Mitral Isthmus Ablation Research Articles

Evaluation of posterior mitral isthmus ablation in the absence of a vein of Marshall.

Achieving acute and durable mitral isthmus (MI) block remains challenging using radio frequency (RF)-catheter ablation alone. Vein of Marshall (VoM) ethanolisation results in chemical damage along the mitral isthmus resulting in the creation of a durable transmural lesion with a very high rate of procedural block. However, no studies have systematically assessed the efficacy of MI ablation alone when no anatomical VoM is present. Thirty seven patients without VoM evidenced after careful angiographic examination were included. Ablation parameters and result were compared to a matched control group in whom the posterior MI line was performed without assessing the presence of the VoM. MI block was achieved in 36 out of 37 patients without VoM (97%), with endocardial ablation only in 5/37 (14%) and combined endocardial and CS ablation in 32/37 patients (86%). There was a significant difference in occurrence of block between patients without a VoM and the control group (97,3% vs. 65% respectively, p<0,01), with a trend towards less needed RF (26 (IQR 20-38) vs 29 (IQR 19-40) tags (p=0.8), 611 (IQR 443-805) vs 746 (IQR 484-1193) seconds (p=0.08)). The absence of a Vein of Marshall is associated with a very high rate of procedural block during posterior mitral isthmus ablation. The higher rate of MI block in this specific population would also suggest the crucial role of the Vein of Marshall (when present) in resistant MI block.

Mechanisms of Mitral Isthmus Reconnection After Ablation With and Without Vein of Marshall Ethanol Infusion.

Reconnection of the mitral isthmus (MI) is common after radiofrequency ablation (RFA). Vein of Marshall ethanol infusion (VOMEI) expedites MI ablation, but long-term results are unclear. This study sought to determine anatomic substrates of failed MI ablation, with and without VOMEI. Consecutive VOMEI procedures were included (n=231; of which 140 were de novo ablations and 91 were prior RFA failures (rescue VOMEI). MI conduction mechanisms were studied with vein of Marshall (VOM) electrograms obtained with a 2-F octapolar catheter, mapping, and differential pacing. In rescue VOMEI, intact VOM electrograms showed epicardial connections, epi-endocardial dissociation, and VOM conduction in pseudo-MI block. After VOMEI, after a follow-up of 725 ± 455days, 78 patients (33.7%) experienced recurrence. Of those, 36 (46%) had evidence of MI reconnection and 42 had other mechanisms. Of the 36 patients with MI reconnection, endocardial radiofrequency (RF) at the annular MI restored block in 16 (45%), and coronary sinus (CS) RF was required in 20 (55%). Post-VOMEI recurrence mechanisms included CS connection-dependent arrhythmias: CS-mediated perimitral flutter, CS-to-left atrium (LA) and CS ostial re-entry, and CS focal activity. Intraprocedural factors associated with MI reconnection included volume of ethanol delivered≥4mL (OR: 0.74; P=NS), CS ablation at VOMEI (OR: 4.05; P=0.003), and age (OR: 1.06; P=0.011). MI reconnections after RFA are due to epicardial connections from VOM. Recurrences after VOMEI are due to incomplete annular MI RFA and CS arrhythmogenesis including CS-mediated perimitral flutter, CS-to-LA re-entry and CS focal activity. Adding complete CS disconnection to VOMEI may prevent recurrences.

Risk assessment of esophageal ulceration following left atrial radiofrequency linear ablation.

Esophageal safety following radiofrequency (RF) left atrial (LA) linear ablation has not been established. To determine the esophageal safety profile of LA linear RF lesions, we performed systematic esophagogastroduodenoscopy in all patients with intraesophageal temperature rise (ITR) ≥ 38.5°C. Between December 2021 and July 2023, a total of 200 consecutive patients with atrial tachyarrhythmia (ATA) underwent linear ablation with posterior dome (roof or floor) or posterior mitral isthmus line transection. Patients with ITR ≥ 38.5°C were scheduled for esophageal endoscopy ~3 weeks after ablation. Patient and ATA characteristics, procedural parameters, endoscopy findings and ablation lesion data were collected and analyzed. One hundred thirty-threeout of 200 (67%) patients showed ITR ≥ 38.5°C during LA linear ablation. ITR (with maximal temperature of 45.7°C) was more frequently observed during floor line ablation (82% of cases). ITR was less observed during roof line ablation (34%) and posterior mitral isthmus ablation (4%). Endoscopy, performed in 115 patients after 24 ± 10 days, showed esophageal ulceration in four patients (two patientsKansas City classification [KCC] 2a and two patients KCC 2b). No patient showed esophageal perforation or fistula. Temperature rise during LA linear ablation is frequent and ulceration risk exists, particularly when floor line is performed. Safety measures are needed to avoid potential severe complications like esophageal perforation and fistula.

In Silico TRials guide optimal stratification of ATrIal FIbrillation patients to Catheter Ablation and pharmacological medicaTION: the i-STRATIFICATION study.

