Implantable medical device configured to provide an intracardiac function

A leadless pacemaker device configured to provide for an intracardiac function, the implantable medical device comprising:

• a body formed by a housing of the leadless pacemaker device;
• a sensor arrangement arranged on the body and configured to receive a cardiac sense signal;
• and
• a processing circuitry operatively connected to the sensor arrangement, wherein the processing circuitry is configured to process the cardiac sense signal received using the sensor arrangement:
• to monitor the cardiac sense signal to detect whether a start criterion is fulfilled, wherein the start criterion is fulfilled if at least one signal sample (s(i−3) . . . s(i+3)) of the cardiac sense signal is smaller than a start threshold;
• and
• to start an atrial detection window for detecting, within the atrial detection window, a signal deflection of the cardiac sense signal indicative of an atrial event, based on whether said start criterion is fulfilled;
• wherein the processing circuitry is configured to detect the signal deflection in the cardiac sense signal indicative of an atrial event based on a comparison of the cardiac sense signal to a sense threshold in the atrial detection window,
• wherein the processing circuitry is configured to adjust a pacing function of the leadless pacemaker device based on the detected signal deflection.