Higher blood pressure variability during hospitalisation is associated with lower cerebral white matter integrity in COVID-19 patients

Background: High blood pressure variability (BPV) is associated with cerebrovascular damage and dementia, but it is unknown whether short-term BPV during hospitalisation is also associated with cerebral white matter (WM) damage. We examined whether BPV, measured in-hospital using continuous monitoring, is associated with WM microstructural integrity in COVID-19 patients. Methods: We included hospitalised COVID-19 patients from the CORONavirus and Ischemic Stroke (CORONIS) study who underwent continuous vital signs monitoring using a wearable device during hospital admission and had an MRI shortly after discharge. Systolic BPV was calculated as Average Real Variability (ARV) and Coefficient of Variation (CV) with 1-, 5- and 20-minute intervals. We used diffusion tensor imaging to assess fractional anisotropy (FA) and peak width of skeletonised mean diffusivity (PSMD) as markers of WM integrity. Associations between BPV and WM integrity were examined with linear regression adjusted for age, mean systolic blood pressure (BP), number of BP measurements and type of respiratory support. Results: We included 47 COVID-19 patients (mean age: 59.6 years). BP was measured 6306 ± 4343 times per patient (median admission: 11 days (Interquartile Range [IQR] 7.5–15.0). Both higher ARV and CV were associated with lower WM microstructural integrity, reflected by lower FA (ARV: β = −0.40, p =.010; CV: β = −0.33, p = 0.026) and higher PSMD (CV: β = 0.28, p =.038) after adjustment for confounders. Correction for WM hyperintensities did not change these results. Conclusions: High BPV during hospitalisation is associated with lower WM integrity in COVID-19 patients, although causality needs to be demonstrated. Our findings need validation in hospitalised patients without COVID-19 to examine generalisability.