Comparative Assessment of Cutoffs for the Cardio-Ankle Vascular Index and Brachial-Ankle Pulse Wave Velocity in a Nationwide Registry: A Cardiovascular Prognostic Coupling Study

Abstract

Pulse wave velocity (PWV) and cardio-ankle vascular index (CAVI) are measurements of arterial stiffness and are widely used as indices of arteriosclerosis. In Japan, brachial-ankle PWV (baPWV) is generally used to measure PWV, and while the reference value for this parameter is specified in Japanese guidelines for the noninvasive vascular function test, the CAVI reference value has not been standardized. We measured CAVI in 4,545 patients with at least one cardiovascular risk factor, and baPWV in 1,737 of these 4,545 patients on the same day as a part of an ongoing nationwide registry. The association between CAVI and baPWV was positive and significant ( r = 0.50, p < 0.001). The CAVI corresponding to baPWV 14 m/s derived from the regression line was 8.303 and the CAVI corresponding to baPWV 18 m/s was 9.059. The percentages of patients with low risk (CAVI < 8.303), medium risk (CAVI 8.303–9.058) and high risk (CAVI ≥9.059) were 35.0, 23.0, and 42.0% in 4,545 patients who underwent CAVI, respectively. The percentages of patients with baPWV < 14 m/s, baPWV 14–18 m/s and baPWV ≥18 m/s were 22.9, 47.3, and 29.8% in 1,737 patients who underwent both baPWV and CAVI, respectively. The average baPWV in low-risk patients (CAVI < 8.303, n = 642) was 14.97 ± 2.91 m/s, that in medium-risk patients (CAVI 8.303–9.058, n = 408) was 16.12 ± 2.80 m/s, and that in high-risk patients (CAVI ≥9.059, n = 687) was 18.40 ± 3.51 m/s. CAVI < 8.303 corresponded to a baPWV cutoff of 14 m/s, and CAVI ≥9.059 corresponded to a baPWV cutoff of 18 m/s. The results of this ongoing prospective study are expected to confirm the association between the CAVI reference value and cardiovascular events.