Diagnosis of left atrial thrombi in mitral stenosis--usefulness of ultrasound techniques compared with other methods

The purpose of this study was to evaluate various methods of diagnosis of left atrial thrombi (LAT) in patients (pts) with mitral stenosis (MS). From 1980 to 1990, 581 pts with MS have undergone open mitral commissurotomy (n = 169) or valve replacement (n = 412). All pts had transthoracic 2D echocardiography (TTE), 101 transoesophageal echocardiography (TEE), 192 a left atrial angiography (A) (from a left ventricular injection if associated mitral regurgitation grade 3 (n = 154) or from an injection in the pulmonary artery (n = 38) and 229 a coronary angiography (CA). Tomodensitometry (TD), nuclear magnetic resonance (NMR) and 111 Indium platelet imaging (IPI) were performed in some cases, 2, 8 and 5 respectively. All these examinations were carried out in the month before surgery. LAT was found by the surgeon in 43 pts (7%). The site was left atrial appendage in 26 cases (60%) and left atrial cavity in 17 cases. Sensitivity (Se), specificity (Sp) of TTE/TEE/A/CA were the following: TTE, Se% 28, Sp% 99; TEE, Se% 83, Sp% 97; A, Se% 28, Sp% 99; CA, Se% 14, Sp% 100. Specificity was high with all methods but sensitivity was high only with TEE and poor with other methods because of difficulty in detecting thrombi of the left atrial appendage. Specificity and sensitivity of TD, NMR and IPI require more information. False-negative cases are possible with NMR (1 case) and IPI (1 case) in well established LAT. We conclude: TEE is the easiest way to detect LAT, particularly when located in the left atrial appendage. It should be carried out systematically before percutaneous mitral valvuloplasty or surgery.