Increased augmentation index is paradoxically associated with lower in-hospital mortality in patients with acute ischemic stroke

Abstract

Objective: To evaluate the association between arterial stiffness and stroke severity and in-hospital outcome in patients admitted with acute ischemic stroke.

Methods: We prospectively studied 415 consecutive patients who were admitted with acute ischemic stroke (39.5% males, age 78.8 ± 6.6 years). On the third day of hospitalization, the following markers of arterial stiffness were recorded: central systolic blood pressure (cSBP), diastolic BP (cDBP), mean pressure (cMP), pulse pressure (cPP), augmentation index (AIx) and pulse wave velocity (PWV). The severity of stroke was assessed on admission with the National Institutes of Health Stroke Scale (NIHSS) score. The outcome was evaluated with rates of dependency at discharge (modified Rankin scale score between 2 and 5) and in-hospital mortality.

Results: None of the markers of arterial stiffness showed significant correlation with the NIHSS score on admission. However, there was a trend for an inverse correlation with AIx (r = -0.142, p = 0.064) and for a positive correlation with PWV (r = 0.235, p = 0.054). None of the markers of arterial stiffness differed between patients who were dependent at discharge and those who were independent. Patients who died during hospitalization had higher cDBP and cMP but lower cPP and AIx than patients who were discharged. In binary logistic regression analysis, independent predictors of in-hospital mortality were NIHSS score on admission (relative risk (RR) 1.16, 95% confidence interval (CI) 1.08-1.25, p < 0.001), presence of atrial fibrillation (RR 6.41, 95% CI 1.37-29.93, p = 0.018) and AIx (RR 0.94, 95% CI 0.89-0.99, p = 0.030).

Conclusions: Increased AIx appears to be associated with lower in-hospital mortality rates in elderly patients with acute ischemic stroke. Other markers of arterial stiffness do not appear to be associated with short-term outcome in this population.

Keywords: Arterial stiffness; Augmentation index; Central blood pressure; Pulse wave velocity; Stroke.