Definition of the Profile of Cognitive Deficit in Cardiac Surgery Patients Using the Optimal Clustering Method

An original clustering method based on discrete optimization of multidimensional objects according to many heterogeneous parameters: age, severity of carotid artery stenosis (CA), personal and cognitive characteristics was used to identify pre- and postoperative specificity of the profile of cognitive functions. The study involved 163 cardiac surgery patients. Determination of CA stenoses was carried out in the preoperative period using color duplex scanning and further classification of the lesion. Psychometric assessment of personal and situational anxiety, as well as psychomotor and executive functions, attention, short-term memory was performed 3–5 days before and 7–10 days after coronary artery bypass surgery (CABG). As a result of clustering arrays of 17 normalized indicators and subsequent analysis of three groups formed in this way, different dynamics of restoration of the profile of cognitive functions after coronary bypass surgery were discovered. One of the groups was designated as a group of cognitive reserves according to its best indicators of information selection and memory both in the preoperative and postoperative periods. Another selected group was characterized by a postoperative increase in the speed of information selection, but low memory scores. The third selected group demonstrated close relationships between indicators of attention, memory and the efficiency of a complex visual-motor reaction with age and the degree of stenosis of the CA, regardless of the pre- or postoperative testing period, which may indicate persistent disorganization of cognitive functions in such patients, requiring special attention when choosing neuro- and cardiac rehabilitation programs for them. The developed clustering method makes it possible to group patients according to a variety of heterogeneous parameters to identify the dynamics of their changes during the course of treatment.