Patent ID: 8005533

Claim:
In an implantable system, a method for assessing a patient's myocardial electrical stability, comprising: (a) obtaining an electrogram (EGM) signal using implanted electrodes; (b) identifying, based on the EGM, periods when the patient experiences T-wave alternans; (c) determining, based on the EGM, whether premature ventricular contractions (PVCs) cause phase reversals of the T-wave alternans; (d) determining what percentage of the PVCs cause phase reversals of the T-wave alternans; (e) assessing the patient's myocardial electrical stability based on the determined percentage; and (f) triggering a response based on the results of step (e), wherein step (f) includes: triggering a first type of response when the patient experiences T-wave alternans, but a PVC does not cause a phase reversal of the T-wave alternans; and triggering a second type of response when the patient experiences T-wave alternans and a PVC causes a phase reversal of the T-wave alternans, wherein the second type of response is different from the first type of response and wherein the second type of response includes charging a capacitor.