Patients with persistent atrial fibrillation (AF) experience 50% recurrence despite pulmonary vein isolation (PVI), and no consensus is established for secondary treatments. The aim of our i-STRATIFICATION study is to provide evidence for stratifying patients with AF recurrence after PVI to optimal pharmacological and ablation therapies, through in silico trials. A cohort of 800 virtual patients, with variability in atrial anatomy, electrophysiology, and tissue structure (low-voltage areas, LVAs), was developed and validated against clinical data from ionic currents to electrocardiogram. Virtual patients presenting AF post-PVI underwent 12 secondary treatments. Sustained AF developed in 522 virtual patients after PVI. Second ablation procedures involving left atrial ablation alone showed 55% efficacy, only succeeding in the small right atria (<60 mL). When additional cavo-tricuspid isthmus ablation was considered, Marshall-PLAN sufficed (66% efficacy) for the small left atria (<90 mL). For the bigger left atria, a more aggressive ablation approach was required, such as anterior mitral line (75% efficacy) or posterior wall isolation plus mitral isthmus ablation (77% efficacy). Virtual patients with LVAs greatly benefited from LVA ablation in the left and right atria (100% efficacy). Conversely, in the absence of LVAs, synergistic ablation and pharmacotherapy could terminate AF. In the absence of ablation, the patient's ionic current substrate modulated the response to antiarrhythmic drugs, being the inward currents critical for optimal stratification to amiodarone or vernakalant. In silico trials identify optimal strategies for AF treatment based on virtual patient characteristics, evidencing the power of human modelling and simulation as a clinical assisting tool.

Preliminary real-world experience on mitral isthmus ablation with a novel catheter that toggles between radiofrequency and pulsed field ablation

Abstract Background The mitral isthmus (MI) is frequently targeted during the ablation of persistent atrial fibrillation (AF). Nevertheless, achieving a complete bidirectional MI block using radiofrequency (RF) is often technically challenging and time-consuming1,2. Previously, we described a fluoroscopy-guided technique to achieve MI block using a penta-spline pulsed field ablation (PFA) catheter3. Recently, a new catheter was introduced, which toggles between RF and PFA and is integrated into a 3D mapping system, thus supposedly facilitating its use for the ablation of extra-pulmonary vein structures4. Purpose To describe the acute efficacy and procedural features of the first cases of posterior MI ablation performed with the toggling catheter at two centers. Methods We collected and reviewed demographic, clinical and procedural features of all patients who underwent ablation of the posterior MI at our centers between September and October 2023. Ablation of the MI was performed with either RF or PFA according to operator’s discretion. Bidirectional MI block was validated through activation mapping and differential pacing. Results During the study period, 44 patients were treated with the toggling catheter. Out of them, 16 patients (aged 68.3±10.1 years; 29% females) underwent posterior MI ablation for persistent AF, in addition to PVI and posterior wall isolation. Mean history of AF was 29.8±34.5 months and mean LA volume 135.6±54.9 ml. Skin-to-skin procedural time (93 minutes, IQR 64-112), LA mapping time (9.0 min, IQR 7.3-12.1) and time required for MI ablation (4.0 min, IQR 3.3-6.5) were remarkably short. In PFA-treated patients (10 cases), first-pass MI block was achieved in 8 (80%), with 16 (IQR 12-22) applications; none of these patients required RF touch-up. In the remaining 6 RF-treated patients, first-pass MI block was achieved in 3 (50%) patients with 8 (IQR 6-13) applications. Additional PFA applications (median 3, IQR 2-5) on the most venous portion of the MI were required in all RF-treated patients. In the 5 patients in whom bidirectional block could not be achieved at first-pass, remapping and touch-up application time were 2.6 (IQR 2.6- 6.3) and 2.0 (IQR 0.8-5.2) minutes, respectively. Eventually, bidirectional MI block was achieved in 16/16 (100%) patients by the end of the procedure. Importantly, no patients in the entire cohort experienced complications such as coronary artery spasm or clinically significant pericardial effusion. Conclusions Several observations can be made on this first real-world experience on posterior MI ablation with the toggling catheter: first, acute safety and efficacy in achieving a bidirectional MI block are high with both PFA and RF; secondly, patients undergoing RF ablation often require additional PFA applications on the venous segment of the MI; lastly, the time required to achieve MI block is remarkably short even when remapping and touch-up applications are needed.Figure 1Figure 2

Feasibility and procedural safety of the pentaspline pulsed field ablation catheter for atrial lesions beyond pulmonary vein isolation

