In some examples, a leadless pacing device (LPD) is configured to switch from a sensing without pacing mode to ventricular pacing mode in response to determining that no intrinsic ventricular activity was detected within a ventricular event detection window for at least one cardiac cycle, which may be referred to as loss of conduction. The ventricular pacing mode may be selected based on whether atrial oversensing is detected in combination with the loss of conduction. In some examples, an atrio-ventricular synchronous pacing mode is selected in response to detecting loss of conduction and in response to determining that atrial oversensing is not detected. In addition, in some examples, an asynchronous ventricular pacing mode is selected in response to detecting both atrial oversensing and loss of conduction.
