ABSTRACT 51

CARDIOPULMONARY BYPASS AFFECTS COGNITIVE BRAIN DYSFUNCTION AFTER CORONARY ARTERY BYPASS GRAFTING

Juliane Kilo MD, Harald Baumer MD, Martin Czerny MD, Michael Gorlitzer MD, Daniel Zimpfer MS, Georg Grimm MD, Ludwig Kramer MD, Georg C. Funk MD, Christian Madl MD, Erst Wolner MD, Michael Grimm, MD

Background.  The causes of cognitive impairment after coronary artery bypass grafting (CABG) are still being discussed.

Methods and Results.  We prospectively followed 308 consecutive, unselected survivors of CABG at our institution.  In addition to determination of clinical parameters cognitive brain function was objectively measured by P300 auditory evoked potentials before CABG, at 17-day and at 4-month follow-up.  Standard psychometric tests (Trail Making Test A. Mini-Mental State Examination were also performed.

At 7-day follow-up cognitive P300 auditory evoke potentials were significantly impaired compared to preoperatively (peak latencies:  376 ± 40 ms vs. 366 ± 37 ms, p=.0001).  P300 measurements were almost normalized at 4 month follow-up (peak latencies: 369 ± 33 ms, p= n.s. vs. preoperatively).  Standard psychometric tests failed to detect this sub-clinical cognitive impairment.  Multiple regression analysis revealed that us e of cardiopulmonary bypass (CPB) was the only independent predictor of impaired cognitive brain function at 7 day (p<.0001) and 4 month follow-up (p=.0008).  The presence of diabetes mellitus (p=.0135) and concomitant repair of significant carotid artery stenosis (p=.0049) were predictive of late improvement of cognitive brain function at 4-month follow-up. 

Conclusions.  Objective cognitive P300 auditory evoked potential measurements demonstrate that the use of CPB is the only predictor of short – as well as long-term cognitive brain dysfunction after CABG.  Interestingly, the presence of diabetes mellitus and concomitant repair of significant carotid artery stenosis were predictive for long-term cognitive benefit.