Our control group was selected to have no SEC, NSR, dilated LA >4.0 cm and no significant MR. We selected such a control population to try to isolate SEC as a single variable. Control patients also had a high prevalence of manifest cardiac disease. Comparison of the two groups (Tables le1, le2) revealed no significant differences in the prevalence of cardiovascular risk factors, coronary artery disease, CHF, prosthetic valves, history of AF or LV dysfunction. A high prevalence of CVA was noted in both the groups. This reflects the referral bias intrinsic to TEE studies. Despite this referral bias, a higher prevalence of CVA was noted in patients with SEC as compared with the control group, 83% versus 56%, p = 0.02. Patients with SEC had a larger LA, 5.6 versus 4.9 cm, p < 0.0001. Patients with SEC had a lower mean LAAEV, 38 versus 56 cm/s, p = 0.001. Fifty-eight percent of patients with SEC had LAAEV <40 cm/s compared with only 5% of controls. Importantly, 13% of patients with SEC had LA thrombus as compared with none in the control group, p = 0.02.