Abstract Background The pentaspline multi-electrode pulsed-field ablation (PFA) catheter is widely used for the ablation of atrial fibrillation (AF). Given the favorable safety profile of PFA, lesions beyond pulmonary vein isolation (PVI) are increasingly performed. Purpose We aimed to assess the feasibility and safety of PFA beyond PVI with the pentaspline PFA catheter. Methods We retrospectively studied all patients who underwent PFA for atrial arrhythmias in our center between January and October 2023. Procedural characteristics and complications were compared between patients undergoing only PVI (PVI-only group) and those receiving extra-venous applications (extra-PVI group). Results We analysed 202 PFA cases. Indications for ablation included paroxysmal AF (34.7%), persistent AF (57.4%), long-standing persistent AF (5.9%) and atypical atrial flutter (2%). Redo procedures accounted for 18.8% of the total cases. PFA beyond PVI was performed in 142 (70.3%) patients. Patients in the extra-PVI group had a higher incidence of persistent AF (76.8% vs 11.7%, p&amp;lt;0.001), a higher BMI (29±5 vs 26±5 kg/m2, p=0.001) and a more dilated left atrium (LAVI: 73±24 vs 52±20 ml/m2, p&amp;lt;0.001, Table 1). PFA in this group consisted of PVI (98.6%), posterior wall isolation (PWI) (93%), mitral isthmus (MI) ablation (56.3%), a roof line (2.1%), ablation of dispersion electrograms (10.6%) and cavotricuspid isthmus (CTI) ablation (0.7%). In 22 (15.5%) patients, additional CTI ablation with radiofrequency (RF) was performed, while alcohol ablation of the vein of Marshall and RF ablation in the coronary sinus were required in 9 (6.3%) and 2 (1.4%) patients, respectively, to achieve MI block. Compared to the PVI-only group, PFA beyond PVI required a mean of 43 additional applications, a longer procedural (84±29 vs 65±22 min, p&amp;lt;0.001) and fluoroscopy time (25±10 vs 18±6 min, p&amp;lt;0.001) and had a higher fluoroscopy dose (24±35 vs 16.4±28.5 Gy.cm2, p=0.001). A three-dimensional electroanatomic map was used in 12% of cases. Acute success rates were 99% for PVI and PWI, 89% for MI ablation and 100% for roof lines and CTI ablation. Overall complication rates were similar in both groups (16.2% vs 13.3%, p=0.68, Table 2). One cardiac tamponade was observed in the extra-PVI group (0.7%) compared to 4 in the PVI-only group (6.7%, p=0.03). Among the latter, 2 incidents occurred during PVI in patients with long-standing persistent AF, precluding further extra-venous ablation. A small pericardial effusion (without hemodynamic compromise) and/or pericarditis were seen in 9.2% of patients in the extra-PVI group compared to 6.7% in the PVI-only group (p=0.78). No deaths occurred in either group. Conclusions Ablation beyond PVI with the pentaspline PFA catheter is feasible with high success rates and no apparent increase in procedural complications. However, it increases procedural duration and fluoroscopy. Notably, the majority of cardiac tamponades in this cohort occurred during PVI.

Comparison of pulsed field and radiofrequency ablation for non-paroxysmal atrial fibrillation: a propensity score-matched analysis

Abstract Background Ablation of non-paroxysmal atrial fibrillation (AF) is challenging and often requires left atrial substrate ablation. While the pentaspline, multi-electrode pulsed-field ablation (PFA) catheter is approved for pulmonary vein isolation (PVI), its role in procedures involving substrate ablation for nonparoxysmal forms of AF remains unknown. Purpose We conducted a retrospective study to assess the safety and long-term outcomes of PFA for non-paroxysmal AF. Methods Procedural and follow-up data were retrospectively collected for all patients undergoing a first-time ablation for non-paroxysmal AF across two centers, between November 2021 and December 2022. Patients undergoing PFA consisting of PVI, isolation of the posterior wall (PWI) and ablation of the mitral isthmus (MI) with the pentaspline multi-electrode PFA catheter, were compared with patients undergoing radiofrequency ablation (RFA) involving PVI, a roof line or PWI, alcohol ablation of the vein of Marshal (VOM) and MI ablation. Patients were matched using propensity scores to minimize potential confounders. The primary endpoint was arrhythmia (AF/atrial flutter/atrial tachycardia) recurrence after a 90-day blanking period. Results The baseline characteristics of the 116 matched patients are detailed in Table 1. PVI was successful in all patients. In the PFA group, PWI was additionally performed in all patients and MI ablation in 83% of cases, resulting in acute success rates of 97% and 96%, respectively. In the RFA group lesions beyond PVI included: a roof line (90%), PWI (10%), VOM alcohol ablation (93%) and MI ablation with ablation in the coronary sinus (CS) if needed (97%). Procedural block across the roof and the MI was achieved in 96% and 95%, respectively and complete PWI in 83% of cases. The PFA group had a shorter total procedure (84.2±22.3 vs 117.3±24.8 min, p&amp;lt;0.001) but a longer fluoroscopy time (23.1±7.2 vs 16.8±6.3 min, p&amp;lt;0.001). The difference in radiation dose, however, was not statistically significant (57.7±74.1 Gy.cm2 in the PFA vs 49.8±53.6 Gy.cm2 in the RFA group, p=0.24). The overall periprocedural complication rates were similar in both groups (8.6% PFA vs 12.1% RFA, p=0.76), with no cardiac tamponades or deaths. Group-specific complications included 1 coronary spasm in the PFA group and 1 CS dissection in the RFA group. During a median follow-up of 447 days (IQR: 364-552), 1 stroke occurred in each group and 1 sudden cardiac death in the RFA group, 13 months post-procedure. Both groups had similar rates of recurrences (32.8% PFA vs 25.9% RFA, p=0.54). Arrhythmia-free survival probability at 16 months was estimated at 67.2% for PFA and 77.6% for RFA by Kaplan-Meier analysis (p=0.16, Figure 1). Conclusions In this propensity-matched cohort of patients with non-paroxysmal AF, PFA and RFA demonstrated similar complication rates and arrhythmia-free survival at follow-up. The procedure duration, however, was significantly shorter with PFA.Figure 1

