Left atrial thrombi in non-rheumatic atrial fibrillation: assessment of prevalence by transesophageal echocardiography.

To determine the prevalence of left atrial thrombus in hospitalized patients with non-rheumatic atrial fibrillation, 48 patients were consecutively studied with single-plane transesophageal echocardiography. There were 23 males (48%) and 25 females (52%). The mean age was 66 +/- 11 years (range 43-87). Thrombus was detected in 13 patients (27%): 11 were confined to the left atrial appendage, 1 to the atrial body and appendage, and 1 to the left upper pulmonary vein. Prevalence of atrial thrombus was not different among those patients with or without previous stroke [4/16 (25%) vs 9/32 (28%), p = NS] or between patients > 65 years and patients < or = 65 years old (p = NS). Atrial thrombus was detected more frequently in patients with reduced left ventricular global systolic function than in those with normal function [7/14 (50%) vs 6/34 (17%), p < 0.05]. In patients with spontaneous contrast echoes in the left atrium, thrombi were visualized more often than in those without spontaneous echoes [10/24 (41%) vs 3/24 (12%), p < 0.05]. The finding of the atrial spontaneous contrast echoes was more frequent among patients with reduced left ventricular global systolic function [11/14 (78%) vs 13/34 (37%), p < 0.02]. We conclude that in hospitalized patients with non-rheumatic atrial fibrillation the prevalence of left atrial thrombus is high. Reduced left ventricular global systolic function identifies a subset of patients at high risk for formation of thrombus in the left atrium.