THE INFLUENCE OF PREOPERATIVE COGNITIVE IMPAIRMENT ON THE CHANGES IN THE BRAIN'S ELECTRICAL ACTIVITY IN PATIENTS 1 YEAR AFTER CORONARY ARTERY BYPASS GRAFTING
Objective. To study the brain electrical activity changes at 1 year after coronary artery bypass grafting (CABG) in patients with and without preoperative cognitive impairment. Material and methods. Sixty-five patients (aged 45 to 69 years) after CABG were enrolled to the study. All the patients were divided into two groups before surgery: with mild cognitive impairment (MCI) ( n =27, Mini mental state examination (MMSE) scores 26.2±0.95) and without MCI ( n =38, MMSE scores 28.5±0.69). All patients underwent clinical and neuropsychological examination, as well as multichannel computer electroencephalography (EEG) 3-5 days before surgery and 1 year after CABG. Monopolar EEG recording in the range 0-50 Hz was performed from sixty-two sites according to the international 10-20 system. The EEGs recorded in the resting states with the eyes open and closed. Results. We revealed that the patients without preexisting cognitive impairment had better cognitive functions at 1 year after CABG as compared with preoperative data ( p =0.0007), whereas in the MCI group there was no improvement in cognitive status. MCI patients demonstrated diffuse theta-activity increase with eyes open state ( p <0.05), and an alpha activity increase in the left hemisphere with eyes closed in comparison with preoperative EEG values ( p =0.01). In addition, the patients with preexisting cognitive impairment had frontal alpha activity increase with eyes open at 1 year after CABG as compared with preoperative values ( p <0.05). Conclusions. It is suggested that the cortical dysfunction detected by computer EEG data at 1 year after CABG may be associated with worse postoperative recovery of cognitive functions in patients with preexisting cognitive impairment.