Left atrial thrombi(LAT) and spontaneous echo contrast(SEC) are known as major risk factors for thromboembolic complication in patients with mitral valvular heartdisease. Recent clinical introduction of transesophageal echocardiography(TEE) makes it possible to improve the diagnostic accuracy of these risk facors compared to conventional transthoracic echocardiography(TTE). The aims of the present study were to evaluate diagnostic accuracy of TEE for detection of LAT and to determine if clinical and echocardiographic variables can predict the presence of LAT and/or SEC at TEE.

From July 1991 to April 1993, both TTE and TEE were performed in 84 patients with mitral valvular heart disease before open heart surgery. The incidence and diagnostic accuracy of TTE and TEE for LAT detection were confirmed at surgery for mitral valve replacement in all cases. Biplane with 5.0 MHz transducer was used in TEE. The following clinical and transthoracic echocardiographic variables were analyzed:age, totoal or recent embolism, atrial fibrillation, left atrial dimension, ejection fraction, mitral valve area, and mitral regurgitation.

1) THe sensitivity of TEE for detection of LAT was 100%, which was significantly higher than that of TTE(60.8%). There was no statistical difference in specificity of both techniques(98.3% vs 93.4%). In eleven patients (11/24,45.8%), LAT was confined to the left atrial appendage and TEE was far superior to TTE(sensitivity : 100% vs 27.2%) in detection of appendegeal thrombi.

2) SEC was found in 43 patients(51.2%). Patients with SEC had higher rates of LAT(p<0.001) and embolic episodes (p=0.001) than patients without SEC. There was no association between the severity of SEC and the embolic episodes.

3) Patients with SEC or LAT were characterized by more frequently associated with recent embolic episodes, smaller mitral valve orifice, abscence of mitral regurgitation than those without SEC and LAT.

TEE is superior to TTE in detection of LAT and appendegeal thrombi. SEC is frequently noted in TEE and also strongly associated with left atrial blood stasis and left atrial thrombi in mitral valve disease.