An electromagnetic cardiac assembly adapted to assist ventricular output in a human heart includes a magnetic mat adapted for mounting inside a human body near the heart. The mat is made from a material responsive to application of an electromagnetic field so as to be movable into compressive relation with the heart in response to application of the electromagnetic field thereto and movable out of said compressive relation to permit the heart to relax when application of the electromagnetic field is discontinued. The assembly also includes an electromagnetic subassembly adapted for mounting on the human body in functionally cooperative relation with respect to the mat, and an energy dispersion device adapted for mounting between the mat and the heart. The energy dispersion device is constructed and arranged to disperse energy between the mat and the heart.