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.

Pulmonary vein isolation with additional substrate ablation for atrial fibrillation results in an increased risk for the development of atypical atrial flutter

Abstract Introduction Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) catheter ablation. Several extra pulmonary vein (PV) ablation strategies for substrate modification (PVI plus) have been employed to AF patients. It has not been proven that this approach decreases the recurrence of AF, and it could contribute to increase the risk of developing atypical atrial flutter. Methods Patients submitted to AF catheter ablation at our centre between 2005 and 2020 were included. Using logistic regression, we did a retrospective analysis of the association between the application of PVI plus strategies (such as ablation of the cavo tricuspid isthmus (CTI), ganglion plexus, isolation of the superior vena cava (SVC), mitral isthmus ablation and atrial roof line ablation) and the development of atypical flutter later submitted to ablation. Results Five hundred and seventy-five patients were included (64% males, age 57±12 years [between 14 and 81], 68.2% with paroxysmal AF) with &amp;gt; 1-year follow-up. Five hundred and five (87.8%) had PVI alone. From the 575 patients, 11 (1.9%) developed an atypical flutter during the follow-up, which was later submitted to ablation. The crude ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 13.92 times higher than the one of those submitted to a stand-alone PVI technique, with a p value &amp;lt;0.001 (95% CI 3.96 – 48.87). When adjusted for age and history of heart failure, the ODDS of a patient submitted to a PVI plus strategy developing atypical atrial flutter are 16.29 times higher than the one of those submitted to a stand-alone PVI technique, with a p value &amp;lt;0.001 (95% CI 3.92 – 67.65). Conclusions Additional substrate ablation for AF significantly increases the risk of developing atypical auricular flutter.Characteristics of the study populationCharacterization of PIV plus strategies

Low voltage area in the left atrial anterior wall predict Marshall-PLAN failure in patients with persistent atrial fibrillation

Abstract Background The most appropriate ablation strategy for persistent atrial fibrillation (PeAF) has not yet been determined. However, ethanol infusion of the vein of Marshall (VOM) combined with a linear set of ablation lesions (namely the Marshall-PLAN) has yielded encouraging results (1). Purpose Our study aimed at analyzing the relationship between low voltage areas (LVA) and arrhythmias recurrences in a PsAF population treated with the Marshall-PLAN. Methods we conducted a retrospective study on consecutive patients undergoing first catheter ablation (CA) for PsAF between 2021 and 2022 at our center. Pulmonary vein isolation (PVI), mitral isthmus ablation (VOM ethanol infusion, endocardial ablation and epicardial ablation in the great cardiac vein), left atrial (LA) roofline and cavo-tricuspid isthmus ablation were carried out in all the patients. Bidirectional block was validated for all the linear lesions as well as for PVI. Pre-ablation LA electroanatomic maps were built with CARTOv3 system and the PentaRay mapping catheter (minimum 3000 points). LVA were identified as areas &amp;gt;1cm2 (containing ≥3 neighboring points with ≤10mm distance) with bipolar voltage &amp;lt;0.5mV in SR and &amp;lt;0.24 mV in AF (2). All patients were followed for at least 12 months. Results Overall, 93 patients (69±7years, 30% female) with PsAF were included. Their left-ventricle ejection fraction and left atrial volume indexed for body surface area (LAVI) were 57% and 92±20 ml/m2. LA maps demonstrated at least one LVA in 70 subjects (75.3%). The mean relative surface of LA in which a LVA was evidenced was 8±14%. LVA were found within the anterior LA wall in 49 patients (53%), in the posterior wall in 33 patients (35.5%), in the inferior wall in 22 patients (24%), in the lateral wall in 14 patients (15.1%) and in the pulmonary vein region in 44 patients (47.3%). After 19±6 months of follow-up, 28 (30%) patients had AF recurrence. At Cox regression analysis (including LVA burden and LAVI dimensions), LVA localized within the anterior LA wall were predictive of arrhythmia recurrences (hazard ratio [HR] 2.0 [95% CI, 1.1–4.7], P=0.04). Kaplan-Meier estimates of survival free from recurrences at 20 months were 51% and 88% in patients with and without LVAs in the anterior LA wall (Log-rank 0.006). Conclusions The Marshall-PLAN led to a global AF-free survival of 70% after 19±6 months in our cohort of patients with PsAF. Importantly however, the data show that the subset of patients with LVA in the anterior LA wall (i.e., the LA region not targeted by the pre-specified ablation set here evaluated) have a 55%-only AF-free survival while that of patients without LVA in the anterior LA wall was of 88%. As a result, our study supports the relevance of atrial substrate assessment and the possibility of CA strategy optimization in the subset of patients with PsAF and LVA in the anterior LA wall (3).

