Anatomical and electrical remodeling with incomplete left atrial appendage ligation: Results from the LAALA-AF registry.

Background: The anatomical, electrical, and clinical impact of incomplete Lariat left atrial appendage ligation remains unclear. Methods: We studied LAA anatomy pre-and postligation using contrast enhanced-computed tomography (CT) scans in 91 patients with atrial fibrillation (AF) who subsequently underwent catheter ablation (CA). Results: Eleven patients had an incomplete exclusion (12%) with a central leak ranging from 1 to 5 mm. Despite incomplete ligation; the LAA volume were reduced by 67% postprocedurally when compared to preprocedure. In 7 patients with a leak between 1 and 3 mm, therewas a 77% reduction in LAA volume beyond the ligation site suggestive of remodeling of the LAA. In 4 patients with larger (4-5 mm) leak the LAA remnants (LAARs) were slightly larger than those with smaller leaks on follow-up CT scan. Three out of the 4 demonstrated LAA electrical activity during CA and underwent isolation of theLAAostium. Follow-up imaging showed twoof these LAARs completely sealed with no communication with the left atrium. There was no significant difference in the AF recurrence rates between the patients who had a leak versus those with complete ligation (4 of 11 [36%] vs. 22 of 80 [27%]; P = 0.6). Oral anticoagulationwas discontinued in all patients with small leaks and 2 patients with large leaks that sealed completely upon follow-up imaging. There were no strokes or TIAs at 12months. Conclusion: Despite incomplete LAA ligation by Lariat device there is significant anatomical and electrical remodeling that resulted in reduction in LAA size, volume, and electrical activity.