Cardiac event detection based on selective pacing for establishing a paced heart signal parameter baseline

An implantable device with ischemia detection and heart pacing capability, including:

• at least one electrode adapted for implantation in a body;
• circuitry coupled to the electrode to sense signals therefrom and to generate corresponding digital signals;
• pacemaker circuitry;
• a processor configured to:
• distinguish between at least two beat types, including ventricularly paced and supraventricular beats;
• collect the values of a heart signal parameter from the digital signals for ventricularly paced beats during a first time period;
• count the number of ventricularly paced beats during the first time period;
• if the number of ventricularly paced beats during the first time period is insufficient to establish a ventricularly paced baseline, direct the pacemaker circuitry to pace the heart for a second time period, the second time period being sufficiently long so that a ventricularly paced baseline can be established;
• derive a ventricularly paced baseline for the heart signal parameter, wherein the ventricularly paced baseline is indicative of a normal value of the heart signal parameter and wherein the ventricularly paced baseline is based at least in part on a plurality of values of the heart signal parameter collected during the second time period;
• measure the value of the heart signal parameter for ventricularly paced beats over a third time period;
• and
• identify ischemic beats by the application of ischemia detection criteria to the comparison of the values of the heart signal parameter for ventricularly paced beats over the third time period to the ventricularly paced baseline.