Procedural details
A total of 129 patients underwent attempted VOM ethanol infusion during
the study period (Table 1). The average age was 64.3 years and 67.4%
were male. Ninety were initial procedures for AF and 39 were redo
procedures. Of the latter group, 56% had permanent PVI upon initial
intraprocedural mapping. Most VOM infusions were preplanned, but a
substantial proportion, including 26% in the group of initial
procedures, were ad hoc . All but one of these were performed
ad hoc to facilitate block for induced mitral annular flutter,
with the additional one done in the case of a suspected ligament of
Marshall trigger for AF after PVI was completed. The ad hoc group
encompassed nearly the entirety of patients with paroxysmal AF
undergoing VOM infusion during an index procedure. Ablation was
restricted to the standard lesion set as depicted in Figure 1 in 88% of
the patients taken for an initial AF ablation but the majority of redo
cases had additional lesions, most commonly SVC isolation/ablation
(69%).
The success rate of VOM infusion was 90%, though improved in follow-up
from a 76% success in the initial years of the study to 100% in 2022.
Reasons for failure of ethanol delivery in twelve patients included
failure to cannulate the CS (1), a left persistent superior vena cava
(SVC) (1), a wire perforation with avoidance of ethanol delivery (1),
targeting of the incorrect vein (2), failure to cannulate the VOM (3),
and failure to identify the VOM (4). Total case fluoroscopy averaged
18.8 minutes but decreased during the study from 34.6 minutes during the
first two years of the study to 10.5 minutes during 2022 (Figure 2). VOM
perforation occurred in two patients (1.6%) including one wherein
ethanol was not delivered. VOM dissection occurred in 8.5% of patients.
These events and procedural success are depicted by procedure order in
Figure 2A. All attempts at acute mitral isthmus block were successful,
irrespective of whether the VOM ethanol infusion was completed.