Left atrial thrombus(LAT) has long been recognized as a complication of mitral stenosis(MS).The transesophageal echocardiographic approach readily visualize LAT. We evaluated the risk factors for left atrial thrombus in patients with MS using transthoracic(TTE) and transesophageal echocardiography(TEE).

One hundred and forty-three(patients) who had moderate to severe MS were consecutively studied with TTE and TEE. They were 43 males(30%) and 100 females(70%).The mean age was 44±11 years(range 21-70).

Twenty-five patients had at least one episode of embolic events. Ninety-six patients were in atrial fibrillation(AF). LAT was detected in 30 pts(21%) : 16 had thrombus confined to the LA appenge(LAA), 14 to true LA cavity and/or LAA. TTE variables were compared between LAT group and non-LAT group. Univariate predictors of LAT were mitral valve area(MVA)(0.78±0.22cm2 vs 1.05±0.32cm², p=0.001), pressure half time(353±88ms vs 258±118ms, p=0.002). LV ejection fraction(EF)(55±11% vs 62±8%,p=0.008), LA size (58±11mm vs 52±7mm, p=0.033) and AF(p=0.001). Stepwise logistic regression analysis revealed significant independent predictors of LAT to be AF(p=0.02), MVA(p=0.02) and EF(p=0.03).

Left atrial thrombus was not uncommon in patients with rheumatic mitral stenosis. Small mitral valve area and reduced ejection fraction of left ventricle appear to be significant predictors of LAT in mitral stenosis with atrial fibrillation.