Significance of manifest localized staining during ethanol infusion into the vein of Marshall

Background

Localized staining due to venule injury is attributable to ethanol infusion into the vein of Marshall (Et-VOM).

Objective

The purpose of this study was to investigate adverse outcomes of localized staining during Et-VOM in patients undergoing ablation for atrial fibrillation.

Methods

Two hundred four patients (age 64 ± 10 years; 153 male) were sorted based on the aspect of localized staining. Staining of atrial myocardium that spread uniformly along the VOM vascular tree following selective VOM venography was considered normal, in contrast to predominantly localized staining that spread concentrically from a focal point due to vascular injury. Outcomes between the 2 groups were compared.

Results

Localized staining was observed in 27% of patients. No patients developed clinically significant pericardial effusions during Et-VOM; however, 7 patients developed pericardial effusions on the first postprocedural day (3.6% in patients with vs 3.4% in patients without localized staining). No significant difference was found in achievement of acute mitral isthmus (MI) block (96% vs 98%) and size of the endocardial low-voltage area (8.5 ± 4.1 cm² vs 9.3 ± 5.3 cm²) in patients with and without localized staining, respectively. Long-term follow-up was not impacted by localized staining. Freedom from recurrent atrial tachyarrhythmias (66% vs 76%) and durability of MI block (57% vs 54%) were not significantly different with and without localized staining. There were no cases of rehospitalization for pericarditis, chronic pericardial effusion, or heart failure.

Conclusion

In our study, localized staining was frequent but was not associated with clinically relevant impact or disadvantages.

Introduction

Creating conduction block at the mitral isthmus (MI) with endocardial radiofrequency catheter ablation (RFCA) by connecting the mitral annulus to the ostium of the left inferior pulmonary vein (PV) is an effective treatment of persistent atrial fibrillation (AF) and perimitral flutter.^1,2 However, achieving bidirectional MI block is technically challenging and carries a risk of complications.¹ To overcome these difficulties, chemical ablation by ethanol infusion into the vein of Marshall (Et-VOM) has been developed.^3,4

The vein of Marshall (VOM) is anatomically linked to the MI and is an embryonic remnant of the left superior vena cava. It contains epicardial muscular bundles that connect left atrial (LA) myocardium to coronary sinus (CS) musculature—connections that have been implicated in the maintenance of atrial tachyarrhythmia (ATa).5, 6, 7, 8 Et-VOM is designed to ablate these epicardial muscular bundles as well as portions of the LA myocardium, thus facilitating MI block.^6,9, 10, 11, 12 Recently, the VENUS (Vein of Marshall Ethanol iNfusion in Untreated perSistent Atrial Fibrillation) trial demonstrated the advantage of adjunctive Et-VOM over RFCA alone in reducing recurrent AF at 1 year in patients undergoing ablation for persistent AF.¹²

Localized staining commonly occurs during Et-VOM, presumably caused by injury to VOM venules, and is visualized as leakage of contrast medium from a focal point of origin. This aspect may prompt operators to discontinue the procedure, as the risk for cardiac tamponade may increase with the vascular lesion.¹³ However, despite the high incidence of localized staining, few reports have described this potential complication and its clinical significance. We sought to examine whether manifest localized staining during Et-VOM was associated with adverse outcomes and to describe its management in patients undergoing de novo ablation for persistent AF.