Long‐term efficacy and safety of adjunctive ethanol infusion into the vein of Marshall during catheter ablation for nonparoxysmal atrial fibrillation

Vein of Marshall Ethanol Infusion for AF Ablation; A Review

The outcomes of persistent atrial fibrillation (AF) ablation are modest with various adjunctive strategies beyond pulmonary vein isolation (PVI) yielding largely disappointing results in randomised controlled trials. Linear ablation is a commonly employed adjunct strategy but is limited by difficulty in achieving durable bidirectional block, particularly at the mitral isthmus. Epicardial connections play a role in AF initiation and perpetuation. The ligament of Marshall has been implicated as a source of AF triggers and is known to harbour sympathetic and parasympathetic nerve fibres that contribute to AF perpetuation. Ethanol infusion into the Vein of Marshall, a remnant of the superior vena cava and key component of the ligament of Marshall, may eliminate these AF triggers and can facilitate the ease of obtaining durable mitral isthmus block. While early trials have demonstrated the potential of Vein of Marshall 'ethanolisation' to reduce arrhythmia recurrence after persistent AF ablation, further randomised trials are needed to fully determine the potential long-term outcome benefits afforded by this technique.

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

BACKGROUND

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.

HYPOTHESIS

Adjunctive vein of Marshall ethanol injection (VOM-EI) strategies are more effective than conventional catheter ablation (CA) and have similar safety outcomes.

METHODS

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 30 seconds after a 3-month blanking period. Weighted pooled risk ratios (RRs) and corresponding 95% confidence intervals (CIs) were calculated using a random effects model.

RESULTS

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.

CONCLUSION

Our meta-analysis revealed that adjunctive VOM-EI strategies are more effective than conventional CA and have similar safety outcomes.

Comparison of Long-Term Clinical Outcomes Between Segmental and Circumferential Pulmonary Vein Isolation in Patients Undergoing Repeat Atrial Fibrillation Ablation

BACKGROUND

Circumferential pulmonary vein isolation (CPVI) has supplanted segmental PVI (SPVI) as standard procedure for atrial fibrillation (AF). However, there is limited evidence examining the efficacy of these strategies in redo ablations. In this study, we investigated the difference in recurrence rates between SPVI and CPVI in redo ablations for PV reconnection.Methods and Results: This study retrospectively enrolled 543 patients who had undergone AF ablation between 2015 and 2017. Among them, 167 patients (30.8%, including 128 male patients and 100 patients with paroxysmal AF) underwent redo ablation for recurrent AF. Excluding 26 patients without PV reconnection, 141 patients [90 patients of SPVI (Group 1) and 51 patients of CPVI (Group 2)] were included. The AF-free survival rates were 53.3% and 56.9% in Group 1 and Group 2, respectively (P=0.700). The atrial flutter (AFL)-free survival rates were 90% and 100% in Group 1 and Group 2, respectively (P=0.036). The ablation time was similar between groups, and there no major complications were observed.

CONCLUSIONS

For redo AF ablation procedures, SPVI and CPVI showed similar outcomes, except for a higher AFL recurrence rate for SPVI after long-term follow-up (>2 years). This may be due to a higher probability of residual PV gaps causing reentrant AFL.

Impact of Vein of Marshall Ethanol Infusion Combined with Anatomical Ablation for the Treatment of Persistent Atrial Fibrillation: A Long-Term Follow-Up Based on Implantable Loop Recorders

BACKGROUND

The best ablation treatment for persistent atrial fibrillation (PeAF) patients is still debated. The vein of Marshall (VOM) seems to be a promising target for ablation and could be combined with a linear set of ablation lesions. The aim of our study is to evaluate the incidence of AF recurrences in a PeAF population treated with a comprehensive ablation approach consisting of VOM ethanol infusion (EI), pulmonary vein isolation (PVI), a left atrial (LA) roofline, a mitral line (guided by the newly formed lesion after alcohol infusion into the VOM and validated by pacing), and a cavotricuspid isthmus line.

METHODS

Consecutive patients undergoing the first ablation procedure of catheter ablation (CA) for PeAF were enrolled. All patients underwent VOM-EI, PVI, and ablation lines along the roof of the LA, mitral, and cavotricuspid isthmus. LA voltage mapping before and after VOM-EI was also performed. An implantable loop recorder (ILR) was implanted at the end of the ablation in each patient.

