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

## TL;DR

This study shows that high blood pressure before heart surgery increases the risk of brain function decline after surgery.

## Contribution

The study links preoperative hypertension to neurocognitive decline and identifies related gene expression changes.

## Key findings

- Chronic high systolic blood pressure before surgery correlates with greater neurocognitive decline at postoperative day four.
- Patients with high blood pressure showed upregulated macrophage markers and downregulated anti-inflammatory and neuroprotective genes.
- Preoperative hypertension may worsen postoperative outcomes through increased inflammation and reduced neuroprotection.

## Abstract

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.

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.

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.

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.