Acute hemodynamic effects of the Marshall-Plan ablation on left and right atrial pressure: does 'respecting atrial physiology' prevent stiff left atria? A retrospective single- center analysis

Abstract Introduction Stiff left atrium (STILA)-syndrome is a relevant concern after extensive ablation in the left atrium (LA) e.g. in persistent atrial fibrillation (AF). STILA often causes disabling heart failure symptoms worse than the initial arrhythmia symptoms. Therefore preventing adverse ablation-induced hemodynamic effects is of utmost concern. Methods This single-center study retrospectively analyzed data from 89 consecutive patients who underwent biatrial ablation for AF following the Marshall-Plan between February 2022 and November 2023. The procedures included ablation of the CTI and PVI where necessary followed by ablation of a LA roof line and ablation of the lateral mitral isthmus after previously performed ethanol ablation of the vein of Marshall. This lesion set is considered to maintain physiological activation of the LA. This study evaluates acute hemodynamic changes following the Marshall-Plan. Invasive hemodynamic measurements of mean left and right atrial pressure, as well as A- and V-waves were performed in all patients before and after the ablation. We assessed the acute changes of atrial hemodynamics in these procedures. Continuous data are given as mean ± standard deviation, categorical data are expressed as number and percentages. Differences between groups were determined by Student’s t-test, chisquare-test, and Fisher’s exact test using SPSS software. A p-value of &amp;lt;0.05 was deemed significant. Results The patients' mean age was 70.1 ± 7.5 years and 39.0% were female. Mean BMI was 28.9 ± 5.2 kg/m². Procedures were performed under general anesthesia (with a PEEP of 5.5cmH2O (2-10 cmH2O)) and took 181 minutes on average. Left atrial mean pressure averaged at 15.7mmHg before the procedure. The overall average change of left atrial mean pressure was +1,8mmHg. The average change in left atrial A- and V-Wave amounted to -1.9mmHg and -0.9mmHg respectively. The pre-procedural average right atrial mean pressure was 12.1mmHg. Right atrial mean pressure inclined by +1.6mmHg. The average change in right atrial A- and V-Wave was +0.6mmHg and +1.1mmHg respectively. The i.v. administered volume averaged 1900 ± 285ml. 3.3% of patients showed an increase of mean LA-pressure &amp;gt;9mmHg. Those patients tended to be older (74.3years), were all male (100%) and had a higher BMI (31.5 kg/m²) as well as higher amount of i.v. administered volume (2333ml) and a longer procedure (213min). Discussion Complex and extensive biatrial ablation following the Marshall-Plan does not lead to acute significant increases in left or right atrial pressures. The administered i.v. volume might explain the slight increases observed. In our observation, the rate of significant increases in LA-pressure is low. This suggests that disrupting the (left) atrial activation pattern might play a role in the development of diastolic dysfunction and thereby STILA-syndrome. Respecting atrial physiology may be beneficial for preventing adverse hemodyamic changes after ablation.

Vein of Marshall ethanol infusion related lesion durability. A randomized dual centre pilot study

