Neuropsychological Function After Coronary Artery Bypass Grafting

Sammanfattning: Despite considerable research efforts, the incidence and mechanisms of diffuse cognitive impairment after coronary artery bypass surgery are not fully understood. The aim of the dissertation was to describe cognitive changes after coronary artery bypass grafting (CABG) and the predictors and consequences thereof. Neuropsychological tests, interviews and questionnaires were used to assess objective and subjective cognitive function after coronary artery bypass surgery. Protein S100B was also evaluated as a possible biochemical marker for cognitive function, mortality, and emotional state. The results can be summed up in the following four points: 1. The choice of statistical definition and neuropsychological methods were significant predictors of the incidence of cognitive impairment after coronary artery bypass surgery. 2. There were no differences in subjective patient or spouse ratings of memory, concentration, emotional well-being, social functioning and general health 1-2 years after coronary artery bypass surgery and percutaneous transluminal coronary angioplasty. Only in memory function did patients and spouses report a postprocedural decline. 3. Elevated serum levels of protein S100B (>.3µg/L) 38-42 hours after cardiac surgery were an independent predictor of mortality 1-3 years after surgery. 4. After 3-6 years, patients with elevated S100B 38-42 hours after cardiac surgery had significantly higher state and trait anxiety compared with patients without elevated S100B levels. S100B was an independent predictor of state and trait anxiety. Patients with elevated S100B levels also rated their physical health as poorer. There were no differences in neuropsychological test performance, depression or blind interviewer ratings between the two groups. In conclusion, statistical and neuropsychological methods are decisive factors in defining the incidence of cognitive impairment after coronary artery bypass surgery. There were no differences in subjective measures of well-being in patients undergoing coronary artery bypass surgery compared with a comparable nonsurgical control group. Both groups reported a decrease in memory function; spouse and patient ratings were in agreement. Elevated S100B two days after surgery was a significant predictor of long-term mortality and anxiety, but not of neuropsychological function. The cause of the postoperative S100B elevation is largely unknown.