Acute impact of the vein of marshall ethanol infusion on newly-formed lesion and mitral line block in persistent atrial fibrillation ablation
Authors: Nesti M , Rossi A , Panchetti L , Startari U , Mirizzi G , Garibaldi S , Formichi B A , Procolo M , Nassi S , Solinas P , Ceccarelli F , Levantesi B , Maionchi A , Piacenti M 
Published: November 2023

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.