Fibronectin is a polymorphic and multi functional glycoprotein that plays a wide-ranging role in hemostasis, In this study, it was aimed to determine plasma fibronectin levels and evaluate its possible role in left ventricular (LV) thrombus formation following acute myocardial infarction (AMI). We have determined clinical, echocardiographic, and biochemical parameters in 97 consecutive patients (aged 59 13; 87 men/10 women) with First anterior AMI. Two-dimensional echo cardiography was performed on Days 1, 3, 7, 15, and 30. Blood samples were obtained within 24-48 h after the onset of symptoms, The study also included 30 healthy control subjects. Plasma fibronectin levels were significantly higher in patients with AMI than control subjects (38 +/- 13 vs. 25.2 +/- 8.7 mg/dl, P=.0001). LV thrombus was detected in 20 (20.6%) of 97 patients. Plasma fibronectin levels were significantly higher in patients with LV thrombus (Group 2) than in patients without LV thrombus (Group 1) (44.5 +/- 11 vs. 36.1 +/- 13.4 mg/dl, P =.01). Although univariate analysis showed that plasma fibronectin levels were higher in patients with thrombus, multivariate analysis showed that plasma fibronectin levels were not an independent predictor of LV thrombus formation (P=.059). In multivariate analyses, only peak creatine phosphokinase (CPK) level and LV wall motion score index (WMSI) were independent predictors of thrombus formation (P=.007 and P=.0001, respectively). These results suggest the increased plasma fibronectin levels may be one of the risk factors for LV thrombus formation after AMI. However, further studies concerning the relation between plasma fibronectin levels and LV thrombus formation are necessary. (C) 2002 Elsevier Science Ltd. All rights reserved.