RESULTS

Thirty-one consecutive patients (66 ± 8 years and 71% male) affected by PeAF were included in this study. The VOM-EI procedural phase lasted 21.4 ± 10.1 min. PV isolation and lines were validated in all subjects. The ML block was achieved within 10.8 ± 8.7 min. At a mean follow-up of 12 ± 7 months, 27 out of 31 (87%) patients remained free from AT/AF recurrences. Among the patients with recurrences, two (50%) had incomplete ablation lesions and three (75%) had "suboptimal" VOM-EI. In 23/31 patients (74%), antiarrhythmic drugs (AADs) were discontinued after 1 month of follow-up. No significant complications were reported during the follow-up.

CONCLUSIONS

this single-center experience demonstrates that VOM-EI systematically combined with an anatomical ablation set in patients with PeAF resulted in feasible, safe, and effective freedom from AF/AT recurrences in 87% of the population after a 1-year follow-up period according to an ILR.

Angiographic assessment of vein of Marshall in atrial fibrillation: Implications for identification and cannulation

Background

The vein of Marshall (VOM) ethanol infusion improves rhythm control in atrial fibrillation (AF). The identification and cannulation of the VOM can be technically challenging. This study aimed to assess the angiographic morphology of the VOM and investigate its value in the VOM ethanol infusion.

Methods

Patients with AF (n = 162) scheduled for combined catheter ablation and VOM ethanol infusion were enrolled. The VOM morphologic features in the right anterior oblique (RAO), the left anterior oblique (LAO), and the LAO cranial views were analyzed. The impact of morphology on the identification and cannulation of the VOM was investigated.

Results

The VOM was identified in 159 (98.1 %) and cannulated in 150 (92.6 %) patients. The VOM identification rate in the RAO and LAO/LAO cranial view was 97.3 % and 89.3 %, respectively. Of 134 patients with VOM identification in the LAO/LAO cranial view, 104 (77.6 %) had a VOM ostium clock location (VOMoClock) of ≤3 and 3-4 o'clock. The VOM cannulation success rate in the ≤3, 3-4, 4-5, and 5-6 o'clock groups was 100 %, 92.6 %, 88.5 %, and 77.8 %, respectively (p = 0.032). The median (interquartile range) cannulation time in the four groups was 10.5 (6.3), 12.0 (9.0), 13.0 (23.0), and 34.0 (30.0) minutes, respectively (p < 0.001). The diameter of the coronary sinus ostium in the RAO view and the VOMoClock were independent predictors for difficult cannulation.

Conclusions

The VOM morphologic features in different angiographic views provide valuable information which could facilitate the identification and cannulation of the VOM.

The impact of empirical Marshall vein ethanol infusion as a first-choice intraoperative strategy on the long-term outcomes in patients with persistent atrial fibrillation undergoing mitral isthmus ablation

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 seldom been investigated. Here, we aim to compare the efficacy, safety, and long-term outcomes between provisional and empirical MVEI in PeAF patients undergoing the index MI ablation procedure.

Methods

We enrolled 133 patients with PeAF either in the provisional group (n = 38, MVEI was performed when conventional endocardial and/or epicardial ablation procedures were inadequate to achieve bidirectional MI block) or in the empirical group (n = 95, MVEI was performed empirically before MI CA).

Results

All of the baseline characteristics were comparable. Less spontaneous or inducible atrial tachycardias (ATs) were encountered in the empirical group of patients (P < 0.001). More epicardial ablations were applied (26.3% vs. 9.5%, P = 0.016) and a higher incidence of CA-facilitated restoration of sinus rhythm was recorded (86.8% vs. 11.7%, P < 0.001) in the provisional group of patients. 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 (455.9 ± 192.2 vs. 366.5 ± 161.3 s, P = 0.038) was consumed to achieve bidirectional MI block during endocardial ablation in the provisional group. Incidences of procedure-related complications were similar between the two groups. During a 16.5 ± 4.4-month follow-up, the empirical group of patients showed a significantly higher rate of freedom from AT recurrence (95.8% vs. 81.6%, log-rank P = 0.003), while the rate of freedom from AF or atrial tachyarrhythmias (combining AF and AT) was 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 who underwent the index MI ablation procedure, empirical MVEI could reduce endocardial MI ablation time and provide greater long-term freedom from AT recurrence.

