The Role of Preoperative Chronic Hypertension in Neurocognitive Decline after Cardiac Surgery: A Retrospective Cohort Study.

Abstract

Introduction: Patients frequently experience transient postoperative neurocognitive decline (NCD) after cardiac surgery with cardiopulmonary bypass. The goal of this study is to describe preoperative high blood pressure as a risk factor for NCD and use genomic expression to uncover its contribution to the pathophysiology of NCD.

Methods: This is a retrospective analysis of cohort study at a single academic center. Patients undergoing cardiac surgery with the use of cardiopulmonary bypass were administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) preoperatively, at postoperative day four, and four weeks postoperatively. Electronic medical records were reviewed for all recorded blood pressure from the year preceding surgery and intraoperative blood pressures. Blood samples were collected six hours preoperatively and six hours postoperatively to assess messenger ribonucleic acid expression.

Results: Eighty-seven patients completed postoperative day four testing, of whom thirty-seven experienced NCD (42.5%). Chronically elevated systolic blood pressure over the year preceding surgery was correlated with greater negative change in RBANS score at postoperative day four (P=0.03). Upon genomic analysis, macrophage markers were upregulated preoperatively, and anti-inflammatory and neuroprotective genes were downregulated postoperatively among patients who had a mean systolic blood pressure ≥ 130 mmHg.

Conclusion: Chronic exposure to elevated preoperative systolic blood pressure may increase the risk of NCD. The contributing role of preoperative hypertension in NCD may be partly explained by reduced attenuation of oxidative stress, increased inflammation, and reduced neuroprotection and heme metabolism postoperatively. This must be considered when assessing patient risks for cardiac surgery.