The ligament of Marshall as a therapeutic target in atrial fibrillation: from anatomy to catheter-based and surgical management—a narrative review
Year: 2026
Type: review
Abstract: Background and Objective: Long regarded as an inconsequential embryological remnant, the ligament of Marshall (LOM) is now recognized as a treatable component of the atrial fibrillation (AF) substrate. This review synthesizes the anatomical, electrophysiological and clinical evidence behind that shift and compares the two routes to the LOM: percutaneous retrograde ethanol infusion into the vein of Marshall (EIVOM) during catheter ablation, and direct division during thoracoscopic surgery. Both act on the same epicardial structure; only the route of access differs. Methods: A structured literature search of PubMed, Embase and Web of Science covered the embryology, anatomy, histology and electrophysiology of the LOM and clinical studies of both routes. Two authors screened and selected records independently. Given the heterogeneity of study designs, findings were synthesized narratively. Key Content and Findings: The LOM is a neuro-muscular remnant of the embryonic left superior vena cava that contributes to AF through three mechanisms: triggers arising from insulated myocardial “Marshall bundles”, autonomic modulation via adjacent ganglionated plexi, and preferential conduction across the mitral isthmus. Five randomized trials of EIVOM-based strategies have enrolled more than 1,100 patients; pooled analysis shows improved 12-month freedom from any atrial arrhythmia (risk ratio 1.16, 95% confidence interval: 1.04–1.29; number needed to treat 10) and less repeat ablation, without excess major complications (2.5% vs. 2.8%) but with more overall complications and longer fluoroscopy. Crucially, no trial has tested ethanol infusion in isolation; the observed benefit reflects composite lesion sets. Thoracoscopic division interrupts the entire ligament independent of venous anatomy but has never been a randomized variable; randomized evidence for thoracoscopic and hybrid strategies overall ranges from neutral (CASA-AF) to positive (CONVERGE, HARTCAP-AF). Guidelines recognize both as options in selected patients without mandating routine LOM division. Conclusions: The LOM is a reproducible, anatomically defined target reachable percutaneously or by surgical division within a comprehensive AF ablation strategy. The supporting evidence is markedly asymmetric: randomized data exist for EIVOM-based strategies but never for ethanol infusion alone, none at all for surgical division, and the two routes have never been compared head-to-head. Its incremental benefit beyond pulmonary vein and posterior wall isolation remains undefined.
Source: Journal of Thoracic Disease
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7224121033