Systems and methods for paired/coupled pacing

An implantable medical device that automatically controls an inter-pulse interval for delivering paired/coupled pacing pulses to a heart, said device comprising:

• a sensor configured to sense cardiac depolarizations;
• a pulse generator configured to deliver stimulation pulses to cardiac tissue;
• and
• a controller operatively coupled to the sensor and pulse generator and configured to:
• a) in the absence of a sensed intrinsic depolarization, cause the pulse generator to deliver a primary stimulus pulse to the heart, wherein the primary stimulus pulse amplitude is sufficient to capture cardiac tissue;
• b) cause the pulse generator to deliver a coupled/paired stimulus pulse to the heart at an inter-pulse interval, in connection with pulseless electrical activation (PEA), following one of i) detection of an intrinsic depolarization or ii) delivery of the primary stimulus pulse;
• c) sense for capture resulting from the coupled/paired stimulus pulse;
• d) in response to capture by a coupled/paired stimulus pulse, decrementing the inter-pulse interval by a first amount until there is no capture by a coupled/paired stimulus pulse, wherein the inter-pulse interval is set to prolong depolarization without inducing a separate contraction;
• and
• e) in response to no capture by a coupled/paired stimulus pulse, incrementing the inter-pulse interval by a second amount greater than the first amount, until capture by a coupled/paired stimulus pulse is detected.