Techniques are provided for use by implantable medical devices for controlling
ventricular pacing. In one example, optimal atrio-ventricular and interventricular pacing
delay values are determined for pacing the heart of the patient based, in part, on a measured inter-atrial
conduction delay. Atrio-
ventricular conduction delays are then measured within the patient. The atrio-
ventricular pacing delays are compared with the measured atrio-
ventricular conduction delays. If the atrio-
ventricular pacing delays are less than the measured atrio-
ventricular conduction delays, biventricular pacing is delivered using the atrio-ventricular pacing
delay and the interventricular pacing
delay. However, if the atrio-ventricular pacing delays are not less than the corresponding atrio-ventricular conduction delays, as can occur if the inter-atrial
conduction delay is large, then alternative pacing regimes are selectively enabled, such as monoventricular pacing in the chamber having the longer
conduction delay value, biventricular pacing with negative
hysteresis, or biventricular pacing with pacing delays reduced using predetermined offset values.