3.2 | Procedural characteristics
Vein of Marshall ethanol infusion was successfully performed in 19 patients (86%). VOM-EI was not performed in three patients due to a missing VOM, a too small VOM diameter for cannulation, and a VOM dissection during cannulation. Among patients with successful VOM-EI, radiofrequency ablation of the mitral isthmus was performed during the same procedure before VOM-EI in 8 patients (42%), without achieving mitral isthmus block. Ancillary radiofrequency ablation during the VOM-EI procedure included pulmonary vein isolation in 11 patients (58%), roof line ablation in 8 (42%), left atrial defragmentation in one (5%), superior vena cava isolation in two (11%), and cavotricuspid isthmus ablation in 4 patients (21%).
During VOM-EI, a median of 4.0 ml (IQR 3.0-6.0) 96% ethanol was infused into the VOM. Perimitral flutter was present during VOM-EI in 12 patients (63%) with termination during chemical ablation in 4 (33%; Figure 4), and cycle length prolongation in 3 (25%). Chemical ablation directly induced bidirectional mitral isthmus block in 7 of 19 patients (37%). In the remaining 12 patients (63%) bidirectional mitral isthmus block was successfully achieved with ancillary radiofrequency catheter ablation, for which we targeted the endocardial, annular side of the mitral isthmus in 11 patients (92%) and the pulmonary venous side in 3 patients (25%). Ancillary radiofrequency catheter ablation within the CS was performed in six patients (50%) after VOM-EI.
The median low-voltage area in the lateral left atrium increased significantly from 3.1 cm2 (IQR 0-7.9) before to 13.2 cm2 (IQR 8.2-15.0; P = 0.02) after VOM-EI. Low-voltage area induced by VOM-EI correlated significantly with the volume of ethanol injected (P = 0.03; Figure 5).
Creatine kinase (CK) and creatine kinase myocardial band (CK-MB) were 124 U/L (IQR 101-302) and 7.3 µg/L (IQR 5.7-10.3), respectively, on the evening of the procedure, without significant change in the next morning (141 U/L [IQR 89-293] and 8.2 µg/L [IQR 4.5-9.5], respectively; Figure 6). High-sensitive cardiac troponin-T (hs-TnT) measured 330 ng/L (IQR 221-516) the evening of the procedure with a significant increase the following morning (598 ng/L [IQR 382-769]; P = 0.02).