Double‐Balloon Versus Selective Vein of Marshall Ethanol Infusion for Mitral Isthmus Block in Atrial Fibrillation

BACKGROUND: Achieving durable mitral isthmus (MI) block remains challenging in persistent atrial fibrillation (PeAF). Vein of Marshall ethanol infusion (VOMEI) facilitates MI block, but the impact of ethanol delivery technique on lesion formation and procedural outcomes is not well established. METHODS: In this prospective, single-center study, 106 patients with PeAF were assigned to three groups: RF-only (n = 57), selective VOMEI (n = 34), and double-balloon VOMEI (n = 15). Electroanatomic mapping was performed before and after ethanol infusion. The primary procedural endpoint was acute bidirectional MI block. Secondary endpoints included ethanol volume, scar area, voltage reduction, need for adjunctive radiofrequency (RF) ablation, arrhythmia recurrence, and procedural safety. RESULTS: The primary procedural endpoint, acute bidirectional MI block, was achieved in both VOMEI groups; however, the double-balloon technique delivered significantly higher ethanol volumes and produced larger bipolar and unipolar scar areas with greater voltage reduction compared with selective cannulation (all p < 0.05). It also significantly reduced the need for endocardial and epicardial RF ablation (endocardial RF need: 24.4% vs. 75.6%, p = 0.032; epicardial RF need: 3.4% vs. 96.6%, p < 0.001). Although arrhythmia recurrence rates were lower in the double-balloon group, the differences were not statistically significant (AF recurrence: 0% vs. 8.8% in the selective VOMEI group; p = 0.347). No significant procedural complications were observed. CONCLUSIONS: Double-balloon VOMEI enhances substrate modification and achieves MI block with less adjunctive RF ablation than selective cannulation in PeAF ablation. Optimizing ethanol delivery at the VOM ostium may improve procedural effectiveness. Larger randomized studies are needed to confirm long-term clinical benefits and refine patient selection. CLINICAL TRIAL REGISTRATION: This study was not registered in a clinical trials registry, as it was designed as a prospective single-center observational procedural study rather than an interventional clinical trial.