Cardiac memory is characterized by an altered T-wave on electrocardiogram or vectorcardiogram recorded during sinus rhythm, having been induced by a preceding period of abnormal ventricular activation. This phenomenon reflects the dynamic ability of the heart to adapt to new circumstances, in this instance, an altered electrical activation pattern. The result of this adaptation is a changed electrical substrate expressed in cardiac repolarization. The signal transduction mechanisms and ion channel changes that are initiated by altered activation and that contribute to the expression of cardiac memory are the major focus of this review. Studies of non-cognitive memory in central nervous system have provided a paradigm for much of this research.