A system comprising an implantable medical device (IMD). The IMD comprises
a ventricular heart signal sensing circuit to provide a ventricular heart
signal, at least one sensor operable to provide an electrical signal
representative of patient activity, a sensor interface circuit coupled to
the at least one sensor to provide an activity signal, and a controller
circuit coupled to the heart signal sensing circuit and the sensor
interface circuit. The controller circuit is operable to determine
whether ventricular ectopy occurs during recovery from exercise using the
heart signal, and to set at least one warning indicator if ventricular
ectopy occurs during the recovery from exercise.