Method and system for determining a cardiac cycle pace time in accordance with metabolic demand in a leadless cardiac pacemaker system

A leadless cardiac pacemaker (LCP) configured to sense cardiac activity and to pace a patient's heart, the LCP disposable within a ventricle of the patient's heart, the LCP comprising:

• a housing;
• a first electrode secured relative to the housing;
• a second electrode secured relative to the housing, the second electrode spaced from the first electrode;
• a controller disposed within the housing and operably coupled to the first electrode and the second electrode such that the controller is capable of receiving an electrical cardiac signal from the patient's heart via the first electrode and the second electrode;
• a pressure sensor disposed relative to the housing and operably coupled to the controller, the controller configured to receive a pressure sensor signal from the pressure sensor, wherein the pressure sensor signal is responsive to an atrial contraction of the patient's heart;
• an accelerometer disposed relative to the housing and operably coupled to the controller, the controller configured to receive an accelerometer signal from the accelerometer, wherein the accelerometer signal is responsive to an atrial contraction of the patient's heart;
• the controller configured to determine a ventricle pace time for delivering a ventricle pacing pulse to the ventricle of the patient's heart, the controller determining the ventricle pace time based at least in part on an indication of an atrial contraction event of the patient's heart and an indication of a current posture of the patient, wherein the indication of an atrial contraction event is based primarily or exclusively on the received accelerometer signal if the indication of the posture of the patient is reclined, and is based primarily or exclusively on the received pressure signal if the indication of the posture of the patient is upright;
• and
• the controller is configured to generate and deliver a ventricle pacing pulse at the ventricle pace time.

A method of determining a ventricle pace time in a patient having a leadless cardiac pacemaker (LCP) implanted in their left ventricle, the LCP including a pressure sensor, the method comprising:

• determining or receiving an indication of metabolic demand;
• determining a ventricle pace time to achieve lower passive ventricular filling when the indication of metabolic demand exceeds a threshold;
• and
• determining the ventricle pace time to achieve higher passive ventricular filling when the indication of metabolic demand does not exceed the threshold.