Ethanol Infusion of Atrial Flutter Mediated by the Vein of Marshall

BACKGROUND: Atypical atrial flutter (AFL) after atrial fibrillation (AF) ablation, particularly when mediated by epicardial structures such as the vein of Marshall (VOM), poses a therapeutic challenge. CASE SUMMARY: A 64-year-old woman presented with recurrent AFL after AF ablation. High-density and entrainment mapping confirmed a macro-re-entrant circuit involving the VOM via epicardial conduction. After failed endocardial ablation, ethanol infusion into the VOM immediately terminated the tachycardia. At 1-year follow-up, the patient maintained sinus rhythm with a marked improvement in left ventricular ejection fraction (from 46% to 68%). DISCUSSION: For postablation AFL, comprehensive mapping is crucial to identify epicardial substrates. VOM-mediated flutter can be effectively treated with ethanol infusion. TAKE-HOME MESSAGE: This case underscores that VOM-mediated epicardial connections can sustain AFL after AF ablation, and targeted ethanol infusion is a highly effective therapeutic strategy.