Linear Ablation at the Mitral Isthmus Following Mitral Valve Surgery

Creating conduction block along the mitral isthmus can be challenging because of anatomical factors. Ethanol infusion into the vein of Marshall (EIVOM) effectively facilitates this process. Patients with prior mitral valve surgery are at high risk for atrial fibrillation and atrial tachycardia. The feasibility and outcomes of EIVOM and mitral isthmus ablation in these patients remain unclear.

The aim of this study was to evaluate the feasibility, safety, and durability of EIVOM and mitral isthmus ablation in patients with prior mitral valve surgery.

Consecutive mitral valve-operated patients undergoing EIVOM and mitral isthmus ablation were retrospectively included. Feasibility and outcomes were evaluated and compared with a propensity score-matched control group.

The study group had a mean age of 64 ± 12 years and a mean left atrial volume index of 56 ± 18 mL/m²; 53.7% of patients were male. Patients with mitral valve replacement (74.1%), 52.5% of whom received mechanical valves, were included. EIVOM was successful in 92.6% of patients, with the acute mitral isthmus block achieved in 88.9% of patients. Propensity-weighted analysis with a control group of patients with no history of mitral valve surgery (n = 72) showed similar EIVOM success rates between groups (91.5% vs 91.7%; P = 0.76) and comparable VOM dissection rates (6.4% vs 1.4%; P = 0.30). The proportion of acutely unblocked mitral isthmus was higher in the study group (12.8% vs 5.5%; P = 0.073). Freedom from atrial tachycardia/atrial fibrillation at 1 year was not statistically different (55.3% vs 73.6%; P = 0.12).

EIVOM and mitral isthmus ablation are feasible and acutely successful after mitral valve surgery.