A novel stepwise approach incorporating ethanol infusion in the vein of Marshall for the ablation of persistent atrial fibrillation

Introduction

Apart from pulmonary vein isolation (PVI), several step-by-step procedures that aim to modify left atrial substrate have been proposed for the ablation of persistent atrial fibrillation (AF), yet the optimal strategy remains elusive. There are cumulative data suggesting an incremental benefit of adding vein of Marshall (VOM) ethanol infusion to PVI in patients with persistent AF. We sought to evaluate the feasibility and efficacy of a novel stepwise ablation approach, incorporating a VOM alcoholization step, for persistent AF.

Methods

In this single-center study, we prospectively enrolled 66 consecutive patients with symptomatic persistent AF and failure of at least one antiarrhythmic drug (ADD). The ablation procedure consisted of (i) PVI, (ii) left atrial segmentation with VOM ethanol infusion and the deployment of linear radiofrequency lesions across the roof and the mitral isthmus and (iii) electrogram-based ablation of dispersion zones. The first two steps were performed in all patients, whereas the third step was carried out only in those still in AF at the end of the second step. Atrial tachycardias during the procedure were mapped and ablated. At the end of the procedure, cavotricuspid isthmus ablation was additionally performed in all patients. The primary endpoint was 12-month freedom from AF and atrial tachycardia after a single procedure and an initial three-month blanking period.

Results

Total procedure time was 153 ± 38.5 min. Fluoroscopy time was 16 ± 6.5 min and the radiofrequency ablation time was 26.14 ± 0.26 min. The primary endpoint occurred in 54 patients (82%). At 12 months, 65% of patients were off any AAD. In the univariate Cox regression analysis, left ventricular ejection fraction < 40% was the only predictor of arrhythmia recurrence (HR 3.56; 95% CI, 1.04-12.19; p = 0.04). One patient developed a pericardial tamponade and another a minor groin hematoma.

Conclusion

A novel stepwise approach, including a step of ethanol infusion in the VOM, is feasible, safe and provides a high rate of sinus rhythm maintenance at 12 months in patients with persistent AF.

Role of non-pulmonary vein triggers in persistent atrial fibrillation

Pulmonary vein isolation is an well-established treatment strategy for atrial fibrillation (AF), and it is especially effective for patients with paroxysmal AF. However, the success rate is limited for patients with persistent AF, because non-pulmonary vein triggers which increase AF recurrence are frequently found in these patients. The major non-pulmonary vein triggers are from the left atrial posterior wall, left atrial appendage, ligament of Marshall, coronary sinus, superior vena cava, and crista terminalis, but other atrial sites can also generate AF triggers. All these sites have been known to contain atrial myocytes with potential arrhythmogenic electrical activity. The prevalence and clinical characteristics of these non-pulmonary vein triggers are well studied; however, the clinical outcome of catheter ablation for persistent AF is still unclear. Here, we reviewed the current ablation strategies for persistent AF and the clinical implications of major non-pulmonary vein triggers.

Impact of technical aspects of vein of Marshall ethanol infusion on mitral isthmus block for persistent atrial fibrillation ablation

Aims

Ethanol infusion into the VOM (EIVOM) adjunctive to radiofrequency catheter ablation (RFCA) was a novel approach facilitating mitral isthmus (MIth) block for persistent atrial fibrillation (PeAF); However, there were remarkable disparities in its technical aspects. This study aimed to evaluate the impact of EIVOM technical aspects on acute MIth block.

Methods

Eighty consecutive patients (63 males, average age 66.4 ± 8.6 years) undergoing de novo PeAF ablation were assigned to different groups. The procedural parameters in “EIVOM first” (n = 13) or “RFCA first” (n = 13) as well as small dose ([SD], ≤4 ml, n = 26) or big dose ([BD], >4 ml, n = 54) approaches were analyzed to identify the predictors for acute MIth block.