Abstract Introduction Vein of Marshall ethanol infusion (VOM-EI) creates a local ablation which includes epicardial bridges, AF triggers, vein innervation and facilitates mitral isthmus (MI) ablation. Recent trials demonstrated that in persistent AF patients the addition of VOM-EI to RF catheter ablation (CA) increased success rate vs CA alone. Moreover, a novel CA strategy (VOM-EI, PVI, and specific linear lesions set) is associated with a high rate of freedom from AF. Nevertheless, in these studies VOM-EI and RFCA were performed as different step of the same procedure. We hypothesize that performing electro-anatomical mapping (EAM) right after the VOM-EI would lead to an overestimation of ethanol-induced scar because of a certain amount of reversible oedema. This could affect the durability of the lesion set and possibly the success rate. Aim We postulated that VOM-EI performed at least 1 month earlier than RFCA would show a significantly smaller EAM low voltage area as compared to the standard strategy. Methods Patients with recurrent persistent AF with no history of previous ablation were enrolled in this randomized, dual centre, pilot study. All included patients were randomized 1:1 to group 1 (experimental): VOM-EI and after at least one month later high-definition (HD)-EAM and RFCA (PVI, MI, LA dome, cavo-tricuspid isthmus). group 2 (control): to a standard procedure (VOM-EI then 5 minute later HD-EAM and RFCA). Primary endpoint was ethanol induced HD-EAM scar area. According to the endpoint patients with unsuccessful VOM-EI were excluded. Moreover patiets with or no branches morphology, VOM dissection, and mechanical leakage were also excluded because these are demonstrated to be related to a smaller VOM-EI related lesion. Clinical and procedure related data were also collected. Results Forty consecutive patients met the inclusion criteria. The two groups did not differ for baseline characteristics (see table 1). Mean ethanol-induced HD-EAM scar area was significantly smaller in 20 patients where VOM-EI was performed at least 1 month earlier as compared to the standard procedure group (2,5±2,4 vs 11,2±9,5 cm2, p=0,018). The set of linear lesions was successful achieved in all patients. Notably the two group did not differ for any procedural technical aspect of mitral isthmus block (table 1). Neither VOM-EI nor AF ablation procedure related complications were recorded. Conclusion This is the fist randomized pilot study to demonstrate that a consistent amount of ethanol-induced related lesion could be reversible at least in its endocardial aspect of the left atrium. This would possibly affect the long-term stability of the lesion set. Notably, we still had a high rate of block at first mitral line attempt which could possibly be related to a persistent effect of VEOM-EI on the epicardial aspect of the left atrium. Larger population, randomized trial is needed to confirm this preliminary result and if it would affect the procedure success.Table 1Picture 1

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.

Impact of Posterior Wall Isolation During AF Ablation on the Incidence of Left Atrial Flutter

BackgroundLinear and complex electrogram ablation (LCEA) beyond pulmonary vein isolation (PVI) is associated with an increase in left atrial macro–re-entrant tachycardias (LAMTs). Posterior wall isolation (PWI) is increasingly performed to improve AF ablation outcomes. However, the impact of PWI on the incidence of LAMT is unknown. ObjectivesThe purpose of this study was to establish the incidence of LAMT following PVI alone vs PVI + PWI vs PVI + PWI + LCEA. MethodsConsecutive patients undergoing catheter ablation for AF or LAMT post-AF ablation between 2008 and 2022 from 4 electrophysiology centers were reviewed with a minimum follow-up of 12 months. ResultsIn total, 5,619 (4,419 index, 1,100 redo) AF ablation procedures were performed in 4,783 patients (mean age 60.9 ± 10.6 years, 70.7% men). Over a mean follow-up of 6.4 ± 3.8 years, 246 procedures for LAMT were performed in 214 patients at a mean of 2.6 ± 0.6 years post-AF ablation. Perimitral (52.8% of patients), roof-dependent (27.1%), PV gap-related (17.3%), and anterior circuits (8.9%) were most common, with 16.4% demonstrating multiple circuits. The incidence of LAMT was significantly higher following PVI + PWI (6.2%) vs PVI alone (3.0%; P < 0.0001) and following PVI + PWI + LCEA vs PVI + PWI (12.5%; P = 0.019). Conduction gaps in previous ablation lines were responsible for LAMT in 28.4% post-PVI alone, 35.3% post-PVI + PWI (P = 0.386), and 81.8% post-PVI + PWI + LCEA (P < 0.005). ConclusionsThe incidence of LAMT following PVI + PWI is higher than with PVI alone but significantly lower than with more extensive atrial substrate modification. Given a low frequency of LAMT following PWI, empiric mitral isthmus ablation is not justified and may be proarrhythmic.

Differential Pacing Maneuver From the Vein of Marshall.

Bidirectional mitral isthmus (MI) block is conventionally verified by differential pacing from the coronary sinus (CS) and its sequence change. This study aimed to evaluate the ability of differential pacing from the vein of Marshall (VOM) to detect epicardial MI connections. Radiofrequency and VOM ethanol MI ablation were performed with a VOM electrode catheter inserted to the septal side of the ablation line. MI block was verified using conventional CS pacing. To perform differential VOM pacing analysis, initial pacing was delivered from a distal VOM bipole closer to the block line, and then from a proximal VOM bipole. The intervals from pacing stimulus during different VOM pacing sites to the electrogram recorded through the CS catheter on the opposite side of the line were compared. When the interval during distal VOM pacing was longer than that during proximal VOM pacing, it indicated a VOM connection block; however, if the former interval was shorter, the connection through the VOM was considered persistent. Overall, 50 patients were evaluated. According to CS pacing, MI ablation was incomplete in 9 patients, in whom the analysis indicated persistent VOM connection. Among 41 patients with complete MI block, confirmed by CS finding, in 30 (73%) patients, the interval during distal VOM pacing was longer than that during proximal VOM pacing by 11±5 ms. However, in 11 patients (27%) the former interval was revealed to be shorter than the latter by 16±8 ms, indicating residual VOM connection. Conduction time across the line was significantly shorter in 11 patients than in the other 30 (166±21 versus 197±36 ms; P<0.01). Ten successful reevaluated analyses after VOM ethanol and further radiofrequency ablation of the connection indicated VOM block achievement. Differential VOM pacing maneuver reflects the VOM conduction status. This maneuver can uncover residual epicardial connections that are missing with CS pacing.

