (2) findings to support an endocardial connection to the epicardial vasculature by activation mapping, pace mapping, or differential pacing, and (3) were successfully ablated via an endocardial approach only. From the data searched, we identified five patients with the following arrhythmias left ventricular summit ectopy, peri-mitral atrial flutter, preexcitation with inducible atrioventricular reentry tachycardia (AVRT), and a concealed left side accessory pathway with inducible AVRT that were linked to the following vessels: Great Cardiac vein, persistent left superior vena cava, left coronary cusp, and left ventricular outflow tract. Endocardial connections were supported by a combination of electro anatomical activation mapping, pace-mapping, and differential pacing. Endocardial ablations performed in all patients were successful without complications. This report highlights a subset of patients with arrhythmias linked to the greater cardiac vascular system that can be safely and effectively ablated endocardially, given the limitations and possible complications of epicardial ablation within or in the proximity of the epicardial vasculature.

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.

Catheter ablation with ethanol infusion in the vein of marshall for persistent atrial fibrillation: safety and procedure duration

Abstract Funding Acknowledgements Type of funding sources: None. Background Ethanol Infusion in the Vein of Marshall (EIVOM) has been recently introduced as an efficient technique that helps achieving mitral isthmus block during ablation procedures for persistent atrial fibrillation (PAF) or peri-mitral atrial flutter. Purpose We have evaluated the safety of EIVOM and the duration required to perform this procedure. Methods We performed EIVOM in 121 patients for PAF (mean age of 65 years (range 40-83, 73% men; Mean EF 50%. The main steps of the EIVOM were as follows: the procedure commenced with catheterization of the coronary sinus, followed by the subsequent introduction of an angiography catheter that allowed for iodine contrast injection and vein of Marshall (VOM) localization, 1.5-2.5 mm angioplasty balloon over 0.014" guidewire placement and finally the ethanol injection up to 10 ml. Results No major complications were observed during the ablation procedure or before hospital discharge. In 62 patients in whom procedure duration data was available the mean EIVOM procedure time was 41 min (range from 13 to 105 min). After the first 20 procedures, where the learning curve for the operators has to be taken into consideration, a reduction in the time required to achieve EIVOM was consistently noted, with an average of less than 30 min. and for the last 20 procedures less than 20 min. Factors which increase the time required for successful EIVOM include: difficulty in visualizing the ostium of the VOM, a VOM ostium located proximally, difficulty in advancing the angioplasty wire into the VOM and balloon displacement and repositioning. Conclusions Ethanol infusion in the Vein of Marshall is a safe and efficient technique that can be performed in an acceptable amount of time after an initial learning curve. Abstract Figure. Image 1 VOM

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

IntroductionAfter 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.MethodsSeventy‐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.ResultsMitral 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.ConclusionPerimitral 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.

Relationship between electrical gaps after Maze procedure and atrial tachyarrhythmias and ablation outcomes after cardiac surgery and concomitant Maze procedure.

Atrial tachycardia (AT) and atrial fibrillation (AF) commonly occur after cardiac surgeries (CSs). This study investigated the mechanisms and long-term outcomes of AT and AF ablation after various Maze procedures, particularly whether atrial tachyarrhythmias after the Maze procedure occur due to gaps in the Maze lines. We analyzed 37 consecutive cases with atrial tachyarrhythmias after the Maze procedures and concomitant CSs between 2007 and 2019. Fifty-nine atrial tachyarrhythmias were induced in 37 consecutive cases, and 49 of those atrial tachyarrhythmias were mappable ATs. Forty ATs were related to the Maze procedures in the 49 mappable ATs (81.6%). All 37 consecutive cases had residual electrical conductions (gaps) in the Maze lines (88 gaps; 2.4 ± 1.2 gaps/patient). Forty of 88 gaps (45.5%) were associated with gap-related ATs. The common ATs in this study were 1. peri-mitral atrial flutter due to gaps at pulmonary vein isolation (PVI) line to mitral valve annulus (MVA) (20 cases), and 2. peri-tricuspid atrial flutter due to gaps at right atrial incision to the tricuspid valve annulus (TVA) (10 cases). Forty-seven of 49 ATs (95.9%) were successfully ablated at the first session, and there were no complications. The mean follow-up period after ablation was 3.6 ± 3.2 (median, 2.1; interquartile range, 0.89-6.84) years. The Kaplan-Meier analysis of freedom from recurrent atrial tachyarrhythmias after Maze procedure was 82.7% at 1-year follow-up and 75.5% at 4-year follow-up after a single procedure. Reentry was the main mechanism of ATs after Maze procedures and concomitant CSs, and ATs were largely related to the gaps on the Maze lines between the PVI line and the MVA or those on the lines between right atrial incision to the TVA. Long-term follow-up data suggest that catheter ablation of atrial tachyarrhythmias after various Maze procedures is effective and safe.