Results

Compared with the “EIVOM first” approach, the “RFCA first” approach was associated with longer procedural and MIth ablation time (134 ± 27 min vs. 112 ± 17 min; 14.9 ± 5.5 min vs. 9.3 ± 5.1 min, both P < 0.05, respectively), but with comparable success of MIth block. The ethanol dose was 6.3 ± 1.5 ml in BD group vs. 3.1 ± 1.0 ml in SD group (P < 0.001) and was correlated significantly with the size of Δlow voltage area (r = 0.66, P < 0.001). The success of MIth block was 92.6% in BD group vs. 73.1% in SD group, P = 0.03. The ethanol dose >5.75 ml independently predicted successful MIth block (OR: 0.428, 95% CI: 0.219–0.839, P = 0.01).

Conclusions

Despite the comparable effectiveness on MIth block, the “EIVOM first” approach was associated with shorter procedural and MIth ablation time than the “RFCA first” approach. The ethanol dose in EIVOM was an independent predictor for MIth block.

Ethanol Infusion of Vein of Marshall for the Treatment of Persistent Atrial Fibrillation: The Basics and Clinical Practice

Catheter ablation for persistent atrial fibrillation (PeAF) is particularly challenging, as the clinical outcomes are modest. Pulmonary vein isolation (PVI) plus linear ablation is one of the main strategies for PeAF ablation. Completely durable transmural lesions are difficult to achieve by catheter ablation during mitral isthmus ablation. The ligament of Marshall contains the vein of Marshall (VOM), myocardial tracts and innervation, and serves as arrhythmogenic foci that make it an attractive target in catheter ablation of atrial fibrillation. Additionally, it co-localizes with the mitral isthmus, and may serve as a part of the perimitral isthmus reentrant circuit. Ethanol infusion into the VOM results in rapid ablation of the neighboring myocardium and its innervation. Its incorporation into PVI significantly increases the success rate of mitral isthmus block and the clinical outcome of PeAF ablation.

The Long-Term Outcomes of Ablation With Vein of Marshall Ethanol Infusion vs. Ablation Alone in Patients With Atrial Fibrillation: A Meta-Analysis

Background

The long-term outcomes of ablation with vein of Marshall ethanol infusion (VOM-ABL) compared with ablation alone in patients with atrial fibrillation (AF) remains elusive. We aimed to explore whether VOM-ABL showed better long-term benefits and screen the potential determinants of outcome impact of VOM-ABL procedure.

Methods

PubMed, Cochrane Library, Web of Science, and Embase were searched up to 1st September 2021. Studies comparing the long-term (one-year or longer) outcomes between VOM-ABL and ablation alone were included. Subgroup analysis identified potential determinants for VOM-ABL procedure.

Results

Compared with ablation alone, VOM-ABL was associated with a significantly higher rate of long-term freedom from AF/AT (risk ratio [RR], 1.28; 95% confidence interval [CI], 1.12–1.47; p = 0.00) and successful mitral isthmus (MI) block (RR, 1.52; 95% CI, 1.16–1.99; p = 0.00), whereas, there was no significant difference in pericardial effusion, stroke/transient ischemic attack (TIA), and all-cause death. Subgroup analysis identified two significant treatment-covariate interactions: one was ablation strategy subgroup (pulmonary vein isolation plus linear and/or substrate ablation [PVI+]; RR, 1.41; 95% CI, 1.27–1.56 vs. PVI; RR, 1.05; 95% CI, 0.92–1.19, p = 0.00 for interaction) for freedom from AF/AT, while the other was VOM-ABL group sample size subgroup (≥ 100; RR, 1.98; 95% CI, 1.24–3.17 vs. <100; RR, 1.20; 95% CI, 1.10–1.30, p = 0.04 for interaction) for MI block.

Conclusions

This meta-analysis demonstrates that VOM-ABL has superior efficacy and comparable safety over ablation alone in AF patients with long-term follow-up. Moreover, PVI+ and VOM-ABL group sample size ≥ 100 may be associated with a great impact on freedom from AF/AT and MI block, respectively.

Innovations in atrial fibrillation ablation

BACKGROUND

Catheter-based ablation to perform pulmonary vein isolation (PVI) has established itself as a mainstay in the rhythm control strategy of atrial fibrillation. This review article aims to provide an overview of recent advances in atrial fibrillation ablation technology.

