[Laboratory diagnosis of left atrial thrombi in patients with mitral stenosis]

Left atrial (LA) thrombi sometimes occur in patients with mitral stenosis (MS) and may cause systemic embolization resulting in serious and fatal complications. Several clinical techniques are used to detect the presence of LA thrombi, but even echocardiography, the most widely used, has some drawbacks depending on the sizes and locations of the thrombi. This study evaluated D-dimer, fibrinopeptide A(FPA), and thrombin-antithrombin III complex (TAT) as molecular markers for diagnosing the presence of LA thrombi in 26 patients with MS who underwent cardiac surgery. Atrial fibrillation was detected in all patients. Patients with episodes of obvious thromboembolic diseases were excluded. Blood was obtained from the brachial vein before the surgery (3 +/- 1 days; mean +/- SD). The presence or absence of thrombi was confirmed at surgery in all patients. Levels of both D-dimer and TAT were significantly higher in patients with thrombi than in those without thrombi or in normal subjects. FPA levels did not differ significantly between the three groups. The levels of D-dimer and TAT correlated significantly with the weights of the LA thrombi. LA thrombi (ca > or = 2 g) were always confirmed at surgery in patients with levels of D-dimer higher than 200 ng/ml and/or levels of TAT higher than 4 ng/ml. These results indicate that D-dimer and TAT are simple and useful diagnostic markers for determining LA thrombi in patients with MS.