Introduction: Spontaneous echo contrast (SEC) is frequently observed in patients with atrial fibrillation (AF). SEC represents red blood cell aggregates associated with increased thrombogenecity, which may produce larger thrombus formation. This can result in larger infarctions and severe stroke.
Hypothesis: Thrombus characteristics occluding the intracranial artery may differ between AF patients with concomitant SEC and those without.
Methods: This was a post hoc analysis of prospective cohort. Acute stroke patients with non-valvular AF who underwent transesophageal echocardiography and thin-section (1 or 1.25 mm) noncontrast CT between January 2008 and December 2014 were considered for this study. The volume and the density of thrombus were measured semi-automatically using three-dimensional image software, and compared between the patients with SEC and those without.
Results: Among 368 patients considered, thrombus was identified in 135 patients. Of the135 patients, 67 (49.6%) had SEC. The frequency of SEC was not different between patients with identified thrombi and those without (P=0.146). Thrombus volume was larger in the patients with SEC than those without (median [interquartile range], 75.0 mm3 [46.1-142.9] versus 55.9 mm3 [30.3-91.8]; P=0.013). As the degree of SEC increased, the thrombus volume increased (P=0.025). On multivariate analysis, the presence of SEC was independently associated with thrombus volume. (P=0.008). Linear regression analysis showed positive association between initial National Institute of Health Stroke Scale scores and thrombus volume (P<0.001). However, thrombus density was not different between patients with SEC and those without (P=0.226).
Conclusions: This study suggests that increased thromogenecity by SEC in patients with AF might produce larger intracardiac thrombi and embolization, which resulted in larger thrombi occluding the intracranial artery and more severe stroke.