METHODS

We reviewed the available literature and clinical trials of innovations in atrial fibrillation ablation technologies including ablation catheter designs, alternative energy sources, esophageal protection methods, electroanatomical mapping, and novel ablation targets.

RESULTS

Innovative radiofrequency (RF) catheter designs maximize energy delivery while avoiding overheating associated with conventional catheters. Single-shot balloon catheters in the form of cryoballoons, radiofrequency, and laser balloons have proven effective at producing pulmonary vein isolation and improving procedural efficiency and reproducibility. Pulsed field ablation (PFA) is a highly anticipated novel nonthermal energy source under development, which demonstrates selective ablation of the myocardium, producing durable lesions while also minimizing collateral damage. Innovative devices for esophageal protection including esophageal deviation and cooling devices have been developed to reduce esophageal complications. Improved electroanatomical mapping systems are being developed to help identify additional non-pulmonary triggers, which may benefit from ablation, especially with persistent atrial fibrillation. Lastly, the vein of Marshall alcohol ablation has been recently studied as an adjunct therapy for improving outcomes with catheter ablation for persistent atrial fibrillation.

CONCLUSIONS

Numerous advances have been made in the field of atrial fibrillation ablation in the past decade. While further long-term data is still needed for these novel technologies, they show potential to improve procedural efficacy and safety.

Adjunctive Vein of Marshall Ethanol Infusion During Atrial Fibrillation Ablation: A Systematic Review and Meta-Analysis

Introduction

Catheter ablation (CA) for atrial fibrillation (AF) can be associated with limited efficacy. Due to its autonomic innervation, the vein of Marshall (VOM) is an attractive target during AF ablation. In this meta-analysis, we aimed to evaluate the efficacy and safety of adjunctive ethanol infusion of VOM (VOM-EI) in AF ablation.

Methods

We performed a comprehensive literature search for studies that evaluated the efficacy and safety of VOM-EI in AF ablation compared to AF catheter ablation alone. The primary outcome of interest was late (≥3 months) AF or atrial tachycardia (AT) recurrence. The secondary outcomes included acute mitral isthmus bidirectional block (MIBB) and procedural complications (pericardial effusion, stroke, or atrio-esophageal fistula). Pooled relative risk (RR) and corresponding 95% confidence intervals (CIs) were calculated using the random-effects model.

Results

A total of four studies, including 804 AF patients (68.2% with persistent AF, the mean age of 63.5±9.9 years, 401 patients underwent VOM-EI plus CA vs. 403 patients who had CA alone), were included in the final analysis. VOM-EI group was associated with a lower risk of late AF/AT recurrence (RR:0.63; 95% CI:0.46-0.87; P = 0.005), and increased probability to achieve acute MIBB (RR:1.39; 95% CI:1.08-1.79; P = 0.009) without an increase in procedural complications (RR:1.05; 95% CI:0.57-1.94; P = 0.87).

Conclusions

Our meta-analysis demonstrated that adjunctive VOM-EI strategy is more effective than conventional catheter ablation with similar safety profiles.

Durability of Left Atrial Lesions After Ethanol Infusion in the Vein of Marshall

OBJECTIVES

The aim of this study was to assess the persistence of left atrial (LA) lesions created by ethanol infusion in the vein of Marshall (EIVM) by electroanatomical mapping on repeat catheter ablation for recurrent atrial tachyarrhythmia.

BACKGROUND

Little is known about the durability of LA lesions created by EIVM.

METHODS

The study included consecutive patients who underwent EIVM for persistent atrial fibrillation or perimitral LA flutter (index procedure) and repeat catheter ablation for recurrent atrial tachyarrhythmia or atrial fibrillation at a single center between January 2019 and April 2020. The acute effect of EIVM was assessed at the index procedure by comparing the area of bipolar voltage <0.05 mV in the vein of Marshall (VOM) region before and immediately after EIVM. The long-term effect of EIVM was assessed by comparing this area in the VOM region between the redo procedure and the index procedure.

