Dual chamber pacemaker systems can lead to two forms of pacemaker-facilitated tachycardia—pacemaker-mediated tachycardia (PMT) and tracking of sinus or atrial tachycardia. Current pacemaker algorithms can not always differentiate between these two tachycardias. Various embodiments for differentiating these particular mechanisms of pacemaker-facilitated tachycardia, which is based on the specific termination response to PVARP extension are provided. The response to PVARP extension (V-A-A-V vs V-A-V) is a specific method for differentiation and can be used in conjunction with observations of atrial rate and electrogram morphology (or surface P wave morphology) for distinguishing between the two mechanisms of pacemaker-facilitated tachycardia.
