Perimitral atrial tachycardias dependent on residual nonligament of Marshall conduction

Abstract

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

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

“…This could partially explain why in our study, the AF-free success rate did not show statistical improvement after the implementation of the empirical MVEI strategy (78.9% vs. 7 6.3%, log-rank P = 0.334). However, ultrahigh-resolution mapping and entrainment pacing along the MA demonstrated that about two-thirds of the perimitral ATs were MV-dependent ( 28 ). Addition of MVEI to CA could reduce the incidence of AT recurrence when patients underwent empirical ethanol infusion (95.8% vs. 81.6%, log-rank P = 0.003).…”

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

“…PMAT is an inhomogeneous diagnosis including those involving only the endocardial aspect of MI, VOM-dependent, and those utilizing non-MB epicardial connections. 25 In our study, we did not specifically classify the PMAT into these groups since high-density mapping was not routinely used, and as the local electrogram in VOM was absent, we were unable to directly verify the involvement of an epicardial connection and record the effect of EIVOM. In the future, techniques that can facilitate detailed activation mapping, including the activation of epicardial structures, should be developed.…”