RESULTS

Twenty-four consecutive patients (mean age 68.6 ± 6.1 years, 58% men) underwent redo procedures after previous EIVM for persistent atrial fibrillation (n = 21 [88%]) or perimitral LA flutter (n = 5 [21%]). In each patient, the EIVM-related lesion persisted, with a chronic scar in the VOM region (median 13.1 cm² [interquartile range: 8.1-15.9 cm²] vs 12.4 cm² [interquartile range: 7.6-15.7 cm²] acutely, respectively). One quarter of patients (9 of 20) had late mitral isthmus reconnection, which was located at the mitral annular edge or in the coronary sinus.

CONCLUSIONS

Atrial lesions created by EIVM are durable, which reinforces the efficacy profile of EIVM. Reconduction sites in the mitral isthmus are located at the edge of the scar and in the coronary sinus.

Durability of mitral isthmus ablation with and without ethanol infusion in the vein of Marshall

INTRODUCTION

Ethanol infusion in the vein of Marshall (EIVOM) effectively creates a linear ablation lesion in the mitral isthmus (MI). However, data on the long-term success rates of MI ablation is limited.

METHODS AND RESULTS

Our cohort consisted of 560 patients with nonparoxysmal atrial fibrillation (AF) who underwent an initial MI ablation. Ablations were performed by only radiofrequency (RF) in 384 (RF group) or by RF and EIVOM in 176 (EIVOM/RF group) patients; 5 ml anhydrous ethanol was used to perform EIVOM in advance of RF. Following EIVOM, RF pulses were delivered to the lateral MI line. Bidirectional MI block was fully achieved in 353/384 (92%) (First 318, Re-do 35) patinents in the RF group and 171/176 (97%) (First 128, Re-do 43) patients in the EIVOM/RF group (p = .09 in the first, p = .10 in the re-do ablation cases). In cases with complete MI line block, recurrent AF or atrial tachycardia was observed in 130/353 (37%) patients in the RF group and in 64/171 (37%) patients in the EIVOM/RF group (log-rank p = .12 in the first, and p = .30 in the re-do ablation cases). Of the total 560 patients, 123 proceeded to the subsequent ablation session. Reconduction across MI line block was observed in 39/80 (49%) patients in the RF group and 25/43 (58%) patients in the EIVOM/RF group (p = .32).

CONCLUSION

EIVOM effectively ensures MI line block; however, the reconduction rate was similar between the two groups.

Feasibility, efficacy, and safety of ethanol infusion into the vein of Marshall for atrial fibrillation: A meta-analysis

BACKGROUND

Contemporary radiofrequency catheter ablation (RFCA) approaches for atrial fibrillation (AF) have reached an efficacy "ceiling". Ethanol infusion into the vein of Marshall (EI-VOM) has shown potential in preliminary studies. Data on EI-VOM are largely limited to small single-center reports, and clinical benefits and risks have not been systematically examined. Therefore, we performed a meta-analysis to assess the feasibility, efficacy, and safety of EI-VOM for AF.

METHODS

All studies evaluating EI-VOM for AF were initially searched from four electronic search engines: PubMed, Web of Science, Cochrane Library, and SinoMed. We used RevMan5.4 to calculate pooled outcomes of randomized controlled trial and cohort studies. We also performed single-arm meta-analyses using Open Meta-Analyst.

RESULTS

We included a total of 10 studies with 1322 patients. Successful EI-VOM was performed in 86.7% (95% CI 81.9-91.4%) of patients. For persistent AF patients, the recurrence of AF and/or atrial tachycardia (AT) was significantly lower in the EI-VOM combined with RFCA group compared with RFCA alone group (RR 0.58, 95% CI 0.35 to 0.96, p = 0.04). EI-VOM combined with RFCA significantly increased the rate of bidirectional mitral isthmus block compared with RFCA alone in AF patients (RR 1.50, 95% CI 1.34 to 1.67, p < 0.001). There were nine cardiac tamponades observed in 644 patients (PR 0.8%, 95% CI 0.1-1.5%) who were performed EI-VOM combined with RFCA.

CONCLUSIONS

Our meta-analysis brings encouraging evidence that adjuvant EI-VOM reduces AF and/or AT recurrence rate in persistent AF patients and increases the success rate of bidirectional mitral isthmus block.

Efficacy and safety of ethanol infusion into the vein of Marshall for mitral isthmus ablation

INTRODUCTION

Chemical ablation by retrograde infusion of ethanol into the vein of Marshall (VOM-EI) can facilitate the achievement of mitral isthmus block. This study sought to describe the efficacy and safety of this technique.

