Is arterial stiffness related to body height?

Letters to the Editor will be published, if suitable, as space permits. They should not exceed 1000 words (typed double-spaced) in length and may be subject to editing or abridgment. Experts 1 consider aortic pulse wave velocity (PWV) as the supreme index of arterial stiffness, mainly because it is an independent predictor of cardiovascular complications. 2 However , the noninvasive assessment of PWV is critically dependent on the measurement of the travel distance of the arterial pulse wave. 3 Variability between estimates of PWV largely depends on inconsistencies in the measured travel distance. 4 Travel distance is proportional to body height. 5 This explains the inverse association between PWV and body height. In a recent publication in Hypertension, Wang et al 6 recognized the problem and adjusted the hazard ratios expressing the risk of death related to a pulse wave reflection index for body height. The Colin VP-1000 (Omron Healthcare) is easy to operate and is used for risk stratification, in particular in Japan and China. 7 This device measures brachial-ankle PWV (baPWV) by means of an automated wave form analyzer. In 200 subjects (51.5% women; mean age: 51.3 years; age range: 20 to 80 years) recruited in the framework of the Flemish Study on Environment Genes and Health Outcomes, 8 we observed a strong inverse association between baPWV and body height (Table). However, the VP-1000 device computes baPWV automatically as (L1ϪL2)/T. 9 L1 is the distance from the heart to the ankle, L2 is the distance from the heart to the arm, and T is the time delay between the feet of the brachial and tibial arterial waveforms. The VP-1000 computes L1 and L2 from the height (H) of the subjects as L1ϭ0.2195ϫHϪ2.0734 and L2ϭ0.5643ϫHϪ18.381. 9 For this reason, we believe that the inverse association between baPWV and body height is spurious. Leading experts in the field recently proposed other formulas to extrapolate travel distance from height. 5 Another limitation of baPWV is that this index mixes the characteristics of the elastic aorta and subclavian arteries and the muscular brachial, femoral, and tibial arteries. In the same Flemish Study on Environment Genes and Health Outcomes participants, 8 we also measured aortic PWV from the length of the carotid-femoral segment and the transit time of the pulse wave. The carotid-femoral segment (cfD) was the distance between the suprasternal notch and the site of the femoral measurement (nfD) minus the distance …