Postoperative Delirium and Cognitive Dysfunction after On- and Off-Pump CABG Surgery: A Prospective Trial in Aged Patients

Objectives: Postoperative delirium (POD) and cognitive dysfunction (POCD) are frequent after cardiac surgery in the aged, and impair postoperative recovery, cognitive prognosis and health care costs. This is a prospective explorative survey of predictive assessments, prevalence and clinical course of POD and POCD after on- versus off-pump coronary artery bypass grafting (CABG) in patients aged ≥70 years.

Methods: This is a subgroup analysis of a large prospective multicenter clinical trial. Inclusion criteria were age ≥70 years and elective CABG surgery without concomitant procedures. Twenty-nine off-pump and 29 on-pump CABG patients were enrolled in two university heart centers. All patients underwent clinical and neurocognitive assessments pre- and postoperatively.

Results: No differences were found between on- and off-pump groups with respect to baseline parameters. We found longer surgery-times in the on-pump group (200 vs. 243 min, p = 0.037) but no differences with respect to ICU and hospital stay. The prevalence of POD was 44.8% in the on-pump vs. 44.8% in the off-pump group (ns). In both groups, the median duration of the POD was 3 days and the maxima were 20 days. In the on- and off-pump groups, 24.1% and 13.8% of patients were rated pathological in the Interactive Confusion Assessment Method (ICAM) postoperatively (ns). In the Montreal Cognitive Assessment Test (MoCA), in both groups, patients differed by a median of 1 point pre- versus postoperatively (ns), two off-pump patients deteriorated distinctively by 4 MoCA-points. In the Trail Marking Test (TMT) on psychomotoric speed, we did not find significant differences pre- vs. postoperatively in both groups; however, in each group one individual strikingly deteriorated in the TMT performance, both had a POD. In the Counting Backward Test on attention, patients reached a median of 4 digits pre- and postoperatively in both groups (ns); however, preoperative impairment of attention (counting backwards £ 3 digits) predicted risk of POD.

Conclusion: Delirium is a relevant factor of morbidity in aged patients after CABG irrespective of the perfusion strategy. The percentage of patients rated deliriant by medical professionals was higher than in neurocognitive testing. The preoperative counting-backward-test probably allows a risk-assessment for delirium. Further research is mandatory with the aim to improve prediction, diagnosis, prevention and therapy of POD and POCD.

No conflict of interest has been declared by the author(s).