Cognitive deficit after aortic valve replacement

Background. Impairment of cognitive brain function after coronary artery bypass grafting (CABG) is well known. In contrast the potential neurocognitive damage related to aortic valve replacement (AVR) is uncertain. Methods. In this contemporary case-matched control study we followed 30 patients (mean age 70 years) receiving isolated AVR with a biological prosthesis. A cohort of sex-and age-matched patients (n = 30, mean age 70 years) receiving CABG with cardiopulmonary bypass served as controls. Cognitive brain function was measured by means of auditory evoked P300 potentials (peak latencies, ms) before the operation and 7 days and 4 months after the operation. Additionally, two standard psychometric tests (Mini-Mental State Examination and the Trailmaking Test A) were performed. Results. In preoperative measures there was no difference between patients undergoing AVR and patients undergoing CABG (AVR 378 37 ms, CABG 374 32 ms, P = 0.629). One week after surgery P300 peak latencies were prolonged (impaired) in both groups compared with preoperative values (AVR 405 43 ms, p = 0.001; CABG 398 +/- 44 ms, p = 0.004). At this point of follow-up there was no difference between the groups (p = 0.607). Finally, 4 months after surgery P300 auditory evoked potentials returned to normal in the CABG group (380 24 ms, p = 0.940) while in contrast in the valve group they continued to become prolonged (worsened) compared with preoperative values (410 47 ms, p = 0.005). At this time of follow-up P300 peak latencies were prolonged in AVR patients as compared with CABG patients (p = 0.032). The Trailmaking Test A and Mini-Mental State Examination failed to discriminate any difference. Conclusions. Four-month impairment of cognitive brain function is more pronounced in patients undergoing biological AVR as compared with age-matched control patients undergoing CABG. Further studies are needed to clarify the potential pathologic mechanisms causing an ongoing cognitive impairment in patients with biological aortic valve prostheses.