Neurocognitive deficit following aortic valve replacement with biological/mechanical prosthesis

The aim of this study was to objectively measure neurocognitive deficit following aortic valve replacement with a mechanical or biological prosthesis.

In this prospective, contemporary study we followed 82 consecutive patients undergoing isolated aortic valve replacement with either a mechanical (n=29, mean age=52+/-7 years) or a biological (n=53, mean age=68+/-10 years) valve prosthesis. Neurocognitive function was measured by means of objective P300 auditory evoked potentials (peak latencies, ms) and two standard psychometric tests (Trailmaking Test A, Mini Mental State Examination) before the operation, 7 days and 4 months after the operation, respectively.

Since P300 peak latencies increase with age, preoperative P300 measures are lower in patients receiving mechanical valves (360+/-35 ms, mean 52 years) as compared to patients receiving biological valves (381+/-34 ms, 68 years, P=0.0001). Seven days after surgery, P300 peak latencies were prolonged (-worsened) in both groups as compared to preoperative values (mechanical valves: 384+/-36 ms; P=0.0001 and biological valves: 409+/-39 ms; P=0.0001). Although on a different level (-age-related), this development was comparable within both groups (P=0.800). Four months after surgery, P300 peak latencies normalized in the mechanical valve group (372+/-27 ms, P=0.857 versus preoperative), while in contrast in the biological valve group they remained prolonged (417+/-37 ms, P=0.0001). We found no difference within patients receiving different types of biological or mechanical aortic valves.

Postoperative neurocognitive damage is not reversible in (-elderly) patients with biological aortic valve replacement, while in contrast postoperative neurocognitive damage is reversible in (-younger) patients with mechanical valve replacement. For this contrary development, age seems to be most important, whereas damage related to type of valve prosthesis may be overestimated.