Systemic emboli related to atrial thrombi in severe mitral stenosis are a well known complication of percutaneous ballooon dilatation of the mitral valve(PMV). The purpose of this study was to identify factors that predicted left atrial thrombi and systemic embolism in patients with severe mitral stenosis.

Retrospective study of 79 patients with severe mitral stenosis by analysis of videotape having the record for transthoracic(TTE) and transesophageal echocardiography(TEE) was done over a 24 month period.

The twenty eight patients(35%) had left atrial thrombus, and fifteen patients(19%) had experience of systemic embolization. Both appeared most commonly in the ages of 50 years. In thrombus group, the incidence of atrial fibrillation was more frequent(p=0.001), left atrial size larger(p=0.0014), and mitral valve area(p=0.0353) and ejection fraction of left atrial appendage(p=0.037) were lesser than non-thrombi group. In left atrial appendage(LAA) thrombus group, the left atrial dimension(p=0.0282) and the ejection fraction of LAA(p=0.008) were lesser than those in the left atrial thrombus group. In embolism group, the age was older(p=0.0212) and the incidence of atrial fibrillation tended to be more frequent(p=0.05470 than non-embolism group.

In severe mitral stenosis, the formation of left atrial thrombus was related to presence of atrial fibrillation, size of left atrial dimension and area of mitral valve. And the thrombus of LAA was related to low ejection fraction of left atrium. The predictors of embolism in severe mitral stenosis were age and the presence of atrial fibrillation. The TEE was the useful diagnostic tool in detecting the thrombus of left atrium and LAA before PMV and the patients with predictors of thromboembolism should be treated more actively in severe mitral stenosis.