[Neuropsychological complications after coronary bypass grafting]

Coronary bypass grafting is more and more performed in elderly, atherosclerotic patients with increased risk of developing postoperative neuropsychological complications. In the present study, we investigated the relative importance of clinical, genetic or metabolic factors with possible impact on any of the primary endpoint encephalopathy, stroke and death after coronary bypass grafting.

98 prospective patients (mean age 67.9 years, 23 females, 75 males) underwent conventional elective bypass surgery. All had standardized cardiovascular risk factor assessment, prior stroke, EuroSCORE, a neuropsychologic battery and testing for Apolipoprotein E (APOE) Genotype and Homocysteine. Follow up was possible on 90 patients postoperatively and after 3, 6 and 12 months, monitoring cognitive decline, death or dependency and general health assessment.

Early mortality was 3.1 % (3 patients); 3 patients (3.0 %) developed postoperative ischemic stroke and 2 further strokes occurred within the next 3 months. Postoperative encephalopathy occurred in 14 patients (14.3 %). Homocysteine elevation or Apolipoprotein E 4 (APO E 4) did not correlate with immediate postoperative cognitive function. Patients with high EuroSCOREs had significantly lower postoperative Mini-Mental scores. Neither Homocysteine nor presence of an APO E 4 allele was associated with any postoperative endpoint at 3, 6 or 12 months after surgery. The EuroSCORE was modestly associated with postoperative encephalopathy (relative risk 1.3 - 1.5), but not with outcome after one year. Preoperative stroke was highly associated with postoperative ischemic stroke and cognitive decline on follow-up (relative risk 11), but not with postoperative encephalopathy.

Amongst clinical factors, the EuroSCORE may indicate moderate risk increase for acute postoperative encephalopathy. Most strokes occur early after surgery. Patients having suffered stroke prior to cardiac surgery may represent a high-risk group in the acute as well as chronic outcome after cardiac surgery.