Background: The frequency of occurrence of left atrial thrombi, and the effect of anticoagulation in patients with rheumatic mitral stenosis and atrial fibrillation is not well established. This study was conducted to evaluate the occurrence of left atrial body and left atrial appendage clots in patients with rheumatic mitral stenosis and atrial fibrillation, and to document the effect of long-term anticoagulation on clot dissolution.
Methods and results: Consecutive patients with severe rheumatic mitral stenosis and atrial fibrillation were assessed by transesophageal echocardiography. Those with left atrial body or left atrial appendage clots were anticoagulated with oral nicoumalone. Transesophageal echocardiography was then repeated in patients on anticoagulation who were on regular follow-up, and in whom percutaneous transvenous mitral commissurotomy could be considered. Of the 490 patients studied, 163 had left atrial body or left atrial appendage clots. A repeat transesophageal echocardiographic examination was done in 50 patients who had optimal anticoagulation for a period of 6 months. Only 2 of the 17 patients who had left atrial body clots had successful clot dissolution after long-term anticoagulation, while the left atrial appendage clots disappeared in 31 of 33 patients (p<0.001).
Conclusions: Left atrial clots are present in a third of patients with severe rheumatic mitral stenosis and atrial fibrillation. Isolated left atrial appendage clots in patients with rheumatic mitral stenosis and atrial fibrillation can disappear with long-term anticoagulation, while thrombi that extend into the left atrial body may persist despite optimal anticoagulation.