A wearable cardioverter defibrillator comprising: a set of electrodes configured for placement on a subject, the set of electrodes at least operable to sense an ECG signal from the subject; means for electrically engaging the set of electrodes to the subject's skin; at least one non-invasive physiologic sensor (18,20) configured for placement on the subject, wherein the at least one non-invasive physiologic sensor (18,20) comprises one or more of a photoplethysmographic sensor and accelerometer sensor; and a controller configured to monitor an output of said at least one non-invasive physiologic sensor (18,20) for detecting a change in a health parameter of the subject being indicative of one or more of a change in subject condition that may be a precursor to potential cardiac arrhythmia or a simultaneously occurring cardiac arrhythmia, wherein responsive to detecting the change, said controller is adapted to activate an alarm for requesting a response from the subject within a predetermined period of time, wherein (i) responsive to receiving the response from the subject within the predetermined period of time, said controller is adapted to inhibit the means for electrically engaging the set of electrodes to the subject's skin, and (ii) responsive to not receiving the response from the subject within the predetermined period of time, said controller is adapted to initiate the means for electrically engaging the set of electrodes to the subject's skin, wherein the set of electrodes comprises a first set of electrodes operable to sense the ECG signal from the subject and a second set of electrodes operable to deliver a therapeutic shock to the subject, wherein the engaging means is adapted to electrically engage the first set of electrodes and the second set of electrodes to the subject's skin, and wherein the controller is operable to initiate the means for electrically engaging (i) the first set of electrodes and (ii) the second set of electrodes, the controller further operable to obtain an ECG signal after the first set of electrodes is electrically engaged and deliver the therapeutic shock, in response to an analysis of the ECG signal obtained after the first set of electrodes is electrically engaged, after the second set of electrodes is electrically engaged. a set of electrodes configured for placement on a subject, the set of electrodes at least operable to sense an ECG signal from the subject; means for electrically engaging the set of electrodes to the subject's skin; at least one non-invasive physiologic sensor (18,20) configured for placement on the subject, wherein the at least one non-invasive physiologic sensor (18,20) comprises one or more of a photoplethysmographic sensor and accelerometer sensor; and a controller configured to monitor an output of said at least one non-invasive physiologic sensor (18,20) for detecting a change in a health parameter of the subject being indicative of one or more of a change in subject condition that may be a precursor to potential cardiac arrhythmia or a simultaneously occurring cardiac arrhythmia, wherein responsive to detecting the change, said controller is adapted to activate an alarm for requesting a response from the subject within a predetermined period of time, wherein (i) responsive to receiving the response from the subject within the predetermined period of time, said controller is adapted to inhibit the means for electrically engaging the set of electrodes to the subject's skin, and (ii) responsive to not receiving the response from the subject within the predetermined period of time, said controller is adapted to initiate the means for electrically engaging the set of electrodes to the subject's skin, wherein the set of electrodes comprises a first set of electrodes operable to sense the ECG signal from the subject and a second set of electrodes operable to deliver a therapeutic shock to the subject, wherein the engaging means is adapted to electrically engage the first set of electrodes and the second set of electrodes to the subject's skin, and wherein the controller is operable to initiate the means for electrically engaging (i) the first set of electrodes and (ii) the second set of electrodes, the controller further operable to obtain an ECG signal after the first set of electrodes is electrically engaged and deliver the therapeutic shock, in response to an analysis of the ECG signal obtained after the first set of electrodes is electrically engaged, after the second set of electrodes is electrically engaged.