Reproducibility of pulse wave velocity and augmentation index measured by pulse wave analysis

The aim of this study was to determine the reproducibility of pulse wave velocity (PWV) and augmentation index (AIx) measured using pulse wave analysis (PWA), prior to its use in large-scale clinical trials.

Arterial pressure waveforms were recorded and analysed using an established technique (Sphygmocor). Subjects with and without a range of recognized cardiovascular risk factors were studied to provide a wide range of values. Measurements were made after a brief introduction to the technique in a clinical setting. Two observers recorded aortic and brachial PWV in 24 subjects, each on two occasions, in a random order. In a separate study, two different observers used PWA to determine AIx in 33 subjects, each on two occasions, in a random order. Data were analysed using Bland-Altman plots and presented as mean +/- SD.

Brachial PWV was 8.65+/-1.58 m/s (range 6.16-10.95 m/s) and aortic PWV was 8.15+/-3.01 m/s (5.01-17.97 m/s). Within-observer variability was 0.14+/-0.82 m/s for brachial PWV and 0.07+/-1.17 m/s for aortic PWV. Corresponding between-observer values were -0.44+/-1.09 m/s and -0.30+/-1.25 m/s. AIx ranged from -15.0 to +45.0%, with a group mean of +19.6+/-12.0%. The within-observer difference was 0.49+/-5.37% and between-observer difference 0.23+/-3.80%.

PWA is a simple and reproducible technique with which to measure PWV and AIx. Reproducibility accords with that reported by other workers using different methodologies. PWA may, therefore, be suitable for large-scale population and intervention studies investigating the clinical relevance of vascular stiffness.