Serum S-100 protein release and neuropsychologic outcome during coronary revascularization on the beating heart: A prospective randomized study

Objectives: Our purpose was to establish whether coronary revascularization on the beating heart without cardiopulmonary bypass is less harmful to the brain than conventional surgery with cardiopulmonary bypass as indicated b y measures of cognitive function or by changes in serum concentrations of S -100 protein, a recognized biochemical marker of cerebral injury. Methods: We conducted a prospective randomized trial in which the assessors of the o utcome measures were blind to the treatment received. Sixty patients withou t known neurologic abnormality, undergoing coronary revascularization, were prospectively randomized to 1 of 2 groups: (1) cardiopulmonary bypass (32 degrees C-34 degrees C) and cardioplegic arrest ton pump) with intermittent antegrade warm blood cardioplegia or (2) surgery on the beating heart (off pump). Neuropsychologic performance was assessed before and 12 weeks after the operation. Serum S-100 protein concentration was measured at intervals up to 24 hours after the operation. Results: The groups had similar preope rative characteristics. There were no deaths or major neurologic complicati ons in either group, nor was there any difference between groups in the cho sen index of neurologic deterioration. Serum S-100 protein concentrations w ere higher in the on-pump group at 30 minutes, but any such difference betw een groups had disappeared 4 hours later. The extent of the changes in S-10 0 protein was unrelated to the index of neuropsychologic deterioration. Con clusions: The changes in S-100 protein concentration suggest that the brain and/or blood-brain barrier may be more adversely affected during coronary artery surgery with cardiopulmonary bypass than during surgery on the beati ng heart, but that this may not be reflected in detectable neuropsychologic deterioration at 12 weeks.