METHODS AND RESULTS

Twenty-two consecutive patients (14 males, median age 71 years) with attempted VOM-EI for mitral isthmus ablation were included in the study. VOM-EI was successfully performed with a median of 4 ml of 96% ethanol in 19 patients (86%) and the mitral isthmus was successfully blocked in all (100%). Touch up endocardial and/or epicardial ablation after VOM-EI was necessary for 12 patients (63%). Perimitral flutter was present in 12 patients (63%) during VOM-EI and terminated or slowed by VOM-EI in 4 and 3 patients, respectively. The low-voltage area of the mitral isthmus region increased from 3.1 cm² (interquartile range [IQR] 0-7.9) before to 13.2 cm² (IQR: 8.2-15.0) after VOM-EI and correlated significantly with the volume of ethanol injected (p = .03). Median high-sensitive cardiac troponin-T increased significantly from 330 ng/L (IQR: 221-516) the evening of the procedure to 598 ng/L (IQR: 382-769; p = .02) the following morning. A small pericardial effusion occurred in three patients (16%), mild pericarditis in one (5%), and uneventful VOM dissection in two (11%). After a median follow-up of 3.5 months (IQR: 3.0-11.0), 10 of 18 patients (56%) with VOM-EI and available follow-up had arrhythmia recurrence. Repeat ablation was performed in five patients (50%) and peri-mitral flutter diagnosed in three (60%).

CONCLUSION

VOM-EI is feasible, safe, and effective to achieve acute mitral isthmus block.

Vein of Marshall ethanol infusion in the treatment of atrial fibrillation: From concept to clinical practice

The vein of Marshall (VOM) contains innervation, myocardial connections, and arrhythmogenic foci that make it an attractive target in catheter ablation of atrial fibrillation (AF). Additionally, it co-localizes with the mitral isthmus, which is critical to sustain perimitral flutter, and is a true atrial vein that communicates with underlying myocardium. Retrograde balloon cannulation of the VOM from the coronary sinus is feasible and allows for ethanol delivery, which results in rapid ablation of neighboring myocardium and its innervation. Here we review the body of work performed over a span of 13 years, from the inception of the technique, to its preclinical validation, to demonstration of its ablative and denervation effects, and finally to completion of a randomized clinical trial demonstrating favorable outcomes, improving rhythm control in catheter ablation of persistent AF.

Atrial Fibrillation Ablation Using Vein of Marshall Ethanol Infusion

Catheter ablation has become a cornerstone treatment for atrial fibrillation (AF). Pulmonary vein isolation is the accepted approach for paroxysmal AF ablation, but it is less effective for persistent AF. The vein of Marshall (VOM) is located in the epicardial left atrium and can be a source of AF triggers as well as a tract for autonomic nerves. It directly communicates with the underlying myocardium, including the left atrial ridge and the posterior mitral isthmus. This review discusses the latest evidence regarding the mechanisms, procedural aspects, and outcomes of VOM ethanol infusion when used as an adjunct to pulmonary vein isolation in patients with persistent AF.

Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation (Marshall-PLAN): Prospective, single-center study

BACKGROUND

Beyond pulmonary vein isolation (PVI), the optimal ablation strategy for persistent atrial fibrillation (AF) remains poorly defined.

OBJECTIVE

The purpose of this study was to examine a novel comprehensive ablation strategy (Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation [Marshall-PLAN]) strictly based on anatomical considerations.

METHODS

Left atrial (LA) sites were sequentially targeted as follows: (1) coronary sinus and vein of Marshall (CS-VOM) musculature; (2) PVI; and (3) anatomical isthmuses (mitral, roof, and cavotricuspid isthmus [CTI]). The primary endpoint was 12-month freedom from AF/atrial tachycardia (AT).