Перший клінічний досвід виконання алкогольної абляції вени Маршалла в комплексному лікуванні персистентної фібриляції передсердь

This article describes the first in Ukraine clinical experience of alcohol ablation of Marshall’s vein in the complex interventional treatment of persistent atrial fibrillation (AF). Current scientific data suggest that when drug therapy is ineffective, ablation of AF substrate is a most important stage in the treatment of arrhythmia, as well as optimal method of control and prevention of further cardiovascular events. The standard treatment for paroxysmal AF is radiofrequency ablation (RFA) with electrical isolation of the pulmonary veins (PVI). However, due to the involvement of other pathogenetic mechanisms, a sole PVI is less effective in persistent forms of arrhythmia. For example, in persistent AF forms pathological electrical activity often occurs beyond the pulmonary veins. In particular, it can be observed in the area of ​​the posterior wall of the left atrium and mitral isthmus resulting in perimitral atrial flutter. RFA in this area can reduce the rate of arrhythmia recurrence. However, achieving a stable bidirectional conduction block in the area of ​​lateral mitral isthmus with endocardial RFA is technically challenging. An option to improve the effectiveness of RFA in this case, apart from epicardial RFA in the distal coronary sinus, is an alternative method, i.e. alcoholic ablation of Marshall’s vein by introducing ethanol into its lumen, occluded by a balloon. The presented clinical case shows combined variant of persistent AF minimally invasive treatment using alcoholic Marshall’s vein ablation and RFA with PVI target. Key words: atrial fibrillation, radiofrequency ablation, alcoholic ablation, Marshall vein, clinical case.

Partial participation of the coronary sinus owing to longitudinal dissociation during peri-mitral atrial flutter.

Partial participation of the coronary sinus owing to longitudinal dissociation during peri-mitral atrial flutter.

Catheter ablation of atrial arrhythmias in patients after thoracoscopic ablation of persistent atrial fibrillation

Aim. To determine the mechanisms of development and approaches to interventional treatment of postoperative atrial tachycardia in patients after thoracoscopic ablation (TA) of atrial fibrillation (AF). Material and methods . The results of thoracoscopic ablation of AF in 46 patients were analyzed, of which 19,5% (n=9) had atrial tachycardia after the procedure. Radiofrequency ablation (RFA) was conducted in these patients after a 3-month blanking period. Regardless of tachycardia type, the threedimensional reconstruction including high-density right and left atrial (LA) voltage mapping was performed in order to visualize the lesions, pulmonary veins and LA posterior wall isolations. After RFA and sinus rhythm restoration, re-mapping was performed to assess conduction block and absence of electrical activity in the lesion zones. Results. Complete pulmonary vein (PV) isolation was verified in 55,5% of patients (n=5). In 44,4% (n=4), there were residual PV fractionated potentials without conduction with LA. In 22,2% of subjects (n=2), we identified typical atrial flutter (AFL), which was terminated by RFA in cavotricuspid isthmus (CTI). There were 77,7% (n=7) of patients who were diagnosed with atypical LA flutter; 66,6% (n=6) of them had conduction reconnection at the thoracoscopic box-lesion line. Perimitral AFL with slow conduction zone which was located on the anterior wall of LA was verified in 11,1% of patients (n=1). The effective RFA was performed in these areas. Two main factors affecting failed ablation were LA volume and body mass index (BMI). In patients with arrhythmias after TA, LA volume was 180,2±35,6 ml vs 158,34±38,5 ml in patients with sinus rhythm. BMI was 30,8±3,1 kg/m2 and 28,9±3,9 kg/m2, respectively. The mean follow-up was 9,8±2,7 months. All patients after catheter ablation maintained a stable sinus rhythm. Conclusion. Atrial tachycardia after TA is caused by the gaps in box-lesion lines. The main predictors of gaps are high values of LA volume and BMI. The high-density mapping increases the effectiveness of RFA. Combination of epicardial and endocardial accesses is the most effective approach to treatment of patients with persistent AF.

