Mitral regurgitation and left atrial thrombus in rheumatic mitral valve disease. A clinicopathologic study.

A total of 255 consecutive patients with rheumatic mitral valve disease, scheduled for surgery, were studied preoperatively by transthoracic echocardiography in a tertiary care hospital setting. Data were analyzed to determine the relationship between mitral regurgitation (MR) and left atrial thrombus (LAT) found at surgery. An LAT was found in 77 patients (30%). Eighty patients had MR of which 30 were mild, 33 were moderate, and 17 showed severe MR. The LAT had an inverse relationship to MR with the prevalence of the former as follows: 37%, 33%, 9%, and 0% in none, mild, moderate, and severe MR, respectively (p < 0.0001). In atrial fibrillation (AF), the prevalence of LAT in patients with predominant MR was 8.3% vs 54% in patients with predominant mitral stenosis (p < 0.0001). From 150 patients with AF, 13 had severe MR and no LAT was found whatsoever. In sinus rhythm, the prevalence of LAT was 0% in predominant MR and 14.3% in patients with predominant mitral stenosis (p < 0.0001). Of 105 patients in sinus rhythm, 14 had moderate or severe MR, none of whom has LAT. When mitral valve area was greater than 1 cm2, the presence of significant MR practically excluded the risk of LAT. In conclusion, rheumatic MR is protective against LAT formation. Prophylactic anticoagulation of symptomatic rheumatic mitral valve disease with AF is not likely to be beneficial when MR is severe or when sinus rhythm is present, and MR is moderate to severe.