Left atrial appendage function and pulmonary venous flow in patients with nonrheumatic atrial fibrillation and their relation to spontaneous echo contrast

This study analyzed the relation between frequency of left atrial appendage (LAA) contractions, pulmonary venous flow (PVF) parameters, and spontaneous echo contrast (SEC). Thirty-six patients (22 male, 14 female, mean age 61 plus minus 11 years) with nonrheumatic atrial fibrillation undergoing transesophageal echocardiography were studied. Doppler flow was obtained from both the LAA and the left upper pulmonary vein. Fourier analysis was applied to the LAA signal that exhibited the frequency of LAA contractions. LAA emptying velocity and PVF parameters were determined. There was no relation between velocity and frequency of LAA flow (r = 0.256, P = ns). Among LAA and PVF parameters, patients with left atrial SEC (n = 17) had a lower LAA velocity (16.8 +/- 10.8 cm/sec vs 35.6 +/- 13.2 cm/sec, P < 0.001), a larger LAA area (4.8 +/- 2.2 cm(2) vs 3.0 +/- 1.3 cm(2), P = 0.008), and a reduced systolic velocity time integral of PVF (3.4 +/- 2.2 cm vs 5.4 +/- 2.2 cm, P = 0.017) when compared with patients without SEC. Frequency of LAA contractions was similar between both groups (6.8 +/- 0.4 Hz vs 6.8 +/- 1.0 Hz, P = ns). In conclusion, the rate of LAA contraction does not correlate with LAA flow velocity and SEC. A low left atrial flow expressed by low LAA flow velocity and a reduction in systolic PVF is a major hemodynamic determinant for the occurrence of SEC.