Clinical effect of vein of Marshall ethanol infusion on mitral isthmus ablation.

This study aimed to investigate the effect of Marshall ethanol infusion (VOM-Et) in the vein on mitral isthmus (MI) ablation. Patients with persistent atrial fibrillation (AF) were grouped into vein of VOM-Et combined with radiofrequency (RF) ablation (VOM-Et-RF) and RF groups. The primary outcome was MI block immediate block rate after surgery. Stratified analysis was also performed for factors affecting the outcome measures. A total of 118 consecutive patients underwent AF ablation at Taizhou Hospital of Zhejiang Province from January 2018 to December 2021. Successful bidirectional perimitral block was achieved in 96% of patients in VOM-Et-RF (69 of 72) and in 76% of patients in the RF group (35 of 46) (P < 0.01). In the subgroup analysis, male sex, elder than 60 years, Left atrial diameter <55 mm, and AF duration <3 years were associated with the benefits of VOM-Et in AF Patients. The vein of Marshall ethanol infusion for catheter ablation can improve the MI block rate. Male sex, elder age, smaller Left atrial diameter and shorter AF duration may have significant benefits for VOM-Et.

The effect of an initial catheter ablation with an adjunctive ethanol infusion into the vein of Marshall on persistent atrial fibrillation.

Some previous studies have reported that a first-step ethanol infusion into the vein of Marshall (EIVOM) with touch-up radiofrequency (RF) ablation can facilitate mitral isthmus (MI) block and improves the ablation outcomes in persistent atrial fibrillation (PeAF) patients. However, the effect of an initial RF ablation with an adjunctive EIVOM has not been fully investigated. This study enrolled 233 PeAF patients undergoing pulmonary vein isolation and linear ablation including an MI, roof line, and cavotricuspid isthmus ablation. An EIVOM was performed when endocardial ablation with or without coronary sinus ablation failed to create MI block. Bidirectional MI block was achieved in 224 patients (96.1%). Among them, MI block was obtained by only RF ablation in 174/224 patients (77.7%) (RF group) and an adjunctive EIVOM was needed in 50/224 (22.3%) (EIVOM group). During the follow-up, 113 (64.9%) RF group patients were free from AF/atrial tachycardia compared to 41 (82.0%) EIVOM group patients (log-rank p = .045). In a multivariate Cox regression analysis, an adjunctive EIVOM was associated with a lower recurrence rate (hazard ratio = 0.39, 95% confidence interval = 0.17-0.78, p = .006). An initial RF ablation with an adjunctive EIVOM strategy improved MI ablation's acute success rate and was associated with better clinical outcomes.

Empirical Marshall vein ethanol infusion as the first-line strategy in patients with persistent atrial fibrillation undergoing mitral isthmus ablation

Abstract Background Marshall vein ethanol infusion (MVEI) as an additional therapy to conventional catheter ablation (CA) has been proved to be efficacious in patients with persistent atrial fibrillation (PeAF). However, whether empirical MVEI could be the first-line strategy in mitral isthmus (MI) ablation has seldomly been investigated. Objective To compare the efficacy, safety and long-term outcomes between provisional and empirical MVEI in PeAF patients undergoing their index MI ablation. Methods We enrolled 133 propensity-score matched patients with PeAF at a ratio of 1:2.5 either into the provisional group (n=38, MVEI was performed when conventional endocardial and/or epicardial ablations were inadequate to achieve bidirectional MI block) or the empirical group (n=95, MVEI was applied empirically before MI CA). Baseline characteristics, procedure results and long-term outcomes were compared between groups. Results All of the baseline characteristics were comparable. Less spontaneous or inducible atrial tachycardias (ATs) including MI-dependent ones were encountered in the empirical group (P&amp;lt;0.001). More epicardial ablations were applied (26.3% vs 9.5%, P=0.016) and higher incidence of CA-facilitated restoration of sinus rhythm was recorded (86.8% vs 11.7%, P&amp;lt;0.001) in the provisional group. Although more fluoroscopy time (6.4[4.2, 9.3] vs 9.5[5.9, 11.6] min, P=0.019) and radiation exposure (69.0[25.3, 160.2] vs 122.0[62.5, 234.1] mGy, P=0.010) were documented in the empirical group with comparable procedure time, less time was consumed to achieve bidirectional MI block during endocardial ablation in the empirical group (455.9±192.2 vs 366.5±161.3 sec, P=0.038). Incidences of procedure-related complications were similar between groups. During a 16.5±4.4-month follow-up, the empirical group showed significantly higher freedom from AT recurrence (81.6% vs 95.8%, log-rank P=0.003), while the freedoms from AF recurrence were similar. Both univariate (HR 0.19, 95%CI 0.05-0.64, P=0.008) and multivariate (HR 0.25, 95%CI 0.07-0.92, P=0.037) Cox regression analyses indicated that empirical MVEI was independently associated with lower long-term AT recurrence. Conclusion Among patients with PeAF underwent their index MI ablations, empirical MVEI could reduce the endocardial MI ablation time and improve the long-term freedom from AT recurrence.Flowchart of the study.Freedoms from AF and AT recurrence

