Detection of atrial tachycardia based on regularity of cardiac rhythm

A medical system comprising:

• a plurality of electrodes configured to sense cardiac activity of a patient;
• sensing circuitry configured to provide cardiac activity data based on the sensed cardiac activity, the cardiac activity data including at least one of electrogram (EGM) data or electrocardiogram (ECG) data;
• and
• processing circuitry configured to:
• determine an evidence level of an atrial tachycardia (AT) episode of the patient based on heart beat intervals in the cardiac activity data over a pre-determined time period;
• determine the evidence level indicates relatively regular heart beat intervals over the pre-determined time period in response to the evidence level corresponding to relatively regular heart beat intervals;
• determine the evidence level indicates relatively irregular heart beat intervals over the pre-determined time period in response to the evidence level corresponding to relatively irregular heart beat intervals;
• based on the determination that the evidence level indicates relatively regular heart beat intervals over the pre-determined time period:
• apply, to the cardiac activity data, a first set of AT detection criteria;
• and
• indicate a detection of the AT episode based on satisfaction of at least one of the first set of AT detection criteria;
• and
• based on the determination that the evidence level indicates relatively irregular heart beat intervals over the pre-determined time period:
• apply, to the cardiac activity data, a second set of AT detection criteria, the second set of AT detection criteria including at least one criterion different from the first set of AT detection criteria;
• and
• indicate a detection of the AT episode based on satisfaction of at least one of the second set of AT detection criteria;
• and
• communication circuitry configured to transmit data comprising an indication of the detection of the AT episode to a computing device, wherein the processing circuitry controls the communication circuitry to transmit the data.