Comparative evaluation of transthoracic and transesophageal echocardiography in detection of left atrial thrombus before percutaneous transvenous mitral commissurotomy. Do all patients need transesophageal examination?

We postulated that the sensitivity of transthoracic echocardiography in detection of left atrial cavity or appendage thrombi is better in south-east asian patients with rheumatic mitral stenosis. This was considering that these patients are generally younger, have lesser body weight and thinner chest walls resulting in better transthoracic echogenecity than their western counterparts. We prospectively performed transthoracic and transoesophageal echocardiography in 150 consecutive Indian patients (mean age 28.8+/-7.2 years; 78 men) being evaluated for percutaneous transvenous mitral commissurotomy. The overall sensitivity of transthoracic echocardiography was 74% (95% C.I. 59-88%). This was significantly higher than the pooled estimate from five western reports which evaluated similar patients (overall sensitivity 12%; 95% C.I. 0-25%; P<0.0001). The sensitivity rose to 83% when patients with poor echogenecity were excluded. Amongst patients with good echogenecity (81% patients) the diagnosis of left atrial thrombi was correctly made or suspected on transthoracic examination in all patients subsequently shown to have thrombi on transoesophageal echocardiography. Significant savings in cost may be safely achieved by limiting transoesophageal echocardiography to patients in whom left atrial cavity or appendage is not adequately visualized on transthoracic examination due to poor echogenecity, or in whom there are shadows suggestive but not diagnostic of thrombi.