High-Target Versus Low-Target Blood Pressure Management During Cardiopulmonary Bypass to Prevent Cerebral Injury in Cardiac Surgery Patients: A Randomized Controlled Trial.

Background: Cerebral injury is an important complication after cardiac surgery with the use of cardiopulmonary bypass. The rate of overt stroke after cardiac surgery is 1% to 2%, whereas silent strokes, detected by diffusion-weighted magnetic resonance imaging, are found in up to 50% of patients. It is unclear whether a higher versus a lower blood pressure during cardiopulmonary bypass reduces cerebral infarction in these patients.

Methods: In a patient- and assessor-blinded randomized trial, we allocated patients to a higher (70-80 mm Hg) or lower (40-50 mm Hg) target for mean arterial pressure by the titration of norepinephrine during cardiopulmonary bypass. Pump flow was fixed at 2.4 L·min·m. The primary outcome was the total volume of new ischemic cerebral lesions (summed in millimeters cubed), expressed as the difference between diffusion-weighted imaging conducted preoperatively and again postoperatively between days 3 and 6. Secondary outcomes included diffusion-weighted imaging-evaluated total number of new ischemic lesions.

Results: Among the 197 enrolled patients, mean (SD) age was 65.0 (10.7) years in the low-target group (n=99) and 69.4 (8.9) years in the high-target group (n=98). Procedural risk scores were comparable between groups. Overall, diffusion-weighted imaging revealed new cerebral lesions in 52.8% of patients in the low-target group versus 55.7% in the high-target group (=0.76). The primary outcome of volume of new cerebral lesions was comparable between groups, 25 mm (interquartile range, 0-118 mm; range, 0-25 261 mm) in the low-target group versus 29 mm (interquartile range, 0-143 mm; range, 0-22 116 mm) in the high-target group (median difference estimate, 0; 95% confidence interval, -25 to 0.028; =0.99), as was the secondary outcome of number of new lesions (1 [interquartile range, 0-2; range, 0-24] versus 1 [interquartile range, 0-2; range, 0-29] respectively; median difference estimate, 0; 95% confidence interval, 0-0; =0.71). No significant difference was observed in frequency of severe adverse events.

Conclusions: Among patients undergoing on-pump cardiac surgery, targeting a higher versus a lower mean arterial pressure during cardiopulmonary bypass did not seem to affect the volume or number of new cerebral infarcts.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02185885.