Abstract
In this group, transoesophageal echocardiography (TOE) shows inter-atrial septal abnormalities in 55–60% of cases. The same abnormal septum is observed in 20% of the normal population. However, when present in a patient with a stroke of unknown cause, is this abnormality responsible for the stroke or the marker for the true cause of stroke? For example, having yellow nails is statistically associated with lung cancer, but does not mean that yellow nails cause lung cancer.