Modified Anatomical Ablation Strategy for Mitral Isthmus.

Area of Science:

• Cardiology
• Electrophysiology
• Medical Device Technology

Background:

• Durable mitral isthmus (MI) block is crucial but challenging in persistent atrial fibrillation (AF) ablation.
• Ethanol infusion into the vein of Marshall (EI-VOM) is an adjunct therapy, but optimal ablation extent is unclear.

Purpose of the Study:

• To define the minimal endocardial ablation extent required for MI block post-EI-VOM.
• To evaluate the efficacy and safety of EI-VOM combined with stepwise ablation for persistent AF.

Main Methods:

• Prospective study of 35 persistent AF patients undergoing first-time ablation.
• EI-VOM (11.10 ± 2.24 mL ethanol) followed by bilateral pulmonary vein isolation (PVI), linear ablations, and stepwise MI ablation.
• Primary endpoints: acute MI block, lesion requirements, and 6-month sinus rhythm (SR) maintenance.

Main Results:

• 88.6% of patients achieved acute MI block with an average of 5.03 ± 4.51 endocardial lesions.
• Fewer lesions were needed in smaller left atria (<45 mm).
• EI-VOM facilitated MI block in 90% of cases with partial endocardial ablation; 6-month SR maintenance was 88.5% with zero major complications.

Conclusions:

• EI-VOM synergizes with partial endocardial ablation for MI block, especially in non-dilated left atria.
• Adjunctive coronary sinus ablation is recommended for dilated atria.
• The strategy shows high mid-term efficacy, but non-anatomical factors may influence recurrence.