Background Aortic arterial stiffening is an independent predictor for future cardiovascular events. Calculation of Carotid-Femoral Pulse Wave Velocity (cfPWV) is currently the clinical gold standard for measuring arteriosclerosis, with cfPWV now recommended by the European Society of Cardiology for the guidance of initiating preventative treatments. Despite this, no consensus exists on how best to obtain the pathlength component of the calculation with large intercentre variation in how this is performed. The aim of the current study was to generate a calculation to produce a standardised pathlength that can be generated from easily obtainable clinical measures.

Methods 1183 participants free from cardiovascular disease (CVD) underwent whole body MRI as part of the TASCFORCE study. The distance between the carotid and femoral vessels was obtained by tracing the arterial centreline between the two. Backward linear regression was then used to generate a formula for calculating pathlengths based on easily obtainable clinical metrics. This calculation was then validated in an external cohort of 128 individuals with and without CVD who had also undergone MRI.

Results Various allometric and cardiovascular values were included in the analysis. Carotid-femoral pathlength could be calculated as follows:

Distance=100.36+(0.70×Age[years]) + (137.89×Height[m]) + (0.52×Weight[kg]) – (0.17×Pulse) + (46.16[female], 54.32[male]).

When compared with the actual measured distance in the original cohort this differed by −0.05 mm SD +28.5 mm, p=0.962 for difference. When this formula was then applied in the external validation cohort there was a small overestimation of the pathlength by 10.07±25 mm (p>0.001). This is comparable to clinically accepted techniques: measuring the direct distance from the carotid-femoral arteries and subtracting the measured to distance to the carotid-sternal notch, by tape measure or calliper on the body surface, results in mean overestimation of pathlength by −23.5±38 mm: a value greater than that of the generated formula technique.

Conclusion Using simple allometric measures, carotid-femoral pathlength can be calculated with good accuracy. This holds promise for improving interstudy and intercentre reproducibility, thus expanding the utility and applicability of PWV calculation in clinical practice. In future, the predictive ability of the formula can be tested in disease discrimination cohorts to further assess its clinical applicability