Pre-existing cognitive impairment as a factor influencing outcome after cardiac surgery

Conventional methodology to investigate cognitive impairment after coronary artery bypass graft (CABG) surgery leaves unclear the potential for pre-ex isting cognitive deficits to influence outcome. Individuals with pre-existi ng deficits may be more vulnerable to the effects of CABG, hence biasing th e results of a typical prospective trial if account is not taken of their s tate. The present study examined the effect of pre-existing cognitive impai rment upon cognitive outcome in 81 patients undergoing CABG. Patients perfo rmed the Stroop Neuropsychological Screening Test and other psychometric as sessments prior to and at 6 days and 6 months after CABG. Those with pre-ex isting cognitive deficits were significantly more likely to display impairm ent at 6-day and 6-month follow-ups than were those without pre-existing de ficits. Greater age and lower pre-morbid intelligence were also significant predictors of post-CABG deficit, confirming earlier findings. The results imply both that pre-existing cognitive impairments may render patients more vulnerable to post-operative deficits and that, in the absence of such pre existing impairments, CABG surgery does not inevitably lead to later defici ts. The study also replicated previous findings showing a similar influence of pre-existing depression upon emotional state after CABG. Overall, the r esults confirm the importance both of a patient's pre-existing cognitive an d emotional states, and the methodology to assess them, in influencing outc ome after cardiac surgery and the conclusions to be drawn as to the suppose d adverse effects of the procedure.