Measurement of arterial stiffness in routine medical practice is important to assess the progression of arteriosclerosis. So far, many parameters have been proposed to quantitatively represent arterial stiffness. Among these, pulse wave velocity (PWV) has been most frequently applied to clinical medicine because those could be measured simply and non-invasively. PWV had established the usefulness of measuring arterial wall stiffness. However, PWV essentially depends on blood pressure at the time of measurement. Therefore, PWV is not appropriate as a parameter for the evaluation of arterial stiffness, particularly for the studies involving blood pressure changes.On the other hand, stiffness parameter β is an index reflecting arterial stiffness without the influence of blood pressure. Recently, this parameter has been applied to develop a new arterial stiffness index called cardio-ankle vascular index (CAVI). Therefore, CAVI does not depend on blood pressure changes during the measurements; CAVI could represent the stiffness of the arterial tree from the origin of the aorta to the ankle.Many clinical studies obtained from CAVI are being accumulated. CAVI showed high value in arteriosclerotic diseases, such as coronary artery diseases, cerebral infarction, and chronic kidney diseases, and also in majority of people with various coronary risk factors. The improvement of those risk factors decreased CAVI. Furthermore, the role of CAVI as a predictor of cardio-vascular events was reported recently.We review the clinical studies on CAVI and discuss the clinical usefulness of CAVI as a candidate surrogate end-point marker for cardiovascular disease.

We investigated whether cardio-ankle vascular index (CAVI), an arterial stiffness marker, independently predicts future cardiovascular events in subjects with metabolic disorders. 1562 outpatients underwent CAVI between April 2004 and March 2006 at Toho University, Sakura Medical Center in Chiba, Japan. Patients who already had cardiovascular events at baseline, patients with low ankle brachial index (＜0.9), and patients with atrial fibrillation were excluded. After exclusion, 1080 subjects with metabolic disorders including diabetes mellitus, hypertension and dyslipidemia were screened and followed prospectively. Eventually, 1003 subjects (92.9% of 1,080 subjects) followed until March 2012 (follow-up duration 6.7±1.6 years) were analyzed. During the observation period, 90 subjects had new-onset myocardial infarction or angina pectoris confirmed by angiography. All subjects were stratified into quartiles by baseline CAVI (Q1: CAVI ≤8.27, Q2: CAVI 8.28-9.19, Q3: CAVI 9.20-10.08, Q4: CAVI ≥10.09). Age, male ratio and future cardiovascular events increased as CAVI quartile became higher. In Cox proportional hazards regression analysis, the factors independently associated with higher risk of future cardiovascular events were every 1.0 increment of CAVI [hazard ratio (HR) 1.126, p= 0.039], male gender (HR 2.276, p=0.001), smoking (HR 1.846, p=0.007), diabetes mellitus (HR 1.702,p=0.020), and hypertension (HR 1.682, p=0.023). In individuals with metabolic disorders, CAVI was a predictor of future cardiovascular events, independent of traditional coronary risk factors. CAVI is a potentially valuable tool to identify persons likely to benefit from more intensive therapeutic approaches.

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Aim: Recently, a novel device for measuring the cardio-ankle vascular index (CAVI) as an arterial stiffness parameter has been developed. In this study, we evaluated the effect of angiotensin II receptor blocker (ARB) and calcium channel (Ca) blocker on CAVI in type 2 diabetic patients with hypertension. Methods: Seventy type 2 diabetes mellitus patients with hypertension were enrolled and randomly divided into two groups. One group was administered olmesartan medoxomil 10 mg/day for 12 months (ARB group), and the other group was administered amlodipine besilate 5 mg/day for 12 months (Ca blocker group). Results: In the ARB group, a significant decrease in CAVI was observed after 12 months; however, no significant change in CAVI was observed in the Ca blocker group although changes in blood pressure were almost the same. By simple regression analyses, CAVI changes correlated positively with 8-OHdG changes. Conclusions: Olmesartan, an ARB, improved arterial stiffness more than amlodipine, and this effect might be due to not only the blood pressure-lowering effect but also to reducing the potential of oxidative stress recognized in olmesartan.