Patent ID: 8249702

Claim:
A method of cardiac signal analysis in an implantable cardiac stimulus device comprising electrodes configured for implantation in a patient, the method comprising: capturing a signal from the electrodes; detecting, using analysis of the captured signal, a series of detected events; and determining whether a malignant arrhythmia appears likely by: a) using an X/Y counter having an indication of likely malignant events (X) out of a set of detected events (Y); and b) comparing the X/Y counter to a predetermined counter ratio; and wherein the method also comprises the implantable device selecting the predetermined counter ratio using the following rules: c) if nonsustained high rate event conditions have not been previously detected, a first counter ratio is selected; and d) if nonsustained high-rate event conditions have been previously identified, a second counter ratio is selected, wherein the selection of the second counter ratio remains in place for use in identifying future malignant arrhythmias and avoiding unnecessary treatment of future nonsustained high rate event conditions.