Contributing factors to formation of left atrial spontaneous echo contrast in mitral valvular disease

Abstract

The formation of left atrial spontaneous echo contrast may relate to blood stasis. This study analyzed the factors contributing to the formation of that contrast. Transesophageal echocardiography, transthoracic echocardiography, cardiac catheterization, and left ventricular angiography were performed in 139 patients, divided into five groups. Predominant mitral stenosis with atrial fibrillation was found in 36 patients (group I); normal porcine valve in the mitral valvular area with atrial fibrillation in 31 (group II); predominant mitral stenosis with normal sinus rhythm in 26 (group III); moderate to severe mitral regurgitation with atrial fibrillation in 25 (group IV); atrial fibrillation with normal mitral valve in 21 (group V). The results showed left atrial spontaneous contrast echo was found in only 1 of 139 patients by transthoracic echocardiography and 62 of 139 cases were detected by transesophageal echocardiography. There was a high incidence of left atrial spontaneous echo contrast in cases of mitral obstruction with atrial fibrillation and enlarged left atrium (group I, 88%; group II, 74%), but a lower incidence in cases with normal sinus rhythm (group III, 4%), atrial fibrillation alone (group V, 16%), and increased left atrial flow velocity (group IV, 9.5%). The diameter of the left atrium was significantly different between presence and absence of left atrial spontaneous contrast echo (54.3 ± 9.2 mm vs. 48.3 ± 8.6 mm, p < 0.01). The mean pressure gradient was similar in groups I and III (14.6 ± 0.6 mHg and 14.4 ± 2.8 mHg, respectively) but different in group II (10.9 ± 3.2 mHg, p < 0.05). Left atrial thrombi were detected in eight patients (15%) who had left atrial spontaneous contrast. It is concluded that (1) transesophageal echocardiography is more sensitive to detect left atrial spontaneous contrast echo than the transthoracic approach; (2) in mitral valvular disease, there is no single responsible factor for the formation of left atrial spontaneous echo contrast (combined mitral obstruction, atrial fibrillation, and enlarged left atrium are all necessary); and (3) the presence of left atrial spontaneous contrast echo indicates severe left atrial blood stasis and may be a warning of thrombus formation.