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

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Arrhythmias

Background:

• The left atrial appendage (LAA) is recognized as a potential source of atrial tachycardia (AT) and atrial fibrillation (AF) triggers.
• Understanding the specific arrhythmogenic substrates within the LAA is crucial for effective treatment strategies.

Purpose of the Study:

• To precisely characterize the anatomical locations and electrophysiological mechanisms of left atrial appendage (LAA) atrial tachycardias (ATs).
• To evaluate the efficacy of focal ablation for LAA ATs and assess their association with other arrhythmias.

Main Methods:

• Retrospective analysis of patients with ATs mapped to the LAA.
• Utilized activation and entrainment mapping to determine AT mechanisms and localize circuits.
• Assessed outcomes following focal ablation procedures.

Main Results:

• 51 LAA ATs were identified in 45 patients, predominantly (84%) occurring after AF ablation.
• Nearly all (98%) LAA ATs were caused by micro-re-entrant circuits, originating from the anterior LAA base (70%) or LAA ridge (30%).
• Focal ablation successfully treated all LAA ATs without requiring LAA isolation; however, 62% of patients with prior AF also developed inducible peri-mitral flutter.

Conclusions:

• Left atrial appendage (LAA) atrial tachycardias (ATs) are predominantly micro-re-entrant, originating from the anterior base or ridge.
• The LAA-left atrium junction's anterior and ridge regions are identified as arrhythmogenic hotspots for localized re-entry.
• Focal ablation is an effective treatment for LAA ATs, but associated peri-mitral flutter warrants consideration.