RESULTS

Seventy-five consecutive patients were included (age 61 ± 9 years; 10 women; AF duration 9 ± 11 months; mean LA volume 197 ± 43 mL). VOM ethanol infusion was completed in 69 patients (92%). The full Marshall-PLAN lesion set (VOM, PVI, mitral, roof, and CTI with block) was successfully completed in 68 patients (91%). At 12 months, 54 of 75 patients (72%) were free from AF/AT after a single procedure (no antiarrhythmic drugs) in the overall cohort. In the subset of patients with a complete Marshall-PLAN lesion set (n = 68), the single procedure success rate was 79%. After 1 or 2 procedures, 67 of 75 patients (89%) remained free from AF/AT (no antiarrhythmic drugs). After 1 or 2 procedures, VOM ethanol infusion was complete in 72 of 75 patients (96%).

CONCLUSION

A novel ablation strategy that systematically targets anatomical atrial structures (VOM ethanol infusion, PVI, and prespecified linear lesions) is feasible, safe, and associated with a high rate of freedom from arrhythmia recurrence at 12 months in patients with persistent AF.

The ligament of Marshall and arrhythmias: A review

The ligament of Marshall (LOM) is a remnant of the embryonic sinus venosus and left cardinal vein, and contains fat and fibrous tissues, blood vessels, muscle bundles, nerve fibers, and ganglia. The complexity of LOM's structure makes it as a source of triggers and drivers as well as substrates of re-entry for atrial arrhythmias, especially for atrial fibrillation (AF). LOM also serves as a portion of left atrial macro-re-entrant circuit, especially peri-mitral isthmus re-entrant circuit. Experimental studies demonstrate that the LOM acts as a sympathetic conduit between the left stellate ganglion and the ventricles, and participates in the initiation and maintenance of ventricular arrhythmias. Endocardial or epicardial catheter ablation or ethanol infusion into the vein of Marshall may serve as an important adjunct therapy to pulmonary vein isolation in patients with advanced stage of AF, and may help alleviate ventricular arrhythmias as well.

Acute and mid-term outcome of ethanol infusion of vein of Marshall for the treatment of perimitral flutter

Aims 

We hypothesized that an epicardial approach using ethanol infusion in the vein of Marshall (EIVOM) may improve the result of ablation for perimitral flutter (PMF).

Methods and results 

We studied 103 consecutive patients with PMF undergoing high-resolution mapping. The first 71 were treated with radiofrequency (RF) ablation alone (RF-group), and the next 32 underwent EIVOM followed by RF on the endocardial and epicardial mitral isthmus (EIVOM/RF-group). Contact force was not measured during ablation. Acute and 1-year outcomes were compared. Flutter termination rates were similar between the RF-group (63/71, 88.7%) and EIVOM/RF-group (31/32, 96.8%, P = 0.27). Atrial tachycardia (AT) terminated with EIVOM alone in 22/32 (68.6%) in the EIVOM/RF-group. Bidirectional block of mitral isthmus was always achieved in the EIVOM/RF-group, but significantly less frequently achieved in the RF-group (62/71, 87.3%; P = 0.05). Median RF duration for AT termination/conversion was shorter [0 (0–6) s in the EIVOM/RF-group than 312 (55–610) s in the RF-group, P &lt; 0.0001], as well as for mitral isthmus block in the EIVOM/RF-group [246 (0–663) s] than in the RF-group [900 (525–1310) s, P &lt; 0.0001]. Pericardial effusion was observed in 1/32 (3.2%) in EIVOM/RF-group and 5/71 (7.0%) in RF-group (P = 0.66); two in RF-group required drainage and one of them developed subsequent ischaemic stroke. One-year follow-up demonstrated fewer recurrences in the EIVOM/RF-group [6/32 (18.8%)] than in the RF-group [29/71 (40.8%), P = 0.04]. By multivariate analysis, only EIVOM was significantly associated with less AT recurrence (hazard ratio = 0.35, P = 0.018).

Conclusion 

Ethanol infusion in the vein of Marshall may reduce RF duration required for PMF termination as well as for mitral isthmus block without severe complications, and the mid-term outcome may be improved by this approach.

Ablation of Incessant Premature Ventricular Complex Through Retrograde Transvenous Ethanol Infusion

Ethanol infusion has been used for the treatment of ventricular arrhythmia. We describe a case of ethanol infusion through the coronary sinus venous network to treat refractory epicardial premature ventricular complexes. The premature ventricular complexes were initially successfully suppressed but recurred after resolution of the myocardial edema. (Level of Difficulty: Intermediate.).