P1417Short and long term efficiency of different therapeutic approaches to perimitral atrial flutter

Abstract Introduction Catheter ablation of perimitral flutter can be challenging, owing to difficult anatomy. The most commonly applied procedure is the creation of a mitral isthmus line (between the lower left pulmonary vein and the mitral anulus) or an anteroseptal line (between the upper right pulmonary vein and the anterior mitral anulus). Purpose Our study aimed to compare the short and long term efficacy of two different ablation methods. Methods In our retrospective study 45 consecutive patients diagnosed with perimitral flutter were included between 2009 and 2018. Results Radiofrequency ablation was performed in 48 cases in 31 patients (mitral isthmus line (n = 25, 52.1%); anteroseptal line (n = 23, 47.9%)). Arrhythmia-termination and sinus rhythm restoration could be achieved in 64.6% of the cases (mitral isthmus line: 16/25 (64.0%), anteroseptal line: 15/23 (65.2%). Comparing two different techniques, there was no significant difference (p = 0.85) in acute success rates. During 24.3 months of follow-up period, in 60.0% of the patients no recurrence occurred. The arrhythmia recurred in 6 cases (40.0%) after anteroseptal line ablation, and in 8 cases (53.3%) after mitral isthmus line ablation. No difference was found in the long term efficiency of two different ablation techniques (p = 0.211). Conclusion In our retrospective study we found no significant difference in the short and long term efficiency of two different therapeutic approaches to perimitral atrial flutter.

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.

Hybrid surgical ablation for persistent or long standing persistent atrial fibrillation: A French single centre experience

BackgroundHybrid ablation for the treatment of atrial fibrillation is a single combined procedure consisting in a minimally thoracoscopic surgical ablation followed by a catheter ablation. This promising technique is recommended in persistent atrial fibrillation according to the current guidelines but is not routinely performed in France, mainly due to the absence of reimbursement by the French National Health Insurance. AimsThe aim of this prospective and single-centre study was to analyse, for the first time in France, the feasibility, efficacy and complication rates of hybrid ablation in patients with persistent atrial fibrillation. MethodsHybrid ablation was performed in 15 consecutive patients (13 men, mean age 61±6 years) with persistent (7 patients) or long standing persistent (8 patients) atrial fibrillation. ResultsHybrid ablation was completed in 14/15 patients. Eleven patients returned in sinus rhythm during the procedure. Two patients (13%) had major per-procedural complications and 2 had minor complications. During an average follow-up of 25±6 months, 6 patients (40%) underwent a redo catheter ablation because of atrial tachycardia, mainly peri-mitral atrial flutter. At 1 year follow up, 14/15 patients were in sinus rhythm, including 11 free of antiarrhythmic drugs.

P977Selective liner ablation according to the type of tachycardia induced after pulmonary vein isolation in single-procedure for long-standing persistent atrial fibrillation

