A Novel Reversed U Curve Method to Facilitate Ethanol Infusion into the Vein of Marshall in Atrial Fibrillation: A Single-Center Case Series Study

Background: Ethanol infusion into the vein of Marshall (EI-VOM) is widely used to facilitate atrial fibrillation ablation and block of the mitral isthmus. However, it cannot be completed in some anatomically challenging cases. This study aimed to introduce and evaluate a novel reversed U curve method of EI-VOM. Methods: This case-series study enrolled consecutive patients with atrial fibrillation or atrial flutter who were scheduled for EI-VOM. When VOM venography was successfully performed, the conventional EI-VOM method was attempted first. If this approach failed or took ≥20 min, the novel method was applied. The success rate, complications, and applicable anatomical conditions of the new method were summarized. Results: Of the 205 patients enrolled in this study, the novel method was applied to 45 patients, and technical success was achieved in 42 patients (93.3%). Among the patients who underwent the novel method, twenty-four (53.3%) had a long cavotricuspid isthmus, nineteen (42.2%) had a VOM ostium close to the coronary sinus ostium, and sixteen (35.6%) had a prominent Eustachian ridge. The total mean procedure time of EI-VOM using the novel method was 30.00 ± 4.5 min. Acute bidirectional mitral isthmus block was achieved in 40 cases (88.9%), and the mean ethanol volume injected was 8.21 ± 1.5 mL. No serious in-hospital complications were documented in patients treated with the novel method. Conclusions: In this single-center case series, the reversed U curve method appeared feasible as a femoral bailout strategy for EI-VOM in selected anatomically challenging cases. Further prospective, multicenter studies involving multiple operators are required to confirm its reproducibility, efficacy, and safety over conventional approaches.