Role of transesophageal echocardiography in detecting left atrial thrombus and spontaneous echo contrast in patients with mitral valve disease or non-rheumatic atrial fibrillation.

Instances of left atrial (LA) thrombus and spontaneous echo contrast were evaluated by both transthoracic echocardiography (TTE) and subsequent transesophageal echocardiography (TEE) in 50 patients with rheumatic mitral stenosis (Group I) and 52 patients with non-rheumatic atrial fibrillation (Group II). Among these 102 patients, TEE detected LA thrombi in 16 patients (15.7%) and spontaneous echo contrast in 35 (34.3%). In contrast, TTE revealed LA thrombi in only 8 patients (7.8%) and spontaneous echo contrast in only 2 patients (2.0%). All of the LA thrombi and spontaneous echoes detected by TTE were also found by TEE. When TEE was applied, patients with spontaneous echo contrast had a significantly higher incidence of LA thrombus than did those without this echo (42.8% vs 1.5%, p less than 0.01). Spontaneous echo contrast was coexistent in all but one of the patients with LA thrombi (15 of 16, 93.7%). In Group I, the incidence of spontaneous echo contrast for patients with isolated or predominant mitral stenosis was high (68.3%) when TEE was applied, but this echo was not observed in any patient who had more than a moderate degree of mitral regurgitation. In Group II, 7 patients (13.5%) were also found to have spontaneous echo contrast, which could only be detected by TEE. Of these 7 patients, LA thrombus was noted in 4 by TEE, but only in 1 by TTE. Thus, it can be concluded that: (1) TEE is superior to TTE for detecting LA thrombus and spontaneous echo contrast; (2) spontaneous echo contrast in LA is not only frequently encountered in mitral stenosis without significant mitral regurgitation, but is also found in some patients with non-rheumatic atrial fibrillation; and (3) the presence of spontaneous echo contrast is associated with a higher incidence of LA thrombus and may be considered as a warning sign for further formation of LA thrombus.