Cardiac conduction abnormalities and arrhythmias are linked to stroke, heart failure, and sudden cardiac death and continue to be a major cause of death and disability worldwide. However, the evaluation of cardiac conduction remains challenging in the clinical setting. Electromechanical Wave Imaging (EWI) [1] was recently developed to map the transient displacements [1] and deformations [2] of the myocardium following electrical activation in multiple 2D imaging planes and was shown to be highly correlated with electrical activation times. In this study, we demonstrate the feasibility of performing EWI in isolated rat hearts using a 3D ultrafast ultrasound scanner.