Left Ventricular Sphericity Index is a reproducible bedside echocardiographic measure of geometric change between acute phase Takotsubo's syndrome and acute anterior myocardial infarction.

•TS and AMI are separate cardiac conditions with similar clinical presentations.•TS have a higher LVSI than AMI, indicating a more spherical left ventricle.•LVSI may be utilised acutely to assist differentiation of acute phase TS and AMI.