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.