Patent ID: 7616994

Claim:
A method comprising: detecting a ventricular tachycardia heart rhythm in a patient using an implantable medical device (IMD); providing anti-tachycardia pacing (ATP) therapy to the patient in response to the ventricular tachycardia heart rhythm; in response to the ATP therapy ending, determining an efficacy of the ATP therapy using the IMD by: waiting a first time duration after the ATP therapy ends during which time sensed ventricular depolarizations are ignored, wherein the first time duration exceeds first and second tachycardia detection threshold interval values; establishing a redetection time duration after the first time duration has elapsed; monitoring the ventricular depolarizations during the redetection duration, wherein the monitoring includes: measuring time intervals between the ventricular depolarizations; determining if a specified consecutive number of the intervals between the ventricular depolarizations are shorter than the first tachycardia detection threshold interval value, and, if so, then deeming that the ventricular tachycardia rhythm persists; and concurrently determining if, during the same redetection duration, a predetermined fraction of the consecutive intervals between the ventricular depolarizations are shorter than the second tachycardia detection threshold interval value that is different than the first threshold interval value, and, if so, then deeming that the ventricular tachycardia heart rhythm persists, wherein the fraction is less than 100%, otherwise, providing an indication of efficacy of the ATP therapy indicating whether the ventricular tachycardia rhythm is converted.