Abstract Background The most effective approach for long-standing persistent atrial fibrillation (LSPAF) ablation remained undetermined. Here, we hypothesized that selective linear ablation (SLA) according to the type of tachycardia induced by burst atrial pacing (BAP) after pulmonary venous isolation (PVI) in single-procedure reduces the recurrence. Methods A cohort of 66 LSPAF patients (Mean age 71.0±8.2 years, AF duration 40.5±58.8 months) who underwent PVI in single-procedure between April 2016 and November 2018 was evaluated. Results Any sustained atrial tachycardia (AT) or AF were not inducible by BAP after PVI in 21 patients (Non-inducible group, 31.8%, 71.3±7.9 years, 34.4±54.2 months). These patients underwent cavo-tricuspid isthmus (CTI) ablation after PVI. Forty-one patients underwent selective liner ablation according to the type of tachycardia induced by BAP after PVI (SLA group, 62.1%, 71.2±8.3 years, 39.3±55.6 months). Maccroreentry ATs (6 common atrial flutter, 5 AT originating from left atrial anterior wall, 2 peri-mitral atrial flutter, 1 roof-dependent atrial flutter) were induced by BAP in 14 patients of SLA group (73.2±19.7 years, 51.7±83.5 months). RF applications created the complete linear lesions to terminate maccroreentry ATs. Sustained AF was induced by BAP after PVI in 27 patients of SLA group (70.2±9.2 years, 32.9±31.2 months). These patients underwent posterior wall isolation (PWI) and CTI ablation. Unmappable AT was induced by BAP after PVI in 4 patients (Non-SLA group, 6.1%, 67.0±9.7 years, 84.5±105.6 months). These patients underwent PWI, CTI and mitral isthmus ablation on an empirical basis instead of SLA. Using a 90-day blanking period, the single-procedure Kaplan-Meier estimates of AT or AF event-free survival were 79% at 12 months. During follow-up (14.5±8.0 months), although 19 /21 (90.5%) of Non-inducible group patients and 33/41 (80.5%) of SLA group patients did not experience AT or AF recurrence, all of Non-SLA group patients experienced AF recurrence. There was no difference between Non-inducible group and SLA group in predicting recurrence of AT or AF (p=0.3). However, there was a difference when compared with Non-SLA group (each p&lt;0.001). Non-SLA group was an independent powerful predictor resulting in recurrence of AF after adjusting for potential confounding factors (adjusted hazard ratio = 7.17; 95% confidence interval; 2.2–23.1, p=0.001, Wald χ2=10.9). Furthermore, in Kaplan-Meier survival curves for predicting AT or AF recurrence, Non-SLA group was the significant predictive marker of AT or AF recurrence (Log-Lank χ2=18.0, p&lt;0.001). Kaplan-Meier survival curves Conclusions In LSPAF patients without inducibility of any tachycardia after PVI, sinus rhythm was highly maintained without stepwise ablation other than CTI ablation. SLA reduced recurrence of AF in LSPAF patients with AT and AF induced after PVI. In addition, nonselective liner ablations for unmappable AT after PVI were less effective in LSPAF patients.

Achieving durable mitral isthmus block: Challenges, pitfalls, and methods of assessment.

Macroreentrant atrial tachycardias often occur following atrial fibrillation ablation, most commonly due to nontransmural lesions in prior ablation lines. Perimitral atrial flutter is one such arrhythmia which requires ablation of the mitral isthmus. Our objectives were to review the literature regarding ablation of the mitral isthmus and to provide our approach for assessment of mitral isthmus block. We review anatomical considerations, ablation strategies, and assessment of conduction block across the mitral isthmus, which is subject to several pitfalls. Activation sequence and spatial differential pacing techniques are discussed for assessment of both endocardial and epicardial bidirectional mitral isthmus block. Traditional methods for verifying mitral isthmus block include spatial differential pacing, activation mapping, and identification of double potentials. Up to 70% of cases require additional ablation in the coronary sinus (CS) to achieve transmural block. Interpretation of transmural block is subject to six pitfalls involving pacing output, differentiation of endocardial left atrial recordings from epicardial CS recordings, identification of a slowly conducting gap in the line, and catheter positioning during spatial differential pacing. Interpretation of unipolar electrograms can identify nontransmural lesions. We employ a combined epicardial and endocardial assessment of mitral isthmus block, which involves using a CS catheter for epicardial recording and a duodecapolar Halo catheter positioned around the mitral annulus for endocardial recording. The assessment of transmural mitral isthmus block can be challenging. Placement of an endocardial mapping catheter around the mitral annulus can provide a precise assessment of conduction across the mitral isthmus.

Impact of Technique and Technology on Mitral Isthmus Ablation

Mitral isthmus ablation is an established strategy in the treatment of peri-mitral atrial flutter and as an adjunct to pulmonary vein isolation. The objective of this review is to summarize the techniques and specific strategies that allow for increased success and durability of mitral isthmus ablation. Achieving bidirectional block across the mitral isthmus remains a challenge due to the increased thickness in this region, convective cooling as a result of coronary sinus blood flow, and the occurrence of epicardial connections. Several strategies to achieve durable mitral isthmus block, such as coronary sinus ablation, coronary sinus balloon occlusion, ethanol ablation via the vein of Marshall, and using alternate mitral lines in select cases, are described in detail in this review.