Is ambulatory arterial stiffness index a marker of large-artery stiffness? Evidence from intervention studies

The relationship between intraoperative surrogates of vascular stiffness, cerebral aneurysms, and surgical outcomes

OBJECTIVE

Increased arterial stiffness has been linked to aneurysm formation in the systemic and cerebral circulations, though the role played by arterial stiffness in the cerebral vasculature continues to be refined. This study assesses whether intraoperative surrogates of arterial stiffness differ between patients with cerebral aneurysms and controls, and the extend that these indices relate to outcomes following open surgical treatment.

METHODS

We evaluated patients in a prospectively maintained database who underwent cerebral aneurysm surgery, and compared them to controls without cerebral aneurysms. Arterial stiffness was estimated using the intraoperative ambulatory arterial stiffness index (AASI) and average pulse pressure (PP).

RESULTS

We analyzed 214 cerebral aneurysm patients and 234 controls. Patients in the aneurysm group were predominantly female and had a higher incidence of hypertension, diabetes mellitus, and vascular disease. They also demonstrate elevated AASI and average PP. When stratified by the occurrence of subarachnoid hemorrhage (SAH) or unfavorable neurological outcome, the AASI and average PP were not highly associated with the occurrence of SAH but were highly associated with unfavorable neurological outcomes. After multivariable analysis, both the AASI and average PP were no longer associated with unfavorable neurological outcomes, however elevated age, strongly linked with arterial stiffness, became a key predictive variable.

CONCLUSION

Readily obtained intraoperative surrogates of arterial stiffening demonstrates its presence in those with cerebral aneurysm disease and the extent that it does it may meaningfully direct their clinical course. However, multivariable analysis demonstrates limitations of using arterial stiffness measures to predict clinical outcomes.

The interactive effect of intra-beat and inter-beat blood pressure variability on neurodegeneration in older adults

Blood pressure variability (BPV) and arterial stiffness are age-related hemodynamic risk factors for neurodegenerative disease, but it remains unclear whether they exert independent or interactive effects on brain health. When combined with high inter-beat BPV, increased intra-beat BPV indicative of arterial stiffness could convey greater pressure wave fluctuations deeper into the cerebrovasculature, exacerbating neurodegeneration. This interactive effect was studied in older adults using multiple markers of neurodegeneration, including medial temporal lobe (MTL) volume, plasma neurofilament light (NfL) and glial fibrillary acidic protein (GFAP). Older adults (N=105) without major neurological or systemic disease were recruited and underwent brain MRI and continuous BP monitoring to quantify inter-beat BPV through systolic average real variability (ARV) and intra-beat variability through arterial stiffness index (ASI). Plasma NfL and GFAP were assessed. The interactive effect of ARV and ASI on MTL atrophy, plasma NfL, and GFAP was studied using hierarchical linear regression. Voxel-based morphometry (VBM) was used to confirm region-of-interest analysis findings. The interaction between higher ARV and higher ASI was significantly associated with left-sided MTL atrophy in both the region-of-interest and false discovery rate-corrected VBM analysis. The interactive effect was also significantly associated with increased plasma NfL, but not GFAP. The interaction between higher ARV and higher ASI is independently associated with increased neurodegenerative markers, including MTL atrophy and plasma NfL, in independently living older adults. Findings could suggest the increased risk for neurodegeneration associated with higher inter-beat BPV may be compounded by increased intra-beat variability due to arterial stiffness.

A cross-sectional study of the ambulatory central artery stiffness index in patients with hypertension

The present study aimed to investigate the characteristics of the ambulatory central artery stiffness index (AcASI) and its related factors. The association between AcASI and the left ventricular mass index (LVMI), and other factors related to atherosclerosis were explored.Patients with primary hypertension were enrolled into this study. Ambulatory central artery blood pressure (CABP) and ambulatory brachial artery blood pressure (BABP) were assessed using a Mobil-O-Graph NG hemomanometer, whereas AcASI and the ambulatory arterial stiffness index (AASI) were determined. LVMI was assessed by echocardiography.A total of 136 patients with primary hypertension were enrolled from May 2011 to January 2013 in Beijing Hospital. AcASI was significantly associated with AASI (r = 0.879, P < .001). AcASI was significantly lower than AASI (0.422 ± 0.302 vs 0.482 ± 0.270; P < .001). AcASI increased with age, ambulatory brachial mean blood pressure (MBP), and fasting glucose. AcASI was significantly associated with office pulse pressure (PP), ambulatory brachial PP, ambulatory central PP, and pulse wave velocity (PWV). AcASI, but not AASI, was significantly associated with LVMI. Receiver operator characteristic analysis indicated that AcASI and AASI could may be a predictor of left ventricular hypertrophy (LVH). Multiple regression analysis indicated that AcASI, chronic kidney disease, and hypertension course were associated with LVMI, but AASI was not.AcASI, which is obtained from ambulatory CABP monitoring, could be a new marker for the evaluation of atherosclerosis. AcASI may be stronger associated with LVH than AASI.