System and method for performing a therapeutic and/or diagnostic function in a patient

A method for operating a system for performing a therapeutic and/or diagnostic function in a patient, the method comprising:

• providing an implantable medical device configured for implantation in a patient, the implantable medical device comprising a motion sensor for sensing a motion signal indicative of a motion of a body part of the patient, particularly the patient's chest, or of a motion of the patient as a whole;
• providing a processing arrangement for processing a motion signal obtained by the motion sensor;
• and
• processing, using the processing arrangement, a motion signal sensed by the motion sensor by comparing information derived from said motion signal to a defined signature motion pattern in order to identify a myocardial infarction event.