Managing the Left Atrial Appendage in Atrial Fibrillation: Current State of the Art

A highly-detailed anatomical study of left atrial auricle as revealed by in-vivo computed tomography

The left atrial auricle (LAA) is the main source of intracardiac thrombi, which contribute significantly to the total number of stroke cases. It is also considered a major site of origin for atrial fibrillation in patients undergoing ablation procedures. The LAA is known to have a high degree of morphological variability, with shape and structure identified as important contributors to thrombus formation. A detailed understanding of LAA form, dimension, and function is crucial for radiologists, cardiologists, and cardiac surgeons. This review describes the normal anatomy of the LAA as visualized through multiple imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and echocardiography. Special emphasis is devoted to a discussion on how the morphological characteristics of the LAA are closely related to the likelihood of developing LAA thrombi, including insights into LAA embryology.

Spectral characterization and impact of stepwise ablation protocol including LAA electrical isolation on persistent AF

OBJECTIVES

To study how left atrial appendage electrical isolation (LAAEI) impacts atrial dominant frequency (DF) in patients with long-standing persistent atrial fibrillation (LSPAF).

BACKGROUND

LAAEI is associated with a high probability of freedom from atrial fibrillation (AF) and spectral analysis may identify high-frequency sources. How LAAEI impacts the AF dynamics and the subgroup of LSPAF patients in whom LAAEI would be most beneficial, is unclear.

METHODS

Twenty patients with LSPAF were included in the study. Fast Fourier transforms (FFT) were performed on atrial electrograms recorded from 13 sites in the LA and RA. The highest peak frequency was defined as DF.

RESULTS

There was no significant difference in DF between atrial sites except for at the superior vena cava which had the lowest DF at baseline. Stepwise ablation consisting of circumferential pulmonary vein isolation and a linear ablation set of mitral isthmus and roof significantly reduced the DF within the coronary sinus (CS) (5.93 ± 0.98 Hz vs. 5.09 ± 0.72 Hz, p < .05) and the LA posterior wall (LApos) (6.26 ± 0.92 Hz vs. 5.43 ± 0.98 Hz, p < .01). LAAEI preferentially further decreased the DF at the LApos (p < .01), but not at the CS. In cases where there was < 13.6% reduction in the DF of the LApos following the stepwise ablation, the addition of LAAEI was associated with an increased restoration of sinus rhythm (55%, p < .05).

CONCLUSION

LAAEI in addition to stepwise ablation results in further reduction of the DF in the LApos, which is associated with acute termination of AF and favorable ablation outcome.

Atrial Thrombosis Caused by a Dislocated Left Atrial Appendage Closure Device After Mitral Valve Replacement

A patient with a left atrial appendage occlusion device underwent mitral valve replacement. Later, the patient developed a left atrial thrombosis with thromboembolic myocardial infarction caused by a dislocation of the occlusion device. Exclusion of the device and non-device-based appendage occlusion may have prevented the patient from experiencing postoperative complications (Level of Difficulty: Intermediate.).