A device and algorithm for a combined cardiomyostimulator and a cardiac pacer-cardioverter-defibrillator. In particular the present invention operates, in a first embodiment, to deliver stimulation to a skeletal muscle 3 grafted about a heart 2; sense depolarizations of a patient's heart; measure the intervals separating successive depolarizations of the patient's heart; define first and second interval ranges; determine the number of the measured intervals falling within the first and second interval ranges; inhibit the delivery of stimulation to a skeletal muscle grafted about a heart upon the sensing of a depolarization within the first or second interval range; detect the occurrence of a first type of arrhythmia when the number of the measured intervals falling within the first interval range equals a first predetermined value; detect the occurrence of a second type of an arrhythmia when the number of the intervals falling within the second interval range equals a second predetermined value; deliver a first type of arrhythmia therapy in response to the detection of the first arrhythmia; and deliver a second type of arrhythmia therapy in response to the detection of the second arrhythmia, the second type of arrhythmia therapy having a cardiac stimulation component and a skeletal muscle component.