CLINICAL IMPLICATIONS AND FACTORS RELATED TO LEFT ATRIAL SPONTANEOUS ECHO CONTRAST IN CHRONIC NONVALVULAR ATRIAL-FIBRILLATION

The mechanisms leading to formation of spontaneous echo contrast (SEC) , a smoke-like echo on echocardiography, are still controversial. To f urther explore the clinical implications and factors related to SEC fo rmation, the correlation among echocardiographic variables, hematologi c parameters or platelet aggregability, and the occurrence of SEC was studied in 119 patients with chronic nonvalvular atrial fibrillation. There were 75 men and 44 women with a mean age of 65 +/- 10 years (ran ge 38-88). Left atrial SEC was detected in 39 patients (33%) by transe sophageal echocardiography. Patients with history of systemic embolism were more frequently found to have left atrial SEC and left atrial th rombus by univariate analysis. Multivariate analysis showed that left atrial SEC (p < 0.001) was the only independent predictor of history o f systemic embolism. Age, sex, left atrial or left ventricular dimensi on, left ventricular ejection fraction, antiplatelet or anticoagulant therapy and the percentage of lone atrial fibrillation were not signif icantly different between patients with and without left atrial SEC. A mong the hematologic parameters, higher hematocrit was found in patien ts with left atrial SEC, while white blood cell and platelet counts we re comparable in both groups. Platelet aggregability with different co ncentrations of inducers, adenosine diphosphate and collagen, was eval uated by the turbidimetric method in 15 patients with left atrial SEC and in 42 patients without left atrial SEC who were not receiving anti platelet or anticoagulant therapy. No significant difference was found in platelet aggregability using four inducer concentrations between t wo groups of patients. It is therefore concluded that SEC formation is related to the hematocrit level in patients with nonvalvular atrial f ibrillation, and the results also support the hypothesis that left atr ial SEC comes from erythrocyte aggregation.