Assigned the universe of knowledge Ω as composed by one target and two exogenous signals, the conditional joint transfer entropy (CJTE), assessing the amount of information jointly transferred from the two sources to the target that can be uniquely linked to one of the two sources, was found useful to study cardiovascular control. We propose the assessment of CJTE from systolic arterial pressure (SAP) and respiration (R) to heart period (HP) conditioned on R (CJTESAP, R→HPR) along the baroreflex, and from HP and R to SAP conditioned on R (CJTEHP, R→SAPR) along the feedforward mechanical pathway, in 134 patients undergoing coronary artery bypass graft surgery before (PRE) and after (POST) the induction of general anesthesia. In this group 38 patients developed atrial fibrillation (AF) after surgery, while the remaining individuals did not (noAF, n=96). Both CJTESAP, R→HPR and CJTEHP, R→SAPR distinguished AF from noAF individuals in the PRE condition, suggesting an impairment of HP-SAP closed-loop regulation in AF group and the possibility to identify subjects at higher risk to develop post-surgery AF.