Neurological complications after cardiac surgery: a retrospective case-control study of risk factors and outcome

Abstract

Background: To evaluate incidence, risk factors, and outcomes of postoperative neurological complications in patients undergoing cardiac surgery.

Methods: A total of 2121 patients underwent cardiac surgery between August, 2008 and December, 2013; 91/2121 (4.3%) underwent brain computed tomography (70/91, 77%) or magnetic resonance imaging (21/91, 23%) scan because of major stroke (37/2121, 1.7%) and a spectrum of transient neurological episodes as well as transient ischemic attacks and delirium /psychosis/seizures (54/2121, 2.5%). The mean age was 65.3 ± 12.1 years and 60 (65.9%) were male. Variables were compared among study- and matched-patients (n = 113) without neurological deficits.

Results: A total of 37/2121 (1.7%) patients had imaging evidence of stroke. Radiological examinations were done 5.72 ± 3.6 days after surgery. Patients with and without imaging evidence of stroke had longer intensive care unit length of stay (LOS) (13.8 ± 14.7 and 12.9 ± 15 days vs. 5.7 ± 12.1 days, respectively (p < 0.001) and hospital LOS (53 ± 72.8 and 35.5 ± 29.8 days vs. 18.4 ± 29.2 days, respectively (p < 0.001) than the control group. The hospital mortality of patients with and without imaging evidence of stroke was higher than the control group (7/37 patients [19%], and 12/54 patients [22%] vs. 4/115 patients [3%], respectively (p < 0.001). Multivariate analysis showed that bilateral internal carotid artery stenosis of any grade (p < .001), and re-do operations (p = .013) increased the risk of postoperative neurological complications.

Conclusions: Neurological complications after cardiac surgery increase hospitalization and mortality even in patients without radiologic evidence of stroke. Bilateral internal carotid artery stenosis of any grade, suggesting a diffuse patient propensity toward atherosclerosis, and re-do operations increase the risk of postoperative neurological complications.

Keywords: Atherosclerosis; CT-scan; Cardiac surgery; Carotid arteries; MRI; Neurocognitive deficits.

Fig. 1

a Axial DWI obtained in a 69-year-old man two days after cardiac surgery shows multiple small (arrow) and not small (*) ischemic strokes in both hemispheres. The patient had bilateral < 50% internal carotid artery (ICA) stenosis. Absence of significant ICA stenosis and bilateral distribution suggest an embolic origin of the strokes. b Axial DWI obtained in a 72 year-old woman two days after cardiac surgery shows a small hyperintense area (arrow) in the right posterior cerebral artery territory, consistent with small ischemic stroke. The patient had bilateral < 50% ICA stenosis. c Axial DWI obtained in a 69-year-old man three days after cardiac surgery shows a large, hyperintense area in the left middle cerebral artery territory, consistent with not small ischemic stroke. The patient had bilateral < 50% ICA stenosis

Fig. 2

Box-and-whisker plot of intensive care unit length of stay (LOS) (a, *p < .001 compared with control group, ^#p = .065 compared with neurological patients with imaging evidence of stroke) and hospital LOS (b, *p < .001 compared with control group. ^#p = .073 compared with neurological patients with imaging evidence of stroke). Horizontal line indicates median. Upper and lower margins of the box indicate 75th and 25th percentile of values, respectively. Whiskers indicate ranges

Fig. 3

Kaplan Meyer Curve for hospital mortality in control group and study group