Preoperative brain magnetic resonance imaging and postoperative delirium after off-pump coronary artery bypass grafting: a prospective cohort study.

BACKGROUND

Delirium after cardiac surgery is a serious complication, increasing morbidity and mortality. Despite its high expectations, off-pump coronary artery bypass grafting (OPCAB) has largely failed to reduce the incidence of postoperative neurological complications. To further investigate the reasons for this failure, we used perioperative brain magnetic resonance imaging (MRI) to determine the relation between MRI findings and postoperative delirium.

METHODS

Altogether, 98 patients undergoing elective OPCAB were enrolled in this prospective observational study. Patients underwent brain MRI and magnetic resonance angiography (MRA) before and after surgery to identify cerebral infarction, white matter lesions, and intracranial artery stenosis. Postoperative delirium in the intensive care unit was measured using the delirium rating scale. The relation between postoperative delirium and MRI findings was examined using logistic regression.

RESULTS

Magnetic resonance imaging and MRA was completed in 88 (90%) of the patients. New ischemic lesions were present in seven (7.9%) patients. Delirium rating scale scores of 0, 1-7, and ≥ 8 were found in 25 (31%), 48 (60%), and seven (9%) patients, respectively. Multivariate logistic regression analysis revealed that new ischemic lesions (odds ratio [OR] 11.07, 95% confidence interval [CI]: 1.53 to 80.03; P = 0.017), carotid artery stenosis (OR 7.06, 95% CI: 1.59 to 31.13; P = 0.010), history of myocardial infarction (OR 3.78, 95% CI: 1.05 to 13.65; P = 0.043), and deep subcortical white matter hyperintensity (OR 3.04, 95% CI: 1.14 to 8.12; P = 0.027) were significantly associated with postoperative delirium.

CONCLUSIONS

Magnetic resonance imaging findings of new cerebral ischemic lesions, carotid stenosis, and deep subcortical white matter hyperintensity correlated significantly with postoperative delirium in patients who had undergone OPCAB surgery.