Left Atrial Appendage Contractile Function in Atrial Fibrillation

A high incidence of embolic phenomena is associated with atrial fibrillation (AF) and the left atrial appendage (LAA) is frequently the source of the emboli. Thrombus formation may be due to stasis within the fibrillating and inadequately emptying LAA. Because LAA emptying in AF may be the result of mechanical compression by the adjacent left ventricle, it is possible that left ventricular diastolic filling duration will importantly influence passive emptying of the LAA. We hypothesized that the magnitude of emptying of the LAA in AF is related to the duration of left ventricular diastolic filling which is determined by the ventricular response rate in AF. The objective of our study was to determine the relationship of ventricular response rate in AF to LAA emptying and to assess the influence of sinus rhythm and heart rate on LAA emptying immediately after direct current cardioversion to sinus rhythm. To study this, we used transesophageal echocardiography to measure LAA ejection fraction ([LAAmax—LAAmin]/LAAmax×100%) and evaluated its relationship to left ventricular response rate (VRR) in 26 patients with AF (mean age, 65 ± 7 [1 SD] years). There was a strong inverse relationship between LAA ejection fraction and VRR in AF (r= −0.73; p