Patent ID: 8160697

Claim:
A method of cardiac treatment using an implantable medical device system having implanted electrodes and an energy storage system for storing charge for performing cardiac electrical stimulus, the method comprising: capturing a first predetermined number of selected cardiac events using the implanted electrodes; determining whether a threshold proportion of the first predetermined number of selected cardiac events are abnormal; determining treatment is indicated if the threshold proportion of the first predetermined number of selected cardiac events are abnormal for a second predetermined number of consecutive iterations, and, if treatment is indicated: initiating a charging operation for the energy storage system; and determining whether cardiac rhythm has returned to normal before stimulus is delivered and, if so, increasing the threshold proportion; wherein: the first predetermined number has an initial value of 24 and the threshold proportion has an initial value of 18/24, and the step of increasing the threshold proportion comprises increasing the first predetermined number to 27 and the threshold proportion to 21/27.