Ethanol Infusion in the Vein of Marshall during Atrial Fibrillation Ablation: A Systematic Review and Meta-Analysis

BACKGROUND Ethanol infusion into the vein of Marshall (EIVOM) is proposed to improve atrial fibrillation (AF) ablation outcomes, though its efficacy is uncertain. This study reviews EIVOM's effect on AF catheter ablation. METHOD Systematic searches in PubMed, Embase, and Scopus identified studies comparing EIVOM with radiofrequency (RF) ablation. A random-effects model pooled mean differences with 95% confidence intervals (CIs), and heterogeneity was assessed with the I2 statistic. R 4.2.3 was used for statistical analyses, including leave-one-out sensitivity analyses and Baujat plots to assess heterogeneity and study influence. RESULTS We included 15 studies (four randomised controlled trials and 11 cohort studies) comprising 3,507 patients (mean age 64.07±9.57 years), of whom 73.25% were men and 1,536 were treated with EIVOM. This technique was associated with improved mitral isthmus (MI) block rates (relative risk [RR] 1.33; 95% CI 1.13-1.57; p<0.001) and reduced AF/atrial tachycardia (AT) recurrence (RR 0.65; 95% CI 0.52-0.80; p<0.001). No significant differences were found in MI reconnections (RR 0.65; 95% CI 0.31-1.34; p=0.240) while fluoroscopy (standardised mean difference [SMD] 0.25; 95% CI -0.86 to 1.37; p=0.656) and procedure times were longer in the EIVOM group (SMD 11.70 minutes; 95% CI -1.67 to 25.16; p=0.088). In the subgroup analyses, ethanol volumes >5 mL enhanced MI block and AF/AT recurrence. CONCLUSION EIVOM and RF are associated with a reduced MI block rates and recurrence of AF and AT when compared with RF only.