OBJECTIVE: Arterial stiffness is a common change associated with aging and can be evaluated by measuring pulse wave velocity (PWV) between sites in the arterial tree, with the stiffer artery having the higher PWV. Arterial stiffness is associated with the risk of stroke in the general population and of fatal stroke in hypertensive patients. This study is to clarify whether PWV value predicts functional outcome of acute ischemic stroke. METHODS: One hundred patients were enrolled with a diagnosis of acute ischemic stroke and categorized into two groups: large-artery atherosclerosis (LAAS) or small vessel disease (SVD) subtype of Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification. Each group was divided into two sub-groups based on the functional outcome of acute ischemic stroke, indicated by modified Rankin Scale (mRS) at discharge. Poor functional outcome group was defined as a mRS > or = 3 at discharge. Student's t-test or Mann-Whitney U-test were used to compare maximal brachial-ankle PWV (baPWV) values. RESULTS: Twenty-four patients whose state was inadequate to assess baPWV or mRS were excluded. There were 38 patients with good functional outcome (mRS < 3) and 38 patients with poor functional outcome (mRS > or = 3). The baPWV values were significantly higher in patients with poor outcome (2,070.05 +/- 518.37 cm/s) compared with those with good outcome (1,838.63 +/- 436.65) (p = 0.039). In patients with SVD subtype, there was a significant difference of baPWV values between groups (2,163.18 +/- 412.71 vs. 1,789.80 +/- 421.91, p = 0.022), while there was no significant difference of baPWV among patients with LAAS subtype (2,071.76 +/- 618.42 vs. 1,878.00 +/- 365.35, p = 0.579). CONCLUSIONS: Arterial stiffness indicated by baPWV is associated with the functional outcome of acute ischemic stroke. This finding suggests that measurement of baPWV predicts functional outcome in patients with stroke especially those whose TOAST classification was confirmed as SVD subtype.