Techniques for delivering ESS to a heart of a patient are disclosed. An implantable medical device delivers ESS stimulation, and in some embodiments pacing stimulation, to a chamber of the heart via a first electrode set. The implantable medical device senses electrical activity within the chamber via a second set of electrodes. In some embodiments, the implantable medical device is able to apply a shorter blanking interval than is typical in the pacing art to a sense amplifier coupled to the second set of electrodes, allowing the implantable medical device to better detect arrhythmias and evoked responses. A variety of electrodes may be used in conjunction with the present invention; including without limitation, tip, ring, coil, can-based, endocardial, epicardial, pericardial, cardiac vein-based, subcutaneous, and/or surface electrodes.