Letter by O'Rourke et al regarding article, "Arterial stiffness and cardiovascular events: the Framingham Heart Study".

Letter by O’Rourke et al Regarding Article, “Arterial Stiffness and Cardiovascular Events: The Framingham Heart Study” To the Editor: The article by Mitchell et al1 confirms the value of carotid-femoral pulse-wave velocity in predicting cardiovascular events in normal populations. This is embraced in the 2007 European Society of Hypertension/European Society of Cardiology guidelines in which pulse-wave velocity is seen as a measure of (aortic) target organ damage. The surprise is that the “comprehensive battery of measures of aortic stiffness and wave reflection” described in previous communications on this cohort were not mentioned and that only the simplest indexes of reflection—carotid augmentation index, brachial/ carotid amplification, and central pulse pressure—were reported and were not associated with cardiovascular events. Mitchell et al confidently dismiss the multiple studies that showed wave reflection to be important in predicting outcome and made no mention of the previous studies of vasculographs in the Framingham studies by Kannel et al2 that encouraged this view.3 There is good reason to question the techniques used by Mitchell et al to measure central from brachial waveforms. The method used to record the brachial pulse by applanation tonometry is suspect because the brachial artery wall cannot be applanated (flattened) against bone or ligaments as can the radial and carotid arteries and is sensed through the stiff bicipital aponeurosis. This is probably responsible for the insignificant (2 mm Hg) difference in pulse pressure between the brachial and carotid arteries4 and the very low value of amplification (1.06). In other studies,5 mean values of amplification were 1.34 in subjects of this age group, and values of aortic augmentation index were higher than the 15 13% reported here. The article by Mitchell et al helps to establish the value of pulse-wave velocity in epidemiological and clinical practice. Methodological issues of pulse waveform detection and calibration interfere with interpretation of wave reflection and pulse wave contour and need to be resolved. Disclosures Dr O’Rourke is a founding director of AtCor Medical Pty Ltd, a manufacturer of systems for analyzing the arterial pulse. The other authors report no conflicts.