Hyperhomocysteinemia is associated with the presence of left atrial thrombus in stroke patients with nonvalvular atrial fibrillation.

BACKGROUND AND PURPOSE Blood stasis is the fundamental mechanism leading to thrombus formation in the venous system. Homocysteine also poses a significant risk for venous thrombosis through its endothelial toxic and prothrombotic properties. In the present study, we hypothesized that high homocysteine might be associated with thrombus formation in another stasis-related condition, atrial fibrillation. METHODS Forty-two consecutive patients with ischemic stroke caused by nonvalvular atrial fibrillation and admitted within the first day of symptom onset were included. Total fasting plasma homocysteine, serum folic acid, and vitamin B12 levels were measured. All patients were evaluated by transesophageal echocardiography for the presence of a left atrial (LA) thrombus. Homocysteine and vitamin levels were compared between groups with or without LA thrombus. RESULTS Transesophageal echocardiography revealed LA thrombus in 20 patients. Mean homocysteine levels were significantly higher in patients with LA thrombus (20.75 versus 13.34 micromol/L, P<0.001). Multivariate logistic regression analysis showed that the effect of high homocysteine was independent of other clinical or echocardiographic variables known to increase LA thrombus (P=0.017). There was no difference in vitamin B12 levels between groups (P=0.118), whereas the mean folic acid level was significantly lower in patients with LA thrombus (P=0.004). CONCLUSIONS High plasma homocysteine conveys an independent risk for LA thrombus formation in patients with stroke caused by nonvalvular atrial fibrillation. This finding further supports the thrombogenic role of high homocysteine in conditions associated with blood stasis.