Abstract W P397: Severity of White Matter Hyperintensities Is Associated With Impaired Cerebral Autoregulation During Cardiac Surgery

Abstract

Introduction: Impaired autoregulation during cardiac surgery with cardiopulmonary bypass (CPB) is associated with perioperative mortality and morbidity. Identifying risk factors for impaired autoregulation during CPB surgery may facilitate risk stratification, and guide intra- and postoperative monitoring of high-risk patients. Hypothesis: We hypothesized that severity of white matter hyperintensities (WMHs) detected with MRI is associated with impaired cerebral autoregulation during CPB surgery. Methods: From a prospective cohort of 280 patients whom underwent cerebral autoregulation monitoring during CPB, 97 patients had research brain MRIs within 5-7 days of surgery. Intraoperative autoregulation monitoring was performed by generating a continuous moving Pearson’s correlation coefficient between mean arterial pressure (MAP) and cerebral blood flow velocity of the middle cerebral arteries measured with transcranial Doppler to generate the mean velocity index (Mx). Impaired autoregulation was defined as an Mx ≥ 0.4 at all MAPs. WMHs were assessed by blinded review of FLAIR images of all patients. WMHs were graded on a 0 to 9 scale. Logistic regression was used to explore associations between the degree of WMHs and impaired autoregulation as the primary outcome. Results: Twenty-two (22.7%) of 97 patients had impaired autoregulation. Age, sex, race, and other medical comorbidities did not significantly differ between patients with intact and impaired autoregulation. In univariate analysis, each 1-point increase in white matter (WM) score was associated with 1.64-fold increased odds (95% confidence interval [CI] 1.18-2.27, p=0.003) of impaired autoregulation. WM score remained an independent predictor of impaired autoregulation after adjusting for age, sex, race, hypertension, and prior stroke (OR 1.79, 95% CI 1.21-2.63, p=0.003). In adjusted models, severe white matter disease (WM score ≥3) was associated with nearly 5-times higher odds of impaired autoregulation compared to a WM score <3 (OR 4.75, 95% CI 1.58-14.27, p=0.005). Conclusions: WMHs are independently associated with impaired cerebral autoregulation during cardiac surgery and may increase the risk for perioperative morbidity and mortality.