A medical device, comprising: an atrial pacing lead; a right ventricular lead; a left ventricular lead; and a microprocessor operably coupled with the atrial pacing lead, the right ventricular lead and the left ventricular lead and configured to sense cardiac signals, characterised in that the microprocessor is configured to provide pacing stimuli according to a minimal bi-ventricular pacing protocol in the absence of sensed atrioventricular decoupling and to provide pacing stimuli according to a conditional triple chamber pacing protocol if AV decoupling or a high burden circumstance is determined to be present; wherein the microprocessor is configured to (i) determine whether an AV interval burden associated with the sensed AV intervals is greater than a predetermined threshold, selected indicative of a percentage of i) time and/or ii) total cardiac cycles that the patient's atrio-ventricular interval exceeds a given value, wherein AV decoupling is determined to be present in response to the AV interval burden associated with the sensed AV intervals being greater than the predetermined threshold, (ii) and if AV decoupling is not determined to be present, to identify the presence of a predetermined high burden circumstance wherein the predetermined high burden circumstance is an indication of sleep, or an indication of exercise, or an indication of one or more of atrial pacing, increasing atrial pacing percentage, and upward change in programmed atrial pacing rate. an atrial pacing lead; a right ventricular lead; a left ventricular lead; and a microprocessor operably coupled with the atrial pacing lead, the right ventricular lead and the left ventricular lead and configured to sense cardiac signals, characterised in that the microprocessor is configured to provide pacing stimuli according to a minimal bi-ventricular pacing protocol in the absence of sensed atrioventricular decoupling and to provide pacing stimuli according to a conditional triple chamber pacing protocol if AV decoupling or a high burden circumstance is determined to be present; wherein the microprocessor is configured to (i) determine whether an AV interval burden associated with the sensed AV intervals is greater than a predetermined threshold, selected indicative of a percentage of i) time and/or ii) total cardiac cycles that the patient's atrio-ventricular interval exceeds a given value, wherein AV decoupling is determined to be present in response to the AV interval burden associated with the sensed AV intervals being greater than the predetermined threshold, (ii) and if AV decoupling is not determined to be present, to identify the presence of a predetermined high burden circumstance wherein the predetermined high burden circumstance is an indication of sleep, or an indication of exercise, or an indication of one or more of atrial pacing, increasing atrial pacing percentage, and upward change in programmed atrial pacing rate. (i) determine whether an AV interval burden associated with the sensed AV intervals is greater than a predetermined threshold, selected indicative of a percentage of i) time and/or ii) total cardiac cycles that the patient's atrio-ventricular interval exceeds a given value, wherein AV decoupling is determined to be present in response to the AV interval burden associated with the sensed AV intervals being greater than the predetermined threshold, (ii) and if AV decoupling is not determined to be present, to identify the presence of a predetermined high burden circumstance wherein the predetermined high burden circumstance is an indication of sleep, or an indication of exercise, or an indication of one or more of atrial pacing, increasing atrial pacing percentage, and upward change in programmed atrial pacing rate.