Linear ablation at the mitral isthmus following mitral valve surgery

Abstract Background Creating a conduction block along the mitral isthmus (MI) can be challenging due to anatomical factors. Ethanol infusion into the vein of Marshall (EIVOM) has proven effective in facilitating this process. Patients with previous mitral valve surgery (MVS) are at high risk of atrial fibrillation (AF) and atrial tachycardia (AT). Feasibility and outcome of EIVOM and MI ablation in MVS patients remain unknown. Objectives This study sought to evaluate the feasibility, safety and durability of EIVOM and MI in MVS patients. Methods A total of 54 consecutive MVS patients undergoing EIVOM and MI ablation were retrospectively included in this study. We evaluated the feasibility and efficacy of EIVOM and MI ablation. Results Mean age was 64±12 years, 46.3% were female and the mean left atrial volume index was 56±18 ml/m². Catheter ablation (CA) was performed within a mean of 12±11 years after MVS. MV surgery was replacement in 74% of patients and annuloplasty in the remaining 26%. Of note, 8% had a concomitant Maze and/or a prior CA for pulmonary vein isolation (PVI). However, only 6 Patients (11.1%) had an attempted mitral isthmus ablation during index surgery. EIVOM was successful with no complications in 92.6% of the patients using 9.5±2.2ml of Ethanol 96% with a mean procedure time of 24±15 minutes. MI conduction block could be achieved in 88.9% with the epicardial ablation via the coronary sinus needed in 94.4% of the patients. A subgroup analysis was conducted to compare outcomes between MV replacement and MV annuloplasty, revealing no significant difference in EIVOM success (95% vs. 85.7%, p=0.58) or rates of acute MI block (90% vs. 86%, p=0.64). An additional subgroup analysis examined MI acute block rates between patients with prior Maze and/or catheter ablation (CA) procedures versus those without, also finding no significant difference (92% vs. 85.2%, p=0.67). Conclusion Among patients with previous mitral valve surgery, performing a durable mitral isthmus line facilitated by ethanol infusion into the vein of Marshall is feasible and acutely successful.