Background: It is established that ethanol infusion in the vein of Marshall (EIVOM) effectively creates a linear ablation lesion in the mitral isthmus (MI). However, data on the long-term success rates of MI ablation remains limited. Methods and Results: Our cohort consisted of 560 patients with non-paroxysmal atrial fibrillation (AF) who underwent an initial MI ablation. Ablations were performed by only radiofrequency (RF) in 384 patients (RF group) or by RF and EIVOM in 176 patients (EIVOM/RF group). Ethanol of 5 mL was used to perform EIVOM in advance of RF. Following EIVOM, RF pulses were delivered to the lateral MI line. Bidirectional MI block was fully achieved in 353 (first 318, re-do 35) patients of the RF group and 171 (first 128, re-do 43) patients of the EIVOM/RF group (p = 0.09 in the first, 0.10 in the re-do ablation cases). In cases with complete MI line block, recurrent AF or atrial tachycardia (AT) was observed in 130 (37%) patients of the RF group and in 64 (37%) patients of the EIVOM/RF group (log-rank p = 0.12 in the first, 0.30 in the re-do ablation cases). Of the total 194 patients, 112 with drug refractory AF or AT proceeded to the subsequent ablation process. Reconnection of MI block line was observed in 39 (49%) patients in the RF group and 25 (58%) patients in the EIVOM/RF group (p = 0.32). Conclusion: EIVOM effectively ensures MI line block; however, the reconnection rate was similar between the two groups.

Introduction: The isolation of superior vena cava (SVCI) and pulmonary vein isolation (PVI) improve the success rate of atrial fibrillation (AF) ablation. Limited information is available on the quantitative assessment of the narrowing of SVC after ablation. Methods: Ninety-one AF patients with SVC potentials were enrolled in this study. After PVI, SVCI was performed circumferentially at the level of the lower border of the right pulmonary artery. Radiofrequency (RF) pulses were delivered on a point-by-point basis for 30s at each point with an irrigated catheter in a temperature-controlled mode with the maximum temperature set at 42℃ and the maximum power at 25W. Follow up contrast-enhanced computed tomography was performed at four months after the ablation procedure. SVC narrowing was followed up in time (mean ± standard deviation = 20 ± 4.2 months). Results: All SVCIs were successfully achieved without severe complications. The pre-ablation SVC dimension at the level of the isolation line was 2.50 ± 0.94 cm2, and the post-ablation SVC dimension was 2.19 ± 0.82 cm2 (p = 0.016). Severe stenosis (reductions of SVC dimension > 75%) was not observed in this study. Moreover, the relationship between the SVC narrowing and the RF application time was not significant in this study. In the eight SVC cases with SVC narrowing, the mean SVC area recovered as a function time from 1.56 ± 0.42 cm2 to 1.80 ± 0.57cm2. Conclusion: The SVCI caused minor reductions in the SVC dimensions, but did not cause severe stenosis with life-threatening symptoms.