[Relation between left atrial spontaneous echocontrast and pulmonary venous flow in nonvalvular atrial fibrillation: implications for stratification of thromboembolic risk].

BACKGROUND: The links between pulmonary venous flow (PVF) and left atrial stasis have not been adequately defined in nonvalvular atrial fibrillation. In this setting, we aimed to study the relationship between PVF and the occurrence of left atrial spontaneous echocontrast (SEC) in order to evaluate its clinical relevance in the assessment of the cardioembolic risk. METHODS: We studied by echocardiography 109 patients with nonvalvular atrial fibrillation (65 males, 44 females, mean age 66 +/- 9 years). The left ventricular end-diastolic and end-systolic diameters, the left ventricular fractional shortening, the left ventricular mass, and the left atrial volume were measured by transthoracic approach. The systolic and diastolic peak velocities of PVF, their ratio (pS/pD) and the velocity-time integrals were assessed by means of transesophageal investigation; furthermore, the presence of left atrial SEC or thrombi was recorded. Among clinical data, thromboembolic events occurring within 15 days before the echocardiographic study, history of hypertension and duration of atrial fibrillation were also collected. RESULTS: Left atrial SEC showed a significant correlation with left atrial volume (p < 0.001), detection of thrombi (p < 0.001), thromboembolic events (p = 0.002) and pS/pD ratio (p < 0.001). By multivariate analysis, pS/pD ratio was independently correlated with left atrial volume, age and left ventricular fractional shortening (r2 = 0.29, p < 0.001). The sensitivity and specificity of pS/pD ratio to predict the presence of severe SEC was 73.9 and 62.5%, respectively. CONCLUSIONS: In patients with nonvalvular atrial fibrillation, pS/pD ratio is significantly related to the occurrence of left atrial SEC and seems to be a useful parameter concurring to assess left atrial stasis and thromboembolic risk.