Impact of technical aspects of vein of Marshall ethanol infusion on mitral isthmus block for persistent atrial fibrillation ablation

FIGURE 1. Selective venography of the EIVOM and LVA measurement. (A) The balloon at the proximal VOM was inflated at 7 atm, and selective venography displayed one small tortuous VOM with two distal branches, coursing upward behind the ostium of the LAA (the PentaRay catheter at the LAA). While in panel (B), after balloon inflation at 8 atm, repeated venography showed another long and straight proximal branch of VOM [invisible in panel (A)], indicating the balloon was completely occluded in panels (B) and not in panel (A). This example highlighted the importance total occlusion of the OTW before ethanol infusion. (C,D) LA substrate mapping pre- and post- EIVOM. Note the size of LVA (white arrow) markedly increased from 7.4 cm2 pre-EIVOM to 18.4 cm2 post-EIVOM. RAO, right anterior oblique; PA, postero-anterior; LSPV, left superior pulmonary vein; RSPV, right superior pulmonary vein; LIPV, left inferior pulmonary vein; RIPV, right inferior pulmonary vein; LAA, left atrial appendage; MA, mitral annulus; LVA, low voltage area.

FIGURE 2. An example of MIth linear ablation and validation of MIth block. (A) LA substrate mapping post-EIVOM displayed a patchy LVA (white arrow) in the MIth region. (B) An entire MIth lesion line was created connecting the MA and the inferior aspect of LIPV’s ostium, across the EIVOM-related LVA. Note epicardial CS ablation was applied after failure of MIth block by endocardial MIth ablation. (C,D) Tracings were surface ECG lead II, V1, PentaRay1,2 -PenraRay19,20, CS9,10 - CS1,2 and ABL1,2. (C) Pacing from PentaRay13,14 (positioned within LAA) displayed the proximal to distal CS activation sequence. The interval from LAA pacing to CS1,2 WAS 146 milliseconds (ms). (D) The ablation catheter tip (ABL) was positioned just lateral to the MIth line [shown in panel (B)]. The interval from pacing from ABL1,2 to CS1,2 was 176 ms, which was longer than that from pacing from LAA to CS1,2 (146 ms), indicating the MIth line was blocked. LSPV, left superior pulmonary vein; RSPV, right superior pulmonary vein; LIPV, left inferior pulmonary vein; RIPV, right inferior pulmonary vein; LVA, low voltage area; MIth, mitral isthmus; CS, coronary sinus.

FIGURE 3. Comparison of RF ablation parameters between the “EIVOM first” and “RFCA first” group. The average ablation index (AI) (A), contact force (B), and number of lesions (C) was significantly greater in “RFCA first” group than those in “EIVOM first” group.

FIGURE 4. Correlation of ethanol volume with the size of ΔLVA at the MIth region. Spearman’s coefficient = 0.66, P < 0.001.

FIGURE 5. The ROC curve for the ethanol volume and comparison of ATa-free survival. Panel (A) displayed the ROC curve for the ethanol volume. Area under the curve (AUC) was 0.827, 95% CI: 0.686–0.967, P = 0.008. Panel (B) showed the Kaplan–Meier plots of ATa-free survival in patients with MIth block and those without during one year’s follow-up. The ATa-free survival was significantly higher in patients with successful MIth block than that in those without (Log-rank test, P = 0.01). ATa, atrial tachyarrhythmias.

FIGURE 6. Central illustration: Technical aspects of EIVOM on acute MIth block.