Cut-off Limits for Left Atrial Appendage Flow Velocities Associated with Spontaneous Echo Contrast and Thrombus Formation in Mitral Stenosis

Spontaneous echo contrast (SEC) and /or thrombus (THR) in left atrium appendage (LAA) were known to be associated with reduced blood flow velocities, and their frequency was found to be increased in patients with rheumatic mitral valve stenosis (MS). However, cut-off limits of LAA flow velocities relate to SEC and THR formation within the LAA in patients with MS were not investigated. The purpose of our study is to investigate the LAA flow velocity (FV) spectrum in patients of MS with SEC and /or THR, and to determine the cut-off limits of LAA-FV which may be predictive for SEC and non-obliterating THR formation within LAA in these patients. Study population comprised 283 patients (M 102, F 181, mean age 43±26) who underwent transesophageal echocardiography (TEE) because of a pure or predominant MS. Atrial fibrillation was detected in 155 (54.8%) patients, and sinus rhythm was present in the remainder. Peak outward and inward LAA- FV were measured during TEE procedure. Patients with LAA occluded by THR were excluded from the study. Receiver operating characteristics curve (ROC) and cut-off values of peak FV associated with SEC and THR formation within the LAA were investigated. Spontaneous echo contrast and THR within the LAA were detected in 70 (24.7%) and 57 (20.1%) patients, respectively. Patients with SEC, with both SEC and THR, and without SEC or THR were classified as group I, II, and III, respectively. Both the peak outward and inward FV's detected in orifice and apex of LAA were not found to be different (p>0.05). Moreover, outward and inward FV's were not different for each location of LAA (p>0.05). Incidence of atrial fibrillation were higher in group II as compared with group I and III (91.6% vs 38.4% and 46%, p<0.05). Left atrial diameter, mitral valve area, outward and inward FV of LAA were not different between group I and II (p>0.05). However, mitral valve area, outward and inward FV of LAA were higher in group III as compared with group I and II (p<0.05). Cut-off value of FV for SEC in the LAA was 0.15 m/s, and for THR in the LAA was 0.13 m/s. We conclude that LAA FV cut-off limits for SEC in the LAA is 0.13 m/s, and for THR is 0.12 m/s in patients with MS. Prospective follow-up of patients having FV below these limits and without SEC or THR may give additional data concerning the validity and predictive value of these limits.