A proposed index of myocardial staining for vein of Marshall ethanol infusion: an Italian single-center experience

Abstract

Background: Mitral isthmus (MI) conduction block is a fundamental step in anatomical approach treatment for persistent atrial fibrillation (PeAF). However, MI block is hardly achievable with endocardial ablation only. Retrograde ethanol infusion (EI) into the vein of Marshall (VOM) facilitates MI block. Fluorographic myocardial staining (MS) during VOM-EI could be helpful in predicting procedural alcoholization outcome even if its role is qualitatively assessed in the routine. The aim was to quantitatively assess MS during VOM-EI and to evaluate its association with MI block achievement.

Methods: Consecutive patients undergoing catheter ablation for PeAF at Fondazione Toscana Gabriele Monasterio (Pisa, Italy) from February 2022 to May 2023 were considered. Patients with identifiable VOM were included. A proposed index of MS (MSI) was retrospectively calculated in each included patient. Correlation of MSI with low-voltage zones (LVZ) extension after VOM-EI and its association with MI block achievement were assessed.

Results: In total, 42 patients out of 49 (85.8%) had an identifiable VOM. MI block was successfully achieved in 35 patients out of 42 (83.3%). MSI was significantly associated with the occurrence of MI block (OR 1.24 (1.03-1.48); p = 0.022). A higher MSI resulted in reduced ablation time (p = 0.014) and reduced radiofrequency applications (p = 0.002) to obtain MI block. MSI was also associated with MI block obtained by endocardial ablation only (OR 1.07 (1.02-1.13); p = 0.002). MSI was highly correlated with newly formed LVZ extension (r = 0.776; p = 0.001).

Conclusions: In our study cohort, optimal MSI predicts MI block and facilitates its achievement with endocardial ablation only.

Keywords: Catheter ablation; Ethanol infusion; Mitral isthmus; Persistent atrial fibrillation; Staining; Vein of Marshall.

Fig. 1

Low-voltage zones at mitral isthmus after (A) and before (B) vein of Marshall ethanol infusion. Note the collar-shaped lesion around left pulmonary veins. Only a subtle gap towards mitral annulus remains to achieve mitral isthmus block

Fig. 2

Fluorographic right anterior oblique 30° projection was used to encircle myocardial staining area (B). The same area was applied to the same fluorographic acquisition prior to vein of Marshall ethanol infusion (A) in order to calculate only the additional opacity brought by myocardial staining. This is the same patient as in Fig. 1. Optimal myocardial staining predicted ease of mitral isthmus block achievement with endocardial ablation only. On the right, relative pre- and post-ethanol infusion histograms of luminescence

Fig. 3

Receiver operating characteristics curves for prediction of mitral isthmus block for myocardial staining index (on the left) and delta LVZs (on the right). LVZs, low-voltage zones; AUC, area under the curve

Fig. 4

Correlation between myocardial staining index and delta LVZs. LVZs, low-voltage zones

Fig. 5

Correlation between myocardial staining index and ablation time to obtain mitral isthmus block (on the left) and number of radiofrequency applications (on the right). RF, radiofrequency

Fig. 6

Receiver operating characteristics curves for prediction of arrhythmia recurrence for myocardial staining index. AUC, area under the curve

Fig. 7

Kaplan–Meier curves for arrhythmia recurrence at latest available follow-up stratified for MSI values. MSI, myocardial staining index

Fig. 8

Concomitant localized myocardial staining (arrows) and global myocardial staining (polygon)