NMDA receptor antibodies predict adverse neurological outcome after cardiac surgery in high-risk patients

The goal of this study was to compare the predictive ability of S100B, N-methyl-D-aspartate (NMDA) receptor antibodies (NR2Ab) and C-reactive protein (CRP) for neurological deficits after cardiac surgery with cardiopulmonary bypass (CPB).

We investigated 557 high-risk adult patients who underwent coronary artery or valve replacement surgery using CPB as a substudy of a prospective, blinded, multicenter clinical trial. Serum concentrations of S100B (n=513 patients), NR2Ab (n=398) and CRP (n=510) were measured preoperatively, 24 and 48 hours after CPB. Neurological adverse events were assessed at baseline and postoperative days 1 and 2; neurocognitive function (mini-mental status examination) was assessed at baseline and on postoperative days 1, 7 and 28.

Fifty-five (9.9%) patients had moderate or severe neurological adverse events (confusion/delirium, transient ischemic attack, or stroke) within 48 hours of CPB. Women had significantly more neurological complications than men (15.5% versus 7.8%; P=0.007). Ninety-six percent (24/25) of patients with NR2Ab concentrations > or =2.0 ng/mL preoperatively had neurological complications within 48 hours post-CPB, versus only 5.4% (20/373) of patients with NR2Ab concentrations <2.0 ng/mL, resulting in a 17.9-fold increase (95% CI, 11.6 to 27.6) in postoperative neurological complications for patients with high levels of NR2A antibodies. Preoperative serum S100B and CRP did not predict neurological complications from CPB. Decreased mini-mental status examination scores for orientation, attention and recall were associated with neurological adverse events early after CPB.

Preoperative serum concentrations of NR2Ab, but not S100B or CRP, are predictive of severe neurological adverse events after CPB. Patients with a positive NR2Ab test (> or =2.0 ng/mL) preoperatively were nearly 18 times more likely to experience a postoperative neurological event than patients with a negative test (<2.0 ng/mL).