The Left Atrial Appendage Ostium: Hotspots for Localized Re-Entry.

OBJECTIVES

The goal of this study was to characterize the location and electrophysiological properties of left atrial appendage (LAA) atrial tachycardia (AT).

BACKGROUND

The LAA has been reported to be a source of AT and atrial fibrillation (AF) triggers.

METHODS

This study retrospectively reviewed ATs mapped to the LAA. Activation and entrainment mapping were used to determine the mechanism and localize each AT circuit/origin.

RESULTS

From 2014 to 2018, a total of 45 patients (mean age 65 ± 10 years; 69% male) had 51 LAA ATs: 43 (84%) after AF ablation and 8 de novo (no prior AF). Overall, 50 (98%) were due to localized re-entry/micro-re-entry, whereas only 1 was a focal triggered AT. All 50 micro-re-entrant LAA ATs were mapped to the anterior base (70%) or LAA ridge (30%), and all were successfully treated with focal ablation; no case required LAA isolation. After successful ablation of the initial AT at the LAA base, 23 (62%) of 37 patients with AF also had inducible macro-re-entrant peri-mitral flutter, but none had AF triggers from inside the LAA.

CONCLUSIONS

LAA ATs are almost always micro-re-entrant in mechanism and originate from either the anterior base or LAA ridge. AT originating from inside the LAA body is very rare. The anterior and ridge aspects of the LAA-left atrium junction seem to be arrhythmogenic hotspots prone to localized re-entry. These ATs are treatable with focal ablation without LAA isolation but are frequently associated with macro-re-entrant peri-mitral flutter.