Heart sounds template comparison to identify true pacing mode

An apparatus comprising:

• an implantable therapy circuit configured to provide a bi-ventricular pacing pulse to a subject as part of cardiac pacing therapy, wherein the bi-ventricular pacing pulse includes providing an electrical stimulation pulse to a right ventricle and an electrical stimulation pulse to a left ventricle;
• a heart sound signal sensing circuit configured to produce a sensed heart sound signal that is representative of at least one heart sound associated with mechanical cardiac activity of a subject;
• a memory circuit configured to store one or more heart sound templates of cardiac capture;
• and
• a comparison circuit configured to:
• compare a segment of the sensed heart sound signal to the one or more heart sound templates of cardiac capture to identify ventricles in which cardiac capture was induced by the bi-ventricular pacing pulse;
• and
• generate an indication of the ventricles in which capture was induced according to the comparison and providing the indication to at least one of a user or process.