Clinical significance of anterior mitral leaflet fibrillation in patients with nonvalvular atrial fibrillation: comparison with blood flow and wall motion of the left atrial appendage.

Abstract

Diastolic fibrillation of the anterior mitral leaflet (AML) is seen in patients with atrial fibrillation (AF). However, its clinical significance has been unclear. On the other hand, reduced blood flow velocity in the left atrial appendage (LAA) may be associated with LA thrombus formation. In this study, we investigate the relationship between the flow velocity and the wall motion velocity of the LAA and diastolic fibrillation of the AML in patients with nonvalvular AF. We performed transthoracic echocardiography (TTE) in 45 consecutive patients with chronic nonvalvular AF. The LAA flow velocity was measured by pulsed Doppler echocardiography with the sample volume positioned at the center of the LAA. The LAA wall motion velocity was measured by pulsed Doppler tissue imaging (DTI) with the sample volume at the medial wall of the LAA. The AML fibrillation velocity was measured by pulsed DTI with the sample volume at the AML tip. The AML fibrillation velocity could be measured in 44 patients (97.8%), and the LAA flow and wall motion velocities were measurable in 35 (77.8%) and 42 (93.3%) patients, respectively. The AML fibrillation velocity had a range from 4 to 21cm/s and showed significant positive correlation with the LAA flow velocity (r=0.82, P<0.001) and the wall motion velocity (r=0.80, P<0.001) of the LAA. An AML fibrillation velocity of ≤7cm/s predicted patients having a tendency to LA thrombus formation (LAA flow velocity ≤20cm/s) with high sensitivity (87.5%) and specificity (88.9%). The AML fibrillation velocity seems to be a viable substitute for the LAA flow velocity in the detection of flow stagnation in the LA.