SUBCLINICAL CEREBRAL COMPLICATIONS AFTER CORONARY-ARTERY BYPASS-GRAFTING - PROSPECTIVE ANALYSIS WITH MAGNETIC-RESONANCE-IMAGING, QUANTITATIVE ELECTROENCEPHALOGRAPHY, AND NEUROPSYCHOLOGICAL ASSESSMENT

Objective: To analyze the frequency and severity of subclinical cerebr al complications associated with coronary artery bypass grafting (CABG ). Design: A prospective controlled study using preoperative and posto perative magnetic resonance imaging (MRI) of the brain, quantitative e lectroencephalography (QEEG), and detailed neuropsychological and neur ologic examinations as potentially sensitive indicators of subclinical cerebral injury associated with CABG. Setting: Multimodality evaluati on in a tertiary care unit (Kuopio University Hospital, Kuopio, Finlan d). Patients: Thirty-eight patients undergoing elective CABG and 20 co ntrol patients undergoing other major vascular surgery, mostly operati ons on the abdominal aorta. Main Outcome Measures: Coronary artery byp ass grafting-associated cerebral complications assessed preoperatively and postoperatively by brain MRI, QEEG, detailed neurologic examinati on, and a neuropsychological test battery that evaluates cognitive fun ctions in major areas known to be vulnerable to organic impairment (le arning and memory, attention, flexible mental processing, and psychomo tor speed). Results: There were no major neurologic complications. A m ild hemisyndrome developed in 1 patient who underwent CABG and in 1 co ntrol patient. Overall, there was no decline in mean cognitive perform ance 3 months after surgery. Electroencephalographic slowing of 0.5 Hz or more in at least 2 channels occurred in 11 patients who underwent CABG and in 1 control patient (P = .03). The postoperative brain MRI s can revealed new small ischemic lesions in 8 patients (21%) in the CAB G group but in none of the control group (P = .03). These new cerebral MRI lesions did not explain deterioration in neuropsychological test performance or the QEEG slowing. Conclusions: Coronary artery bypass g rafting causes more QEEG alterations and small ischemic cerebral lesio ns that are detectable by MRI than does other major vascular surgery. The effect is mainly subclinical, because no statistically significant deterioration in mean neuropsychological test performance was detecte d.