Ethanol Infusion Into the Vein of Marshall for Atrial Fibrillation: Clinical Efficacy and Technical Limitations

BACKGROUND: Despite advancements in radiofrequency ablation (RFCA) technology and strategy, the long-term rhythm outcomes of persistent atrial fibrillation (PeAF) remain suboptimal. Since the vein of Marshall (VOM) is situated within the mitral isthmus (MI) area and covers local neural innervation and fiber networks, its pathophysiological role in mediating and maintaining atrial fibrillation (AF) and causing arrhythmia recurrence has garnered increasing attention. HYPOTHESIS: Ethanol infusion into the vein of Marshall (EIVOM) may complement RFCA by delivering anatomically targeted chemical injury along the VOM course, thereby facilitating contiguous MI lesion formation and durable MI block. METHODS: We performed a narrative review of mechanistic, procedural, and clinical evidence regarding EIVOM in AF ablation, with emphasis on MI block, rhythm outcomes, technical limitations, complications, and its potential role in pulsed field ablation (PFA)-based workflows. RESULTS: Available evidence indicates that EIVOM facilitates durable MI block by targeting VOM-related epicardial connections and may improve rhythm outcomes when combined with RFCA in selected PeAF ablation strategies. Its clinical application is influenced by procedural and anatomical factors, while safety considerations and its potential complementary role in PFA-based workflows remain important areas for further evaluation. CONCLUSIONS: EIVOM is a promising adjunct to RFCA, particularly for facilitating durable MI block and reducing residual epicardial conduction. Further standardized multicenter studies are needed to refine patient selection, procedural integration, safety optimization, and its role in contemporary AF ablation.