Leadless cardiac pacemaker device configured to provide intra-cardiac pacing

A method for operating a leadless pacemaker device configured to provide for an intra-cardiac pacing, comprising:

• generating, using a processing circuitry, at least one ventricular pacing signals for stimulating ventricular activity,
• receiving, using a reception device, a sensing signal indicative of an atrial activity,
• detecting an atrial event (As) derived from said sensing signal, wherein the atrial event is a valid atrial sense event, where a series of atrial sense events lie within a range for a normal atrial rate, and/or when the atrial rate variability is within a certain range indicating a regular atrial rhythm,
• in case a valid atrial sense event is detected,
• determine a ventricular pacing event according to the atrial event based on a calculated atrial-ventricular (AV) delay,
• determine a calculated ventricular-atrial delay (VAcalc) indicative of a time delay at which an atrial event (As) is predicted to occur following a prior ventricular event (Vs),
• measure a true occurrence of a time delay (VAtrue) at which an atrial event (As) occurs following a prior ventricular event (Vs) and determine a correction value (CV) based on a timing relation between true occurrence of a time delay at which an atrial event (As) occurs following a prior ventricular event (Vs) (VAtrue) and the calculated ventricular-atrial delay (VAcalc),
• adjust said ventricular pacing timing based on the correction value (CV).