Vein of Marshall Ethanol Infusion First for Mitral Isthmus Linear Ablation

Mar 23, 2022
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Authors:
Gillis K, O’Neill L, Wielandts JY, et al.
Citation:
Vein of Marshall Ethanol Infusion as First Step for Mitral Isthmus Linear Ablation. JACC Clin Electrophysiol 2022;8:367-376.
Summary By:
Thomas C. Crawford, MD, FACC

Quick Takes

  • The combination of vein of Marshall ethanol ablation with RF ablation is associated with a very high rate of mitral isthmus block.
  • The present study suggests that ethanol ablation should be performed as a first step during mitral isthmus ablation.
  • These findings should be confirmed in future studies.

Study Questions:

What is the added value of vein of Marshall ethanol infusion (VOMEt) as a first step in facilitating radiofrequency (RF)-guided mitral isthmus (MI) block?

Methods:

Seventy patients planned for MI ablation were randomized 1:1 to VOMEt as a first step preceding RF (endocardial and epicardial, VOMFIRST group) versus RF ablation as a first step preceding VOMEt (RFFIRST group). The study endpoint was incidence of MI block after RF ablation and after the two steps.

Results:

In VOMFIRST, VOMEt was successful in 30/35 patients (86%) resulting in a low voltage area of 12 ± 7.4 cm and MI block in 2/35 patients (6%). As compared to RFFIRST, VOMFIRST was associated with higher incidence of MI block after endocardial (11% vs. 46%, p < 0.001) and epicardial ablation (43% vs. 94%, p < 0.001), with less endocardial applications (11 vs. 4 respectively, p < 0.001) and comparable epicardial applications. Incidence of MI block after the two steps was 63% versus 94% (p = 0.001) in RFFIRST versus VOMFIRST, respectively. Additional touch-up RF ablation in both groups resulted in final MI block in all but one patient (99%).

Conclusions:

VOMEt as a first step in RF-guided MI line ablation significantly reduces the number of RF applications needed to achieve MI block, even if the sequence of the ablation steps does not affect the final incidence of block.

Perspective:

There are two scenarios in which the achievement of bidirectional block at the MI is desirable: in the improvement of long-term outcomes of persistent atrial fibrillation RF ablation (not consistently demonstrated), and in the management of MI flutter. The achievement of bidirectional block with RF ablation alone done with both endocardial and epicardial energy applications is challenging and often impossible. Ethanol injection in the vein of Marshall has been previously shown to facilitate the success of RF ablation of the MI. This research shows that performing ethanol ablation before RF ablation may be more effective than using ethanol ablation as a bailout should RF ablation fail. Nota bene, this is a study of acute procedural outcomes, not clinical outcomes during follow-up.

Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure

Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Atrial Flutter, Catheter Ablation, Epicardial Mapping, Ethanol, Heart Failure, Pulmonary Veins, Radiofrequency Ablation


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