Mitral regurgitation protects from left atrial thrombogenesis in patients with mitral valve disease and atrial fibrillation

The aim of this study was to test the hypothesis that mitral regurgitation (MR) has a protective effect on the development of left atrial thrombus (LA T)in patients with rheumatic heart disease and atrial fibrillation (AF). Th e study population consisted of 48 anticoagulated patients (mean age = 57.1 +/- 10 years). Predominant mitral stenosis (MS) was present in 14 patients , predominant MR in 14, and a mechanical valve in 20. All patients underwen t detailed transesophageal echocardiography. Severity of MR was based on me asurements of the MR jet by color flow mapping. Patients were divided into two groups: (a) those with MR greater than or equal to 3 + (n = 12, 25%), a nd (b) those without significant MR (n = 36, 75%). A LAT was found in six p atients (12.5%), who also had spontaneous echo contrast (SEC), while anothe r group of 30 patients (62.5%) had SEC only. LAT and/or SEC were present in 2/12 patients (16.6%) with significant MR versus 34/36 patients (94.4%) wi thout significant MR (P < 0.001). in addition to the absence of significant MR, left atrial diameter (LAD) > 60 mm, and severity of MS were also relat ed to the presence of thrombus and/or SEC. Significant MR had a protective effect against thromboembolism, although this effect was abolished if LAD > 60 mm was present. In conclusion, in patients with mitral valve disease an d AF, significant MR protects against LAT formation and systemic embolizati on. This protective effect was lost when LAD was > 60 mm.