Long-term neurocognitive function after mechanical aortic valve replacement

Background. Mechanical aortic valves are a possible source of microemboli potentially causing cerebral injury. Therefore, the long-term impact of mechanical aortic valve replacement on neurocognitive function is uncertain. Methods. In this prospective, contemporary study, we followed 32 consecutive patients (aged 51 +/- 8 years; range, 38 to 70; EuroSCORE [European System for Cardiac Operative Risk Evaluation] 4.4 +/- 1.7) undergoing isolated aortic valve replacement with a mechanical prosthesis. A cohort of age- and sex-matched patients (n = 28, aged 50 +/- 7 years) served as nonsurgical controls. After aortic valve replacement, neurocognitive function was serially reevaluated at 7-day (n = 32), 4-month (n = 31), and 3-year (n = 29) follow-up. Neurocognitive function was measured by means of P300 auditory evoked potentials. Results. Before the operation, P300 peak latencies were comparable between surgical patients (361 +/- 32 ms) and nonsurgical controls (365 33 ms, p = 0.783). In patients undergoing aortic valve replacement, P300 peak latencies were prolonged 7 days after surgery (380 +/- 32 ms) as compared with before the operation (361 32 ms, p < 0.0001) and as compared with nonsurgical controls (364 34 ms, P = 0.002). At 4-month (369 30 ms, P = 0.752) and 3-year (370 31 ms, p = 0.825) follow-up, P300 peak latencies normalized as compared with before operation and as compared with nonsurgical controls (4-month follow-up 363 31 ms, p = 0.832; 3-year follow-up 366 32 ms, P = 0.432). We found no difference in patients with different valve types. Conclusions. Despite previous assumptions based on the potential occurence of microemboli in patients with mechanical valves, mechanical aortic valve replacement has no adverse long-term impact on neurocognitive function. This finding is only valid for patients with a comparable age range undergoing isolated aortic valve replacement.