Background Ethanol infusion in the vein of Marshall (EIVM) has shown to be effective for treating atrial fibrillation (AF) and perimitral left atrial (LA) flutter (PMLAF). Aims To assess the persistence of LA lesions created by EIVM by electro-anatomical mapping (EAM) at repeated procedure for recurrent atrial tachycardia (AT) or AF. Methods We included consecutive patients who underwent EIVM then repeated CA for recurrent AT or AF with high-definition EAM in a single center. Acute and long term EIVM effect was assessed at the index and redo procedures by comparing the area of bipolar voltage <0.05 mV in the vein of Marshall (VOM) region before, immediately after and late after EIVM. Results 24 consecutive patients (mean age 68.6±6.1 years, 58% men) underwent redo procedure after previous successful EIVM for persistent AF (n=21; 88%) or PMLAF (n=5; 21%). In each case, EIVM had an acute effect, with a post-EIVM scar in the VOM (median 12.4 cm2 [interquartile range (IQR) 7.6–15.7]). Mitral isthmus (MI) bidirectional block was obtained in 20/24 patients (83%). In each patient, the EIVM-related lesion persisted, with a chronic scar in the VOM region (median 13.1 cm2 [IQR 8.1–15.9]). One quarter of patients (5/20) had late MI reconnection, which was located at the mitral annulus 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 MI are located at the edge of the mitral annulus and in the coronary sinus.