Acute impact of the vein of marshall ethanol infusion on newly-formed lesion and mitral line block in persistent atrial fibrillation ablation

Abstract Catheter ablation in persistent atrial fibrillation (PeAF) has limited success. Strategies beyond pulmonary veins isolation failed to demonstrate improvement of long-term rhythm maintenance. The vein of Marshall (VoM) is a promising therapeutic target because it contains triggers and autonomic parasympathetic and sympathetic activity implicated in arrhythmogenesis of AF. Moreover, as the VoM colocalizes with the trajectory of the "mitral isthmus", alcohol infusion into the vein facilitates bidirectional block across the line eliminating protected epicardial connections (1,2). Purpose We evaluated acute impact on lesion formation post-VOM-ETHO and the mitral line block validation after an approach including VOM-ETHO, pulmonary vein isolation (PVI), roof-line, mitral line (ML) and cavo-tricuspid isthmus line in a population of PeAF patients (Figure 1). We aimed also to report procedural outcomes after a short follow-up period. Methods After a detailed electroanatomical map of the left atrium (LA) (filter at 0.05-0.5 mV if the patient was in sinus rhythm or 0.05-0.3 mV in the case of AF), we thus proceeded with the VoM-ETHO using the technique previously described (3,4). LA map was thus repeated to assess the extension of the newly-formed low voltage area (LVA). According to the newly-formed LVAs, mitral isthmus ablation was completed endocardially. PVI, roof-line and cavo-tricuspid isthmus line were performed to complete the ablation setting. Bidirectional block across line was then validated during pacing from left atrial appendage. In case of persistence of conduction through the mitral line due to epicardial gaps, additional ablations were applied in the "anchored wall" or in the "free-wall" of the great cardiac vein (GCV). Results Twenty-one PeAF patients (67±6 years; 67% male) underwent ablation. The medium value of basal LA-LVAs was 3.1±63.8 cmq and the newly-formed LVAs after the VoM-ETHO procedure was 12.35±67.28 cmq. All patients had bidirectional block validated across the roof-line. Bidirectional block of the ML was achieved in 19/21 patients: in 12/21 patients after endocardial line only and in 9/21 after epicardial gaps ablations into the coronary sinus. The ML procedural time was 11.3±65.9 minutes. No major complications occurred. One patient had mild pericardial effusion due to VoM perforation with a spontaneous resolution. After a short follow-up period (6±63 months), no relapse of AF was observed in 19/21 (90%) patients. 12/21 patients were free from antiarrhythmic drugs (AADs). Interestingly, recurrences happened in patients in whom bidirectional block of the mitral line was not achieved. Conclusions VoM ethanol ablation added to PVI and linear lesions in the context of a methodical and anatomical approach seems to have promising results in PeAF patients. This strategy seems to be safe and reproducible. A favourable outcome depended on the interventional setting completion and the procedural end-points validation is crucial.

Comparison of the effect of ethanol infusion into the vein of Marshall between with and without collateral veins.

Despite the potential benefits of ethanol infusion into the vein of Marshall (EIVOM) for atrial fibrillation (AF) ablation, concerns about its reversible and unpredictable effects persist. To assess the effectiveness of EIVOM in the vein of Marshall (VOM) with collateral veins (CVs) during mitral isthmus and AF ablation. We included 142 AF patients. EIVOM was performed before radiofrequency ablation, and low-voltage areas (<0.5 mV) were measured before, immediately after, and 1 h after EIVOM. Among the 142 patients, 93 (65%) underwent EIVOM, and among these, 35 (37%) were found to have CVs. In the VOM with CVs group, areas with low voltage measured 0 (0-1.85) cm2 before EIVOM, 6.9 (4.1-11.2) cm2 immediately after EIVOM, and 5.7 (3.5-10.6) cm2 1 h after EIVOM. Conversely, in the group designated as VOM without CVs-from which the nine leakage cases were excluded-the areas measured 0 (0-1.35) cm2 , 5.5 (2.6-11.8) cm2 , and 4.7 (1.8-13.5) cm2 at the respective time points. MI line block was fully achieved in 89% (31/35) of cases in the VOM with CVs group and 88% (44/49) in the VOM without CVs groups (p = .94). There was no significant difference in the outcome of AF ablation between these groups (log-rank p = .73). Additionally, no significant difference was observed between EIVOM (+) and EIVOM (-) groups (log-rank p = .59). EIVOM effectively creates MI line block, and its beneficial effects are sustained for at least 1 h after the procedure despite the low-voltage areas showing a slight reduction in size.